The core debris from the Three Mile Island Unit No. 2 (TMI-2) reactor accident is currently stored at the DOE Idaho National Engineering and Environmental Laboratory (INEEL) in interim wet storage. The storage pool is an aging 1950's vintage, unlined concrete facility. DOE has tasked its INEEL Management and Operating Contractor, Lockheed-Martin Idaho Technology Company, to move the core debris to a safer, above ground, dry storage facility. This task is the first step in positioning this particular waste for future final disposal as well as preparing the fuel pool for eventual decommissioning. Lockheed-Martin Idaho Technology Company contracted with a Newport News Nuclear led team to design, fabricate, build and test an Interim Spent Fuel Storage Installation (ISFSI) based on VECTRA Technologies, Inc. NUHOMS&neg; horizontal dry storage technology. This paper presents the project's status as well as several lessons learned. It covers the design phase; the preparation of a Nuclear Regulatory Commission (NRC) Safety Analysis Report; and an NRC License Application, coordinated by team member Scientech, for an away from reactor ISFSI on a DOE National Laboratory Site. This project is one of the first joint NRC/DOE efforts.

In July of 1979, an accident occurred at the Three Mile Island Unit No. 2 (TMI-2) nuclear power plant which resulted in the destruction and partial meltdown of the nuclear reactor core. The cleanup of the reactor vessel following the accident included placing the core debris into some 344 stainless steel canisters. These canisters were transported during the 1980s to the Department of Energy's (DOE) Idaho National Engineering Laboratory, now designated as the Idaho National Engineering and Environmental Laboratory (INEEL). The canisters were placed in a fuel pool at the INEEL Test Area North (TAN). A number of examinations and experiments were conducted on the debris and several reports document the impact of the accident on the core. All planned examinations are finished, however, and the current INEEL mission is the safe storage of the debris.

The fuel pool in which the debris is stored is a 1950s vintage, single walled pool. Storage of spent nuclear fuel in this pool has been determined by DOE to be a high vulnerability situation particularly because the INEEL is located in the Snake River Basin above the Snake River Aquifer and therefore any in-liquid storage of radioactive materials is undesirable. The pool is not now leaking or deteriorated in any way, it just does not meet current fuel pool design criteria. DOE, with the Department of Defense, has also entered into an Agreement with the State of Idaho to move all spent nuclear fuel stored at INEEL out of Idaho. As a first step in executing this Agreement, DOE has tasked the INEEL operating contractor, Lockheed-Martin Idaho Technologies Company (LMITCO) with moving all spent fuel from wet storage to interim dry storage pending transportation to the national repository. Via competitive bid, LMITCO selected Newport News Shipbuilding (NNS) and its team of VECTRA Technologies and Scientech, Inc. to design and build a turnkey Interim Storage System for the 344 TMI-2 fuel debris canisters.

Newport News Shipbuilding was awarded the contract from LMITCO in November of 1995. The Request for Proposal and the Contract required a dry storage facility, on a DOE site, DOE operated and regulated with a design based on a previously licensed technology. The Newport News team's proposal was based on the NUHOMS&neg; generic dry storage system. The system uses a custom designed Dry Shielded Canister (DSC) holding twelve of the TMI-2 fuel canisters. The DSC is of the standard NUHOMS&neg; spacerplate design. Loading will be done dry in the TAN hot shop using existing handling equipment. Transportation from the pool to the ISFSI will be via the NUHOMS&neg; model MP-187 transportation cask. Storage will be in a modified NUHOMS&neg; Horizontal Storage Module (HSM). The HSM will not require the side air vents due to the low heat load of the 20-year cooled fuel. Also, the HSM floor and walls have been increased in thickness to provide a lower center of gravity and larger footprint required for the seismic design criteria at the INEEL which is higher than for the standard NUHOMS&neg; design.

As noted above, the team's proposed fuel debris storage system was for a DOE regulated system based on the VECTRA generic NUHOMS&neg; system. At the first meeting, however, the DOE stated their intention to apply for a license for the system under the oversight of the US Nuclear Regulatory Commission (NRC). This was noted as a step in the DOE program to seek external regulation of their activities. This was a significant project change and required redirection of the short term critical path. The focus immediately shifted to preparation of a Part 10CFR72 ISFSI License Application with a Safety Analysis Report for the proposed facility. The basic system design concept did not change but some details required in depth review.

