Effect of the fission spectra changes on pressure-vessel flux determination
The impact is discussed of the differences in fission spectra from the SAILOR and BUGLE-96 cross-section libraries on reactor pressure vessel (RPV) flux determination. The fission spectra from the SAILOR library (ENDF/B-IV) and BUGLE-96 library (ENDF/B-VI) are compared. The SAILOR {sup 239}Pu spectrum was collapsed from the VITAMIN-C library, which was the basis for SAILOR. The high-energy parts of the spectra (above {approximately}3 MeV) are much higher in SAILOR than in BUGLE-96. To assess the effect of these differences, a series of transport calculations of the H.B. Robinson Unit 2 pressurized water reactor were performed with the DORT code. The combined fission spectrum was taken as 0.5 x {chi} ({sup 235}U) + 0.5 x {chi} ({sup 239}Pu). The calculations with SAILOR cross sections were done with the combined fission spectrum from SAILOR and BUGLE-96. The spectra in the surveillance capsule and in the cavity from the two calculations are compared. The differences in fission spectra are readily transported to the out-of-core locations. While group fluxes at 20 MeV differ by a factor of 2, the fast fluxes (E {gt} 1 MeV) from the two calculations agree within 3 to 4% in the capsule, inside the RPV, and in the cavity. Equivalent calculations with BUGLE-96 produced similar results. The calculated reaction rates are compared with the measurements. The calculations with the SAILOR fission spectra give higher average calculated-to-measured (C/M) ratios both in the capsule and in the cavity, and with both the SAILOR and BUGLE-96 cross sections. However, the C/M ratios obtained with the SAILOR fission spectra show systematic increases from lower to higher threshold dosimeters (left to right in Table 1) and larger variations of the C/M ratios. Both effects are more pronounced in the cavity.
- Research Organization:
- Oak Ridge National Lab., TN (US)
- OSTI ID:
- 20005834
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 81; Conference: American Nuclear Society 1999 Winter Meeting, Long Beach, CA (US), 11/14/1999--11/18/1999; Other Information: PBD: 1999; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
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