Application of Boltzmann Transport Equation solutions to nuclear reactor physics and radiotherapy applications

点击翻译按钮获取中文摘要

The aim of this NSERC/DG proposal is to open the lattice code Dragon5 to the characterization of photon and electron transport at the atomic level. Anticipated outcomes of these developments will benefit to two important research fields in Canada: 1. Improvement of the capability of Dragon5 to accurately represent the gamma heating phenomena in nuclear reactors. This capability greatly improves the position of Dragon5 as the future International Standard Toolset (IST) lattice code for CANDU applications in the 2030-2060 time frame. Full-scale nuclear reactors such as CANDUs represent the most serious option to reduce both greenhouse effect and our dependency on fossil fuels on the long term. Nuclear energy is characterized by extremely low lifetime greenhouse gas emission and very high capacity factor. 2. Combining a photon-electron coupled Boltzmann transport equation (BTE) based model with dedicated hardware leads to more accurate dose calculations and improved radiation treatment planning (RTP) in radio-oncology. RTP technologies currently in use all suffer from one problem, be it slowness or inaccuracy, that makes their use suboptimal in the clinic. We plan to develop a new RTP algorithm that combines speed and accuracy. Making such an algorithm available will revolutionize the field of radiotherapy by making it possible to calculate the dose in real time while the patient is lying on the treatment table. These outcomes require advances on four specific sub-projects: D.1 Producing consistent atomic and nuclear data for coupled mechanical statistics Cross section processing capabilities will be extended so as to process the atomic data related to secondary electrons and photons into multigroup data. Other quantities of interest will be generated: the momentum transfer cross section and the stopping power. At the Dragon5 level, the absorbed dose and energy deposition will be computed. D.2 Neutron-electron-photon coupled BTE-BFP based model Dragon5 is presently based on a solution of the BTE for neutrons. Electron transport is described with the Boltzmann-Fokker-Plank (BFP) equation where the particle scattering is assumed to be highly forward peaked and can be approximated with a partial differential operator using Taylor expansion techniques. D.3 Gamma transport in a fuel unit cell or assembly A fraction of the energy produced by fission, radiative capture or radioactive decay is transported by photons, according to a photonic BTE. In some cases, a primary photon causes the releases of an electron and the production of a secondary photon. D.4 Deterministic solution of the coupled BTE-BFP in radiotherapy The second domain of applications is the radiotherapy. Ionizing radiation is used in RTP. The BTE-BFP based model in radiotherapy consists of two coupled equations to describe photon and electron transport. Using a deterministic solution of the coupled based model open the way to perturbation and sensitivity calculations.