Nuclear station sluggish to restart after earthquake

Kashiwazaki-Kariwa restart timeline details TEPCO's BWR and ABWR unit status, IAEA inspection findings, seismic safety reviews, maintenance outages, refueling plans, and MW output updates following the earthquake shutdown and staged restarts.

Kashiwazaki-Kariwa Nuclear Power Station, which is 240 kilometers northwest of Tokyo in the Niigata prefecture, experienced a shutdown due to a massive earthquake on July 16, 2007. The epicenter of the Chuuetsu Offshore Earthquake, measured at magnitude 6.6, occurred off the coast of Niigata, some 19 kilometers from Kashiwazaki-Kariwa.

Kashiwazaki-Kariwa, which is owned and operated by Tokyo Electric Power Company Incorporated TEPCO, began operations in 1985 and has an output of 7,965 megawatts MW, making it the world's largest nuclear plant by capacity worldwide, generated by five 1,067-MW boiling water reactors and two 1,315-MW advanced boiling water reactors.

At the time of the earthquake, units 1, 5 and 6 were down for scheduled maintenance. The remaining four units powered down safely in response to the earthquake as per protocol. TEPCO wanted to resume operations the day following the earthquake, but was ordered to keep Kashiwazaki-Kariwa powered down by the Ministry of Economy, Trade and Industry METI. The International Atomic Energy Agency IAEA conducted an inspection of the power station, concluding that no significant damage had been sustained and that TEPCO should re-evaluate seismic safety, even as reports of a nuclear leak raised additional concerns.

Kashiwazaki-Kariwa remained down for 21 months and was brought back online in May 2009, after Unit 7 was deemed seismically fit to resume operations and as TEPCO resumed operations at the quake-hit reactor. Units 6 and 1 soon followed.

According to recent information provided by TEPCO, units 1 and 7 have resumed normal operations, following restart approval by the energy authority, and Unit 5 is undergoing a full-capacity test run. Unit 5 is expected to enter normal operations very soon, and Unit 6 is down for scheduled maintenance. BWR units 2, 3 and 4 are still down and under inspection with no definite restart dates.

In the next year, units 7 and 6 are expected to undergo scheduled inspection and refueling, as other utilities like Kansai Electric plan to restart thermal units across the grid. Part of the inspection will include an earthquake resistance examination. Unit 7 will be powered down for three months from the third quarter of 2011 to the fourth quarter of 2011, while Unit 6's three-month outage is expected to take place starting in the first quarter of 2012. Total investment value for inspection and refueling is expected to be about $218 million per unit.

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