Development of solidification techniques with minimised water content for safe storage of secondary radioactive aqueous wastes in Fukushima

东京电力公司福岛第一核电站(NPP)受污染的水在处理过程中产生了大量二次含水废物。它们受到高度放射性污染，在加工的早期阶段生产的那些也含有大量的海盐。由于这些废物具有很大的放射性和水分含量，会产生氢气，长期储存不仅面临泄漏的潜在风险，而且还可能发生爆炸和火灾。为了安全地储存这些废物，必须紧急将它们转换成一种形式，既降低泄漏风险，又最大限度地减少因产生氢气而发生火灾的风险。因此，拟议的项目旨在开发一种将水含量降至最低的固化技术，用于安全存储福岛第一核电站的二次含水放射性废物。该项目与英国和日本有着密切的双边联系，融合了两所大学和日本原子能机构的专业知识。联合研究将侧重于二次水废物的固定化，这是有问题的，因为它们含有大量的化合物(例如90锶、镁(氢氧化镁)2、氯化钠)，使它们的化学成分复杂。我们将开发一种新的固化技术，通过热处理，基于磷酸镁和磷酸钙粘结剂的化学作用，将产生安全、被动的废物。将对这种废物进行充分的表征，并确定其辐照稳定性和长期水溶液稳定性，以加深对其在进一步临时储存或最终地质处置条件下的行为的了解。该项目的成功将提高公众和政府对福岛第一核电站退役和废物管理实践的信心，此外还将支持英国的核废料退役战略。

The processing of contaminated water from the TEPCO Fukushima Daiichi Nuclear Power Plant (NPP) results in a large amount of secondary aqueous wastes. They are highly radioactively contaminated, and those produced at the early stage of the processing also contain significant amounts of sea salt. Due to the significant radioactivity and water content, hydrogen gas is generated from these wastes, and their long-term storage faces the potential risk of not only leakage, but also explosion and fire. For the safe storage of these wastes, they must urgently be converted into a form that has a reduced risk of leakage as well as a minimised fire risk due to hydrogen gas generation. Thus, the proposed project aims to develop a solidification technique with minimised water content for the safe storage of secondary aqueous radioactive wastes from the Fukushima Daiichi NPP.The project has strong bilateral UK and Japan links, incorporating expertise from both universities and the Japanese Atomic Energy Agency. The joint research will focus on the immobilisation of secondary aqueous wastes, which are problematic since they incorporate a large number of compounds (e.g. 90Sr, Mg(OH)2, NaCl), making their chemistry complex. We will develop a novel solidification technique, through heat-treatment, based on magnesium phosphate and calcium phosphate cement chemistry that will result in a safe, passive wasteform. This wasteform will be fully characterised and its irradiation stability and long-term aqueous stability will be determined, to develop an understanding of its behaviour under further interim storage or final geological disposal conditions. The success of the project will lead to improved public and government confidence in the decommissioning and waste management practises at the Fukushima Daiichi NPP, in addition to supporting UK nuclear waste decommissioning strategies.