Effects of a Spectral Modifier on the Clinch River Breeder Reactor Low Level Flux Monitor Experiments Conducted in ZPPR-5

摘要

Current design of the Clinch River Breeder Reactor (CRBR) calls for the at-power flux monitors to be located outside the reactor vessel some 330 cm from the center of the core. This design uses these same detectors for the monitoring of refueling operations and the subsequent approach to power. Although adequate for at-power operation, these monitors could prove marginal in the shutdown mode (so called low level flux monitors). A series of experiments are to be performed on the CRBR engineering mockup (ZPPR-5) to test the ex-vessel monitors. The matrix design limits the distance from the core center to the detector position to approximately 200 cm. Hence, the full 330 cm from the core center to the LLFM can not be mocked up in the ZPPR-5 assembly. An attempt was made to design a spectral modifier which would result in the same source and absorber detector response as found in the CRBR design. This was accomplished using the source and adjoint fluxes obtained from a one-dimensional ANISN calculation. The results of examinations of several materials are presented. (ERA citation 01:023259)