ML20206G633
| ML20206G633 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/30/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206G606 | List: |
| References | |
| NUDOCS 8704150068 | |
| Download: ML20206G633 (4) | |
Text
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8 NUCLEAR REGULATORY COMMISSION n
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SAFETY EVALUATION BY THE OFFICE OF NifCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-12 SOUTH CAROLINA ELECTRIC & GAS COMPANY SOUTH CAROLINA PURLIC SERVICE AUTHORITY i
VIRGIL C. SUMMER NUCLEAR STATION UNIT NO. 1 i
DOCKET NO. 50-395 INTRODUCTION l
By letter dated June 27,1986 (Ref. II, South Carolina Electric and Gas Com-pany (the licensee) requested changes in the Technical Specifications (TS) for V. C. Sumer Nuclear Station to reflect the results of an RCS flow measurement uncertainty analysis. The analysis provided the basis for reducing the flow measurement uncertainty from 3.5% to 2.1%. By letters dated November 21, 1986 (Ref. 5) and February 25, 1987 (Ref. 6), the licensee supplemented the 4
application by providing a clarification and a FSAR revision concerning the inspection of feedwater flow venturi nozzles.
These supplemental letters did not change the action described in the Federal Register Notice or the initial no significant hazards consideration determination. Therefore, the application was not renoticed.
j EVALUATION The licensee provided an analysis for the RCS flow measurement uncertainty to support the requested value of 2.1%. This analysis used a statistical method similar to that in Ref. 2 which has been applied to other plants using the Westinghouse PWR design. The results indicated that the total precision calorimetric RCS flow uncertainty was 11.790%. To establish the overall uncer-tainty, the effect of using three normalized elbow taps (1 per loop calibrated against the precision calorimetrici was included. This additional uncertainty for the elbow taps amounted to *0.910% when using a process computer display and a slightly smaller value of 10.898% when using a Digital Volt Meter (DVMI reading. By combining the elbow tap uncertainty with the precision calorimetric uncertainty, using the square root of the sum of squares method, the total RCS uncertainty in the analysis resulted in values of +2.008% and
+2.003% respectively for the process computer display and DVM readings. This uncertainty value of approximately +2.00% was rounded up by the licensee by
+0.1% to 2.1%.
Nomalization of the elbow taps with the precision heat balance at each refuel-ing is required to take advantage of the results of the measurement unce'rtainty' analysis supporting the 2.1% value. A statement regarding this recuiremm t was provided by the licensee for insertion in the FSAR'(Ref. 5).
In discussions 8704150068 870330 DR ADOCK 0500 5
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with the licensee, it was learned that each feedwater flow venturi meter is to be inspected before each refueling and is to be cleaned by a hydrolasing pro-cess which makes use of a high pressure, high temperature steam / water mixture.
The licensee has stated (Ref. 6) that the FSAR will include a requi.rement for the inspection and hydrolasing of the venturi meters at each refueling outage.
Because the licensee has committed to inspect and clean the venturi meters at each refueling outage, the 0.1% additional amount of uncertainty for venturi fouling is not applied in the analysis. We have reviewed the analysis and have i
found the 2.1% RCS flow uncertainty value to be used in TS 3/4.2.3 to be acceptable.
The TS change also modifies Figure 3.2-3, "RCS Total Flow Rate Ys R-Three Loop Operation," to reflect the 2.1% RCS flow uncertainty value.
Previously (Ref. 3),
the licensee had submitted an analysis to support a request to modify this figure to define allowable power levels for an RCS flow rate less than 100% of thermal design flow (TDF) with corrections for flow measurement uncertainty. A 2 to 1 power / flow tradeoff for RCS flow deficits of up to 5% was approved in Amendment No. 37 (Ref. 4). The maximum power level was to be reduced by 2% for each 1% reduction in flow in the range from 100% to 95% total flow.
Figure 3.2-3 was modified to show the allowable RCS flow for reduced Rated Thermal Power (RTP) up to 10% lin the range from 100% to 90% RTP) in increments of 2% RTP.
