March 17, 2014

DNFSB CALLS ON DOE TO UPGRADE HANFORD TANK FARMS’ VENTILATION SYSTEMS

By ExchangeMonitor

The Defense Nuclear Facilities Safety Board is calling on the Department of Energy to upgrade the ventilation systems at Hanford’s double-shell tank farms to reduce the risks posed by flammable gases. In a formal recommendation sent to the Secretary of Energy in late September, and publicly released yesterday, the Board said that “safety-significant active ventilation” of the double-shell tanks is needed to ensure the removal of flammable gases from the tanks’ headspace. “A significant flammable gas accident would have considerable radiological consequences, endanger personnel, contaminate portions of the Tank Farms, and seriously disrupt the waste cleanup mission. Further, the Board believes that actions are necessary to install real time monitoring to measure tank ventilation flowrates as well as upgrade other indication systems used to perform safety-related functions,” the recommendation states.

The Board has long questioned DOE’s current use of a specific administrative control for flammable gas monitoring. While a review conducted over the past year found some improvements have been made to the SAC, it remains “inadequate as a credited safety control,“ the Board’s recommendation states, adding, The SAC is less reliable than an engineered feature, remains susceptible to undetectable false low readings, and lacks independent verification.” The Board also noted that DOE’s schedules for making upgrades to the double-shell tank farms’ ventilation systems continues to slip. DOE had planned to complete upgrades to three of the five ventilation systems by Fiscal Year 2014, but a review conducted in June found that this schedule was no longer “realistic,” the recommendation says. “DOE’s current path forward is to upgrade only one of the DST ventilation systems (AY/AZ Tank Farm) by fiscal year 2015 to support mixer pump testing that is currently anticipated in 2016. No near-term procurement or installation plans are in place for the four other DST ventilation systems,” the Board said, adding, “Similarly, no plans or activities are proposed to upgrade the installed non-safety instrumentation systems being used in safety-related applications (e.g., the level indication systems for the DST annuli and the double container receiver tank).”

DOE is reviewing the Board’s recommendation, Lori Gamache, a spokeswoman for the Department’s Office of River Protection at Hanford, said in a written response yesterday. “We value input from the Board. We are committed to maintaining safe operations at the Hanford tank farms, including protecting our workers, the public, and the environment,” Gamache said. To read the full recommendation, please click here.

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