ML20209E630
| ML20209E630 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/05/1985 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Butcher E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 85-094A, 85-94A, NUDOCS 8507120042 | |
| Download: ML20209E630 (5) | |
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ncernuknt thst Of]iceika36tES NuboQeOvns OrwpunesRaw11ca Rtzbnunu411ryrabs 23.%1 July 5, 1985 VIRGINIA POWER Mr. Harold R. Denton, Director Serial No. 85-094A 6ffice of Nuclear Reactor Regulation N0/DAS:acm Attn:
Mr. Edward J. Butcher, Acting Chief Docket Nos. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing License Nos. NPF-4 U. S. Nuclear Regulatory Commission NPF-7 Washington, D. C. 20555 Gentlemen:
VIRGINIA POWER NORTH ANNA POWER STATION, UNITS 1 AND 2 CONFORMANCE WITH REGULATORY GUIDE 1.97 Virginia Power letter, Serial No.84-094, dated May 10, 1985, provided a partial response to your letter of February 8, 1985, which requested additional information concerning conformance with Regulatory Guide 1.97.
The attachment to this letter provides responses for five of the remaining seven items. The remaining two items are undergoing additional review to insure technical correctness and to provide a clear, concise discussion of each item. Responses for both of these items will be provided by August 2, 1985.
Your letter of February 8, 1985, also requested that we provide comments if the NRC contractor's assessment of conformance included any incorrect assumptions or reflected a commitment beyond the intent of previous Virginia Power responses. We are reviewing both our response of January 31, 1984, and the NRC contractor's report to make that determination. The results of this validation process will be forwarded separately, if comment is required.
If you have any questions, or need additional information to complete your review of this partial response, please contact us.
Very truly yours, l
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W' V. L. Stewart Attachment 8507120042 850705 PDR ADOCK 05000338 p]
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Dr. J. Nelson Grace Regional Administrator Region II Mr. M. W. Branch hTC Resident Inspector North Anna Power Station
NORTH ANNA POWER STATION REGULATORY GUIDE 1.97 RESPONSE TO NRC LETTER DATED FEBRUARY 8, 1985 NRC letter, dated February 8,1985, on conformance with Regulatory Guide 1.97 identified sixteen open items and requested a Virginia Power response to each item. Responses to nine of these items, were provided in Virginia Power letter Serial 85-094 dated May 10, 1985. Five of the remaining seven items are addressed below.
Item 4 RHR system flow -- environmental qualification should be addressed in accordance with 10 CR 50.49 (Section 3.3.4).
Virginia Power Response The Residual Heat Removal (RHR) System at North Anna does not serve as an Engineered Safety Feature.
Unlike those of most other Westinghouse
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plants, the North Anna RHR and Low Head Safety Injection systems are separate and independent. The RHR is not a safety grade system and is not required to bring the plant to a design base safe shutdown condition. As
_ stated in UFSAR Section 5.5.4.3.3, "The system is not required to operate in the post-accident containment atmosphere."
Since the RHR system is not designed to remain operable during post-accident conditions, we believe that the variable of RHR flow should be reclassified as a Category 3 variable for North Anna and the present instrumentation accepted without modification.
Item 5 RHR heat exchanger outlet temperature environmental qualification should be addressed in accordance with 10CFR 50.49 (Section 3.3.4).
Virginia Power Response As discussed in Item 4 above, we believe this variable should be reclassified as a Category 3 variable consistent with the qualification of the RHR System as specified in UFSAR, Section 5.5.4.3.3.
The RHR System and accordingly the variable of RHR heat exchanger outlet temperature is not required post-accident.
Item 6 Accumulator level the licensee should show, by analysis, that the existing range will adequately cover the expected post-accident levels or provide instrumentation with a range as recommended by the regulatory guide; environmental qualification should be addressed in accordance with 10 CFR 50.49 (Section 3.3.5).
I
o Virginia Power Response The present accumulator level indication is adequate for its design function of confirming that accumulator contents are available for discharge during an accident.
During power operation the accumulator isolation valve is open, power to the valve is removed, and during start-up the breaker is verified locked open in accordance with the Technical Specification. With the isolation valve open and the breaker locked open, two check valves in series in the accumulator discharge line prevent the tank from being discharged until RCS pressure is less than the accumulator pressure.
In this arrangement the operator has no direct control over accumulator tank level in accident conditions. During rapid RCS depressurization, the level in the accumulator decreases based on the differential pressure between the RCS and the accumulators. Complete discharge of the accumulator is therefore determined by the primary system pressure.
Furthermore, no subsequent post-accident actions are taken based on accumulator level.
Based on a range consistent with Technical Specifications and accumulator design function, no discharge control function, and no identified post-accident operator use in Emergency Operating Procedures, we believe the existing instrumentation to be adequate and that accumulator tank level should be reclassified as Category 3 instrumention for North Anna.
Item 7 Accumulator pressure -- environmental qualification should be addressed in accordance with 10 CFR 50.49 (Section 3.3.5).
Virginia Power Response Upon reevaluation of the variable of accumulator pressure with respect to the Emergency Operating Procedures, we have determined that the operator should monitor and may take contingency actions based on this variable.
Accordingly, we commit to upgrade this variable to include environmental qualification during the refueling outages presently scheduled to occur in 1987.
Item 8 Accumulator isolation valve position-environmental qualification should be addt assed in accordance with 10 CFR 50.49 (Section 3.3.5).
Virginia Power Response Consistent with the response in Item 6 above, the present accumulator isolation valve position indication is adequate for its design function of confirming that accumulator contents are available for discharge prior to an accident. During power operation the accumulator isolation valve is open, power to the valve is removed, and during start-up the breaker is verified locked open in accordance with the Technical Specifications.
With the isolation valve open and the breaker locked open, two check valves in series in the accumulator discharge line prevent the tank from i
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1 being discharged until RCS pressure is less than the accumulator pressure.
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During rapid RCS depressurization, the level in the accumulator decreases I
based on the differential pressure between the RCS and the accumulators.
Complete discharge of the accumulator is therefore determined by the primary system pressure.
Based on' accumulator design function and no discharge control function, we believe the existing instrumentation to be adequate and that accumulator isolation valve position indication should be reclassified as Category 3 instrumentation for North Anna.
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