EXPERIMENTAL AND COMPUTATIONAL STUDIES OF THE GAMMA-RAY ENERGY DEPOSITION RATE IN THE PURDUE FAST BREEDER BLANKET FACILITY (TLD, NEUTRON, TRANSPORT)
Abstract
The Purdue University Fast Breeder Blanket Facility (FBBF) is a source-driven facility which provides an absolute basis for calculation and experiment (C/E) comparisons. Experimental and computational studies of the gamma-ray energy deposition rate in the FBBF were performed to look for more improved experimental and computational methods. Measurements were made with thermoluminescent dosimeters (TLDs). Various corrections including the TLD neutron sensitivities and the f-factors (general cavity-ionization theory) were applied to the TLD measurements. Calculations were performed primarily with three computer codes--1DX, 2DB, and ANISN--and two nuclear libraries--LIB-IV and EPR. Both neutron and gamma-ray calculations were included. The previously reported deviations between the gamma-ray energy deposition C/E ratios for lead and for stainless steel were resolved by increasing the stainless steel sleeve thickness to attenuate the electrons produced in the surrounding field. The previous deviation between the gamma-ray energy deposition C/E ratios and the ('238)U capture C/E ratios were resolved by calculational improvements that conserved the gamma-ray energy yield. The C/E ratios for the gamma-ray energy deposition rate are close to unity in the inner part of the blanket and show increasing drop-off with increasing penetration into the blanket. It is believed that this C/E discrepancy comes primarily from the inaccuracies in the neutron part of the calculations, because similar drop-offs are also reported in the FBBF reaction rate C/E comparisons. Detailed analysis of the deviation between transport (S(,n )and diffusion calculations in the FBBF was performed. It was found that the deviation is built up in the blanket region and is largely independent of the curvature of the "independent" source region. Comparisons between S(,n) and diffusion calculations (on a one-dimensional basis) for neutron fluxes and reaction rates indicated that the use of transport calculations should reduce the discrepancies of C/E comparisons.
Degree
Ph.D.
Subject Area
Nuclear physics
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