Twenty-two years earlier, on March 28, 1979, a combination of equipment malfunctions, operator errors, and design problems resulted in the worst nuclear accident in U.S. history.

Since the day of the accident, INL employees and facilities have assisted in a number of ways, including supporting recovery from the accident, investigation of the causes, removal of damaged core materials and nuclear fuel, and shipment of the materials to the INL for temporary storage until a permanent repository is available.

Soon after the accident, a team of scientists and engineers from the INL flew to the Three Mile Island nuclear plant to assist with investigation and recovery from the accident. This small group eventually grew into a group of nearly fifty INL employees who provided technical assistance with all aspects of recovery from the accident, including the removal and shipment of damaged spent nuclear fuel and core debris to the INL.

INL workers assisted in the development of several new waste handling and waste examination techniques, including: computer models for determining the extent of fuel damage; a drill bit for boring through metals and ceramics to take samples of the melted materials; and a system to remove potentially combustible gasses from filters used to extract radioactive materials from half a million gallons of contaminated water.

From July 1986 until May 1990, shipping casks holding the damaged fuel and core debris were sent by rail car to the INL. In all, 49 casks were sent in 22 shipments, each arriving safely and without incident. Upon arrival at the INL, the shipping casks were transferred to the Test Area North (TAN) facility for cooling and storage.

In 1995, the Settlement Agreement between the State of Idaho and the Department of Energy stipulated removing the TMI debris from the aging storage pool at TAN and placing it in a Nuclear Regulatory Commission-licensed dry storage facility located within INTEC. Complying with the agreement involved moving the debris canisters from wet to dry storage canisters, shipping the canisters to INTEC inside specialized shipping casks, and storage at the Independent Spent Fuel Storage Installation—an NRC licensed facility comprising thirty concrete horizontal storage modules.

The delivery of the final TMI canister to dry storage at this installation on April 20, 2001 beat the date specified in the Settlement Agreement by about two weeks.

The Settlement Agreement requires the TMI debris to be removed from Idaho by January 1, 2035, and placed in a permanent geological repository. On January 10, Secretary of Energy Spencer Abraham notified Nevada authorities that he intends to recommend the Yucca Mountain site to President Bush as being suitable for development as the nation's long-term geological repository for nuclear waste. However, even with this recommendation, the earliest that Yucca Mountain would be ready to accept nuclear waste is 2010.