ML20137U245
| ML20137U245 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 04/11/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20137U242 | List: |
| References | |
| NUDOCS 9704160330 | |
| Download: ML20137U245 (3) | |
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UNITED STATES g
j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20666-0001
- ,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.125 TO FACILITY OPERATING LICENSE NO. NPF-3_8 ENTERGY OPERATIONS. INC.
WATERFORD STEAM ELECTRIC STATION. UNIT 3 DOCKET NO. 50-382 l
1.0 INTRODUCTION
i By application dated October 16, 1996, Ente:gy Operations, Inc. (the licensee), submitted a request for changes to the Waterford Steam Electric 3
l Station, Unit 3, Technical Specifications (TSs). The requested changes would l
j change Notation 2 of TS Table 4.3-1 to require adjustment of the linear power level, the core protection calculator (CPC) AT power, and CPC nuclear power 4
signals to match or be greater than the calorimetric calculation if, from 15%
to 80% of rated thermal power (RTP), the difference is less than -0.5% or greater than 10%. At or above 80% RTP, adjustment would be required if the absolute difference is greater than 2%. The other proposed change to Notation 5 of TS Table 4.3-1 would allow a determination of a cycle-dependent shape a
annealing matrix (SAM) or the use of a cycle-independent SAM in the CPCs. The y
staff's evaluation of the proposed request follows.
j 2.0 EVALUATION A daily calibration (heat balance) is currently performed when thermal power is greater than 15% 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 AT power and the CPC nuclear power calculations agree with the calorimetric calculation if the absolute difference is greater than 2%. 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% 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 i
require the CPC calculations to agree within 12% of the calorimetric calculation when thermal power is greater than or equal to 80% of RTP, and to agree within -0.5% to +10% when thermal power is between 15% and 80% of RTP, based on the reduced accuracy of the calorimetric data inputs at low power levels.
l 9704160330 970411 DR ADOCK 05000382 PDR
' Performing a calorimetric calibration when CPC power is less than the calorimetric by more than 0.5% would allow a small tolerance for operator i
convenience and would gain thermal margin relative to the current value of 2.0%.
The wider tolerance of +10% when CPC power is conservatively indicating j
a higher than actual power would minimize the number of required adjustments and yet would allow the CPC to conservatively determine linear power density
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and departure from nucleate boiling ratio (DNBR).
l 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 conservative relative to the plant safety analyses while reducing the required number of adjustments to these power indications at power levels below 80% of RTP.
4 The CPCs rely upon the excore detector signals to trip the reactor in the event of an anticipated operational occurrence (A00) to ensure that the specified acceptable fuel design limits on minimum DNBR and peak linear heat rate are not violated. To do this, each CPC channel synthesizes the core average axial power shape based on three levels of excore detector signals.
The relative excore detector readings are subsequently adjusted within the 1
CPCs by a set of channel dependent shape annealing constants. These SAM constants are typically measured during the reload startup power ascension and installed into the CPC channels.
Incore and excore signal data are taken at i
regular intervals during the initial startup power ascension and the incore data is subsequently processed through a computer code to determine the relative power at the core periphery. An automated data reduction code is then used to verify the data, calculate the SAM constants and determine whether the measured SAM meets a set of review and acceptance criteria to justify its implementation into the CPC channels.
The licensee has proposed to change Note 5 of TS Table 4.3-1 to allow either a determination of a cycle-dependent SAM or verification of the acceptability of a generic SAM to be used in the CPCs. Currently, since the cycle-specific SAM is only measured once during reload startup, the representation has been observed to be less accurate as the cycle progresses and the power shape evolves from a flattened cosine to a saddle shape. The generic SAM would be based on middle-of-cycle data and, therefore, would be more representative of the entire cycle.
If a generic SAM is used, the matrix elements will be validated each cycle during startup testing and must meet the same acceptance criteria as the cycle-specific SAM elements. This ensures that the axial power shapes generated by the CPCs will still remain within the required uncertainties and that the CPCs will trip the reactor so that minimum DNBR and peak linear heat rate are not violated in the event of an A00.
If these criteria are not met, E01 would calculate a cycle-specific SAM to be used in the CPCs.
In response to a staff question, E01 has stated that they normally monitor the CPC synthesized axial shapes quarterly during each cycle to verify the continued acceptability of the CPC axial shape synthesis.
Based on the above facts, the staff finds the use of a generic SAM acceptable.
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Based on the review described above, the staff concludes that the proposed TS changes to revise the tolerance range between the CPC signals and the calorimetric calculation to -0.5% to +10% between 15% and 80% RTP and to a
provide the option to use a generic SAM in the CPCs are acceptable.
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3.0 STATE CONSULTATION
In accord'ance with the Commission's regulations, the Louisiana 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
4 The amendment changes a requirement with respect to installation or use of a i
facility component located within the restricted area as defined in 10 CFR l
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 Comission 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 6575).
1 Accordingly, the amendment meets the eligibility criteria for 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 f
connection with the issuance of the amendment.
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5.0 CONCLUSION
l The Comission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the J
public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Comission's regulations,
,j and (3) the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributor:
L. Kopp l
Date: April 11, 1997 i
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