Only Pre-Service Inspections Remain Before First Nuclear Plant Restarts in Japan

The Japanese Nuclear Regulatory Authority (NRA) approved Kyushu Electric Power Co.’s operational safety programs for Sendai Nuclear Power Station Units 1 and 2 on May 27.

The approval is the last of three needed by the company to verify that the plant complies with new regulatory requirements implemented as a result of the Fukushima disaster. The process consisted of gaining permission for changes in the reactor installation license, construction work planning approval, and approval of operational safety programs.  The next step necessary is for pre-service inspections to be completed (Figure 1).

1. Steps to restart.
Sendai Nuclear Power Station Units 1 and 2 have been granted all approvals in the three-step review process. Courtesy: Nuclear Regulatory Authority, Japan

It has been a long process getting to this point. Kyushu filed its application on July 8, 2013. On Sept. 10, 2014, the NRA granted the company permission to make changes to the reactor installation of Sendai Units 1 and 2. Following approvals from the mayor and local assembly of Satsumasendai City, the units received Kagoshima Prefecture Governor Yuichiro Ito’s approval to restart on Nov. 7, 2014.

Legal petitions to halt the restart posed another hurdle, but unlike the court ruling that blocked the restart of Kansai Electric Power Co.’s Takahama nuclear plant, the Japanese court rejected the petition against Sendai on Apr. 22, 2015. Now it appears one of the units could recommence operation as early as July with the second unit restarting a couple of months later.

Some examples of measures taken to prevent common cause failures at Japanese sites following Fukushima include:

  • Requiring two independent sources of offsite power,
  • Installation of a third permanently installed emergency diesel generator (EDG)—in addition to the two previously required EDGs—plus two additional mobile units and fuel storage capacity for seven days of operation, and
  • Increased DC power capacity to accommodate 24 hours of use, plus a second permanent system and a mobile system each with 24 hours of additional capacity.

Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)

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