Xcel Minnesota nuclear plant under NRC scrutiny

LOS ANGELES (Reuters) - The U.S. Nuclear Regulatory Commission was conducting a special inspection at Xcel Energy's XEL.N Monticello nuclear power plant in Minnesota, where a worker was killed on Wednesday, the NRC said on Friday.

Investigation of the worker’s death is the purview of the Occupational Safety & Health Administration. The NRC is inspecting machinery and staff performance at the plant to ensure safe operation of the 572-megawatt nuclear reactor.

A 47-year-old man was electrocuted when he came into contact with a high-voltage power line outside the plant gates, the NRC said.

The plant was already shut down following a Sept. 11 automatic tripping of power production linked to the failure of one of three main transformers at the plant in Monticello, Minnesota.

The plant is about 40 miles northwest of Minneapolis.

The electrocution caused a second of the main transformers to fail, leaving only one main transformer in operation, said NRC regional spokeswoman Victoria Mitlyng.

The public and plant employees were not in danger from the radioactive reactor at any point, Mitlyng said.

A three-member NRC inspection team was already on site to investigate plant operation linked to the Sept. 11 incident when the incident occurred Wednesday , Mitlyng said.

There was no estimate by Xcel or the NRC when the Monticello plant would be back on-line. The investigation can take 45 days but the plant’s operation is not linked to inspectors’ work, said Mitlyng.

While the plant shut down safely on Sept. 11, the NRC wants to ensure the “scope of equipment issues that occurred,” NRC regional administrator James Caldwell said in a statement.

“The power interruption (on Sept. 17) caused a system designed to cool the reactor while it is shut down to become unavailable,” the NRC said in its statement issued Friday.

Power was restored to that system in about an hour, but there was no danger of the reactor overheating because, if power had not been restored in time, plant workers could have manually reopened two values that were shut when power was lost, said Mitlyng.

The NRC does not require all three transformers to be working, Mitlyng said, but Xcel wants at least two of them up and running before plant production returns.

Reporting by Bernie Woodall; Editing by Walter Bagley