STRESS CORROSION CRACKING OF PRESSURE VESSEL STEELS IN HOT WATER, AND SAFETY MARGINS AGAINST INSERVICE CRACKING

1989 ◽  
pp. 1595-1605
Author(s):  
M.O. Speidel ◽  
R.M. Magdowski
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pressure Vessel ◽  
Corrosion Cracking ◽  
Hot Water ◽  
Safety Margins ◽  
Pressure Vessel Steels

Weld Residual Stresses and Primary Water Stress Corrosion Cracking in Bimetal Nuclear Pipe Welds

2007 ◽  
Author(s):  
Frederick W. Brust ◽  
Paul M. Scott
Keyword(s):  
Water Stress ◽  
Residual Stresses ◽  
Weld Metal ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Pressure Vessel ◽  
Large Diameter ◽  
Corrosion Cracking ◽  
Primary Water

There have been incidents recently where cracking has been observed in the bi-metallic welds that join the hot leg to the reactor pressure vessel nozzle. The hot leg pipes are typically large diameter, thick wall pipes. Typically, an inconel weld metal is used to join the ferritic pressure vessel steel to the stainless steel pipe. The cracking, mainly confined to the inconel weld metal, is caused by corrosion mechanisms. Tensile weld residual stresses, in addition to service loads, contribute to PWSCC (Primary Water Stress Corrosion Cracking) crack growth. In addition to the large diameter hot leg pipe, cracking in other piping components of different sizes has been observed. For instance, surge lines and spray line cracking has been observed that has been attributed to this degradation mechanism. Here we present some models which are used to predict the PWSCC behavior in nuclear piping. This includes weld model solutions of bimetal pipe welds along with an example calculation of PWSCC crack growth in a hot leg. Risk based considerations are also discussed.

Effects of H2 Additions on Stress Corrosion Cracking in a Boiling Water Reactor

CORROSION ◽  
1985 ◽  
Vol 41 (1) ◽  
pp. 19-30 ◽  
Author(s):  
M. E. Indig ◽  
J. E. Weber
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pressure Vessel ◽  
Corrosion Cracking ◽  
304 Stainless Steel ◽  
Pressure Vessel Steel ◽  
Aisi 304 Stainless Steel ◽  
Vessel Steel ◽  
Aisi 304

Abstract Controlled amounts of hydrogen were injected into the Dresden-2 boiling water reactor (BWR) during a five week period. The effect of the hydrogen modifed water chemistry on major structural alloys used in the BWR system was studied. The studies were conducted in a test facility consisting of two 1 L vessels which were piped to receive reactor water from the discharge side of the main recirculation pump. One of the vessels was used to measure electrochemical potentials. The second vessel was used to perform slow strain rate stress corrosion cracking tests. Electrochemical measurements were conducted continuously during normal BWR operation and during periods of hydrogen injection. The hydrogen injection caused the quantity of dissolved oxygen to decrease, which resulted in a substantial drop in corrosion potentials. At the highest injection rate, the corrosion potential of AISI 304 stainless steel dropped below the potential at which intergranular stress corrosion cracking (IGSCC) could be expected. Stress corrosion tests were conducted on severely sensitized AISI 304 stainless steel and pressure vessel steel. During normal operation, the stainless steel failed primarily by IGSCC. During H2 injection when the water contained <20 ppm O2, both IGSCC of the stainless steel and transgranular SCC of pressure vessel steel were eliminated.

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