A DIRECT INTEGRATION MULTIPLE COLLISION INTEGRAL TRANSPORT ANALYSIS METHOD FOR HIGH ENERGY FUSION NEUTRONICS (SCATTERING KINEMATICS, RADIATION)
Abstract
The neutronics analysis of a fusion reactor is an important part of the overall system design. However, this analysis is significantly complicated by the inherent difficulties of long mean free path lengths, highly forward biased scattering, and localized 14.1MeV fusion neutron source; these complications give rise to a large solution component that can be viewed as "streaming" through the system. In addition, typical fusion neutronics calculations use analysis methods developed for other nuclear technologies and difficulties exist when these methods are extended to fusion neutronics; the agreement of calculated and measured neutronics parameters for fusion neutronics experiments is inconsistent. A new analysis method that is specially suited for the inherent difficulties of fusion neutronics was developed to provide detailed studies of the fusion neutron transport physics. These studies should provide a better understanding of the limitations and accuracies of typical fusion neutronics calculations. The new analysis method is based on the direct integration of the integral form of the neutron transport equation and employs a continuous energy formulation with the exact treatment of the energy-angle kinematics of the scattering process. In addition, the overall solution is analyzed in terms of uncollided, once collided, and multi-collided solution components based on a multiple collision treatment. Furthermore, the numerical evaluations of integrals use quadrature schemes that are based on the actual dependencies exhibited in the integrands. The new DITRAN computer code was developed on the Cyber 205 vector supercomputer to implement this direct integration multiple collision fusion neutronics analysis. Three representative fusion reactor models were devised and the solutions to these problems were studied to provide suitable choices for the numerical quadrature orders as well as the discretized solution grid and to understand the limitations of the new analysis method. As further verification and as a first step in assessing the accuracy of existing fusion neutronics calculations, solutions obtained using the new analysis method were compared to typical multigroup discrete ordinates calculations.
Degree
Ph.D.
Subject Area
Nuclear physics
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