The Nuclear Regulation Authority (NRA) gave de-facto safety clearance to the No. 1 and No. 2 reactors at the Takahama Nuclear Power Station in Fukui Prefecture on Feb. 24, effectively marking the first time for reactors aged over 40 years to pass new safety regulations introduced in the wake of the Fukushima No. 1 Nuclear Power Plant disaster.
While a rule limiting the operational period of reactors to 40 years has been passed in the Diet based on bitter lessons from the Fukushima No. 1 Nuclear Power Plant disaster, the NRA's move shows the country has moved a step forward toward prolonging the service life of aging reactors ahead of the fifth anniversary of the onset of the nuclear catastrophe.
As the government is also setting goals for a future energy mix on the premise of extending reactor operations, the 40-year rule appears destined to be watered down.
"We can overcome technical issues (with aging reactors) if we spend money on them," NRA Chairman Shunichi Tanaka told a press conference on Feb. 24, suggesting that reactors that have been running for over 40 years can be operated for longer if large amounts of money are spent on their refurbishment.
When the NRA was launched in 2012, Tanaka had stated, "My understanding is that reactors reach a turning point after about 40 years," and "It would be quite a challenge to extend the service life (of aging reactors) by 20 years." Tanaka's latest remarks represent a major turnaround in his stance on the matter.
The 40-year rule is based on precedents in the United States, and was included in the revised Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, which came into force in 2013. The then administration led by the Democratic Party of Japan (DPJ) explained in the Diet that the 40-year rule was based on the timing of pressure vessel deterioration resulting from exposure to neutrons. The DPJ government also ruled out the possibility of ordinarily extending the service life of aged reactors by up to 20 years, calling this an "exception."
The Federation of Electric Power Companies of Japan, however, opposed the introduction of the 40-year rule, saying that the rule would undermine technical achievements and spark confusion. The 40-year rule has also been "treated like a nuisance" within the Liberal Democratic Party (LDP), according to a senior LDP official, with legislators elected in prefectures hosting nuclear plants drawing up a statement calling for a review of the rule.
Amid such circumstances, Kansai Electric Power Co., which operates the Takahama nuclear plant, spent some 380 billion yen on the renovation of the plant's four reactors before obtaining de-facto safety clearance from the NRA.
In general, old, flammable cables are used at dated reactors. If nuclear plants are to extend their operations, utilities must implement large-scale fire-prevention measures. Kansai Electric Power Co. replaced 60 percent of old cables -- stretching a total of 1,300 kilometers -- with flame-resistant ones at the No. 1 and 2 reactors at the Takahama plant, and also took measures to prevent fire from spreading by wrapping the remaining cables in fireproof sheets. These efforts won the NRA's de-facto stamp of approval. If such a method is adopted at the seven other nuclear plants in Japan that use similar cables, it could create a loophole in the 40-year rule.
The NRA, meanwhile, is under pressure to accelerate its safety screenings on the two reactors at the Takahama plant. For reactors over 40 years in service to be reactivated, they must not only pass safety screenings but also have their construction plans and the extension of operations approved before the legal deadline. The NRA is now set to conduct full-scale inspections on the pressure vessels and other apparatus at the plant to check the rate of their deterioration. The legal deadline for putting the No. 1 and 2 reactors back into operation is looming on July 7 -- the three-year mark since the new safety regulations came into force -- and the reactors must clear the relevant conditions before that deadline, or else they must be decommissioned.
Since last autumn, the NRA has had workers focus on screening the No. 1 and 2 reactors, effectively giving priority to the Takahama plant over the other plants awaiting screenings. The Feb. 24 issuance of de-facto approval for the two reactors' operation came only 11 months after Kansai Electric Power Co. filed an application for the safety review in March last year.
Swift measures were taken because the NRA may face litigation if a delay in screening results in reactor decommissioning.
There remain many hurdles ahead, however, before the two reactors can be reactivated. The NRA shelved work to examine the quake resistance of equipment inside the reactors until after the safety clearance. Even if the reactors manage to pass the quake resistance evaluations and gain final approval by July, the utility must also build domes shielding against radiation on top of the reactor buildings, among other construction work, in order to have their service life extended. Therefore, the resumption of operations of the two reactors is expected to come sometime after October 2019, even if all conditions are met.
"If the Takahama plant manages to have the extension of the reactors' service life approved, it will serve as a model for other plants in terms of expenses and the response to regulations," said a senior official with a major power company.