U.S. May Not be Able to Maintain Nuclear Stockpile, GAO Reports

October 12, 2010 - 3:01 AM

Watts Bar Nuclear power plant

Watts Bar Nuclear Power Plant owned by the TVA (Wikipedia Commons)

(CNSNews.com) – The National Nuclear Security Administration (NNSA) may not be able to reliably maintain the nation’s nuclear stockpile in the near future, according to a report from the Government Accountability Office (GAO).

At issue is the production of a rare radioactive element known as tritium, which is used in the core of nuclear warheads to make the weapons more powerful. However, because tritium – like all radioactive elements – degrades over time, it must be replaced if the nuclear weapons are to remain in working order.

The NNSA, the agency responsible for maintaining the nation’s nuclear stockpile, has not been able to reliably produce enough tritium to ensure that America’s nuclear weapons will remain viable in the near future.

“NNSA’s inability to overcome the technical challenges and meet its original tritium production goals has raised serious questions about the agency’s ability to provide a reliable source of tritium to maintain the nation’s nuclear weapons stockpile in the future,” the GAO reported on Oct. 7.

Because tritium occurs in natural concentrations that are too small to harvest, the government must produce tritium by dipping special rods, known as Tritium Producing Burnable Absorber Rods (TPBARs), into nuclear reactors owned by the Tennessee Valley Authority (TVA).

The problem the government faces during this process is that some of the highly radioactive tritium leaks – or “permeates” – into the water used to cool the reactors. Because that water is taken from (and returned to) natural sources, the federal government regulates how much radioactive material can permeate the reactor and be dumped back into the environment.

At the Tennessee TVA plant where tritium is produced – the Watts Barr reactor near Chattanooga – the amount of tritium that regularly permeates the reactor and leaks into the cooling water is more than four times the allowable amount, forcing the government to scale back tritium production.

“[T]ritium is still leaking from the TPBARs at higher-than-expected rates,” reported the GAO. “As a result, significantly fewer TPBARs than planned are being irradiated in the reactor, which has considerably reduced the amount of tritium NNSA is producing.

“To keep the total amount of tritium released into the reactor coolant below regulatory limits, TVA has limited the number of TPBARs being irradiated” there, the GAO said.

To counteract this problem, the NNSA and TVA have planned to expand the irradiation of TPBARS to other nuclear facilities beyond the Watts Bar reactor.

The two agencies are also planning on building a holding tank at the Watts Barr facility to contain the irradiated cooling water, allowing the government to better control how much of the water to pump back into the Tennessee River.

“NNSA and TVA officials told us that they are considering the construction of a large holding tank at the Watts Bar 1 reactor that could be used to more effectively manage the presence of tritium in the reactor coolant,” reported the GAO.  “A large holding tank will enable TVA to better control the timing of

releases of coolant containing tritium.”

The Watts Bar nuclear generating station is in Rhea County, Tenn., between Chattanooga and Knoxville.

Currently, the government meets its tritium needs by using tritium from warheads dismantled after the end of the Cold War. That supply, however, is quickly running out, meaning that the government’s tritium production problems could soon pose a problem for maintaining the nation’s nuclear weapons.

The GAO has previously estimated that tritium from dismantled warheads would only last through 2012.

“NNSA is meeting current requirements through a combination of harvesting tritium obtained from dismantled nuclear warheads and producing lower-than-planned amounts of tritium,” GAO said.

“However, tritium in the stockpile as well as in NNSA’s tritium reserve continues to decay, making increased production of tritium critical to NNSA’s ability to continue meeting requirements,” reported the GAO.

Due to the complex technical problems the government has faced producing the tritium it needs, it is unlikely that it will be able to meet its needs in the future, meaning that it could face shortages if it does not reliably increase production. The leaking of tritium from the nuclear reactors where it is made poses the most significant problem for the government as it tries to increase its tritium manufacturing capabilities.

“While NNSA has taken steps to attempt to solve the tritium permeation problem, it is unlikely that anything less than a complete redesign of the TPBARs will solve the problem,” the GAO concluded. “Unfortunately, existing supplies of tritium in the stockpile and the tritium reserve are unlikely to fulfill requirements for the time a complete redesign would take.”

“It is also not clear that a redesign would solve the problem since NNSA does not fully understand the reasons behind tritium permeation,” the GAO report said.