PLUTONIUM AND BOMBS

 

PLUTONIUM AND BOMBS

The very existence of plutonium is often viewed as the work of the devil.^* As the most important ingredient in nuclear bombs, it may someday be responsible for killing untold millions of people, although there are substitutes for it in that role if it did not exist. If it gets into the human body, it is highly toxic. On the other hand, its existence is the only guarantee we have that this world can obtain all the energy it will ever need forever at a reasonable price. In fact, I am personally convinced that citizens of the distant future will look upon it as one of God's greatest gifts to humanity. Between these extremes of good and evil is the fact that if our nuclear power program continues to be run as it is today, the existence of plutonium will have no relevance to it except as a factor in technical calculations.

Clearly, there are several different stories to tell about plutonium. We will start with the future benefits, then discuss the weapons connection, and conclude with the toxicity question.

Fuel of the Future

As uranium occurs in nature, there are two types, U-235 and U-238, and only the former, which is less than 1% of the mixture, can be burned (i.e., undergo fission) to produce energy. Thus, present-day power reactors burn less than 1% of the uranium that is mined to produce their fuel. This sounds wasteful but it makes sense economically, because the cost of the raw uranium at its current price represents only 5% of the cost of nuclear electricity (see Chapter 13 Appendix). However, there is only a limited amount of ore from which uranium can be produced at anywhere near the current price, perhaps enough to provide lifetime supplies of the fuel needed by all nuclear power plants built up to the year 2025. Beyond that, uranium prices would escalate rapidly, doubling the cost of nuclear electricity within several decades.

Fortunately, there is a solution to this problem. The fuel for present-day American power plants is a mixture of U-238 and U-235. As the reactor operates, some of the U-238, which cannot burn, is converted into plutonium. This plutonium can undergo fission and thus serve as a nuclear fuel. In fact, some of it is burned while the fuel is in the reactor, enough to account for one-third of the reactor's total energy production. But some of it remains in the spent fuel from which it can be extracted by chemical reprocessing. This plutonium could be burned in our present power reactors, but an alternative is to use it in another type of reactor, the breeder, whose fuel is a mixture of plutonium and uranium (U-238). Much more of the U-238 in the breeder is converted to plutonium than in our present reactors, more than enough to replace all of the plutonium that is burned. Thus, a breeder reactor not only generates electricity, but it produces its own plutonium fuel with extra to spare. It only consumes U-238, which is the 99+% of natural uranium that cannot be burned directly; therefore, it provides a method for indirectly burning this U-238. With it, nearly all of the uranium, not less than one percent as in present type reactors, is eventually burned to produce energy. About a hundred times as much energy is thus derived from the same initial quantity. That means that instead of lasting only for about 50 years, our uranium supply will last for thousands of year. As a bonus, the environmental and health problems from uranium mining and mill tailings will be reduces a hundred fold. In fact, all uranium mining could be stopped for about 200 years while we use up the supply of U-238 that has already been mined and is now in storage.

Deriving 100 times as much energy from the same amount of uranium fuel means that the raw fuel cost per kilowatt-hour of electricity produced is reduced correspondingly. In fact, the fuel costs per unit of useful energy generated in a breeder reactor are equivalent to those of buying gasoline at a price of 40 gallons for a penny! (see Chapter 13 Appendix). Instead of contributing 5% to the price of electricity as in present-type reactors, the uranium cost then contributes only 0.05% in a breeder reactor. If supplies should run short, we can therefore afford to use uranium that is 20 times more expensive, for even that would raise the cost of electricity by only (20 x .05 =) 1%. How much uranium is available at that price?

The answer is effectively infinite because it includes uranium separated out of seawater.¹ The world's oceans contain 5 billion tons of uranium, enough to supply all the world's electricity through breeder reactors for several million years. But in addition, rivers are constantly dissolving uranium out of rock and carrying it into the oceans, renewing the oceans' supply at a rate sufficient to provide 25 times the world's present total electricity usage.² In fact, breeder reactors operating on uranium extracted from the oceans could produce all the energy humankind will ever need^* without the cost of electricity increasing by even 1% due to raw fuel costs.

The fact that raw fuel costs are so low does not mean that electricity from breeder reactors is very cheap. The technology is rather sophisticated and complex, involving extensive handling of a molten metal (liquid sodium) that reacts violently if it comes in contact with water or air. Largely as a result of the safety precautions required by this problem, the cost of electricity from the breeder will be substantially higher at today's uranium prices than that from reactors now in use.³ Nevertheless, France, England, and the Soviet Union have continued with developing breeder reactors, and several other countries, including Germany and Japan, are involved to a lesser degree. The American program was at the forefront 20 years ago, but it became a political football and is now essentially dead.

On the surface, the opposition to the U.S. breeder reactor is based on the fact that uranium supplies are plentiful and cheap, leaving little incentive for an expensive development program at this time (less expensive research is continuing, most notably in a test reactor at the Hanford site in Washington State). Why, then, have other countries continued to press on with their development programs? First, even if development goes forward at the hoped-for pace, it will be many years before the first commercial breeder can become operational and many more before its use would become widespread; it is better to start up any new technology slowly, allowing the "bugs" to be worked out before a large number of plants is built. Second, we are not that certain about our uranium resources; they may be substantially below current estimates. Having the breeder reactor ready would be a cheap insurance policy against that eventuality, or against any sharp increase in uranium prices for whatever the reason. And third, the breeder reactor development program has substantial momentum, with lots of scientists, engineers, and technicians deeply involved. It is much more efficient to carry the program to completion now than to stop it, allow these people to become scattered, and then start over with a new team of personnel later.

