Via the Mail and Guardian:

Obama rescues the Grand Canyon

Barack Obama took a big step towards preserving one of the world’s natural wonders on Monday, banning uranium mining on 400 000 hectares of land around the Grand Canyon.

The move, announced by the interior secretary, Ken Salazar, at a film screening in Washington DC, bans new mining claims around the canyon for the next 20 years. The area is rich in uranium deposits.

“A withdrawal is the right approach for this priceless American landscape,” Salazar said. “People from all over the country and around the world come to visit the Grand Canyon. Numerous American Indian tribes regard this magnificent icon as a sacred place and millions of people in the Colorado river basin depend on the river.”

Environmental groups said the move, which was opposed by the mining industry and some Republicans, would secure the American president’s environmental legacy.

The measure does not affect about 3 200 existing mining claims around the canyon, however. The administration said there would be continued development of 11 uranium mines.

Conservation groups said Obama had shown political courage in going ahead with the ban in the face of opposition. “Despite significant pressure, the president did not settle for a halfway measure,” said Jane Danowitz of the Pew Environment Group. In the final years of the George Bush presidency, when uranium prices were rising worldwide, mining companies filed thousands of claims in northern Arizona on lands near the Grand Canyon.

They also proposed reopening old mines adjacent to the canyon.

Salazar ordered a temporary halt to claims in 2009 after Obama came to office. Government officials proposed the 20-year ban in October last year, after an environmental review calling for the preservation of an “iconic landscape”.

The reality is that the Grand Canyon was never actually in any danger of being torn up for mining. That’s because the iconic expanse of canyon of eroded sandstone and river bed is located within the Grand Canyon National Park. It might depend a little on how you define the beginning and end of the canyon, but in general, the expansive “grand” part is all within the national park. Because it is within a national park, there can be no mining claims. The area is permanently and unquestionably protected and the only development and construction allowed is limited infrastructure for the park itself. (things like visitors centers, hiking trails and such.)

The park is enormous. It’s 1,902 sq mi or 4,927 sq km. It includes the canyon itself and much of the surrounding area. It was established as a National Monument in 1906 and has enjoyed the protection from commercial development of a US national park since 1919. There is absolutely no way that any part of that massive area will be mined for uranium or anything else.

The park is in Arizona, in a relatively sparsely inhabited region. Much of the area around the national park is federally administered land. As such, claims can be staked for mineral recovery. It’s not actually in the park and it’s certainly not in the canyon. It’s many miles away, but in the general region of the Grand Canyon. More than two thousand potential mining sites have been staked, many for uranium, as uranium can be found in the sandstone of the area. This is normal. Mining companies can, depending on the circumstances, claim or lease federal land for mineral recovery.

In 2009, it was proposed that a massive area that is only remotely close to the Grand Canyon be closed to mining. Now that decision has been extended, at least for the next twenty years. Vague environmental concerns are cited as the reason. There are already some long standing hard rock mines in the area, which apparently will still be allowed to operate.

I have to admit that I don’t actually have any expertise on this area or the eco-systems or whether it’s so unique or amazing as to make it worthy of complete protection from mining and development.   However, it should be made clear that regardless of the validity of this decision, this is not the Grand Canyon and the Grand Canyon was never in danger of being destroyed by mines.

Remote areas of Alaska are off the wider electrical grid and are far from natural gas pipelines or railways to deliver coal.   Heat may be provided, at least in part, by wood burning stoves that can use local fuel, although wood supplies may also be limited.   However, by far the most important source of energy is oil.   Diesel oil is the only way for these communities to generate electricity and provides most of the heat.   Petroleum also powers local transportation and powers the vital systems of the communities, either directly or by generating electricity.   Communications, drinking water wells, sanitary systems, heat and lighting all require energy provided by oil.

These communities use a lot of oil, and although they may have large storage tanks, the energy density of petroleum means that they can’t go very long without replenishment.   Getting the supplies to these communities is never a sure thing.   When it does arrive it’s expensive and it’s rapidly becoming more expensive as petroleum prices go up.  Due to both the costs of oil as a commodity and the difficulty in delivering it, the final cost can be upwards of ten US dollars a gallon when it is delivered.

Via NPR:

Ultra-Harsh Alaska Winter Prompts Fuel Shortages

ANCHORAGE, Alaska (AP) — Living in Alaska’s outer reaches is challenging enough, given the isolation and weather extremes, but at least three remote communities also have experienced weather-related late deliveries of fuel so crucial to their survival during an especially bitter winter.

The iced-in town of Nome and the northwest Inupiat Eskimo villages of Noatak and Kobuk faced fuel shortages that illustrate the vulnerability of relying solely on deliveries by sea or air, potentially subjecting communities to the mercy of the elements. The villages, which just received their fuel, are especially vulnerable, unable to afford more additional storage tanks for gasoline and heating oil, which can run as high as $10 a gallon.

Compounding a problem with no easy answers, temperatures dipping as low as minus 60 over the past few weeks means air deliveries are delayed at the same time people are consuming more fuel more quickly. Some people in both villages also use wood-burning stoves for supplemental heat, but diesel is the critical commodity.

“It’s been pretty tough,” Noatak resident Robbie Kirk said of life in the community of 500, which finally received a fuel delivery on Tuesday, three days after the village store ran out of heating oil. “We usually have a nice reserve of fuel. Now we’re just playing catch-up.”

Nome missed its pre-winter delivery of fuel by barge when a huge storm swept western Alaska. In a high-profile journey, a Coast Guard icebreaker is cutting path in thick sea ice for a Russian tanker delivering 1.3 million gallons of fuel to the community of 3,500.

Without a fuel delivery, Nome would likely run out of certain petroleum products before the end of winter and a barge delivery becomes possible in late spring.

Until recently, the situation was much more dire for the smaller communities of Noatak and Kobuk, located farther north above the Arctic Circle, where relentless extreme cold prevented fuel deliveries by plane until this week, residents say.

Before the new supply of fuel arrived in Noatak, the village store borrowed some heating oil from the village water and sewer plant, said store manager Connie Walton. But filling the store’s two 23,000-gallon tanks has diverted any potential crisis.

“We’re good for another month and a half,” Walton said.

Residents in Kobuk also were highly relieved by an air shipment of heating oil that arrived Wednesday in the village of 150 people about 175 miles to the east. It’s been too cold for people to use their snowmobiles much, so gasoline isn’t as much of a concern, said City Clerk Sophia Ward. Running low on the diesel used to warm homes was another matter.

“I’m glad that it came in today,” Ward said Wednesday. “It’ll keep our elders warm.”

In Noatak, residents once had fuel shipped by barge on the Noatak River, but that has long been impossible since the river shifted and became shallow there.

Two years ago, residents began tapping into another source of fuel, thanks to the Red Dog zinc mine 40 miles to the northeast. The mine in 2009 began a program to sell gasoline and diesel to Noatak and another close neighbor, the village of Kivalina. The fuel is sold at cost, said mine spokesman Wayne Hall.

“This is strictly for what we can do to help out our closest community members,” he said. “Energy and heating costs are one of the biggest costs to families in this region.”

The program lets individuals buy fuel on Saturdays every three weeks at a staging area about 23 miles from the village. This winter, they can buy gas in 55-gallon drums calculated at $4.89 a gallon. Villagers also bring their own drums to fill with diesel fuel at $4.35 a gallon.

The latest Red Dog fuel day for Noatak took place on the day the village store ran out of diesel. So villagers formed a convoy of about 30 snowmobiles and freight sleds, and headed out in weather marked by temperatures of 47 below and, for the first 10 miles, dense fog, said Kirk, who regularly takes advantage of the sales.

“It basically cuts my heating fuel in half,” he said. “It’s pretty critical for me.”

The state also helps lower the soaring cost of electricity in Alaska’s rural areas, spending almost $32 million in fiscal year 2011 through its Power Cost Equalization program, which subsidizes residential electric rates and the power bills of community buildings. Power in most villages is diesel-generated.

With so many scattered settlements of a few hundred or less, the logistics of keeping them all supplied is daunting. The very fact that oil would be brought in by air should drive home just how difficult and expensive an operation this is. Even when the system works and fuel and electricity are available, it’s always extremely expensive. The cost may be offset by subsidies, but that only shifts the burden to the government and tax payers. Ultimately, there’s no getting around the fact that getting hundreds of thousands of gallons of diesel to remote settlements is a costly undertaking.

There is, however, another option, which could provide these isolated communities with highly reliable and economical electricity and heat regardless of the weather they are experiencing. In recent years, a number of small modular nuclear reactor designs have been proposed. These are sometimes described as “nuclear batteries,” although the name is deceptive. They’re not batteries in the traditional sense, but rather are encapsulated fission reactors, designed to provide power for extended periods of time with minimal maintenance and upkeep. Refueling intervals may be years or decades. The idea that the reactor is a kind of “black box” that simply sits on site and provides energy.

While none of these reactors have been built, all are entirely possible with current technology. The biggest problem is not technical or safety issues but regulatory problems. In the US, all nuclear power reactors, regardless of size, face the same regulatory framework. A ten megawatt reactor must go through the same level of licensing, site studies and inspections as a 1700 megawatt reactor. It must carry the same level of insurance and have the same safety systems and evacuation plans. These regulatory requirements alone can cost hundreds of millions of dollars.

