Yearly, the directors of the three nuclear weapons laboratories Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and Sandia National Laboratories certify the weapons designed by their labs as safe and reliable without testing. This annual certification drives the stewardship challenge. Plutonium is a particularly demanding part of that challenge because it is the component that we cannot test under conditions that produce a nuclear yield. Many of the other components can be adequately tested under simulated conditions.

Our approach to stewardship is to extend the lifetimes of pits (requalify) or remanufacture the pits in the warheads scheduled to remain in the stockpile. The United States is currently establishing a pit production capability of very limited capacity at Los Alamos. Extending the lifetimes of pits to 50 years and beyond provides a substantial financial incentive because of the high construction costs for new plutonium facilities. Certification of requalified or remanufactured pits is a major challenge for metallurgists, chemists, engineers, and weapon designers.

Because the pits in the stockpile are aging, we must significantly upgrade our surveillance. It is therefore imperative that we develop new, more-sophisticated nondestructive techniques to assess changes caused by aging. New diagnostic capabilities under development may allow detecting changes early and predicting the lifetimes of pits. Several age-related issues about plutonium concern us. Among them are surface changes caused by corrosion and dimensional changes.

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