Year
2014
Abstract
According to plan, less than a decade is left for the first underground repository for spent nuclear fuel to start operation in the Olkiluoto peninsula of Finland. To serve the operation of the geological repository, an over-ground encapsulation facility will be constructed above the repository with the aim of receiving the spent fuel assemblies and packing them in groups into copper canisters that are eventually emplaced in the underground repository. The safeguarding of the encapsulation plant of the Finnish final disposal project is, in the short term, posing more safeguards challenges and constraints than the underground repository itself. The involved stakeholders (operator, designers, national authorities, international inspectorates) have engaged since more than five years into a dialogue on the requirements and measures needed for safeguards at the encapsulation facility. The initial envisaged solution for the last verification measurement of each fuel assembly was to perform the measurement late in the process at the handling cell of the encapsulation plant. This option was based on the assumption of the availability of a high accuracy measurement method like the Passive Gamma Emission Tomography (PGET) that would be able to detect the absence of a single pin from the assembly. However, given that it cannot be guaranteed that a fully developed and tested PGET system will be available for use in the early 2020s the international safeguards inspectorates had to define their baseline safeguards requirements on the current ‘best internationally available means’ for the verification. As a result the current thinking for the measurement of the spent fuel content is to take place in the cooling ponds of the power plants and then maintaining the continuity of knowledge all the way until the packing inside the copper canisters at the encapsulation plant. This paper provides more detail of the realistic and flexible safeguards strategy currently under development.