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TEPCO to scrap Onagawa NPP’s reactor#1

The 3 reactors at the plant in northeastern Japan have been offline since the March 2011 earthquake and tsunami, and they ain’t comin’ back!
onagawa npp, miyagi pref
Tohoku Electric Power Co.’s Onagawa Nuclear Power Station is seen from a Mainichi Shimbun helicopter in Onagawa, Miyagi Prefecture, on March 11, 2011.

Utility plans to scrap reactor at Onagawa plant

October 25, 2018
Tohoku Electric Power Company has told Miyagi Prefecture that it is going to decommission an aging reactor at its Onagawa nuclear power plant.
 
The 3 reactors at the plant in northeastern Japan have been offline since the March 2011 earthquake and tsunami.
 
The utility’s president, Hiroya Harada, conveyed its decision to Miyagi Governor Yoshihiro Murai on Thursday.
 
Harada explained that additional safety steps would create technical difficulties as the No.1 reactor is more than 30 years old. The measures are required under government regulations that were introduced after the 2011 disaster.
 
Murai asked Tohoku Electric Power to put top priority on safety in scrapping the reactor as the work is expected to take a long time. The governor also asked the utility to properly disclose information and maintain stable power supplies.
 
The utility hopes to put the 2 other reactors back into operation. The No.2 reactor is being checked by the nuclear regulator, and the firm is preparing to apply for an inspection of the No.3 reactor.
 
Utilities have decided to decommission 10 reactors at 7 plants, including Onagawa, since the 2011 disaster at the Fukushima Daiichi plant. They cite the huge cost of additional safety measures. These figures do not include the all 6 reactors at Fukushima Daiichi.
 
 

Tohoku Electric to scrap aging No. 1 unit at Onagawa nuclear plant

October 25, 2018
SENDAI (Kyodo) — Tohoku Electric Power Co. said Thursday it will scrap the idled No. 1 unit at its Onagawa nuclear power plant in the northeastern Japan prefecture of Miyagi, more than 30 years after it began operation.
The company cited difficulties in taking additional safety measures as well as the relatively small output of the reactor that would make the business unprofitable. Tohoku Electric President Hiroya Harada conveyed its decision to Miyagi Gov. Yoshihiro Murai.
“We decided to decommission (the reactor) at a board meeting today. We took into consideration technical restrictions associated with additional safety measures, output and the years in use,” Harada said when the men met at the prefectural government office.
For its resumption, the company has been required to expand safety measures at the unit under stricter standards introduced after the 2011 Fukushima nuclear disaster.
Under the standards, Japanese nuclear reactors are not allowed, in principle, to operate for more than 40 years.
Having entered into operation in June 1984, the boiling water reactor with an output of 524,000 kilowatts is the oldest among four units operated by the utility.
The utility said in a statement that the No. 1 unit lacked additional space to set up fire extinguishing equipment and infrastructure to secure power supply.
Harada told a press conference on Sept. 27 that decommissioning was an option as the unit’s age made it difficult to implement the required safety measures.
In the March 2011 earthquake and tsunami disaster, the basement floors of the Onagawa plant’s No. 2 unit were flooded. The company is building a 29-meter sea wall to guard the complex.
Tohoku Electric aims to resume operations of the No. 2 unit at the three-reactor Onagawa plant in fiscal 2020 at the earliest, and the Nuclear Regulation Authority, the country’s nuclear watchdog, has been screening its safety measures.
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October 27, 2018 Posted by | Japan | , , | Leave a comment

1,130 cracks, 70% rigidity lost at Onagawa reactor building

onagawa npp.jpg

Tohoku Electric Power Co.’s Onagawa nuclear power plant straddling Miyagi Prefecture’s Onagawa and Ishinomaki

Plans to resume operations at the Onagawa nuclear power plant’s No. 2 reactor have taken a hit, as the building sustained 1,130 cracks in the walls and lost an estimated 70 percent of structural rigidity in the massive 2011 earthquake.

Tohoku Electric Power Co. revealed the extent of the damage at a Nuclear Regulation Authority review meeting on Jan. 17 to investigate plans to bring the power station in Miyagi Prefecture back online.

Tohoku Electric plans to extensively reinforce the damaged No. 2 reactor building. It is seeking to bolster the quake-resistance of the reactor to pass the stricter safety regulations on nuclear plants instituted by the NRA in the aftermath of the Fukushima nuclear crisis, triggered by the disaster.

However, that may be a long way off, as the nuclear watchdog said that it must inspect the cracks and the plans before the utility can proceed with the reinforcement project.

As with all nuclear power stations in the nation, the facility, which straddles the town of Onagawa and Ishinomaki city, went offline after the Great East Japan Earthquake and tsunami sparked the nuclear disaster.

A tremor of 607 Gals was recorded at the No. 2 reactor building when the magnitude-9.0 earthquake struck, but the structure was only built to withstand jolts of up to 594 Gals, according to Tohoku Electric. (Gal is a unit of acceleration used to describe how violently something shakes.)

A later architectural investigation found a total of 1,130 cracks on its walls, with 734 of them found on the top third-floor section. There were more cracks in the upper levels of the building as that part swayed the most during the earthquake.

The difference in the ways the uppermost section rocked compared to the lower portion when hit by aftershocks suggested that the structural rigidity of the third floor was down to 30 percent of what it was when the reactor began operating in 1995, according to the utility.

The lower section of the building, which covers two above-ground floors and three basement levels, was estimated to have lost 25 percent of its structural rigidity.

Structural rigidity assesses a building’s ability to withstand earthquakes and other stresses from outside without being distorted.

http://www.asahi.com/ajw/articles/AJ201701180054.html

 

January 18, 2017 Posted by | Japan | | Leave a comment

Radioactive water splashes Japan reactor workers; no injuries, no contamination. So they say as usual

Tsuruga.jpg

Japan Atomic Power Co said on Wednesday water used for cooling its Tsuruga No.2 reactor, shut for maintenance, splashed on 10 employees at work inside an auxiliary plant building without causing injuries or radioactive contamination.

The electricity wholesaler said about 160 liters of water spilled, splashing the workwear of staff conducting inspections on Wednesday. The company said there was no leak of radiation to the surrounding environment.

onagawa npp.jpg

The incident was reported two days after utility Tohoku Electric Power Co said about 12.5 tonnes of seawater used for cooling pumps and motors inside its Onagawa No.1 reactor building had leaked. The Onagawa reactor is also shut for maintenance.

The utility said in a statement the seawater contained no radioactive material and had not leaked to the outside environment.

http://www.reuters.com/article/us-japan-nuclear-water-idUSKBN13P0TS

December 1, 2016 Posted by | Japan | , , | Leave a comment