ML20234A947

Safety Evaluation Re Util 870702 Submittal Re Containment Isolation for Various Instrument Lines.Util Proposed Alternate Basis to Meet GDC 55 to 10CFR50 App a Acceptable

ML20234A947
Person / Time
Site:	Grand Gulf
Issue date:	09/04/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20234A909	List: ML20234A905 ML20234A947
References
TAC-65707, NUDOCS 8709180205
Download: ML20234A947 (2)

Text

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uq c9 kg UNITED STATES

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D C. 20555

\ *** / ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONTAINMENT ISOLATION FOR VARIOUS INSTRUMENT LINES l GRAND GULF NUCLEAR STATION, UNIT 1 l DOCKET NO. 50-416

1.0 INTRODUCTION

In a submittal dated April 9,1982, the licensee comitted to comply with the guidelines of Regulatory Guide 1.11. " Instrument Lines Penetrating Primary Reactor Containment," and in particular, Regulatory Position C.1.c. This position indicates that the instrument lines which penetrate the primary reactor containment should be provided with an isolation valve capable of l automatic or remote operation from the control room or another appropriate location. Meeting the provisions of Regulatory Guide 1.11 is an acceptable alternate defined basis for instrument lines to meet the requirements of 10 CFR Part 50 Appendix A, General Design Criteria (GDC) 55 and 56, and discussed in -

Standard Review Plan (SRP) 6.2.4 The licensee, Systems Energy Resources, Inc.

(SERI), has identified six instrument lines which are within the scope of Regulatory Guide 1.11 and for which implementation of the affected provisions had been previously deferred.

Four of these instrument lines are for the pressure transmitters associated with the main steam isolation valve leakage control system (MSIV-LCS) and the other two lines are located between the outboard motor-operated injection valves and the inboard check valves of RHR-Loop C and the LPCS systems.

In a submittal dated May 30, 1986, the licensee had requested to withdraw its commitment to add the motor-operated valves to the affected instrument lines.

In order to support this request, SERI provided a dose consequences analysis.

The staff responded by transmitting a safety evaluation dated September 73, 1986. The staff found that the dose consequences are within acceptable limits and that the isolation valves need not be installed until the second refueling outage. However, the request for pennanent relief was denied because the licensee had not provided adequate assurance of the capability of the facility to maintain the containment leak-tight integrity without isolation valves in the instrument valves.

2.0 EVALUATION By letter dated July 2, 1987, SERI provided additional information in order to demonstrate containment leak-tight integrity is maintained without the additional motor-operated valves. By referencing SRP 6.2.4, " Containment Isolation System" and its purpose to fold-in all the relevant regulatory requirements, the licensee provided a detailed justification. The major elements that were listed are (1) since the affected instrument lines (six) are branch lines located between its two principal containment isolation valves, the inboard isolation valves are comon to the same penetration and thus provide one of the two required isolation barriers for each instrument line; and (2) the instrument line itself acts as the second isolation barrier since it is a closed system outside containment. To classify a line as a closed system, 8709180205 870904 PDR ADOCK 05000416 P pan

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nine criteria must be satisfied and are specified in ANSI /ANS-56.2-1984. This standard superseded a 1976 version which is recognized in Regulatory Guide 1.141 (April 1978). The latest ANSI standard is more complete, as it combines the elements of the earlier standard and SRP 6.2.4. The licensee is conducting an evaluation to determine if all the elements for a closed system outside containment are satisfied. In its submittal dated July 2, 1987, SERI identified the elements that are satisfied and several elements that require further evaluation. They have comitted to implement design changes if deficiencies are found. The staff concurs with SERI's justification, i.e.,

the motor-operated valves in the six affected instrument lines are not needed.

l It should be noted that the affected instrument lines are designed to withstand rated reactor pressure and temperature conditions. The four MSIV-LCS penetrations are exposed to the main steam line conditions during nonnal operation, whereas the predicted post-LOCA conditions are under more benign, e.g., a peak pressure o# about 12 psig, thereby demonstrating the inherent design capability as compared to the relative minor challenges of the LOCA situation. As for the other two penetrations, the normal operating conditions are more comparable to the LOCA environmental conditions. -

SERI has also indicated in its July 2, 1987 submittal that in the event one of the pressure transmitters attached to the instrument lines requires removal for maintenance, SERI proposes to add additional manual valves as appropriate during the next refueling outage to provide for improved maintenance capability.

The staff expects SERI to confirm that all relevant requirements are met.

3.0 CONCLUSION

Contingent upon the instrument lines meeting all the criteria specified for a closed system outside containment, SERI has demonstrated that these instrument lines maintain containment leak tight integrity without additional motor-operated isolation valves. Therefore, SERI has provided an acceptable alternate basis to meet the requirements of GDC 55 (10 CFR 50 Appendix A). The licensee should infonn the staff on its findings or deviations by the end of the next refueling outage (RF02) to support complete resolution on this subject.

Dated: Septemher 4, 1787 Principal Contributor:

A. Notafrancesco, Plant Systems Branch, DEST