Plutonium: the enigma of the nuclear age

Maybe scientists didn't think of the world as an infinite garbage can, but they often behaved as if they did. Can the new players in nuclear science regard their field in a new way?

By Peter Brogden | 1994-11-01 12:00:00

Kim Il-sung is dead. The "Great Leader" of North Korea lived through the Japanese occupation to become a skillful player in international politics, playing great powers against each other from the time of the Korean War right up to a few days before his death. The long-drawn out saga of North Korea's willingness to commit itself to the Nuclear Non-proliferation Treaty (NPT) has only been exceeded by the prevarication of the five nuclear weapons states (the United States, the former Soviet Union, France, Britain, and China) over a Comprehensive Test Ban.

It appears that the ultimate negotiating point between North Korea and the United States, as brokers for the International Atomic Energy Agency (IAEA), is that exactly what happened to plutonium extracted from the Yongbyon reactor in 1989 will remain secret, hence leaving unresolved the question of whether North Korea could have constructed a nuclear weapon with that plutonium. The uncertainty engendered by this action will ensure that Kim Il-sung's successor could continue with international political game-playing.

North Korea's power to play in this league is derived from its possession of plutonium, likely just a few tens of kilograms of it. We should remind ourselves that plutonium is the classical material of the nuclear age and that the start of the nuclear age could well be fixed at the time of governmental approval to proceed with its manufacture. In the ensuing 53 years, the world's burden of plutonium has reached about 1,000 tonnes, all of it produced in nuclear reactors. This production has employed many scientists and other workers, as plutonium is important in both nuclear weapons and power programs. In fact, it combines many of the worst-feared aspects of nuclear programs: It is highly toxic; it is inevitably produced in all civilian nuclear power reactors; and it requires elaborate safeguards to prevent diversion to secret weapons programs.

Over the past decade, new players have come into the scenes that involve nuclear weapons. These leadership changes have been more dramatic than any changes concerning the physical materials used in the warheads. Unless a concerted effort is made (both inside governments and outside) to dispose of all weapons materials-especially plutonium-they will remain a serious problem for perhaps a thousand generations.

We scientists old enough to remember the pre-nuclear age paid scant attention to the down-stream effects of our work. Certainly during our training and formative years we were not taught much about sustain-ability. We often treated the world as an infinite garbage dump. Can the new players in nuclear science regard their field in a new way?

Let's start by looking at two features of plutonium that you will not find in any science text-book. The first is connected with its name, which is generally attributed to discoverers Glenn Seaborg and co-workers, although they were not alone in naming "element 94" plutonium. It had been only a few years earlier that the outer planets of the solar system had been named Uranus, Neptune, and Pluto, so it was natural that elements 92, 93, and 94 follow suit as uranium, neptunium, and plutonium. Maybe those scientists had a grounding in classical Greek mythology. They already knew "element 94" might prove to be a "better" bomb material than uranium-235, and perhaps they decided that the attributes of the Greek god Pluto-being both the god of abundance and the god of death in the domain of Hades-made plutonium a fitting name for this element.

Soon it was discovered that plutonium would not only make better bombs (yielding bigger and more efficient bangs), but that it could generate electric power limited only by the supply of uranium.

This discovery has given rise to the idea of a "plutonium economy" based on fast-breeder reactors that can produce, from an initial charge containing enriched uranium, more plutonium than is burned in normal operation. Thus abundance would bring with it the power and riches sought by governments. Needless to say, power in this context means both electric power and diplomatic power. The Permanent Five of the U.N. Security Council, with their veto powers are, of course, also the five Declared Nuclear Weapon States of the NPT.

It is important how we, as members of Science for Peace, view plutonium in the light of these conflicting attributes. The Greeks admitted confusion between the two roles of the God Pluto. On one hand, many in the nuclear power industry advocate a "plutonium economy" as one of the few options for supplying enough electric power to meet the demands of the next century. This will entail relying on all the technologies thatareshared with nuclear weapons manufacture except actual war-head construction and delivery vehicle production.

