Publication Date:
2015-01-15
Description:
The 239 Pu fission chambers are widely used to measure fission spectrum neutron flux due to a flat response to fast neutrons. However, in the meantime the resonance and thermal neutrons can cause a significant influence on the measurement if they are moderated, which could be eliminated by using 10 B and Cd covers. At a column enriched uranium fast neutron critical assembly, the fission reaction rates of 239 Pu are measured as 1.791×10 −16 , 2.350×10 −16 and 1.385×10 −15 per second for 15 mm thick 10 B cover, 0.5 mm thick Cd cover, and no cover respectively, while the fission reaction rate of 239 Pu is rapidly increased to 2.569×10 −14 for a 20 mm thick polythene covering fission chamber. The average 239 Pu fission cross-section of thermal and resonance neutrons is calculated to be 500 b and 24.95 b with the assumption of 1/ v and 1/ E spectra respectively, then thermal...
Print ISSN:
1674-1137
Topics:
Physics
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