Stories like this really just grind my gears, because the way it is portrayed in the media is simply false.   If you read any of the reports about the recent extension of a moratorium on mining (uranium mining included) in the Grand Canyon area, you’d think that the big bad uranium mining industry was hell bent on destroying one of the world’s natural wonders and was only stopped by the Obama Administration from doing so.

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”.

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Although the winter for much of North America has been mild this season, in Alaska it has been extremely harsh.  While those who live in the more remote parts of Alaska are used to dealing with the extremes of nature, this year they are facing the prospect of being cut off from vital supplies of fuel due to the extent of ocean icing and the harsh weather that has made even airlifting of fuel problematic.   This is not the first time these settlements have faced these kind of fuel problems, and it’s not likely to be the last.   In the past, there have been close calls and times when distant Alaskans have been left without fuel for periods of time.  Yet each time this happens, there is always the possibility that remote villages will suffer or even lose lives.

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.

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Okay, I admit it.  I’ve been at work in a circumstance where I should have been writing code or responding to e-mails and I may have hit up Facebook or Google News.  Sometimes I had a half-assed excuse to it, like that the weather was bad and I needed to know if there were any impending weather emergencies that might force the business to close early.  I might also say justify my Facebook surfing as “exploring the possibilities of social marketing.”   The fact of the matter is that I was slacking a little from time to time.   Who amongst us hasn’t?

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.

When spacecraft are sent to explore the inner solar system, solar cells are usually the choice to provide power.  However, when venturing out past the orbit of mars, the intensity of sunlight available makes it increasingly difficult to obtain sufficient amounts of power.  Past Jupiter, it’s virtually impossible to power a space probe with solar cells as they would need to be enormous to gather enough sunlight.   Even within the inner solar system, where sunlight is reasonably intense, solar cells provide limited energy for probes that explore the surface of planets, such as the mars exploration rovers.   Sunlight is also problematic for places like the earth’s moon, where spacecraft would sit in complete darkness for days.

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.

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The item shown bellow is a tritium-containing radiolumonescent key chain.  It’s basically a small glass vial containing radioactive tritium gas and coated with a phosphorescent compound and placed in a clear plastic case.   Tritium is a weak beta emitter with a half life of 12.3 years.  Because the beta particles are very low in energy, they are entirely blocked by the glass and are not detectable on the surface of the key chain.  The beta particles ionize the phosphorescent compound and produce a steady glow, most often in green (the brightest and most visible color) but also available in other colors.  Because of the 12.3 year half life of tritium, these key chains can be used for several years before there’s any noticeable reduction in brightness.

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.

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An interesting story has recent come out about research at the Lawrence Berkley National Laboratory has been making the rounds.   It seems some studies relating to the cellular-level effects of ionizing radiation have found the effect is….. GASP…. not linear and directly proportional to dose level.

Via HealthCanal:

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When nuclear fission was first discovered in the laboratory, in 1938, it was seen as a relatively strange reaction, resulting from humans taking a sample of the heaviest known element and shooting artificially-generated neutrons at it until some of the atoms absorbed a neutron and split.   While the experiment provided enormous insight into the nature of atoms and helped provide early confirmation of Einstein’s Theory of Relativity, by demonstrating the release of energy from an observable change in atomic mass, it was regarded as something that occurred in the laboratory.

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.

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The big Atlas rocket has rolled out of the Vertical Integration Facility and is now on the launch pad, payload checked and stowed and systems being checked.  Tomorrow (the 26th of November) it will lift off with the Mars Science Laboratory, a new rover bound for the red planet with plans to land on the red planet in August of 2012.

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…

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There are two primary types of smoke detectors: ionization and photoelectric.  Ionization smoke detectors are the most common type and have been around the longest.   Photoelectric detectors have not been commonplace until more recently and are still generally less common than ionization detectors.

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.

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Between 1949 and 1951, the company Ac Gilbert produced and sold the “Atomic Energy Lab,” a kit of nuclear and radiation-related experiments intended for use by children in the same way that chemistry sets are used.   The kit included a sample of uranium-238, a Geiger counter, cloud chamber, spinthariscope and some other items used for educational experiments with radiation.  It also included at least three small radioactive sources.   It was modestly successful, likely due to the rather steep price of the set – $50, which would be equivalent to about $460 today.  (about 325 EUR, 285 GBP, 430 AUD)

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.

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