ML18011A525
| ML18011A525 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 07/27/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18011A524 | List: |
| References | |
| NUDOCS 9408080040 | |
| Download: ML18011A525 (8) | |
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'NITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 20555-0001 SAFETY VA UATION BY TH OFFICE OF NUC EAR REACTOR REGULATION RE ATED TO AMENDM NT NO.
50 TO FACI ITY OPERATING LICENSE NO.
NPF-63 CAROLINA POWER
& LIGHT COMPANY-SHEARON HARRIS NUC R
0 R PLA T U
DOCK T NO. 50-400
- 1. 0 INTRODUCTION By letter dated May 11, 1994, Carolina Power 5 Light Company (the licensee) submitted a request for changes to the Shearon Harris Nuclear Power Plant, Unit 1, Technical Specifications (TS).
The proposed amendment would establish limits on reactor power level as a function of total reactor coolant system (RCS) flow rate up to 5 percent below the current flow rate.
Specifically, the licensee proposes that the rated power be reduced by 1.5 percent for each 1.0 percent that the RCS flow is less than the required minimum flow at rated thermal power.
The 1.5 percent power to 1.0 percent flow ratio was provided to the licensee in an April 22, 1994, letter by the Siemens Power Corporation, the Shearon Harris fuel vendor.
The staff's evaluation of the licensee's proposed changes follows.
- 2. 0 EVALUATION The reason for the request is the severe power reduction specified by the current TS 3/4.2.3, RCS Flow Rate and Nuclear Enthalpy Rise Hot Channel
- Factor, which 'requires an initial power reduction to less than 50 percent
- and, subsequently, to less than 5 percent if measured flow is less than the specified limit.
The measured RCS total flow must be equal to or greater than 293,540 gpm x (1.0+Cj) where C
is a nominal flow measurement allowance.
The current value of C
1s 0.022,
- thus, the margin from the last measured value of 304,554 gpm is 1.53 percent.
During the recent refueling outage, the licensee implemented several significant changes that can affect measured RCS flow; the changes included elimination of the resistance temperature detectors, transition to a new nuclear fuel, and reduction in RCS average temperature T,.
None of these changes would significantly alter the actual RCS flow,
.but because of the small margin between flow and the TS limit there is the potential for a lower calculated flow that does not satisfy the value estimated by the above.formula.
Therefore, the proposed TS change is to preclude major power reduction due to minor changes to the measured flow.
Power operation with reduced flow requires a corresponding reduction in power and lowering of the power range neutron flux high trip setpoint.
Analyses performed by the Siemens Power Corporation indicates that the 1.5 percent power to 1.0 percent flow ratio along with the same reduction of the power 9408080040 940727 PDR ADOCK 05000400 P
4 I
range neutron flux high trip setpoint, ensures that the minimum departure from nucleate boiling ratio (MDNBR) margin is maintained for those events which utilize the power range neutron flux high trip setpoint function.
This power/flow reduction also maintains the enthalpy rise hot channel factor (F~)
at a value which is less than or equal to the value at 100 percent rated thermal power including measurement uncertainty.
For transients that depend on over-temperature delta temperature (OTBT), the staff has determined that the proposed power/flow reduction is acceptable.
In the OTET equation, hT is measured and QTo is the indicated hT at the rated thermal power and minimum required flow, thus,'hT/hTo is equivalent to a power fraction with respect to rated power.
Therefore, hT is a direct measure of reactor
- power, and when the minimum required flow is reduced by a small fraction, the hT will increase and, correspondingly, the estimated rated thermal power will increase by the same small fraction (while in reality power has not changed).
If power was then reduced by a correspondingly small
- amount, the hT/hT, would remain unchanged.
Therefore, by reducing the rated power and correspondingly reducing flow, the same OTGT setpoint will maintain the MDNBR margin.for those transients that rely on the OTBT trip.
In summary, the staff finds that the proposed TS changes that specify reduction of 1.5 percent of rated thermal power for every 1.0 percent of estimated flow below the minimum required flow for the rated thermal power will maintain the MDNBR and F~ margins for events which rely on power range neutron flux high power trip or an OTBT trip.
Therefore, the proposed changes are acceptable.
3.0 STAT CONSULTATION In accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendment.
The State official had no comments.
- 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 the Surveillance Requirements.'he 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
proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (59 FR 27079).
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 connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed
- above, that:
(I) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, 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:
L. Lois Date:
July 27, 1994
1 44
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AMENDMENT NO.
50 TO FACILITY OPERATING LICENSE NO. NPF-63 HARRIS, UNIT 1 DISTRIBUTION:
Docket File NRC/Local PDRs PD II-1 Reading File S. Varga D. Matthews P. Anderson N.
Le OGC D. Hagan G. Hill (2)
L. Lois T. Collins ACRS (10)
OPA OC/LFDCB J. Johnson, Acting, R-II cc:
Harris Service List
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