MONTPELIER, Vt. (AP) – A Vermont Yankee nuclear plant component believed by some to be at risk for cracking if the plant is allowed to boost its power output is doing so already, plant officials acknowledged Friday.

Workers at the plant, which is in the midst of an outage to refuel and get modifications needed to produce up to 20 percent more power, replaced four welds in the steam dryer as a result of the problem, the plant’s law firm wrote in a letter to the Public Service Board.

The repairs to the steam dryer are not expected to affect the approximately four-week expected length of the refueling outage, or the plant’s plans to boost its power output.

The reliability of the steam dryer has been raised as an issue by critics of the power boost, including the nuclear watchdog group New England Coalition. Steam dryer cracking has been a problem at other plants’ of similar design to Vermont Yankee after they have increased their power output.

Jay Thayer, Entergy Nuclear’s site vice president for Vermont Yankee, said the cracks at Vermont Yankee were not in parts of the steam dryer that had caused problems at other plants.

“These were in non-stressed areas of the dryer that are not exposed to heavy steam flows,” Thayer said in a statement released by the plant. “In fact, the components of the dryer that carry most of the load – the ones that presented the problems at other plants – are in good shape. However, in accordance with our uprate engineering analysis, those will be replaced with heavier steel plates.”

The plant’s planned increase from 540 to 650 megawatts rated capacity has been conditionally approved by the Public Service Board and is undergoing review by the federal Nuclear Regulatory Commission.

A key issue raised by the New England Coalition is how thorough an inspection the 32-year-old reactor will get before it is allowed to increase the stresses on various plant components to produce more power.

Coalition leaders have said that when the NRC reviews a proposal for such a power increase, it usually does a paper review of reports from the plant, rather than a top-to-bottom physical inspection.

The cracks in the steam dryer were found by inspectors from General Electric, Vermont Yankee’s original designer, plant officials said. “A Nuclear Regulatory Commission inspector has performed a review of the inspection results,” the plant said in a press release.

Arnie Gundersen, a former nuclear industry engineer who has been acting as an expert witness for New England Coalition in Public Service Board hearings, said in an e-mail sent to media outlets Friday that the discovery pointed out the need for more thorough inspections at the plant – particularly before it gets permission to increase its power output.

Gundersen said that during the board hearings, Vermont Yankee and nuclear engineer William Sherman of the state Department of Public Service “touted how thorough the VY in-service inspection program was. Yet these cracks went undetected for years.

“So much for the theory that the plant has been well inspected for the last 30 years,” Gundersen added. “Just another reason we need an independent inspection of VY.”

Plant officials said the four three-inch weld sections were removed and rewelded. Both locations were then stiffened with steel plate.

Two other cracks – one of them 14 inches long – were deemed “inconsequential.” Plant officials said they would take no immediate action to repair them but would check them during future Vermont Yankee outages.

AP-ES-04-16-04 1744EDT