Do our nuclear weapons work?

November 23rd, 2012
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The answer, it turns out is “probably” or “we’re pretty sure they do.” or “Almost for sure, most of them should.”

That’s right.  We’re not entirely sure, and as time goes on we’re becoming less sure.   That’s because we don’t test them and haven’t done so for two decades.

How it was and how we got here:

A nuclear weapon is a very complex piece of engineering and physics.  There are many parts that have to work properly for the weapon to actually detonate.   The core must implode in a manner that results in the correct final geometry.  It must undergo fission before it is blown apart, sometimes requiring additional neutrons be provided by a pulsed neutron generator or by boosting with a small amount of fusion.  In hydrogen bombs, energy from the primary must be channeled into the secondary and produce fusion.   The time tolerances involved are less than nanoseconds.

For this reason, nuclear weapon designs were initially always tested at full scale, in prototype devices that would then become production weapons.  The first tests were conducted in the atmosphere.  Hundreds of such tests, some of multiple megatons were conducted by the United States and Soviet Union in the 1940′s, 1950′s and 1960′s.   These tests had multiple purposes.  In addition to validating the viability of the weapons designs, they were used to better understand the physics involved, with data collected to help guide future weapons design.  Tests were also used to determine the effects of weapons on structures, aiding in the design of nuclear-resistant structures, communications systems and weapons platforms.

In 1963 the United States and Soviet Union signed the Partial Test Ban Treaty.  The treaty ended the testing of nuclear devices in the atmosphere, underwater or outer space by the signing parties.  After 1963, all US and Soviet tests would take place underground, in shafts designed to completely contain the explosions and prevent any fallout from entering the atmosphere.    For the most part, this was successful, although there were occasional minor leaks and at least one major breach of containment due to an unmapped fissure in 1970.  France and China continued to conduct atmospheric testing, having not been party to the 1963 treaty.  The last atmospheric nuclear test was conducted by China in 1980.  Since that time, all tests have been underground.

By the late 1960′s, the superpowers had generally ended the practice of testing nuclear weapons at their full yield.   Having acquired a much better understanding of the physics and engineering behind nuclear weapons, it was no longer considered necessary to test the secondary stages of nuclear weapons at their full yield.   Testing the fission primaries, with either no secondary component, or a greatly reduced secondary yield provided ample data on the reliability of the weapon design.

The only exception to this was the rare circumstance where a new type of weapon was developed, with a vastly different design than previous weapons.  The 1971 Cannikin test was one example of a high yield weapon tested underground. At five megatons, the exceptional yield of the test device required extreme measures be taken to contain the blast. The test was conducted at the bottom of a 1.8 kilometer deep shaft, drilled through solid rock on a remote island off the coast of Alaska. The weapon tested was the W71, a highly unique warhead designed for the Spartan anti-ballistic missile system. The new warhead was designed to produce an extremely high x-ray and neutron flux and to operate in the extreme environment of outer space, possibly being subjected to radiation from other nuclear explosions. Given these special design criteria, it was determined that a full scale test of the system was necessary.

In 1974, the US and Soviet Union signed the Threshold Test Ban Treaty, limiting nuclear tests to a maximum of 150 kilotons. By the time the treaty was signed, it was no longer necessary to test weapons at their full design yield, so the treaty was largely symbolic. Since larger tests require more complex and extensive containment measures, and because they were no longer necessary, both countries had generally abandoned large tests by that time. Although other nuclear powers were not party to the treaty, by the 1970′s, full yield weapons testing was no longer necessary for established nuclear powers.

The United States and Soviet Union continued to conduct nuclear tests, mostly with yields of a few kilotons, throughout the 1980′s. France, China and the UK also conducted nuclear tests through the 1980s and into the early 1990′s.

The End of Nuclear Tests (for established nuclear powers):

The Soviet Union conducted its last underground nuclear test in 1990. After the fall of the USSR, the Russian Federation did not conduct any further tests, although it did make preparations for tests which were ultimately suspended of canceled. The United States conducted its last nuclear test in 1992, before suspending the testing program. China and France continued until 1996. In the 1990′s, political pressure began to increase dramatically on countries to end nuclear testing completely. At present, Russia, the United States, China, France and the UK have completely shelved their nuclear test programs since the mid 1990′s, although the assets for nuclear testing may remain on standby.

In 1996 the Comprehensive Test Ban Treaty was introduced to the United Nations. It would end all nuclear testing of any kind by the parties of the treaty. Although the United States signed the treaty, it was never ratified by the US Congress,it is therefore officially unrecognized by the US until ratified. It also has not been signed by all nuclear powers in the world, and as such, it has not come into force.

