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No. 2 reactor at Onagawa nuclear plant in Miyagi, halted by 2011 tsunami, passes safety screening

n-onagawa-a-20200227-870x606People protest Wednesday in Tokyo over the Nuclear Regulation Authority giving its approval for the safety measures implemented at the No. 2 unit of the Onagawa nuclear power plant in Miyagi Prefecture. 

February 26, 2020

A nuclear reactor in Miyagi Prefecture damaged by the 2011 earthquake and tsunami disaster formally cleared screening by a national nuclear watchdog on Wednesday, paving the way for it to restart after anti-disaster measures are completed by the end of March next year.

The No. 2 unit of Tohoku Electric Power Co.’s Onagawa plant won the approval of the Nuclear Regulation Authority, becoming the second disaster-damaged reactor, after the Tokai No. 2 power plant in Ibaraki Prefecture, to pass stricter safety standards introduced after the Fukushima nuclear crisis.

Construction of an 800-meter seawall is among anti-disaster measures that still need to be completed at the plant, which straddles the town of Onagawa and the city of Ishinomaki. The operator also needs to obtain consent from local residents before it can restart the plant.

On March 11, 2011, all three reactors at the Onagawa complex shut down when a massive earthquake rocked northeastern Japan and a 13-meter tsunami hit the area, flooding the underground floors of the No. 2 unit.

However, the facility’s emergency cooling system operated correctly and there was no meltdown of the type that occurred at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 plant.

Tohoku Electric applied for safety screening for the No. 2 unit in December 2013 and has been constructing the seawall that will top out at 29 meters above sea level. It expects to spend about ¥340 billion ($3.08 billion) in total on the anti-disaster measures.

The company has already decided to scrap the No. 1 reactor, which began operations in 1984, and is considering applying for the restart of the No. 3 unit, which started power generation in 2002.

When it restarts, the Onagawa No. 2 reactor, which began commercial operations in 1995, will be the first boiling water reactor — the same type used at the Fukushima No. 1 plant — to resume operations since the 2011 earthquake and tsunami hit. The disaster claimed nearly 16,000 lives and left more than 2,500 missing.

Other boiling water reactors at Tepco’s Kashiwazaki-Kariwa plant in Niigata Prefecture and the Tokai No. 2 plant of Japan Atomic Power Co. have already secured approval to resume operations from the regulator, but have yet to obtain local consent.

https://www.japantimes.co.jp/news/2020/02/26/national/miyagi-nuclear-reactor-safety/#.Xlare0pCeUk

February 27, 2020 Posted by | Japan | , | Leave a comment

Tohoku reactor restart: What is the state of Japan’s nuclear policy?

Their contempt for the Japanese’ public’s will and the health and well being of people, animals, plants, oceans, rivers, lakes, genetic pools and the economies of the northern hemisphere is appalling. Abe, LDP, nuke industry, anyone that’s pro-nuke.’

n-nuclear-a-20191210-870x666Members of the government’s expert panel inspect Tohoku Electric Power Co.’s Onagawa nuclear power plant in Miyagi Prefecture in April.

Dec 9, 2019

OSAKA – In late November, the Nuclear Regulation Authority (NRA) gave the green light for restarting the No. 2 reactor at Tohoku Electric Power Co.’s Onagawa plant in Miyagi Prefecture, which had been damaged in the March 11, 2011, earthquake and tsunami. The announcement once again put the spotlight on the country’s nuclear power policy, not only in Tohoku but nationwide.

Why did the Onagawa restart attract so much attention?

While the Onagawa plant is actually the second damaged on 3/11, after the Tokai No. 2 power station in Ibaraki Prefecture, to pass the NRA’s new safety regulations for nuclear power plants prepared after the disaster, it happens to be the nuclear plant closest to the epicenter of the magnitude 9 quake that struck off the Tohoku coast that day.

The Onagawa facility is located near Ishinomaki, which received extensive damage and much domestic and international media attention after the tsunami claimed the lives of 74 Okawa Elementary School students.

In addition, the Onagawa reactor, which was flooded on 3/11, is the first boiling water reactor to have its restart application approved by the NRA.

There are three kinds of nuclear reactors in operation in Japan: 14 pressured water reactors (PWRs), four advanced boiling water reactors (ABWRs) and 13 boiling water reactors (BWRs), which are the same kind as those at the Fukushima No. 1 plant destroyed by the 3/11 quake and tsunami. The PWRs are considered more technologically stable than the other kinds, and have a better ability to contain radiation.

Now that the NRA has greenlighted Onagawa’s restart, does that mean it will happen anytime soon?

