Tohoku Electric Power Co. applied Friday for a safety assessment of its No. 2 reactor at the Onagawa power plant in Miyagi Prefecture, making it the 16th unit that will be checked before a possible restart.
The Onagawa plant was the closed nuclear complex to the epicenter of the magnitude-9.0 earthquake in March 2011, which generating tsunami that set off the crisis at Tokyo Electric Power Co.’s Fukushima No. 1 plant in neighboring Fukushima Prefecture.
Although the Onagawa plant was rattled by the huge earthquake, all three reactors halted automatically and are now undergoing periodic checkups.
All of Japan’s commercial reactors are offline and their operators have to satisfy new safety requirements introduced in July to be allowed to resume operation.
Four of the 16 reactors up for safety checks, including the Onagawa plant’s No. 2 unit, are boiling water reactors — the same type as the reactors that suffered meltdowns at the Fukushima No. 1 plant.
Boiling water reactors have to undergo major refurbishment before resuming operation because they have to be equipped with a filtered venting system to allow radioactive substances to be released to prevent damage to the reactor’s primary containment vessel during an emergency.
Tohoku Electric Power plans to finish installing the venting system in the business year starting in April 2015.
Pressurized water reactors, meanwhile, are given a five-year moratorium to meet the requirement because they are housed in containers larger than those of BWRs, making it less pressing to install the system.