Feasibility of reactivity measurement with noise analysis for small PWR Core

Abstract

In this thesis, feasibility of reactivity estimation with a noise analysis for a small pressurized water reactor (PWR) is studied. Estimation of reactivity with noise analysis can be beneficial in terms of nuclear reactor system monitoring by taking advantage of naturally occurring fluctuation. Consequently, safety of nuclear power plant can be improved. First of all, the essential principles of noise analysis is discussed for the reactivity measurement. Among several noise analysis methods, the Feynman-$\alpha$ method is chosen to estimate reactivity of a small PWR in this study. The Monte Carlo code MCNP6 is used to model the PWR core and ex-core detector signals, and Matlab is used for the data processing based on the Feynman-$\alpha$ method. To improve the detector efficiency, special ex-core detectors were considered in addition to the conventional ones. In this work, both BF3 and He-3 gas are used for the neutron absorber material for the detectors.