That depends on a number of factors. The Onagawa plant is not ready to be fired up tomorrow. It must first complete the installation of various anti-disaster measures, including a 29-meter-high, 800-meter-long seawall along the Pacific coast to guard against tsunami as high as 23.1 meters. That will not be completed until sometime in fiscal 2020, which begins April 1.

Furthermore, various local governments, including Ishinomaki and Miyagi Prefecture, will have to give their consent to the restart. That could involve long, drawn out negotiations between the utility and local residents and politicians. It’s also probable that lawyers and local citizens opposed to a restart will seek a court injunction to halt the move based on safety concerns. If a court approves an injunction, that will create further delays.

How many other nuclear power plants are there and what are their statuses?

As of this month, there are nine reactors officially in operation. Four belong to Kansai Electric Power Co. (Kepco), which provides electricity mainly to Kyoto, Osaka, Nara, Hyogo, Shiga and Wakayama prefectures. Another four belong to Kyushu Electric Power Co. One of Shikoku Electric Power Co.’s reactors at its Ikata plant is also operating.

Another six reactors have made improvements to meet the new, post-3/11 quake safety standards and have received NRA approval to restart. These include two reactors at Tokyo Electric Power Company Holdings’ Kashiwazaki-Kariwa plant in Niigata Prefecture, two of the four reactors at Kepco’s Takahama plant (the other two are in operation) in Fukui Prefecture, one reactor at Kepco’s Mihama plant (the other two have been decommissioned), also in Fukui Prefecture, and one reactor at Japan Atomic Power Co.’s Tokai No. 2 plant in Ibaraki Prefecture. The other reactor at the facility has been decommissioned.

Nearly a dozen reactors are now in the process of undergoing safety reviews and will have to upgrade their facilities to meet tougher NRA standards for disaster preparedness, and then, if they receive approval to restart, will go through the process of obtaining local consent.

These include reactors in Hokkaido, Aomori, Shizuoka, Ishikawa, Fukui and Shimane prefectures.

Finally, another nine reactors have not applied to be restarted under the new regulations, and 24 reactors, including all six Fukushima No. 1 plant reactors and all four Fukushima No. 2 plant reactors, as well as four of Kepco’s 11 reactors in Fukui Prefecture, are being decommissioned.

How much electricity does nuclear power provide?

Figures vary, sometimes greatly, depending on how many plants in operation were shut down for inspection during a particular year. The latest figures from the Ministry of Economy, Trade and Industry’s Agency for Natural Resources show that in 2017, nuclear power provided 3.1 percent of Japan’s electricity. The Institute for Sustainable Energy Policies, a nonprofit research institute, estimates that based on its own surveys of utilities, nuclear provided 4.7 percent of Japan’s electricity last year.

What about the future for nuclear power in Japan?

The government’s long-term energy policy for 2030 calls for nuclear power to make up around 20 to 22 percent of the nation’s energy mix, and it is pushing hard for the restart of as many idled reactors as possible. By then, the plan calls for renewable energy to account for 22 to 24 percent of the mix, LNG to make up 27 percent, coal 26 percent and oil 3 percent.

But the obstacles to restarting, or continuing to operate, nuclear plants in the coming years are vast. In addition to local opposition that could delay restarts for months or years, costing the utilities money, they include such issues as the economics of running reactors past 40 years, for which the utilities must first spend money to upgrade their facilities in order to meet new NRA standards regarding reactors older than four decades.

While Kepco has secured permission to operate three reactors already over 40 years old for another two decades at the most, other utilities with reactors currently more than 30 years old — such as Tepco’s Kashiwazaki-Kariwa No. 1 reactor (34 years old) — will have to decide within a few years whether it’s worth the investment of money and time to apply for a two-decade extension or whether it’s cheaper to decommission.

A second problem has to do with spent nuclear fuel generated by the restarted reactors.

Tokyo is making efforts to find local governments able and willing to have a midterm spent fuel storage facility built in their backyard, and has agreed to offer financial incentives for anyone willing to accept a facility. No luck so far. Meanwhile, in Fukui Prefecture, which has the largest concentration of reactors (13 commercial reactors plus the Monju experimental fast-breeder reactor) in the nation, Gov. Tatsuji Sugimoto is insisting that such storage facilities be built outside the prefecture. His position could lead to other prefectures hosting nuclear power plants to take a firmer stance with utilities and the central government over what to do with spent nuclear fuel when they come seeking local consent for their own restart plans.

https://www.japantimes.co.jp/news/2019/12/09/reference/japan-nuclear-power-onagawa-reactor-restart/?fbclid=IwAR2X_PkXWLrk48fGSeySC-WoU_m0aNvU52v8fOybK1_vEAGUsqmxNH-sA68#.XfHoRfxCeUm

