ML20054G061
| ML20054G061 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/17/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20054G055 | List: |
| References | |
| NUDOCS 8206210039 | |
| Download: ML20054G061 (5) | |
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- -SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION GPU NUCLEAR CORPORATION METROPOLITAN EDIS0N COMPANY
<I PENNSYLVANIA ELECTRIC COMPANY JERSEY CENTRAL POWER AND LIGHT COMPANY DOCKET NO. 50-320 THREE MILE ISLAND NUCLEAR STATION, UNIT NO. 2 Introduction By letter dated April 8,1982, (Reference 1) the licensee requested changes to the Proposed Technical Specifications Appendix A, for Three Mile Island, Unit 2 (TMI-2). The proposed amendment would allow for the movement of individual control or axial power shaping rods for the purpose of obtaining infonnation on core conditions. Presently all rod metaments are prohibited by the require-ments of Proposed Technical Specification Section 3.1.3.1 which states that all control rod drive breakers shall be open.
This section provided assurance that no reactivity changes would be made as a result of rod motion.
However, recovery operations have progressed to the point that more infonnation is needed that can be used to infer the condition of the core for planning subsequent cleanup and recovery operations.
In addition, the axial power shaping rods must be fully inserted into the core and decoupled before the reactor vessel head is removed.
If full insertion cannot be made, special tooling and procedures must be developed before the head can be lifted.
Planning for these special conditions should begin early in the recovery process.
Summary The licensee has requested NRC staff approval to allow for the movement of individual control rods or axial power shaping rods under the requirements of NRC approved operating procedures. The purpose of the movement is to gain 8206210039 820517 PDR ADOCK 05000320 P
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. advanced information on core conditions that may aid in planning the methodology to be used for future recovery efforts.
Also, prior to head removal, it will be necessary to decouple the APSR lead screws.
This can most easily be accomplished if the rods are first fully inserted.
Therefore inserting the APSR's at this time on an individual basis is a step that must be performed sometime during the cleanup. The licensee has requested to do this step now and the staff concurs. The staff has reviewed the potential effects on the core by this movement and finds that reactivity changes are insignificant and will not affect the demonstrated shutdown status of the core. Therefore we find the proposed change acceptable.
Evaluation
- w-L1 By Order of the Director, Office of Nuclear Reactor Regulation, dated February 11, 1980 a new set of formal license requirements were imposed to reflect the post accident condition of the TMI-2 facility.
The order required in section 3.1.3.1 that all control rod drive breakers remain open to prevent rod drive movement.
NRC analysis (Reference 2) has shown that by maintaining a baron concentration of at least 3,000 ppm, which is currently required in Proposed Technical Speciff-cation section 3.1.1.2, that the maximum Keff would be 0.944, providing an adequate shutdown margin.
Even more conservatively, Reference 3 shows that with a baron concentration of 3500 ppm, the core will remain subcritical with References 2 Keff <0.90 in any physically reasonable rearrangement of the fuel.
and 3 assume the absence of all control rods and burnable poisons when calcu-lating the Keff values.
As verified by reactor coolant system sampling, the licensee has consistently been maintaining a boron concentration of approximately l
3800 and thereby assuring even more shutdown margin than required by the recovery l
. technical specifications. Therefore the staff concludes that any single rod movement will have a minimal effect on the required boron ccncentration and shutdown margin.
All control rod mechanism energizing and subsequent movement will be controlled by NRC approval of procedures and accompanying safety reviews for specific tasks being perfonned.
The procedures will limit one mechanism being energized at a time and require upgraded surveillance to assure that no unexpected change in core conditions occurs.
Environmental Considerations We have determined that the change does not authorize a change in effluent types or total amounts nor an increase in power *4e$el and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the change involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 51.5 (d)(4),
that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this change.
Conclusion Based upon our analysis of the shutdown margin for the TMI-2 core relative to the present and required boron concentration, the staff finds that the modiff-cation of proposed Technical Specification Section 3.1.3.1 is acceptable.
The associated bases have also been modified as requested by the issuance.
. We have also concluded, based on the considerations discussed above, that:
(1) because the change does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, it does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Connission's regulations and the implementation of this change will not be inimical to the common defense and security or to the health and safety of the public.
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REFERENCES 1)
GPU Nuclear letter from R.C. Arnold to B.J. Snyder, Director, TMI Program Office; April 8,1982.
Memorandum from Charles R. Marotta, Sr. Criticality and Shielding 2)
Engineer, Division of Fuel Cycle and Material Safety. Office of Nuclear Material Safety and Safeguards, to Norman Haller, Director and Program Analysis; Nonconservative Reference Office of Management X eff of TMI-2 Core as Given in Special Task Force Report," Evaluation of the Cleanup Activities at Three Mile Island, April 1,1980.
Memorandum from Raymond DiSalvo, Probabilistic Analysis Staff, RES, to 3)
Robert Bernero, Director, Probabilistic Analysis Staff, RES; TMI-2 Hazard Evaluation, April 4,1980.
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