Development of advanced leakage models for lattice calculations based on the method of characteristics.

基于特征方法开发用于晶格计算的先进泄漏模型。

• 批准号: RGPIN-2016-06416
• 负责人: Marleau, Guy
• 金额: $ 2.77万
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687089
• 关键词: Development; advanced; leakage; models; lattice

The long-term objectives of this research program are to develop and implement in transport based lattice codes new or improved numerical simulation techniques to make them more precise and efficient tool to analyse neutrons behaviour in nuclear reactor. This implies: developing new computational models to treat more complex systems; programming robust method to accelerate the solution algorithm for large neutron transport problems; and developing computation schemes benefiting from recent advances in computer technology. Most of the development we proposed will be implemented in the code DRAGON we developed at Polytechnique Montreal. This freely distributed software is used in Canada and abroad for the safety analysis of CANDUs as well as in Laboratories and Universities throughout the world for advanced reactor studies.***Lattice codes are mainly used to provide spatially homogenized and energy condensed cross sections for finite core calculation software. For currently operating reactors, this implies performing 2D or 3D neutron transport simulations over fully reflected fuel assemblies. However, nuclear reactors are finite which means neutron will escape from the lattices. This is where leakage models are useful because they provide a mean to simulate this effect in a critical lattice in addition to producing a more representative flux distribution to use for fuel burnup and lattice homogenization. Currently, the most advanced heterogeneous leakage method implemented in lattice codes is the simplified heterogeneous B1 model but its use is limited to the collision probability (CP) method in fully reflected symmetric 2D geometries (axially infinite cell).***The short-term goal of this research program is to take advantage of the fact that the method of characteristics (MoC) programmed in DRAGON can solve the transport equation for high order angular flux modes to develop the heterogeneous BN leakage model. As a first step we will implement, my students and I, an advanced B1 heterogeneous leakage method in DRAGON using the MoC in fully reflected non-symmetric 2D geometries. For the second step, work will proceed on generalizing the BN method to 3D geometries with mixed boundary conditions (void axially and white reflection radially). Thirdly, we will develop a 3D cyclic tracking procedure so that mirror like reflection boundary conditions can be treated in the 3D transport solution. This will increase substantially the performance of DRAGON for 3D simulations by removing the computational penalties resulting to the presence of small surfaces at external boundaries. Finally we will propose and implement an advanced acceleration techniques for 3-D full core Monte Carlo simulations. This will be based on an iterative algorithm to solve the fine mesh MoC equation with incoming angular flux boundary conditions generated by a coarse mesh Monte Carlo simulation.**

该研究计划的长期目标是在基于运输的晶格代码中开发和实施新的或改进的数值仿真技术，以使其更精确，更有效地分析核反应堆中的中子行为。这意味着：开发新的计算模型来处理更复杂的系统；编程强大方法，以加速解决方案算法，以解决大型中子运输问题；并制定计算机技术进步受益的计算方案。我们提出的大部分开发都将在我们在蒙特利尔Polytechnique开发的代码龙中实施。该自由分布的软件在加拿大和国外使用，用于对糖果的安全分析以及全球的实验室和大学进行高级反应堆研究。核心计算软件。对于当前操作的反应堆，这意味着对完全反射的燃料组件进行2D或3D中子传输模拟。但是，核反应堆是有限的，这意味着中子将从晶格中逃脱。在这里，泄漏模型是有用的，因为它们提供了在关键晶格中模拟这种效果的平均值，此外还可以产生更具代表性的通量分布来用于燃料燃烧和晶格均质化。目前，晶格代码中实施的最先进的异质泄漏方法是简化的异质B1模型，但其使用仅限于完全反射的对称的对称2D几何（轴向无限单元）中的碰撞概率（CP）方法。***短期的短期。该研究计划的目标是利用龙中编程的特征方法（MOC）可以解决高阶角通量模式以开发异质BN泄漏模型的传输方程。作为第一步，我们将实施，我和我的学生是龙的高级B1异质泄漏方法，使用MOC在完全反射的非对称2D几何形状中使用MOC。在第二步中，将继续将BN方法推广到具有混合边界条件的3D几何形状（轴向上和白色反射）。第三，我们将开发一个3D循环跟踪程序，以便可以在3D传输溶液中处理镜像反射边界条件。这将通过消除导致外部边界上小表面的计算惩罚来大大提高龙的性能。最后，我们将为3-D完整的Monte Carlo模拟提出并实施高级加速技术。这将基于一种迭代算法，以解决由粗网格蒙特卡洛模拟产生的传入的角通量边界条件来求解精细的网格MESH方程。**