Kansai Electric Power Co.'s request to renew its license to operate a nearly 40-year-old reactor could be in trouble if signals from Prime Minister Naoto Kan are an indication.
Kansai Electric Power Co.'s request to renew its license to operate a nearly 40-year-old reactor could be in trouble if signals from Prime Minister Naoto Kan are an indication.
The utility submitted a report to the government July 22 seeking permission to extend operations of the No. 2 reactor at its Mihama nuclear plant in Fukui Prefecture, saying it poses no safety problems.
The reactor, put into service in July 1972, is the fourth oldest in the country's fleet of 54.
The request is the first such since the crisis began at the Fukushima No. 1 nuclear plant on March 11.
Kan indicated in the Upper House Budget Committee session July 22 that extending the operational life of an aged reactor would be as difficult as building a new reactor, given the ongoing nuclear crisis.
"I am afraid that winning public support for extending the life of existing nuclear reactors and construction of new reactors replacing those will not be easy," Kan said.
He was responding to Jiro Ono, a member of Your Party, who asked for a timetable on Kan's idea to eventually get rid of all the nuclear power plants in Japan.
The No. 1 reactor at the Fukushima No. 1 nuclear plant went live in March 1971. The other five reactors at the crippled plant started operating in the 1970s.
However, Chief Cabinet Secretary Yukio Edano indicated at a news conference July 22 that a decision on license renewal will not be made under the Kan administration.
"The Nuclear and Industrial Safety Agency and the Nuclear Safety Commission of Japan bear the primary responsibility for the matter from both technical and safety viewpoints," Edano said.
He added that the Mihama reactor, just like the rest of the country's reactors, must undergo a "stress test."
Kansai Electric said that it has confirmed that the reactor, with a capacity of 0.5 gigawatts, is operable beyond 40 years if additional safety steps are taken for some devices.
But the government of Fukui Prefecture, which hosts the Mihama plant, said the utility's safety assessment for the reactor is based on safety standards set before the accident at the Fukushima plant, making it inadequate.
"People in the prefecture will not accept (extended operations) if its safety standards remain the same as before the (Fukushima) accident," said Homare Mitsuda, deputy governor of Fukui Prefecture, after being briefed on the company's planned license renewal request.
The prefecture hosts 13 reactors, the most in the nation.
Eleven are operated by Kansai Electric. Of those, seven have operated for more than 30 years. In five years, three more reactors, apart from the No. 1 and No. 2 reactors at the Mihama plant, will exceed 40 years in operation.
Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, was critical of Kansai Electric's plan to continue to operate the reactor.
"Introducing something new is more rational in terms of economy and safety, instead of continuing to operate an old reactor with a smaller capacity," he said.
In 1996, facing opposition to construction of new reactors, the government decided that the nation's existing reactors could be operated for 60 years as long as their safety was confirmed.
Two reactors in Japan have been in operation longer than 40 years.
The No. 1 reactor at Japan Atomic Power Co.'s Tsuruga nuclear plant in Fukui Prefecture began operation in March 1970 with a capacity of 0.357 gigawatts.
Kansai Electric's No. 1 reactor with a capacity of 0.34 gigawatts at its Mihama plant has been in service since November 1970.
Globally, the question of how to deal with aging reactors is a growing challenge.
There are about 20 reactors in the United States, Switzerland, India and elsewhere that were put into operation at least 40 years ago.
In Japan, 12 reactors, except for six at the Fukushima No. 1 plant, went into service in 1970s as the country's first reactors.
Electric power companies told their host governments back then that the lifetime of the reactors would be 30-40 years, a mainstream view at that time.
The pressure vessels--the heart of the reactors along with outer containment vessels--become brittle due to the constant bombardment of neutrons produced during nuclear fission reactions.
Pressure vessels were expected to remain sturdy enough for a maximum 40 years, based on the designs of U.S. reactors that Japanese engineers emulated.
But advances in analysis technology have led to such reactor lifetime projections being extended. As reactors age, much of the equipment is replaced.
In Japan, no pressure vessels or containment vessels have been replaced.
By regulation, any reactor that has operated for more than 30 years is required to undergo extra checks, in addition to routine annual checks.
For reactors that have been in service for more than 30 years, the operators are obliged to compile an assessment report every 10 years to win license renewal.
The inspections include an ultrasound of welds, which are relatively vulnerable, and monitoring of piping and concrete parts for possible deterioration.
Kansai Electric went ahead and submitted its planned request for an extension for the No. 2 Mihama reactor because the deadline was approaching.
Ordinarily, it takes the government from six to 11 months to decide whether to renew a nuclear power plant license, according to NISA, the nuclear industry regulator under the industry ministry.