None the less, given the amount of time that has passed since nuclear tests have been conducted by the major nuclear powers and the political pressure associated with testing, there are no plans to resume nuclear testing by the US, Russia, France or the UK. India and Pakistan conducted tests as recently as 1998 and have indicated that they may conduct more. North Korea conducted the most recent nuclear test in 2009.

The dangers of not testing weapons:

All of the nuclear weapons in the inventory of the United States have been extensively tested.  That’s also true for Russia, the UK, France and the other major nuclear powers. That is definitely a good thing, because despite the extensive knowledge and experience the US has with nuclear weapons design, building a new weapon without extensive testing can result in some very unwelcome surprises.   The extremely high tolerances and complex physics and engineering involved in weapons design makes it difficult to ever be absolutely sure they work without testing.

In the early 1960′s, the United States was at the top of its game when it came to nuclear weapons design, and was highly confident in the ability of scientists and engineers to design effective and reliable nuclear weapons.   However, in the early 1960′s, both the Soviet Union and the United States suspended most nuclear testing for a period of about two and a half years, as they engaged in diplomacy over testing requirements.  While this was not an officially sanctioned ban, it did result in a brief de facto nuclear testing moratorium.

When the United States began testing again, in the mid 1960′s, it was discovered that the two weapons primaries, which had since become the most important component of the US strategic nuclear force had a major reliability.  Both the Python and Tsetse primaries reportedly did not function as expected during testing.   The extent and nature of the reliability problem remains classified, but it is known that hundreds or thousands of weapons had to be pulled from service and modified.

In the case of weapons that have been fully tested, it’s not entirely uncommon for surprises during the testing phase.  During testing of the W47 warhead, it was discovered that the design had the potential to accidentally detonate, even if the core was only partially imploded, as might happen in an accident.  As a result, additional safing mechanisms were added to the production version of the warhead.   Later tests, however, revealed that the safing mechanism employed could reduce the reliability of the warhead, eventually leading to its retirement from the stockpile.   Tests also revealed unexpected reliability issues with the W52 and W45 nuclear warheads.

It should be noted that the extent to which unexpected results have occurred during nuclear tests, even in relatively mature designs, is not publicly known.   In most circumstances, the precise results from nuclear tests remains top secret.  What we do know is that they have occurred in at least a few noteworthy cases.

Reliability problems are not confined to older weapons designs.  The W76, which is a mainstay of the US submarine-launched nuclear missile force, has been criticized for containing a possible design flaw that could, at least in some circumstances, result in a failure to detonate or a dramatically reduced yield.   Whether these concerns are valid is impossible to know for certain without further testing of the warhead.

There are, however, plans to design and construct a nuclear weapon with absolutely no testing whatsoever.   The Reliable Replacement Warhead was proposed as the first new American nuclear weapon since the late 1980′s.   It was intended to be a post-Cold War design, replacing older warheads with one that would have an extended reliable shelf-life, minimal maintenance and enhanced safety.   Such a warhead would fulfill the need for a long term stockpile with minimal upkeep and greater reliability.   Some designs were to be based on existing, tested warheads, but concerns were raised about the use of any warhead whose final design would never be the subject of any testing.   In 2009 funding was cut and the program shelved, but the possible need for a modernized warhead continues to be debated.

The Aging Stockpile:

At present, the United States relies on existing weapons as the backbone of the nuclear deterrent.  Some, like the B61, are more than forty years old.  During this time period, they have received periodic upgrades of electronics and components like chemical explosives, batteries and tritium supplies have been replaced due to age.  However, the weapons cores are original.

This presents a problem.   Nuclear weapons have extremely high design tolerances, and this is especially true for the advanced designs of most active US nuclear weapons.  Modern nuclear weapons use a minimal amount of explosive combined with air lenses and specially shaped cavities to rapidly and precisely implode a plutonium core.  Some also use neutron generators to speed the initiation of the fission reaction as the core implodes.   The tolerances of these systems are in the nanoseconds, and if the core does not implode with perfect symmetry or if the material does not come together fast enough, it will not function properly.

Making a core that will preform properly is made more difficult by the nature of plutonium.  Plutonium, as it turns out, has some of the most undesirable characteristics of any metal.  It’s extremely hard, brittle and difficult to machine.  Plutonium is also pyrophoric, auto-igniting in some circumstances. Plutonium is known to form a complex microcrystalline structure that can be prone to cleavage. In fact, the properties of plutonium are so poor that pure plutonium is not used for weapons cores. Rather, an alloy, composed mostly of plutonium, but also containing small amounts of gallium and possibly other materials is used to provide acceptable physical properties.

But plutonium has another property that is especially worrisome when testing is not being conducted.  Because plutonium is radioactive and produces strong alpha emissions, it will, over time, self-irradiate and produce changes to the structure of a plutonium core.  Over time, some of the alpha particles produced by the decay of plutonium become entrapped in the crystalline structure of the material.  These form tiny pockets of helium gas and may have the effect of cleaving the material, reducing strength or changing the physical properties.  Some swelling can occur, potentially changing the cores precise geometry.   The plutonium-gallium alloy also tends to separate, with gallium grains migrating to the center of the core, leaving a gallium-depleted region with potentially problematic physical properties.

The problem is by no means unique to the United States.  Although less public information is available on the condition of Russia’s nuclear warheads, the average of the core material is believed to be much older than those of American weapons.   The material has also been subject to considerably less testing and may not be as durable as American plutonium alloys.  The average age of the weapons held by China, India and Pakistan is less, but the weapons designs have not been subject to as extensive testing as US or Russian weapons.

So how do we know this is not reducing the reliability of the weapons?

The most direct and reliable way of knowing is to periodically test the weapons.  It’s otherwise quite difficult to know for sure, given that we have only a half-century of experience with plutonium.   Also, as different weapons have different core designs, different isotopic ratios of plutonium and different ages, it’s hard to be sure that all design types work, just because one did.   As the cores of weapons age, the certainty that they will preform as expected is reduced.

There is, however, one way of assuring weapons are effective, even if the aging plutonium is not tested.  The plutonium pits could simply be re-smelted into new pits, remoulded to the original design criteria.   Doing so would eliminate any microscopic flaws in the structure and redistribute the material throughout the cores.  Unfortunately, the US does not have the capacity to do this.  The Rocky Flats Plant, where plutonium cores were fabricated ended production of weapons in 1989. Today, the hot cells, specialized furnaces and other equipment needed for smelting plutonium exist in only small numbers at a few national laboratories.   While it’s possible that a few cores a year could be re-fabricated, the US lacks the ability to restart large scale core smelting and fabrication without major upgrades to equipment.

As such, the US has perused a program of “Stockpile Stewardship” that involves attempting to assess and maintain the reliability of nuclear weapons without any actual tests.

Some of these include:

Computer simulations - Computer simulations have become a mainstay of the current no-test nuclear weapon stewardship program. Computer calculations are used to predict how the physical properties of plutonium may change over time, how these properties may effect the operation of weapons and also to evaluate weapons designs and basic weapons physics. The calculations required to preform simulations of these processes are extremely complex. As a result, some of the largest and most powerful supercomputers ever built are used primarily for this purpose.As of this article’s writing, the world’s two fastest supercomputers are located at the Lawrence Livermore National Laboratory and the Oak Ridge National Laboratory and are used primarily for nuclear weapons-related calculations and simulations.

Gun-based Materials Shock Tests – The properties of nuclear materials, most especially plutonium and how they respond to rapid physical shocks, similar in effect to the types of forces during a weapon pit implosion are simulated at a series of facilities using specialized high-velocity gun systems.  These are regarded as “subcritical tests” as they use actual weapon material but in quantities too small to produce a fission chain reaction.   Facilities include the Lawrence Livermore National Laboratory’s Contained Firing Facility and Joint Actinide Shock Physics Experimental Research located at the Nevada National Security Site (formerly known as the Nevada Test Site.)

Hydrodynamic Testing - Another form of subcritical materials testing, hydrodynamic testing involves subjecting nuclear materials and core mockups to extreme hydrodynamic shock, simulating the implosion that occurs when a weapon detonates. The implosion that occurs during the tests are recorded at extremely high speed through the use of powerful pulsed x-ray generators, which allow for the interior of the cores to be imaged as the test takes place.

Different facilities are utilized to provide different types and scales of hydrodynamic stress tests.  Some of these tests use large quantities of conventional explosive to simulate the kind of compression that occurs during a nuclear weapon’s detonation, while other tests are of a much smaller scale.

The facilities used for hydrodynamic testing exist at the Los Alamos National Laboratory, the Lawrence Livermore National Laboratory and the Nevada National Security Site.   The tests conducted are classified as subcritical nuclear weapons tests.

Materials Radiography Experiments – In order to assess the properties of nuclear materials and measure their reactivity with extreme precision, a wide variety of radiographic experiments are conducted.  Facilities to support this include the Los Alamos Neutron Science Center and Los Alamos Proton Radiography Facilities. One aim of continued research into radiography is to provide enhanced imaging capabilities for use in hydrodynamic and other types of shock tests.

The Z-Machine – The Z-machine is the world’s largest electrical discharge pulsed power generator. It is located at the Sandia National Laboratory, the Z-machine was first demonstrated to the public in 1998. It is basically an enormous bank of capacitors which can be discharged in a period of nanoseconds, producing power levels in the petawatt range.

