NRC begins special inspection at Constellation’s Quad Cities plant

In a June 3 news release, the NRC detailed the events at the Illinois plant:

• The first was a Unit 1 scram on May 19 caused by a degraded condition on a Unit 2 battery. In its filing to the NRC, Constellation said plant operators followed emergency protocols by manually tripping the reactor. The loss of power caused a lowering of the reactor water, because the unit’s condensate and feedwater pumps were not operating.
• The second was a May 22 Notice of Unusual Event, the lowest of the NRC’s emergency level classifications, because of a brief fire on the same Unit 2 battery. The fire was extinguished without needing to call in off-site fire assistance, and the unit remained at full power during the event.

A closer look: The NRC decided on the special inspection because of the multiple unexpected system interactions and failures during the scram, the unknown cause of the fire, and to determine if the two events were related.

Once the inspection is complete, NRC staff will document their findings in a report, which will be distributed electronically to listserv subscribers and will also be available on the commission’s website.

The NRC recently completed an unrelated special inspection at Quad Cities to review the inoperability of safety-related vacuum breakers. Once completed, the inspection report will also be made publicly available.

Quotable: “While the plant remained safe during these occurrences, an independent review by the regulator is warranted given questions related to battery problems at the root of both events,” said Jack Giessner, the NRC’s Region III coordinator. “Our inspectors will independently assess the issues; evaluate Constellation’s understanding of events and causes; and assess operator actions, the scope of the plant's assessment, and the development of correction actions.”