GAO Finds Problems in Tritium Production

Daniel Horner

Technical problems have prevented the Department of Energy’s National Nuclear Security Administration (NNSA) from producing as much tritium as it planned, the Government Accountability Office (GAO) said in a report released last month.

Although the NNSA currently is meeting the tritium requirements for the U.S. nuclear weapons stockpile, “its ability to do so in the future is in doubt,” said the GAO, the investigative arm of Congress.

Tritium is a radioactive gas used to boost the explosive power of nuclear weapons. Because it decays at a rate of 5.5 percent a year, supplies of it have to be replenished periodically from either retired weapons or new production.

According to the GAO, “Although the number of nuclear weapons in the U.S. stockpile is decreasing, these reductions are unlikely to result in a significant decrease of tritium requirements and will not eliminate the need for a reliable source of new tritium.”

The tritium for the U.S. arsenal is being produced by irradiating special fuel rods, known as Tritium-Producing Burnable Absorber Rods (TPBARs), in Watts Bar-1, a nuclear power reactor owned and operated by the Tennessee Valley Authority (TVA), a federal corporation. Tritium is then extracted from the TPBARs in a facility at the Energy Department’s Savannah River Site in South Carolina.

TPBARs were first irradiated at Watts Bar in 2003.

The technical problem that is the focus of the GAO report is tritium “permeation” from the TPBARs into reactor coolant water at a rate that is higher than expected. The NNSA has noted the problem in budget documents, but in an interview last year, the manager of the NNSA’s Savannah River Site office said the main issue was the potential impact on reactor operation rather than on tritium production. (See ACT, June 2009.)

Because regulations for nuclear power reactors set a ceiling on the amount of tritium that can be released into the coolant, the TVA has limited the number of TPBARs loaded into Watts Bar-1, the GAO said. As the GAO noted, the Energy Department’s agreement with the TVA allows it to use two additional TVA reactors, Sequoyah-1 and -2, for tritium production.

However, as the NNSA put it in a letter to GAO commenting on a draft of the report, “Both TVA and NNSA would experience programmatic and operational benefits from keeping tritium production in one reactor, and will be working to achieve this goal. Nevertheless, NNSA does have this backup plan that can meet mission requirements with existing technologies and assets.”

The GAO said, “While we are encouraged that NNSA and TVA are working together to increase the number of TPBARs being irradiated, continued uncertainty about NNSA’s and TVA’s ability to irradiate additional TPBARs in a single reactor while not exceeding limits on the amount of tritium released into the environment raises doubts about the program’s ability to provide a reliable supply and predictable quantities of tritium over time.”

From the beginning of the program, some tritium permeation had been expected, NNSA spokeswoman Jennifer Wagner said in an Oct. 29 e-mail to Arms Control Today. The higher-than-expected permeation was initially observed in the summer of 2004, she said.