Some examples of small modular nuclear reactors:

• The Toshiba 4S – A small nuclear reactor capable of producing ten megawatts of electricity and also capable of being used for district heating.   The 4S is intended to be built underground a 30 meter deep shaft.   The reactor is sodium-cooled, although a version with lead coolant has also been considered.  It would provide maintenance-free energy for about thirty years, after which the core would be allowed to cool for a year and then be replaced.   A pilot plant has been proposed for construction in Galena, Alaska and has generally been well received by the local population.  With a population of only 612, the 4S would provide ample power to keep Gelena warm and electrified during the worst winters.   Construction remains delayed because of regulatory issues.   If the Gelena plant ever does get built, it is hoped it would provide a prototype for more reactors of this type in the near future.
• SSTAR – The SSTAR is a lead cooled nuclear reactor which would be constructed off site and delivered as a fully self-contained unit and used until in place until the end of the units lifespan, at which point it would be replaced.   It’s currently under development by the Lawrence Livermore National Laboratory.  Initial plans were to have a prototype operating by 2015, but there have been few recent updates on the progress of the program.  The SSTAR is expected to be capable of generating ten to one hundred megawatts of electricity, depending on the size of the unit.   The unit would have a thirty year lifespan.
• Hyperon Power Systems Reactor – Hyperon is a privately held company which has been working to develop and market a small, self-contained prefabricated nuclear power reactor for several years.  The initial proposal was to use a self-regulating uranium hydrate reactor.  Hyperon had claimed that this would be rapidly deployed as the technology had already been proven in numerous TRIGA reactors.  In 2009, the company announced that they were shelving the uranium hydrate design in favor of a lead-cooled fast reactor, citing difficulties in getting approval for the uranium hydrate reactor and delays in development.  However, the company has also indicated it may continue to move forward with the earlier reactor design as well.  The company indicated that it would begin shipments in 2013, but it’s not entirely clear whether this will actually happen.  The proposed reactors, if they are ever built, are expected to produce about 25 megawatts of electricity and have a lifespan of up to a few decades.
• Adams Atomic Engine – A design pioneered by our good friend and fellow nuclear energy supporter, Rod Adams.  The Adams Atomic Engine is a gas cooled pebble-bed reactor.  It would be created as a self-contained unit and available in a number of sizes and configurations, depending on the end use.   The Adams Engine would use nitrogen as the coolant and a closed-cycle gas turbine to generate mechanical power for electrical generation or marine propulsion.   A similar reactor, the ML-1, was designed and constructed by the US Army in 1963, but the design never made it past the prototype phase.  The Adams Engine would have a number of differences from the ML-1 thus avoiding most of the problems experienced by the ML-1 prototype.

There are only a few of the types of small, self-contained reactors intended for sights like the remote villages in Alaska.  There are others.  Many are liquid metal cooled and others are gas cooled and pebble bed type reactors.  a few small self-contained light water reactors exist too, such as the mPower reactor being developed by Babcock and Wilcox.   In general, the light water variety tend to be larger and, due to the lower burn up of light water reactors, they do not have as long a core lifespan and therefore do not allow for the reactor to be left in place for many years without refueling or maintenance.  

Molten salt reactors are also an excellent choice for small reactors with limited maintenance and extended refueling lifespans.   Because molten salt reactors can achieve very high burnup, they do not need frequent refueling and do not require large on sight spent fuel storage.   The passive safety of molten salt reactors is another important advantage as well as the fact that they can operate at very high temperatures, allowing for small modular gas turbine power conversion systems.   Flibe Energy is a venture aimed at marketing such reactors.

Assuming the regulatory hurdles could be cleared, these types of reactors offer vast benefits that could liberate areas of the world from reliance on expensive oil, transported long distances and requiring continuous resupply.

Some areas with constant energy supply issues that could benefit from a nuclear reactor (to name a few):

• Amundsen–Scott South Pole Station
• McMurdo Station (had one briefly)
• Scott Base
• Palmer Station
• Bellingshausen Station
• Thule Air Force Base
• Diego Garcia
• Guam
• Ascension Island
• Saint Helena
• Guantánamo Bay
• Kwajalein Atoll
• Wake Island
• Yellowknife
• Red Dog Mine
• Nome
• Prudhoe Bay
• Eareckson Air Station
• Numerous Islands in the Caribbean

But uh oh… it seems nuclear plant operators may have surfed the net

Via CNN:

NRC: Nuclear technicians surfed web on the job

Nine technicians responsible for monitoring operations at a Louisiana nuclear power plant spent on-duty time surfing the Internet — visiting websites that included news, sports, fishing and retirement information — jeopardizing the safety of the plant, federal regulators say.

The Nuclear Regulatory Commission disclosed the web-surfing activities Monday in a letter that proposes a $140,000 fine against the River Bend nuclear power station, 24 miles northwest of Baton Rouge.

No pornography sites were accessed, the Nuclear Regulatory Commission said. And importantly, the NRC said, the computer use did not present an avenue for hackers to gain access to reactor control systems, a modern-day fear at industrial plants.

But the NRC said the web-surfing control room operators were directly responsible for monitoring the reactor and other plant systems, and that their actions violated plant procedures requiring operators to remain attentive and focused on their work.

According to an NRC investigation, nine operators “deliberately violated” the safety procedures by surfing the web between January and April of 2010. Three of the nine did so with such frequency and duration that they are being issued “severity level three enforcement violations.” (Severity level one represents the greatest significant violation and severity level four is the lowest.) The remaining six operators will receive severity level four violations.

The operators were not named by the NRC.

An NRC spokesman said the proposed fine for web surfing is the only such action for web surfing in memory, and may be the only such action in the history of the agency.

In a notice to Entergy Operations Inc., operators of the River Bend Station, the NRC said that it appears that operators “remained attentive to reactor operations, indications, and alarms” while surfing the Internet.

“However, because most of the operators involved knew and understood” the prohibitions on Internet access, they exhibited “deliberate misconduct” and engaged in “hundreds of instances” of accessing the Internet from the “at-the-controls” area of the control room.

Score one for ridiculously reporting.

No, there was never a safety risk. While I don’t know exactly what the operators were assigned to do or how the systems operated here, all indications are that they were simply passing some time by surfing the net when they didn’t have any need to directly interact with the controls. Nuclear reactors certainly do not require continuous second by second human input nor do they need to have a reactor operator spending hours blankly staring at the dials that usually don’t change. Granted, all indicators are checked frequently, as they should be, but that was never interrupted.

It seems that in this case the operators were doing something many of us have: using company computers with internet access for personal surfing. Companies don’t like this, of course, because it tends to encourage employees to spend their time non-productively. If not for the internet, the operators might be more prone to doing something more useful for the company during the time they spend babysitting the control room. It’s like anything else, where the operator is primarily there for contingencies or if problems arise.

Still, this really just isn’t a news story. The workers never left their posts and they were ready to respond to any incident. That’s the important thing. I guess in the future they’ll have to go back to old fashioned paper crossword puzzles and magazines.

The solution to this problem has been the radioisotope thermal generator.   An RTG is a simple device, consisting of a strong particle-emitting isotope that produces heat and a thermoelectric generator which converts that heat into electricity.   The heat can also be used to keep vital components of the probe warm.  Unlike nuclear reactors, radioisotope thermal generators are extremely simple, have no minimum critical mass, produce little gamma and almost no neutron emissions, which could blind scientific instruments, and therefore require little or no shielding.  Modern RTG’s can provide hundreds of watts of reliable electrical power for years on end in a small, durable package.

The choice of isotope for space missions has always been, and continues to be plutonium-238. Plutonium-238 is a powerful alpha emitter which produces enormous amounts of heat energy.  Plutonium-238 produces only a small amount of low energy gamma emissions, making it easy to shield.  It’s easily prepared into ceramic oxide pellets that are chemically stable and have good thermal transfer.   With an 88 year half-life, plutonium-238 is short lived enough to be a good energy producer yet long lived enough to allow for missions of many decades.

All radioisotope thermal generators used for deep space missions have used plutonium-238.   RTG’s were also used to power the Apollo Lunar Surface Experiments Packages left by astronauts on the moon.    The RTG used for the Mars Science Laboratory provides 110 watts of electricity and uses about 4.5 kilograms of plutonium-238.  Larger RTG’s have been built for deep space probes, which provide up to 300 watts of power and use 7.8 kilograms of plutonium-238.  Some spacecraft have used multiple RTG’s, for example, Cassini was equipped with three RTG’s which provided a total of 900 watts of power to the spacecraft.

There are other isotopes that can also be used to provide power for RTG’s, but none are as desirable as Pu-238.   Strontium-90, a high energy beta emitter, which can be extracted from spent fuel, also produced significant amounts of heat, but would require substantially more shielding and produces less power per gram of material.  Isotopes of Curium have been studied as well, but also provide much less power and require greater shielding.  Americium-241 has also been considered, but at least four times as much material would be needed to produce the same amount of power, and greater shielding would also be required. Still, Am-241 is regarded as being the second most well suited fuel for RTG use.

Worldwide production of Am-241 is only a few kilograms per year, with US production capacity standing at only 500 to 750 milligrams annually.   Most of this material is already used to fill demand for smoke detectors and moisture gauges.  In order for the US to have a viable chance of using Am-241 as an RTG fuel, production would have to be ramped up significantly.

At one time, plutonium-238 was relatively cheap and easily available.  The United States had large stocks of the material and used it for numerous space missions.  Yet since the early 1990’s, that has not been the case.  Since then, only Russia has had the capacity to produce plutonium-238 and the price has skyrocketed.   US missions have been entirely dependent on plutonium-238 purchased from Russia at the cost of hundreds of millions of dollars.  Yet now even this limited supply is threatened, as Russia has begun to signal that it will no longer be able to provide the quantities of Pu-238 that the US (or potentially other nations) would require for continued space exploration.

Production of Plutonium-238:

The plutonium that can be extracted from light water spent fuel contains significant amounts of plutonium-238, but it’s combined with other isotopes of plutonium, making it unusable.  Separating out the plutonium-238 would require a complex plutonium enrichment system, which is far less practical than simply preparing the plutonium-238 on its own.

To produce plutonium-238, the first thing that is required is neptunium-237.  Neptunium-237 is produced as a byproduct of the reprocessing of spent fuel.   When a nucleus of uranium-235 absorbs a neutron, it will usually fission.  However, in a thermal spectrum reactor, some of the uranium-235 (about 18%) will absorb a neutron and not fission.  Instead, the uranium-235 becomes uranium-236.  Uranium-236 has a low neutron cross-section, so most of the uranium-236 generated in a reactor will just remain uranium-236, but a small amount of it does absorb a neutron and become uranium-237.  Uranium-237 has a very short half-life of only six days, decaying to neptunium-237.  Another source of neptunium-237 in spent fuel is the alpha decay or americium-241.

