RICHLAND — A radioactive rabbit was trapped on the Hanford nuclear reservation, but there is no sign any people were exposed to the animal.
Washington state Health Department workers with the Office of Radiation Protection have been searching for contaminated rabbit droppings. None have been found in areas accessible to the public, regional director Earl Fordham said Thursday.
Officials suspect the rabbit sipped some water left from the recent demolition of a Cold War-era building used in the production of nuclear weapons, the Tri-City Herald reported Friday.
Contaminated animals occasionally are found at the nuclear reservation, but more often they are in the center of Hanford, far from town.
The rabbit trapped at the 300 Area caught the Health Department’s attention because it was close enough to the site’s boundaries to potentially come in contact with people — if it had been caught by a dog or if its droppings were deposited in an area open to the public.
Workers first found contaminated rabbit droppings last week in the 300 Area, said Todd Nelson, spokesman for Washington Closure Hanford, the Department of Energy contractor cleaning up Hanford.
Several rabbits were trapped and the one was found to be highly contaminated with radioactive cesium. It was killed and disposed as radioactive waste, he said Friday. Routine monitoring for radioactive droppings continues.
Washington Closure has narrowed the area of possible contamination to the 327 Building. It was used during the Cold War for testing highly radioactive materials, particularly fuel elements and cladding that were irradiated at Hanford reactors as part of plutonium production for the nation’s nuclear weapons program.
The aboveground hot cells were pulled out of the building and demolition began on the structure about a month ago. One theory is that the rabbit might have been sipping water that collected in the building’s basement after water was sprayed during demolition to suppress dust.
Washington Closure has taken steps to keep other animals from getting near the building. Workers have put up a chain-link fence and removed any vegetation that might provide a rabbit snack.
They also scented the perimeter of the building with fox urine to deter animals that might burrow. Gravel and steel plates have been used to cover places that have been identified as potential sources of the contamination.
Hanford has an extensive program to check for contaminated animals. In 2009, 33 contaminated animals or animal materials such as droppings were found on the site, the Tri-City Herald reported.
In Hanford’s earlier years, contaminated animals were more common.
Liquid waste with radioactive salts was discharged into the ground near central Hanford during the Cold War. Rabbits and other animals were attracted to the salts and spread radioactive droppings across as much as 13.7 square miles of sage-covered land before the waste sites were sealed to keep out animals in 1969.
Federal economic stimulus money has been used to survey for the radioactive hot spots that remain four decades later.
In a more recent case, so many radioactive wasp nests were found spread across six acres by H Reactor in northern Hanford that up to a foot of soil was dug up to remove the nests.
The nests were built by mud dauber wasps in 2003. Water was sprayed to control dust during demolition of a basin attached to the reactor, and the mud created was collected by the wasps to build nests under straw that had been spread nearby to protect newly planted sagebrush seedlings.
There have been a couple of cases in the past two decades of contaminated animals in areas where they potentially could come in contact with the public.
In 1996, a contaminated mouse apparently crawled into a box of food collected by an employee food drive in central Hanford. It was trapped and tested in an abandoned Hanford building previously used by the Tri-Cities Food Bank.
Two years later, gnats and flies were suspected of eating a sugary coating used to fix some radioactive contamination. They then spread the contamination to waste left by workers in offices, such as banana peels and apple cores.
That required 35 tons of trash that could contain the office waste to be dug up from the Richland landfill and returned to Hanford.