DEVELOPMENT AND APPLICATION OF THE REGIONAL ANGULAR REFINEMENT TECHNIQUE AND ITS APPLICATION TO NON-CONVENTIONAL PROBLEMS

We have investigated new quadrature sets for the solution of the Boltzmann transport equation for non-conventional problems. For problems where the angular flux and/or source are highly peaked, it is necessary to utilize a high order quadrature set. Moreover, if the physical system contains large regions of low density or highly absorbent materials, the ray-effects will appear in the flux distribution. In these circumstances the Level Symmetric quadrature set is not suitable, because of its limitation to order S20. We discussed in a previous paper these limitations and we developed new quadrature techniques including the EW, PN-EW and PN-TN with a new biasing approach called Ordinate Splitting (OS). In this paper we derive a new biasing technique, called Regional Angular Refinement (RAR). The discrete directions generated with the RAR technique satisfy the moments of direction cosines of transport equation. We have simulated a CT-Scan device using these new quadrature techniques and benchmarked the results. In this paper we present a new biasing technique called Regional Angular Refinement (RAR). This methodology has been utilized for simulating a CT-Scan device used for medical/industrial applications. A CT-Scan device utilizes a collimated X-ray source (fan-beam) to scan an object or a patient 1 . We utilized the new quadrature sets generated with the RAR technique to simulate a CTScan model. The SN method is extensively used to solve the neutron transport equation. The angular variable in the transport equation is discretized into a finite number of directions, with the associated weights. 3 The