TOKYO ELECTRIC POWER COMPANY HOLDINGS, INC. 
By Press Release (Dec 12,2012)
Bent Fuel Assembly Water Rod at Unit 5 of Kashiwazaki-Kariwa Nuclear Power Station (Follow-up Report)
We are currently investigating the bent found on part of spent fuel assembly water rod*1 while inspecting the upper part (clip) of fuel assembly channel box*2 at Unit 5 of Kashiwazaki-Kariwa Nuclear Power Station under regular inspection. As a result of appearance inspection, the water rods of 18 out of 65 spent fuel assemblies were found to be bent.
The 2 out of these 18 spent fuel assemblies on which major bent was found were inspected further utilizing a fiberscope. As a result of inspection, the following has been found.
- Deformation was found near the hole on the thin area in the lower part of water rod where strength is relatively low.
- Though some holes have become smaller due to deformation, no hole was completely closed.
- The fuel rods adjacent to the bent water rods were touching or close to one another.
As fuel rods were found to be touching one another due to the bent water rods, it has been judged by the Nuclear Regulatory Agency that the incident applies to Article 19-17, Paragraph 1, Item 3*3 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors).
Based on the inspection results, we will continue investigating the cause of the bent water rod and report the results to the Nuclear Regulation Authority.
Attachment
"Fuel assembly inspection in response to the bent water rod found at Unit 5 of Kashiwazaki-Kariwa Nuclear Power Station"
The 2 out of these 18 spent fuel assemblies on which major bent was found were inspected further utilizing a fiberscope. As a result of inspection, the following has been found.
- Deformation was found near the hole on the thin area in the lower part of water rod where strength is relatively low.
- Though some holes have become smaller due to deformation, no hole was completely closed.
- The fuel rods adjacent to the bent water rods were touching or close to one another.
As fuel rods were found to be touching one another due to the bent water rods, it has been judged by the Nuclear Regulatory Agency that the incident applies to Article 19-17, Paragraph 1, Item 3*3 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors).
Based on the inspection results, we will continue investigating the cause of the bent water rod and report the results to the Nuclear Regulation Authority.
Attachment
"Fuel assembly inspection in response to the bent water rod found at Unit 5 of Kashiwazaki-Kariwa Nuclear Power Station"
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