It will take about another $1.1 billion to completely decommission the Three Mile Island Unit-1 reactor in Pennsylvania, Constellation Energy Generation told the Nuclear Regulatory Commission in a new detailed cost estimate published Wednesday.
The roughly 40-page updated site-specific decommissioning cost estimate for Three Mile Island Nuclear Station Unit-1 (TMI-1), appended to a letter signed by David Helker, Constellation’s senior manager for licensing, was dated March 21. NRC published the document on its website.
Constellation’s predecessor company, Exelon Generation Company, started decommissioning TMI-1 on September 26, 2019. The company planned to put the plant in long-term storage, or SAFSTOR, until 2079, allowing levels of radioactivity to drop before beginning two years worth of work to clear out equipment and buildings and hand the site off to its landowner for unrestricted use.
Also in March’s estimate, Constellation said it would cost roughly $122 million to manage TMI-1’s spent fuel between 2022 and 2041. That’s roughly 20% of the current balance of the plant’s decommissioning trust fund.
In 2022, Constellation got permission from the NRC to use the trust fund for spent fuel management. In July of that year, the company finished building the plant’s Independent Spent Fuel Storage Installation, where the fuel rods the plant burned can be held in dry storage until either the Department of Energy takes custody of it or Constellation can find a centralized interim storage depot to put it.
According to the latest TMI-1 decommissioning cost estimate, spent fuel management costs at the plant were about $28 million in 2022. That is, according to the same estimate, the expected high-water mark for those activities, which should average about $4 million a year through most of the next two decades.
The TMI-1 decommissioning trust fund balance was about $617 million on Dec. 31, 2022, down about $52.5 million from the $670 million the company reported in 2019, according to the updated decommissioning cost estimate delivered to the NRC last week.
