ML20080F802
| ML20080F802 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/27/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080F797 | List: |
| References | |
| NUDOCS 8402130158 | |
| Download: ML20080F802 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION 3
E WASHINGTON, D. C. 20555
, ~r SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO ISSUANCE OF AMENbMFNT NO. 91 TO DPR-65 NORTHEAST NUCLEAR ENERGY COMPANY, ET AL.
MILLSTONE NUCLEAR POWER STATION, UNIT 2 DOCKET N0. 50-336 1.0 Introduction and Background By [[letter::B10987, Forwards ASME Section Iii,Class 2 & 3 & ANSI B31.1.0 Piping Analysis, Ultrasonic Indications in Steam Generator Top Head Dome Weld. Evaluation Verified Structural Integrity of Plant Steam Generators,Per NRC|letter dated December 30, 1983]], the USNRC issued Amendment No. 90 to Facility License No. DPR-65 for Millstone Nuclear Power Station, Unit 2.
This amendment reflected changes to the Technical Specifications necessary for plant operation in Cycle 6.
T As part of of these changs, the total planar peaking factor F monitoring limits were restored isack to the original Beginning of Cycle (56C) 5 values.
The Cycle 6 licensing analyses supported the proposed revision.
The plant was made critical for Cycle 6 operation on January 5,1984. Core power was increased to levels at which peaking factors could be measured on January 13, 1984.
Subsequent measurements of peaking factors indicated that full power opera-tion would not be possible with the current technical specifications. While the curve is des 1 ned to closely bound actual plant operations the calcu-9 lated value for F was approximately 4.3% too low.
To correct this deficiency in the current technical specifications, Nortn-east Nuclear Energy Company, (the licensee) has provided an application for a license amendment dated January 20, 1984 and supplemented January 25, 1984.
This license amendment would revise total planar peaking factor curve as a function of allowable fraction of rated power.
In addition, the application for amendment requested a revised curve for axial shape index. The purpose of the revised curves is to assure that linear heat rate surveillance requirement can be provided by the excore detectors when the incore system is inoperable.
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2.0 Evaluation T
The total planar peaking f actor F is used to determine the local power density. Local power density is EYlimiting system parameter to protect the fuel from axial power maldistributions, and assure acceptable fuel behavior T
in loss-of-coolant accidents. Because this modification to F is slight,
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the local power density trip setpoint remains unchanged.
8402130158 840127 PDR ADDCK '05000336 P
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',o When the incore monitoring system is operable, direct measurement of power density assures compliance with the 15.6 kw/ft limits of Section 3.2.1.
T The proposed revision of the total planar peaking factor F curve is only of concern when the excore detectors are used to monitor lIXear heat rate.
T$elicenseehasproposedtoconservativelyoffsetthe4.3%increasein F
at full power with a 5.0% decrease in the axial shape index limits. The xrefised limits require that reactor power will be reduced to 95% of allowable rated power when the incore detectors are inoperable. An additional 2%
correction is made to remove an unneeded general tilt allowance.
W9 conclude that this approach for revising the total planar peaking factor l
F curves is conservative. This is because under all circumstances the lirYiiting parameter, local power density, is not exceeded nor are limiting safety system settings varied from previously approved values. We there-fore find these changes acceptable.
3.0 Technical Specification Changes The technical specification changes proposed by the licensee are acceptable as follows:
T A.
Revised total planar peaking factor F curve - This change affects pages 3/4 2-6 anu 3/4 2-8.
The allowIEle total planar peaking factor is increased by 6.3% in the range 0.925 to 1.000 of allowable fraction of rated power. The previous curve has been extended to 0.650 of rated power based on the Cycle 6 reload and safety analyses. The curve has also been corrected by 2% for the unneeded tilt allowance.
B.
New Axial Shape Index Tent - This change to page 3/4 2-4 involves a trurication of the current axial shape index tent at 95% power. This 5% reduction offsets the changes to the total planar peaking factor.
Reactor operation above 95% of rated power is not acceptable if the incore detector system is inoperable.
4.0 Eval;;ation of Emergency Conditions The licensee has requested expedited consideration of this amendment request since the current Technical Specifications result in a derating of the facility. The licensee has stated that discovery of such a small under prediction in the total planar peaking factor was only possible as of January 13, 1984.
The current technical specificaticas supporting Cycle 6 operations aye based on the fuel vendor's predictions of core physical parameters. The F curve was designed to bound as closely as possible the operating characteriltics predicted by the reload analyses.
After completing startup testing and steam generator cleanup, power levels of 30% and greater were achieved on January 13, 1984. At that time, neasurements
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T of F were possible and evidence of the underprediction in F was identified.
The ITcensee could not have identified this situation until power levels in excess of 20% were achieved. At that time the licensee reevaluated the power distribution data and requested this proposed amendment.
The staff concludes that failure to act in a timely manner would result in a continued derating of the plant and therefore the emergency provisions of 10 CFR 50.91(a)(5) are applicable to this situation. The staff concludes that the licensee's request under these provisions is acceptable, and that an amendment should be issued under the emergency provisions.
5.0 Conclusions We have reviewed the proposed changes to the Millstone Unit 2 Technical Specifications and find they are acceptable. We find that the licensee has provided an acceptable basis for this amendment to be issued under the emergency provisions of 10 CFR 50.91(a)(5).
5.1 Environmental Consideration We have determined that the amendment does not authorize a change in effluent l
types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendment involves an action which is in-significant from the standpoint of environmental impact and, pursuant to 10 CFR 651.5(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 amendment.
5.2 Conclusion We have concluded, based on the considerations discussed above, that:
(1) there is reasonabie assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: January 27, 1984 Principal Contributors:
K. Heitner, DL M. Dunenfeld, CPB P
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