Energy Northwest today determined its declaration of an unusual event at Columbia Generating Station, submitted Thursday to the Nuclear Regulatory Commission, was unnecessary.
Upon further review, Columbia officials concluded that the hydrogen burn, a less than one-second "puff," in the turbine building posed no risk to the normal level of plant safety, according to a news release.
Though the declaration had no association with the reactor building or radiation, "the decision to declare an unusual event reflected the conservative safety culture of the U.S. nuclear industry," Energy Northwest stated in the release.
On Thursday, a small amount of residual trapped gas ignited and extinguished itself in less than a second when workers cut into a pipe, according to the release.
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No one was injured, but Energy Northwest declared an unusual event and evacuated a crew of approximately two dozen workers from the immediate area as a precautionary measure, according to the release.
Work resumed in the area following a safety inspection, the release stated.
Columbia powered down April 2 in preparation for its biennial refueling and maintenance outage, the release stated.
The outage is scheduled to be completed by mid-June.
An unusual event is a classification describing a condition at a commercial nuclear power plant or its surroundings that potentially could compromise the normal level of plant safety, or that warrants increased awareness by plant staff, Energy Northwest said.