Texas Reactor Leak Shakes
US Nuclear Industry
By Chris Baltimore

ROCKVILLE, Md (Reuters) -- Managers of a big Texas nuclear power station told U.S. Nuclear Regulatory Commission staff last week they do not know what caused a leak in the plant's reactor, a discovery that could set off safety shutdowns at dozens of other plants.
The South Texas 1 plant, 90 miles southwest of Houston, has been shut since late March when a routine inspection turned up two tiny boric acid deposits on the underside of its pressurized reactor vessel.
Boric acid, used in reactor coolant water to control its radioactivity, is highly corrosive in open air and can eat through metal.
Plant officials said the leak, which may have begun 4 years ago, poses no public health threat.
But the mysterious deposits have raised concerns about possible leaks at 68 other U.S. reactors of similar design, said Richard Barrett, director of the engineering division of NRC's reactor office.
Those reactors, more than half of the 103-unit U.S. fleet, account for about 10 percent of the nation's electricity.
"It's very possible that this would have wider industry-wide implications," Barrett said during a public briefing by South Texas 1 plant managers.
Senior NRC staff planned to meet later last week to discuss the problem in more detail, Barrett said.
Managers of the South Texas Project Nuclear Operating Co., which runs the plant's two reactors on behalf of its four owners, told the NRC they will disassemble the plant's reactor to find the "root cause" of the leak.
"I think we have more questions than answers at this juncture," said Steve Thomas, one of the plant's managers.
One possible explanation is that a small, intermittent leak developed around insulated tubes that pierce the reactor's metal hull to allow instruments to measure its inner workings, Thomas said. A prior inspection on the reactor in November found no problems.
Plant operators said the boric acid deposits, smaller than an aspirin tablet, could be the result of a leak of up to 700 liters of coolant from the reactor over as much as four years.
The NRC ordered owners of all U.S. pressurized water reactors, like the South Texas unit, to inspect their reactor vessel heads after finding severe corrosion last year at FirstEnergy Corp.'s (FE.N) Davis-Besse unit in Ohio, where leaking boric acid ate a cantaloupe-sized hole in that reactor's outer hull.
Since then, several U.S. utilities including FirstEnergy have spent millions of dollars to replace faulty reactors.
Prior to the South Texas plant inspection, leaks at the bottom of reactor vessels had not been a concern.
The 1,250 megawatt Texas plant, which generates enough power to supply more than a million homes, was shut in late March for routine refueling, a job that typically takes about 35 days. But repairs could keep the giant facility shut until late summer, months longer than expected.
Nuclear watchdog groups were skeptical that the operator can complete repairs on its current schedule.
"They don't have a clue what caused it, which means that their schedule is overly optimistic," said Jim Riccio at Greenpeace.
The NRC must approve any repair plans and will ultimately decide when the unit is ready to return to service.
The facility is jointly owned by units of CenterPoint Energy Inc. (CNP.N) and American Electric Power Co. (AEP.N), and the municipal utilities of San Antonio and Austin, Texas.



This Site Served by TheHostPros