A newly released JASON study says plutonium in the U.S. nuclear weapons stockpile is aging slowly and that observed degradation does not currently threaten weapons performance.
The March 25 study, Plutonium Aging: Executive Summary, was conducted by JASON – a scientific advisory board for the U.S. military – at the request of Congress to assess research into the lifetime of plutonium “pits,” the fissile centers of nuclear warheads. The study found that plutonium properties change gradually with age but that those changes “do not call into question present weapons performance.”
Environmentalist group Nuclear Watch New Mexico pointed out in an emailed press release over the weekend the findings contrast with language in the National Nuclear Security Administration’s January draft Pit Production Programmatic Environmental Impact Statement, which cited plutonium aging as a risk requiring additional production capacity. The group said the findings undermine NNSA’s stated justification for its pit-production expansion.
Nuclear Watch New Mexico obtained the previously redacted executive summary through a Freedom of Information Act request after just last week filing suit against NNSA and DOE for redacting the study.
NNSA’s draft environmental review said existing pit-manufacturing capability was insufficient to meet requirements and that additional capacity was needed both to meet a congressional production mandate and “to mitigate risks associated with plutonium aging.” It also said many aging pits would have to be replaced to maintain a safe and reliable stockpile.
The JASON study does not conclude that additional pit production is unnecessary. Its overarching recommendation calls for NNSA and its laboratories to establish pit-production capabilities that “may be needed” to address future aging-related issues. It also recommends continuing research and accelerating subcritical experiments at the Enhanced Capability for Subcritical Experiments, or ECSE, to reduce uncertainty.
“The most recent JASON study confirms NNSA’s longstanding position that further scientific investigation is needed to understand plutonium aging. Given the importance of the nuclear stockpile to America’s national security, it would be irresponsible to delay the execution of NNSA’s two-site solution, as mandated by Congress,” an NNSA spokesperson told Exchange Monitor.
JASON said updated assessments of the relationship between pit age and weapons performance are on track for fiscal 2030. It recommended that future research be rigorously documented and externally reviewed, particularly when statistical analyses are used in national-security assessments.