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Thermal treatment for radioactive waste minimisation and hazard reduction

Periodic Reporting for period 2 - THERAMIN (Thermal treatment for radioactive waste minimisation and hazard reduction)

Reporting period: 2018-12-01 to 2020-05-31

Low- and intermediate-level waste (LILW) is one of the least radioactive nuclear waste but the tonnages involved are by far the greatest. Volume and hazard of LILW can be reduced by appropriate pretreatment technologies and in most cases by improving simultaneously safety of long disposal. Thermal treatment technologies may be applied to a wide range of radioactive waste streams.
Thermal treatment can result in significant volume and hazard reduction, both of which are beneficial for safe storage and disposal. Reduction in volume supports an application of the Waste Hierarchy, which is mandatory under EU directives. It allows the best use of disposal capacity and could result in large cost savings.
The overall objective of the THERAMIN project was to provide improved safe long-term storage and final disposal of low-level wastes (LLW) and intermediate-level wastes (ILW), which are suitable for thermal processing. Work was aimed to identify radioactive wastes that could benefit from thermal treatment, of which technologies were under development in participating countries, and how these could be combined to deliver a wide range of benefits.
The project consisted of five Work Packages (WPs). Project management and coordination was done in WP1. WP2 evaluated the potential for thermal treatment of waste streams from across Europe and in WP3, the application of selected thermal treatment technologies was demonstrated and evaluated. WP4 focused on assessment of the disposability of thermally treated radioactive waste products. The synthesis of the project outcomes was done in WP5 as well as dissemination of the results.

WP2 evaluated the potential for thermal treatment of particular waste streams (across the EU and Ukraine) including consideration of where the greatest benefits from EU-wide collaboration may be realized. A methodology to support decision-making on the potential use of thermal treatment technologies to treat various radioactive wastes was developed. Waste streams in Europe potentially suitable for thermal treatment and potential thermal treatment technologies available in Europe were identified

The availability and maturity of thermal treatment technologies within Europe was summarised. Potential technologies and example facilities were identified, and the range of wastes they had demonstrably treated, or are theoretically capable of treating, was considered.

A Value Assessment methodology was developed in WP2. It was intended to assist stakeholders in assessing the ‘value’ of a treatment technology when used to thermally treat a particular radioactive waste stream. The methodology is a generic starting point that can be tailored to the needs and context in which the assessment is being completed.

Work within WP3 demonstrated the thermal treatment of a range of waste groups. The demonstrations were carried out at existing thermal treatment facilities of project partners: the SHIVA, In-can Melter, Geomelt®, thermal gasification, vitrification and hot isostatic pressing (HIP). Demonstration trials are described in detail in D3.2 Summary of Demonstration Trials Carried Out Under WP3.
In order to be disposed of, radioactive waste or waste products must comply with the Waste Acceptance Criteria (WAC) for a disposal facility. The WAC identifies the characteristics required in a waste product in order to ensure that the waste cannot have a significant detrimental impact on the long-term safety provided by the disposal facility. Compliance with the WAC is confirmed by characterisation of the thermally treated products. WP4 focused on characterisation and assessment of the disposability of the treated waste products from demonstrations within WP3.

A set of generic disposability criteria were derived following review of national WAC and other disposability requirements applied in individual countries. The generic disposability criteria were intended to be applicable to any packaging or disposal concept, any thermally treated waste, and any disposal environment. The generic disposability criteria were developed taking into account the impacts of thermal treatment. Characterisation requirements for thermally treated products were identified in order to test compliance against each criteria.

Characterisation tests were completed for treated products from demonstrations carried out within WP3 and for some additional samples. The results are presented in D4.2 Characterization of thermally treated waste products.

The disposability of thermally treated waste products and the resulting secondary wastes was evaluated for a subset of the characterised samples, based on the disposability criteria of the country in question or the generic WAC developed in the project. Assessments were completed for near-surface and geological disposal facilities.
Dissemination of the knowledge and the project results was done at WP5. Dissemination activities involved a variety of activities, including training, organisation of a project conference and development of a project synthesis report.
Training placements in conjunction with the thermal treatment trials were hosted by three project partners. A technical training school (20 attendees) was held at CEA in Marcoule in June 2019. Presentations from the course were also made available on the THERAMIN website.

The THERAMIN Conference held in February 2020 in Manchester. The EC also funded three students attending the conference as part of the training activities.

WP5 was also responsible on the preparation of the synthesis report of the THERAMIN project. Report is publicly available and it presents an overview of the main research, activities and outcomes of the project.
Thermal treatment of radioactive waste is known to offer several benefits e.g. volume reduction, destruction of toxic compounds, stable final waste form, etc. Suitability of thermal treatment technologies for different radioactive waste types have been studied and reviews of them have been presented. In THERAMIN project six different thermal treatment technologies were demonstrated and suitability of these technologies for treatment of different type of wastes was assessed. The THERAMIN project provided tools to compare these technologies with each other and with established baselines, where present. The thermally treated products of these and other trials have also been characterised and these data has been used to undertake preliminary disposability assessments. Although further studies of long-term leaching behaviour are required, the destruction of organic species by thermal treatment has been demonstrated to provide benefits in terms of reduced waste volume, reduced gas generation and removal of complexants that could increase the rate of radionuclide transport within the disposal facility.

An essential output of the project is the developed methodology to support decision-making on the potential use of thermal treatment technologies to treat various radioactive wastes.

In addition, a community of thermal treatment specialists has been established through the THERAMIN project, which provides a forum for sharing experience, understanding challenges, discussions and identification of potential solutions. At the THERAMIN conference in February 2020 in Manchester opportunities to continue to develop this community were identified, including related work in the new EC PREDIS (Predisposal waste management) project.
Figure 3. VTT thermal gasification pilot plant
Figure 1. In-can melting pilot plant CEA/Orano
Figure 2. NNL Geomelt vitrification facility