Risk-benefit analysis of thermal property measurement strategies for ONKALO® facility
Kiuru, Risto (2023)
2023
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2023122138894
https://urn.fi/URN:NBN:fi:amk-2023122138894
Tiivistelmä
This report describes a thesis with research-based development work with characteristics of constructive research combined with design. It aimed at developing and evaluating a variety of thermal property measurement strategies for Posiva Oy’s ONKALO® final disposal facility for spent nuclear fuel. It is a part of a larger project on the thermal performance of the facility. The goal of the work was to determine the most suitable measurement strategy. Results of the development work will be used by Posiva Oy as a basis for creating a program for thermal conductivity measurements during the operation of the facility.
Goals of the process were analysed, and research was conducted to establish context and understanding of the target organisation, the disposal of spent nuclear fuel, the safety considerations, regulatory environment, and the ONKALO® facility. This was done through discussions with the client, pitching the topic and creating a topic analysis, and document analysis. Next, goals and constraints of the strategies were specified through a semi-structured interview combined with an open-ended interview, and content analysis of the results. Results of the interview were utilised to help develop the methodology and identify key characteristics for the strategies. Risk assessment, assessment of benefits, and a customised risk-benefit analysis developed for this work were carried out to evaluate the developed strategies and to identify the most suitable strategy candidate.
A methodology for the risk-benefit analysis of thermal property measurement strategies was developed. To allow quick visualisation of the risks and benefits of each alternative, a new tool in the form of a risk-benefit matrix was created. Based on the risk-benefit analysis, it could be concluded that in situ testing cannot be recommended and that there is no time pressure for thermal property measurements. It was also concluded that to get a comprehensive understanding of the rock mass, all pilot holes should be considered for sampling, and sampling should be done in a targeted fashion. Best strategy candidate appears to be targeted laboratory testing where all pilot holes are considered for sampling, and a statistically sufficient number of samples are taken per target of interest.
Goals of the process were analysed, and research was conducted to establish context and understanding of the target organisation, the disposal of spent nuclear fuel, the safety considerations, regulatory environment, and the ONKALO® facility. This was done through discussions with the client, pitching the topic and creating a topic analysis, and document analysis. Next, goals and constraints of the strategies were specified through a semi-structured interview combined with an open-ended interview, and content analysis of the results. Results of the interview were utilised to help develop the methodology and identify key characteristics for the strategies. Risk assessment, assessment of benefits, and a customised risk-benefit analysis developed for this work were carried out to evaluate the developed strategies and to identify the most suitable strategy candidate.
A methodology for the risk-benefit analysis of thermal property measurement strategies was developed. To allow quick visualisation of the risks and benefits of each alternative, a new tool in the form of a risk-benefit matrix was created. Based on the risk-benefit analysis, it could be concluded that in situ testing cannot be recommended and that there is no time pressure for thermal property measurements. It was also concluded that to get a comprehensive understanding of the rock mass, all pilot holes should be considered for sampling, and sampling should be done in a targeted fashion. Best strategy candidate appears to be targeted laboratory testing where all pilot holes are considered for sampling, and a statistically sufficient number of samples are taken per target of interest.