On April 13, 2011, we received a directive document* "Collection of Reports Pursuant Article 67 Clause 1 of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors" from the Nuclear and Industrial Safety Agency (NISA) of the Ministry of Economy, Trade and Industry.
In accordance with the direction given, we investigated on the current seismic safety and reinforcement of Units 1 and 4 Reactor Buildings at Fukushima Daiichi Nuclear Power Station and submitted the results to NISA.
As debris removal from the upper part of Unit 4 Reactor Building was almost complete, the loading condition was reviewed and the design outline of the fuel handling machine structure to be installed in Unit 4 was determined accordingly. The seismic safety evaluation results taking into considerations these updates were submitted to NISA.
Since it was found that a part of the analysis data of Unit 4 Reactor Building included in the report was incorrect, correction was made and reanalysis was done while reviewing the entire data. We submitted a report addressing the cause of this issue and recurrence prevention measures to the Nuclear Regulation Authority.
(Previously announced on September 28, 2012)
This time, heat conduction analysis performed utilizing a more detailed model was newly included in the analysis parameters for seismic safety evaluation. The evaluation results have been submitted to the Nuclear Regulation Authority.
Attachment
Report on the Current Seismic Safety and Reinforcement of the Reactor Buildings at Fukushima Daiichi Nuclear Power Station (No.1) (Supplement) (Revision 2) (PDF 1.95MB)
Reference
"Submission of Report on the Current Seismic Safety and Reinforcement of the Reactor Buildings at Fukushima Daiichi Nuclear Power Station to the Nuclear Regulation Authority (No.1) (Supplement) (Revision 2) to the Nuclear Regulation Authority"(PDF 209KB)
* Directive document
"Collection of Reports Pursuant Article 67 Clause 1 of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors"