工业核反应堆中中子噪声的高保真蒙特卡洛模拟

该博士项目专注于模拟核反应堆中的中子噪声，具体采用蒙特卡洛方法来解析由各种扰动引起的波动。其目标是为轻水反应堆和熔盐反应堆增添新的模拟功能，同时完善 TRIPOLI-5 代码，并研究 GEN-IV 设计中噪声源的理论基础。

Job description: Project description: Operating nuclear reactors are subject to a variety of perturbations. These can include vibrations of the fuel pins and fuel assemblies due to fluid-structure interactions with the moderator, or even vibrations of the core barrel, baffle, and pressure vessel. All of these perturbations can lead to small periodic fluctuations in the reactor power about the stable average power level. These power fluctuations are referred to as “neutron noise”. Being able to simulate different types of in-core perturbations allows reactor designers and operators to predict how the neutron flux could behave in the presence of such perturbations. In recent years, many different research groups have worked to develop computational models to simulate these sources of neutron noise, and their resulting effects on the neutron flux in the reactor. The primary objective of this PhD thesis will be to bring Monte Carlo neutron noise simulations to the scale of real-world industry calculations of nuclear reactor cores, with a high-fidelity continuous-energy physics representation. As part of this process, the student will add novel neutron noise simulation capabilities to TRIPOLI-5, the next-generation production Monte Carlo particle-transport code jointly developed by CEA and ASNR, with the support of EDF. As a first step, the student will assess the performance and behavior of different neutron noise models in continuous-energy simulations at the scale of a single fuel assembly, and potentially at the full core level, using the preexisting neutron noise Monte Carlo code developed in the framework of a PhD thesis in our unit. These results will be then used to inform the decision of what neutron noise model to implement in TRIPOLI-5. While the main application of the new solver will be the simulation of the noise field resulting from perturbations occurring in light-water reactors, the student will concurrently study the theoretical basis of perturbations occurring in Molten Salt Reactors (MSRs), to develop theoretical models for different noise sources which could occur in these GEN-IV reactor designs. Contrary to solid-fuel reactors, in MSRs the fuel is in liquid form and thus advected in the core, which entails the displacement of delayed neutron precursors: the delayed fission operator occurring in the noise equations is subtly modified with respect to the case of solid-fuel reactors, and should be properly taken into account. The next step will be to transfer the existing neutron noise implementation from the mini-app to TRIPOLI-5. This must include support for particles with complex statistical weights, and the weight cancellation variance-reduction technique, which are required in order to achieve reasonable statistical convergence for noise simulations, as shown in previous investigations. Additionally, the student will develop specific models for the “sources” of noise which appear in real world reactors. These will include vibrations of fuel pins or fuel assemblies, density oscillations, and and temperature oscillations. Once implemented in TRIPOLI-5, these new neutron noise features will be put to the test, examining a variety of perturbations at the scale of a full PWR core for fuel assembly vibrations and other perturbations of interest. Time permitting, simulations of neutron noise in MSRs will also be simulated and examined, and their behavior will be contrasted to that of solid-fuel reactors subject to comparable noise sources.

所需个人背景与技能： 工程文凭及/或数值模拟与/或反应堆物理学硕士学位