Reactor Decommissioning History
Three Mile Island Unit 2 (TMI-2)
revised 14-FEB-2014

Overview

TMI-2 was a commercial power PWR reactor. It had a generating capacity of 792 MWe and 2772 MWt. It operated from December 1978 to March 1979 when a partial meltdown occurred. Amount of full power days was relatively low. The "TMI-2 Recovery" effort required some internals removal and segmentation to gain access to the bottom of the RV. This work was not called decommissioning since it had not been decided if the reactor would be repaired or not. Post-Defueling Monitoring Storage began December 1993, however approximately 1% of the fuel and debris remains in the reactor vessel and piping. Currently no significant dismantlement is underway. It is planned to be decommissioned after Unit 1 is retired. The Reactor Building is opened once a year for inspections.

Reactor Decommissioning Specifics

Internals Removal
The reactor vessel head was removed in July 1984.

Core boring to segment the Lower Grid Top Rib section was performed during or before 1988.

PCI Energy Services performed segmentation of the Lower Core Support Assembly in 1988 and 1989. This was done remotely underwater using primarily thermal cutting (plasma torch). PCI also claims to have used a Rotary Abrasive Saw (grinder) and Abrasive Water Jet (we have conflicting reports on this). It is believed that some high pressure water cutting was done on core material but only as testing.

Reactor Vessel Removal
Although many metallurgical samples have been removed from the pressure vessel no decommissioning activities have been started to the RV.

Segmentation and Packaging Plan (S&P Plan)
Pre-site (Lower Core Support Assembly): PCI Energy Services; Steve Larson, Paul Tapar.
At site (Lower Core Support Assembly): PCI Energy Services

Key People
George Knetl was the on-site Project Manager for PCI Energy Services.
Jim Byrne was project manager for GPU Nuclear.

Contractors
Bechtel Corp.
PCI Energy Services.
MPR.

Comments
As of 2013 there were publications (WIKI) that the internals are removed. Although we have no source that wishes to be quoted, sections of the Lower Grid Plate and bottom of the Core Barrel are still in place. The only removal was to gain access to the bottom vessel bowl to take the MDM sample. Therefore most of the Lower Internals are still in the Reactor Vessel.

The spare or "back-up" MDM tool used to remove BMI penetration welds was sent to the Smithsonian Museum. This tool never was contaminated.

Numerous companies and projects were on site throughout the recovery of TMI-2. People that were in containment at this time described the atmosphere as that of a "science fair".

Related Publications and Documents
Presentation Nov 2013 D&D Supply Chain Conference.
"Underwater Plasma Arc Cutting in Three Mile Island's Reactor" by M.S. McGough, W.E. Austin, and G.J. Knetl published in the July 1989 Welding Journal.
A 24-minute video "TMI-2 Clean-up Highlights Program" Produced by GPU Nuclear, 1989.

References
Converstations with various individuals up to Nov 2013.
ANS web page public information "The TMI-2 Cleanup: Challenging and Successful" as of 8/14/05.
NRC's "Fact Sheet on Decommissioning Nuclear Power Plants" (web page 8/15/05).
The NRC web page as of 8/12/05.
NRC fact sheet "The Accident at Three Mile Island" from the NRC web page 8/14/05.
Article: "Underwater Plasma Arc Cutting in Three Mile Island's Reactor", July 1989 Welding Journal.
MPR's web page as of 8/12/05.
PCI Energy Services' web page 8/12/05.
Steve Larson interview 8/12/05.
Nukeworker.com web page as of 9/7/04
Jim Byrne correspondence 8/25/06.

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