Determination of the neutron and gamma flux distribution in the pressure vessel and cavity of a boiling water reactor

Abstract

The Grand Gulf Boiling Water Reactor (BWR/6), owned and operated by Mississippi Power Light Company has been analyzed to determine the neutron and gamma energy spectrum and flux levels in regions from the reactor vessel throughout the concrete shield wall. Several two-dimensional and one-dimensional transport calculations were performed for the Grand Gulf reactor configuration. The results from these transport calculations indicate the flux above 1 MeV peaks near the axial midplane and azimuthal angle between 40{degree} and 45{degree}, depending on the radial locations. The peak flux above 1 MeV incident on the vessel and at midcavity is about 1.82 {times} 10{sup 9} and 1.07 {times} 10{sup 8} n{center dot}cm{sup {minus}2}{center dot}s{sup {minus}1}, respectively. The vessel fluence accumulated during Cycle 2 and after 32 effective full power years is about 4.41 {times} 10{sup 16} and 1.84 {times} 10{sup 18} n{center dot}cm{sup {minus}2}{center dot}s{sup {minus}1}, respectively. The peak flux above 1 MeV at the front of the concrete shield wall, 15.24 cm (6 in.) into the concrete wall, and 30.48 cm (1 ft) into the concrete wall is about 7.91 {times} 10{sup 7}, 7.24 {times} 10{sup 6}, and 6.44 {times} 10{sup 5} n{center dot}cm{sup {minus}2}{center dot}s{sup {minus}1}, respectively. The results obtained frommore » the gamma calculations show that the peak gamma heating at the 0-T location of the reactor pressure vessel has a value of 2.54 {times} 10{sup {minus}3} W/g of stainless steel (SS 304). The peak gamma absorbed dose rate at the midcavity is about 7.31 {times} 10{sup 3} rad/h at full power operation. 7 refs., 34 figs., 23 tabs.« less