Monte Carlo Studies Indicating That Least Squares Is a Biased Estimator for the Charpy Shift Fluence Exponent

摘要

The LWR Pressure Vessel Dosimetry Program is committed to the writing of ASTM standards relating irradiation induced embrittlement of pressure vessel steel and the relevant parameters associated with the exposurethat produce embrittlement. These relevant parameters include the fluence, spectral shape, flux, irradiation temperature, and the chemistry, microstructure, and prior thermo-mechanical history of the steel being irradiated. The ultimate aim is to obtain analytic relations between the parameters and variables involved. The successful accomplishment of this task will require analysis of existing available data relating the embrittlement and the relevant parameters. The present report has the objective of analyzing the existing data base to ascertain the extent to which statistical scatter in the analytical relations can be reduced by the elimination of errors in the fluence calculations of previously reported experiments.