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Leftover nuclear material threatens international security

STANFORD -- Russian nuclear materials once protected by elite Soviet troops may now be guarded by grandmothers wielding cucumbers.

Stanford nuclear physicist and arms control expert Wolfgang Panofsky used this anecdote, told to him by an unnamed official in the Russian nuclear regulatory ministry recently, to dramatize his contention that the stockpiles of nuclear material remaining in the United States and Russia after the dismantling of atomic arsenals pose a "clear and present danger to national and international security."

Panofsky, the former director of the Stanford Linear Accelerator Center, related his views on this disturbing post-Cold War reality to approximately 100 attendees of a public lecture at Stanford's Memorial Auditorium on July 28, given in association with the Marcel Grossman Meeting on General Relativity that was held on campus.

The "physical heritage of the Cold War" consists of huge stockpiles of dangerous chemical and nuclear materials.

The United States' first efforts in disposal of chemical weapons have proven complicated and costly, Panofsky reported. Six to seven percent of the U.S. supply of such weapons has been destroyed on Johnston Island (near Hawaii) in the Pacific Ocean, at a cost of approximately 1 billion dollars. This process was discontinued, however, because of concerns regarding the safety of transporting the materials.

Nuclear materials represent the greatest security threat, Panofsky said. Existing arms control agreements regulate only "delivery vehicles," such as missiles, aircraft and submarines. They do not account for the disposal of the large quantities of fissionable nuclear material in the missile warheads, Panofsky pointed out. Storing, disposing and destroying this material will cost "several billion dollars" and take several decades. In the meantime, Panofsky warned that existing nuclear material is poorly guarded and accounted for, particularly in the former Soviet Union.

Panofsky estimated that 100,000 kilograms of highly rich plutonium, produced for use in nuclear weapons, exists in the United States and the former Soviet Union. This material represents a much bigger security risk than the few kilograms of material feared to have been produced by North Korea, he said. (A few kilograms of plutonium is enough to build a 1-2 kiloton bomb, equivalent to the Hiroshima explosion.) In addition, approximately 500,000 kilograms of highly enriched uranium produced for weapons use also exist; however, this uranium can be converted for use in nuclear power reactors, and therefore does not pose the same disposal problem as plutonium, Panofsky said.

Although plutonium was once considered as a fuel for generating electricity in nuclear reactors, it was found to be much more expensive to utilize than uranium (which is now relatively inexpensive, partially due to the conversion of weapons-grade uranium). Plutonium is "more of a liability than an asset" according to Panofsky. Unfortunately, the Russian government still wants to use plutonium in nuclear reactors and would like the United States to pay for the construction of plutonium- burning power plants, which do not even exist in the United States, he said. The attitude of the Russian government toward the plutonium is, "if it cost so much to produce, it must be worth something," Panofsky explained.

Until all nuclear material in the United States and Russia can be safely disposed, the material must be guarded from unauthorized access. Accounting for nuclear material is particularly difficult in the former Soviet Union. According to Panofsky, the United States cannot accurately estimate the amount of Russian nuclear material. "Our ignorance to within two standard deviations of the Russian inventory of plutonium is equivalent to about 10,000 nuclear weapons," he said.

Panofsky explained the problem in the former Soviet Union as "breakup, breakdown, and breakout":

In light of these dangers, Panofsky urged the United States government to take immediate action in arranging for the storage, disposal and destruction of nuclear material in the former Soviet Union, as well as in the United States.

Panofsky also discussed several proposed methods of nuclear material disposal, ranging from undersea disposal to underground detonation. Of all proposed methods, he considered only two to be feasible:

The first, "vitrification," involves combining plutonium with radioactive waste material, then sealing the mixture in glass rods. The second possible method involves running plutonium "once-through" a nuclear reactor along with uranium fuel in a low-grade nuclear reaction. This reaction would convert the nuclear material to lethally radioactive spent-fuel rods, similar to those created in nuclear power plants throughout the world. Both techniques would make nuclear material "theft-proof" by mixing it with highly radioactive materials.

The eventual process of taking nuclear material from long- term storage in spent-fuel rods to permanently dispose of the material has not yet been resolved by the world's nuclear power industry, Panofsky said. He advised that the United States should first focus on converting weapons-grade nuclear material to the spent-fuel form compatible with the wastes produced by the world's nuclear power industries.



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