Based on lessons learned from past NRC submittals, the team recommended immediate and frequent meetings with the NRC staff to acquaint the NRC with the project and its challenges. Both LMITCO and DOE concurred and a series of meetings were held with the NRC at both general and technical staff levels. In addition, DOE also held policy level meetings on the project with the NRC. In extensive technical meetings, the intended design and licensing parameters were presented and openly discussed. Due to the nature of the fuel debris, the existing packaging design, and the site of the ISFSI, being integral with an existing operating DOE facility, there are many first-of-a-kinds in this project.

The payload is core debris, not fuel assemblies. This presented modeling challenges for the criticality analyses. Similarly the debris storage canisters can not be treated like fuel cladding. Since they are closed bottom, vented cylinders, the impact of possible water in the debris must be addressed. In addition, the project is the first away-from-reactor storage facility submitted for NRC licensing. The NRC provided information and regulatory interpretations and review guidelines for these "new" issues. Their input influenced several design parameters. This early contact focused the design and avoided effort on investigation of potentially unlicensable configurations. Information at this stage pays early project schedule dividends. The exchanges contributed to a license application document which addressed all noted NRC concerns and provide desired technical data on specific critical issues. The NRC accepted the application as ready for review upon its first submittal.

The DOE continues to observe the value of the lesson learned, having frequent contact with the NRC on developing issues. The interface between an NRC regulated facility with a surrounding DOE regulated host site is still a major, fluid issue. The project has designated specific activities which will be regulated by each agency. These are fairly straight forward. However, when the services of the "outside" agency are used to satisfy a regulatory required need of the "inside" agency facility, the interface must be carefully drawn to avoid creating a situation where the outside personnel would have conflicting procedural responses to a situation. DOE here is using their Fort St. Vrain ISFSI license transfer, from Colorado Public Service to DOE, as a source for lessons learned to be applied to the TMI-2 Project for many of these interface issues such as Quality Assurance, Security and Safeguards, etc. The NRC and TMI-2 project technical staffs similarly still meet as necessary to resolve emerging issues.

As stated, the TMI-2 Safety Analysis Report and License Application was submitted and is currently in NRC review. When the first Request for Additional Information (RAI) was received, another lesson learned from previous commercial submittals was applied. DOE and the NRC arranged a meeting between the project team and the NRC reviewers. This was held in December 1997 before the responses to the requests were finalized. Each information request was discussed with the specific reviewer so that the project team member understood the nature of and basis for the information needed. In as many cases as possible, the team provided an example of the data or proposed answer and could obtain direct, face to face feedback on its acceptability. Several responses required only reference to sections of the Application. Other proposed responses however will require modification, redirection and/or data source references to meet the reviewer's needs. The exchange, however, served to avoid non-value added effort.

Several significant lessons learned apply to this project:

1. A multi-organization, multi-location project needs a firm, structured and enforced communication plan. For the TMI-2 Project, a plan was a LMITCO required deliverable. Once the structure was put into place, following it became natural.
2. Similarly, a method of tracking action items to completion among the team members is needed. Input to the action item system was a subcontract requirement for all team members.
3. For NRC regulated projects or facilities, early and frequent interface with the NRC is invaluable. The NRC itself encourages interface and their information can focus your work. The information may cause project redirection, but early redirection is cost effective.
4. For NRC requested actions, request meetings with the specific reviewers as soon as possible. Insure that they have all information to understand the design basis in your submittal and insure that you understand specifically what and why (often more important) they have requested additional information. Be prepared to discuss proposed responses. Misunderstandings at this stage may result in delays and/or additional request cycles.

The NUHOMS&neg; technology has been purchased from VECTRA by Transnuclear, Inc. Included in the pending sale is the Newport News contract for the TMI-2 storage system. Newport News and Transnuclear are actively working the project. The current work includes:

• responding to the NRC Request for Additional Information,
• completion of the design details, and
• procurement of the hardware.

It is planned that site work at INEEL will commence in the spring of 1998. The project goal is to be ready to move the first debris canisters from wet to dry storage in the first quarter of 1999.

The TMI-2 Project is still in progress. The above status is current as of this date. When this paper was initially proposed, it was expected that the project would be further along by this time. A conflict of interest concern delayed the NRC review start and the bankruptcy of the major Newport News subcontractor, VECTRA, slowed progress on design and hardware. Transnuclear Inc. and VECTRA Technologies Inc. obtained court approval for Transnuclear to purchase the NUHOMS&neg; technology. Transnuclear and Newport News have come to agreement to proceed. Between publication of this paper and the conference, several significant events could occur. The presentation will be revised to reflect developments which are material.

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