Safety measures not implemented yet

Nuclear reactors awaiting restart clearance still in midst of safety measure preparation

http://mainichi.jp/english/english/newsselect/news/20130709p2a00m0na014000c.html

As new nuclear safety regulations touted as the world's toughest went into effect in Japan on July 8, power companies applied for safety assessments of nuclear reactors at five power plants by the country's nuclear regulatory body.

Having seen fuel costs for thermal power stations rise since their nuclear reactors were stopped following the outbreak of the nuclear disaster at Tokyo Electric Power Co.'s Fukushima No. 1 Nuclear Power Plant, the four utilities -- Hokkaido Electric Power Co., Kansai Electric Power Co., Shikoku Electric Power Co. and Kyushu Electric Power Co. -- are aiming for the earliest possible restart of their nuclear reactors, explaining they have taken "all conceivable safety measures."

Of the 10 reactors in question, the No. 3 reactor at Shikoku Electric's Ikata Nuclear Power Plant is believed to be the closest to reactivation. With no active geologic faults on the plant's grounds, safety measures can be instituted at a relatively smooth pace.

"The reactor satisfies regulatory standards," stated Shikoku Electric's Managing Director Susumu Tanikawa, who submitted the 6,000-page application to the Nuclear Regulation Authority (NRA).

However, safety measures at many of other nine reactors are still on their way to implementation. For example, with the exception of Ikata Nuclear Power Plant, none of the nuclear power plants for which applications were submitted have quake-proof emergency facilities. The seismic-isolated emergency building at the Fukushima No. 1 nuclear plant has played a major role in efforts to bring the disaster under control, and such facilities are required at nuclear power stations under the new safety regulations.

Hokkaido Electric explained that rooms at the No. 1 and No. 2 reactors would be used temporarily as emergency response rooms in case operations resume at Tomari Nuclear Power Plant's No. 3 reactor, with the expectation that neither of the former would be reactivated until construction of a new quake-proof emergency facility is completed in March 2014.

Meanwhile, Kansai Electric said conference rooms at its Takahama and Oi nuclear plants would be used as substitutes for full-fledged emergency facilities, and Kyushu Electric is aiming to build a makeshift one for its Sendai Nuclear Power Plant by September.

Also of great interest are power companies' estimates of maximum tsunami elevation near their nuclear plants. Tsunami are not expected to be a problem for Sendai Nuclear Power Plant, because the complex is located at a high enough elevation. The Fukui Prefectural Government, meanwhile, predicts that Takahama Nuclear Power Plant is at risk of facing tsunami up to 3.74 meters high, which would flood the plant. Although the plant's operator, Kansai Electric, noted in its application to the NRA that "analysis was needed," it did not change its original prediction of maximum tsunami at 2.6 meters.

Hokkaido Electric previously predicted tsunami to reach a maximum 9.8 meters at its Tomari Nuclear Power Plant, but revised the figure downward to 7.3 meters, citing the ability of boulders along the shore in front of the complex to weaken the impact of tsunami. There was also a possibility that levee design would be found problematic because of the elevation of the plant, but the utility concluded that a review of the design was unnecessary. This may lead to doubts about the company's calculations.

Active geologic faults pose the biggest challenge for reactor restarts. The new safety standards prohibit the installation of essential facilities above active faults, citing the difficulty in preventing damage. Because members of an NRA investigation team are divided on whether a fault that intersects an emergency seawater intake channel at Oi Nuclear Power Plant is active or not, the agency plans to hold off on a safety assessment at the plant until it reaches a consensus. The NRA has also pointed out that it needs to collect additional data on Takahama Nuclear Power Plant, which will undergo scrutiny in the agency's assessment.

Reactor type and the number of years a reactor has been in operation have been determining factors in the application process. All 10 reactors in question are pressurized water reactors (PWRs) and have been in operation for a relatively short time at 30 years or less. Of the 50 reactors nationwide, 24 are PWRs, which have been given a five-year grace period for the installment of vent filters that eliminate radioactive materials. Meanwhile, the other 26 reactors, including the reactors at the Fukushima No. 1 Nuclear Power Plant, are boiling water reactors, and have not been given a similar grace period. (By Ei Okada, Science and Environment News Department)