The National Nuclear Security Administration (NNSA) must regularly assess the nation’s nuclear weapon stockpile. However, the Government Accountability Office (GAO) says the data that NNSA uses to model the stockpile’s safety and more needs to be updated.
To assess the stockpile, the agency performs plutonium experiments in a facility about 1,000 feet underground. NNSA’s objective for the Enhanced Capabilities for Subcritical Experiments (ECSE) program is to improve its ability to assess the performance, safety, and reliability of nuclear weapons without nuclear explosive testing. To do so, NNSA plans to make new measurements of plutonium during subcritical experiments by building an instrument named Scorpius to produce a series of x-ray images of the plutonium and an instrument named Zeus to measure the rate of the nuclear chain reaction.
As of March 2023, NNSA estimated that constructing both instruments and related infrastructure upgrades in the U1a facility will cost about $2.5 billion to $2.6 billion. NNSA requires both instruments by 2030 to inform plans for modernizing the nuclear weapons stockpile.
GAO’s review found that NNSA has identified risks to the ECSE program and has appropriately managed risks to build Scorpius. Specifically, NNSA identified risks to the ECSE program in four categories: integration of efforts, safety, economic conditions, and technology development. GAO found that NNSA applied appropriate processes to manage these risks for Scorpius and associated infrastructure, such as using a technical change control board to integrate the efforts to design and build Scorpius and the associated infrastructure upgrades.
GAO said NNSA used less rigorous processes to manage risks for Zeus and its associated infrastructure, resulting in a 2-year delay and increased cost. Specifically, the lack of processes to integrate the instrument and infrastructure, such as a technical change control review board, resulted in the need for additional mining at U1a to accommodate instrument design changes. While NNSA used less rigorous management processes typical of research and development programs, such as Zeus, NNSA’s program management requirements provide flexibility to use additional processes to appropriately address risks. As of May 2023, NNSA began implementing more rigorous processes to manage Zeus’ infrastructure, but NNSA has not yet adopted more rigorous processes to manage risks for the Zeus instrument, in particular related to technology development and integration. By implementing additional risk management processes, GAO believes NNSA may prevent further delays to Zeus and the associated infrastructure and ensure that it obtains necessary data for stockpile modernization.
As a result of its findings, GAO is recommending that NNSA ensure adoption of additional management processes to improve risk management of the Zeus ECSE program elements. NNSA concurred and plans to implement it by September 2025.