Orano's team cut up the reactor vessel internals underwater and categorised them based on radioactivity. Those that were classed as Greater-than-Class-C - one of the four classes of low-level radioactive waste according to the US Nuclear Regulatory Commission's waste classification system - were separated and packaged for long-term storage onsite. The remaining low-level radioactive waste was then repacked into the vessel in a precise arrangement to optimise the transportation and cost-effectiveness of disposal.
The repacked and drained vessel - still in its original vertical orientation in the reactor vessel cavity - was then filled with an engineered grout that hardened and transformed the reactor vessel and internals into a single, solid mass. It was cut horizontally, straight through the steel reactor vessel, solidified grout and internals, using a diamond wire saw. The cut piece was then lifted from the reactor vessel cavity and transferred into a custom-built package, which was filled with grout to immobilise the contents before welding it shut in preparation for transportation for final disposal.
"On task, on time, on budget, and safely cutting out and packaging an irradiated 246-ton chunk of steel and material - I am proud of our team's performance and focus," Orano USA CEO Amir Vexler said.
The packaged segment is transferred to an on-site storage facility (Image: Orano)
Crystal River 3, a single unit pressurised water reactor in Florida, began commercial operation in 1977, but complications concerning the reactor's containment structure following steam generator replacement work in 2009 led to its permanent closure. In 2020, owner Duke Energy announced plans for accelerated decommissioning, and contracted Accelerated Decommissioning Partners - a joint venture between NorthStar Group Services and Orano USA - to begin decontamination and dismantlement of Crystal River 3 in 2020 instead of 2067 as originally planned.
Reactor dismantling operations started in 2021, and the accelerated decommissioning timeline will see all decontamination and decommissioning work completed, and the demolition of all the plant's structures - except the dry cask storage facility holding its used nuclear fuel - by 2027.
