ML20138J717
| ML20138J717 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/05/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20138J715 | List: |
| References | |
| NUDOCS 9705080305 | |
| Download: ML20138J717 (3) | |
Text
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UNITED STATE 8 1
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NUCLEAR REGULATORY COMMISSION
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f-SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION f
j RELATED TO AMENDMENT NO.183 T0 t
FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY.0PERATIONS._INC.
8 ARKANSAS NUCLEAR ONE. UNIT NO. 2 4
DOCKET NO. 50-368 l
1.0 INTRODUCTION
By [[letter::05000313/LER-1996-010-02, :on 961119,failed to Test Reactor Protection Sys (RPS) High Temp Trip Function.Caused by Inadequate Procedure Rev.Declared RPS Inoperable,Revised RPS Test Procedures & Tested All Four Channels|letter dated December 19, 1996]], Entergy Operations, Inc. (the licensee) submitted a request for changes to the Arkansas Nuclear One, Unit No. 2 (ANO-2) Technical Specifications (TS). The requested changes would change Notation 2 of TS Table 4.3-1 to require adjustment of the linear power level, the core protection calculator.(CPC) delta T power, and CPC nuclear power signals to match or be greater than the calorimetric calculation if, from 15 l
percent to 80 percent of rated thermal power (RTP), the difference is less than -0.5 percent or greater than 10 percent. At or above 80 percent RTP, adjustment would be required if the absolute difference is greater than 2 percent. The staff's evaluation of the proposed request follows.
2.0 EVALUATION 1
A daily calibration (heat balance) is currently performed when thermal power I
is greater than 15 percent of RTP.
In accordance with Note 2 of TS Table 4.3-1, the calibration consists of adjusting the linear power level signals and the CPC addressable constant multipliers to make the CPC delta T power and the CPC nuclear power calculations agree with the calorimetric calculation if the absolute difference is greater than 2 percent..These checks and, if necessary, the adjustment of the linear power level signal and the CPC addressable constant coefficients, are made to ensure that the accuracy of these CPC calculations is maintained within the analyzed error margins. The power level must.be greater than 15 percent RTP to obtain accurate data since the accuracy of the calorimetric data is questionable at lower power levels.
In order to reduce the number of adjustments required as the power level increases, the licensee has proposed to change Note 2 of Table 4.3-1 to require the CPC calculations to agree within 12 percent of the calorimetric calculation when thermal power is greater than or equal to 80 percent of RTP, and to agree within.-0.5 percent to +10 percent when thermal power is between 15 percent and 80 percent of RTP, based on the reduced accuracy of the calorimetric data inputs at low power levels.
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. Performing a calorimetric calibration when CPC power is less than the calorimetric by more than 0.5 percent would allow a small tolerance for operator convenience and would gain thermal margin relative to the current value of 2.0 percent. The wider tolerance of +10 percent when CPC power is conservatively indicating a higher than actual power would minimize the number of required adjustments and yet would allow the CPC to conservatively determine linear power density and departure from nucleate boiling ratio.
The staff has determined that these proposed changes to Note 2 of TS Table 4.3-1 are acceptable because they ensure that the power indications are l
conservative relative to the plant safety analyses while reducing the required number of adjustments to these power indications at power levels below 80 percent of RTP.
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Based on the review described above, the staff concludes that the proposed TS changes to reviso the tolerance range between the CPC signals and the calorimetric calculation to -0.5 percent to +10 percent between 15 percent and 80 percent RTP are acceptable.
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3.0 STATE CONSULTATION
In accordance with the Comission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a pro-posed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (62 FR 4348). Accordingly, the amendment meets the eligibility criteria for i
categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
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5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, i
that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such i
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activities will be conducted in compliance with the Commission's regulations, i
and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
T. Polich Date: May 5,1997 i
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