Safe, efficient cementation of challenging radioactive wastes using alkali activated materials with high-flowability and high-anion retention capacity

Lead Research Organisation: University of Sheffield
Department Name: Materials Science and Engineering

Abstract

In this project, we will collaboratively develop, optimise and scale-up new high-performing geopolymer cements for use in the solidification of sludge wastes that have been generated in the Fukushima Daiichi cleanup and remediation process. These wastes contain a complicated and problematic combination of radioactive elements, and are currently stored in containers awaiting final treatment (conditioning). Before the wastes can be disposed, they must be converted to a solid form, but the conventional cement blends that would usually be used for this purpose require modification or improvement so that they can give appropriate performance in making the wastes safe. For this reason, we will develop, optimise, and scale-up a set of bespoke, innovative geopolymer-type cements, produced from aluminosilicate clays, to give excellent fluidity and mixing characteristics that will enable them to be fully effective in solidifying the sludges, and outstanding performance in the long-term to prevent the release of immobilised radioactive materials. We will determine key new fundamental scientific aspects that control the materials science and chemistry of geopolymer cements in combination with iron-rich sludges, which will bring new understanding of these materials that can also be transferred to benefit other uses of geopolymer cements in nuclear and non-nuclear applications. We will work in partnership with industry to demonstrate these materials, and the associated processes for their usage, at a scale that is large enough to validate the use of this new procedure directly in the Fukushima cleanup operations. In this way, we will use advanced materials science to benefit future generations.

Planned Impact

This project will lead to the development of geopolymer technology as a highly effective and safe method for the conditioning of problematic sludges that result from nuclear remediation and decommissioning operations. This will generate impact by making available a new process, demonstrated at a useful pilot scale, for the treatment and safe long-term disposition of the problematic iron hydroxide sludge that has been generated in large quantities at the Fukushima Daiichi site. To enhance uptake and maximise the value of the project results, we will:
* conduct a major scale-up campaign led by a Japanese company (ADVAN ENG Co. ltd), to prove the material and process solutions at a realistic pilot scale
* engage directly with government bodies in Japan and site licence companies in the UK to maximise the utility of our results in both nations
* connect and interact with other UK-Japan projects and international activities in related topics, to ensure maximum synergy
* disseminate our work in the highest-profile journals and conferences to reach an academic audience
* host and run industry-focused workshops in Japan, continuing our past successes in this area, to raise visibility of our work among key decision-makers
* train excellent early-career researchers to world-best levels, helping to secure the future of nuclear research in Japan and the UK
 
Description We explored the role of iron in the formation of aluminosilicate "geopolymer" cements, with a particular view toward using these cements to immobilise iron-rich sludges that have resulted from nuclear energy generation operations and cleanup activities at the Fukushima and Sellafield sites. We have published our initial work which describes the structural role of iron that is sourced from iron-rich clays, and are continuing to develop our understanding of iron-cement interactions. Part of this work was included into a major review of iron-rich cements, published in 2022, and another review of characterisation of iron-rich cements, published in 2024. We tested the flow properties of geopolymer cements containing waste sludges, including detailed comparative analysis of materials available in the UK and Japan, to benchmark across the two partner countries and provide insight into how raw materials selection can influence the performance of geopolymer cements in a practical sense and at scale. We have published on innovative pathways to jointly immobilise complex combinations of radionuclides using some of the unique functionality that can be engineered into geopolymer cements.
The University of Sheffield cements team (B Walkley as successor to the PI of this grant after he left the UK for a job in Switzerland) was awarded funding in collaboration with Hokkaido University, NDA, and SobueClay Co, as the PI in Phase 10 of the UK-Japan Civil Nuclear scheme, to further develop the work from this project into commercially applicable outcomes for the Fukushima site.
Exploitation Route Could provide opportunities for the use of better-performing, lower-CO2 cements to immobilise difficult wastes in the nuclear sector in the UK, Japan, and elsewhere.
Sectors Construction

