Japanese reactor resumes operation after periodic inspection

09 December 2016

Kyushu Electric Power Company yesterday began the process of restarting the reactor of unit 1 at its Sendai nuclear power plant in Japan's Kagoshima prefecture following a periodic inspection. The prefectural governor had opposed the restart of the unit, which resumed operation in August 2015 following a shutdown of the country's nuclear fleet.

Sendai - 460 (JAIF)
Kyushu's two-unit Sendai plant (Image: JAIF)

Sendai 1 was the first of Japan's idled reactors to be restarted after confirmation that it meets new safety standards introduced in mid-2013 following the March 2011 accident at the Fukushima Daiichi plant. Unit 1 was restarted August 2015, followed by Sendai 2 last October. Sendai 1 was taken offline on 6 October for a routine outage.

Kyushu began the operation to extract the control rods from the reactor's core at 9.30pm yesterday, allowing the fission process to begin, the Japan Atomic Industrial Forum (JAIF) reported today.

The utility said in a 7 December statement it expected Sendai 1 to achieve criticality - a controlled self-sustaining nuclear fission chain reaction - today and that power generation would resume on 11 December. Kyushu will then gradually increase output from the unit, with normal operation scheduled to be resumed in early January.

It is the first unit to undergo a periodic inspection following its restart after meeting new regulatory standards, JAIF noted.

Satoshi Mitazono, the recently-elected governor of Kagoshima prefecture, made a request on 26 August that the operation of the two Sendai units be suspended immediately for safety checks. However, Kyushu rejected this request in early September, saying it would carry out additional safety checks during planned routine outages. The governor repeated his request, but Kyushu again rejected it. Mitazono conceded in October he does not actually have the authority to tell Kyushu to keep Sendai 1 offline.

Sendai 2 is scheduled to be taken offline for a periodic inspection, together with additional safety checks, on 16 December.

To date, five Japanese reactors have been given final approval to restart, although two of these - units 3 and 4 of Kansai Electric Power Company's Takahama plant - have remained offline due to a legal challenge. Another 20 reactors are moving through the restart process, which has been prioritised to bring on the most-needed reactors first, in the localities and prefectures more supportive of restart.

Researched and written
by World Nuclear News