The Effects of Composition and Heat Treatment on Hardening and Embrittlement of Reactor Pressure Vessel Steels (NUREG/CR-6778)

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Publication Information

Manuscript Completed: April 2002
Date Published: May 2003

Prepared by:
G. R. Odette, G. E. Lucas, D. Klingensmith,
B. D. Wirth, D. Gragg

Department of Mechanical and Environmental Engineering
University of California at Santa Barbara
Santa Barbara, CA 93106

C. Santos, NRC Project Manager

NRC Job Code Y6396

Prepared for:
Division of Engineering Technology
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

This report addresses several important issues regarding possible revisions of RG 1.99 Rev. 2 to predict irradiation induced hardening (Δσ_y) and hence embrittlement manifested as shifts (ΔT) in the 41 J Charpy test transition temperature. We are developing a Δσ_y database from controlled, singlevariable experiments to map the individual and interactive effects of metallurgical and environmental variables. The data are generated from a large matrix of composition-controlled alloys irradiated in the Irradiation Variables Facility (IVAR) at the University of Michigan Ford Research Reactor. The results provide quantitative and independent validation of the two component form of the NUREG/CR-655 1 model, comprised of matrix feature (MF) and copper rich precipitate (CRP) terms. The IVAR database also quantitatively supports: 1) the model treatments of a strong copper-nickel interaction in the CRP term; 2) the treatment of phosphorous in the MF term; 3) an independent validation of a maximum effective matrix copper level (Cu_max) of around 0.3% following heat treatment; and 4) a sensitivity of Cu_max to nickel content. The IVAR database also shows: I) manganese interaction with copper and nickel in the CRP contribution; 2) manganese and nickel increase the MF term; 3) a somewhat unanticipated effect of flux and flux-composition interactions on the fluence dependence of Δσ_y and ΔT; and 4) a possible reduction in the effect of phosphorus at higher copper.