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2008年12月24日 (水)



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

EDITORIAL: Hamaoka nuclear plant


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.


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.


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.


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.


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?



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.


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.


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.


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.


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.


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.


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


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.


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



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