Measurement and Analysis of Gamma Ray Induced Contamination of Neutron Dosimetry Procedures Used for Reactor Pressure Vessel Applications. Final Report.

摘要

Science Applications,Incorporated (SAI) has performed measurements and calculations to assess the effect of photon induced activity in neutron spectra measuremes for pressure vessel dosimetry. Such measurement contamination would lead to an overestimate of the neutron flux incident on the pressure vessel,and,hence,an underestimate of the pressure vessel lifetime. Measurements were performed using the pool-type reactor at the University of Virginia at Charlottesville (UVA). Threshold dosimetry foils were used in conjunction with a photofraction gauge to measure neutron spectra and the fraction of activity in the foils due to gamma rays at various distances from the core. One-dimensional calculations were performed to theoretically predict the measured data and good agreement was found. Several methods for correcting measured neutron spectra for photocontamination are presented and applied to UVA reactor measurements. (ERA citation 04:044753)