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Mechanisms of Retention and Transport of Fission Products in Virgin and Irradiated Nuclear Graphite

原始和辐照核石墨中裂变产物的保留和传输机制

基本信息

批准号：
EP/R005745/1
负责人：
Kenny Jolley
金额：
$ 40.76万
依托单位：
Loughborough University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FR005745%2F1
关键词：
Mechanisms Retention Transport Fission Products

项目摘要

The UK has long experience in the operation of Advanced Gas-cooled Reactors, which rely many tonnes of nuclear-grade graphite which has a dual role, firstly to slow down (moderate) neutrons to enhance nuclear fission and secondly to provide structure in the rather extreme environment in the reactor core, comprising high temperatures and intense radiation.Designs of reactor for the next generation of nuclear reactors being developed in the USA, such as high temperature gas reactors and molten salt reactors also rely on graphite, and will require a good scientific understanding of its properties under irradiation, particularly under higher temperature conditions. Therefore, fundamental studies are required to reveal the mechanisms underlying graphite behavior, before these new reactor concepts can be taken through the design process and be licensed for operation.A big issue for these new reactor designs is the retention of activated fission products within graphite, and their subsequent potential release during decommissioning. This includes the complex graphitic matrix material used in fuel pebbles for Pebble Bed Modular Reactor designs. This is a joint experimental-computational approach to measure the diffusivities of fission products (FPs) - Iodine (I), Cesium (Cs), Krypton (Kr), Strontium (Sr), Ruthenium (Ru) and Silver (Ag), and Europium (Eu) in four graphite grades - HOPG, NBG-18, PCEA and IG-110, and uncover the mechanisms of transport using multiscale simulations involving electronic structure, atomistic, and phase field methodsThe UK teams at Manchester and at Loughborough will be working with the USA groups based in University of Central Florida, North Carolina State University and Oak Ridge National Laboratory on this problem. Manchester will be contributing experimental measurements on legacy graphite from the AGR and Magnox reactor programmes and Loughborough will be using theoretical methods to elucidate electronic structure and energy landscapes of the FPs within realistic models of the graphite at the beginning of service, and graphite after decades of exposure to neutron and gamma radiation.

英国在先进的气体冷却反应堆方面有着长期的运营经验，它依赖于许多吨核级石墨，具有双重作用，首先是减缓(中等)中子以促进核裂变，其次是在反应堆核心相当极端的环境中提供结构，包括高温和强烈辐射。美国正在开发的下一代核反应堆的反应堆设计也依赖于石墨，这需要对其在辐照下的性质有很好的科学了解，特别是在更高的温度条件下。因此，在这些新的反应堆概念可以通过设计过程并获得运行许可之前，需要进行基础研究来揭示石墨行为的机制。这些新的反应堆设计的一个大问题是活化的裂变产物在石墨中的保留，以及它们在退役期间随后的潜在释放。这包括用于卵石床模块化反应堆设计的燃料鹅卵石中的复杂石墨基材料。这是一种联合实验和计算方法，旨在测量裂变产物(FP)-碘(I)、铯(Cs)、氪(Kr)、锶(SR)、Ru(Ru)和银(Ag)以及Eu(Eu)在四个石墨等级-HOPG、NbG-18、PCEA和IG-110中的扩散系数，并使用涉及电子结构、原子和相场方法的多尺度模拟来揭示传输机制。英国曼彻斯特和拉夫堡的团队将与位于中佛罗里达大学、北卡罗来纳州立大学和橡树岭国家实验室的美国团队合作解决这个问题。曼彻斯特将对AGR和Magnox反应堆计划遗留的石墨进行实验测量，拉夫堡将使用理论方法在实际模型中阐明FPS的电子结构和能量格局，这些模型包括服役初期的石墨以及暴露在中子和伽马辐射数十年后的石墨。