Back to 2006 listInformation about Cracks Found in Hafnium Control Rod in Hamaoka Nuclear Power Station No. 3
August 7, 2006
Chubu Electric Power Co., Inc.
In accordance with instructions* issued by the Nuclear and Industrial Safety Agency, external checks on thirteen used hafnium control rods (thermal neutron irradiance level approx 7.1 x 10 to the power of 21st/cm2)are being carried out as part of a regular inspection on Hamaoka Nuclear Power Station No. 3 (boiling water reactor, rated electric output 1.1 million kW). Cracks have been discovered in the sheath and tie rod sections of the one rod which as been inspected so far.
It appears that these cracks are the same as others found in hafnium control rods in both the Chubu Electric Power Company and other companies, the causes of which have already been investigated.
All remaining control rods will be investigated, and the results of these investigations will be announced in full.
All thirteen hafnium control rods removed from the nuclear reactor are to be replaced with boron carbide control rods.
These inspections will have no effect on outside radioactivity.
*These instructions were issued by the Nuclear and Industrial Safety Agency on January 19, 2006 after cracks were found in hafnium control rods in the Tokyo Electric Power Company's Fukushima Power Station No. 1. All companies running boiling water reactors were instructed to inspect all hafnium control rods.
(Attachment)
Station No 3 - Inspection of Hafnium Control Roads
Note:The blue and red spots in the photographs are the result of camera noise caused by radiation
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