Workers tackle radioactive wasp nests

12 June 2009

[Tri-City Herald, 11 June] Workers cleaning up the Hanford nuclear reservation in Washington State, USA, are having to deal with an unexpected hazard: thousands of radioactive wasp nests. The nests were all built in 2003 when water was used to dampen dust during demolition of an H Reactor basin, which once held fuel irradiated at the reactor until it was processed to extract plutonium for the US nuclear weapons program. The resulting mud attracted mud dauber wasps, which used it to build their tube-shaped nests in top soil that had been freshly-laid on other wastes sites on the reservation. The wasps abandon their nests and build new ones elsewhere each spring. Workers using excavators will dig up to one foot (30cm) of top soil from six acres near the H Reactor. In addition, another 50 to 60 individual nests will be dug up over about 75 acres of the Hanford site. "This is just an example of the issues we deal with in digging up burial grounds," said Todd Nelson, spokesman for Washington Closure Hanford, the contractor hired to clean up the area under the oversight of the US Department of Energy. "You don't know what you're going to run into, and this is probably one of the more unusual situations." He described the nests as "fairly highly contaminated." Washington Closure will spend about six weeks cleaning up the nests and trucking the waste to a lined landfill for low-level radioactive waste in central Hanford. Workers will eventually replant vegetation in the area, at a cost of about $25,000.