ML20106B652
| ML20106B652 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/31/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20106B650 | List: |
| References | |
| NUDOCS 8502120004 | |
| Download: ML20106B652 (3) | |
Text
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UNITED STATES g
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g NUCLEAR REGULATORY COMMISSION g - '.
f WASHINGTON D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION j
RELATED TO AMENDMENT NO. 37 TO FACILITY OPERATING LICENSE NPF-12 SOUTH CAROLINA' ELECTRIC & GAS COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY l
I.
INTRODUCTION By letter dated June'19, 1984 (Reference 1), South Carolina Electric and Gas Company (SCE&G) requested an amendment to the V. C. Summer Technical Specifications. The amendment would change the reactor coolant system flow measurement uncertainty from 3.5% to 2% in Technical Specification 3.2.3, "RCS Flow Rate and Nuclear Enthalpy Rise Hot Channel Factor" and in its basas.
The amendment would also add a third region (Region III) of acceptable operation' to Technical Specification Figure 3.2.3 "RCS Flow Rate versus R."
This reaion would allow plant operation with a 2% reduction in power for avery 1% reduction in flow from 100% to 95% total flow.
By letter dated November 29,1984 (Ref. 2), SCE&G requested that their initial submittal be revised to eliminate the request for a reduced measure-ment uncertainty of 2% and then revise the Region III of acceptable operation to reflect a 3.5% reactor coolant system (RCS) flow measurement uncertainty instead of the 2% measurement uncertainty.
l The initial amendment request was noticed in the Federal Register (49 FR 42830) on October 24, 1984. The revised amendment request effec-tively only eliminated the request for a revised RCS flow measurement uncertainty, which necessitated changing some Region III values. Because these changes were small and the basic amendment request, as noticed, of l
reducing power by.2% for every 1% reduction in flow from 100% to 95% total i
flow was not changed, this amendment request was not renoticed.
l l
II.
EVALUATION l
The licensee presented information (Ref. 2) to justify operation at up to t
10% reduced Rated Thermal Power (RTP) if measured RCS flow is found to be less than the Thermal Design (TD) flow. This is inste'ad of the requirement of the current Technical Specification 3.2.3, Figure 3.2-3 which limits operation to less than 5% of RTP if the measured RCS flow is less than the TD flow used in the plant safety analyses. The licensee. presented infoma-tion on relationships between core power, flow and depar'"re from nucleate boiling (DNB) which resulted in a relationship between powtr and flow of 0.555. However, instead they proposed a conservative value of 2.0.
For l
comparison, a staff independent calculation was made using sensitivity fac-tors from a Battelle Pacific Northwest Laboratories Study (Reference 3).
I The value obtained was 0.833 instead of 0.555. However, the licensee's pro-posed value of 2.0 for the power to flow relationship remains conservative to 8502120004 850131 DRADOCH05000g
1 l
either calculation.
Based on this value of 2.0, the licensee requested
- that a new region of acceptable operation be added to Figure 3.2-3 in the Technical Specifications for:
- 95% TD flow 5 RCS flows 100% TD flow.
4 The licensee has modified Figure 3.2-3 such that the maximum power level for the new region is reduced.by 2% for each 1% reduction in measured flow i
below TD flow in steps of 2% power up to a maximum of 10% reduction in
' rated power at 95% TD flow The Technical Specification accident analysis
- results have been evaluated by the licensee to determine the-impact of operating within the defined new region (Region III) of Figure 3.2-3 with the imposed restriction.
It was found that sufficient margin exists in 4
l all cases to allow continued plant operation; no Technical Specification limits require modifications, including core limits, overtemperature delta l
T, overpower delta T, and Power Range Neutron Flux High Setpoints. This analysis took-account of the increased margin to DNB because of power reduction. The licensee will restrict the power level to 100% Rated Thermal Power (RTP) for Figure 2.1-1, " Reactor Core Safety Limit - Three Loops in Operation" when operating in the defined new region (Region III) of Figure i
3.2-3 at the 95% to 100% reduced TD flow conditions. The staff has found l
these, changes to be acceptable.
In conclusion, we have reviewed the analysis performed by the licensee to justify the proposed Technical Specification changes for operation of the V. C. Summer plant at the proposed 2 to 1 power / flow tradeoff for operation l
betweem 95% TD to 100% TD flow.- The review included sensitivity studies j
on the impact of flow reduction on DNB thermal margin and DNB ratio limit-ing transients.
The sensitivity analysis was found to be acceptable. We have found that the proposed Technical Specification changes properly account for the power / flow tradeoff and are, therefore, acceptable.
III. ENVIRONMENTAL CONSIDERATION This amendment involves a change in the use of a facility component located within the restricted area as defined ~ in 10 CFR fart 20. The 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 this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Sec 51.22 (c)(9).
Pursuant to 10 CFR 51.??(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of'this amendment.
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IV. CONCLUSION i
i The Commission made a proposed determination that the amendment involves-no significant hazards consideration which was published,in the Federal Register (49 FR 42830).on October 24, 1984, and consulted with the state i
of South Caro' lina.
No public domments were received, and the state of i
South Carolina did not have any comments.
?
We have concluded, based on-the considerations discusse'd'above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the prnoosed manner; and (2) such l
activities will be conducted in compliance with the Commission's regula-tions 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.
REFERENCES 1.
Letter from 0. W. Dixon, Jr., South Carolina Electric and Gas Company, to H. R. Denton, (NRC), dated June 19, 1984.
2.
Letter from 0. W. Dixon, Jr., South Carolina Electric'and Gas Company, to H. R. Denton. (NRC), dated November 29, 1984.
3'.
G. M. Hesson and J. M. Cuta, " Analysis of the Sensitivity of Calculated MDNBR to Eight Selected DNB Parameters" FATE-70-101, Battelle Pacific Northwest Laboratories, March 1979.
Principal Contributor: Jon B. Hopkins, Licensing Branch No. 4, DL Harry Balukjian, Core Performance Branch, DSI 4
Dated:
January-31, 1985 9
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Janu;ry 31, 1985 AMENDMENT N0.37 TO FACILITY OPERATING LICENSE NO. NPF Virgil C. Summer Unit 1 DISTRIBUTION w/ enclosures:
bec w/ enclosures:
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Docket No. 50-395 NRC PDR LB #4 r/f
. Local PDR J. Hopkins NSIC H. Duncan PRC System OELD
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E. Adensam R. Diggs, ADM T.Barnhart(4)
J. N. Grace, DPR:I&E E. L. Jordan, DE0A:I&E L. Harmon, ISE D. Brinkman, SSPB H. Balukjian, CPB 6
i, N. '. 21.'.
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