Energy

Environment

 
Description Extensive discussions with Sellafield Limited regarding the potential use of geopolymer cements within the UK nuclear estate; they are developing and trialling formulations at present, including work we are conducting in our labs and in partnership with NNL. NDA have funded an iCASE Award (to be co-supervised by Sellafield) to commence in Sep 2022 focused on the development of geopolymer encapsulants. Visit of team members to other UK nuclear sites to discuss the potential for alternative cements to be used in their encapsulation programme. The co-I Dr H Kinoshita, in partnership with Dr B Walkley, was awarded funding in collaboration with Hokkaido University, NDA, and SobueClay Co, as the PI in Phase 10 of the UK-Japan Civil Nuclear scheme, to further develop the work from this project into commercially applicable outcomes for the Fukushima site.
First Year Of Impact 2020
Sector Construction,Energy,Environment
Impact Types Economic

 
Description PREDIS
Amount € 23,700,000 (EUR)
Funding ID 945098 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 08/2020 
End 08/2024
 
Description Robust, Controllable Geopolymer Binders for Waste Forms
Amount £88,682 (GBP)
Funding ID iCASE Award Voucher 220144 
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 08/2022 
End 03/2026
 
Description Phase 6 project team 
Organisation Hokkaido University
Country Japan 
Sector Academic/University 
PI Contribution UK side academic lead, conducting research and collaborating with other academic & industry partners
Collaborator Contribution Hokkaido Univ - conducting research and coordinating Japan side of partnership including funding from MEXT Advan Eng - plant trials in Japan Sellafield Limited - advice and discussion of wastes in UK requiring cementation by geopolymers
Impact All project outputs are collaborative between the two universities, with guidance from industrial partners
Start Year 2019
 
Description Phase 6 project team 
Organisation Sellafield Ltd
Country United Kingdom 
Sector Private 
PI Contribution UK side academic lead, conducting research and collaborating with other academic & industry partners
Collaborator Contribution Hokkaido Univ - conducting research and coordinating Japan side of partnership including funding from MEXT Advan Eng - plant trials in Japan Sellafield Limited - advice and discussion of wastes in UK requiring cementation by geopolymers
Impact All project outputs are collaborative between the two universities, with guidance from industrial partners
Start Year 2019
 
Description Fukushima College internship 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact 5 students and 3 academic staff visited our department from Japan through Fukushima College, see our facility, had discussion on our research, and discussion with our undergraduate students.
Year(s) Of Engagement Activity 2022
 
Description IAEA School on Waste Cementation 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I presented 6 lectures over 4 weeks in the Joint ICTP-IAEA International School on Radioactive Waste Cementation, jointly organized by the IAEA and the Trieste, Italy-based Abdus Salam International Centre for Theoretical Physics (ICTP). Several of these lectures were related to the outcomes of this project. The School was held as a virtual event and attended by more than 60 practitioners, policymakers and students from 30 countries. This is a flagship event of the International Atomic Energy Agency. As a result of my participation in this event, I was also invited to join the Steering Committee of the IAEA International Predisposal Network.
Year(s) Of Engagement Activity 2020
URL https://www.iaea.org/newscenter/news/joint-iaea-ictp-virtual-school-highlights-global-interest-in-ra...
 
Description Joint ICTP-IAEA International School on Radioactive Waste Package Performance Testing 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact ~40 participants in IAEA international training school; I presented work on leaching of wasteforms
Year(s) Of Engagement Activity 2021
URL https://indico.ictp.it/event/9656/
 
Description Predis Webinars 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Webinars coordinated through the PREDIS European project, for practitioners and decision-makers in the nuclear sector to understand geopolymer applications in the nuclear sector - 2 x webinars in 2022, estimated audience 200 per webinar
Year(s) Of Engagement Activity 2022
URL https://predis-h2020.eu/events/
 
Description Project symposium (Sapporo) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Around 60 experts and stakeholders from the Japanese and UK nuclear sectors participated in the project workshop
Year(s) Of Engagement Activity 2022
 
Description Site visit - Dounreay 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact NDA-mediated visit to Dounreay to discuss waste cementation adn possibilities for alternative encapsulants
Year(s) Of Engagement Activity 2020