Reactor vessel removal completed at Crystal River

12 December 2023

Orano USA, assisted by Netherlands-based heavy lifting company Mammoet have completed removal of the sectioned 540-tonne reactor pressure vessel (RPV) at unit 3 of the shutdown Crystal River NPP in Florida. The removal of the RPV is part of the accelerated decommissioning of the facility.

The 860 MWe pressurised water reactor plant began operation in 1976, and operated for 33 years until shutdown in 2009. It was permanently closed in 2013. Decommissioning was originally expected to take 50 years for completion by 2074, with dismantling starting in 2067. 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.

By 2018, all used fuel had been transferred to an on-site Independent Spent Fuel Storage Installation and in 2020 the US Nuclear Regulatory Commission (NRC) approved transfer of the plant's licence from Duke Energy to Accelerated Decommissioning Partners (ADP - a joint venture between NorthStar Group Services and Orano USA). The Florida Public Service Commission subsequently approved the transaction and ADP began decontamination and dismantlement later in 2020 instead of 2067.

Orano has developed and patented its optimised segmentation (OS) process, which first segments, extracts and separates underwater the RPV 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). This significantly speeds up the decommissioning process.

The A, B, and C internals waste was precisely repacked inside the emptied vertical RPV to optimise the segmentation into three pieces for transportation and disposal. Using a custom-installed strand jack system spanning the inside of the reactor containment building, Mammoet’s team carefully lifted the two heaviest RPV 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.

Orano completed the cutting and conditioning of the RPV and internals in just under two years. This final stage marks the conclusion of the plant's dismantling and used fuel management project, which began in 2021. Orano's Dismantling & Services teams carried out the cutting and conditioning of the reactor vessel and primary circuit components, using the OS process and transported them to the dedicated disposal site in East Texas.

The reactor pressure vessel or RPV, measuring around 10 meters in height and weighing several hundred tonnes, is the largest metal component in a pressurised water reactor. The CR3 decommissioning project has been carried out in “an innovative financial and industrial framework”, involving the transfer of ownership of the used fuel and the operating licence from US utility Duke Energy to ADP, Orano said. Now that the cooling system, RPV, and vessel internals have been removed, the CR3 reactor building has been turned over to NorthStar for demolition.

Jean-Christophe Patout, Senior Executive Vice President in charge of the Orano Group's Dismantling & Services activities, commented: "The completion of this project in such a short timeframe and employing an innovative process, bears testimony to Orano's proficiency in carrying out cleanup and dismantling projects in the United States.

Pierre Marty, Executive Vice-President of Orano DS International Operations and CEO of Orano GmbH, said the "outstanding" performance at Crystal River followed on from work at Vermont Yankee and Orano's experience decommissioning several German sites, including at Brunsbüttel, an 800 MWe boiling water reactor (BWR). "At Orano DS, we share our experiences and best practices across all of our projects to always provide our customers with the accumulated benefits of our lessons learned," he said.

Mammoet's strand jack system lifted, transferred, and then lowered the segmented RPV pieces into the transport and disposal packages at ground level for removal from the reactor building. "Altogether, Mammoet completed the reactor vessel removal with a quicker, more cost-effective, and more efficient solution using the strand jacks' greater lifting power and minimal required space to position the equipment inside an already congested containment area," the company said. Mammoet Project Manager Sidney King said execution of the lifts “were performed flawlessly”. He added: “It is exciting to see the experience, technical expertise, and Mammoet's innovative thinking come together to be a part of this historic moment in nuclear decommissioning."

Image: A strand jack system was used to lift and lower the segmented RPV into the transport and disposal packages at ground level for removal from the reactor building (courtesy of Mammoet)

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