Simulated Used Nuclear Fuel Dissolution as a Function of Fuel Chemistry and Near Field Conditions

这项研究是英国和美国共同努力，以了解使用过的核燃料（UNF）的长期安全性，核裂变发电产生的主要废物。由于全世界有440多个商业核电站在运作，因此产生了大量的联合国基金会累积库存，约为300 000公吨。在英国，几个新的核反应堆计划建设（如欣克利角C），联合国基金会在塞拉菲尔德（ThORP）的后处理能力将于2018年关闭。因此，目前估计为3，500 - 8，000吨的英国库存将继续增长。美国目前（2016年4月）有80，150公吨UNF，预计到2050年左右，当所有目前正在运行的反应堆达到其指定寿命时，总量约为140，000公吨。英国和美国目前没有UNF的最终处置途径;目前，燃料储存在冷却池（英国和美国）或干式储存（仅美国）中，但这不是可持续的最终解决方案。这两个国家一致认为，在深层（200米至1 000米）地质构造中进行处置是最合适的解决办法，因为这将使联合国基金会与生物圈和未来人口隔离10万年以上-在这段时间内，这种材料将具有高度放射性。在这种地质处置设施中，放射性核素向环境的释放将通过联合国基金会与地下水以及与作为废物周围工程屏障而建造的材料，特别是燃料包壳和金属罐的相互作用来控制。UNF如何在GDF条件下与地下水相互作用的基本机制的理解对于英国和美国的废物管理计划至关重要，这些计划旨在满足公民和监管机构关于UNF长期退化预测的可靠性，这些预测来自各种燃料设计，燃耗，反应堆操作和储存条件。该研究项目被设想为来自英国和美国的领先研究人员之间的合作和联合企业，他们共同带来了相互补充和兼容的技能，能力和兴趣，以实现我们对UNF溶解的基本理解的范式转变，在包层和罐材料的存在下，以及当地的地下水条件。这一认识将加强联合国基金会在不同处置条件下的演变和相互作用模型的成熟，从而能够可靠地预测退化和调整处置条件，以实现所需的长期性能，并为预测长达100万年的行为提供信心。

This research is a joint UK and US effort to understand the long-term safety of used nuclear fuel (UNF), the primary waste arising from the generation of electricity by nuclear fission. With more than 440 commercial nuclear power stations operating worldwide, a significant cumulative inventory of UNF has been produced, on the order of 300,000 metric tonnes. In the UK, several new nuclear reactors are planned for construction (e.g. Hinkley Point C), and the UNF reprocessing capability at Sellafield (ThORP) is due to close in 2018. Hence, the UK inventory, currently estimated at 3,500 - 8,000 tonnes, will continue to grow. The US currently (April 2016) has 80,150 metric tonnes of UNF, with a prediction of a total of approximately 140,000 metric tons by around 2050 when all currently operating reactors reach their designated life.The UK and the US presently have no final disposal route for UNF; fuel is currently stored in cooling ponds (UK and US) or dry storage (US only), but this is not a sustainable final solution. Both countries agree that disposal in a deep (200 m - 1000 m) geological formation is the most suitable solution, since it will isolate the UNF from the biosphere and future populations for more than 100,000 years - the period of time for which this material will be highly radioactive. In such a Geological Disposal Facility (GDF), the release of radionuclides to the environment will be controlled by the interaction of the UNF with groundwater, and with the materials that have been built as an engineered barrier around the waste, particularly the fuel cladding and the metal canister. Fundamental mechanistic understanding of how UNF interacts with groundwater under GDF conditions is of paramount importance for UK and US waste management programs, which seek to satisfy citizens and regulators regarding the reliability of long-term degradation predictions for UNF originating from a variety of fuel designs, burn-ups, reactor operations, and storage conditions. This research project is envisioned as a collaborative and joint enterprise between leading researchers from the UK and US who, collectively, bring mutually complementary and compatible skills, capabilities, and interests required to achieve a paradigm shift in our fundamental understanding of UNF dissolution in the presence of cladding and canister materials, and local groundwater conditions. This understanding will underpin the maturation of models for UNF evolution and interaction under different repository conditions, enabling reliable prediction of degradation and adjustment of repository conditions to achieve desired long-term performance and providing confidence in predicting behaviour for up to one million years.