Abstract
Small modular reactors (SMRs) are being considered in Finland for the production of low car-bon electricity and heat. Siting of the reactor facilities and management and disposal of the spent fuel and low- and intermediate level waste play an important role in the safe and sustainable deployment of SMR technology. The deployment process and waste management are guided by a regulatory framework, currently being updated in Finland. In addition, other factors such as applicability of current waste management methods and societal acceptability have an important role in this process.
SMR Siting and Waste Management (SMRSiMa) is a coordinated project between VTT and Geological Survey of Finland (GTK) focusing on waste management of spent nuclear fuel produced in an SMR and in the siting and societal acceptability of an SMR plant and repository. In 2022, SMRSiMa received funding from both the SAFIR2022 and KYT2022 programmes. The work presented in this report focuses on topics linked to the regulatory framework, effect of SMR reactor design and spent fuel properties on waste management and on societal acceptability factors. SMR plant and repository siting is discussed separately
in a report by GTK.
The characteristics of the spent nuclear fuel (SNF) play a crucial role in adapting the current disposal methods for SNF produced in a SMR. The method currently in use in Finland (KBS-3V) was originally designed solely for UO2 fuel with specific fuel characteristics. Adapting the method for SMR waste requires that the characteristics of the SNF are defined to a highly
de-tailed level, including discharge burnup, decay heat power, photon emission rate (gamma radiation), mobile nuclide concentration, chemical characteristics and post-irradiation reactivity linked to criticality safety. For SMR designs based on current LWR technologies, the spent fuel may differ from that of existing, large LWRs due to the smaller size of the SMR core
potentially leading to higher neutron leakage and in other reactor and fuel parameters (e.g., enrichment of the fuel). This report compares some of these basic parameters for number of LWR-SMRs potentially relevant for Finland.
In order to quantify spent fuel characteristics, preliminary 2D calculations were made with two different example reactors (NuScale Power ModuleTM and Finnish heating reactor design LDR-50) with the continuous-energy Monte Carlo code Serpent in the previous phase of the project (Keto et al. 2022). Based on the 2D calculations, the main differences between the SMR
and NPP spent fuels was linked to lower burnups in the SMRs. Considering waste management, the lower levels of decay heat and ionizing radiation could make the handling of the waste less demanding. However, 3D calculations were needed to determine the effect of the smaller SMR core size and to address further the potential uncertainties remaining with criticality safety. During 2022, Serpent 3 D calculation were made considering the LDR-50 reactor. Preliminary data shows some difference between the 2D and 3D cases, but since the calculations were per-formed with the start-up core, the results are notfully representative with respect to the total anticipated spent fuel inventory. Furthermore, due to difficulties linked with the heavy calculation process and difficulties in interpretation of the data, the presented results are rather coarse even with the model limitations. Calculations are continued within the next phase of the project.
Considering an SMR that would be utilised for district heating purposes, the location of the site would be closer to a city than normal NPPs. This brings challenges considering the siting from the geological perspective, but also from societal acceptability point of view. Early engagement of stakeholders, civil society and public is required for successful SMR deployment and waste management.
SMR Siting and Waste Management (SMRSiMa) is a coordinated project between VTT and Geological Survey of Finland (GTK) focusing on waste management of spent nuclear fuel produced in an SMR and in the siting and societal acceptability of an SMR plant and repository. In 2022, SMRSiMa received funding from both the SAFIR2022 and KYT2022 programmes. The work presented in this report focuses on topics linked to the regulatory framework, effect of SMR reactor design and spent fuel properties on waste management and on societal acceptability factors. SMR plant and repository siting is discussed separately
in a report by GTK.
The characteristics of the spent nuclear fuel (SNF) play a crucial role in adapting the current disposal methods for SNF produced in a SMR. The method currently in use in Finland (KBS-3V) was originally designed solely for UO2 fuel with specific fuel characteristics. Adapting the method for SMR waste requires that the characteristics of the SNF are defined to a highly
de-tailed level, including discharge burnup, decay heat power, photon emission rate (gamma radiation), mobile nuclide concentration, chemical characteristics and post-irradiation reactivity linked to criticality safety. For SMR designs based on current LWR technologies, the spent fuel may differ from that of existing, large LWRs due to the smaller size of the SMR core
potentially leading to higher neutron leakage and in other reactor and fuel parameters (e.g., enrichment of the fuel). This report compares some of these basic parameters for number of LWR-SMRs potentially relevant for Finland.
In order to quantify spent fuel characteristics, preliminary 2D calculations were made with two different example reactors (NuScale Power ModuleTM and Finnish heating reactor design LDR-50) with the continuous-energy Monte Carlo code Serpent in the previous phase of the project (Keto et al. 2022). Based on the 2D calculations, the main differences between the SMR
and NPP spent fuels was linked to lower burnups in the SMRs. Considering waste management, the lower levels of decay heat and ionizing radiation could make the handling of the waste less demanding. However, 3D calculations were needed to determine the effect of the smaller SMR core size and to address further the potential uncertainties remaining with criticality safety. During 2022, Serpent 3 D calculation were made considering the LDR-50 reactor. Preliminary data shows some difference between the 2D and 3D cases, but since the calculations were per-formed with the start-up core, the results are notfully representative with respect to the total anticipated spent fuel inventory. Furthermore, due to difficulties linked with the heavy calculation process and difficulties in interpretation of the data, the presented results are rather coarse even with the model limitations. Calculations are continued within the next phase of the project.
Considering an SMR that would be utilised for district heating purposes, the location of the site would be closer to a city than normal NPPs. This brings challenges considering the siting from the geological perspective, but also from societal acceptability point of view. Early engagement of stakeholders, civil society and public is required for successful SMR deployment and waste management.
Original language | English |
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Publisher | VTT Technical Research Centre of Finland |
Number of pages | 30 |
Publication status | Published - 31 Jan 2023 |
MoE publication type | D4 Published development or research report or study |
Publication series
Series | VTT Research Report |
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Number | VTT-R-00040-23 |
Keywords
- SMR
- spent fuel
- waste management
- barriers