December 17, 2019 Posted by | Japan | , | Leave a comment

Safety concerns linger although Onagawa reactor cleared to restart

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The Onagawa nuclear power plant in Miyagi Prefecture.
November 29, 2019
Tohoku Electric Power Co. announced Nov. 27 that the No.2 reactor at its Onagawa nuclear power plant in Miyagi Prefecture has cleared the regulatory screening for a restart, more than eight years after it was damaged in the earthquake and tsunami that triggered the Fukushima disaster.
The Nuclear Regulation Authority (NRA) has produced a draft report on its safety inspections of the reactor, saying it has met the new safety standards introduced after the 2011 Fukushima nuclear disaster. The NRA’s action means the unit, which is a boiling water reactor like those at the stricken Fukushima No. 1 nuclear power plant, has passed a key test for its reactivation.
The nuclear safety watchdog has spent six years assessing the safety of the reactor since the utility applied for a license to bring the unit back online.
Tohoku Electric Power has taken safety measures to ensure that the reactor will withstand an earthquake with a shaking intensity twice larger than previously assumed. The company has also promised to build a 29-meter high seawall in line with the lessons learned from the 2011 disaster, when the plant came close to being hit by the tsunami. Special facilities to respond to a severe accident will also be installed.
Despite all these new safety measures, the risk of the unexpected occurring, resulting in damage to the reactor, should not be ruled out.
There are still more things that should be done and considered before debating the appropriateness of allowing the utility to restart the reactor when the promised measures have been taken. The work is expected to be completed in fiscal 2020.
The biggest worry about the plan to bring the reactor back on stream is the lack of a viable plan for emergency evacuations of local residents.
The Oshika Peninsula, where the nuclear plant stands, has a rugged coastline that turns back upon itself repeatedly. This topographic feature limits possible emergency escape routes.
The local populations of both Onagawa and Ishinomaki, which host the plant, are aged, with people 65 years or older accounting for more than 30 percent of all the residents. One in every five local residents lives alone.
An evacuation plan based on the use of private cars and buses will be difficult to carry out. That will be all the more so in cases of complex disasters such as an earthquake and tsunami occurring in succession.
Some 210,000 people live within 30 kilometers from the nuclear plant including residents of five other neighboring municipalities. The local governments within this radius are legally required to develop evacuation plans. It will be a herculean task to secure evacuation centers that can take in all these people.
The governments of many nuclear host communities in rural areas where the local economy is heavily dependent on state subsidies and jobs provided by nuclear plants will agree to reactor restarts.
But many local residents in these communities remain deeply concerned about the safety of the reactors in their towns and cities.
Earlier this month, a group of Ishinomaki citizens filed a request with the Sendai District Court for an injunction to ban the Miyagi governor and the Ishinomaki mayor from approving the utility’s plan to restart the reactor. The legal action clearly reflects local residents’ anxiety.
A proposal to hold a local referendum on the planned reactor restart based on 110,000 signatures was submitted to the prefectural assembly although it was rejected.
The heads of some local governments in the region have expressed their opposition to the utility’s plan to resume operation of the reactor, saying they cannot take the responsibility to protect the lives of local residents during emergencies.
The Asahi Shimbun has argued that a wider scope of communities around nuclear power plants should be involved in the process. As for the Onagawa plant, there is a system to communicate the opinions of the five surrounding municipalities to Tohoku Electric Power through the prefectural government.
The Fukushima disaster has shown in a graphic manner that a wide range of areas are affected by any serious nuclear accident.
Both the Miyagi prefectural administration and Tohoku Electric Power should pay serious attention to the voices of local communities in wide areas surrounding the nuclear plant.
Nuclear power generation has been promoted under a national policy while nuclear plants have been operated by private-sector companies.
Commenting on Tohoku Electric Power’s plan to resume operating the reactor at the Onagawa plant, Miyagi Governor Yoshihiro Murai has said the central government should make the final decision and take responsibility for it.
In addition to the local administrations and utilities involved, the central government needs to address doubts and concerns among local residents related to a plan to restart a nuclear reactor.
Already, nine reactors have been reactivated under the new nuclear safety standards.
But the Onagawa plant is located in an area that has been repeatedly hit by earthquakes and tsunami. Experts say there are risks of the plant being struck by a major disaster. These facts should not be forgotten.

