Entergy Vermont Yankee in Vernon. (Zachary P. Stephens/Reformer)
Tuesday June 19, 2012

VERNON -- The Vermont Yankee nuclear power plant was reduced to about 36 percent power output Monday after smoke was detected in the reactor building.

At about 1 p.m., there was a reported electrical failure in one of the two motor generator sets, which controls the reactor's power by varying the flow of the reactor cooling water, said Vermont Yankee spokesman Rob Williams.

According to Williams, the malfunction wasn't safety related and he stated that the public wasn't in any danger.

"This is not related to plant safety," he told the Reformer. "The other motor-generator set is operating normally and the plant will remain online at the reduced power output until the investigation of what happened is complete and proper repairs are made."

Williams said when operators noticed the smoke, they made the decision to reduce the plant's power output.

This the second time in the past nine months the nuclear reactor had to reduce its power output.

In September one of the plant's two recirculation pumps, which controls the same cooling water, caused an electrical malfunction that reduced the plant's output to about 46 percent.

"We're not sure at this time if it's the same problem that caused the malfunction this fall but we're still looking into it," Williams said. "As with all these components previous experience will be considered in the investigation, which is just getting under way."

Ray Shadis, technical

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consultant for the New England Coalition, which opposes Yankee's continued operation, said the problem points to a deficiency in the plant's corrective action plan and the extent of its condition review process.

There have been numerous mechanical and structural failures at the plant since a 20-percent increase in power output was approved in 2006, Shadis said. The list includes the high-pressure coolant injection system, the turbine stop valves, the steam condenser, pipes carrying radionuclides, the cooling towers, the feedwater system and now the motor generators.

"The image that emerges is they are beating a tired old horse and trying to make it into a racehorse," he said. "It looks from the outside like a whole lot of nickel-and-diming on maintenance."

Shadis questioned if the technicians had properly examined the prior electrical problems during the plant's refueling in October, when the pumps were scheduled to be repaired.

"When you do get a failure, what is indicated is that you go through the similar systems," said Shadis. "Had they done that, there is a great likelihood they would not have had this failure."

Josh Stilts can be reached at jstilts@reformer.com, or 802-254-2311 ext. 273.