Dr. A. David Rossin is a Center Affiliated Scholar, Center for International Security and Arms Control, Stanford University. He was President of the American Nuclear Society (1992-93) and served as Assistant Secretary for Nuclear Energy, USDOE, in 1986-87. Prior to this he was Director of the Nuclear Safety Analysis Center at EPRI and, directed and conducted research on energy and environmental problems at Commonwealth Edison Co. and Argonne National Laboratory.

1. NUCLEAR POWER AND THE FUEL CYCLE

The world really found out about the energy in the nucleus of the atom when two atomic bombs ended World War II. But even as the historic Manhattan Project developed its fearsome weapons, scientists and engineers like Enrico Fermi, Glenn Seaborg and Walter Zinn were thinking about how the energy of the atom could be harnessed for peaceful use. Within fifteen years electricity had begun to flow from nuclear power plants, but the technology has always carried the fear of, and the relationship to, the mushroom cloud.

From its inception in the 1940's, nuclear power as conceived by the United States had a closed fuel cycle. Uranium would be mined and milled, enriched in its fissionable isotope U-235 from the 0.7% found in nature, manufactured into fuel and burned in reactors to generate electricity. As it burned, some of the uranium would be converted to plutonium. Then the spent fuel would be removed and shipped to a central plant where it would be dissolved and reprocessed chemically. The unburned uranium and plutonium would be separated and could be recycled in new fuel. The radioactive fission products would be buried as waste.

By the mid-1970's, the state of the art in nuclear energy involved water-cooled nuclear reactors fueled by uranium enriched to 3 - 4% U-235. (Weapons were made with 93% enriched uranium or purified plutonium.) After generating power for three years or more, the spent fuel would be removed. It would contain very radioactive fission products, less than 1% U-235, and 1 to 2% plutonium. When discharged as spent fuel, as much as 40% of the energy would be coming from fission of plutonium atoms and the rest from the uranium.

Ideally, the plutonium would be saved to use as fuel for breeder reactors, which could burn it more efficiently and also make more new plutonium fuel than they would consume. Recycling of fuel containing plutonium in conventional reactors was regarded as an essential steppingstone before commercial breeder reactors. While the energy community saw the breeder as a necessary part of the long-term energy supply mix, there was sharp disagreement. Environmental groups saw the breeder as a danger. An unlimited source of energy, they feared, would mean more energy use and waste, leading to more global environmental degradation and also opening new risks for proliferation of nuclear weapons.

2. THE WORLD NUCLEAR SCENE IN 1975

The U. S. led the world in numbers and efficiency of nuclear power plants. The chemistry of wartime reprocessing had been adapted to the commercial fuel cycle, and experimental breeder reactors had furnished experience for the design and start of construction of a commercial-size demonstration plant. The European nations, Russia and Japan were building nuclear power plants and looking ahead to breeder reactors for the future. In 1974 the world was facing an energy crisis, dominated by a Middle East cartel that controlled the supply and world prices of oil.

Proliferation had always been a concern, and extensive research had been done on safeguarding plutonium from diversion. Technologists knew that they did not have answers to every possible threat, but they felt confident that they could design against any conceivable danger. The conventional wisdom was that plutonium separated from commercial reactor fuel could not be used to make nuclear weapons. But weapons designers and nuclear physicists recognized that it was physically possible for almost any mix of plutonium isotopes to have nuclear explosive properties.

The facts were classified SECRET, but the U. S. had actually exploded a device made of "reactor-grade plutonium" at the Nevada Test site in 1962. This confirmed the fears of specialists at the Arms Control and Disarmament Agency. Its very existence further elevated concerns about reprocessing among political advisers to both President Ford and candidate Carter. (Actually, the 1962 test was not decisive. See Sec. 4.2 below.)

On May 17, 1974, there was a nuclear explosion in India. India proved to the world that her scientists and engineers could match those of the six nuclear nations. India had refused to join the Nuclear Nonproliferation Treaty, calling it "discriminatory" because it differentiated between the six nuclear weapons nations and all the rest. India said its interest was for massive construction projects rather than weapons. She expected that her test would make her a member of that select nuclear club. It did not happen. The U. S. and the others did not want to reward any nation for going nuclear. To welcome India for testing might just defeat the real objective of preventing further proliferation.