Not far beneath the surface, there is substantial opposition to the breeder because of distaste for plutonium and general opposition to nuclear power. There are also some fears about the safety of breeder reactors, but experts on that subject (of which I am not one) maintain that they are extremely safe, and even safer than present reactors.^3,8 They have the important safety advantage of operating at normal pressure rather than at very high pressure, as is the case for present reactors. There are therefore no forces tending to enlarge cracks or to blow the coolant out of the reactor (this is the blowdown discussed in Chapter 6.).

A key part of the breeder reactor cycle is the reprocessing of spent fuel to retrieve the plutonium. In fact, this must be done with the spent fuel from present reactors in order to obtain the plutonium necessary to fuel the first generation of breeder reactors. As long as there is no reprocessing, the plutonium occurs only in spent fuel, where it is so highly dilute (of 1% of the total) that it is unusable for any of the purposes usually discussed. Moreover, spent fuel is so highly radioactive (independently of its plutonium content) that it can only be handled by large and expensive remotely controlled equipment. It therefore cannot be readily stolen or used under clandestine conditions. Without reprocessing, there is no use for plutonium for good or evil.

It should also be recognized that plutonium plays only a minor role in waste disposal problems, and a negligible role in reactor accident scenarios. Thus, as long as there is no reprocessing, which is the present status in the United States commercial nuclear power program, plutonium issues have no direct relevance to the acceptability of nuclear power.

However, it is my personal viewpoint that it is immoral to use nuclear power without reprocessing spent fuel. If we were simply to irretrievably bury it, we would consume all the rich uranium ores within about 50 years. This would deny future citizens the opportunity of setting up the breeder cycle, the only reasonably low-cost source of energy for the future of which we can be certain. By such action, our generation might well go down in history as the one that denied humankind the benefits of cheap energy for millions of years, a fitting reason to be eternally cursed. On the other hand, if we develop the breeder reactor, we may go down in history as the generation that solved the world's energy problems for all time. Future generations might well remember and bless us for millions of years.

Unfortunately, the people in control are not worried about the long-range future of mankind. People in the nuclear power industry are concerned principally about the next 30 or 40 years, and politicians rarely extend their considerations even that far into the future. Whether or not we do reprocessing will have little impact over these time periods; thus the prospects for early reprocessing are questionable.

The situation was very different only a few short years ago. A large reprocessing plant capable of servicing most of the power plants now operating in the United States was constructed near Barnwell, South Carolina, by a consortium of chemical companies. The main part of the plant, costing $250 million, was completed in 1976, but two add-ons that would have cost about $130 million were delayed by government indecision. Since the add-ons would not be needed for several years, it was expected that the main part of the plant could be put into immediate operation.

At that critical point, the U.S. Government decreed an indefinite deferral of commercial reprocessing. The reason for the decree involved our national policy on discouraging proliferation of nuclear weapons, which will be discussed later in this chapter, but from the viewpoint of the plant owners, it was a disaster. They had been strongly encouraged to build the plant by government agencies — for example, federally owned land was made available to them for purchase — and every stage of the planning was done in close consultation with those agencies. They had scrupulously fulfilled their end of the bargain, laying out a large sum of money, and now they were left with a plant earning no income.

By the time the Reagan Administration withdrew the decree forbidding reprocessing 5 years later, the owners had lost heart in the project and were unwilling to provide the money, now increased to over $200 million, to provide the add-ons. The Barnwell plant was abandoned. It is generally recognized that there will be no commercial reprocessing in the United States unless the government provides assurances that money invested would be compensated if the project were again terminated by political decree, and guarantees to purchase the plutonium it produces. The latter requirement is necessary because the Barnwell plant was originally built with the understanding that utilities could purchase the plutonium to fuel present reactors, but the government has not taken action to allow this and probably will never do so. It is now widely agreed that it would be better to save the plutonium for breeder reactors. Since there are no commercial breeder reactors in the United States and will not be any for many years, this leaves the government as the only customer for the plutonium from a reprocessing plant.

Aside from the idealistic considerations of providing energy for future generations, an additional driving force behind getting reprocessing plants into operation is their contribution to waste management. Power plants are having difficulty in storing all of the spent fuel they are discharging; reprocessing gives them an outlet for it. Furthermore, the amount of material to be buried is very much reduced if the uranium is removed in reprocessing. There is also considerably more security in burying high-level waste converted to glass and sealed inside a corrosion-resistant casing, than in burying unreprocessed spent fuel encased in asphalt or some similar material.

On the other hand, there has been strong opposition to reprocessing. There have been well publicized attacks on its environmental acceptability, ignoring the contrary evidence in the scientific literature in favor of "analyses" by "environmental groups" tailored to reach the desired conclusion. There were widely publicized economic analyses of unspecified origin claiming that reprocessing was a money-losing proposition, even when the real professionals in the business considered it to be economically advantageous.⁹ There was a considerable amount of publicity for a paper issued by the DOE claiming that the Barnwell plant was technically flawed,¹⁰ but it turned out the paper was by a scientist with little experience in the field who had never visited the plant and was confused over differences between reprocessing fuel from present power reactors and breeder reactors; the paper had accidentally slipped through the DOE reviewing process and was disavowed and strongly critiqued by the head of the division that had issued it.¹¹

A major part of this opposition to reprocessing came from those opposed to nuclear power in general for political and philosophical reasons. They realized that it was too late to stop the present generation of reactors, but if they could stop reprocessing, nuclear power could have no long-term future. However, the most important opposition to reprocessing came from its possible connection to nuclear weapons. If there is a connection between nuclear electricity and nuclear explosives, reprocessing is the bottleneck through which it must pass. We now turn to a discussion of that matter.