At around 11:07 AM on September 22, during debris removal from the upper part of Unit 3 Reactor Building, a steel beam (approx. 300mmx200mmx7m, approx. 470kg) which had been on the side of the spent fuel pool (SFP) and found to be unstable slipped and fell into the pool when a worker was trying to grab it using an oil-pressure fork attached to the head of a crane.
Regarding this incident, we received a directive document*1 "A steel beam falling into Unit 3 spent fuel pool at Fukushima Daiichi Nuclear Power Station (Direction)" from the Nuclear Regulation Authority on September 26. In response to the direction, we evaluated the impact of this incident on the soundness of the spent fuel, the spent fuel storage rack and the spent fuel pool while investigating the cause of this matter and discussing recurrence prevention measures. On October 3, a report was submitted to the Nuclear Regulation Authority.
On October 10, we received another directive document*2 "A steel beam falling into Unit 3 spent fuel pool at Fukushima Daiichi Nuclear Power Station (Additional Direction)" from the Nuclear Regulation Authority.
(Previously announced on September 26, October 3 and 11, 2012)
In accordance with the direction given, we have put together the attached report on the following points and submitted it to the Nuclear Regulation Authority today.
- Plan to investigate the debris condition to implement during the debris removal at Unit 3 spent fuel pool in collaboration with cooperative companies.
- Method to directly investigate the condition of spent fuel in the event that debris such as a steel beam falls into the spent fuel pool.
- Soundness evaluation of spent fuel and impact analysis in the case that the cooling water for the spent fuel pool is lost.
Attachment
"Additional Report on the Steel Beam Falling into Unit 3 Spent Fuel Pool at Fukushima Daiichi Nuclear Power Station" (PDF 343KB)
*1 Directive document
"A steel beam falling into Unit 3 spent fuel pool at Fukushima Daiichi Nuclear Power Station (Direction)"
*2 Directive document
"A steel beam falling into Unit 3 spent fuel pool at Fukushima Daiichi Nuclear Power Station (Additional Direction)"
The aforementioned documents are available only in Japanese. We apologize for the inconvenience this may cause.