The Z-machine has numerous uses, including generating super high power x-rays, testing how materials react to extreme electromagnetic shocks and producing small amounts of nuclear fusion by creating powerful magnetic pulsed fields around tiny capsules of easily fusible isotopes such as deuterium and tritium. It has also been used to produce small amounts of fusion in heavier elements.

Although the Z-machine has a myriad of uses in areas as widely varied as materials engineering, radiographic analysis and basic plasma physics, it was built primarily for the purpose of nuclear weapons research and this remains one of its main functions. The tiny amounts of fusion plasma produced by the Z-machine can be used to research the conditions that occur during a nuclear detonation as a way of validating computer simulations. The extremely energetic pulses produced by the machine are also used to test the properties of plutonium samples.

An interesting aside is that earlier this year, a congressional committed report on nuclear weapons research and stewardship stated:

The Committee understands that these experiments yielded fundamentally new and surprising data about the behavior of plutonium at high pressure and this new data has been one of the most valuable contributions to the stockpile stewardship program

Exactly what this “surprising” data is was not disclosed, but it goes to show that we still do not have a complete understanding of the unique properties of plutonium.

The National Ignition Facility – The National Ignition Facility represents one of the largest (and most expensive) scientific research programs currently underway by the United States Government. Construction began in 1997, but only recently has it begun to approach its full planned capacity. It is also possible that the facility will be upgraded further, as current systems have, thus far, been unable to produce full “ignition” of a nuclear fusion reaction – the point at which the reaction produces more energy than was used to initiate it.

NIF is the culmination of decades of research into inertial confinement fusion. In inertial confinement fusion, nuclear fusion is produced by subjecting a tiny target of material to a pulse of energy produced by high power lasers. With 192 of the world’s most powerful lasers, NIF dwarfs all facilities of this type that have come before it and is capable of achieving momentary temperatures as high as 3.3 million Kelvin. The energy directed at a small cylinder called a hohlraum. The laser energy vaporizes the cylinder and releases a burst of high intensity radiation which heats and implodes the fusion pellet.

If this sounds familiar, its because it’s the same way a hydrogen bomb works, except it is much smaller and the high intensity radiation which does the heating and imploding comes from the lasers striking the hohlraum and not from a fission primary explosive. Thus, the type of fusion reactions produced by the National Ignition Facility are really just tiny h-bombs.

When reported in the press, NIF is often described as a project to create clean, sustainable fusion-based energy. That, however, is not the reason NIF was built and it is not the primary type of research conducted at NIF. Although the facility may provide opportunities to better understand the physics of nuclear fusion in general, the actual purpose of NIF is to provide the ability to study the conditions that occur during nuclear explosions as a way of refining and validating computer models. Although it has received little attention, plans call for the us of weapons grade plutonium in NIF experiments, subjecting the plutonium directly to the kind of environment that occurs when a bomb detonates.

Why it matters:

  • Weapons tests not only assure that the weapon will work properly and reliably if fired, but also that it will not detonate inadvertently.  The compact two-point implosion systems used in some modern nuclear weapons can, if not designed properly, produce a significant nuclear yield, even if only part of the core is imploded.  The only way to fully assess the core characteristics under implosion and to determine if such hazards may exist is by full scale core testing.  Since partial implosions could produce significant fission yields, they are not currently conducted.
  • Questions about the reliability of US nuclear weapons could result in increased proliferation by causing other nations to feel the need to develop their own nuclear arsenals.  The United States is not the only country which is protected by the American nuclear umbrella.  Mutual defense and “nuclear sharing” agreements exist, assuring allies that they are protected against aggression by US nuclear arms.  After nuclear tests were conducted in North Korea, a number of officials in South Korea began to openly call for development of a South Korean nuclear program.  Similar calls to action have been made in Taiwan and Japan.   The United States countered this by reaffirming that American nuclear-equipped forces in the region were committed to responding to any aggression by North Korea, including a nuclear strike.  However, if doubts exist about the reliability of American weapons, countries like South Korea would have a very powerful motive to develop their own weapons.
  • Questions about the ability of nuclear weapons to continue to operate reliably into the future could result in pressure to use such weapons systems in the near term.  For example an argument could be made that “If we are going to use our nuclear bunker busters to destroy the Iranian nuclear program, we should do it now, when they will probably work.  If we want ten years, they might not be operational at all.”
  • Questionable reliability of weapons reduces their deterrent value and increases the likelihood of destabilization.
  • If the reliability of nuclear weapons is not well established, a larger arsenal will be required, as not all the weapons used will be expected to function properly.  For example, if up to 50% might fail, then twice as large an arsenal is required.
  • It is possible that an adversary, which has come to believe that the US arsenal is highly unreliable, could attempt to provoke a nuclear response from the US simply to determine if the weapons are, in fact, still fully functional.
  • If major reliability problems were discovered after they had become severe enough to impair a large portion of weapons from functioning properly,  much of the current stockpile would be forced to be withdrawn.  Since the US has retired many weapons and consolidated its forces into only a handful of designs, it is conceivable that discovering that the aging pits of one design had become extremely unreliable could result in much of the arsenal needing to be pulled from service.
  • In the future it may become desirable to modify existing weapons designs or to create new designs in order to improve safety and security.  For example, new methods of pit fabrication might reduce the likelihood of area contamination of a weapon were destroyed in a fire.  However, without testing, it would be difficult to incorporate such new designs into weapons systems while maintaining confidence that the weapon would function as expected.

