SEDL / STP / STP956-EB / STP25672S

Damage Rate and Spectrum Effects in Ferritic Steel ΔNDTT Data

Simons, RL
Senior scientist, Hanford Engineering Development Laboratory, Richland, WA

Pages: 17    Published: Jan 1987

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Abstract

A model was developed for irradiation-induced hardening in pressure vessel steels by cascade-induced nucleation and free defect diffusion of copper to coherent copper clusters. The model was used as a functional framework for fitting data on macroscopic property change (ΔNDTT) as a function of damage dose and dose rate. Several defect cross sections having different neutron energy dependences were tried. The cross section for Frenkel pair production, based on resistivity measurements at 4 K, was found to give a comparable or slightly better fit to the data than dpa. Damage rate is an important parameter to consider in correlation of ΔNDTT data, and damage rate can affect the nucleation as well as the growth of the copper precipitation.