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Title: High conduction neutron absorber to simulate fast reactor environment in an existing test reactor

A new metal matrix composite material has been developed to serve as a thermal neutron absorber for testing fast reactor fuels and materials in an existing pressurized water reactor. The performance of this material was evaluated by placing neutron fluence monitors within shrouded and unshrouded holders and irradiating for up to four cycles. The monitor wires were analyzed by gamma and X-ray spectrometry to determine the activities of the activation products. Adjusted neutron fluences were calculated and grouped into three bins—thermal, epithermal, and fast—to evaluate the spectral shift created by the new material. A comparison of shrouded and unshrouded fluence monitors shows a thermal fluence decrease of ~11 % for the shielded monitors. Radioisotope activity and mass for each of the major activation products is given to provide insight into the evolution of thermal absorption cross-section during irradiation. The thermal neutron absorption capability of the composite material appears to diminish at total neutron fluence levels of ~8 × 1025 n/m2. Calculated values for dpa in excess of 2.0 were obtained for two common structural materials (iron and nickel) of interest for future fast flux experiments.
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0236--5731
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Radioanalytical and Nuclear Chemistry; Journal Volume: 302; Journal Issue: 1
Research Org:
Idaho National Laboratory (INL)
Sponsoring Org:
Country of Publication:
United States
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; NEUTRON ABSORBERS; NEUTRON FLUENCE; NEUTRON FLUX fast reactor materials; Fast-to-thermal ratio; flux monitor; neutron absorber; neutron fluence; neutron flux