After more than a year of planning, highly radioactive material has been transferred from central Hanford to Pacific Northwest National Laboratory.
The 222-S Laboratory in central Hanford has been storing californium 252 in an underground concrete pit covered with water to provide shielding from its radiation. Californium 252 is a strong neutron emitter, which makes it extremely radioactive. Neutrons also are particularly hazardous to workers because they easily penetrate many materials.
Radiation from two containers of the isotope, which have been in storage since 2000, was measured at 76 and 104 rem per hour at a distance of about one foot.
"We're trying to get rid of highly radioactive sources that had a use in the past, but that we're no longer using," said John Britton, spokesman for Washington River Protection Solutions, which manages the Hanford tank farms.
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The californium once was needed as a source of radiation in a program to measure the amount of sodium in waste now stored in underground tanks that is planned to be sent to the Hanford vitrification plant for treatment.
"Moving these sources required extensive planning and preparations, including remote cameras and concrete shielding," said Don Hardy, 222-S facility manager, in a statement.
The two containers were lifted out in separate operations with a crane operated by workers behind concrete shielding. Each container was placed in a 5,000-pound transport cask for the trip across Hanford to a PNNL facility.
Crews conducted six mock ups of the process, before "the move was pulled off without a hitch," Hardysaid.
PNNL will use the californium in dosimetry calibration studies, according to Washington River Protection Solutions. Both PNNL and the 222-S Laboratory have hot cells, where workers can perform tasks with highly radioactive materials.
Transferring the californium to PNNL will save about $48,000 in surveillance and maintenance costs at the 222-S Laboratory.
It was the last material Washington River Protection Solutions was responsible for that had to be accounted for as special nuclear material, allowing the contractor to now close its nuclear safeguard program for accountable nuclear material.