Probabilistic Proliferation Risk Assessment and the LFTR

At times I find myself out in front of my contemporaries. I learned about Anthropogenic Global Warming (AGW) while I had what amounted to an internship at ORNL in 1971. ORNL had not taken AGW seriously before 1971, and for a number of years after, it was the only place on the earth were AGW was taken seriously. After I left ORNL I never doubted that AGW was in the offing even if the scientific evidence was not in. I am amazed that 38 years later there are still intelligent educated people, who doubt what seemed obvious to me in 1971. Although I am not a scientist, I was able to spot an important development in science sometime before it became a matter of general concern in the scientific community.

I believe that my adoption of the probabilistic risk assessment approach to nuclear proliferation is another case where I adopted an advanced mode of thinking. About two years ago I began to review concerns about nuclear proliferation. Now let me first state that I am very concerned about nuclear proliferation. I regard it as a very bad thing that the government of an unstable country like Pakistan has control of nuclear weapons. I regard it as a very bad thing that the government of Iran, a nation whose political leadership is exercised by a group of theocratic religious fanatics, whose morality and understanding of their world is stuck somewhere in the middle ages, is working to develop nuclear weapons. I find it reprehensible that a Pakistani scientist, A.Q. Kahn, was able to steal the design to advanced Uranium Enrichment technology, and to pass that technology on to unstable and rogue states including Pakistan, Iran, Libya, and North Korea. I find it shocking that the design of a reactor intended to produce plutonium for military purposes was placed into the public domain during the 1960's and that any rogue state which wishes to obtain that technology can do so, provided enough cash finds its way to certain North Korean leaders.

It is quite obvious to me that proliferation control is no longer about controlling technology. Proliferation is a political issue. Proliferation must be controlled through diplomacy and international pressure on would be proliferating states. The technology to create bomb grade fissionable material is available to virtually any rogue state that wants to build nuclear weapons. Only a concerted international political effort can stop the spread of nuclear weapons in the present environment.

Shortly after I started debating anti-nuclear types a couple of years ago, I noted an absurdity in their argument, and a contradiction between two other arguments. The absurdity was the notion that building reactors in the United States would cause rogue states to acquire nuclear weapons. The absurd argument when like this: Reactors produce plutonium, plutonium is used nuclear weapons. If we build plutonium producing reactors in the United States, it is inevitable that they will spread to other countries, and equally inevitable that plutonium will fall into the hands of rogue states and terrorists. Inevitably then bad people will acquire nuclear weapons. Conclusion, the way to prevent nuclear proliferation is to not build reactors in the United States.

Faulty premises, faulty conclusions. A de facto moratorium on reactor construction in the United States did not in fact stop the manufacture in other countries. France decided to produce most of its electricity with reactors. This is now a fact. Japan and South Korea built lots of reactors and much of their electrical production is via reactors. India continued on a long term plan to develop local nuclear technology, that would eventually place India in the forefront of nuclear power production. Thus even without the construction of new nuclear reactors in the United States, Nuclear power technology continued to develop and spread to other countries.

There was another flaw in the premise of this argument. There are several different isotopes of Plutonium. In terms of bomb making, not all of the isotopes of plutonium are made equal. Pu-239 is the stuff you build bombs from. Pu-241 also works well. But Pu-238, Pu-240 and Pu-242 are worse than useless to bomb makers. In particular Pu-240 is very bad news for bomb makers, and it is considered very desirable to keep the Pu-240 content of plutonium used in nuclear weapons below 7% of the plutonium content. While Pu-240 is not itself explosive, it can cause the explosive forms of plutonium, Pu-239 and Pu-241 to explode prematurely. Such premature explosions will have an explosive force similar to that of conventional chemical explosives. At least 25% of the plutonium in spent reactor fuel is Pu-240. Now here is the paradox. It is a well know fact that ammonia fertilizer can be turned into a low cost but effective high explosive. The biggest explosion would be proliferators are going to get from the spent reactor fuel plutonium would be the equivalent of the explosion that could be produced by $150,000 worth of fertilizer.

It would take millions of dollars to recover the plutonium that went into the weapon from reactor fuel. Lets play a you are a terrorist game. You are a terrorist. You are considering setting off a very large explosion in a famous western city. You have two options. The first option is to obtain a large amount of spent nuclear fuel, handle the spent fuel without exposing your people to a lethal amount of radiation. Spend hundreds of millions of dollars extracting the plutonium from the spent fuel, engage your scientists and engineers in the technologically challenging task of building a weapon from the recovered plutonium (hint: having the weapons building resources of Los Alamos would help). Secretly transport the resultant device to the Western city and set it off.

The second option is to secretly assemble $150,000 worth of ammonia fertilizer in a Western city. Rig it to explode. Set it off.

