SKB: Protecting a nation from nuclear waste

Client challenge

The Swedish Nuclear Fuel and Waste Management Company (SKB) is responsible for managing and disposing of the radioactive waste from Sweden’s nuclear power plants in a safe way.

To achieve this, SKB operates a system of facilities that include: a central interim storage facility for spent nuclear fuel (Clab) near Oskarshamn; a final repository for short-lived radioactive waste (SFR) in Forsmark; and the vessel M/S Sigrid for sea transport. Our client also plans to construct a deep geological repository in Forsmark for final disposal of spent nuclear fuel and expand Clab with an encapsulation plant, where the fuel assemblies will be sealed in copper canisters before placement in the deep geological repository.

SKB wanted our help in their work to:

• renew the Safety Analysis Report (SAR) for the Clab facility
• produce a preliminary SAR to support construction of the 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 people and the environment are protected from radiological accidents.

How we helped

Our support covered the design and review of SKB’s analysis methodologies and then carrying out the analyses. The project’s scope included internal and external events that could pose threats to the facilities; this encompassed events caused by equipment issues or operating aspects, as well as those caused by natural or manmade external phenomena. We also conducted a probabilistic safety analysis study on the overall plant response to possible accident sequences. For the planned encapsulation plant, our work was done in parallel with development of the technical concept. As such, we had to adapt to the conditions that were evolving continuously.

Ten of our experts from three locations in Sweden supported the project. To ensure quality and consistency of work, internal reviewers were appointed. All deliverables, including review findings, were discussed and addressed before final issue of documents to our client.

Key services

• Establish methodologies for the identification and classification of internal and external events that could lead to radiological accidents.
• Identify, classify and analyse possible internal events, using the established methodologies.
• 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.
• Conduct a probabilistic safety analysis 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 SARs that show how nuclear safety is established for the facilities (using the above analyses).

Client Benefits

Our methodologies, analyses and contributions to the SARs formed a critical part of SKB’s presentation of safety concepts to the Swedish Radiation Safety Authority. In addition, the project introduced valuable new knowledge across our client’s organisation.