Effect of solid solution carbon on stress corrosion cracking of Alloy 600 in a primary water at 360°C

2014 ◽  
Vol 603 ◽  
pp. 129-133 ◽  
Author(s):  
Do Haeng Hur ◽  
Deok Hyun Lee
Author(s):  
Charles R. Frye ◽  
Melvin L. Arey ◽  
Michael R. Robinson ◽  
David E. Whitaker

In February 2001, a routine visual inspection of the reactor vessel head of Oconee Nuclear Station Unit 3 identified boric acid crystals at nine of sixty-nine locations where control rod drive mechanism housings (CRDM nozzles) penetrate the head. The boric acid deposits resulted from primary coolant leaking from cracks in the nozzle attachment weld and from through-thickness cracks in the nozzle wall. A general overview of the inspection and repair process is presented and results of the metallurgical analysis are discussed in more detail. The analysis confirmed that primary water stress corrosion cracking (PWSCC) is the mechanism of failure of both the Alloy 182 weld filler material and the alloy 600 wrought base material.


Author(s):  
Naoki Chigusa ◽  
Shinro Hirano ◽  
Takehiko Sera ◽  
Hitoshi Kaguchi ◽  
Masayuki Mukai ◽  
...  

Several Japanese PWR power plants have experienced Primary Water Stress Corrosion Cracking (PWSCC) on dissimilar weld joints since 2004. J weld of 3 Reactor Vessel Head Penetration in Ohi unit 3 is one of the PWSCC incidents occurred in 2004 and has been studied by sampling and opening the fracture surface after its repair. Including Ohi unit 3 Reactor Vessel Head Penetration repair, Japanese PWR utilities and MHI have been developing the preventive maintenance and repair technologies applicable to alloy 600 welds and base metal, following PWSCC events on the Bugey-3 and V.C. Summer. This paper describes recent Japanese PWSCC incidents and repair technologies developed in Japan.


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