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

东京电力公司（TEPCO）福岛第一核电站（NPP）污水处理过程中产生大量的二次废水。它们受到高度放射性污染，在加工的早期阶段生产的产品也含有大量海盐。由于这些废物具有显著的放射性和含水量，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。为了安全储存这些废物，必须立即将其转化为一种泄漏风险降低以及由于氢气产生而导致的火灾风险最小化的形式。因此，拟议项目旨在开发一种含水量最小的固化技术，用于安全储存来自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，结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含水废物的固定，这是一个问题，因为它们含有大量化合物（例如90 Sr，Mg（OH）2，NaCl），使其化学复杂。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骨水泥化学，这将导致一个安全的，被动的废物形式。将对这种废物形态进行充分的定性，并确定其辐照稳定性和长期水稳定性，以便了解其在进一步的临时储存或最终地质处置条件下的行为。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流程的信心，并支持英国的核废物退役战略。

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.