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联合开展的，旨在了解使用过的核燃料(UNF)的长期安全性。使用过的核燃料是通过核裂变发电产生的主要废物。全球有440多座商业核电站在运行，联合国森林基金的累积库存相当可观，约为30万公吨。在英国，计划建造几个新的核反应堆(例如欣克利角C)，联合国核电站在塞拉菲尔德(索普)的后处理能力将于2018年关闭。因此，英国的库存(目前估计为3500至8000吨)将继续增长。美国目前(2016年4月)拥有80,150公吨UNF，预计到2050年左右，当所有当前运行的反应堆达到指定寿命时，总计约为140,000公吨。英国和美国目前没有UNF的最终处置路线；燃料目前存储在冷却池(英国和美国)或干库(仅限美国)，但这不是一个可持续的最终解决方案。两国一致认为，在深(200米-1000米)的地质地层中处置是最合适的解决方案，因为这将使联合国森林论坛与生物圈和未来的人口隔离超过10万年--在这段时间内，这种材料将具有高放射性。在这样的地质处置设施(GDF)中，放射性核素向环境的释放将受到联合国基金会与地下水以及作为废物周围工程屏障而建造的材料，特别是燃料包层和金属罐之间的相互作用的控制。对于英国和美国的废物管理项目来说，从根本上了解联合国燃料与地下水在GDF条件下的相互作用是至关重要的，这些计划试图让公民和监管机构相信，来自各种燃料设计、燃烧、反应堆操作和储存条件的联合国燃料长期退化预测的可靠性。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事业，他们共同带来相互补充和兼容的技能、能力和兴趣，以实现我们对存在覆层和罐材料的联合国基金会溶解以及当地地下水条件的基本理解的范式转变。这一理解将巩固联合国森林论坛在不同储存库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储存库条件的退化和调整，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.