The Indian explosion caused an agonizing reappraisal of paths to proliferation. The nuclear supplier nations formed a secret group. The U.S. put pressure on proposed French and German nuclear deals that would include enrichment or reprocessing facilities for Pakistan, South Korea, Taiwan and Brazil. Congress began work on bills that would tighten the conditions for U. S. nuclear exports. The Ford administration carried out a secret study, and five days before the 1976 election President Ford ordered a hold on startup of the new reprocessing plant until issues involving safeguards and nonproliferation could be resolved.

The basic concern was that separated plutonium would provide the key ingredient for making an atomic bomb. Reprocessing plants do produce separated plutonium. The issue that emerged was whether or not reprocessing should be permitted to proceed in certain countries, or perhaps anywhere.

3. THE CARTER POLICY

On April 7, 1977, President Jimmy Carter announced that the United States would defer indefinitely the reprocessing of spent nuclear reactor fuel. He stated that after extensive examination of the issues, he had reached the conclusion that this action was necessary to reduce the serious threat of nuclear weapons proliferation, and that by setting this example, the U. S. would encourage other nations to follow its lead.

President Carter's Executive Order also announced that the U. S. would sponsor an international examination of alternative fuel cycles, seeking to identify approaches which would allow nuclear power to continue without adding to the risk of nuclear proliferation. More than thirty nations participated over almost three years. But no new magic answer could be found.

Some other nations went ahead with reprocessing and breeder development, but high costs and loss of political support delayed plans in many nuclear projects around the world. The U. S. never regained its technological lead in nuclear energy development, its own nuclear power program had already gone from orders to cancellations, and the dream of long-term future energy security from breeder reactors faded away. The three years of uncertainty about the future had wiped away further prospects for private investments in the nuclear fuel cycle. Today, twenty years later, all U.S. spent fuel remains in storage at each plant where it was used.

4. AN EXAMINATION OF THE REASONING

4.1 Diversion Of Plutonium from Reprocessing Plants

Argument: The key issue driving the policy was the threat of proliferation by diversion of plutonium from the civilian fuel cycle. U. S. policymakers were dubious that any safeguards regime could prevent diversion of plutonium for weapons purposes.

Counter: If a nation really wanted the facility for secure energy supply, it would have the incentive to permit international monitoring. Accuracy of measurements was improving with experience, and the combination of careful material control and physical security could preclude actual diversion.

Discussion: In any large chemical process facility, quantities and flows have to be measured to control and account for material. In every measurement there is bound to be some uncertainty. Mathematical formulas used to quantify uncertainty showed that in a large plant, the uncertainty would exceed many kilograms of plutonium every month: enough to build several bombs per year. Also, the possibility of clandestine diversion could allow a government to obtain plutonium in weapons quantities without being detected. On the other hand, officials involved with policy did not accept engineering explanations of how difficult diversion would actually be, nor how serious the political dangers of such an act would become.

4.2 Use of "Reactor-Grade" Plutonium for Nuclear Weapons

Argument: Any pure plutonium, regardless of isotopic mix, can be made to explode. Therefore, any process that separates plutonium adds directly to proliferation risk. Since commercial reprocessing separates plutonium, it therefore should not be permitted.

Counter: Even before the 1970's it was known by experts that it was possible to make an explosive nuclear device from a wide range of mixtures of plutonium isotopes. Plutonium-239 is the isotope of choice for weapons. Reactor-grade plutonium is rich in the heavier isotopes (Pu-240, 241 and 242) and is not the material of choice for weapons.

The secret is no secret. It's all in college textbooks. "Production reactors" like those in the U. S. at Hanford and Savannah River had one purpose: to make weapons-grade plutonium. Target slugs of natural uranium were taken out after 10 to 16 weeks. After that time, the undesirable heavier isotopes of plutonium really start building up. Power reactor fuel spends 3 to 6 years in the reactor core, building up large concentrations of the heavy isotopes, particularly Pu-240, that make weapons design more difficult.

The problem for the weapon designer is that Pu-240 and 242 release neutrons rapidly all the time, even before a critical mass is reached. These neutrons cause premature ignition and unpredictable blast yield. Such plutonium could still produce a nuclear explosion large enough to cause serious destruction, although to equal Hiroshima would require more complex design.

