Revision of the Seismic Safety Assessment Plan, Etc. for Reactors No. 1 & 2, Hamaoka Nuclear Power Station

The Nuclear Safety Commission (NSC) of Japan revised its "Seismic Design Evaluation Guidelines for Nuclear Power Reactor Facilities" on September 19, 2006.  By way of response, based upon instructions issued by the Nuclear and Industrial Safety Agency (NISA) on the following day (September 20, 2006), in light of the revised Seismic Durability Guidelines (the New Seismic Durability Guidelines), Chubu Electric Power submitted a Seismic Safety Assessment Plan for the Hamaoka Nuclear Power Station on October 18, 2006.

Following on from these developments, due to the occurrence of the decommissioning phase of Reactors No. 1 & 2 of the Hamaoka Nuclear Power Station, that was entered into as of November 18, 2009, on both December 25, 2009 and February 01, 2012, instructions were issued by NISA regarding implementation of seismic safety assessments, etc. and revision of the Seismic Safety Assessment Plan, in light of the new Seismic Durability Guidelines that were based upon the condition of facilities at the Hamaoka Nuclear Power Station.

Based on these instructions, Chubu Electric Power revised the Seismic Safety Assessment Plan, etc. for Reactors No. 1 & 2, Hamaoka Nuclear Power Station, and submitted this revised documentation to NISA today.

1.  Overview of Assessment:

(1) Reactor No. 1, Hamaoka Nuclear Power Station

Concerning Reactor No. 1, in considering that there is only one spent fuel rod being stored in the spentfuel-rod storage facility of this reactor, based upon the instructions, in place of a seismic safety assessment of the facilities being conducted, an assessment shall be conducted concerning there being no danger of excessive radiation-exposure levels in surrounding communities, even based upon a premise of radiation escaping to the environment outside the facilities from those radioactive materials that are stored within the storage facilities.

(2) Reactor No. 2, Hamaoka Nuclear Power Station

Concerning Reactor No. 2, in considering that there are some 1,312 spent and new fuel rods being stored in the spent-fuel-rod storage facility of this reactor, a seismic safety assessment(Note) shall be conducted on the necessary facilities to ensure all the "cooling functions," "sub-criticality functions," and "containment functions."

2.  Assessment Process:

Chubu Electric Power plans to deliver an assessment results report to NISA in late March.

(Note)Concerning the "standard ground motion Ss" to be used in seismic safety assessments, the standard ground motion Ss (horizontal-motion peak acceleration of 800 cm/s²) found in the "Seismic Safety Assessment Results Report in Response to Revisions of the ‘Seismic Design Evaluation Guidelines for Nuclear Power Reactor Facilities' for Reactor No. 4, Hamaoka Nuclear Power Station" (submitted January 25, 2007) shall be used.

Note: concerning seismic safety assessments, knowledge obtained from seismic events such as the Suruga Bay Earthquake and the Great East Japan Earthquake, etc. shall be appropriately reflected in seismic safety assessments wherever necessary.