Irradiation effects on Charpy impact and tensile properties of low upper-shelf welds, HSSI series 2 and 3

Technical Report · Thu Aug 01 00:00:00 EDT 1991

OSTI ID:5289281

Nanstad, R K; Berggren, R G ^[1]

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1. Oak Ridge National Lab., TN (United States)

When reactor pressure vessel steels exhibit Charpy V-notch impact upper-shelf energy levels of less than 68 J (50 ft-lb), the requirements of Title 10, Code of Federal Regulations, Part 50, Appendix G, are not met. The regulations require, as an option, that a fracture mechanics analysis be performed that conservatively demonstrates adequate safety margins for continued operation. Under conditions where large prefracture crack-tip plastic zones are present, linear-elastic fracture mechanics concepts are not applicable, and the use of elastic-plastic fracture mechanics concepts has been recommended by the US Nuclear Regulatory Commission. A number of Babcock and Wilcox Company-fabricated reactor vessels in commercial pressurized water reactor plants include welds with both relatively low initial Charpy upper-shelf energies and high copper concentrations, which make them highly sensitive to neutron irradiation. As a result, the Charpy upper-shelf energies of many welds are expected to fall below 68 J (50 ft-lb) prior to reaching design life. The Heavy-Section Steel Irradiation Program conducted the Second and Third Irradiation Series to investigate the effects of irradiation on the ductile fracture toughness of seven commercially fabricated, low upper-shelf welds. This report represents analyses of the Charpy impact and tensile test data, including adjustments for irradiation temperature and fluence normalization, which make possible comparison of the irradiation sensitivity the different welds.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering; Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USNRC; Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5289281
• Report Number(s): NUREG/CR-5696; ORNL/TM-11804; ON: TI91018983
• Country of Publication: United States
• Language: English

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