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

玻尔兹曼输运方程解在核反应堆物理和放射治疗应用中的应用

• 批准号: RGPIN-2021-03899
• 负责人: Hébert, Alain
• 金额: $ 1.75万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741837
• 关键词: Application; Boltzmann; Transport; Equation; solutions

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.

NSERC/DG 提案的目的是开放晶格代码 Dragon5，以在原子水平上表征光子和电子传输。这些发展的预期成果将有利于加拿大的两个重要研究领域： 1. 提高 Dragon5 准确表示核反应堆中伽马加热现象的能力。这一功能极大地提高了 Dragon5 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。 CANDU 等全尺寸核反应堆是减少温室效应和长期对化石燃料依赖的最严肃的选择。核能的特点是生命周期温室气体排放量极低，容量系数非常高。 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，可以实现更准确的剂量计算并改进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，无论是速度慢还是不准确，这使得它们在临床上的使用效果不佳。我们计划开发一种兼具速度和准确性的新 RTP 算法。提供这样的算法将彻底改变放射治疗领域，使患者躺在治疗台上时实时计算剂量成为可能。这些成果需要在四个具体子项目上取得进展： D.1 为耦合机械统计产生一致的原子和核数据 将扩展截面处理能力，以便将与二次电子和光子相关的原子数据处理成多组数据。将生成其他感兴趣的量：动量传递截面和阻止本领。在 Dragon5 级别，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 的模型 Dragon5 目前基于中子 BTE 的解决方案。电子传输用玻尔兹曼-福克-普朗克 (BFP) 方程描述，其中假定粒子散射具有高前向峰值，并且可以使用泰勒展开技术通过偏微分算子进行近似。 D.3 燃料单元电池或组件中的伽马传输 根据光子 BTE，裂变、辐射捕获或放射性衰变产生的能量的一部分是通过光子传输的。在某些情况下，初级光子会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 的确定性解决方案 第二个应用领域是放射治疗。 RTP 中使用电离辐射。放射治疗中基于 BTE-BFP 的模型由两个耦合方程组成，用于描述光子和电子传输。使用基于耦合的模型的确定性解决方案为扰动和灵敏度计算开辟了道路。