Spent fuel contains about .7 grams of np-237 for every one hundred kilograms of fuel.  That might not seem like much, but fuel reprocessing operations routinely go through hundreds of tons of fuel.   Because Np-237 is the only isotope of neptunium present in spent fuel in any significant quantity, it does not require any enrichment.  Instead, simply chemically separating the neptunium out yields nearly 100% neptunium-237.

After removing the neptunium-237, it is fabricated into targets which are irradiated with neutrons in a high flux reactor.   The targets are then removed and processed to separate out the plutonium-238 that is produced.  The plutonium-238 is then fabricated into RTG fuel tablets.

The end of US production:

The United States ended the practice of spent fuel reprocessing in 1977 when it was banned by the Carter Administration because of “proliferation concerns.”  Since then, the ban has been lifted, but as all reprocessing operations were shut down in the 1970’s and little support can be found for restarting the practice, the US still has no capacity to reprocess spent fuel.  After 1977, some material from plutonium production reactors continued, which yielded some neptunium-237, but that also ended in 1992, with the end of the cold war.

Today, the United States reprocesses no fuel at all and therefore cannot produce any neptunium-237.  There may still be some of the material remaining, though it’s doubtful that very much is left.   It should still be possible to obtain Np-237, purchasing it from countries with major spent fuel reprocessing programs, such as Russia, France or Japan.   However, this depends entirely on the willingness of such nations to provide it and may be expensive, since additional steps beyond normal reprocessing are required to produce the highly concentrated neptunium necessary for plutonium-238 production.

Getting enough Np-237, however, is not the biggest problem that the United States faces in producing Pu-238, however.   The US has a shortage of suitable reactors where the neptunium could be irradiated to produce the final plutonium-238 product.  Irradiating the targets requires a reactor with a very high neutron flux and the ability to receive materials for irradiation.  During the Cold War, the United States operated reactors at the Hanford and Savannah River sites primarily for the production of plutonium for nuclear weapons.  These same reactors could be used to irradiate materials for the production of medical and industrial isotopes along with materials like plutonium-238.  Therefore, up until the late 1980’s, the US had ample capacity for plutonium-238 production.   In the early 1990’s, the United States shut down all such reactors over “proliferation concerns.”   Russia, on the other hand, converted theirs to the full time production of peaceful isotopes, which is why they have been the world source for plutonium-238.

There are other reactors in the United States that could potentially produce plutonium-238, but not many of them.   The US has seen an unfortunate reduction in the number of research and irradiation reactors available.  Many, such as the Fast Flux Test Facility were shut down due to “proliferation concerns.”  Others like the High Flux Beam Reactor were closed after celebrities lobbied heavily against them.  Many simply were closed due to age and have not been replaced, given the lack of construction of new research reactors in the US in recent years.

There are only two reactors in operation that might be usable for producing plutonium-238.  One is the High Flux Isotope Reactor at the Oak Ridge National Laboratory.  However, the HFIR is already running at near full capacity for basic materials research and producing specialty isotopes.  It’s the only source of the vital isotope Cf-252 in the United States.  It also hosts a recently installed cold neutron source.   Because of this, the HFIR does not have enough available capacity to produce Pu-238.  That leaves one reactor: the Advanced Test Reactor.   The ATR is located at the Idaho National Laboratory.  It’s the only source in the US for production of cobalt-60, an isotope critical to medicine and industry.  It’s also one of only a few reactors that can be used to simulate extended fuel irradiation in a light water reactor, making it critical to fuel studies.  It’s not entirely clear to what extent producing Pu-238 at the Advanced Test Reactor might limit its capacity for other important functions.

The Advanced Test Reactor has been the focus of recent efforts to restart US Pu-238 production.   Several bills and proposals to begin production at the site have been floated, but funding has not been provided.  Most recently, a funding request for the relatively small amount of fifteen million dollars by the DOE was shot down by Congress.  No explanation was given, but it seems no US legislators are interested in restarting plutonoum-238 production, quite possibly because nobody’s spent any money lobbying for it and some have spent money lobbying against it.

Restarting production in the US may prove more difficult than simply finding a suitable reactor.   Producing the final Plutonium-238 tablets used for providing heat to RTG’s requires that the irradiated targets be dissolved, the plutionium-238 processed out and fabricated into the final RTG fuel.   The material is very hot, both in terms of radioactivity and literally.  Handling and processing it requires special facilities such as hot cells and plutonium chemical separation facilities.  The United States has limited capabilities in this area, with most of the facilities capable of fabricating special nuclear materials shut down over “proliferation concerns.”

That said, the US should have enough capacity for processing such materials to make at least a modest Pu-238 production program possible, if only funding is provided and the effort to do so is undertaken.   Ideally, enough would be made to allow for its use on spacecraft without extreme conservation measures taken, but that seems to be politically unlikely due to “proliferation concerns.”

In the end, we are left with a few options for the US space program, not all of them very appealing:

1. Restart domestic production of plutonium-238
2. Continue to rely on the limited Russian capacity to produce the material and hope they do not cut production or sales, as they seem to be indicating will happen.  Perhaps this could be avoided by paying an even more exorbitant amount to Russia for the material.  Continue with only limited deep space flights due to this limited source.
3. Hope that some other country steps up to the plate and starts making plutonium-238.  There’s a good chance that a country like China might start domestic production in the coming years, as they become more ambitious in their space program.  Whether they’ll share with the US is another issue.
4. Rely on another isotope that will result in less energy per kilogram, require greater shielding and therefore dramatically reduce spacecraft capabilities and increase launch expense.
5. Rely exclusively on solar power for space exploration.  Space exploration will therefore be limited to the inner solar system, out to about the orbit of mars and a little bit further, even out to Jupiter, although this will require very large solar arrays and will be restricted in capability due to very limited power capacities.   Beyond Jupiter, exploration by space probes will be impossible and will have to cease entirely.  And while exploration of the inner solar system will still be possible, landers that require significant amounts of continuous power will not be possible, thus making the Mars Science Laboratory the last of its kind.

Personally, I vote for choice 1.

They’re really great little items and the perfect gift for just about any occasion.   For one thing, they’re an interesting conversation piece and a very good example of a practical application of radioactivity.   They demonstrate that you can indeed keep something radioactive in our pocket and be quite safe and they’re very eye-catching.

They also have quite a bit of practical value.  Finding your keys in the dark is very easy with one of these key chains.  In fact, it’s so easy that if you happen to misplace your keys, the easiest way to find them is to turn off the lights.  When entering your home or starting your car in complete darkness, the glowing key chain provides just enough light to easily select the correct key and use it without fumbling.   If you happen to drop the keys on the dark floor of your car, you can find them very quickly and without effort.   You can even see the glow of the keys if they are under a seat or somehow otherwise obscured from direct view.  You can get different colors and use them to mark different key chains, making it very easy to grab the correct one, even in complete darkness.

I’ve had these key chains before (and broken a couple by mistake).  I can attest to just how useful they are.   There’s also no other way of getting this same value without using radioactive material.  An electrically illuminated key chain could not provide such continuous periods of glow without the batteries quickly running out.   Standard phosphorescent glowing items are limited to a few hours of illumination and must be exposed to light first in order to glow, making them useless for something like a key chain, which is often kept in one’s pocket.

There’s only one problem with these amazing little glowing key chains:  nobody in the US sells them, at least not directly.   Technically, these are not approved for sale or ownership in the United States, although I’ve never heard of anyone getting in trouble for owning one.  Many people do own them and talk about them openly online and elsewhere.  It might just be one of those things that hasn’t shown up on the radar of a bureaucrat who was asinine enough to bother to do something about it.

Still, there are stories about their thugs stopping sales of these key chains on sites like eBay.  It seems that these days most of those sold on eBay are coming from sellers who are not located within the United States.  Exactly how much trouble you could potentially get in for these remains unclear, but it appears to be a case of selective enforcement.  (So if you have one, don’t ever leave the federal government looking for an excuse to call you a terrorist.)

Yet while the government may tolerate people owning them, you can’t buy them from any major retailer.   They can be purchased on the “grey market,” imported in relatively small batches or sold over the internet.  They can be bought from foreign retailers, like those in the UK, who will generally ship to the US without problem.   The best place to buy them, however, tends to be eBay, where numerous sellers will sell to US customers.

That, however, was not good enough for me.  I know a great product when I see one and these things are inexpensive, extremely useful and very easy to sell.  I had bought one and people were constantly asking me about it and where to get one.   I wanted to sell these, and not just by keeping it on the down-low, selling them on auction websites or to friends.  I wanted to really sell them, importing them wholesale and selling them openly and in quantity.

I also didn’t want even the slight potential to have the NRC knocking at my door, which does occasionally happen when someone tries to sell them in the US.   One would think that the government has better things to do, but of course, they don’t.

I thought it would be easy to do.  After all, these things are very readily available in other countries, and by “other countries,” I don’t mean just Russia, Zimbabwe and Cuba.  They can be bought in the UK.  They are brought into the US all the time.  They’re also perfectly safe.   Of course, I assumed wrong, but this was a few years ago, long before I had gained a full understanding of the bureaucracy that is the NRC.

I e-mailed, called and faxed the NRC several times about this matter.  I cannot even begin to explain how difficult they were.   First, nobody at the agency seemed to understand what I wanted to do or what the devices were for.  They told me that if I wanted to start the process of getting a consumer product containing radioactive material approved, I could get some paperwork to start the ball rolling, but it would be several thousand dollars just to begin and would take more than a year.  I told them I believed the items qualified as being license-exempt, since other items of comparable function and contents, such as illuminated watches are.   They didn’t seem to understand what I was getting at.

After bouncing around many times between different individuals and sub-departments, before I eventually got the answer:  No, I could not import the key chains and no I could not sell them and nobody was really supposed to have them at all.   They never would tell me why the answer was no.  I was not told what exact regulation or requirement they violated.  They never would give me a straight answer about whether I could appeal that decision, who had made it or on what grounds and whether there was any way of having it reevaluated.  The best they could give me was that I could try the expensive process of getting a new product approved, but they also warned me that to do that I first had to have some prototypes of the product to have inspected and it would be illegal for me to have those prototypes unless I first got yet another license, permitting me to possess otherwise illegal amounts of tritium.

