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2008年12月24日 (水)

浜岡原発―置き換えしかないのか

2008/12/24

--The Asahi Shimbun, Dec. 23(IHT/Asahi: December 24,2008)

EDITORIAL: Hamaoka nuclear plant

浜岡原発―置き換えしかないのか

Chubu Electric Power Co. has decided to retire two old nuclear reactors and build a new state-of-the-art reactor at the same nuclear power plant. The first-ever reactor "replacement" in the nation will be made at the company's Hamaoka Nuclear Power Station in Shizuoka Prefecture.

 古い原発2基を引退させ、代わりに最新の原発1基をつくる。そんな国内初の「原発の置き換え」に中部電力が踏み切る。静岡県の浜岡原発だ。 

The No. 1 and No. 2 reactors at the Hamaoka plant, which started operation in the late 1970s, have been shut down since 2001 and 2004, respectively, due to accidents and for repair. Chubu Electric initially planned to retrofit the two reactors to raise their earthquake resistance under new safety standards and reopen them in fiscal 2011.

 70年代後半に営業運転を始めた1号機と2号機は、事故や修理で01年と04年から運転を止めている。耐震強度を最新の水準にする工事の後、11年度の運転再開をめざしていた。 

But it has been estimated that the work to make the reactors more quake resistant will cost about 300 billion yen in total and take more than 10 years. The company decided that decommissioning the two aged reactors and building a new one, the No. 6 reactor, would make better economic sense.

 ところが、耐震補強に計3千億円の巨費と10年以上の歳月がかかる見通しになった。このため、「1、2号機を廃炉にして6号機を新設する方が経済的だ」と判断したのだという。 

The Hamaoka plant is located in the middle of a region that seismologists have warned is likely to be struck by a powerful Tokai earthquake in the not-so-distant future. The probability of this dreadful quake hitting the region within three decades has been estimated at 87 percent.

 浜岡原発は、30年以内に87%の確率で起こるとされる東海地震の想定震源域の真ん中にある。

It is quite sensible to shut down the two reactors with questionable seismic reliability. But is it the right decision to build a new reactor at the same site?

耐震強度が心もとない2基を廃炉にする判断は妥当だ。 

 だが、その代わりに6号機を新設するというのはどうだろうか。 

We understand the need for the utility company, which has a duty to ensure a stable supply of electricity, to build a new power reactor that can compensate for the loss of the combined power output of 1.38 million kilowatts of the two reactors that will be put out of service.

 電力の安定供給を確保しなければならない電力会社にとって、廃炉にする2基の合計出力(138万キロワット)と同じくらいの発電施設を新たにつくるのが責務であることはわかる。

In addition, power utilities are under growing pressure to reduce their emissions of greenhouse gases. Replacing the two nuclear reactors with thermal power reactors would increase the company's emissions of carbon dioxide. At Chubu Electric, the share of nuclear power generation in its total power output is significantly lower than the national average among power companies.

It is hardly surprising that the company wants to build a new nuclear reactor, which doesn't spew out CO2 into the atmosphere.

 しかも、いま電力業界は地球温暖化を防ぐ努力を迫られている。廃炉分を火力発電で補えば、二酸化炭素(CO2)の排出が増えてしまう。全発電量に占める原子力の比率が全国平均を大きく下回る中部電力が、CO2を出さない原発の新設をめざそうと考えるのは自然ななりゆきではある。 

But building another nuclear reactor in the region that is likely to be rocked by the formidable Tokai earthquake will only add to the safety concerns among residents. Chubu Electric claims there is no reason to worry about the safety of the new reactor as long as it has enough seismic safety margins.

It will be a tall order, however, to win support for the plan from the local community. Some residents are still fighting a battle at an appeal court to suspend operations of the Nos. 1-4 reactors at the Hamaoka plant.

 だが、東海地震で激しく揺れる危険が大きい場所に原発をつくれば周辺住民はさらなる不安の種を抱え込む。中部電力は「耐震性に十分な余裕があれば安全だ」と説明するが、1~4号機の運転差し止め訴訟の控訴審が続くなか、6号機の新設に理解を求めることには無理があるのではないか。 

Chubu Electric should first consider a wide range of alternatives, including increasing purchases of electricity from other power suppliers' nuclear plants and looking for a new location to build a new nuclear plant.

 中部電力はまず、他社の原発から調達する電力量を増やしたり、新たな立地を模索したり、といった代替策を幅広く検討するべきだ。 

The company's decision, meanwhile, underscores the fact that the nation is now entering an era of reactor retirement when a growing number of aging nuclear reactors will have to be shut down. This is a problem that far transcends the closed reactors at the Hamaoka plant.

 一方、今回の決定は「廃炉の時代」が近づいていることをまざまざと見せつけた。これは浜岡原発にとどまる問題ではない。 

Of the 55 reactors operating across the nation, 17 are 30 years or older. While their anticipated maximum life span is 60 years, it may be more economically sensible to decommission an old reactor and build a new one, considering the costs of maintenance and so forth. Replacing aged reactors will become an increasingly common practice for the industry.

 全国の原発55基のうち、運転開始から30年以上のものが17基ある。最長60年間の運転を想定しているものの、維持コストを考え、廃炉にして新しい原発をつくる判断もあろう。今後、原発の置き換えが珍しくなくなるはずだ。 

What is worrisome is that there are no firmly established procedures for shutting down an old reactor.

 気がかりなのは、廃炉の道筋が完全には整っていない点である。 

Decommissioning a 1.1-million-kilowatt reactor produces 500,000 to 550,000 tons of waste. While it contains no high-level radioactive waste, about 3 percent of the matter is polluted with radioactivity. Some sticky questions remain unsolved, such as where the waste materials from the reactor and its peripheral equipment should be buried.

 110万キロワットの原発を廃炉にすると50万~55万トンの廃棄物が出る。高レベル放射性廃棄物こそないものの、放射能で汚れたものが3%ほど出る。このうち、原子炉や周辺設備などの廃棄物をどこに埋設するかといった懸案は解決されていない。 

It is vital to work out a viable plan for decommissioning reactors before the nuclear retirement era comes into full swing.

 「廃炉の時代」の本番までに、その行程表を詰めていかねばならない。

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