In the December 2000 Physics Today article Science-Based Stockpile Stewardship, by Raymond Jeanloz contains important points relevant to DOE's $5 billion-a-year "Stockpile Stewardship Program." DOE's purported rationale for the program is that it is needed for maintaining the safety and reliability of US nuclear weapons as they age. Using data from various recent studies, this article concludes that plutonium and high explosives generally grow more stable as they age! The unanswered question is why then must the Stockpile Stewardship Program be so expensive and internationally provocative?

Some selected quotes from Science-Based Stockpile Stewardship by Raymond Jeanios (Professor of Geophysics at UC Berkeley):

"The low rate at which defects [in nuclear weapons] appear suggests that a focused program of surveillance and refurbishment ought to be adequate for maintaining the stockpile throughout the foreseeable future." p. 1

"Perhaps the most important result from measurements is that Pu [plutonium-239] exhibits good crystalline order even after decades of aging." p. 4

"……on the nanometer scale, aging appears to have the same effect as a greater Ga [gallium, widely used as an alloying agent in plutonium metallurgy] concentration, in that it shifts the Pu to a more stable configuration." p. 4

"The overall finding from a variety of observations ………. is that the Pu samples not only retain long-range order but actually get closer to the ideal crystal structure with increasing age. Annealing processes, perhaps related to those countering the crystal-structure disordering, appear to counteract radiation-induced damage and mitigate the initial buildup of He [helium] quite effectively, at least for Pu in the US stockpile." p. 4

"Surprisingly, however, the high explosive used in US weapons has been found to improve systematically with age in key measures of performance, such as yielding characteristics and detonation-front velocities." p. 5

"Thus, crucial primary-stage components [i.e., plutonium pits, the triggers for modern thermonuclear weapons] that were initially subject to concern have been shown through the SSP to be robust as they age. Indeed, there is now consensus among specialists that the Pu pits in the US stockpile are stable over periods of at least 50-60 years, with the most recent studies suggesting a far longer period. More important than the indications of benign aging is the demonstration that the materials are now becoming understood in sufficient detail, and surveillance methods are becoming sensitive enough, to ensure that any signs of degradation will be observed in time to apply the necessary repairs or refurbishment." p. 5