It should be noted that these concerns are not exclusive to the United States.  Other countries with nuclear arsenals, which do not engage in testing, could also face such pressures, as the result of uncertainty about their stockpiles.   In fact, it could be much worse, as not all nuclear powers have access to the data from decades of testing which the United States does.

In terms of the ability to simulate full scale tests or acquire useful data by other means, most other nuclear powers do not possess the same level of computing power or the kinds of pulsed-power, hydrodynamic shock or high intensity pulsed fusion facilities the US has. Like the United States, France has been perusing Inertial Confinement Fusion as a means of gaining data related to nuclear weapons function, constructing the Laser Mégajoule, a facility similar to the National Ignition Facility.

Unfortunately, Russia, China, India and Pakistan do not have such facilities, which could bode poorly for their continued confidence in their nuclear stockpiles, possibly even to the point of some developing an “itchy trigger finger.”

Conclusion:

For those who have not already realized it, I personally favor the resumption of a limited number of periodic nuclear tests, conducted underground with rigorous measures taken to insure containment.   Such tests provide data that is very difficult to obtain otherwise and are the only way of absolute assurance of reliability in a way no other method can.  They also have the benefit of providing additional scientific data, offering an excellent opertunity for seismic sounding and providing data on nuclear reactions, geological forces and materials properties.

From the standpoint of peace and security, it should be noted that nuclear weapons exist and they are not going anywhere.   Nobody wants to see the day when such powerful weapons are fired in anger, but simply conducting tests does not increase the likelihood of this and may even reduce it.


This entry was posted on Friday, November 23rd, 2012 at 11:11 pm and is filed under Bad Science, Good Science, History, Misc, Nuclear, Politics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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17 Responses to “Do our nuclear weapons work?”

  1. 1
    drbuzz0 Says:

    It goes beyond the scope of this post, but I should mention there is one nuclear power which has not conducted any disclosed tests: Israel. Although Israel may have conducted a small scale test in the mid 1960′s and also may have tested a weapon in what became known as the “Vela Incident” they have not extensively tested their arsenal, which is estimated at 100-200 weapons.

    There is a lot of mystery around the Israeli nuclear weapons program and its the most secretive program out there. There is quite a bit of speculation about the possibility that their weapons may be direct copies of US or Russian nuclear weapons which they were able to obtain the designs for. They may also may have covertly participated in some French tests and it’s been alleged that France was paid large sums of money for weapons information.

    It’s known that there was some cooperation with South Africa and there is a high likelihood that some early weapons were a common design with South Africa. These would have been simple gun triggered devices, which are highly reliable and do not need as much testing. More advanced and miniaturized weapons came later.

    Israel has been very quiet on this and other countries have largely not been prying too hard (possibly concerned that revelations could destabilize the Middle East) Therefore, there is not much more than some educated speculation to go on.


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  2. 2
    Ryan Says:

    Half of the many nuclear tests were fizzles or failures. And I think I read some hwere that mass production reduced the quality of the nuclear cores.

    I think I remember reading something on the order of half of all missiles were expected to actually bring their payloads to target, as opposed to falling short, exploding in the silo, or missing.


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  3. 3
    Anon Says:

    Israel does seem to have a lot more bombs than they’d really need to effectively wipe out the Arab countries, that they’ve never tested any (the Vela incident was a malfunctioning satellite) would give them a good reason to make lots more than they’d otherwise need.

    On rocket reliability, I think we’re at the point at which most of the rockets fired would get near enough to their targets (though in the early days only half would probably have been seen as optimistic), though enemy ABM may complicate things (US and Russian missiles would probably do pretty well at getting past ABM).


