September 8, 2022
This week we warmly welcomed Dr Tatiana Grebennikova to Seoul National University, Nuclear Fuel Cycle & Nonproliferation Lab (SNUNFC) as a visiting scholar where she will work closely with our molten salts team. Joining us from the University of Manchester (UoM) Department Chemical Engineering, Dr Grebennikova has many years of experience working with molten salt technologies throughout her PhD and PDRA research under the supervision of Dr Clint Sharrad. Drawing on her years of experience, she will look to assess the feasibility of employing zeolites for in-situ removal of contaminants from molten salts. Her visit also gives rise to the opportunity of further exploring the practical application of LIBS for online monitoring of molten salt systems, building upon recent successes within the group. Dr Grebennikova joins us as part of the DAWNMANTLE project, one of many ongoing nuclear decommissioning projects between the UK and South Korea.
Evaluation of Zeolites for Online Fission Products Removal from Chloride salt Mixtures
Molten salts are among the primary candidates for heat transfer media to be used as primary and secondary coolants for next-generation fission and fusion reactor system, as well as for advanced spent fuel separation technologies. However, during operation, the accumulation of fission products (FPs) in the core of a vessel could create a significant issue, which over time will lead to a change in the physical and chemical state of the salt.
These salts will need to be replaced; however, for waste minimization and reactor economy, it is advised to recover the useful components, by separating the FPs and corrosion products from the carrier salt for future disposal. One of the keys to implementing such separation is to develop both online monitoring and processing of the salt. Selecting, justifying, and validating the method to ensure a safe operation is essential for approval by a regulator.
While several methods can be used to separate salt systems from fission products: ion exchange, precipitation, and distillation, in her study, Dr Grebennikova will focus on zeolites' effectiveness in the removal of the most problematic fission products from chloride salts while keeping the change of initial salt composition minimal. The advantage of the proposed method, if successfully implemented, is that the same salt composition can be returned to the reactor vessel.
R.N. Wright, Status of Metallic Structural Materials for Molten Salt Reactors, 2018.
DAWNMANTLE: Decontamination and waste minimisation strategies for and using advanced molten salt nuclear technologies
The DAWNMANTLE project assesses materials requirements that will allow the deployment of advanced molten salt technologies in current decommissioning programmes and across various operations in future nuclear fuel cycles, and determine whether these technologies can provide benefit the nuclear energy sector. This will be achieved by a cradle-to-grave approach by assessing the nature of all materials that come in contact with radioactive material with these approaches and attempting to provide safe and effective waste management options for all waste streams.
Molten salt reactors and pyroprocessing technologies are likely to be key components in future nuclear fuel cycles. The attraction of these technologies can be argued is predominantly based upon the inherent safety imparted by the use of molten salt media (e.g. reduced criticality risk allowing small plant footprints; reduced likelihood of volatile radioactive species formation compared to oxide fuel reactors; plant operation at atmospheric pressures; negligible radiation degradation of molten salt media). These technologies also have the potential to be applied to current and near future decommissioning programmes, such as decontaminating materials and minimizing waste volumes requiring managed disposal. Estimates reported that there is approximately 32,000 tonnes of contaminated intermediate level waste (ILW) stainless steel in the UK alone. At a current predicted rate of ~£70,000/m3 to dispose of ILW, this volume of waste adds up to a considerable cost liability.
Commencing from September 2019, the DAWNMANTLE projected was funded to a level of just under £400,000 (approx. 600,000,000 ₩) and will last until the end of February 2023. The project is comprised of three work packages: WP1, Understanding the degradation and contamination processes; WP2, Decontamination using high temperature MS media; WP3, Treatment approaches for all generated waste streams; and is a continuation of ongoing collaborations between the University of Manchester (UoM), the Dalton Cumbria Facility (DCF) and the University of Sheffield (UoS). The project is led by Dr Clint Sharrad of the University of Manchester (PI) in collaboration with Professor Tim Abrams (UoM), Prof Stuart Holmes (UoM), Dr Aliaksandr Baidak (DCF), and Dr Mark Ogden (UoS) from the UK and collaborators from Ulsan National Institute of Science and Technology (Ulsan, Professor Jaeyeong Park [PI]) and Korea Advanced Institute of Science and Technology (KAIST, Professor Sungyeol Choi [Co-I]) in Korea. The work conducted by Dr Grebennikova here at SNUNFC will directly feed back into the DAWNMANTLE project as part of WP3.
Further Reading:
LIBS online monitoring of molten salt systems: doi.org/10.1016/j.net.2022.07.014
DAWNMANTLE: Grant Notice
Status of Metallic Structural Materials for Molten Salt Reactors: US DoE Report
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