Published: Friday, June 12, 2009
Radioactive wasp nests must be cleaned up
YAKIMA -- Workers at the nation's most contaminated nuclear site are conducting a sting operation to dig up radioactive wasp nests that could number in the thousands.
Mud dauber wasps built the nests, which are largely inactive now, at south-central Washington's Hanford nuclear reservation in 2003. That's when workers finished covering cleaned-up waste sites with fresh topsoil, native plants and straw to help the plants grow -- creating perfect ground cover for the insects to build their nests.
Fortunately for the wasps, nearby cleanup work also provided a steady supply of mud. Today, the nests are "fairly highly contaminated" with radioactive isotopes, such as cesium and cobalt, but don't pose a significant threat to workers digging them up.
The wasps, not radioactive, are long gone. They don't reuse their nests when they colonize each spring.
"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 U.S. Department of Energy. "You don't know what you're going to run into, and this is probably one of the more unusual situations."
The wasps collect small pieces of mud to build nests for their eggs. In this case, they built their nests in a 75-acre area around H reactor, pulling the mud from the bottom of a storage basin that once held irradiated nuclear fuel.
The steady cleanup work in the area also provided a steady supply of mud for the wasps, said Scott Parnell, Washington Closure's project manager for work near H Reactor. In one 6-acre area, the nests are so congested that workers can barely walk without stepping on one.
Mud dauber wasps built the nests, which are largely inactive now, at south-central Washington's Hanford nuclear reservation in 2003. That's when workers finished covering cleaned-up waste sites with fresh topsoil, native plants and straw to help the plants grow -- creating perfect ground cover for the insects to build their nests.
Fortunately for the wasps, nearby cleanup work also provided a steady supply of mud. Today, the nests are "fairly highly contaminated" with radioactive isotopes, such as cesium and cobalt, but don't pose a significant threat to workers digging them up.
The wasps, not radioactive, are long gone. They don't reuse their nests when they colonize each spring.
"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 U.S. Department of Energy. "You don't know what you're going to run into, and this is probably one of the more unusual situations."
The wasps collect small pieces of mud to build nests for their eggs. In this case, they built their nests in a 75-acre area around H reactor, pulling the mud from the bottom of a storage basin that once held irradiated nuclear fuel.
The steady cleanup work in the area also provided a steady supply of mud for the wasps, said Scott Parnell, Washington Closure's project manager for work near H Reactor. In one 6-acre area, the nests are so congested that workers can barely walk without stepping on one.
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