20 Jul (NucNet): Japan’s Nuclear Safety Commission (NSC) has said back-checks using revised seismic standards are already under way at the earthquake-hit Kashiwazaki Kariwa nuclear power plant in west-coast Niigata prefecture.
But commission chairman Atsuyuki Suzuki has called on regulator the Nuclear and Industrial Safety Agency to tell plant operator Tokyo Electric Power Company (Tepco) to bring forward checks at the plant because “it will be the best way to answer the nation’s seismic safety concerns”.
Japan’s regulatory guide for reviewing the seismic design of nuclear power facilities was revised in September 2006 and back-checks on the country’s plants have begun using the so-called New Guide.
Back-checks at Kashiwazaki Kariwa are scheduled to be completed by December 2008, the NSC said in a statement.
Meanwhile, the Japan Meteorological Agency says it is possible the fault which caused Monday’s earthquake may run underneath the Kashiwazaki Kariwa plant. The NSC has asked Tepco to carry out an immediate investigation into the agency’s claims.
“The earthquake caused very strong ground motion,” said Mr Suzuki. “Nevertheless, the nuclear reactors in operating mode were shut down under control. The most significant safety measures functioned, as intended in the design… consequently the nuclear plant safety was maintained and this indicates the basic appropriateness of seismic regulations.”
However, the NSC said it is “crucially important” to evaluate in detail, in line with the New Guide, the appropriateness of the assumptions in the original design.
Tepco says it has now collected seismic data from 97 seismographs for all seven units at the Kashiwazaki Kariwa plant, adding to data published earlier this week for units 1, 5 and 6. For more information see the English section of Tepco’s website (www.tepco.co.jp).
>>Related reports in the NucNet database (available to subscribers)
No Environmental Impact As 3 Units Shut Down In Japan Earthquake (News No. 168, 17 July 2007)
Tepco Releases Preliminary Seismic Data For Earthquake N-Plant (News No. 170, 18 July 2007)
Governor Calls For Seismic Review Of Japan Nuclear Plants (News No. 172, 19 July 2007)
