One-Dimensional, Time-Dependent, Integral Neutron Transport For Inertial Confinement Fusion.

摘要

Neutron transport is of great importance to inertial confinement fusion (ICF) for several reasons. An accurate neutron energy spectrum is necessary for tritium breeding purposes, and the deposition of energy in the ICF target by energetic neutrons born from fusion may have detrimental effects on the fusion burn. The goal of this research was to develop an accurate neutron transport method that can be incorporated into an existing radiation-hydrodynamics code for modeling ICF implosions.;A novel time-dependent neutron transport method, based on the integral form of the neutron transport equation, was developed. This method utilizes a dimensionless integration space and the Neumann series method to obtain the integral form of the reduced collisions equations.;This neutron transport method was implemented for infinite slab and sphere geometries. Using a pulsed source in space and time, the method was used to reproduce benchmark solutions previously published in the literature, and was found to have excellent agreement with these benchmarks.;The method was expanded to incorporate finite slab and sphere geometries. The method was implemented for a finite slab, and benchmarked against PARTISN, a finite difference, discrete-ordinates code. The method was found to agree with PARTISN at intermediate mean free times, while diverging from PARTISN at late mean free times. The method was used to obtain analytic expression for the first two collided fluxes in a finite sphere geometry. A collision study was performed for both geometries to determine how many collisions were necessary to approximate the total flux at early mean free times. This study showed that only a few collisions were necessary to approximate the total flux at times of interest to ICF applications.