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  4. 4
    JR Says:

    Not to get off topic, but I think there is pretty solid evidence that Israel managed to acquire their capabilities by piggybacking on the tests of others. France would be one, because in the 1950′s France was behind the UK and US with their program and it is known they had a big partnership with Israel to help speed up their own development. Israeli scientists worked with France in developing their H-bomb from the start. Israel may have cloned French weapons and been part of the testing. France also provided them with a reactor in 1956 and there is no doubt about that.

    It is an established fact that Israel developed indigenous uranium enrichment with South Africa and probably bought a lot of material from SA. The most early weapons used by Israel may have been the basis for South Africas weapons, but these were gun triggered and uranium based, reducing testing needs, as testing is more important with higher tolerance weapons.

    Some have claimed that the US provided testing opportunities to Israel. Officially the only country that the US has actively done joint weapons tests with is the UK. UK weapons were tested in Nevada after the Australia testing program ended. It has been insinuated that the US allowed Israel to use the cover of US nuclear tests to develop weapons and that this was part of military agreements or that it was motivated by a desire to avoid tests in Africa or Middle East which could have caused the whole area to boil over.

    Israel is just an enigma. Lots of hypothesis out there but official lips remain sealed.

    BACK ON TOPIC

    The fact that testing has ceased is because of the political movement which basically says that everyone wants a nuclear weapon free world and that therefore anything related to nuclear weapons, whether it is building more of them, refurbing the ones we have, testing them etc is bad and goes against the ideal that nuclear weapons (like some might say about guns, bombs and knives) are simply bad.

    This is fantasy. Nukes exist. You can’t uninvented them. There are countries which will absolutely not give them up. France will not, because the French will not allow their country to lose its place as an untippable world power. Israel won’t because Israel considers it a lot of firepower vital to their survival. China won’t because they fear the US as a military power, and because China won’t match the US in conventional weapon sophistication, they see nuclear weapons as an equalizer. Hence, the US or Russia would be a fool to get rid of the nuclear option. Perhaps downsize, but not disarm. That would be stupid.

    The pacifists ignore that modern nuclear deterrent doctrine works very well at stopping any aggression. Note that no nuclear missile has ever been fired in anger, despite high tensions.

    The doctrine that exists demands periodic testing. Testing does many things. For one, it does validate the reliability of weapons, which is more important than ever, with downsized inventories and modern design tolerances. It does something else too, which is not mentioned. Testing creates more openness, because it can be verified by everyone. An underground test produces a seismic event which can be used by the world to create a reliable estimate of the weapon yield and some other factors.

    Testing therefore avoids the condition where you have a country which might or might not have effective weapons and nobody really knows. This uncertainty can be dangerous.

    Yes, I would agree that there should be some testing resumed. The kind of tests conducted in the 1950′s and 1960′s, where extremely large yeilds were the norm and where hundreds of tests were conducted is not necessary and should not be encouraged. That was sabre rattling by the superpowers. the US and Russia would do well to conduct a small series of tests every couple of years. More importantly, countries like Pakistan, which have poorly tested and relatively unsophisticated arsenals need to do some more tests so that the safety and reliability of their capability can be established.


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  5. 5
    Ray Says:

    AN EXCELLENT POST I WILL CITE MANY TIMES I AM SURE!

    (I warn you, it is politically incorrect)

    One of the reasons for stopping testing was reported to be the expense. A full series of tests where they run a dozen tests of so will run into the billions of dollars.

    This seems to be less potent an answer, however, because post-testing we have found that trying to get the data we need costs at least as much. I don’t know how many billions has been spent on the ignition facility, but it was a lot and they spend billions on supercomputers and x-ray machines too.

    Safety has always been a concern, but its overblown. The big leaks of the 1960′s and 1970′s were caused by lack of experience in the complex problem of containing an undgeround test. That’s not how it needs to be because by the 1980′s, we had worked out things very well and tests were done in a way that is very safe and economical. We had expertise and knew where to drill and how deep to drill and what to explode for a safe test that gave good data.

    We are rapidly losing that expertise, sadly, because it’s now been 20 years and the best and brightest with the most experience now are hitting retirement. Give it another 20 years and there won’t be any left who actually had real world test experience.

    Did I mention that this is a very politically dangerous view to express? It seems the prevailing wisdom is anyone who worked in the field just wanted to wipe out human kind.


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  6. 6
    RBR1982 Says:

    I myself would like to see the treaties on testing amended to allow for nuclear explosions to be studied and used as a way of propelling spacecraft and doing things like asteroid mining or building underground cities on mars. I think that they are probably the only thing we have with enough raw power to make it possible to push space exploration way past the limits it has now.


