Client: The Swedish Nuclear Fuel and Waste Management Co (SKB)
- Methodology Development
- Deterministic and Probabilistic Safety Analyses
The Swedish Nuclear Fuel and Waste Management Company (SKB) is responsible for the management and disposal of all radioactive waste from all Swedish nuclear power plants in such a way as to secure maximum safety for human beings and the environment.
SKB is accountable to the Swedish Radiation Safety Authority (SSM) through Safety Analysis Reports (SARs).
Background to the project
SKB manages a system of facilities used to handle collected waste including: a central interim storage facility for spent nuclear fuel (Clab) near Oskarshamn; an encapsulation plant (under construction) where the spent nuclear fuel will be sealed in copper casks before placement in a geological repository; a final repository for short-lived radioactive waste (SFR) in Forsmark; and sea transport using the vessel M/S Sigrid.
In this instance, SKB needed to meet two requirements:
- Renew its Safety Analysis Report (SAR) on the Clab facility
- Produce a preliminary SAR regarding the construction of a new encapsulation plant.
The aim was to show, through detailed analyses, how nuclear safety is established and maintained for the facilities during normal operation, and in the case of disturbances. This provides assurance that life and the environment are protected from radiological accidents.
SKB asked LR’s experts to help design and review the analysis methodologies and then to carry out the analyses. The scope included internal and external events that could pose threats to the facilities; this could be issues arising from the equipment itself, from operating aspects, or from external phenomena (natural or manmade).
The analyses included:
- Internal and external events
- Cooling of spent nuclear fuel
- PSA study on the overall plant response to possible accident sequences
Failing to address this renewal would result not only in non-compliance with the Swedish Radiation Safety Authority’s regulations, but in the long run also pose a threat to continued operation, development of the facilities, and the safe disposal of its nuclear waste.
How Lloyd’s Register helped
The main project challenge was the large scope of work that needed to be delivered and how to best utilise LR’s experts in the most efficient way.
In the case of the encapsulation plant, development of the technical concept was done in parallel, thus we had to adapt to conditions that were evolving continuously.
During the project, LR utilised staff and experts from three locations across Sweden – in total around 10 people were working on the project.
In order to ensure quality and consistency of what was delivered, internal reviewers were appointed, and all deliverables, including review findings, were discussed and addressed before final issues of the different documents were delivered to SKB.
Outcome for the client
The project deliverables included methodologies, analyses and contributions to the Safety Analysis Reports, with our work forming a critical contribution to SKB’s presentation of the safety concepts to the Swedish Radiation Safety Authority.
In addition, the project resulted in the highly valuable growth of, and dissemination of, knowledge within and between both LR and SKB.
- Establish methodologies for the identification and classification of internal, as well as external, events that could lead to radiological accidents.
- Identify, classify and analyse possible internal events, utilising the established methodology.
- Conduct a detailed survey on possible types of external events, and combinations of external events, that could lead to radiological accidents, analyse the facility’s response, and perform a screening analysis.
- Establish a methodology for a Probabilistic Safety Analysis (PSA).
- Conduct a PSA study to characterise possible accident sequences and to quantify the likelihood of accidents.
- Perform flooding analyses.
- Perform analyses on the cooling of spent nuclear fuel.
- Contribute to the Safety Analysis Reports that show how nuclear safety is established for the facilities (by utilising the above-mentioned analyses).