Estimation of the effects of self-shielding on multigroup reactor vessel fluence calculations
As American light water reactors age, a key limiting factor in plant lifetime is embrittlement of the pressure vessel because of high-energy neutron damage. Accurate estimation of the neutron fluence in the pressure vessel is thus critical for plant life extension. Deterministic and stochastic methodologies have been developed to calculate this fluence, to compare and benchmark with in-vessel and ex-vessel dosimetry, and to estimate uncertainties associated with the calculation. In the case of ex-vessel dosimetry, the calculation of the neutron flux in and through the pressure vessel becomes even more important. Comparisons between continuous energy Monte Carlo methods and multigroup deterministic methods reveal that the multigroup calculations consistently underestimate the Monte Carlo calculations in terms of neutron transport through the pressure vessel. Part of this underestimation may be attributed to inadequate accounting for energy self-shielding in the multigroup constants for the pressure vessel region.
- OSTI ID:
- 89226
- Report Number(s):
- CONF-941102--
- Journal Information:
- Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 71; ISSN 0003-018X; ISSN TANSAO
- Country of Publication:
- United States
- Language:
- English
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