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  7. 7
    DV82XL Says:

    The fact is is that it was well understood at the time these treaties were signed that the halting of testing would limit the confidence of any nuclear State in the reliability of its arsenal, in fact that was one of the objectives of a comprehensive test ban. Many at the time were worried about the possibly of a preemptive strike by one of the protagonists in the Cold War. In fact there were many that favored a swift “decapitation” strike against the nuclear assets of the enemy in the event that hostilities broke out in Europe. While no one ever stated this as official nuclear doctrine, the feeling on all sides was that such a doctrine did exist or that military planers could convince political decision-makes to go this route too easily in a crises.

    Thus the whole idea behind stopping testing was to introduce an element of doubt that would deter any temptation for First Use. It was, of course, assumed at the time that by now nuclear weapons would be eliminated so the other issues that are now emerging with the stockpile would not have had time to develop.

            RBR1982 said:

    I myself would like to see the treaties on testing amended to allow for nuclear explosions to be studied and used as a way of propelling spacecraft and doing things like asteroid mining or building underground cities on mars.

    I think that they are probably the only thing we have with enough raw power to make it possible to push space exploration way past the limits it has now.

    There was a Peaceful Nuclear Explosions Treaty in 1976 that permitted nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals. During the 1960′s and 1970′s, both the United States and the Soviet Union conducted a number of PNEs. These did not demonstrate much utility and were subsequently disallowed under the terms of the Comprehensive Nuclear-Test-Ban Treaty of 1996.


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  8. 8
    Nick P. Says:

    I tend to look at this practically:

    If we’re going to spend countless millions and billions of dollars keeping the things around it would at least be nice to know that they’ll go *BOOM* when they’re supposed to. Otherwise we’ve accomplished what exactly?


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  9. 9
    Ray Says:

    DV82XL: I have heard those kind of arguments many times before, but they are flawed for a number of reasons.

    First, nuclear weapons are not going anywhere. You cannot uninvent them and how to build them is now widely known. It would be foolish to give them up unless every country did, and as I said for the reasons above, that will not happen. The other problem is that if you had the current countries give up their arsenals, then it would create a very dangerous situation, where any country could have either horded a few away or start to build new ones and then have a monopoly, which would be a big problem.

    It is less dangerous to have a few countries armed with nuclear weapons than it is to run the danger that a single country would become armed with nuclear weapons and have no counterbalance.

    The idea that we were on the verge of banning them was a myth that came up in the 1980s with the signing of some arms limitation treaties. Limits are fine because they save money and prevent a race to out gun the other, but an all out ban of the whole stockpile is not good for anyone.

    Also, lack of confidence in the weapon could cause the opposite effect of what you suggest.

    Suppose in a post testing era, a conflict breaks out between Russia and the United States. If Russia were confident in their nuclear weapons, they would feel the chances of the US attacking were very low because the US would surely face overwhelming retaliation for a first strike.

    However, what if not testing the weapons caused the Russians to lose confidence that they will all work? They know if the US suddenly attacks them, their aircraft delivered bombs are going to be destroyed and their large silo-based ICBMs will likely be destroyed before they can respond as well. They therefore prevent the attack because they have what is called a ‘second strike’ capability from highly survivable weapons like submarine launched ballistic missiles and road mobile icbms.

    The Russian Government could become concerned, because these kind of weapons have the smallest sized warheads in terms of mass and size. They have to fit into a very small reentry vehicle and that means they must have extremely high tolerances. This makes them the most prone to problems. (NOTE that the W76, the US weapon which has been subject to possible problems is an SLBM warhead. It uses special, possibly problematic materials to fit in a small package and it only weighs 400 kg)

    If Russia becomes concerned that their second strike weapons will not work, they may still be reasonably confident that their bigger, lower tolerance weapons will work and those weapons are higher yield anyway, which means even if they don’t achieve full design yield, they are still effective.

    They could become paranoid that the US is aware of the problem and decide that the only way to avoid attack is a first strike with their large ICMBs and manned bombers, because their second strike is not viable.

    Second alternative: If Russia believes that the second strike capability of the US is compromised by unreliable SSMBs, they may think this gives them a shot to destroy the land based weapons and avoid any response.


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    DV82XL Says:

    Ray – I was not implying these reasons were good ones, but they were the ones being used at the time, which is why you have seen them come up before. Keep in mind that the first, The Limited Test Ban Treaty was signed and ratified in 1963 and had been in negotiation from the mid Fifties, and that the original intention was a full testing ban along with a disarmament agreement. It fell short of that of course but there was a real concern on all sides at the time.

