The Nuclear Regulatory Commission is sending a special team to the Millstone Power Station today to investigate an accidental spike in power that occurred at a reactor there more than a week ago.

Earlier this month, a reactor operator at Unit 2 caused a spike in power that his control room crew failed to prevent from escalating as soon as they should have, the federal regulator and company said.

Such special inspections are rare and occur a handful of times a year across the country, said Neil Sheehan, a spokesman for the NRC.

"It's not something we do every day," Sheehan said.

"There are enough questions about the way the operators performed and the oversight that was present that we want to take a closer look at it. We want to learn more about decision-making by control room operators, as well as the oversight of those operators."

The operators at the Dominion-owned nuclear complex in Waterford still had all the safety systems available to shut down the reactor, and did not need to, Sheehan said, but the mistakes, once reviewed, could result in fines, violations, orders or actions against individual operators.

On Saturday, Feb. 12, Dominion operators in the control room at the Unit 2 reactor had reduced power from 100 percent, the normal level, to 88 percent in order to test valves in the turbine. The turbine converts steam energy into electricity through a generator.

When one of the control room operators pushed a control button in the wrong direction, the power began to increase, said Skip Jordan, Millstone site vice president for owner Dominion, in a conference call with The Day. In 90 seconds, the power spiked to 96 percent, Jordan and Sheehan said.

"You shouldn't have an unexpected power increase at any time ever," said Jordan. "There should have been other checks and balances in there that would have prevented the power increase that we saw."

The situation did not pose any risk to the public because the reactor was at reduced power when it occurred, said Sheehan. This was the first time, however, that such a lapse occurred at Millstone since Dominion bought the nuclear complex in 2001, Jordan said.

Dominion is investigating the cause and is calling upon other control room operators from the company and two outside power stations to help, said Jordan.

The control room workers involved included two operators, a supervisor, a shift manager and his technical adviser and a sixth person responsible for overall reactor oversight, Jordan said. He likened their interaction to the cooperation of a crew piloting a plane.

The missteps extended beyond pushing the control button the wrong way, Jordan, Dominion spokesman Ken Holt and Sheehan said.

When the power increase occurred, the shift technical adviser did not correct the reactor operator, Sheehan said. While this was taking place, there was also a lowering of reactor coolant average temperature, which should not occur. And the crew had to re-set the set points more than once to keep the reactor from automatically shutting down, he said.

Reviews of logs and interviews with the crew will be part of the inspection begun by the NRC's on-site inspectors. An NRC Region I specialist inspector was sent to the site soon after the event, as well, Sheehan said.

Once the NRC completes its inspection, it will issue a final report within 45 days.

p.daddona@theday.com