The two plans will produce explosions equal to the effect of 400 tons of TNT. Which plan would you chose? Would you be more likely to set off the explosion because you could chose to use the plutonium device? A rational actor would notice that the second plan was far simpler, and far less expensive, and despite risks, far more likely to succeed. Thus a rational terrorist would choose plan B. If we were to asses the risk of terrorists setting off a large explosion in a western city, given the existence of the two options, we would have to say that the existence of the nuclear option does not increase the likelihood of a large terrorist explosion, even if the terrorist chose to build the nuclear weapon, for had the terrorist not chosen to do so, the terrorist would have likely chosen the conventional explosives route. In fact the terrorist choice of the nuclear route would have decreased the likelihood of the explosion taking place, given the expense and difficulty of developing a nuclear device. Thus the supposed nuclear choice was very unlikely to effect the terrorists behavior, and to the extent it did, it would have somewhat decreased the likelihood that a major terrorist act would take place. The explosive effects of the conventional explosive and the nuclear device would have been the same.

Now let us consider the contradiction. Critics of nuclear power often argue that extraction of Plutonium from spent nuclear fuel is so technologically challenging and expensive as to be a wholly impractical option. At the same time the extraction of plutonium from spent nuclear fuel for the purposes of weapons manufacture is depicted, often in the same essay as trivially easy. Now both cannot be true at the same time. As we have seen whether or not the extraction of plutonium from spent nuclear fuel is a practical option, the building of nuclear weapons from that plutonium is not a practical option.

We must now consider a Statement by Clinton Era Arms Control and Disarmament Agency Director John Holum explained the situation clearly in a memorandum to former Energy Secretary Hazel O'Leary:

"U.S. decisions on plutonium disposition are inextricably linked with U.S. efforts to reduce stockpiles as well as limit the use of plutonium worldwide. The multi-decade institutionalization of plutonium use in US commercial reactors would set a very damaging precedent for US non-proliferation policy."

The above statement suggests that Clinton era United States Non-proliferation policy was wrong-headed. The use of plutonium in United States Reactors does not promote nuclear proliferation.

I would now like to turn to the alleged proliferation potential of Liquid Fluoride Thorium Reactors. In particular I would like to direct these remarks to commenters on the Energy from Thorium Form (EfT) who do not take into account the probabilistic method of assessing proliferation risks. I have argued that from a rational perspective the LFTR is unlikely to pose a proliferation risk. In contrast a number of EfT commenters continue to express concerns about the proliferation dangers posed by allegedly risky LFTR technology. While these commenters are individuals whose views I generally regard with a great deal of respect, I have noted that their views seem to ignore the argument that LFTR technology is very unlikely to play a role in future nuclear proliferation, and that well known paths to the development of nuclear weapons will continue to be followed by future would be nuclear proliferators. Thus adding supposed anti-proliferation features to the LFTR would not decrease the extremely small risk that LFTRs would be used as a means to develop nuclear weapons. Further, it is a matter of legitimate concern that such features are not only pointless but could increase LFTR expenses, and potentially cripple the LFTR.

No anti-proliferation concern is served by adding proliferation features to LFTRs sold in the United States. The U-233 produced by American LFTRs would be very unlikely to cause rogue states or terrorists to build nuclear weapons. Protection of LFTR produced U-233 from diversion is primarily a security rather than a technical issue. It is my viewpoint that public debate regarding security measures used to protect nuclear material and technology is likely to help terrorists who might wish to seek to defeat nuclear security, by offering them tips about what to expect. Thus I am going to specify that it is an obligation of the Nuclear Regulatory Commission to see to it that high levels of security are provided for U-233 and other potential bomb construction materials, and leave the how to others.

Secondly most potential LFTR customers outside the United States either possess nuclear weapons, or the capacity to build nuclear weapons if they so chose. Possession of the LFTR is not likely to increase the weapons stocks of existing nuclear powers. Nor would possession of the LFTR increase the likelihood that nations that already possess the capacity to develop nuclear weapons would choose to do so.

This would leave a group of states that are less technologically advanced, but might now in the future seek to posses nuclear weapons. The danger of proliferation via LFTR technology might be a legitimate concern with these states even if a probabilistic risk assessment might reveal that the danger was unlikely. In such cases, there could be an option to sell the at risk state other low risk nuclear technology.

It would appear then that efforts to make the LFTR more proliferation resistant are not needed. The existence of real LFTR technology is unlikely to to lead non-nuclear weapons states to acquire nuclear weapons, and measures required to make the LFTR more proliferation are unlikely to greatly diminish the probability of nuclear proliferation while increasing LFTR cost and having other adverse consequences. I urge my peers to adopt a probabilistic approach to the assessment of LFTR proliferation risks.