8 Août 2016
August 8, 2016
Moves by the Nuclear Regulation Authority (NRA) to give the green light to the extension of operations at aging nuclear reactors have raised serious questions about the safety of atomic power plants. The extension of the lifespan of nuclear reactors, which had been regarded as an exception, now happens regularly.
The recent moves represent a departure from the new safety regulations on atomic power stations, which were enforced by drastically reviewing older regulations by learning lessons from the crisis at the tsunami-hi Fukushima No. 1 Nuclear Power Plant.
The NRA approved a draft screening document that effectively recognizes the No. 3 reactor at the Mihama Nuclear Power Plant in Fukui Prefecture -- which its operator Kansai Electric Power Co. (KEPCO) intends to continue running even after its 40-year lifespan -- meets new safety standards. If the reactor passes additional screening tests by the end of November 2016, KEPCO can continue operating the reactor until 2036 at the latest.
This is the third aging nuclear reactor for which the NRA has approved the extension of operations following the No. 1 and 2 reactors at KEPCO's Takahama plant for which the authority gave the green light in June.
Following the outbreak of the Fukushima nuclear crisis in March 2011, legislation was amended to limit the lifespan of nuclear reactors to 40 years, in principle, with the aim of reducing the risks of accidents involving aging reactors. By the time of the outbreak of the nuclear disaster, about 35 to 40 years had passed since Fukushima No. 1 plant's No. 1, 2 and 3 reactors, where meltdowns occurred, began operations.
The then administration led by the Democratic Party of Japan (DPJ) explained that the 40-year lifespan was set based on the time it is estimated to take before the reactor pressure vessel has deteriorated after being exposed to neutrons.
Apart from the DPJ, which was subsequently reorganized into the Democratic Party earlier this year, the then opposition Liberal Democratic Party (LDP) and Komeito voted for a bill to revise the relevant legislation. A clause allowing for the lifespan to be extended only once by up to 20 years as an exception upon the NRA's approval was incorporated into the law.
Since Japan is an earthquake-prone country and has numerous volcanos, it is highly risky to continue relying on nuclear plants. Therefore, many members of the public apparently deemed that the 40-year rule was reasonable.
To enhance the safety of nuclear plants and phase out nuclear power, the government and electric power companies that operate atomic power stations should stick to the 40-year rule.
Experts have pointed out that there are limits to enhancing the safety of aging nuclear reactors, noting that it is technically difficult to change the basic design of the facilities and their arrangement although their parts can be replaced with new ones. The need to hand over maintenance techniques from generation to generation also poses a serious challenge.
If the risks involving such aging reactors are taken seriously, screenings of applications for the extension of operations at aging nuclear plants should be far stricter than those for the younger nuclear plants.
However, the NRA appears to have helped KEPCO pass the screening for the extension of the lifespans of the utility's Takahama and Mihama plants.
July 2016 was the deadline for permitting the extension of the lifespan of the Takahama plant, and late November is the deadline for the Mihama power station shortly before the 40th year will have passed since the start of its operation.
Since the screening periods for the Takahama and Mihama nuclear plants were limited, the NRA prioritized inspections on these plants over other power stations, concentrating its personnel on the screening of these power stations.
Moreover, the NRA postponed experiments of exposing key devices at these power stations to vibrations to test their quake resistance until after the permission of the extension of their lifespan is granted in order to prevent time from running out for the screening.
The NRA says that it would not revoke its permission even if the experiments were to find that the plants were not sufficiently quake resistant, and instead reconfirm their safety after their operator takes additional safety measures. Some members of the NRA criticized the move saying that redoing the safety confirmation would damage the public's understanding of the NRA.
It has been pointed out that cables that are easy to burn are used in aging nuclear plants. The new regulatory standards require nuclear plant operators to make all cables fire retardant. However, it takes a long time and costs much money to replace all cables at atomic power stations with flame-retardant cables. The NRA requires KEPCO to cover cables that are difficult to be replaced with flame-retardant ones with fire-proof sheets. However, questions remain as to whether the measure will ensure the same level of safety as the use of flame-retardant cables.
NRA Chairman Shunichi Tanaka had said when he assumed his post that it's "extremely difficult to extend" the operation of aging reactors beyond the 40-year limit. However, he has since changed his view to the effect that "technical challenges can be overcome if necessary money is spent." He appears as if he were speaking on behalf of power companies.
It has been decided to decommission six aging reactors following the outbreak of the Fukushima nuclear disaster in March 2011, in addition to those operated by Tokyo Electric Power Co., the operator of the crippled Fukushima plant. However, all these nuclear reactors are small-scale ones, each with an output of approximately 300,000 to 500,000 kilowatts.
In contrast, Mihama's No. 3 and Takahama's No. 1 and 2 reactors have an output capacity of about 800,000 kilowatts, larger than those that are set to be decommissioned. KEPCO estimates that it will spend over 200 billion yen for the Takahama reactors and 165 billion yen for the Mihama reactor as funds to implement safety measures. Despite such huge costs, KEPCO is determined to extend the lifespans of these plants because the plants will be effective in increasing the company's profitability since fuel costs for nuclear plants are far lower than those for thermal power stations. If Takahama's No. 1 and 2 reactors are put online, it is estimated to push up the company's profits by about 9 billion yen a month.
Fifteen reactors across the country, including Mihama's No. 3 reactor, are to surpass their 40-year lifespan over the next decade. Utilities are likely to apply for permission to extend the lifespan of many of these reactors if they deem that the extension will be profitable for the companies even if safety measures cost the operators massive amounts of money. The extension of the lifespans of the Mihama and Takahama plants will serve as role models for such efforts.
As such, decisions on whether to decommission aging reactors will be effectively left to the discretion of power companies based on economic principles, reducing the exceptional clause in the law to a mere facade.
The provision for the 40-year lifespan was incorporated in the legislation to prioritize the safety of nuclear plants over power companies' profits.
Furthermore, the government of Prime Minister Shinzo Abe has established a goal of setting the ratio of nuclear power to Japan's entire power supply at 20 to 22 percent in fiscal 2030. If the 40-year rule were to be thoroughly observed, the ratio would be around 15 percent even if all the existing reactors and those under construction were to be fully in operation. This will encourage power companies to extend the lifespans of their nuclear plants
Such a policy cannot respond to the wishes of numerous members of the general public to build a society that will not rely on atomic power at an early date. As a country that has experienced a severe nuclear accident, Japan should phase out nuclear power rather than extending the lifespan of aging reactors.