So the next place I went was the Health Physics Society.   They managed to put me in touch with some radiation safety experts who had worked with the NRC and knew the right people to ask.   After several false starts, they did manage to track down an NRC official who would go on record and explain the policy.   This is the e-mail I eventually got:

In response to your electronic mail dated October 23, 2007, concerning
keyrings containing tritium, the Nuclear Regulatory Commission (NRC) has
determined that a license is required to distribute products similar to
the Traser “glowring” key chains.  Although the devices are allowed in
the United Kingdom, they are not licensed here.  NRC regulations [10 CFR
30.19(c) and 10 CFR 32.22(b)] and policy (Federal Register Notice of
March 16, 1965, 30 FR 3462) do not allow licensing toys, novelties,
adornments or any consumer product containing radioactive material
considered a frivolous use of radioactive material and where the end use
of the product cannot be reasonably foreseen.   Other consumer products
that are not frivolous use, but contain self-luminous radioactive
material, must go through a two step safety review process consisting
of:  (1) an engineering evaluation and registration for the device as
well as (2) a licensing review of the program involved in possession and
distribution of radioactive material.

In order for NRC to be sure consumer products containing radioactive
material are safe for distribution to the general public the product
must be below a certain activity and/or found to incorporate engineering
features making release of the radioactive material unlikely.  In
addition environmental studies must show that during the products life
from manufacture to disposal, no adverse impact will be caused on the
environment or on those who may come in contact with the radioactive
material.  Traser Glowrings contain about 400 millicuries of tritium as
indicated by the UK manufacturer.  In comparison, a tritium wristwatch
typically contains 5 millicuries of tritium.  Tritium produces beta
radiation that cannot penetrate the skin, however, tritium can be
absorbed through the skin.  Tritium can also be an internal hazard
through inhalation and ingestion, as well as being absorbed through the
skin.

Again, Traser glowrings, and similar products, are not legal to own or
possess in the U. S. without a Federal and/or State license.

So that’s the big problem?   It’s an adornment or a novelty and therefore frivolous?

My Response:

• The fact that an item may be used as a novelty, adornment or toy does not mean it is “frivolous.”  The definition of “frivolous” is “irresponsible, lacking due consideration, without due consideration, improper.”  I think I can see what they’re getting at.  They want any item that is considered radioactive to have a legitimate use and consider entertainment or novelty to not be legitimate.  I have to disagree on that.   It’s fine to use something for such purposes if there’s negligible risk involved.
• The end use of the product can be reasonably forseen: people will put it on their key chain and use it to help locate their keys.
• At least part of the appeal of glowing key chains may indeed be their novelty and fashion aspect, but the same can be said of a tritium-containing wristwatch.   Watches are absolutely and undeniably fashion accessories, in addition to being functional timepieces.  In the cases of watches, the fact that they have a tritium-illuminated dial is often a selling point because of the fact that it’s fashionable in and of itself.   It’s not the only way to illuminate a watch dial.  It can be done with an electroluminescent face or with long lasting phosphorescent material.
• Radiolumonescent key chains are not only fashionable or novel, but also are practical.  They are at least as functional as radiolumonescent watches.  It makes it very easy to find misplaced keys simply by turning off the lights in a room.  The glow of the keychain is obvious in the dark even at a distance.   The glow can even be seen if the keys are partially obscured, such as being under a desk or bed.  The glow of the keychain also provides just enough light to aid a person handling the keys in the complete darkness, making it easier to select the right key for insertion into a lock or automobile ignition.
• While the amount of tritium in a key chain may be greater than that found in most watches, it is still trivial and is less than that found in numerous other commonly available items that can be purchased by the general public.  These include radiolumonescent compasses, small self-powered flashlight-style illuminators, self-illuminating map readers and other luminous items.   These devices are perfectly safe and do not pose any hazard to public health or the environment.  The amount of tritium present is far too low to pose a significant radiation hazard to anyone, even in the wost case scenario, where it might all be released in a confined area.
• Key chains of this style are already available in numerous countries around the world.  They have been sold for years without incident.   They are so common that it’s impossible to keep them out of the United States and there’s no legitimate reason to try anyway.  They’re safe and proven safe and their existence in no way enables terrorists, compromises public safety or constitutes a hazard.

I am willing to acknowledge that there may be legitimate reason for the NRC to require that the product undergo some kind of review, as they state, an engineering evaluation of the product.   Hopefully that would not include an environmental study, because that would be pretty ridiculous to do a study from scratch when there are already products of a similar nature being sold and which would release an equal amount of tritium upon disposal.  I’m not sure why they can’t just use a general purpose tritium device disposal study.  Although knowing the agency, it’s entirely plausible that they will require a completely new study. They could simply apply the same standard for release into the environment as any number of products with the same amount of tritium.  The danger presented is zero, at least if they are evaluated fairly and reasonably.

There are many exit  signs sold in the US which have much more tritium in them than one of these and the tritium is stored in tubes of almost exactly the same type.  Tritium-containing self-luminous exit signs may contain upwards of 40 curies of tritium, one hundred times the amount of tritium in one of these key chains.   It should be noted that these exit signs are subject to some special restrictions.  Those who purchase them are technically also purchasing an individual license for the sign, which requires that they do not tamper with the sign or open it and that they dispose of it properly, usually by returning it to the manufacturer.   Yet this certainly does not always happen.  Despite the requirement, thousands of tritium-containing exit signs of various ages (and therefore with various amounts of tritium present) end up in landfills and incinerators every year.  Despite this, the sky has not yet begun to fall.

I would be more than willing to consider undertaking the necessary engineering review, although I’m sure it would be long and expensive.   The products would almost certainly pass it.  They’re very straight forward and the manufacturer can provide any data necessary.  If an environmental study were also necessary, it still might be worth perusing.

The problem is that even if the manufacturer and distributors were willing to go through that process, the NRC has already decided the key chains are “frivolous” and therefore won’t even entertain the notion of approving them.   So it is simply impossible and they seem to not have the slightest willingness to revisit the decision.  DAMN!

Via HealthCanal:

New Take on Impacts of Low Dose Radiation
Berkeley Lab Researchers Find Evidence Suggesting Risk May Not Be Proportional to Dose at Low Dose Levels

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab), through a combination of time-lapse live imaging and mathematical modeling of a special line of human breast cells, have found evidence to suggest that for low dose levels of ionizing radiation, cancer risks may not be directly proportional to dose. This contradicts the standard model for predicting biological damage from ionizing radiation – the linear-no-threshold hypothesis or LNT – which holds that risk is directly proportional to dose at all levels of irradiation.

Imaging of a cell’s DNA damage response to radiation shows that 1.5 minutes after irradiation, the sizes and intensities of radiation induced foci (RIF) are small and weak, but 30 minutes later damage sites have clustered into larger and brighter RIF, probably reflecting DNA repair centers.

“Our data show that at lower doses of ionizing radiation, DNA repair mechanisms work much better than at higher doses,” says Mina Bissell, a world-renowned breast cancer researcher with Berkeley Lab’s Life Sciences Division. “This non-linear DNA damage response casts doubt on the general assumption that any amount of ionizing radiation is harmful and additive.”

Bissell was part of a study led by Sylvain Costes, a biophysicist also with Berkeley Lab’s Life Sciences Division, in which DNA damage response to low dose radiation was characterized simultaneously across both time and dose levels. This was done by measuring the number of RIF, for “radiation induced foci,” which are aggregations of proteins that repair double strand breaks, meaning the DNA double helix is completely severed.

Berkeley Lab biophysicist Sylvain Costes is generating 3D time lapse of DNA repair centers in human cells to understand better how cancer may arise from DNA damage. (Photo by Roy Kaltschmidt, Berkeley Lab)

“We hypothesize that contrary to what has long been thought, double strand breaks are not static entities but will rapidly cluster into preferred regions of the nucleus we call DNA repair centers as radiation exposure increases,” says Costes. “As a result of this clustering, a single RIF may reflect a center where multiple double strand breaks are rejoined. Such multiple repair activity increases the risks of broken DNA strands being incorrectly rejoined and that can lead to cancer.”

Costes and Bissell have published the results of their study in the Proceedings of the National Academy of Sciences in a paper titled “Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells.” Also co-authoring the paper were Teresa Neumaier, Joel Swenson, Christopher Pham, Aris Polyzos, Alvin Lo, PoAn Yang, Jane Dyball, Aroumougame Asaithamby, David Chen and Stefan Thalhammer.

The authors believe their study to be the first to report the clustering of DNA double strand breaks and the formation of DNA repair centers in human cells. The movement of the double strand breaks across relatively large distances of up to two microns led to more intensely active but fewer RIF. For example, 15 RIF per gray (Gy) were observed after exposure to two Gy of radiation, compared to approximately 64 RIF/Gy after exposure to 0.1Gy. One Gy equals one joule of ionizing radiation energy absorbed per kilogram of human tissue. A typical mammogram exposes a patient to about 0.01Gy.

Corresponding author Costes says the DNA repair centers may be a logical product of evolution.

“Humans evolved in an environment with very low levels of ionizing radiation, which makes it unlikely that a cell would suffer more than one double strand break at any given time,” he says. “A DNA repair center would seem to be an optimal way to deal with such sparse damage. It is like taking a broken car to a garage where all the equipment for repairs is available rather than to a random location with limited resources.”

However, when cells are exposed to ionizing radiation doses large enough to cause multiple double strand breaks at once, DNA repair centers become overwhelmed and the number of incorrect rejoinings of double strand breaks increases.

“It is the same as when dozens of broken cars are brought to the same garage at once, the quality of repair is likely to suffer,” Costes says.

You can read the rest of the article here. The level of the data available is new, but the conclusion is not. The available data that has been collected for decades on both a microscopic and macroscopic level clearly shows that radiation dose does not produce a linear level of dna damage until it reaches a relatively high exposure level.

Unfortunately, this has never seemed to unseat the suborn linear non-threshold model, which continues to be the standard for most radiation exposure policy. I also doubt that this new data will do much to change that, although when studies like this do come out, it is certainly worthwhile to try to raise as much publicity as possible for it.

