Southern California breaking news and trends

San Onofre can't take the pressure, tubes fail test

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It does not take a nuclear physicist to understand the troubling situation at the San Onofre Nuclear Generating Station. 

Three tubes failed to pass a pressure test this week, prompting the U.S. Nuclear Regulatory Commission (NRC) to send an inspection team to San Diego County.

The tubes, which move radioactive water through a steam generator, have been under scrutiny after unusual deterioration was found following a small radioactive gas leak in January. 

NRC officials explained the relatively obvious in a statement, by noting that the tubes that failed are more likely to rupture during plant events affecting pressure in the generator. 

It goes on to say that tube integrity is important because "the tubes provide an added barrier inside the containment building to prevent a radioactive steam release."

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NRC requiring modifications to every U.S. nuclear power plant

san onofre nuclear power plant atomic

Jason Hickey/Flickr Creative Commons

U.S. nuclear power plants have until the end of 2016 to comply with new safety recommendations released Friday by the Nuclear Regulatory Commission. 

Plants were ordered to begin immediately implementing the upgrades in an effort to prevent a large-scale radioactive crisis like what occurred last year at Japan's Fukushima Daiichi nuclear power plant following the earthquake and tsunami.

Recommendations were laid out in a three-part plan. Two points apply to every U.S. commercial nuclear power plant, including those under construction and recently licensed new Vogtle reactors. One point only concerns a specific type of containment structure, said the NRC in a press release.

  • The first Order requires the plants to better protect safety equipment installed after the 9/11 terrorist attacks and to obtain sufficient equipment to support all reactors at a given site simultaneously.
  • The second Order requires the plants to install enhanced equipment for monitoring water levels in each plant’s spent fuel pool.
  • The third Order applies only to U.S. boiling-water reactors that have “Mark I” or “Mark II” containment structures. These reactors must improve venting systems (or for the Mark II plants, install new systems) that help prevent or mitigate core damage in the event of a serious accident.

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San Onofre reactor still down one week later

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One week after a radiation leak prompted a shut down at San Onofre, the nuclear plant's Unit 3 reactor remains offline. 

The reactor was finally cool enough on Monday for workers to install inspection equipment, but it was unclear how long the unit would remain out of service, according to plant operator Southern California Edison and officials at the Nuclear Regulatory Commission, reports U-T San Diego

During an inspection, unusual wear was found on hundreds of steam generator tubes pumping radioactive water in Unit 2, however that reactor is still in service. The NRC said tubes showed excessive wear. Edison called the findings preliminary.

Over the past two years, generators in both reactors were replaced with $670 million worth of new equipment manufactured in Japan by Mitsubishi Heavy Industries.

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San Onofre worker falls into reactor pool at nuclear plant

san onofre nuclear power plant atomic

Jason Hickey/Flickr Creative Commons

A veteran worker lost his balance at the San Onofre nuclear plant last week and fell into the Unit 2 reactor pool while trying to retrieve a flashlight. The pool, more than 20 feet deep, contains water that continually circulates through the reactor core.

The worker did not suffer significant radiation exposure in the incident, and was "wearing all of the appropriate safety equipment, including a life preserver vest," said Southern California Edison spokesman Gil Alexander told the L.A. Times.

Highly radioactive uranium fuel normally sits at the bottom of the pool, but it had been removed by workers, according to officials. Stray fuel particles may have been floating in the water and could have been swallowed. They would have been the most likely source of radiation, said Nuclear Regulatory Commission spokesman Victor Dricks.

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Tubes pumping radioactive water are showing 'unusual' wear at San Onofre

David McNew/Getty Images

San Onofre Nuclear Generating Station

Tubes inside a new steam generator at San Onofre Nuclear Generating Station are showing unusual and potentially dangerous signs of deterioration, federal regulators announced on Thursday.

"The amount of wear that we are seeing on these tubes is unusual for a new steam generator," said Nuclear Regulatory Commission spokesman Victor Dricks. 

More than 800 tubes of the San Diego County plant showed a 10 percent thinning in the tube wall, officials said. 69 others had at least 20 percent thinning. And two tubes needed to be plugged and taken out of service because a third of the wall was worn away.

"If you have that kind of thinning anywhere along the length of the tube, you have a problem because it degrades the integrity of the tube, which can contribute to leaks," explained Dricks.

Safety implications could be "very severe," warned Joram Hopenfeld, a retired NRC engineer and researcher, as the tubes are one of the primary barriers to radioactivity

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