THE NEW NEUTRON NOISE SOLVER OF THE MONTE CARLO CODE TRIPOLI-4?

摘要

Neutron noise appears as fluctuations of the neutron field induced by vibrations of fuel elements,control rods or any other mechanical structures in the core, as well as from globalor local fluctuations in the flow, density or void fraction of the coolant. Neutron noiseequations are obtained by assuming small perturbations of macroscopic cross-sectionsaround a steady-state neutron field and by subsequently taking the Fourier transform inthe frequency domain. Recently, a new Monte Carlo algorithm was proposed in order tosolve the transport equation in neutron noise theory with complex-valued weights and amodified collision operator. This paper presents the new neutron noise solver based onthese methods and implemented in the reference Monte Carlo code TRIPOLI-4R developedat CEA. We illustrate the capabilities of the solver by considering the noise analysisof a UOX PWR assembly.