Science News (May 23, 1998)
Reactor Bugs
Janet Raloff

Bacteria can thrive in extreme environments, including the highly irradiated pools of water holding used nuclear fuel rods at the Energy Department's Savannah River Site in Aiken, S.C. Microbes inhabiting this storage depot for test reactor fuel may prove a headache for nuclear waste managers, a new study finds, because the bacteria can corrode and crack the fuel's metal housings.

Though microbiologists have indicted acid-producing biofilms—goo-covered communities of bacteria—in the pitting and perforation of surfaces ranging from water mains to offshore oil platforms (SN: 7/20/85, p. 42), Savannah River's waste managers had expected their system to be immune. Not only do they keep the pools virtually free of nutrients, but the fuel rods in them were supposed to be removed in just a few months.

However, with no program in place for disposing of high-level waste and the site's fuel-recycling program on hold, some fuel rods have remained in storage at Savannah River for 30 years. So Carl B. Fliermans' team at Westinghouse Savannah River Co., which manages the site, decided to probe the pools for bacteria. At the American Society for Microbiology meeting in Atlanta this week, the group reported finding up to 10 million bacteria per milliliter of water.

The team also took clean samples of the fuel rods' metal alloys and submerged them in the pools. Colonies of biofilm-producing microbes formed on the pieces within 3 weeks; after a year, they had induced microscopic pits and fissures. Though even the oldest fuel rods show no overt corrosion, all will be closely monitored. The intent, Fliermans told Science News, "is to nip this thing in the bud"—perhaps using ultraviolet treatments or water filtering.

Bugs in the Reactor (1959)