US EnergySolutions subsidiary ZionSolutions has completed the sixth year of decommissioning work at the Zion NPP on budget and ahead of schedule, the company announced on 28 October. Zion's two pressurized water reactors (PWRs) on the shores of Lake Michigan were permanently shut down in 1998 for economic reasons after just over 20 years of operation. In 2007, owner Exelon contracted EnergySolutions to dismantle the plant, ship the waste to its disposal site in Utah, and return the Illinois site to greenfield status over 10 years. EnergySolutions said the decommissioning effort is currently 88% complete and several years ahead of the original 10-year schedule, which will mean a lower overall decommissioning cost.
The work began in 2010 after the plant's licence and decommissioning funds were transferred to EnergySolutions. The site will be returned to Exelon about 2020. Used fuel will remain on site in dry cask storage at an independent used fuel storage installation, known as an ISFSI, until a federal repository is available to receive the fuel.
The last of the plant's large components were removed from the site in March. Large components include steam generators, pressurizers, piping components, reactor coolant pumps and motors. Demolition of the turbine hall is now nearing completion, after which dismantlement of the containment buildings will begin.
Achievements claimed by the project to date include the design and construction of the most modern and largest ISFSI for decontamination and decommissioning (D&D); a world record for the transfer of used fuel to the ISFSI of 366 days; an "industry first" in the successful segmentation, removal, transportation and disposal of both reactor vessels; and completion of the D&D industry's largest and most efficient major component removal and disposal project. Furthermore, projections indicate nearly a three-fold reduction in overall worker exposure compared with the previous industry best performance, the company said.
EnergySolutions president Ken Robuck said more than 98% of all the radioactive source term of the plant has now been removed. "Additionally, we anticipate a significant reduction in financial assurance requirements in early 2017 due to the accelerated completion schedule and our on-going successful performance of the project," he said.