Also, some of these isotopes give off more heat, requiring special cooling and causing storage problems if weapons are to be kept ready for use. However, once the decision is made to have a serious nuclear military force, the cost of the plutonium becomes only a minor part of the huge cost of warheads, bases, bombers and missiles, maintenance and command structure. With this level of national commitment at stake, why would a nation use plutonium that would make a weapon which is not highly reliable?

Most important to advanced nations, weapons are manufactured and assembled by hand, and heavy isotopes give off enough radiation that highly skilled workers would quickly reach allowable exposure limits, or face serious health risks if they continued to work. An advanced nation with commercial reprocessing could not accept such radiation risks, but a rogue nation or terrorists would not let radiation standards interfere (like the bomb builders in Tom Clancy's "Sum of all Fears").

Discussion: It is not proper to argue that certain governments which may want nuclear weapons desperately, will not (or have not!) tried almost any possible route to get them. Efficiency, reliability and cost have not always been decisive factors. But these factors would be vitally important for an advanced industrial society if its objective were to build an arsenal of military weapons to defend their nation or to attack another.

Previously classified information which showed that a nuclear explosion had been achieved at the Nevada Test Site in 1962 using "reactor-grade" plutonium was revealed on a limited basis in 1976. It had a small yield, it was an "explosive device" and not a bomb, and the purpose of the test was to verify physics parameters and not to verify that reactor-grade plutonium would explode. However, it impressed those who were told about it.

The important engineering and reliability reasons that had led all nations away from this highly irradiated material were discounted by Carter's advisors. The theoretical possibility was enough to drive their thinking to the conclusion that all stocks of separated plutonium had to be eliminated.

Nuclear experts generally took the position that a number of more attractive routes to nuclear weapons existed, and that these were the areas that called for real concern and action. But other voices entered the top-level debate. The late Albert Wohlstetter was a highly regarded consultant to the Department of Defense and Arms Control and Disarmament Agency. He wrote about possible clandestine diversion of separated reactor-grade plutonium from a reprocessing plant or stockpiles. The scenarios involved advance preparation of all manufacturing capability and weapons components, explosives and detonators. Then, if the right amount of plutonium could be diverted, fabrication of a plutonium bomb could be done in such a short time that there would not be timely warning for diplomatic actions to prevent the emergence of a new nuclear weapons nation.

Even the fact that eliminating reprocessing would only affect one possible route to proliferation, and that others were easier to conceal, cheaper and more reliable, did not deter the Carter strategists from their final narrow policy choice. This rigid policy carried serious downside risks of greater long-term energy dependence on oil and gas, as well as coal. And with the implementation of this policy America's technological lead in nuclear energy and its influence and credibility with our allies was lost.

Missing from U. S. policy thinking has been differentiation between totally different types of threats: industrialized nations, nations outside the NPT or suspected of subverting it, "rogue states" (North Korea, for example) and subnational or terrorist groups. President Carter was seeking a single comprehensive policy which could solve all potential problems with one policy initiative. However, history suggests that the issue is more complex than he recognized.

4.3 Terrorist Threats

Argument: If separated plutonium metal or oxide were shipped in commerce, terrorists could steal it and make a bomb.

Counter: Terrorist scenarios must certainly be taken seriously, because it is recognized that terrorists could get much publicity from an attempt to steal plutonium, regardless of whether or not they could make an explosive out of it. A more likely scenario for terrorists would be to threaten to release powder into the air. The actual threat to health would be very low, but the likelihood of panic would be very high indeed.

For decades, action-ready nuclear weapon components and actual weapons were routinely shipped throughout the U. S. in unmarked trucks. Shipments of plutonium oxide in Europe are carefully accounted for, packaged and sealed, and transported under very tight security. Japan has sent spent fuel to France for reprocessing. Despite emotional outcries from a number of Asian nations, the ship that carried Japan's reprocessed plutonium on its voyage home was thoroughly safeguarded and monitored under stringent international controls.

4.4 Setting an International Example

Argument: For the U. S. to set a convincing example, it was necessary to treat all nations alike. And obviously, if it wanted others to refrain from reprocessing, it had to refrain itself.

Counter: In fact, other nations wanted their fuel reprocessed in order to use, save or barter their plutonium, and so that they could dispose of their nuclear waste and thereby satisfy environmental concerns.

Discussion: The U. S. could have offered commercial reprocessing services, just as Britain, France and Belgium did. This action would have offered a clear way to reduce perceived risks related to reprocessing in unstable regions of the world.

