ISSUES IN NEUTRON CROSS SECTION COVARIANCES

Mattoon, C.M. ; Oblozinsky,P.

Brookhaven National Laboratory

关键词: Fast Neutrons;    Cross Sections;    72 Physics Of Elementary Particles And Fields;    Quality Assurance;    Neutron Reactions;   

DOI  :  10.2172/1013490
RP-ID  :  BNL--93618-2010
RP-ID  :  DE-AC02-98CH10886
RP-ID  :  1013490

美国|英语

来源: UNT Digital Library

【 摘 要 】

We review neutron cross section covariances in both the resonance and fast neutron regions with the goal to identify existing issues in evaluation methods and their impact on covariances. We also outline ideas for suitable covariance quality assurance procedures.We show that the topic of covariance data remains controversial, the evaluation methodologies are not fully established and covariances produced by different approaches have unacceptable spread. The main controversy is in very low uncertainties generated by rigorous evaluation methods and much larger uncertainties based on simple estimates from experimental data. Since the evaluators tend to trust the former, while the users tend to trust the latter, this controversy has considerable practical implications. Dedicated effort is needed to arrive at covariance evaluation methods that would resolve this issue and produce results accepted internationally both by evaluators and users.