Isotropic analogs for radiation levels across off-core midplane penetrations

This paper develops the isotropic analogs of fast neutron flux (energy > 1 MeV) and gamma dose rate at the core mid-plane and at a typical off-core midplane penetration, e.g., a recirculation line penetration. The authors use the basic methodology of evaluating radiation levels outside primary shield wall penetrations using isotropic analogs previously developed. The method developed and illustrated in this paper consists of combining one-dimensional transport analysis, e.g., ANISND, with experimental studies of variations in fast neutron flux and gamma dose rate for BWRs and simple penetration formulas generally available in textbooks. The application of this approach to pressurized water reactors is straightforward. As the analysis for core midplane and recirculation line penetrations presented here illustrates, the results of simplified analyses become increasingly conservative as the offset of penetration axis from core midplane increases