Holtec has announced that the Palisades NPP has successfully completed passivation of its primary system, which is an essential step to ensure long-term equipment reliability and a key milestone in the ongoing effort to return the plant to service.
Palisades, an 800 MWe single-unit pressurised water reactor, ceased operations in May 2022 and was defuelled the following month, despite being licensed to operate until March 2031. The unit’s licence was transferred from operator Entergy Nuclear Operations to Holtec Decommissioning International and Holtec Palisades for decommissioning. However, in late 2023, Holtec began the process of obtaining licensing approvals return the plant to operational status for the remainder of its licensing term.
To perform passivation, the Palisades team brought the primary system to normal operating temperature and pressure for the first time since the plant was shut down in 2022. Establishing and maintaining these conditions allowed for precise control of water chemistry and restoration of the system’s protective surfaces following extensive maintenance, inspection, and component upgrades completed over the past two years.
This builds on significant restoration efforts across the primary system, including steam generator tube repairs, pressure boundary weld restorations, and a first-ever comprehensive system cleaning that significantly reduced dose rates in sensitive areas of the plant.
With passivation complete, the system will now be cooled and prepared for additional testing, equipment upgrades, and preparations for fuel loading. Additional activities underway include upgrades to the fuel handling system, switchyard restoration work, completion of required surveillances, and final closeout of major maintenance evolutions. Other recent accomplishments include completing more than 300 inspections of piping and welds, as well as reinstalling the main turbine generator.
“The completion of primary system passivation reflects the diligence and technical rigor our team is bringing to position the plant for safe, reliable operation for decades,” said Holtec International President Kelly Trice. “Ensuring long-term safety and reliability remains the central focus of our restart mission, and we continue to execute this work with the care and precision it warrants.”
Plans to restart Palisades by the end of 2025 were postponed to the first quarter in 2026. The apparent reason for the delay was continuing work on the steam generating system. In 2024 the inspection of the steam generator found that a large number of the tubes had defects including cracks in them. Holtec’s corrective action involved inserting sleeves in the damaged tubes which addressed the problem.
Holtec is advancing plans for the future deployment of its Pioneer 1 and 2 SMR-300 units at the Palisades site in collaboration with Hyundai E&C and Mitsubishi Electric. The planned two-unit small modular reactor project is expected to provide an additional 680 MWe to complement output from the restarted Palisades plant.
