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

这个NSERC/DG提案的目的是开放晶格码Dragon 5，以表征原子水平上的光子和电子输运。这些发展的预期成果将有利于加拿大两个重要的研究领域：1。改进Dragon 5精确表示核反应堆中伽马加热现象的能力。这一能力大大提高了Dragon 5作为2030-2060年CANDU应用的未来国际标准工具集（IST）点阵代码的地位。全面的核反应堆，如CANDU，是减少温室效应和我们对化石燃料长期依赖的最重要选择。核能的特点是寿命期内温室气体排放量极低，容量系数极高。2.将基于光子-电子耦合玻尔兹曼输运方程（BTE）的模型与专用硬件相结合，导致更准确的剂量计算和改进的放射肿瘤学中的放射治疗计划（RTP）。目前使用的RTP技术都存在一个问题，即速度慢或不准确，这使得它们在临床上的使用不是最佳的。我们计划开发一种新的RTP算法，结合速度和准确性。使这样的算法可用将通过使得当患者躺在治疗台上时能够真实的计算剂量而彻底改变放射治疗领域。这些成果需要在四个具体的子项目上取得进展：D.1为耦合力学统计产生一致的原子和核数据将扩展横截面处理能力，以便将与二次电子和光子有关的原子数据处理成多群数据。其他感兴趣的量将产生：动量传递截面和阻止本领。在Dragon 5水平，将计算吸收剂量和能量沉积。D.2基于中子-电子-光子耦合BTE-BFP的Dragon 5模型目前基于中子BTE的解。电子输运用Boltzmann-Fokker-Plank（BFP）方程描述，其中粒子散射被假设为高度前向峰值，并且可以使用泰勒展开技术用偏微分算子近似。D.3燃料单元电池或组件中的伽马输运根据光子BTE，裂变、辐射俘获或放射性衰变产生的能量的一部分通过光子传输。在某些情况下，初级光子导致电子的释放和次级光子的产生。D.4放射治疗中耦合BTE-BFP的确定性解第二个应用领域是放射治疗。在RTP中使用电离辐射。基于BTE-BFP的放射治疗模型由两个耦合方程组成，用于描述光子和电子的输运。使用基于耦合的模型的确定性解为扰动和灵敏度计算开辟了道路。

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.