On behalf of Orano USA, Mammoet lifted and removed a 540-tonne nuclear reactor vessel (RV) at the Crystal River Unit 3 pressurised water reactor site in Florida.
The removal of the RV is part of the accelerated decommissioning of the facility, which began generating electricity in 1977.
Typically, during decommissioning, all parts of a nuclear reactor are segmented, packaged, and shipped in up to 80 transports, which is time and cost-intensive with repeated processes and regulatory requirements, Mammoet explained. Orano, however, developed and patented a process known as ‘optimised segmentation’. This segments, extracts and separates the RV’s internal components into categories based on their radioactivity using the US Nuclear Regulatory Commission’s low-level waste classification system: A, B, C, greater-than-class-C (GTCC).
The A, B, and C internals waste was repacked inside the emptied vertical reactor vessel to optimise the segmentation of the entire RV into three pieces for transportation and disposal. Using a custom-installed strand jack system spanning the inside of the reactor containment building, Mammoet’s crew carefully lifted the two heaviest RV segments out of the reactor well and then lowered each one down through the reactor building into a customised package on the ground level for transport to final disposal.
Mammoet’s team had prior knowledge of the facility after previously completing a steam generator replacement at the same location. This knowledge, combined with early involvement with Orano to plan the process and provide a workable solution for handling the reactor parts, was crucial to execution using the optimised segmentation method. This project marks the first time that this method was performed, said Mammoet.
