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 this week.
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 Wednesday 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.
Meanwhile, DOE has no plans to take custody of spent fuel from any power plants, nor any plans to build a permanent geologic repository at the congressionally authorized site of Yucca Mountain in Nye County, Nev.
A pair of commercial companies, Holtec and Interim Storage Partners, have proposed building interim spent fuel depots in New Mexico and Texas, respectively, that could if built handle much of the current U.S. inventory of stranded nuclear fuel. However, those sites face strong opposition from the governments of their hosts states.
However, with neither the government nor commercial facilities in existence today, Constellation also sent to the NRC last week an updated TMI-1 spent fuel management plan. In the plan, Constellation essentially made its best guess about when DOE might start taking custody of spent fuel.
This year, the best guess was 2035, five years later than the projection the company included with its 2019 TMI-1 decommissioning cost estimate. If DOE does start taking custody of fuell in seven years time, that would put TMI-1 in line to have its spent fuel collected by the federal government by the end of 2041, Constellation estimated. That assumes DOE sticks to its plan to begin collection with the fuel that’s been out of a reactor the longest.
The current politically appointed head of DOE’s Office of Nuclear Energy has said the agency might, if Congress changes existing law, be able to build a federally owned interim spent fuel storage facility in the 2030s.
