Cooling tower woes continue at Vermont Yankee

The Vermont Yankee nuclear plant is suffering from another problem with its cooling towers, with leaks of more than 60 gallons of water a minute attributed to faulty packing in pipe joints, officials said Wednesday.

Spokesmen for Vermont Yankee owner Entergy Nuclear and the U.S. Nuclear Regulatory Commission said the leaks were in sections of the Vermont Yankee's east cooling tower not considered key to plant safety.

Entergy spokesman Robert Williams said Vermont Yankee was operating at 60 percent of its capacity as a precaution while the cause of the leaks is investigated and repairs made.

Late Wednesday, Vermont Yankee said the investigation of the leak discovered that three vertical support columns for the cooling tower had degraded and needed to be replaced while the packing in the pipe joint was being replaced.

The towers are used to cool Connecticut River water that is warmed as it is run through the plant's condenser. The water is cooled before being returned to the river, so that it does not raise the river temperature beyond state-imposed limits.

The cooling towers are used in the warmer months. In winter, the weather keeps the river cool enough on its own.

NRC spokesman Neil Sheehan said that "the Vermont Yankee cooling towers would normally be taken out of service in mid- to late October, with the actual timing ... based upon the temperature and level of the river."

Sheehan and Williams said it wasn't unusual to have the pipe joints — which are packed with oakum — leak. Sheehan said oakum is loose hemp or similar fiber, treated with a tar-like substance, which is used to caulk seems in wooden ships and pack pipe joints.

While some leaking is considered OK, 60 gallons a minute was deemed serious enough to warrant the power reduction and repair, they said.

While the incident was not considered serious, it follows two other problems in the cooling towers that caused big public relations headaches for Vermont Yankee:

— In August 2007, a pipe six feet in diameter carrying water through the cooling tower broke and the tower supporting it collapsed, and dramatic photos circulated showing thousands of gallons of water spewing onto the ground.

— In July 2008, it was determined that repairs made after the earlier mishap were inadequate. Another weakening of supports and a leak in a pipe was blamed on a fix installed after the 2007 incident. Two bracket supports were attached to the beams where three should have been, officials said.