ML20043A656
| ML20043A656 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/17/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20043A654 | List: |
| References | |
| NUDOCS 9005220365 | |
| Download: ML20043A656 (3) | |
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UNITED STATES
' NUCLEAR REGULATORY COMMISSION
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION j
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' SUPPORTING AMENDMENT NO. 92 TO FACILITY OPERATING LICENSE NO. NPF-12 SOUTH CAROLINA ELECTRIC & GAS COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY
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-VIRGIL C. SUMMER NUCLEAR STATION, UNIT NO. 1
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DOCKET NO. 50-395
1.0 INTRODUCTION
By-letter dated November 20, 1989, South Carolina Electric & Gas Company 1
(the licensee) proposed a change to the Surveillance Requirement fer the L
fullclosuretimeforthemainsteamlineisolationvalves(MSIV)for V.C.SummerNuclearStation(Summer). Surveillance Requirement 4.7.1.5, Main Steam Line Isolation Valves, requires that the each MSIY be
@ monstrated 0PERABLE by verifying full closure within five seconds. The f
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licensee is proposing to change the Surveillance Requirement to demonstrate i
i full closure within seven seconds.
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2.0 BACKGROUND
Surveillance Requirement 4.0.5 addresses the inservice testing (IST)
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program for ASME Code Class 1, 2, and 3 components. The MSIV is one of 1
those components and a stroke time test is one of.the applicable tests.
The MSIV are required to be operable to ensure that no more than one steam generator will blowdown in the event of a steam line rupture.
'l The closure time of the Surveillance Requirement-is required to stay consistent with the assumptions made by the licensee in the accident analysis presented in the Summer Final Safety Analysis Report (FSAR).
j The MSIV were designed with a specified closure time of five seconds.
q The TS limit'is also the same as the design, five seconds. The change to a-sevet second limit on stroke time would remain within the bounds of the i
actuation times assumed in the accident analyses. The actuation times assumed in the accident analyses were ten seconds for both the main steam isolation on reactor building pressure, high-2 and main steam isolation on steam line pressure. low. No credit was taken for closure of the MSIV in the accident analysis for high steam line flow coincident with Low-Low-T,yg.
j Because the TS time limit and the design closure times are the same, there is no allowance for stroke time degradation. Thus, a meaningful trend of valve performance for the IST program cannot be established to allow problem analysis or to pre-plan corrective maintenance. The change to i
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.o seven seconds would allow trending, permit planning and analysis and would decrease challenges to safety-related equipment and reduce the inherent exposures resulting from maintenance necessary to bring the valve closure time back to five seconds.
3.0t EVALUATION The engineered safety feature actuation system (ESFAS) response times are used to assure actuation times are maintained within accident analyses.
The most limiting ESFAS response time is nine seconds. The licensee's proposed change will not alter the ESFAS response time limits. Therefore, the assumptions in the accident analyses will not be affected by the change.
The proposed change to the surveillance requirement affects a surveillance-requirement which is performed as part of the IST program. The proposed change does not alter the requirements for identifying corrective actions or declaring the MSIV inoperable. Approval of the proposed TS change may actually enhance the IST program since the change would allow the license to trend the degradation of the MSIV. The TS change could also result in a decrease in the potential for cycling the plant through a cooldown and subsequent heatup as a result of declaring MSIV inoperable due to closure times that are within the accident analyses. Thus, challenges to safety-related equipment would be reduced and in-plant exposures, as a result of maintaining the five second closure time, would also be reduced.
A review of the Section 10.3.2.3 of the Sunner FSAR indicates that the MSIV have a closure time of 5 seconds upon receipt of the signal.
In addition,- a review of the steamline break analyses'in Chapter 15 of-the-FSAR also indicates that the total elapsed time for the MSIV to close is 10 seconds in one case and 12 seconds in another. Based upon the above information, it is clear that the stroke time results are within the design basis of the facility as presented in the FSAR.
The staff finds the proposed change in MSIV full closure time to be acceptable.
5.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the Surveillance Requirement. 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 off site and that there is no significant increase in individual or cumulative occupational radiation exposure. The Connission has previously issued a proposed finding that this amendment involves no l
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significant hazards-consideration and there has been no public coment on such finding. Accordingly, this amendment meets the eligibilit criteria
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for categorical exclusion set forth in 10 CFR Section 51.22(c)(y).
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.
6.0 CONCLUSION
The Comission has issued a " Notice of Consideration of Issuance of Amendment to Facility Operating License and Propose No Significant Hazards Consideration Determination and Opportunity for Hearing" which was published in the Federal Register on January 10, 1990 (55'FR 940) and consulted with the. State of South Carolina. No public coments or request for hearing-were received, and the State of South Carolina did not have coments.
l The staff has concluded, based upon the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the p(ublic will not be endangered by operation in the proposed manner,2) such activitie regulations, and (3) the issuance of this amendment will not be inimical to the comon defense and security or to the health and safety of the public.
i Principal. Contributor:
J. Hayes Datedi May 17, 1990 a