弁財天

ゴフマン「専門家を信じるのではなく、自分自身で考えて判断せよ」

AP1000のポンコツ性を指摘して委員長をおろされた update2

AP1000の格納容器の耐震テストで部品が壊れた報告をNRCは見逃した。 2011年5月NYT報道。7月にヤツコ委員長は辞任することになった。格納容器建屋は特定の震度で未テストであると表明。 NRCの5人のメンバーでAP1000の耐震テスト未実施に抗議して認可に反対したのはグレゴリー・ヤツコひとりだけだった。

憂慮する科学者集団のエドウィン・ライマン 「AP1000が現在の原発より安全性が増したとは言えない。実際安全性が低下したかもしれない。設計時に想定した障害イベントにだけ対応できるだけだ。」 「フクシマは10日間電源喪失した。AP1000は72時間しかもたない。72時間後には事故が発生する。」

Fukushima inspires safety features for Georgia nuclear reactors

Fukushima inspires safety features for Georgia nuclear reactors

By Martin Rand III, CNN
December 3, 2012 -- Updated 1447 GMT (2247 HKT)
STORY HIGHLIGHTS
  • The two new nuclear reactors are the first to be approved by the NRC since 1978
  • NRC group focuses on implementing regulations based on lessons learned at Fukushima
  • Critics say natural gas is cheaper; so why use nuclear energy?
  • Because of the events at Fukushima, other countries have stopped using nuclear energy.

(CNN) -- People like to say history repeats itself, but Southern Co., which is building the first U.S. nuclear reactors approved in decades, is hoping this isn't true.

With last year's tsunami-induced disaster at the Fukushima Daichi plant in Japan, Southern doesn't want its reactors to meet the same fate.

"We learned a lot from Fukushima, and all that has been taken into account," said Cheri Collins, general manager of Atlanta-based utility, one of the largest electricity distributors in the United States. "Our uncompromising focus is safety and quality."

During October's annual France-Atlanta 2012 conference, Collins explained how the newly designed Westinghouse AP1000 nuclear reactors at Plant Vogtle in Waynesboro, Georgia, will feature safety measures meant to prevent a Fukushima sequel.

They include the reactors' not needing electrical power to shut down safely and relying less on pumps and valves and more on natural heat.

Also, because of digital operation, a human controller won't be required for 72 hours, and the main core will remain cool because of a containment cooling system.

These design changes, Collins said, are meant to protect employees and the surrounding community in the event of a natural disaster.

Collins noted that while Southern keeps safety atop its list of priorities, it can't "control the weather," and it's hard to prepare for natural disasters such as the 2011 earthquake and tsunami in Japan or 2005's Hurricane Katrina on the Gulf Coast.

According to Mike Altizer, Southern's nuclear engineering programs manager, tests involving floods, earthquakes, fires and tsunamis were conducted in hopes of ensuring a natural disaster wouldn't affect the reactors.

Yet while Southern moves forward, last year's disaster has soured the prospects for nuclear energy in some European nations, while critics ask why more isn't being done to tap safer energy such as natural gas.

On March 11, 2011, a 9.0-magnitude earthquake, the fourth-largest on record, struck off the coast of Tohoku, Japan. It triggered a tsunami with 30-foot waves that later forced the shutdown of eight reactors at two plants in Fukushima.

The next day, a nuclear emergency was declared at the Daichi and Daini plants after the tsunami cut off electricity and disabled the backup generators at the former while causing the cooling systems to fail at the latter.

Roger Hannah, a Nuclear Regulatory Commission spokesman, said the agency is taking a number of actions in response to Fukushima. They involve equipment, training, procedures, maintenance and fire protection, he said.

"The Vogtle reactors are an advanced design that has more passive safety features," Hannah said. "The NRC does not allow a plant to operate if it does not meet the agency's stringent safety regulations."

According to the NRC website, on March 12, the commission passed regulatory requirements for nuclear plants in response to Fukushima. Those requirements include mitigation strategies to respond to extreme natural events that result in a loss of power at the plant, steps to ensure the safety and reliability of venting systems designed to release pressure and the enhancement of spent fuel pools.

Also, the NRC created the Japan Lessons Learned Project Directorate, a group that focuses exclusively on implementing regulations based on the lessons learned at Fukushima.

Edwin Lyman, a senior scientist for the watchdog Union of Concerned Scientists, isn't for or against the new reactors, he said, but he expressed concerns with the tests and safety features.

"In my judgment, the AP1000 design does not have any safety advantages compared to currently operating reactors and, in fact, may be less safe," Lyman said. "The features described are only designed to function in the event of [a] so-called 'design basis accident' -- not the type of severe accident that occurred at Fukushima."

At Fukushima, there was a total loss of power for nearly 10 days, so even if the reactors had been AP1000s, they would have run into trouble after 72 hours, Lyman said. In addition, the NRC has exempted the AP1000 from some of the modifications it is requiring at operating nuclear reactors after Fukushima, he added.

He said he isn't familiar with the NRC natural disaster tests, but "certain components of the AP1000 shield building were tested for their structural integrity under certain stress conditions and actually failed the tests, but the NRC discounted the results because it claimed that those components didn't need to pass those tests."

In a May 2011 New York Times report, NRC Chairman Gregory B. Jaczko said the shield building's design numbers seemed off. Jaczko, who stepped down as chairman in July, said the company had not tested the buildings under enough possible seismic activity situations.

However, the five-member NRC voted in favor of the licenses four to one, with Jaczko being the lone vote against it. Jaczko said he wouldn't speak on record to CNN, but he told CNNMoney on February 9 that the new licenses don't go far enough in requiring the builders to incorporate lessons learned from Fukushima.

Hannah explained there were many versions of the AP1000 design that raised questions among critics during its creation. The shield building was a major area of concern but was fixed before the final design was approved, he said.

A total of 19 changes have been submitted since the design began in 2002, the last of which came in June 2011, according to the NRC website.

Asked about Lyman's assertion that the Vogtle plants would incur problems if they went 10 days without power, as did the reactors at Fukushima, Hannah said all plants have some sort of backup generator that allows power to be generated in an emergency -- even one as big Fukushima.

"We have a task force specifically designed to find out what kind of backup generators will work best in these situations," he said.

Along with the safety concerns, critics have other questions about the reactors.

For one: Why build new reactors when there are cheaper energy sources, namely natural gas?

Lyman is one of those critics, and he points to the $14 billion price tag for the two reactors, which some estimates indicate may be $1 billion short of the actual cost.

"The enormous price tag of new nuclear power projects, such as Vogtle 3 and 4, means that nuclear power is not cost-effective, especially given the low price of natural gas," Lyman said.

According to the Energy Information Administration website, new low-cost drilling technologies, growing production and an increase in reserves have made natural gas a primary source for energy, rivaling coal for the first time in April.

Before the U.S. approved plans for 13 nuclear reactors this year, the last nuclear reactor was built in 1990.

Collins downplayed the natural gas argument during the France-Atlanta conference.

While it is "the right choice of energy in terms of cost" right now, she said it has been volatile lately and that using nuclear energy is a better option as a long-lasting energy source.

The EIA states that prices for 1,000 cubic feet of natural gas, a standard measure, have fluctuated greatly of late, from $9.84 in December 2011 to $15.94 in August.

Plant Vogtle has had two nuclear reactors in operation since 1989. Unit 3 is scheduled to be in operation by 2016, and Unit 4 is scheduled to be operational a year later.

Vogtle's were the first reactors to be approved since 1978, the year before America witnessed its most serious nuclear plant meltdown.

On March 28, 1979, a unit at the Three Mile Island nuclear power plant experienced a combination of equipment malfunctions, design-related problems and worker errors that led to a partial meltdown of the unit's reactor core. It took nearly 15 years to clean up the damage.

Though no deaths or injuries occurred to plant workers or people in the nearby community of Middletown, Pennsylvania, the Three Mile accident brought about numerous safety changes in the nuclear plant industry that still resonate today.

Likewise, other countries haven't taken the events at Fukushima lightly either, and much like Three Mile Island gave the world pause in its nuclear ambitions, Fukushima is prompting changes around the globe.

For instance, Belgium and Germany have decided to get out of nuclear power entirely. Italy had been planning to start using nuclear power but decided not to, said European Commission spokeswoman Marlene Holzer.

"We have conducted a reassessment of all existing nuclear reactors in the EU in the light of Fukushima. We hope that the results and the recommendations made will be included when building new reactors," Holzer said. "Building on these results, we will come out with a new EU law on nuclear safety."

中国、新規原発の炉型を「AP1000」に一本化

  中国の今後の原子力発電開発の拠り所となる国家規画(計画)の1つである「原子力安全・放射性汚染防止『第12次5ヵ年』規画及び2020年長期目標」(原子力安全規画)が中国版ストレステスト報告である「全国民生用原子力施設の総合安全検査に関する状況報告」と同時に公表されたが、「原子力発電中長期発展規画」の改定版と「原子力発電安全規画」は本稿執筆時点(7月末)ではまだ公表されていない。

  しかし、原子力安全規画と、国務院が7月20日に公表した「『第12次5ヵ年』国家戦略性新興産業発展規画」の内容から判断すると、中国政府は新規に着工する原子力発電所で採用する炉型を「AP1000」に一本化したようだ。

  原子力安全規画では、原子力発電所に対する具体的な安全要求を提示している。それによると、新たに建設される原子力発電所については、比較的完全なシビアアクシデント予防・緩和措置を施すとしたうえで、炉心損傷確率を炉年あたり10万分の1(10-5)より低くすると同時に、大量の放射性物質が放出される事象の確率を炉年あたり100万分の1(10-6)より低くするとの目標を示した。

  国務院研究室総合司の範必副司長は、すでに着工した4基の「AP1000」型炉と2基の「EPR」を除き、中国で運転中あるいは建設中の原子力発電所が2つの要求をクリアーしていないことを明らかにした。

  2つの目標は、今回の原子力安全規画ではじめて提示されたものではない。規制当局である国家核安全局が2002年に公表した「新たに建設される原子力発電所の設計にあたってのいくつかの重要な安全問題技術政策」では、重大な炉心損傷確率を10-5より小さくするとともに、サイト外で早期に対応する必要がある大量の放射性物質が放出される事象の確率を炉年あたり10-6より小さくするとの目標が示されていた。

  また同局が2006年に公表した「原子動力プラント安全評価・験証」では、現有の原子動力プラントの炉心損傷確率については炉年あたり10-4より小さくするとともに、新規の原子動力プラントについては10-5より小さくするとの目標を提示した。放射性物質が大量に放出される確率については、炉年あたり現有のプラントが10-5、新規プラントが10-6を目標として掲げた。

  国家環境保護総局(当時)と清華大学等が2007年にまとめた「第2世代改良型原子力発電所の安全水準の総合評価報告」によると、大亜湾、嶺澳1期、嶺澳2期の各原子力発電所の炉心損傷確率は、それぞれ炉年あたり2.13×10-5、1.94×10-5、1.53×10-5と試算された。これに基づくと、運転中の嶺澳2期に加え建設中の原子力発電所で多数採用されている第2世代改良型の「CPR1000」は、原子力安全規画で示された安全要求をクリアーしていない。ちなみに「AP1000」は、外部事象と内部事象による炉心溶融確率と大量の放射性物質が放出される確率が、それぞれ炉年あたり5.08×10-7、5.92×10-8という。原子力安全規画に従えば、「CPR1000」は新規に建設される原子力発電所では採用できないことになる。

  一方、国家戦略性新興産業発展規画では第3世代原子力発電技術の消化吸収・再イノベーションを加速し、第3世代原子力発電所の建設を統一的に計画することが明記された。「第3世代原子力発電技術の消化吸収・再イノベーション」とは、とりもなおさず「AP1000」と、同型炉をベースに開発が行われている中国が独自に知的財産権を持つ「CAP1400」(140万kW)のことであり、原子力安全規画の安全要求と照らし合わせて見ると、新規に建設される原子力発電所は(当面?)「AP1000」に一本化するということが読み取れる。

  この通りだとすると、中国核工業集団公司と広東核電集団有限公司が独自に開発している第3世代炉の帰趨に焦点が移る。両社は、輸出も視野に入れて、それぞれ「ACP1000」と「ACPR1000」という100万kW級の第3世代PWRを開発しており、初号機の着工も具体化してきている。「AP1000」への一本化が国の方針ということであれば、「ACP1000」と「ACPR1000」の目がなくなる。

  もちろん、「AP1000」はウェスチングハウス社が知的財産権を持つため中国として輸出はできない。そうなると、国内では「AP1000」と「CAP1400」を“統一的”に建設し、輸出用には「CAP1400」を利用することが考えられるが、中国核工業集団公司と広東核電集団有限公司は、輸出用の炉型まで「CAP1400」で一本化することに合意したのか。

  ちなみに、中国国家エネルギー局とアルゼンチン計画・公共投資・サービス省との間で6月に結ばれた原子力協力に関する協定では、アルゼンチンで計画されている原子力発電所に「ACP1000」を採用するにあたって、中国核工業集団公司とアルゼンチン原子力委員会、アルゼンチン原子力発電会社が共同で研究するという内容が盛り込まれた。国営のアルゼンチン原子力発電会社は、中国核工業集団公司が開発している「ACP1000」に対して技術承認資格予備審査証明書を発給している。

  今後の中国の原子力発電開発が「AP1000」を中心に回っていくことは間違いなさそうだが、詳細は原子力発電中長期計画の改定版と原子力発電安全規画の公表を待たなければならない。(執筆者:窪田秀雄 日本テピア・テピア総合研究所副所長 編集担当:サーチナ・メディア事業部)

東芝WHのAP1000を最初に買った中国は輸出可能な独自のバージョンを開発。

  • CPR1000 第2世代改良型
  • ACP1000 中国核工業集団公司 第3世代
  • ACPR1000 広東核電集団有限公司 第3世代
  • CAP1400 中国独自知的財産権で輸出用
既にAP1000の話じゃなくなってる。

サウスキャロライナ州のVCサマー原発2(AP1000)の建設開始は米では30年ぶりの新規建設。

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