Japan’s Nuclear Regulation Authority (NRA) on 20 April effectively approved the restart of unit 3 at Shikoku Electric Power Company’s Ikata NPP in Ehime prefecture, and potentially of units 1 and 2 at Kansai Electric Power Co’s Takahama NPP in Fukui prefecture, subject to final inspections.

NRA requires plant operators to apply for: permission to make changes to the reactor installation; approval of their construction plan to strengthen the plant; and, approval of the plant’s operational safety programmes. Operators must install specific safety-enhancing equipment within five years of a reactor engineering work programme being approved.

Shikoku submitted the engineering work programme for Ikata 3’s 846MWe pressurised water reactor (PWR) in July 2013, and it was approved in July 2915. This means the NRA considers the reactor, and the plant in general, to be safe for operation. Shikoku’s ‘construction plan’ for strengthening Ikata was approved on 23 March. Following this third approval of its operational safety programmes, Shikoku can request final pre-operational safety inspections enabling it to resume operation of the unit. It will be the fifth reactor to resume operation under new safety standards introduced following the March 2011 Fukushima Daiichi accident.

Unit 1 of Kyushu Electric Power Company’s Sendai plant in Kagoshima prefecture restarted last August, followed by Sendai 2 in October. Unit 3 of Kansai Electric Power Company’s Takahama NPP restarted on 29 January. Takahama 4 restarted on 26 February, but has been offline since 29 February following an automatic shutdown of the reactor due to a "main transformer/generator internal failure". However, an injunction imposed by a district court on 9 March led to unit 3 being taken offline as well and both units have since remained closed.

NRA has also now issued a screening certificate for units 1 and 2 at Takahama NPP, approving their safety measures. It is the first screening certificate for reactors that are to be operated for more than 40 years. A draft screening certificate issued in February has been subject to a public consultation and the final certificate includes revisions based on the 606 opinions received. The decision also needed confirmation from the Japan Atomic Energy Commission and the Ministry of Economy, Trade and Industry.

The Nuclear Reactor Regulation Law, revised after Fukushima, limits the duration of operations of nuclear reactors to 40 years in principle but allows extensions of up to 20 years if approved. Kansai Electric applied to NRA in March 2015 for inspections of the units (780 MWe (net) pressurized water reactors) to check their compatibility with the revised standards for extension of unit 1’s operations on until November 2034 and unit 2’s until November 2035.

Earlier in February, NRA judged that fire prevention measures on electric cables — a problem unique to older reactors — and other revised measures met the regulations. Kansai Electric still requires checks by 7 July on whether the facilities have deteriorated with age. This includes three outstanding issues: safety measures, detailed designs and extension of operations. The remaining conditions also include an assessment of detailed plans on quake resistance.

Earlier in April, anti-nuclear groups filed a lawsuit with a district court saying the extended operation of the two units poses a danger. The two 780MWe PWR units have been in commercial operation since November 1974 and November 1975. Kansai Electric says putting the reactors back online will take more than three years, in order to complete the safety work. It could be longer if legal proceedings are launched.