The St. Luci ISFSI with Holtec’s HI-STORM casks installed in the foreground. (Photo: Holtec)
Holtec International has completed a spent nuclear fuel dry storage campaign at NextEra Energy’s St. Lucie nuclear power plant in record time, according to the company. Twelve of Holtec's HI-STORM FW cask systems were loaded to the plant’s independent spent fuel storage installation (ISFSI) in little over a month. In total, 144 used fuel assemblies were moved from St. Lucie’s used fuel pools to the ISFSI pad.
According to Holtec, its Global Site Services unit achieved an average pool-to-pad duration of 2.8 days per multipurpose canister, with the fastest loading completed in 56.15 hours. Each canister contained 37 pressurized water reactor fuel assemblies.
Located in Jensen Beach, Fla., St. Lucie is a 2,136-MWe PWR operated by NextEra subsidiary Florida Power and Light (FPL).
Horizontal to vertical: The dry storage campaign marks St. Lucie’s transition from its legacy horizontal used fuel storage to Holtec’s high-capacity HI-STORM FW system. According to Holtec, the system’s vertically ventilated concrete overpack minimizes the size of the ISFSI and enables efficient cooling through natural convection.
In addition to being able to coax additional storage capacity from the existing ISFSI, the vertical cask system has reduced the site boundary dose by creating a self-shielding cask array configuration and allowed FPL to defer the need for new pad construction by many years, according to Holtec.
Innovations: Holtec added that the St. Lucie project employed several of its latest technological innovations, developed with input from its Holtec User Group. This included a “threadless” remote valve assembly device, an embedded drain line, and a “boltless” mating device.
“These mechanical innovations collectively enhanced safety, reliability, and operational efficiency throughout the St. Lucie loading campaign,” the company said.
