Energy Northwest is temporarily barred from sending waste to a commercial disposal site at Hanford after a shipment in November had more radioactivity than reported.
The cask of low-level radioactive waste was rejected at the US Ecology disposal site on Hanford land Nov. 9.
Workers at the disposal site surveyed the package for radiation and measured it as seven times higher than the shipping manifest for the package declared, according to Energy Northwest.
The Nuclear Regulatory Commission announced on Monday that a three-member team would spend this week on site evaluating Energy Northwest’s analysis of the cause of the incorrect measurement and its plan of corrections.
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The cask contained contaminated filters from routine vacuuming of the used fuel pool at the Columbia Generating Station, Energy Northwest’s nuclear power plant near Richland. The cask, which was about 7-feet tall and 6-feet in diameter, weighed about 45,000 pounds and was driven 10 miles to the US Ecology site on a flatbed truck.
Both the Columbia Generating Station and the US Ecology disposal site are on leased land on the federal Hanford nuclear reservation.
The rejected cask was driven back to the Columbia Generating Station, where it remains.
A day later the Washington State Department of Health notified Energy Northwest that its disposal permit for US Ecology had been suspended. The suspension can be lifted when state officials approve a written plan of corrections prepared by Energy Northwest and conduct an on-site inspection at the nuclear plant.
Energy Northwest should have the written report prepared next week, said spokesman Mike Paoli. But he warned that with the holidays it could take as long as a month for Columbia Generating Station to be cleared to resume waste shipments.
The plant sends low-level radioactive waste, such as rags, protective clothing and tools, intermittently to US Ecology. The nuclear plant has ample space to store the waste until shipments resume, Paoli said.
The US Ecology facility accepts low level radioactive waste, some of it mixed with nonradioactive chemicals, from hospitals, universities, laboratories, nuclear power plants and other institutions for landfill disposal.
Although the radioactivity was not correctly reported for the Nov. 9 shipment, it remained at levels within occupational health standards for workers handling the heavily shielded cask, Paoli said.
Energy Northwest will be looking at how accurately the process was followed at the nuclear plant for calculating radioactivity in low level waste, he said.
“While there was no undue risk to the public, had a transportation accident occurred, there was a potential that members of the public could have been exposed to radiation levels in excess of NRC regulatory limits,” said Kriss Kennedy, the NRC regional administrator.
Most of the route from the Columbia Generating Station to US Ecology is across the secure portion of Hanford that is closed to the public. The shipping container met transportation standards.
The NRC inspection should provide a better understanding of the circumstances of the event and the weaknesses in Energy Northwest’s packaging and preparation of radioactive waste shipments revealed by the incident, Kennedy said.
NRC should have a public report finished 45 days after the inspection.