Waste implications from minor impurities in European DEMO materials
Waste implications from minor impurities in European DEMO materials
复制标题
欧洲 DEMO 材料中微量杂质造成的废物影响
作者：
Mark R. Gilbert;T. Eade;T. Rey;R. Vale;C. Bachmann;Ulrich Fischer;N. Taylor
对未来示范聚变发电厂(DEMO)的废物产生预测是必要的，以准确地描绘在寿命结束时处置放射性废物可能造成的环境和经济成本。结合蒙特卡罗中子输运模拟、库存计算以及广泛和可重复使用的后处理算法的综合模拟过程被用于不断演变的欧洲示范设计，以量化反应堆容器的各个区域和部件以及整个反应堆不同废物类别中随时间变化的质量库存。基于英国和法国法规的废物分类显示，结构钢中包含的少量杂质，特别是Eurofer，以及钨和铍等功能材料中的微量杂质，可能会对其废物分类前景产生重大影响。对当前欧洲演示概念的预测表明，在近地表储存库中将熔融结构钢废物作为低水平废物(LLW)处理可能存在问题。对这些预测的微妙之处，特别是关于14C和94Nb等长寿命放射性核素的生产的详细分析表明，仅在某些情况下才刚刚超过被接受为低放废物的门槛。在此背景下讨论了几种缓解办法。为这些评估开发的计算框架可以快速、持续地应用于成熟的演示设计，帮助指导设计选择，以减少长期废物的产生，并确保大多数废物在几十年内成为低废物或更好的废物。
Waste-production predictions for the future demonstration fusion power plant (DEMO) are necessary to produce an accurate picture of the likely environmental and economic costs of radioactive waste disposal at end-of-life. An integrated simulation process combining Monte-Carlo neutron transport simulations, inventory calculations, and extensive and reproducible post-processing algorithms has been used for the evolving European DEMO designs to quantify the time-varying mass inventories in different waste classes for individual regions and components of the reactor vessel, as well as for the reactor as a whole. Waste categories based on UK and French regulations reveal that minor impurities contained in structural steels, particularly Eurofer, as well as in functional materials such as tungsten, and beryllium, can have a significant impact on their waste classification prospects. Predictions for current European DEMO concepts suggest that there may be an issue in disposing of fusion structural-steel waste as low-level waste (LLW) in near-surface repositories. Detailed analysis of the subtleties of these predictions, particularly with regard to the production of long-lived radionuclides such as 14C and 94Nb, reveal that the threshold for acceptance as LLW is only just exceeded in some situations. Several mitigation approaches are discussed in this context. The computational framework developed for these assessments can be rapidly and continuously applied to the maturing DEMO design, helping to guide design choices to mitigate long-lived waste production and ensure that most waste becomes LLW or better within a few decades.