10月19日 アメリカ:サンオノフレ原発について地震や津波に耐えうる設計上の見直しをNRCへ、電力会社は地震調査へ
1月30日 アメリカ・イリノイ州のバイロン原発、機器故障で停止【減圧のためトリチウムが含まれる蒸気をベント】に関連しています。

Testing At Byron Nuclear Plant After Power Outage
KWQC News Updated: Jan 31, 2012 05:45 PM EST

The state of Illinois sent agents to the scene a day after a nuclear incident in northern Illinois. On Monday, officials at the Byron Nuclear Power Plant reported an "unusual event" that caused the plant to lose power.

The state says on Tuesday, agents with the Illinois Emergency Management Agency collected samples around the plant to make sure that a steam release, triggered when the reactor shut down, did not contain hazardous levels of radioactive Tritium. Officials say they do not expect to find any harmful levels, but are collecting samples will verify that.

Agents are collecting water and vegetation samples and will compare them to samples routinely taken within the past month. The samples will be taken to the agency's laboratory in Springfield for analysis. Results should be available within a few days.

Officials have been closely monitoring data on conditions at the plant since the Byron Unit 2 reactor tripped Monday morning due to a loss of off-site power. The plant is operated by Exelon Energy and according to the Associated Press, Exelon officials have traced the power failure to an electrical insulator in a switchyard. The bad insulator will be sent to a lab for analysis and officials hope to replace it by Tuesday evening. It's unclear how soon before the reactor could return to service.

The plant is located about 40 miles northwest of Sterling/Rock Falls.

Failed Insulator Triggers Loss of Offsite Power at Byron Nuclear Plant
February 1, 2012
POWERnews /Powe Businesss and Technology for the Gloal Generation Industry
A failed electrical insulator at a switchyard at Exelon Generation Co.’s two-unit Byron nuclear plant in Lisle, Ill., has been blamed for the loss of offsite power on Monday morning that automatically shut down Unit 2 and forced Exelon to declare an “Unusual Event.”

Unit 2 shut down at about 10:18 a.m. CST, and smoke was seen rising from an onsite station transformer, though emergency responders found no evidence of fire, the Nuclear Regulatory Commission (NRC) reported later on Monday. Diesel generators were immediately deployed, and steam was released from the non-nuclear side of the plant to aid in the cooling process. The Unusual Event, the lowest of the four emergency classifications as established by the NRC, was terminated at 8 p.m. on Tuesday, following return of power to Unit 2.

Exelon said teams of “technical experts” had also completed repairs to the failed insulator on Tuesday but noted that a comprehensive investigation into the failed insulator continued.

“Our diesel generators performed as expected in providing continuous electricity to the unit during the Unusual Event. Plant teams will now focus on a safe and measured approach to returning Unit 2 to the electrical grid,” said Byron Station Site Vice President Tim Tulon, though he did not elaborate on when the plant could resume operations.

The NRC on Tuesday, meanwhile, initiated a special inspection to review how plant equipment responded to the loss of offsite power and evaluate the facts and circumstances surrounding the incident. The special inspection report is expected within 45 days.

Unit 2 was reported in “safe and stable shutdown condition. “There was a steam release from the non-nuclear side of the plant with trace amounts of tritium,” the agency said. “This type of steam release is used by nuclear power plants to release pressure in order to maintain the plant in a stable condition. Doses to the public from this type of release are significantly below even the most stringent Federal protective limits and, therefore, do not pose a risk to public health and safety.”

In a related story, Southern California Edison (SCE) on Tuesday reported it had begun a “precautionary shutdown” of Unit 3 at the San Onofre Nuclear Generating Station near San Clemente, Calif., because sensors had detected “a possible leak in one of the unit’s steam generator tubes.” The leak posed no imminent danger to the public or plant workers, and no release to the atmosphere had occurred.

San Onofre Unit 2 is currently offline for a planned maintenance, refueling, and technology upgrade outage. SCE said it had “ample reserve power” to meet customer needs while Unit 3 is offline, and noted it had informed the NRC of the possible leak.

Sources: POWERnews, Exelon, NRC, SCE





米加州などで大規模停電 原発が緊急停止、500万人に影響
産経ニュース 2011.9.9 11:10

にほんブログ村 環境ブログ 原発・放射能へ

米加州原発で微量の放射能漏れか 緊急停止
2012/02/02 13:56   【共同通信】