Kyushu misses deadline for Sendai 1 emergency facilities

16 March 2020

Kyushu Electric Power Company today took unit 1 of its Sendai nuclear power plant offline as it had failed to meet the deadline for completion of a back-up control centre. It's the first time operation of a Japanese reactor has been temporarily suspended for this reason. It plans to take unit 2 offline in May for the same reason.

The Sendai plant (Image: Kyushu)

Bunkered back-up control centres are a requirement of new regulations introduced in July 2013 in response to the March 2011 accident at the Fukushima Daiichi plant. The Nuclear Regulation Authority (NRA) ruled in November 2015 that such facilities must be completed within five years after regulatory approval of each plant's engineering and construction work programme. That programme is the second step in NRA's three-step process of assessing reactor safety prior to restart. The third and final stage includes pre-operational inspections to ensure the unit meets new safety requirements.

Unit 1 of the Sendai plant in Kagoshima prefecture was the first reactor to be restarted in August 2015, followed by Sendai 2 in October that year. The NRA approved the detailed design of the units in March and May 2015, respectively. Under the regulations, Kyushu had until 18 March and 22 May 2020 to complete the back-up control centres at Sendai units 1 and 2, which are both 890 MWe pressurised water reactors.

Kyushu began reducing the power output of Sendai 1 at 2:30am. Power generation ended at 9:00am and the reactor was declared offline at 1:01pm. It will conduct routine inspections of the Sendai 1 during its suspension, noting that these are expected to be completed in about 10 months. Last October, the company said it planned to restart generation at the unit on 26 December this year, with commercial operation resuming in January 2021.

Both Kyushu and Kansai Electric Power Company had earlier informed the NRA they expected construction of the back-up facilities to be delayed by about one year. Kansai is expected to suspend operation of units 3 and 4 of its Takahama plant in Fukui Prefecture in August and October, respectively. Other utilities have also said there will be delays of up to two-and-a-half years in completion of back-up centres at their reactors.

If a centre is not completed by one week before the deadline, the NRA can order a utility to suspend operation of a reactor. Under the new rules, an operator must place a unit in cold shutdown - where coolant water is at less than 100ºC - within a day of the unmet deadline.

So far, nine of Japan's 39 operable reactors have cleared inspections confirming they meet the new regulatory safety standards and have resumed operation. These are: Kyushu's Sendai units 1 and 2 and Genkai units 3 and 4; Shikoku's Ikata unit 3; and Kansai's Takahama units 3 and 4 and Ohi units 3 and 4. Another 17 reactors have applied to restart.

Researched and written by World Nuclear News