Actually, some Europeans leaders suspected that the U. S. (with its huge coal, oil and gas resources) was trying to get an economic advantage in energy, and by calling for them to abandon their programs, might be trying to recover its world leadership in nuclear energy. They believed this, because to them, the Administration's economic and proliferation arguments against reprocessing did not make sense.

Proliferation threats from advanced nations, rogue states and terrorists were not differentiated. Jimmy Carter wanted a comprehensive policy that solved all proliferation problems. The goal was a leakproof regime, but that was unrealistic in view of all the alternative paths to nuclear weapons. Far from being comprehensive, the Carter policy affected only possible path: from commercial reprocessing in industrialized nations. These nations had better, more secure and secret ways if they wanted to make nuclear weapons.

4.5 Economics and Arithmetic

Argument: Reprocessing was not economical, so it should not proceed, or at least it should be delayed for decades.

Discussion: Economic analyses played a decisive role in reaching the decision to stop reprocessing. A key position of President Ford's Fri Report and of the Ford Foundation/Mitre Corporation (F/M) panel that advised Jimmy Carter was that reprocessing offered little economic benefit. Therefore, the reasoning went, if it carried any additional proliferation risks, it was logical to prevent it.

Actually, most of the computer analyses did show a break-even or slight advantage to reprocessed mixed plutonium-uranium oxide (MOX) fuel relative to newly mined and enriched uranium fuel costs. However, fuel cost was only 1/4 of nuclear power generation cost, and generation cost was less than half of the consumer's electricity price. Small savings in fuel cost were not the important consideration.

More important was the fact that utilities were seriously concerned about long-term factors, like nuclear waste disposal and ultimate utilization of plutonium in breeder reactors, which made closing of the nuclear fuel cycle very important to their planning. Although the arithmetic the modelers used in calculating relative fuel costs may well have been right, real economics includes much more than fuel cost.

Utilities saw nuclear power as essential for the future. The President was ordering utilities to cut back on burning oil and gas. Failure to close the fuel cycle, demonstrate waste disposal and keep the option open for breeder reactors meant that nuclear power's future was no longer than that of oil and gas.

In any case, the investors and their customers should have had more say about whether or not they wanted to take that financial risk, rather than having government preempt market decisions.

Economic modeling studies made for the F/M panel also indicated that energy costs would represent a large absolute amount over time. However, the leading F/M economist argued that large as they were, energy and its costs represented but a small fraction of the total economy. So, the F/M panel decided that a limited saving in electricity costs should not be a crucial factor in ultimate decisions.

More telling however, was the conclusion of the modeling studies that the cost of delay of 10, 20, or even 30 years did not have a serious effect on the overall economy over 100 years. (This would have been very debatable if experienced energy experts had reviewed the findings, especially since future costs and benefits were heavily discounted.) Thus the recommendation to defer reprocessing and the breeder was easy, because it was seen to carry no great penalty that the general public could see.

4.6 Direct Disposal vs. Reprocessing: Proliferation Risk Assessment

Argument: Direct disposal by burying spent fuel eliminates any possibility of reprocessing and separating plutonium.

Counter: In commercial facilities today plutonium stays under international safeguards.

Discussion: The realistic risks of proliferation for direct disposal of spent fuel can be compared with risks from safeguarding separated plutonium, making it into MOX fuel, burning it in power reactors, and returning it to the spent fuel standard.

Proliferation risk with direct disposal of spent fuel is a longer term matter. A lot of the radioactivity of the fission products decays away in a couple of decades. Therefore, an underground repository filled with spent nuclear fuel could actually become a rich mine of plutonium ore. At some future time, the radioactivity, while not trivial, would be low enough to permit rather unsophisticated mining and reprocessing to separate the plutonium.

The proliferation risk of the "plutonium mine" is regarded to be low. However it is not to be ignored. If proliferation is really a long-term concern, the risk of direct disposal of spent fuel becoming a "plutonium mine" actually becomes greater than from separating, storing and burning reactor-grade plutonium. With time, the intense radiation from the fission products in the spent fuel decays to levels where a terrorist group (let alone a nation) could separate the plutonium with a much less sophisticated and shielded process.

4.7 Conclusions

To the F/M panel and the Carter administration, the conclusions were obvious: