設計缺陷誘發福島核災難Design Flaw Fueled Nuclear Disaster

設計缺陷誘發福島核災難

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華 爾街日報》在仔細研究之後發現﹐東京電力公司（Tokyo Electric Power Co.）的一些高級工程師幾年前就知道該公司在福島縣的核反應堆中有五座存在可能發生危險的設計缺陷﹐但該公司並未完全升級這些反應堆。因此地震來襲時﹐ 這些核反應堆注定要發生故障。

東京電力公司使用兩套不同的設計方案保護其在福島的10座核反應堆。3月11日強震來襲時﹐其中五座使用較新設計的反應堆經受住了接踵而來的浪高近14米的海嘯的沖擊﹐關鍵性的冷卻系統正常運作﹐這五座反應堆安全關閉。

東京電力公司

在一次爆炸中損毀的福島核電站一號反應堆。

但使用較舊設計的另外四座反應堆的冷卻系統卻出現了故障﹐備用柴油發電機和電氣開關設備被海水淹沒。因此﹐其中三座反應堆的核燃料熔毀﹐好幾座反應堆廠房發生爆炸﹐最終釀成了自切爾諾貝利核事故以來最嚴重的輻射泄漏危機。

海 嘯暴露了一些核電站在設計上的致命缺陷：一個底面積只有一張餐桌大小的電氣開關設備的擺放位置令人質疑。在設計較新的核電站內﹐這一設備與反應堆一起放置 在一座堅固的建築物內。在設計較舊的核電站內﹐這一設備被安放在缺乏保護的附屬建築內。這個附屬建築是最初設計遺留下來的。海嘯襲來之際﹐這些電氣開關被 沖毀﹐令正在運轉的發電機停止發電。

這篇報道是基於對東京電力公司12位現任和前任高級工程師的採訪寫就而成的﹐有好幾位曾在上世紀70 年代這一對後世命運有決定性影響的設計最終拍板時深入參與其中。一些工程師說﹐幾十年來東京電力公司曾有過機會改造升級最老的核反應堆。這些人認為﹐自 滿、削減成本的壓力以及寬鬆的監管是造成東京電力公司始終沒有這麼做的原因。

88歲的豐田正敏（Masatoshi Toyota）說﹐毫無疑問﹐東京電力公司早該讓整個福島核電站全面採用新的設計。豐田正敏以前是東京電力公司的高層﹐曾負責監督核反應堆廠房。他說他為自己沒有注意到設計缺陷並在後來改正其中一些問題而感到自責。

東京電力公司的一位發言人拒絕對此事發表評論﹐稱日本政府就事故原因展開的調查還在進行之中。

日 本並非惟一在與核反應堆老化作鬥爭的國家。美國有幾十座反應堆的運營時間超過30年﹐其中23座與福島核電站老舊的反應堆一樣使用通用電氣公司 （General Electric Co.）的設計。還有幾座在未來幾年面臨重新獲得牌照的惡戰。其它國家裡﹐德國和瑞士已經決定逐步淘汰老化的核電站﹐並最終棄用核電。

福島核電站所有反應堆（包括較新的）都是基於通用電氣公司的設計。該公司仍然維係定期維修在日本的通用電氣反應堆的利潤豐厚的合同。通用電氣與合作伙伴日立公司（Hitachi Ltd.）一同參與了一項全球性活動﹐以延長其老化核電站的壽命。

通用電氣公司說﹐福島核反應堆的任何缺陷與該公司無關﹐因為東京電力公司負責變更設計。通用電氣公司發言人斯坦格爾（Catherine Stengel）說﹐福島第一核電站應急柴油發電機的擺放位置經過了東京電力公司和監管部門的審核批准。

Norihiko Shirouzu / Chester Dawson

Design Flaw Fueled Nuclear Disaster

Some senior engineers at Tokyo Electric Power Co. knew for years that five of its nuclear reactors in Fukushima prefecture had a potentially dangerous design flaw, but the company didn't fully upgrade them, dooming them to failure when the earthquake hit, a Wall Street Journal examination of the disaster shows.

The company used two different designs for safeguarding its 10 reactors in Fukushima. When the devastating quake struck on March 11, the five reactors with the newer design withstood the resulting 45-foot tsunami without their vital cooling systems failing. Those reactors shut down safely.

But the cooling systems failed at four reactors with the older design. Backup diesel generators and electrical-switching equipment were swamped by seawater. As a result, fuel melted down at three reactors and there were explosions at several reactor buildings, culminating in the largest release of radiation since Chernobyl.

The tsunami exposed an Achilles heel in the design of some of the plants: the questionable placement of a single kitchen-table-size electric-switching station. At newer plants, the station was in a robust building that also housed the reactor. In others, it stood in a poorly protected outbuilding─a relic of the original design. When the tsunami hit, those switches were knocked out, rendering operating generators useless.

This article is based on interviews with a dozen current and former senior Tokyo Electric Power engineers, including several who were intimately involved when the fateful design decisions were made in the 1970s. Some of them say the company, known as Tepco, had opportunities over the decades to retrofit the oldest reactors. They blame a combination of complacency, cost-cutting pressures and lax regulation for the failure to do so.

'There's no doubt Tepco should have applied new designs' throughout Fukushima, says Masatoshi Toyota, 88 years old, once a top Tepco executive who helped oversee the building of the reactors. He says he blames himself for not noticing the design problems and correcting some of them later.

A spokesman for Tepco declined to comment for this story, citing the Japanese government's ongoing investigation into the cause of the accident.

Japan isn't the only nation grappling with aging nuclear reactors. The U.S. has dozens of reactors that have operated for more than 30 years, and 23 with the same General Electric Co. design as the older Fukushima reactors. Several face fights over relicensing in the next few years. Elsewhere, Germany and Switzerland have decided to phase out their aging plants and drop nuclear power altogether.

All the Fukushima plants, including the newer ones, were based on GE designs. GE maintained lucrative contracts to service GE reactors in Japan and was engaged with partner Hitachi Ltd. in a global campaign to extend the lives of its aging plants.

GE said any flaws at the Fukushima reactors weren't its fault because Tepco was in charge of design changes. 'The location of emergency diesel generators at the Fukushima Daiichi plant were reviewed and approved by Tepco and regulatory authorities,' said GE spokeswoman Catherine Stengel.