Editor’s note: This post was first published on Jul 24, 2010. While working on a new post involving the use of fast spectrum reactors to address many important society challenges, I thought it would be worthwhile to share this important background piece to let you start thinking about some of the misinformation you might have been taught over the years.

I have been struggling for the past couple of weeks with trying to figure out how to convince some curious and skeptical people that they should stop worrying about the possibility that a nefarious group or country will make a weapon from used nuclear reactor fuel. My position is that there is no way for an ad hoc group of terrorists or nefarious state actors to build a weapon out of used commercial nuclear fuel.

The challenge is that I have a self-appointed task of proving a negative when the positive assertion has been well publicized and firmly established as a “fact” by people with impressive credentials. I also have to figure out how to make this argument without access to technical details that remain classified. Finally, I have to do it in a way that does not require readers to work their way through the excellent, but lengthy explanation provided by Why You Can’t Build a Bomb From Spent Fuel or Alexander de Volpi’s excellent and accessible document titled A CENTURY OF PROGRESS in Nuclear Information and Understanding.

People who have successfully worked to establish a legal precedent declaring that used commercial nuclear fuel can be used as bomb material point to a test explosion conducted at the Nevada Test Site as a key piece of evidence. In 1977, President Carter, in order to provide some technical basis for his executive decision to halt all US nuclear fuel recycling efforts, declassified the fact that an experimental explosive device using “reactor-grade” plutonium had been tested in 1962. He did not allow any additional details to be released, claiming national security concerns.

On June 27, 1994, Hazel O’Leary, who was serving as the Secretary of Energy in the Clinton Administration, ordered publication of a DOE Fact Sheet as part of the Openness Initiative. That document informed the public that the 1962 test used plutonium provided by the United Kingdom under the 1958 United States/United Kingdom Mutual Defense Agreement. The Fact Sheet stated that test produced a yield less than 20 kilotons, but the exact yield was not released. The Fact Sheet did not provide the isotopic composition of the material because the people who reviewed the information about the test determined that releasing composition information could be useful to “proliferants”.

However, it is possible to make some assertions about the material.

The material used in the test was produced in a UK reactor and made available for testing before the end of 1962.

Due to the time required to cool the material, process it, transport it to the US, assemble into a device, and set up an experiment at the Nevada Test Site, it must have been removed from the source reactor by no later than the end of the summer of 1962.

The only commercial reactors operating in the UK by mid 1962 were Magnox (Magnesium Oxide) reactors that used natural uranium and graphite moderation with CO2 cooling.

However, the first Magnox reactors at Calder Hall and Chapelcross were openly admitted weapons material production reactors that sold electricity as a side product. Any material from those reactors would be seen as “weapons grade”, vice “reactor grade”, so a test using material from Calder Hall or Chapelcross could be dismissed as proving nothing about the explosive potential of reactor grade plutonium.

Berkeley Station, which began operation in mid 1962, was the first Magnox reactor that was not operated with a dual purpose. The Central Electricity Generating Board owned the Berkeley Station, not the UK Atomic Energy Authority.

Therefore, the plutonium used in the test came from a natural uranium, graphite moderated reactor irradiated for a brief period of time. The resulting plutonium isotopic composition must have been quite similar to the composition normally defined to be weapons-grade material.

The most likely candidate as the actual test that used the UK provided plutonium as raw material was called Tendrac, which was part of the Operation Storax series of nuclear explosive experiments. (Note: According to a joint DOE/NV document titled United States Nuclear Tests July 1945 through September 1992, Tendrac was a Joint US-UK test which took place on December 7, 1962 with a listed yield of “Low”. It was the only Joint US-UK test conducted during the second half of 1962.)

There is no way that the 1962 experimental explosive device could have contained the isotopic mix that would be representative of plutonium irradiated in a modern commercial reactor. The available irradiation time was far too short and the reactor used to produce the uranium was not capable of the higher burn-ups produced in operating light water cooled commercial nuclear power plants. Anyone who points to the 1962 test as “proof” that reactor grade material is a proliferation hazard is either uninformed, technically incompetent, misinformed or lying. There is no other choice.

A frequent discussion topic in the early to mid 1970s was the possibility of moving from a hydrocarbon economy to a plutonium economy. The people who advocated for a plutonium economy described how breeder reactors can eliminate human concerns about having sufficient stores of reliable energy. (Note: The most commonly discussed type of breeder reactor turns U238, the isotope that represents 99.3% of natural uranium, into plutonium isotopes useful as power reactor fuel. Of course, there are also breeders that convert thorium 232 into uranium isotopes for fuel, but those were not as well known during the plutonium economy discussions.)

If you understand how much money is tied up in the establishment hydrocarbon economy you might understand why talk of a plutonium economy caused large scale resistance to efforts to deploy the required enabling technology. Hydrocarbon promoters were joined in their fight against plutonium by people who revel in a “Limits to Growth” philosophy. Breeder reactors and plutonium reuse opens up the possibility of endless energy supplies that make it possible to overcome almost any material supply limitation.

One plank in the anti-plutonium platform was the fear-inducing assertion that an ad hoc group of “terrorists” could use stolen reactor grade plutonium as the raw material for a nuclear weapon. A key part of the evidence used to support this assertion was the “known fact” that the US had conducted a test using “reactor grade” plutonium that they claimed conclusively proved that any of the known difficulties associated with reactor grade plutonium could be overcome.

Most of the technical experts who might have disputed this politically driven assertion still worked within the cloistered nuclear weapons production enterprise, but even if they had not been professionally restricted from comment, most of the technical detail required to dispute the assertion would have been too complex or too highly classified for a public debate.

For the 33 years since 1977 there has been little to no resistance within the US to the established policy of considering reactor grade plutonium as “weapons usable”. This policy has helped to restrict nuclear energy developments by adding cost and by helping to inflate concerns about nuclear waste. When nuclear energy skeptics ask “what do you do with the waste”, nuclear advocates have been unable to easily answer “we’ll recycle it” since that answer violates US policy and would not be easy to implement.

Knowing what you now know about the actual material used in that test, you have the information required to question the assertion that reactor grade material is useful for weapons. You should also use your critical thinking skills to question the motivations of the people who pushed so hard for so many years to force other nations to forgo actions to recover valuable raw material from used nuclear fuel.

Fuel assemblies removed from commercial nuclear reactors still contain 95% of the initial potential energy. The material is not even close to pure enough for the very specialized purpose of turning it into a weapon, but even with its complicating impurities, it is acceptable for use as fuel for new power producing reactors.

The US should stop worrying about the vanishingly remote possibility that commercial nuclear fuel recycling facilities could be cover operations for states with nuclear weapons ambitions or that they might be useful targets for nefarious folks. We should use our new understanding to help restore the expansive vision for future prosperity that President Eisenhower shared when he said the following:

The United States knows that peaceful power from atomic energy is no dream of the future. The capability, already proved, is here today. Who can doubt that, if the entire body of the world’s scientists and engineers had adequate amounts of fissionable material with which to test and develop their ideas, this capability would rapidly be transformed into universal, efficient and economic usage? (Emphasis added.) Source – December 9, 1953 – Atoms for Peace speech to the United Nations.

Additional Reading

George Mitchell, father of hydraulic fracturing and a fan of Limits to Growth. George Phydias Mitchell’s Story

Note: Please see reference to the influence of Limits to Growth on the nuclear non-proliferation movement.