Performance Assessment and Development of Mineral-Based Cements at High Pressure and Temperature for Deep Borehole Disposal of HLW and SNF

需要确保低碳能源以满足日益增长的电力需求，这使得越来越多地使用核能几乎是必然的。核能与所有其他形式的能源一样，会产生废物，包括高放射性废物和乏燃料。世界上任何地方尚未实施任何环境和政治上令人满意的乏燃料处置解决方案。乏燃料的主要问题是高辐射加热。在瑞典KBS-3概念或为联合王国和其他一些欧洲国家提出的类似设计等开采的工程处置库中进行处置，将需要长时间的反应堆后冷却，即使这样，也会对工程屏障造成严重限制。在过去的十年中，我们（谢菲尔德大学的Gibb、Travis、McTaggart和同事）已经开发了一种处理SF的替代概念，特别是可能从新建电站的第三代反应堆中去除的高燃耗SF。这一替代方案是基于在地质钻孔中非常深的处置。深钻孔处置利用地质屏障的数量级增加（超过开采的处置库），可能是SF的一个更安全的选择，可以更快地实施，成本仅为处置库的一小部分。拟议的研究计划是进一步发展钻孔处置，使我们大大扩展其适用性，使安全，有效的长期处置范围更广的SFs从非常年轻的热燃料，以旧的，legacy SFs.Our目前的钻孔处置概念高发热SFs将利用一种特殊的铅基合金，作为一个罚款shot雇用。这种材料被设计成支撑废物容器的叠加堆的负载，并且通过废物的辐射加热，变成流体并填充钻孔中和周围的任何剩余裂缝，形成永久密封，并且在随后冷却时形成额外的屏障。该系统不是通用的全能型系统;对于某些废物装载，例如在处置旧燃料期间，将产生不足以熔化弹丸的热量。我们正寻求通过开发地热水泥作为铅基合金支撑基质的替代品，将处置方案的灵活性扩展到所有SF。拟议的研究将根据典型钻孔处置方案的热流模型确定一系列候选地热水泥。我们经验丰富的团队包括：地热水泥国际专家Neil Milestone博士;乏燃料处置深钻孔概念的创始人费尔格斯吉布教授;以及多尺度建模专家Karl Travis博士，他们将开展一项基于实验的研究计划，通过测量粘度、凝固时间、耐久性和地球化学等重要特性，减少候选水泥的数量。如果没有找到合适的材料，将尝试使用调查结果来开发适合目的的材料。成功的结果很可能会产生一种产品，用于核废料包装和处置以及碳氢化合物和地热钻探工业的其他领域。

The need to secure a low-carbon energy source to meet the ever-increasing demand for electricity makes the increasing use of nuclear power a virtual certainty. Nuclear power, like all other forms of energy, generates waste, including high-level radioactive waste and spent fuel (SF). No environmentally and politically satisfactory solution has yet been implemented anywhere in the world for the disposal of spent fuel. The main problem with spent fuel is the high radiogenic heating. Disposal in a mined, engineered repository such the Swedish KBS-3 concept or similar designs proposed for the UK and some other European countries would require prolonged periods of post-reactor cooling and even then would place severe constraints on the engineered barriers. Over the last decade, we (Gibb, Travis, McTaggart & co-workers at the University of Sheffield) have developed an alternative concept for dealing with SF, particularly the high burn-up SF likely to be removed from GEN III reactors in new-build power stations. This alternative is based on very deep disposal in geological boreholes. Deep borehole disposal which utilises an order of magnitude increase in the geological barrier (over and above a mined repository) is potentially a safer option for SF, could be implemented faster and at a fraction of the cost of a repository. The proposed research programme is to further develop borehole disposal such that we greatly extend its applicability to enable the safe, efficient long term disposal of a much wider range of SFs from very young hot fuel to older, legacy SFs.Our current borehole disposal concept for high heat-generating SFs would utilise a special lead-based alloy, employed as a fine shot. This material is designed to support the load of an overlying stack of waste containers and, through radiogenic heating by the waste, becomes fluid and fills any remaining crevices in and around the borehole, forming a permanent seal, and extra barrier upon subsequent cooling. This system is not a universal catch-all; for some waste loadings, insufficient heat will be generated to melt the shot, e.g. during disposal of older fuel . We are seeking to extend the flexibility of our disposal scheme to all SFs by developing a geothermal cement as an alternative to the lead-based alloy support matrix. The proposed research will identify a range of candidate geothermal cements based on heat flow modelling of typical borehole disposal scenarios. Our experienced team which includes: an international expert in geothermal cements, Dr Neil Milestone; the originator of our deep borehole concept for spent fuel disposal, Professor Fergus Gibb; and an expert in multiscale modelling, Dr Karl Travis, will conduct a programme of experimentally based research to reduce the list of candidate cements by measuring important properties such as viscosity, setting time, durability and geochemistry. If no suitable material is found, an attempt will be made to use the results of the investigation to develop one that is fit for purpose. It is highly probable that a successful outcome would yield a product with applications in other areas of nuclear waste packaging and disposal as well as the hydrocarbon and geothermal drilling industries.