SAFSTOR chosen for Three Mile Island decommissioning

08 April 2019

Exelon Generation has filed its detailed plan for decommissioning unit 1 at Three Mile Island in Pennsyvlania, but says the plant will remain in operation if the state enacts a policy solution to preserve nuclear capacity.

Three Mile Island unit 1 (Image: NRC/Exelon)

The 837 MWe (net) pressurised water reactor is currently scheduled for closure at the end of September.

"Even while we continue to safely operate Three Mile Island at industry-leading levels, we have a responsibility to prepare the plant, along with our community and our employees, for decommissioning," Site Vice President Edward Callan said. "At the same time, we are actively engaged with stakeholders and policymakers on a solution to preserve Pennsylvania's nuclear facilities and the clean, reliable energy and good-paying jobs they provide … However, time is not on our side."

A Post Shutdown Decommissioning Activities Report (PSDAR) must be filed with the US Nuclear Regulatory Commission (NRC) as part of the process to shut down a nuclear power plant. The report must include amongst other things a description and schedule for the planned decommissioning activities and an estimate of the expected costs.

The PSDAR filed by Exelon details the company's selection of the SAFSTOR option for decommissioning the plant, and outlines plans to dismantle large components, including the station's cooling towers, beginning in 2074. SAFSTOR - also known as deferred dismantling - is one of three federally allowed options for decommissioning a nuclear power plant in the USA, the others being DECON (immediate dismantling) and ENTOMB, where radioactive contaminants are permanently encased on site. To date, no NRC-licensed facilities have chosen the ENTOMB route.

"The SAFSTOR option provides a safer environment for our decommissioning workforce by allowing additional time for normal radioactive decay, which results in less waste and lower radiation exposure," Exelon said.

Used nuclear fuel will be transitioned into the on-site used fuel pool and then moved to dry cask storage by the end of 2022, where it will be protected in a hardened facility with multiple layers of structural, human and electronic security. Facility staffing will decrease in three phases from 675 employees in 2017 - when Exelon announced its plans for the plant's premature retirement - to 50 full-time employees in 2022 "absent market or policy reform".

Pennsylvania is home to nine nuclear reactors at five power plants - Beaver Valley, Limerick, Peach Bottom, Susquehanna and Three Mile Island - which together produce nearly 40% of the state's total electricity generation and just over 93% of its zero-emissions energy. FirstEnergy has also announced plans to prematurely retire the two-unit Beaver Valley plant in 2021. Legislation updating the Pennsylvania Alternative Energy Portfolio Standards Act to recognise nuclear energy for its significant contribution to the state's zero-carbon energy production was introduced in the state's legislature in March.

"The current market design fails to properly recognise the significant environmental and resiliency attributes associated with the carbon-free, reliable energy generated at TMI and nuclear plants across the Commonwealth," Exelon said. "Absent action in the coming months by Pennsylvania policymakers, the loss of nuclear plants will increase air pollution, compromise the resiliency of the electric grid, raise energy prices for consumers, eliminate thousands of good-paying local jobs and weaken the state’s economy."

Researched and written by World Nuclear News