From the standpoint of nuclear energy policy, this data almost seems moot. The actual radiation level that the public is exposed to from nuclear energy is so tiny that even if LNT is used as the standard for exposure limits, one comes to the inevitable conclusion that it is more important to tear down all the granite buildings than to stop using nuclear energy. Therefore, no scientific data is ever likely to unseat the radiation argument against nuclear energy, because it was never based on science to begin with.

Fission was recognized as a potential energy source after the possibility of a fission chain reaction was realized.  A chain reaction occurs when neutrons produced by nuclear fission strike other fissile nuclei, releasing more energy in a self-sustaining reaction.   In 1942, an experiment at the University of Chicago proved that nuclear fission could indeed produce such a chain reaction.   The first artificial fission reactor was created by piling large amounts of uranium together with ultra-pure graphite blocks.  The graphite slowed neutrons, making them easier to absorb by the uranium nuclei, resulting in the fission chain reaction.  In 1945, the first artificial fission chain reaction to occur without the aid of a moderator when the first nuclear weapon detonated in the Trinity test.  The Trinity device used plutonium as the fissile material, an element produced in nuclear reactors at the Hanford site.   Plutonium is too short-lived to be found in large quantities in nature.  Another bomb, fueled by uranium was the result of years of painstaking isotope separation, which increased the amount of fissile uranium-235 available to far beyond what is found in natural uranium samples.

For many years, it was believed that such fission reactions were always limited to these artificial circumstances.   Nuclear fission, it was thought, was the result of painstaking efforts by mankind to gather up the necessary materials, enrich beyond their natural concentrations and either bring them together rapidly in large quantities or place them in the special conditions inside a reactor, where neutron moderators make it possible to sustain nuclear fission.

In 1940, Russian scientists observed the phenomena of spontaneous fission, where heavy elements like uranium split on their own without the need for a neutron to cause the event.  It was also known that uranium atoms could split as the result of a neutron generated by cosmic rays.   However, such events are uncommon and produce little energy.   They are distinct from the chain reactions that had only been observed in human-created nuclear reactors.

All this changed in 1972, when an unusual discrepancy in the concentration of uranium-235 from a mine in Gabon Africa was detected.  Chemical analysis of a unique uranium deposit  indicated that the formation had sustained a fission chain reaction at one time.   The possibility of a natural nuclear reactor of this type had been suggested as early as 1956, but the Gabon discovery was the first time that such an event was confirmed to have happened.  Further investigation of the site identified at least sixteen regions of the deposit where the concentration of uranium and lighter elements clearly indicated that significant amounts of nuclear fission had occurred.

The reactor at Gabon operated about 1.7 billion years ago, producing chain reactions for at least hundreds of thousands of years.   It was remarkably similar to modern, artificial nuclear reactors.   Fission occurred when water seeped into cracks and pores in the deposits of extremely high grade uranium ore.   The water acted as a moderator, causing the chain reaction.   In modern times, water can only be used as a moderator in reactors where the uranium has been slightly enriched to contain more uranium-235 than found in nature, but because uranium-235 has a half-life of about seven hundred million years, there was a great deal more when the Gabon reactor was critical.

Exactly how long the Gabon reactor was critical or how much energy was released is not known.   Scientists have estimated that it probably generated about 100 kW of power and likely operated intermittently due to the buildup of neutron poisons and variations in the water levels in the rock.   It also generated some amount of plutonium-239 and other heavy isotopes, which would have added to the available fissile fuel.

There has been some debate about just how common reactors like that found in Gabon may have been.   While the Gabon deposit is the only one that is known to have sustained nuclear fission, that certainly does not mean it was the only one.  In fact, there were almost certainly others, possibly many others.  The geological record is incomplete for the period of time that the Gabon reactor was critical.  The vast majority of geological formations from over a billion years ago have long been obliterated by erosion, subduction, volcanic activity and other forces that continuously shape the earth’s crust.    Even if these reactors were once common on earth, we would not expect to find the evidence and the fact that at least one still exists intact at all may be sheer luck.

What is known is that deposits of uranium in concentrations high enough to potentially sustain such reactions are fairly common, even today, and while they don’t have the necessary isotopic concentrations to produce a fission chain reaction, they would have in earth’s early history.   The further back one goes, the higher the concentration of uranium-235 would be and thus the more easily a fission reactor could have come together.  Debate continues about the time scale when such reactors could have functioned, with some arguing that such naturally occurring uranium concentrations would require high levels of oxygen in order for the necessary geochemical processes to occur.

Yet the lack of a complete geological record ultimately makes it impossible to know for certain.   Reactors may have been very commonplace billions of years ago and they may have existed for some time after the period the Gabon reactor was dated to.   It’s remotely possible that a combination of plutonium produced within such reactors and the presence of better moderating materials, such as naturally-occurring beryllium allowed these formations to produce fission chain reactions even more recently than would have been possible with the Gabon reactor.

All that can be said is that there was a period of time in Earth’s distant history when natural nuclear reactors were possible and existed and they may very well have been fairly commonplace.   This itself is a huge revelation.

A reactor at the center of the earth?

Upon learning of the natural reactor discovered at Gabon, nuclear chemist J. Marvin Herndon hypothesized that nuclear fission might actually be far more central to the formation and conditions of earth than had been previously though.   Herndon suggested that if sufficient uranium existed in the core of the earth, it could result in a massive fast fission reactor, which would be capable of producing enough fuel through breeding to sustain fission for billions of years.

Herndon’s assertions have not generally been accepted by the mainstream geological community.   Direct evidence of such a reactor is relatively limited, although the levels of helium isotopes measured in volcanic samples have been intriguingly close to those that the hypothesis predicts. None the less, if true, the georeactor hypothesis would be an elegant explanation for a number of observed phenomena.   It would explain the source of apparently excessive heat in the earth’s core and mantel, which has traditionally been attributed exclusively to nuclear decay.   It also could explain the mysterious phenomena of magnetic pole reversal, which could have been caused by periods when the reactor stopped due to the buildup of neutron poisons, only to start again once they had decayed away.

There is, however, some other data which appears to dispute the possibility of a reactor at earth’s core.  It such a reactor did exist, the bulk of the earth would prevent gamma rays or neutrons from being detectable, but it should still be possible for neutrino detectors to measure the characteristic neutrinos generated from fission reactions in earth’s core.   The data from such detectors does not support the hypothesis that a nuclear fission reactor provides a significant proportion of the heat in the core and mantle of the earth.   Such a reactor could still exist, but it would have to be less than about three terawatts or a greater number of neutrinos should have been detected coming from the earth’s core.  In that case, the reactor would only account for a small portion of the 40 terawatts of observed geothermal activity.

While the neutrino data may seem to indicate that a large nuclear reactor is not currently operating within the earth, it does not rule out the possibility that such a reactor has operated intermittently and that it is currently either not producing a fission chain reaction or is only producing a small one.   Even if that is the case, the residual heat of such a reactor would be very significant.   It is also possible that a redactor existed at one time, perhaps billions of years ago, but has not produced a chain reaction since.   If this is the case, the implications are still enormous for the formation of the earth and the heat and magnetic fields observed to this day.

Implications for earth and beyond:

We really do not know if there is indeed a georeactor or if there ever was.  While the hypothesis is controversial, it cannot be completely discounted and must be considered a possible factor in the structure and formation of the earth.  The implications are quite profound and could rewrite our most basic presumptions of the planets history and formation.

What we can say for sure is that nuclear fission reactors did exist on earth, at least in the crust.  The influence of such reactors must now be considered as an influence on everything from the mineralogy of the earth’s crust to the formation of early life.   The amount of uranium and its daughter products observed in the modern earth may be less than what once existed due to much of the element fissioning away.   Some of the lighter elements that are abundant in the crust may be the byproducts of this fission.  The heat generated by these reactors could have played a major role in shaping the early geology of earth.  It may have even influenced life, possibly heating bodies of water or producing hot springs, where heat-dependent microbes flourished.   It’s even possible that the ionizing radiation generated by the reactors was a factor in the early formation and evolution of organisms.

But even if fission chain reactions did not play a major role in the history of earth, it does not diminish the potential importance on a cosmic scale.   If fission occurred naturally on earth, then we can be certain that occurred naturally elsewhere and continues to occur naturally elsewhere in the universe.   Similar reactors could have existed on other terrestrial planets in our solar system or may have contributed significant amounts of energy to the primordial planets as they formed around the sun.   It has been suggested that fission reactions could also account for the energy observed from the gas giant planets of the solar system.

With more than a billion billion stars in this galaxy alone, there are certainly other places where fission occurs and where it could easily play an important role in how planets form or how life might develop.  As a source of energy, fission could potentially provide the heat necessary for life to exist on planets or planetoids too far from stars to otherwise support life.   It could even mean that otherwise frozen bodies in interstellar space could harbor life.   This alone could vastly change our current ideas of where life might exist beyond earth.

The suggestion that fission could also play a role in the ignition of stars is yet another intriguing, if unorthodox hypothesis that needs to be at least considered.

Whatever role fission plays in the energy balance of the earth and the universe, we now know that it does play some role.  It happens.   It’s a fundamental reaction and a source of energy in nature.  It must be considered in cosmic and geological models as a potential influence.  Uranium and other heavy elements are formed in supernova and are found across the universe.   The distribution of these elements now needs to also be considered as an important factor in which kinds of reactions can occur in which areas.

The more practical side:

The artificial nature of fission has always been used as an argument against it.   It has been claimed that it produces materials that are not normally encountered and have properties that are different from any pre-existing substance and that the uniqueness of the reaction and its byproducts makes it unpredictable.   It has also been argued that since the sun and other stars are powered by fusion, nuclear fusion is therefore a more perfect, cleaner energy source that we have always lived with, while fission does not have the same kind of appeal.

We now know that this is simply not true.   Fission can and does happen on its own, without human intervention and has so for billions of years.   Fission chain reactions and the byproducts of fission are not alien to earth and their existence did not halt life, but may have facilitated it.  They can exist in the environment without causing catastrophe and always have.   Fission is not unusual and is certainly not a creation of man.   It is a basic reaction, as fundamental as fusion or fire.