    Your contention that lack of confidence in the weapon could cause the opposite effect of what I stated, simply is not valid. All First Strike doctrines target the opponents own nuclear weapon assets first with the intention of eliminating or severely reducing the capability to counter-strike. Not knowing the effectiveness of such an attack does serve as a deterrent to mounting one. Keep in mind this is not a question of yield, but one of the weapon functioning at all. Yes indeed there was much effort made to keep a second strike (really a counter-strike) capability, but but by it very nature, one would not commit such assets to an initial strike. Furthermore the number of these were relatively small, since their function was largely punitive rather than anything else.

    This is not some fantasy of mine, but is standard thinking in the field. I suggest you look at some of the declassified material available that shows some of the thinking coming out of RAND at the time.

    I have no doubt that there were military voices on both sides that were convinced that a first strike was the best option, however as then US President L.B. Johnson said publicly on September 1964; “Make no mistake, there is no such thing as a conventional nuclear weapon. For 19 peril-filled years no nation has loosed the atom against another. To do so now is a political decision of the highest order.” It would appear that even then it was realized that the rules of international conflict had changed, and that the world’s political leadership were sharply aware of it. No one in power would have entertained the idea of a first strike and this is for the simple reason that unlike any other form of warfare, nuclear weapons put political leaders right in the trenches with everyone else’s son, and that has been a tremendous way to keep them focused on the implications of these decisions.


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    Ray Says:

    DV82XL, Missing most of what I said here.

    The whole point of a second strike capability is to prevent a preemptive strike by having enough weapons to survive that. The submarine ballistic missile is the ultimate insurance policy. A first strike could destrit manned bombers and land-based ICBMS but subs survive. Nobody would be foolish enough to try a first strike as long as the boomers are ready to fire back.

    Our submarines are armed with the notorious W76, mentioned above. What happens if an enemy decies that the W76 is so unreliable that most probably won’t function at all? Now they have the chance to take out all viable weapons and not worry about a second strike.


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    Anon Says:

            Ray said:

    What happens if an enemy decies that the W76 is so unreliable that most probably won’t function at all? Now they have the chance to take out all viable weapons and not worry about a second strike.

    More like the US would just launch the ICBMs and bombers really quickly before the first strike hits.


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  13. 13
    Radiation Bulletin: Fuel Cycle/DOE: Nov. 19th – 25th 2012 | The Energy Net Says:

    [...] Depleted Cranium – Do our nuclear weapons work? [...]


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    Radiation Bulletin: Nuclear News: Nov. 19th – 25th 2012 | The Energy Net Says:

    [...] Depleted Cranium – Do our nuclear weapons work? [...]


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    DV82XL Says:

    Ray – No I understand the point you are trying to make, however it is fundamentally wrong. No one would make the assumption that the other’s weapons were so unreliable that most probably won’t function, this was never part of the reasoning. No testing only means nether side has the confidence to believe that they can take out the other side’s assets reliably enough to avoid retaliation. Keep in mind that things developed over a number of years and both sides adjusted their doctrines to reflect the changing geopolitical landscape as various treaties came into force. Second Strike doctrines were a later development and have themselves been refined into the so-called “countervailing strategy” of Jimmy Carter/ Harold Brown.

    Nevertheless it really doesn’t matter what you think in this regard – test bans were negotiated and treaties signed for the reason I stated and indeed, if you read the now declassified documents from that era, all parties were well aware of what they were doing and why.

    Now it is true that this has led to an unacceptable technical situation where unreliability has developed to the point where the existing stockpile has become unsafe and it is also true that the geopolitical situation has changed such that the specter of a full nuclear exchange between superpowers has vanished, so I believe that testing should be resumed because the more likely need will be for small strikes and these require very reliable weapons to be effective, or at least an effective threat.


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    Q Says:

    What about the idea that if everyone stops testing it would help preserve the status quo for the existing powers?

    The United States, Russia, France etc, have all tested in the past and they now have weapons they can count on because of that, but without testing at all, no new powers can enter “the club” and those who have relatively crude weapon designs end up being stuck with them and will not be able to advance further to build better ones.


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    DV82XL Says:

            Q said:

    What about the idea that if everyone stops testing it would help preserve the status quo for the existing powers?

    The United States, Russia, France etc, have all tested in the past and they now have weapons they can count on because of that, but without testing at all, no new powers can enter “the club” and those who have relatively crude weapon designs end up being stuck with them and will not be able to advance further to build better ones.

    First, they cannot count on them, that is the crux of the matter. Testing not only verifies design, but also is needed to calibrate existing warheads as things change over time inside them because many of the components are inherently unstable or at least age in unpredictable ways.

    It is not the Comprehensive Test Ban Treaty that is supposed to keep new members out of the nuclear weapons club, but rather the Non- Proliferation Treaty which outright forbids any signatory not grandfathered in from developing weapons.


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