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Title: Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors. Final Report

This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermalization is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.
Authors:
 [1] ;  [2]
  1. North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1157573
Report Number(s):
DOE/NEUP--09-822
TRN: US1500394
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Research Org:
North Carolina State Univ., Raleigh, NC (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Programs (NEUP)
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; THERMAL NEUTRONS; TEMPERATURE RANGE 1000-4000 K; PEBBLE BED REACTORS; MODERATORS; THERMALIZATION; OPTIMIZATION; SCATTERING; NEUTRON TRANSPORT; COMPOSITE MATERIALS; RADIATION EFFECTS; IRRADIATION; HTGR TYPE REACTORS; NEUTRON REFLECTORS; BERYLLIUM CARBIDES; GRAPHITE