However, with the present request (Ref.1) for reduction of RCS flow measurement uncertainty from 3.5% to 2.1%, the previous TS values for RCS flow for this figure are altered and need to be changed. These changes are included.
It is noted that the TDF was reduced from 98,000 gpm per loop to 96,200 gpm (288,600 gpm for 3 loops) in Amendment No. 45 to the TS when the Westinghouse BART Evaluation Model was adopted. We have examined the proposed changes in Figure 3.2-3 and have found the changes to be in agreement with the effect of the new measurement uncertainty value of 2.1%. The changes are, therefore, acceptable.
j TS CHANGES The changes to the TS for V. C. Summer as a result of changing the RCS flow measurement uncertainty from 3.5% to 2.1% involve Section 3/4.2.3. These changes are discussed below:
(11 Section 3/4.2.3 - (Page 3/4 2-8)
A sentence stating that
" Figure 3.2-3 includes measurement uncertainties of 3.5% for flow" was changed to replace the 3.5% value with 2.1%. This change is acceptable for reasons explained in the evaluation.
(2) Fioure 3.2 RCS Total Flow Rate vs. R-Three Loop Operation -
(Page 3/4 2-10)
I This figure has five incremental changes in RTP from 100% down to 90% with corresponding reduction in values for RCS total flowrate in gpm down to 95%. Because of the change in RCS flow measurement uncertainty from 3.5%
to 2.1%, the values shown in Figure 3.2-3 needed to be adjusted. We found these changes to be acceptable as explained in the evaluation.
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. (3) Bases for Section 3/4.9.3 - (Page B 3/4 2-5) i The statement in this bases
" Measurement errors of 3.5% for RCS total flow rate...." was revised to change the 3.5% to 2.1%Mhis agrees with the proposed change and is, therefore, acceptable.
It is noted that there is no statement in the bases about the usual 0.1% penalty for venturi foul-ing. This has not been applied as the venturi meters are to be inspected and cleaned at each refueling. Nomalization of the elbow taps with the precision heat balance at each refueling is required. The licensee has confimed (Ref. 5 and 6) that the elbow taps will be nomalized with the precision heat balance and the venturi meters will be inspected and j
cleaned at each refueling outage.
6 S M ARY We have reviewed the RCS flow measurement analysis performed by the licensee to l
Justify the proposed TS changes for the V. C. Summer. Nuclear Station. The RCS flow measurement analysis resulting in a measurement uncertainty of 2.1% in place of 3.5% was found to be acceptable. This change of measurement uncertainty 1
was found to be correctly implemented in the required modifications to Figure l
3.2-3 to show the 2 to 1 power / flow tradeoff. Changes were also required on pages 3/4 2-8 and B 3/4.2.3 to reflect the new flow measurement uncertainty value of 2.1%. We find that the proposed TS changes are acceptable.
ENVIRONMENTAL CONSIDERATION This amendment involves a change in the use of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has detemined 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 expcsure. The Comission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public coment on such findina. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 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 this amendment.
i CONCLUSION We have concluded, based on the considerations discussed above, that:
(1) there is reasonable 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.
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i 4-References 1.
Letter from D. A. Nauman, South Carolina Electric and Gas Company, to H. R. Denton, NRC, dated June 27, 1986.
2.
Letter from E. P. Rahe, Westinghouse Electric Corporation to C. H. Berlinger, NRC, dated March 31, 1982.
3.
Letter from O. W. Dixon, Jr., South Carolina Electric and Gas Company, to H. R. Denton, NRC, dated June 19, 1984.
4.
Letter from E. Adensam, NRC, to 0.W. Dixon, Jr. South Carolina Electric and Gas Company, dated January 31, 1985.
5.
Letter from D. A. Nauman, South Carolina Electric and Gas Company, to H. R. Denton, NRC, dated November 21, 1986.
6.
Letter from D. A. Nauman, South Carolina Electric and Gas Company, to H. R. Denton, NRC, dated February 25, 1987.
Dated: March 30, 1987 Principal Contributors:
J. Hopkins, Project Directorate #2, DPLA
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H. Balukjian, Reactor Systems Branch, DPLA w,
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