Novel restoration materials for clean-up of radionuclides in the environment

Despite tremendous technological and financial effort in Japan to deal with the effects of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident many challenges remain. The Government of Japan's Committee on Countermeasures for Contaminated Water Treatment considered existing and proposed measures and technologies "to remove" contaminated water, "to keep out" the inflow of water into the sources of contamination and to "prevent leakage" of contaminated water into the environment. They concluded in a December 2013 report that it was difficult to take effective measures using only existing general knowledge and the committee asked for technical information to be further gathered from both domestic and overseas experts in the following six topics: (1) Storage of contaminated water, (2) Treatment of contaminated water, (3) Removal of radioactive materials from the seawater in the harbour, (4) Control of contaminated water within buildings, (5) Site management to restrict groundwater flowing into the site, and (6) Understanding groundwater flow including the behaviour of radionuclides. In this work efforts will be made to tackle aspects of topics 3, 4 and 5. The most problematic radionuclides at the FDNPP are Sr-90, Cs-134 & Cs-137 because they form highly soluble salts and have environmental behaviour similar to the common (excess) groundwater ions Ca2+ and K+, respectively, hence they are mobile, bioavailable and of immediate concern. Initial work at the FDNPP focused on removal of Cs at the plant and in storage vessels, this project aims to also cover the clean-up of Sr-90 and Co-60.

This joint UK/Japan (University of Birmingham, Japanese Atomic Energy Agency, Kyushu University, College of Engineering at Shibaura Institute of Technology) proposal will build on the work of an established internationally leading collaboration for the development, characterisation and testing of three novel systems for immobilisation of radionuclides. The novelty of the first set of materials is that they are designed to be removable by magnetic separation rather than traditional gravity fed fixed bed column system where effluent needs to be pumped into the system. This gives engineering flexibility and scope for use in the field; for example they could be positioned deposited in contaminated water and then magnetically collected along with attached radionuclides. The novelty of the second set of materials are that they are being designed to be made by halophilic organisms, i.e. those that live in high salt concentration environments such as seawater, and could therefore be produced and used in decontamination of harbour seawater or saline groundwater near the FDNPP. The novelty and importance of the final set of materials is a design so that they can be poured or injected into the ground to form porous barriers that will trap the targeted radionuclides and prevent their further migration. All three sets of materials will be characterised using advanced instrumentation so that the mechanism of radionuclide entrapment and the stability of incorporation is fully understood.

These materials will not only assist in the clean-up at the FDNPP but will also be available for the abatement of any future accidents and may have a role to play in UK decommissioning activities and legacy waste clean-up. Within this project the goal is to evaluate the scope of the three sets of materials to provide key data and a platform to underpin further development and process implementation in conjunction with Japanese Chemical and Civil Engineers.

There are three distinct non-academic groups who will benefit from this project: companies and agencies involved in nuclear waste clean-up and decommissioning activities; Government, regulators and implementation authorities; and general society. The first group will benefit through the provision of new materials and methods to clean up existing nuclear waste generated by the accident at the Fukushima Daiichi Nuclear Power Plant, legacy waste in the UK being managed by Sellafield Ltd and other site license operators and wastes that will be generated during the continuing programme of decommissioning not only in Japan and the UK but globally as reactors come to the end of their lifetimes. Government, regulators and implementation authorities will benefit through provision of knowledge and methods for tackling nuclear clean-up in a safe, effective way that can form part of regulated strategies and future policy. General society will benefit as this work will help to facilitate environmental restoration and also (via outreach activities) show that these difficult problems can be solved and that nuclear energy should continue to be a part of a low carbon energy mix in the UK.

Importantly, today's new reactor build is being hindered by the need to factor-in decontamination costs at the outset and it is hard to calculate these due to a paucity of information. Likewise, insurance is hard to obtain if the premium cannot be set and this can be done only with an estimate of the likely costs involved in clean-up in a 'worst case' scenario. By the end of this project with the data we obtain, we should be in a position to start to inform costs of possible solutions. In this, biomanufacturing is a 'new player' that has the major advantage that bacteria can be grown, quickly and scalably, on very simple (indeed waste) materials and that they build structured minerals from cheap ingredients which can be sourced as wastes from other processes. As the materials' capture properties benefit from moderate heating this has the dual benefit of destroying the bacteria and organic components to forestall potential risks and environmental concerns.

New immobilisation materials and technologies would be of international interest and potential use, helping to fulfil a stated aim of the 2013 HMGovernment strategy document "The UK's Nuclear Future" where a key aim is the "UK having a clear competitive edge in waste management and decommissioning technologies...through innovation and experience." This work would therefore help to promote UK government policy and directly benefit policy makers. Some aspects would help inform clean-up of legacy waste in the UK and be useful for decommissioning activities, thereby helping to inform decisions of the NDA and site license operators at Sellafield and other UK sites.

A huge challenge in the nuclear expansion which the UK must embrace to fill the impending 'energy gap' is to win public support and confidence. Our displays in schools within various PE awards have revealed a strong interest in young people to embrace nuclear technology with open minds. These are the policymakers, engineers and the insurers of tomorrow and by fostering interest we hope to attract a new generation of 'enablers' and 'implementers' ( UB offers formal training via its various relevant MSc courses, with the future possibility for part-study in Japan and vice versa). At the same time the wider public is, on the whole, thirsty for a balanced debate to help inform on final disposal solutions- a 'community issue' - and our work will continue to be conveyed via impartial public platforms such as radio (e.g. BBC:The Naked Scientists: live, phone-in) and also its associated web tools