December 2, 2019 Posted by | Japan | , | Leave a comment

Nuclear watchdog approves restart of Onagawa reactor in Miyagi hit by 3/11 tsunami

First Japanese boiling water reactor (like Fukushima Daiichi) has just been approved for restart of operations. This is the tenth Japanese nuclear power plant to restart since all nuclear power operations were shutdown following the March 11, 2011 triple catastrophe (earthquake, tsunami and triple meltdown.)
Interesting that Japanese nuclear regulators required the restart of these boiling water reactors be predicated on the installation of filtered hardened containment vents (FHCV). The FHCV allows the operator during a severe nuclear accident to vent to the General Electric design’s vulnerable and substandard containment structure of extreme pressure, heat, explosive non-compressible hydrogen gas and while retaining the radioactivity in newly constructed high efficiency filtration system housed in a separate hardened containment. The original FHCV was proposed by US Nuclear Regulatory Commission staff in November 2012 as a requirement for the continued operation of 23 U.S. General Electric Mark I boiling water reactors and rejected by a majority vote of the Commissioners. For U.S. reactors financial margins come before public safety margins.
 
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Tohoku Electric Power Co.’s Onagawa nuclear power plant in Miyagi Prefecture is seen on Feb. 18
Nov 27, 2019
A nuclear power plant reactor that was damaged by the 2011 earthquake and tsunami disaster and idled under stricter safety standards following the Fukushima crisis won approval from the nuclear watchdog on Wednesday for operations to resume.
The No. 2 unit of Tohoku Electric Power Co.’s Onagawa plant in Miyagi Prefecture received the green light after the addition of disaster prevention measures, including a towering seawall that is nearing completion.
 
The approval, given in a unanimous vote, was the first to be secured by the operator under the revised standards. The reactor is only the second of those damaged in the March 2011 calamity to clear the Nuclear Regulation Authority’s new safety regulations, after the Tokai No. 2 power station in Ibaraki Prefecture.
Before the reactor can be restarted, the plant, which straddles the town of Onagawa and the city of Ishinomaki, still needs to finish installing anti-disaster measures, which are expected to be completed in fiscal 2020, and receive consent from the local governments.
Tohoku Electric expects to spend ¥340 billion ($3.1 billion) on the measures, the bulk of that being spent the seawall — which will run along 800 meters of Pacific coast and rise 29 meters above sea level to guard against tsunami as high as 23.1 meters. In the March 2011 disaster, parts of the basement floors of Onagawa’s No. 2 unit were flooded.
Costs for enhanced safety measures have ballooned and are expected to swell further with the construction of facilities to be used in the event of a terrorist attack, also required under the new safety standards.
The Onagawa plant is the closest nuclear plant to the epicenter of the magnitude 9.0 quake that struck northeastern Japan on March 11, 2011, and heavy shaking triggered an automatic shutdown of its three reactors.
Its No. 2 reactor building suffered flooding from the subsequent 13-meter tsunami, losing up to 70 percent of its capacity to resist earthquakes, and tremors damaged four out of five external power supplies at the plant. But the remaining line was enough to cool the reactors into a cold shutdown, unlike the situation at the Fukushima No. 1 plant run by Tokyo Electric Power Company Holdings Inc., or Tepco, where the triple meltdowns occurred.
Tohoku Electric applied for safety screening for the No. 2 reactor at the Onagawa plant in December 2013, and its restart should save the utility ¥35 billion annually in fuel costs.
The No. 1 reactor is scheduled to be decommissioned, and the utility is still considering whether to seek approval to restart the No. 3 reactor.
The Onagawa No. 2 reactor may become the first boiling water reactor — the same type used at the Fukushima No. 1 plant — to resume operations following the 2011 earthquake and tsunami disaster, which claimed nearly 16,000 lives. More than 2,500 remain missing today. In Onagawa, those killed or missing total more than 800.
Other boiling water reactors at Tepco’s Kashiwazaki-Kariwa plant in Niigata Prefecture and the Tokai No. 2 plant of Japan Atomic Power Co. have already secured NRA approval to resume operations, but have yet to obtain local consent.
Onagawa’s approval will be formalized following a roughly one-month period where the NRA will accept comments from the public. During the meeting Wednesday, NRA Commissioner Shinsuke Yamanaka said the safety of the plant’s structural design had been reviewed carefully, in consideration that the Tohoku region has been hit by big earthquakes in the past.
At Onagawa, more than 80 percent of houses were damaged following the March 2011 tsunami, and locals were divided on whether to back the restart of the plant.
“It is OK to restart if it’s safe,” said Shoichi Chubachi, 82, who still lives in public housing for people who lost their homes in the disaster. “The town has reaped benefits from the nuclear plant. I cannot say I’m opposed.”
“I think there’s sufficient electricity without nuclear power,” said housewife Chisato Uno, 69. “Taking into account our children and grandchildren, no nuclear power is better.”
A woman in her 80s who lives alone expressed concerns. “I can’t drive a car and I cannot evacuate because my legs are weak,” she said.

December 2, 2019 Posted by | Japan | , | Leave a comment

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?
Onagawa-unit-1-(Tohoku).jpg
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.

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!
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.

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

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.

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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