- 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.
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- 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.
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- Boric acid, used in reactor coolant water to control
its radioactivity, is highly corrosive in open air and can eat through
metal.
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- Plant officials said the leak, which may have begun 4
years ago, poses no public health threat.
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- 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.
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- Those reactors, more than half of the 103-unit U.S. fleet,
account for about 10 percent of the nation's electricity.
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- "It's very possible that this would have wider industry-wide
implications," Barrett said during a public briefing by South Texas
1 plant managers.
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- NEXT STEPS
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- Senior NRC staff planned to meet later last week to discuss
the problem in more detail, Barrett said.
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- 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.
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- "I think we have more questions than answers at
this juncture," said Steve Thomas, one of the plant's managers.
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- 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.
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- 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.
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- 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.
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- Since then, several U.S. utilities including FirstEnergy
have spent millions of dollars to replace faulty reactors.
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- NEW WRINKLE
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- Prior to the South Texas plant inspection, leaks at the
bottom of reactor vessels had not been a concern.
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- 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.
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- Nuclear watchdog groups were skeptical that the operator
can complete repairs on its current schedule.
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- "They don't have a clue what caused it, which means
that their schedule is overly optimistic," said Jim Riccio at Greenpeace.
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- The NRC must approve any repair plans and will ultimately
decide when the unit is ready to return to service.
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- 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.
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