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TEPCO submits decommissioning plan for Onagawa 1

Another Japanese boiling water reactor calls its quits and moves to decommission. This the fifth Japanese boiling water reactor in a week pulled from even having hope of restart along with Fukushima Daini 1 through 4. Who says “operating experience” isn’t shrinking for boiling water reactors in USA and around the world?
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02 August 2019
Tohoku Electric Power Company has applied to Japan’s Nuclear Regulation Authority (NRA) for approval of its decommissioning plan for unit 1 of the Onagawa nuclear power plant in Miyagi Prefecture. The company announced in October 2018 its decision to scrap the unit as it said required safety upgrades would be too expensive and time-consuming.
Unit 1 of the 524 MWe boiling water reactor (BWR) that began operations in 1984 is of a different design to the other two larger (825 MWe) BWR units there, which began operating in 1995 and 2002, respectively. Tohoku also operates a single 1100 MWe BWR at its Higashidori plant in Aomori Prefecture, which started operation in late 2005. Tohoku plans to restart units 2 and 3 at the Onagawa plant, as well as its Higashidori plant.
Last October, Tohoku said a problem unique to Onagawa 1 is the restricted space within its containment vessel in which to install additional safety equipment, such as fire extinguishing equipment, power supply equipment and alternative water injection pumps. It decided to decommission the unit after taking into account its generating capacity and the number of years it would be able to operate if it were restarted. Onagawa 1 became the tenth operable Japanese reactor to be declared for decommissioning since the March 2011 Fukushima Daiichi accident.
Its decommissioning plan for the unit, which it submitted  to the NRA on 29 July, outlines the facilities and equipment to be dismantled and a timetable for completing the work. Decommissioning will take about 34 years and will be carried out in four stages. The first stage, lasting about eight years, will involve preparing the reactor for dismantling (including the removal of all fuel and surveying radioactive contamination), while the second, lasting seven years, will be to dismantle peripheral equipment from the reactor and other major equipment. The third stage, taking about nine years, will involve the demolition of the reactor itself, while the fourth stage, taking about ten years, will see the demolition of all remaining buildings and the release of land for other uses.
During the first stage, all fuel is to be removed from the operation of Onagawa 1. This includes 821 used fuel assemblies stored in unit 1’s storage pool, which will be transferred to unit 3’s storage pool. These assemblies will later be transported for reprocessing, together with 95 used fuel assemblies from unit 1 currently stored at unit 2 and 66 stored at unit 3. There are also 41 unused fuel assemblies stored at unit 1.
A total 60 tonnes of high-level radioactive waste is expected to be generated through the decommissioning of Onagawa 1, together with 740 tonnes of low-level waste and 5340 tonnes of very low-level waste. A further 12,400 tonnes of non-radioactive waste will also be generated through the clearance of the site.
Tohoku said it expects the decommissioning of the unit to cost a total of JPY41.9 billion (USD392 million), with dismantling activities costing JPY30.0 billion and waste disposal accounting for the remainder.
In March 2015, the Ministry of Economy, Trade and Industry’s Agency for Natural Resources and Energy revised the accounting provisions in the Electricity Business Act, whereby electric power companies can now calculate decommissioning costs in instalments of up to 10 years, instead of one-time as previously. This enhanced cost recovery provision was to encourage the decommissioning of older and smaller units.
The Onagawa plant is on Japan’s northeastern coast and was the closest plant to the epicentre of the earthquake and tsunami of 11 March 2011. Although the earthquake knocked out four of the five external power lines, the remaining line provided sufficient power for the plant’s three reactors to be brought to cold shutdown. Onagawa 1 briefly suffered a fire in the non-nuclear turbine building. A mission from the International Atomic Energy Agency in August 2012 concluded the plant had been largely unaffected by the tsunami as it sits on an elevated embankment more than 14 metres above sea level.
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August 3, 2019 Posted by | Japan | , | Leave a comment

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!
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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.

October 27, 2018 Posted by | Japan | , , | Leave a comment

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

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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

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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.

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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