Capital costs alone for the construction of plutonium-producing fast-breeder reactors are almost prohibitive. When added to the direct costs of safeguarding the necessary transport of plutonium from one region of the world to another, the combination has discouraged the Japanese, who until now have been one of the strongest advocates of fast-breeder development. At an Arms Control Workshop organized by Science for Peace just over a year ago, Canadian Ambassador for Disarmament Peggy Mason said that the Japanese had been surprised at the high level of public opposition to the shipment of plutonium from France to Japan and that they were curtailing their fast-breeder program. The physical characteristics of the materials haven't changed, but the way they are regarded by the Japanese has.

The change is significant. A report in the April 1994 Scientific American describes attempts by the Japanese Power and Nuclear Fuel Corporation (PNC) to "educate" the Japanese public about the risks associated with plutonium. In a modern idiom, they use a video-cartoon character, Mr. Pluto, who in one scene persuades a friend to drink a beer laced with a gram of plutonium. "Never mind," he says, "most of it will flush through your body." The report adds that Paul Leventhal of the Nuclear Control Institute in Washington has written to PNC President Takao Ishiwatari suggesting a "Pepsi Challenge," that if he really believes in the safety of drinking a gram of plutonium, he should drink it himself while on national television!

This episode highlights an attitude commonly taken by scientists who become arrogant experts: "With proper education, you will come to think as we do."

Another aspect of plutonium that has not made its way into textbooks relates to the question: "What will happen to plutonium if we leave it for our children to deal with?" Because the most weapons-desirable isotope (plutonium-239) is longer-lived than the principal contaminating isotope (plutonium-240), so-called "reactor-grade" plutonium will become weapons-grade if left long enough. As the half-lives for the isotopes are about 24,000 and 6,000 years respectively, this will not be of concern for our immediate children, but it will for those a thousand generations down the line.

Perhaps one way to relate to this sort of question is to study what our ancestors of 30,000 years ago were doing. Heidi Knecht in Scientific American, July 1994, reports on the weapons manufactured by Cro-Magnons in what is now Europe between 40,000 and 22,000 years ago. Her studies included reproducing spearpoints in order to evaluate the technology used by the artisans and to try to understand their hunting methods. Their survival depended on being able to kill larger mammals such as bison and mammoths for food, as well as deer, which would provide hides for clothing. The materials used and the careful shaping of spearpoints indicated their practical understanding of the strength of the materials, as well as their ability to communicate.

Now take ourselves forward an equal span of time, when archaeologists/forensic scientists survey our nuclear waste dumps. The strongest radioactivity will be from the remaining plutonium-239, and even if we stopped producing it today, there would still be some 400 tonnes which, at 10 kilograms a warhead, means 40,000 warheads. The dumps need only be mined-all the dangerous fission products which have bedeviled and leaked from our generation's nuclear weapons production plants will have decayed to low levels. Surely these archaeologists of the future will marvel at our progression from the use of technology for food collection and survival, to our present military-technological-industrial complex, which consumes so many resources.

The archaeologists/forensic scientists of 30,000 years from now will be looking at the isotopic abundance of our old plutonium and divining our uses and abuse of it. That is exactly what the U.S. is agreeing not to do with North Korea's old plutonium, as part of the protracted negotiations to bring an old enemy into the fold of the NPT. Has our argument come full circle? Maybe, just maybe, we could break out of it by making a commitment to nuclear science that will recognize the importance of having truly democratic participation in its control.

Just for now, we should concentrate on getting rid of as much plutonium as possible. The fantasy of a plutonium economy is receding into the future faster and, if it is to be revived, a more democratic control regime must be established over its uses. The first necessary step is to reduce the quantity on the surface of this planet to the absolute minimum. Methods for doing this have been extensively studied by teams associated with Frank von Hippel, who is now with the Interagency Task Force on Plutonium Disposition in the White House, Washington. Though their primary concern is with ex-weapons plutonium and highly enriched uranium, the extension to reactor-grade must follow. From the point of view of possible diversion to clandestine weapons programs, there is little difference between the two grades of plutonium. Even reactor-grade plutonium can be made to explode, though the yield will be small and unpredictable.

(See J. Carson Mark, "Explosive Properties of Reactor-Grade Plutonium," Science and Global Security, 1993,Vol.4, pp111-128).

Peter Brogden is a board member of Science for Peace and professor emeritus of electrical engineering at Ryerson Polytechnic University.