We live in a nuclear powered universe.  The energy we experience may have come from nuclear fusion, fission, decay, from the reactions of cosmic rays or even from the subatomic reactions that occurred moments after the big bang.   Nuclear reactions generate all energy, liberating it from the forces that bind all mater together.  These reactions will happen with or without our intervention.

We would be fools to not realize this and use nuclear energy to our own advantage.

This is truly one of the most exciting unmanned space missions in a long time, and perhaps the most exciting to visit mars since exploration of the planet’s surface began in 1978 with Viking 1.   The probe is a rover, somewhat similar in design to the rovers Spirit and Opportunity which proved to be astoundingly long-lived and robust machines.

It’s build on the success of the previous rover missions, but is far more bold and ambitious.  The rover will be physically much larger than the previous rovers and will have considerably greater scientific instrumentation and on board computing power.   The rover will carry extensive analytical instruments.  Like previous rovers it will have an alpha-particle x-ray spectrometer, but will also have a laser-induced breakdown spectroscopy system, along with a host of other scientific instruments for analyzing soil and rock, examining samples and detecting environmental variables like particle radiation, temperature, pressure and light levels.   The rover will have the best camera systems yet taken to mars and will be able to take full motion video, even capturing ten frames per second of high definition video.   With two gigabytes of radiation-hardened storage it will be able to cache thousands of pictures and volumes of scientific data for transmission back to earth.

What makes this all possible and what makes the MSL so much more capable than previous rovers is the source of power.   Spirit and Opportunity were designed to be solar powered.  As we all know, solar cells don’t provide a huge amount of energy on earth, but on mars it’s even less.  Under ideal conditions, the Exploration Rovers could gather .6 kilowatt hours of energy each day from their solar panels.   However, conditions were rarely so good and dust on the panels made the amount of energy the panels provided in a day even less.  This is a severely limiting factor, forcing the rovers to spend considerably more time sitting idle and charging their batteries and making it a necessity that energy be used as frugally as possible.

The Mars Science Laboratory has its own nuclear power source, providing vastly more power, day or night.   It’s not a reactor but a radio thermal generator, powered by the decay of plutonium-238.  The power source will deliver a constant supply of more than 100 watts to the spacecraft.  By mars probe standards, that’s a real lot, especially because it’s continuous.  With a half life of 88 years, it’s likely that the mission will end due to equipment failure before any noticeable reduction in power output occurs as a result of the decay of the plutonium-238 heat source.

Getting enough plutonium-238 to power future missions could be a problem due to lack of capacity to produce it in the US and tightening supplies from Russian producers, but that’s another story.

Despite the astounding science that is provided by interplanetary missions, the use of anything “nuclear” for any purpose is sure to draw some protests.   (Don’t even get me started on how stupid it is to complain about polluting outer space with radiation)  Some of the opponents claim that the material is so dangerous it could cause catastrophe if the rocket exploded or the probe crashed back to earth.  Of course, both because of the design of the RTG and the material used, dispersal is unlikely even in that event, and the worst case would result in only minimal exposure to anyone.  Still, some have tried to stop the launch or at least protest it.

But not many seem to really be buying into it anymore.  In fact, the protests have dwindled down to almost nothing…

Via Florida Today:

Plutonium protests can’t draw a crowd
Don’t expect protesters to turn out in force over the potential safety risks from Saturday’s planned launch of the plutonium-powered Mars rover Curiosity from Cape Canaveral Air Force Station.

Citing everything from apathy to holiday and shopping distractions, those known for staging protests during past launches of plutonium-fueled probes from the Cape and Kennedy Space Center will be no-shows this time around.

An Atlas V rocket carrying the rover and its 10.6 pounds of plutonium-238 is scheduled to launch at 10:02 a.m. Saturday.

“It’s not that we’re not concerned, but folks are so worried about the economy right now it’s hard to drum up support over something that ‘might’ happen,” said Maria Telesca-Whipple, a Rockledge resident who is an organizer with the Global Network Against Weapons & Nuclear Power in Space.

…

Past NASA launches of plutonium-fueled probes, such as New Horizons in 2006, Cassini in 1997, Ulysses in 1990 and Galileo in 1989, have drawn protesters to the Space Coast. All launched without any release of radiation.

But efforts to rally protesters to show up for Saturday’s launch have proved futile, organizers said.

Pax Christi Tampa scheduled a rally two weeks ago at a busy intersection, and “no one showed up,” said John Stewart, who spearheaded the event and has been pushing an opposition movement in Florida since the summer. He’s sent out more than 400 newsletters, handed out flyers on the street and been on radio to warn Floridians. But, thus far, he admits he’s received no feedback.

“Global Network Against Weapons & Nuclear Power in Space.” Wow. I guess they spend most of their time protesting the sun. Dare I suggest that maybe it’s not simply other concerns distracting the public,m but maybe people are actually wising up? Or perhaps the public is impressed by the images and information brought back by space probes and is realizing that these are great achievements of science that should be supported. (I can dream, right?)

I am a little concerned, however.   Excited as this mission makes me, it also leaves me a little worried.   The probe has a long and treacherous trip to mars and must survive a very rough landing.  Despite all the engineering that has gone into it, probes have failed many times and this mission is certainly not a sure thing.   It’s a lot of money and a huge capability being placed on one probe, so I’m sure I’m not the only one holding my breath for it to succeed.   Hopefully this August I’ll be letting out a huge sigh of relief and seeing some amazing pictures get beamed back.

Ionization detectors use a tiny amount of radioactive material, usually amercium-241, to ionize air in a small chamber in the detector.  When smoke particles from a fire enter the detector, they interrupt the ion potential of the air in the chamber, thus tripping the detector.

Photoelectric detectors work by using a tiny light emitting diode, usually infrared and a light detector.  A small gap between the light and the detector allows air to pass between the two.  When smoke particles enter the detector, they obscure the light beam and this triggers the detector.

Recent Opposition to Ionization Detectors:

In recent years there have been some groups that have sprung up claiming that ionization detectors are entirely unreliable and that the use of ionization detectors puts lives in danger due to their failure to adequately detect and warn of fire.   This is often accompanied with claims of some kind of conspiracy between authorities and smoke detector manufacturers to keep this information from the public.   The issue of radioactivity and claims of corruption by the nuclear industry as also been a fixture in the argument.

It may not be that surprising, in the end.  Given the rampant radiophobia that has gripped the world, even the humble smoke detector had to eventually become the subject of fear.

These arguments were used as the basis for an Australian documentary and advocacy project with the absurdly dramatic name “Stop the Children Burning.”

Here is a clip from the film:

In reality, there’s no danger posed by the tiny amount of Am-241 in smoke detectors.  Am-241 produces some low energy gamma rays, but is primarily an alpha emitter.  The material is present in microscopic quantities and is in a form that is non-soluble, chemically stable and not easily absorbed.  It can resist all but the most extreme temperatures, and if the temperature was that high, you’d have worse things to worry about than inhaling a tiny amount of Americium liberated from the detector.  In most cases, the Am-241 is in the form of an oxide or ceramic and is embedded in gold foil that is affixed to a steel disk, usually recessed.   It is specifically designed to make release of the material unlikely.

There is no requirement for special disposal of smoke detectors nor do they require a license to own or sell.  The total radiation exposure during normal operations is negligible and even in the most extreme cases of a release of the embedded material would still be too small for much concern. It has not been “declared fifteen times more dangerous than plutonium.” It is technically about fifteen times more radioactive per unit of mass because the half-life is shorter, but that also means a much smaller amount is needed to produce the same ionization effect than would be needed if plutonium were used.

So which is better?

First, it’s important to realize that neither technology is perfect and in both cases, there will be examples of smoke detectors that did not promptly detect the smoke from a fire, either the convection patterns did not carry enough smoke to the sensor, because the sensor had become blocked by dust or debris or because the level and type of particulates in the smoke was not enough to trigger the alarm.  Both can suffer from a defect or malfunction or neglect to keep working batteries in the unit.   The best way to reduce the likelihood of a failure, with both kinds of detectors is to have multiple detectors in varying locations, each regularly tested and equipped with working batteries.

Advantages of ionization smoke detectors:

• Usually Cheaper - This is not simply insensitive “profits over people.”  Since ionization detectors tend to be cheaper, it’s easier to get more people to buy and install more of them, and programs to distribute them can get more units on a fixed budget and give them to more people than could be done with photoelectric.  Therefore, it is a consideration.
• Batteries tend to last longer – Since the ionization detector does not need to power an internal LED, it uses that much less power and therefore, all things being equal, will have a longer battery life.  This is an important feature, because many smoke detectors have dead batteries, and longer battery life reduces the liklihood that the battery will go dead before the owner thinks to replace it.   There are some ionization smoke detectors avaliable that are sealed, with a perminantly-installed battery and a ten year life.   You won’t find that in a photoelectric detector.
• Much better at detecting fires that do not produce thick visible smoke – When it comes to fast-moving fires and open flames, the ionization smoke detector wins over the photoelectric detector hands down.   These kind of fires don’t produce the thick visible smoke that smouldering flames produce.  Rather they produce small particulates that are easily detected by ionization smoke detectors and not easily detected by photoelectric smoke detectors.  If you set something on fire and it burns with full, fast-moving flames, the ionization smoke detector will almost always give you a faster warning than the photoelectric, although both will usually detect it once high enough concentrations are reached.

Advantages of photoelectric smoke detectors:

• Fewer False Alarms – Photoelectric detectors are less likely to be triggered by things like steam clouds, which might be produced by a shower or a kettle or the kind of smoke produced by cooking.  This is an important consideration, especially when the detector is placed somewhere where such events are common, such as near a kitchen or outside the door of a bathroom.  Frequent false-alarms as a result of something like steam can lead to the smoke detector being disconnected or disabled by annoyed residents and thus providing no protection.
• Better at detecting fires that produce a lot of thick visible smoke - While the ionization detector preforms better in detecting the smoke of open, fast-moving flames, the photoelectric detector tends to be more sensitive to the kind of thick, sooty smoke that would be produced by a smouldering fire.   Many home fires start off this way before progressing to a large rapidly-moving flame.   For example, if someone left a cigarette on a sofa or bed and it started a slowly burning, smouldering fire that produced a lot of thick smoke, the photoelectric detector would tend to detect it before the ionization detector. This could not only be life-saving but also property-saving, since many large fires start off as relatively small smoldering fires, which, if caught before they erupt in flames, could be put out relatively easily.
• Less affected by high air flow - In areas where there is high air flow, such as if a detector were installed inside a duct, photoelectric detectors tend to work better than ionization detectors, even for fires that would normally be detected faster by ionization detectors.  The rapid flow of air can prevent the particles from interrupting the potential in the chamber of an ionization detector, but won’t do much to reduce the sensitivity of a photoelectric detector.

Which you should get:

If I had to choose one or the other, I think I would tend to lean toward the ionization detector, because it seems to be the one that is the fastest to detect the fires that have the least time to escape and which produce the kind of smoke you are less prone to notice on your own anyway. However, all things considered, there are certainly circumstances where one could make the case for the photoelectric detector being the better of the two.

Both detector types work adequately well in most situations and conform to all standards for fire protection. If you have only ionization detectors or only photoelectric detectors, you would generally be judged to be in compliance with good fire protection practices, although you could do a bit better.

The national fire protection association along with most other major fire safety bodies recommends the use of both types of detectors for maximum protection.

Really, you should have both. There’s no need to choose one or the other. Both are quite affordable and easily available. Today there are many units which have dual sensors, detecting smoke by the use of both ionization and photoelectric effects. Since each detector type is undoubtedly better at detecting certain kinds of fires, the type which work in both ways are going to have the highest likelihood of providing ample warning, regardless of the fire type. The only time that a detector with only one sensor type might be preferable is in locations prone to false alarms. For example, if you are going to install a detector in your kitchen, near the stove, a detector that only has a photoelectric sensor might be preferable.

There are other considerations, of course, that go into achieving good fire safety. Smoke detectors should be installed on every level of a home, including the basement. Placement is also important. Detectors should be installed in relatively open areas, away from interior corners or sheltered areas that might not get good air flow. They should not be installed near ceiling fans or ducts. Smoke detectors are best installed on ceilings or can be on the upper surface of a wall, near the ceiling.

It is recommended that detectors be installed near bedrooms. Multiple detectors should be used if the bedrooms are far apart. Good central areas for installation include the hallways near bedrooms, at the top and bottom of stairs and in large rooms. It is also a good idea to have smoke detectors located in utility closets or rooms and around equipment like water heaters, furnaces, electrical boxes or anywhere else where a system failure could cause fire.

Ideally, smoke detectors should be wired together so that if one detects smoke, a whole-house alarm is triggered. This may even be required for new construction in some areas. Unfortunately, while this is the most ideal solution, it’s usually not practical for per-existing structures. In the later case, it’s important to assure the alarms are loud enough to be easily heard, even from another part of the house and through closed doors.

Batteries should be checked regularly and replaced when necessary.  Most detectors have a feature which allows for them to be tested to assure that the battery is not dead and that the audible alarm works.  However, this does not verify that the detector itself is working properly and is not blocked by dust or otherwise has lost sensitivity.  There are products available that can be used to test the ability of the detector to respond to smoke.  One of these simulated smoke products is shown to the right.

Some smoke detectors have a feature that causes them to beep intermittently when the battery begins to reach the end of its life.  It can be a little annoying, but it does assure you won’t forget about the batteries.  However, if you take one down to stop the annoying periodic beep, be sure to actually replace the battery and put it back up.   The best way of powering smoke detectors is to use central wiring with the battery being primarily a backup, in case the power goes out or the fire damages the home’s wiring.   Unfortunately, as with centrally wired detectors, this option is not usually viable for per-existing construction.

It’s also a good idea to have a carbon monoxide detector, which often is combined with a smoke detector.  Carbon monoxide is a colorless, odorless gas that can easily kill without warning.  Carbon monoxide is produced by combustion and can enter a house due to malfunctions of hot water heaters, heating systems or if a car is started in an attached garage with the doors closed, as can happen if a remote car starter is triggered accidentally.  At least 170 people die of carbon monoxide poisoning every year in the US alone.

Conclusion:

Both types of detectors work, although each works better in different circumstances.  You’re best off having both and they should always be properly installed and checked.  However, both types may fail to give adequate warning in all circumstances and therefore they should not be considered a substitute for basic vigilance and fire safety measures, like proper electrical wiring, and keeping potential fuel sources away from potential sources of ignition.

Ionization detectors are not inherently unsafe or flawed in any way.  The greatest danger in terms of detector failure comes from improper installation or maintenance of the detector, not because it happens to be an ionization type detector.

The AC Gilbert set was certainly the most elaborate and complete atomic energy set sold, but it was not the only one. The American Basic Science Club produced a similar lab set around 1960, and Chemcraft produced a lab set in the late 1940’s to early 1950’s. In the 1950’s, some Chemcraft chemistry sets also included radioactive materials and experiments that could be done with radiation.

I have always thought that these sets were an incredibly good idea and a really excellent way to acquaint young people with the basics of radioactivity and, importantly, demonstrate that radiation is common and not something to be feared. These lab sets were extremely safe. The amount of radioactive materials present in the experimental sources was microscopic and not at all dangerous. The uranium ore or uranium compounds included are not a radiological hazard and are only a toxicity hazard if they are ground up and snorted or otherwise inhaled, and even then, are less toxic than an equivalent quantity of something like lead.

There’s really no better way to get a kid acquainted with science than to actually do some hands-on activities. They improve understanding and retention and allow them to participate directly in making exciting observations. Anyone lucky enough to have had one of these labs as a child probably grew up with a healthy understanding (and not fear) of radioactivity.

Sadly, the world has changed since the early 1950’s, and today most people seem to run around with rampant radiophobia. If something is “radioactive” (which nearly everything is) then it’s seen as being of the highest danger. Nothing is believed to be more environmentally destructive, more dangerous to health, more disastrous, more hazardous and more terrifying than radiation. The idea that at one time children were allowed to learn with materials that produce radiation significantly above background levels fills some with horror and others laugh at just how stupid everyone must have been fifty years ago.

Here’s some of the things that have been said about the AC Gilbert Atomic Lab:

From the Daily Grind:

World’s Most Dangerous Toys: Gilbert U-238 Atomic Energy Lab
If you thought choking hazards in toys were bad then spare a thought for American kids in the early 50′s.

Introducing the Gilbert U-238 Atomic Energy Laboratory. This toy lab set was produced by Alfred Carlton Gilbert between 1950 and 1951 and sold for $49.50US (which is equivalent to about $380 – $400US dollars today). So if you were lucky enough to have well off parents back in the day you may well have been ‘lucky’ enough to get your hands on this radioactive fun set.

From Liveleak:

Very bad toys: Atomic Energy Lab usa ca. 1960
t’s unclear what effects the Uranium-bearing ores might have had on those few lucky children who received the set, but exposure to the same isotope
U-238 has been linked to Gulf War syndrome, cancer, leukemia, and lymphoma, among other serious ailments. Even more uncertain is the longterm impact of being raised by the kind of nerds who would give their kid an Atomic Energy Lab.

From Cracked

The 8 Most Wildly Irresponsible Vintage Toys
#1. Atomic Energy Lab

As a kid, did you ever swallow or at least put in your mouth a small piece of a toy or play set? Did you grow an extra arm because of it? No? Then you probably didn’t have the Atomic Energy Lab.

You see, there was a different approach to nuclear power in the ’50s and early ’60s — atomic energy was our friend and the way of the future, and it would never do anything to hurt us. However, it’s still hard to believe that anyone would entrust kids with radioactive material (even in small doses).

Yet, the Atomic Energy Lab kit produced by the American Basic Science Club came with real samples of uranium (which is radioactive) and radium (which is a million times more radioactive than uranium). Since the mere presence of radioactive material in a children’s product clearly wasn’t insane enough, some of the experiments detailed in the manual also required kids to handle blocks of dry ice. Dry ice, by the way, has a temperature of minus 109.3 degrees Fahrenheit, and it’s recommended that it only be handled while wearing gloves (none were included).

Okay, they’ve got a point about the dry ice, although it’s reasonably safe to handle with basic precautions. Still, I’m downright offended by the way that people completely ignorant of what radiation is or the dangers can sit there and smugly dismiss the idea of a radiation experiment set as being insane. It’s often ranked the most dangerous toy of all time, but in fact, it’s not dangerous at all for any normal 12 year old to learn from a microscopic amount of a radioisotope or a little bit of uranium ore, which they may well have sitting in their backyard anyway.

I’ll go one further:  Not only do I think this was a great idea and a very positive learning experience, I also think that there has never been a better time for something like a radiation and nuclear energy lab set!  Having a set that had a good variety of experiments would be fairly expensive but not unaffordable.  It would be targeted at ages 12 to adult and could also be something science departments at schools might be interested in.

I’m seriously considering doing it!  I’ll take the flack for selling kids a horrible cancer-causing evil material if I have to, because somebody has got to do it, and if I get enough interest I may very well start putting some kits together.

Things to include:

1. A Geiger counter - this is undoubtedly the most important part of the lab, but also one of the most problematic.  The cost could easily drive the price of the set way too high if a high quality Geiger counter is used. Detecting alpha particles would be great as a way of teaching of the different types of radiation but most inexpensive Geiger-Muller tubes can only detect gamma and high energy beta. Detecting alpha particles requires a very thin window, usually made of mica. That tends to drive the price up, so alpha detection may need to be omitted. Ideally the Geiger counter should connect to a computer to expand the types of experiments possible and allow data logging. This may drive the price up too high, however.
2. A set of shielding materials – One of the most fundamental lessons is understanding the nature of shielding, so a series of materials would be provided.  These would include Mylar, thin plastic, thicker plastic, metal sheets and lead foil, possibly coated in plastic to relieve fears of lead poisoning.
3. A spinthescope or scintillation screen material – This would provide one alternative for detecting alpha particles that the geiger counter can’t.  It also is a fun and interesting experiment to view the radiation-created flashes of light in a darkened room.
4. A cloud chamber - An absolute must for any basic nuclear energy lab kit.   Simple cloud chamber kits are already available
5. An electroscope – To demonstrate the ionizing effects of radiation and the earliest types of detectors
6. High power rare earth magnets - to demonstrate that particle radiation can be effected by magnetic fields.
7. A guide to identifying radioactive minerals – basically a book with types of uranium and thorium ore shown with their geographic distribution and general characteristics shown.
8. An experiment guidebook – A list of the different experiments possible

Included radioactive sources:

1. A sample or multiple samples of uranium ore
2. Uranium marbles - They’re cheap and easy enough to obtain and provide a safe base level for some experiments
3. License Exempt Sealed Sources – The company Spectrum Techniques manufactures samples of various radioactive substances, including thalium-204, strontium-90, cesium-137, lead-210 and polonium-210 that are available in either needle sources (used primarily for cloud chambers) or sealed in plastic discs.   The sources are approved for sale and possession without a license because the actual amount of material is tiny.   They run from about fifty to eighty US dollars each.  Since Po-210 has a very short halflife, including it with a cloud chamber or other product presents a problem, so Spectrum Techniques offers a coupon that can be included with such products and then mailed in to receive the sample once the consumer gets the product.

Possible Experiments:

1. Measuring radiation – Basic measurements with the Geiger counter, measuring various sources.
2. Measuring radiation in your environment – Use the Geiger counter to measure the baseline background in various areas and record how it changes by time of day.  Look for radioactive items.   What common items emit radiation and how much?    Go on a hunt in an antique store, your kitchen or somewhere else and see what you can find.
3. Prospecting - Using the Geiger counter and the guide to minerals, what types of ore can you find?
4. Shielding Experiment – Observe how various types of radiation can be shielded and attenuated.  Use the shielding to help determine the type of radiation being measured.
5. Cloud Chamber Experiments – Observe particle paths in the cloud chamber using various sources.  Also see how magnets can alter the paths of particles.
6. Spinthescope Experiments – Observe alpha radiation with the spinthescope and also use it to help determine what kind of radiation is being measured.
7. Find a hidden source – Have a friend hide one of the radioactive sources in a room and use the Geiger counter to find it.

Of course these experiments would have more descriptions and some of them might even be designed to dispel myths, for example, those who live near a nuclear power plant would be encouraged to measure radiation at various distances and plot the levels.  Also, cell phones could be on the list of items to examine to show they do not give off ionizing radiation.

Cost:

I’d like to keep the kit affordable, ideally, about 300 US dollars as the top end of what it should cost, but realistically, it may turn out to be more.  I’d consider 500 USD to be the absolute maximum that could be charged without making the set far too expensive for most people to afford.    I’m more than happy to put such a kit together at almost no profit.   To be perfectly fair, I think it’s reasonable that I would make a small amount of money (perhaps $25 or so) over the cost of the materials, because I’m going to incur other miscellaneous expenses like printer toner, paper, phone calls and my time spent putting such a kit together.   However, my primary goal is not to make money off of this so much as to produce an educational experiment kit. Most of the items included would not cost much.

The marbles, ore and shielding material could be acquired for under $50 and the cloud chamber for not much more.   United Nuclear sells a spinthariscope for $35.  It would probably be possible to get it a bit cheaper if such an item was purchased in bulk. Other expenses would include the packaging and instructions.   The cost before the sealed sources and Geiger counter is therefore going to be about $100.

The sealed sources are going to be the first big expense.   A complete set that includes a beta emitter, a gamma emitter and an alpha emitter is going to cost about $150.   I’m a little split on whether to include Po-210.  On one hand it’s the only exclusive alpha emitter that could be included, but on the other, it’s rather short lived.   The alternative would be to include lead-210 in equilibrium with polonium-210, which would produce both beta and alpha particles.   Adding another gamma emitter to demonstrate the differences in energy levels would be great too, but for a real complete set of radioisotopes, it starts to look more like $175-$200.  It’s possible it could be less if they are bought in bulk. Therefore, the kit is already reaching the $300 mark before the most important component, the Geiger counter is added.

Choosing exactly what Geiger counter to include will be a challenge.   I can definitely acquire Geiger counters that fit all the necessary criteria and are inexpensive, but generally those are units I’d get surplus or second hand, and thus are each different.   That won’t work here.  What is needed is a standard Geiger counter that will be the same for each Set.

The Russian Company Quartex makes a series of Geiger-Muller detectors that are fairly cheap and very simple to use.  Unfortunately, these units have some major drawbacks.  For one thing, they only measure gamma radiation and hard beta radiation.  That might be acceptable if not for the fact that they also only give readings in dose equivalent, not in counts per minute.  Since the point of the set is understanding how radiation is detected and measured, the more basic unit of CPM is preferable.

Still, it is a complete radiation detector in a nice, small and simple handheld unit.   It may be worth talking to the company to find out if it would be possible to make the one small modification of adding a counts per minute or counts per second reading.

Another option would be to build a GM detector-counter.  The Electronics Goldmine has a Geiger-Muller driver kit, which includes the high voltage supply and and detection circuitry for $30.  That price would be tough to beat by acquiring the components individually, and it has the big advantage of having a per-fabricated circuit board, which would be expensive to have manufactured and time consuming to fabricate individually.   The unit still needs an enclosure, battery holder and switch, but that should be obtainable for about ten US dollars.  The kit does not include a meter movement, so that will need to be added too.  An analog meter would need to have some kind of range switch (to allow for ranges such as 0-100 cpm, 0-1000 etc), which would complicate construction a bit.   There is a digital meter adapter available for about $60, which would work nicely and also adds the ability to hook the unit up to a PC.   The most expensive part of the counter will be the tube.  A suitable, although very small tube could be bought for about $60 each.   This tube would be sensitive to alpha, but given the small size, it would not work very well for general survey work.    All in all, the cost of this geiger counter, including shipping and expenses like solder and wire looks to be about $175, resulting in a total cost of the set of close to $500.

Another option would be to use the venerable CDV-700 as the basis for the detector.   The CDV-700 is a Geiger counter manufactured for the US government during the Cold War.  It was standard issue for fallout shelters. Tens of thousands were manufactured.   Production ended in the 1970’s and since then, many have been sold off as surplus.   It’s about the cheapest Geiger counter that can be purchased, often available for about $50 from a surplus dealer and sometimes less if bought in bulk.  It comes with a small check-source mounted on the side.   This is often depleted uranium but occasionally may be a sealed radium source.  It would definitely be a nice bonus to have an extra source included.

Unfortunately, the CDV-700 has a number of major drawbacks.   For one thing, it will be important to find the right version of the unit.  It was produced by a number of manufacturers and went through a few design changes over the course of its production.   Some early models use high voltage batteries, so these should be avoided as the batteries are no longer widely available.  Another problem is that many CDV-700’s sold surplus do not work, as they have spent years in storage in damp bomb shelters and were not maintained.   Repair is usually fairly easy, as long as they are in good physical shape and not rusted out or otherwise physically damaged.

Assuming the counter is in good condition, it will still need a few modifications.   For one, the headphone connector is a rather obscure fitting known as a “Single button microphone plug.”  These are not found on many devices anymore and would only allow the original headphones to be used.   Replacing it with a more modern 1/8 or 1/4 inch plug will both allow for modern headphones to be used and allow the unit to be easily hooked up to the sound card on a computer so that it can be calibrated and data logged using available Geiger counter software.   It would also be worthwhile to replace some of the more failure-prone electronics with modern versions that are also more efficient and produce less RF noise.   Finally, a reasonably easy addition would be to add a small amplified speaker so that headphones would not be required for listening.  A speaker with a switch or knob would require drilling in the case, but would not be terribly expensive.  Since the meter would need to be taken apart anyway, it would be worthwhile to paint it to make it look more like a scientific instrument and less like a piece of emergency equipment. All in all, about fifty dollars invested in the internals would produce a very reasonable meter.

That does still leave one problem, however: the probe.   The CDV-700 comes with a Geiger-Muller tube that was originally intended for use after a nuclear war.  It only detects gamma radiation and relatively high energy beta particles.  Even as a gamma detector, it’s not terribly sensitive and thus leaves some to be desired for surveying relatively low background levels.  The probe on the CDV-700 is permanently attached to the unit, but that is relatively easily solved by disconnecting it and adding a BNC connector to the meter and to the end of the probe attachment, thus allowing the original probe or another probe to be used.

The next problem is finding a suitable alpha-sensitive probe to include.   This site has a surplus alpha-sensitive end window tube for only 37.95 plus shipping.  It would be fairly easy to make a probe out of it by using a small piece of PVC pipe with one end open to hold the probe and a BNC connector and cable to connect it to the modified CDV-700.   The only question is whether the tube is available in large enough quantity to make a reasonable number of lab sets.  If not, there may be other probes that can be acquired as surplus.

This approach seems to end up being the most favorable, as it would provide two probes for different types of use and would also give the option to add more probes in the future, possibly even including scintillation probes or other types of detectors.

In the end, the CDV-700 option with modifications and an additional probe seems to be the best one.

So while the $300 price tag seems unrealistic, it appears that a $500 price should be possible for a very well equipped set with an excellent Geiger counter, expandability, a good assortment of sources and a wide range of possible experiments.

Other considerations:

Many of the readers of this blog are from outside the United States.  Unfortunately that could present some problems for shipping radioactive sources, even those small enough not to require a license.   Simply being of very low quantity is not enough to make the sources legal – they generally must also be inspected and approved by the local regulatory body for radioactive substances, although this varies from country to country.   I’m told that shipping to Canada should be just fine and some countries in Europe are probably okay, although each would have to be individually verified.

Other countries may allow the sources but have restrictions on just who can import and sell them.  Spectrum Techniques has a worldwide network of affiliates and distributors.  In some cases, it may be necessary to sell the set without the actual sources and instead have them shipped separately from a domestic distributor in the country of the purchaser.

Interested? It’s expensive, admittedly. Perhaps I could come up with a partial lab or one that could be bought in pieces. I’m still looking into the possibilities. I’m not going to say that I’m definitely going to go for it, but I might. If I get enough interest I may go for it and start putting some of these lab sets together.