Published: Jan 2000
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The results of Charpy V-notch impact tests for A302B and A533B-1 Correlation Monitor Materials (CMM) listed in the surveillance power reactor database (PR-EDB) and material test reactor database (TR-EDB) are analyzed. The shift of the transition temperature at 30 ft-lb (T30) is considered as the primary measure of radiation embrittlement in this paper. The hyperbolic tangent fitting model and uncertainty of the fitting parameters for Charpy impact tests are presented. For the surveillance CMM data, the transition temperature shifts at 30 ft-lb (ΔT30) generally follow the predictions provided by Regulatory Guide 1.99, Revision 2, (R.G. 1.99/2) and draft E900-98. Difference in capsule temperatures is a likely explanation for large deviations from R.G. 1.99/2 and ASTM E900-98. Deviations from the R.G. 1.99/2 predictions are correlated to similar deviations for the accompanying materials in the same capsules, but large random fluctuations prevent precise quantitative determination. Significant scatter is noted in the surveillance data. The major contributions to the uncertainty of the prediction models, and the overall data scatter, are from mechanical test results, chemical analysis, difference in effective copper content resulting from the different post weld heat treatment, irradiation environments, fluence evaluation, and inhomogeneous material properties. Thus the prediction model can be improved if the above- mentioned error sources are controlled. In general, the embrittlement behavior of both the A302B and A533B-1 plate materials is similar. There is evidence for a flux effect in the CMM data irradiated in test reactors; thus its implication for power reactor surveillance programs deserves special attention.
radiation embrittlement, power reactor, database, LWR, reference materials
Research Scientist, Oak Ridge National Laboratory, Oak Ridge, TN