Annette Cary Tri-City Herald
RICHLAND — Some workers at the Columbia Power Plant experienced unexpected and significant radiation exposure during spring maintenance and refueling outage, according to the Nuclear Regulatory Commission.
According to the NRC, the exposures could have been higher if a problem had not been discovered quickly by chance.
But “no credit is given to luck,” the NRC said in its inspection report.
The NRC is considering issuing a “white” statement of offense to Energy Northwest over the incident at its nuclear power plant near Richland.
A white violation, the second lowest on the NRC’s four-step color scale, has low to moderate safety significance and may lead to further inspection by the NRC to ensure the issues have been corrected.
“Energy Northwest’s top priority is the health and safety of our employees and the public and we take this event very seriously,” said Grover Hettel, nuclear manager at Columbia Generating Station.
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The incident occurred on May 28 when the commercial nuclear plant, the only one in the Northwest, was shut down for scheduled maintenance. This was shortly before then-general manager Brad Sawatzke officially retired.
According to an NRC inspection report, radiation workers and pipefitters on the May 28 night shift were preparing to weld on heat exchanger piping cleaning highly contaminated reactor water.
After the pre-job briefing, a radiation protection technician was unable to climb onto the work platform attached to the scaffolding and left to find another technician to replace. The technician who filled in had not attended the briefing and arrived when workers were already cutting into a pipe.
Work on the pipe, including grinding, required the use of a containment glove bag to contain radioactive particles that could become airborne.
But the workers used the wrong glove bag entry fitting, and the glove bag collapsed when a vacuum system was activated. Workers turned off the vacuum system, which allowed airborne radioactivity to accumulate and escape when the glove bag was removed, according to the inspection report.
Fortunately, a radiation protection technician was monitoring work on CCTV cameras.
He immediately spotted the problem and within 30 seconds he was in the room and had ordered work to stop.
Radioactive contamination was discovered on the faces of two pipefitters, prompting the evacuation of 20 other workers in the room.
One pipe fitter had an internal dose of 961 millirems and the second an internal dose of 711 millirems.
The NRC limits exposure to 5,000 millirems per year for external and internal radiation, and Energy Northwest sets a more conservative limit of 2,000 millirems.
A radiation protection technician received an internal dose of 14 millirems. Eighteen other workers had involuntary absorptions of less than 1 millirem after passing through the area of airborne radioactive particles as they evacuated the room.
“The U.S. nuclear industry has implemented large safety margins that Energy Northwest is working on to ensure worker protections,” Hettel said. “The dose the workers received was well below the regulatory limits and administrative limits that Energy Northwest has for our workers.”
Energy Northwest failed in several respects to provide adequate radiological controls for the work, according to the NRC report.
He said Energy Northwest was lucky the radiation protection technician saw the work on a remote monitor, was experienced enough to recognize a problem, and was only 40 feet from the room.
Had the pipefitters remained in the room for an additional five minutes, they could have been exposed to more than 5,000 millirems, exceeding the NRC’s annual limit, according to the inspection report.
“While this event should not have happened, we don’t credit luck with preventing a worst-case scenario,” Hettel said. “And it was thanks to our high safety standards and thorough monitoring and surveillance processes that we had in place that allowed us to identify and resolve the situation immediately.”
Energy Northwest should have done more radiation studies the day before work began, should have prevented airborne radioactive particles, and should have had a radiation protection technician with both pipe fitters at all times.
Energy Northwest investigated and took immediate action to prevent similar issues from happening again, he said.
The NRC will hold a regulatory conference call with Energy Northwest officials at 7 a.m. PT on March 1 to discuss the incident.
The public can listen to the business portion of the meeting and then ask questions by calling 800-857-5003 and entering passcode 5204033#.
The teleconference will be an opportunity for Energy Northwest and the NRC to discuss the circumstances of the incident and ensure that the NRC has a full understanding of the information before making a decision on whether a “white violation” occurred, according to Energy Northwest.
No decisions should be made during the teleconference.
