Concerning Report on Re-Examination of Hamaoka Nuclear Power Station Seismic Safety Evaluation Reports
January 20, 2012
Chubu Electric Power Co.,Inc.
In consideration of input data errors in a nuclear power station seismic safety evaluation as found at another electric power company, the Nuclear and Industrial Safety Agency (NISA) recently issued instructions* to Chubu Electric Power to conduct a re-examination of its seismic safety evaluation reports on Hamaoka Nuclear Power Station. This is to announce that Chubu Electric Power has conducted that re-examination and today submitted its re-examination report to NISA.
1. Content of NISA instructions (overview)
In light of seismic response analysis model input data errors that occurred in the seismic safety evaluation of the Takahama Nuclear Power Plant Units 3 and 4 of The Kansai Electric Power Co., Inc., and in light of similar occurrences from other companies, nuclear power businesses that were instructed to conduct evaluations of seismic safety of existing nuclear power reactor facilities as a result of revisions to the "Seismic Design Evaluation Guideline for Nuclear Power Reactor Facilities" must study whether there are errors in the entered data and established conditions for analysis relating to the seismic safety evaluation of buildings, structures, equipment and piping that are important to safety, even if this analysis was done by a contractor; must re-examine their seismic safety evaluation reports; and prior to reporting comprehensive safety evaluations that concern seismic safety margins to NISA, must have such reports checked by NISA.
2. Report content (overview)
When we conducted the re-examination of our seismic safety evaluation report on Hamaoka Nuclear Power Station Reactors No. 3, 4 and 5, which was previously submitted to NISA, Chubu Electric Power discovered analysis input data errors in six analyses in 15 places. Aside from input data errors, we also found descriptive errors in an additional 40 places as a result of transcription errors, etc.
We conducted analyses with correct data for those places having input data errors and found that while the content of some reports required amending, there was no impact on the seismic safety evaluation results for Hamaoka Nuclear Power Station Reactors No. 3, 4 and 5.
In consideration of the fact that input data errors have been found, Chubu Electric Power has analyzed the cause of the errors and has established recurrence prevention measures.
Chubu Electric Power takes this discovery of errors very seriously and going forward will faithfully implement these newly established recurrence prevention measures as we endeavor to prevent errors from happening.
*NISA instructions: "Concerning Re-Examination of Seismic Safety Evaluation Reports (Instructions)" (NISA No. 1; August 22, 2011) issued by NISA on August 22, 2011