The National Nuclear Security Administration (NNSA) mismanaged development of two machines used to measure the explosive power of nuclear weapons, leading to program delays and cost overruns, the Government Accountability Office found in a recent report. 

To continue its long-running program to test the effectiveness of nuclear weapons without actually detonating one, the NNSA established the Enhanced Capabilities for Subcritical Experiments (ECSE) program “to assess the performance, safety, and reliability of nuclear weapons without nuclear explosive testing.”

The program relies primarily on two new instruments: one named Scorpius designed to produce X-ray images of plutonium used in a nuclear-weapon primary stage and another named Zeus, which is designed to measure the rate of the nuclear chain reaction, the GAO said in a report published Aug. 30.

“NNSA has not appropriately managed risks while designing and building the Zeus instrument and constructing the associated infrastructure upgrades to ensure that Zeus will meet requirements to make measurements of the rate of the chain reaction in subcritical experiments,” GAO found. “Accordingly, NNSA has experienced delays and cost increases.”

As of March 2023, NNSA estimated that constructing both instruments and related infrastructure upgrades in the U1a facility at the Nevada National Security Site will cost between $2.5 billion and $2.6 billion, GAO found. 

NNSA needs both instruments by 2030 to “inform plans for modernizing the nuclear weapons stockpile,” the agency said in its report.

The NNSA acknowledged and quantified some of these delays in March, when it released its budget request for fiscal year 2024. Officials at the sites and headquarters discussed the difficulties the projects face at the Exchange Monitor’s Nuclear Deterrence Summit in February.

This story first appeared in Defense Daily affiliate publication Weapons Complex Morning Briefing.