An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations

Conference · Tue Jun 16 04:00:00 EDT 1998

OSTI ID:9122

Stoller, R E ^[1]; Greenwood, L R

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1. ORNL

The results of molecular dynamics (MD) displacement cascade simulations in bcc iron have been used to obtain effective cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the displacements calculated using the standard secondary displacement model of Norgett, Robinson, and Torrens (NRT), and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. Primary knockon atom spectra for iron obtained from the SPECTER code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and materials test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various enviromnents do not lead to significant differences between the average primary damage formation parameters. In particular, the defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. The variation of the defect production cross sections as a function of depth into the reactor pressure vessel wall is used as a sample application of the cross sections. A slight difference between the attenuation behavior of the PWR and BWR was noted; this difference could be explained by a subtle difference in the energy dependence of the neutron spectra. Overall, the simulations support the continued use of dpa as a damage correlation parameter.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
• Sponsoring Organization: USNRC Office of Nuclear Regulatory Research; USDOE Office of Science
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 9122
• Report Number(s): ORNL/CP-103988; KC 02 01 04 0; 41 W6 95 3W 1; ON: DE00009122
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
Ferritic Steels
Point Defects
Pressure Vessels
ferritic steels
modeling
molecular dynamics
point defects
pressure vessels
radiation damage
rate theory