Options and choices in the disposition of excess weapon plutonium

Abstract

More than 50 tons of weapon-related plutonium (WPu) is expected to become excess and available for disposition by the year 2003 in Russia and a similar amount in the United States. Per two reports from the Committee on International Security and Arms Control of the National Academy of Sciences (1994 1 and 1995 2), the hazard of theft and incorporation into nuclear weapons impels us to guard this Pu carefully and as soon as possible to transform it into a form less accessible for use in nuclear weapons. To this end, CISAC adopted the 'Spent Fuel Standard' for the disposed WPu, which, if met, renders the WPu no greater hazard per kg than the much larger amount of reactor Pu in the form of spent fuel, since CISAC finds that separated RPu can be used for nuclear weapons with little additional difficulty beyond that posed by separated WPu. Many disposition routes can be eliminated on the basis of cost or other metric. The two principal survivors (of about equal cost and difficulty for the United States) are the partial burning of WPu as MOX and the direct vitrification of WPu (as oxide) with high-level 'defense wastes'. Both these approaches should be pursued urgently, with experiments to qualify the processes, until one is selected on the basis of hard evidence. Either approach would cost about $1 B, within a factor two, to dispose of 50 tons of excess WPu. The CISAC analysis will be presented, with comments on utility of RPu in weapons, on the DOE Plutonium Disposition Study, and on 'explosive critically' in the repository.