Wednesday, February 1, 2012

LA Times: Small leak at San Onofre nuclear power plant investigated

So there was a leak at San Onofre, not just a possibility of a leak.

LA Times (2/1/2012):

Southern California -- this just in

Small leak at San Onofre nuclear power plant investigated
February 1, 2012 | 7:15 am

Southern California Edison officials continued their investigation Wednesday of a small water leak in one of two units at the San Onofre nuclear power plant.

The unit was shut down at 5:30 p.m. Tuesday after a sensor detected a leak in a steam generator tube; an assessment of the leak will determine its cause.

The shutdown was ordered out of precaution, Southern California Edison spokesman Gil Alexander said.

He said the incident was so minor "it wouldn't even qualify as the least severe" infraction under Nuclear Regulatory Commission guidelines.

The leak posed no risk to workers and did not require an evacuation, Alexander said.

The unit has a generating capacity of 1,100 megawatts power and is able to meet the needs of 700,000 Southern California homes.

The shutdown is not expected to affect customer's power supply.


Professional, Innovative, Dependable said...

Was it mentioned previously that there is a crack inside the generator wall through which the fluid leaked?

That these are replacement generators, which had problems from when they were new with cracks in the walls at the sites of welds?

Also, the water was contaminated. At least one of the loops contained radioactive water.

Now they are saying "80 to 100" gallons of water a day.


An official with the Nuclear Regulatory Commission said Wednesday that a water leak this week at the San Onofre Nuclear Generating Station could have released a small amount of radiation into the atmosphere, contradicting an earlier statement by plant owner Southern California Edison.
Victor Dricks, a spokesman for the NRC, said a small release could have occurred because the leaking component at San Onofre's Unit 3 reactor vents into a building outside the reactor's towering containment dome. That building is not sealed or pressurized, he said....
Whether the gas got out of the unsealed building is not known....
...In a news release, the company said it believes at least one of the 9,727 thin tubes inside the generator burst, allowing radioactive reactor coolant to mix with nonradioactive water used to make the steam that generates power at the plant.
However, on Wednesday Edison appeared to retreat from its initial statement Tuesday evening declaring that no amount of radioaction had been released into the atmosphere....
...Neither the NRC nor Edison were able to supply the amount of radiation detected in the auxiliary building. The NRC is continuing to investigate Edison's response to the incident....
.....Alexander also said Wednesday that radioactive water was passing through a crack inside the generator at a rate of 80 to 100 gallons per day when Edison began shutdown procedures.
He said engineers spent Wednesday drawing up plans on how they would pinpoint the leak while they waited for the reactor to cool enough to enter the Unit 3 containment dome.
Until engineers can enter the Unit 3 structure and begin probing each individual tube, they won't know how extensive the damage is, officials said....
....The leak is not Edison's first problem with the new steam generators.
In September 2009, Edison met with NRC officials to discuss weld defects that were detected in both of the 640-ton crucibles.
The utility notified the NRC in August 2009 that the replacement generators for Unit 3 had developed cracks in a weld that connects a 5-inch-thick steel plate that supports each generator's innards.
Inspections found that use of a special metal-gouging tool caused the welds to become brittle and crack. Mitsubishi Heavy Industry, the company that built the generators for Edison, fixed the cracked welds, and they passed NRC inspection.
It was not known Wednesday whether the leak occurred in that area.
Some groups have recently criticized the way Edison has handled releasing information regarding problems.
In November, nuclear watchdog and environmental groups criticized plant operators for taking more than an hour to notify the public of an ammonia leak in a storage tank that prompted the evacuation of some workers. There was no danger to the public, the company said at the time.
Daniel Hirsch, who lectures on nuclear policy at UC Santa Cruz, said he was concerned that this week's water leak occurred with recently installed equipment.
"Edison has historically not been candid about the problems at San Onofre. That lack of transparency causes tremendous distrust and increases risk," Hirsch said.
"It makes one wonder about the quality assurance for the replacement equipment," he added. "This is not due to old equipment breaking, but new equipment that wasn't up to snuff in the first place."....


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