ML20209A862

Requests Addl Info Re Acceptability of Containment Isolation Provisions for RHR & Reactor Containment Fan Cooler Return Lines.If Provisions Meet GDC 57,approval to Lock Open Valves on Fluid Lines for Fire Protection Unnecessary

ML20209A862
Person / Time
Site:	South Texas
Issue date:	04/07/1987
From:	Kadambi N Office of Nuclear Reactor Regulation
To:	Goldberg J HOUSTON LIGHTING & POWER CO.
References
NUDOCS 8704280298
Download: ML20209A862 (2)

Text

' ~

, . o /

Docket Nos. 50-498 Dist'ribution and 50-499 C Docket file y ACRS(10)

Mr. J. H. Goldberg NRC/ Local'PDR' MRushbrook Group Vice President, Nuclear PAD #5 Reading RPerch Houston Lighting & Power TNovak PKadambi P.O. Box 1700 OGC-Beth EJordan Houston, Texas 77001 BGrimes JPartlow Gray File 3.6a NThompson

SUBJECT:

ACCEPTABILITY OF CONTAINMENT ISOLATION PROVISIONS FOR RHR AND RCFC RETURN LINES - REQUEST FOR ADDITIONAL INFORMATION ON THE SOUTH TEXAS PROJECT (STP).

During review of the fire protection measures at South Texas, your staff brought to NRC's attention a proposed engineering change notice for the South Texas Pro.iect plants that would entail locking open the inboard isolation valves on six fluid lines penetrating containment. Three of thE fluid lines are the RHR heat exchanger cooling water return lines and three are the reactor containment fan cooler (RCFC) return lines. The rationale for the proposed change is to support your philosophy of assuring the availability of redundant shutdown provisions for fire protection; an approach that goes beyond the regulatory requirements for fire protection. Since the staff only 4

requires demonstration of a single shutdown path, which has been satisfied, your proposal to alter the containment isolation system as indicated by the engineering change notice should be reconsidered.

Based upon a preliminary review, the NRC staff believes that the current containment isolation provisions for the subject fluid lines may not be acceptable. At issue is the applicable General Design Criterion. The staff has been told that STP claims that GDC 57 is the appropriate criterion. NRC disagrees with this assessment since the fluid system inside containment is not Safety Class 2, a design prerequisite for closed systems inside containment to serve as a containment isolation barrier. If GDC 57 was the applicable criterion, locking cpen the subject inboard valves in RHR and RCFC return Ifnes would be a moot regulatory issue since GDC 57 requires only one outboard isolation valve that may be automatic, remote manual or locked closed.

At this juncture, the staff requests additional information discussing the design pedigree of the component cooling water (CCW) system inside containment to justify acceptability as a containment isolation barrier. If a suitable basis exists for finding the CCW system design compatible with engineered safety 8704280298 870407 8 DR ADOCK 0500

o.. s.

-2 feature criteria, i.e. Safety Class 2 designation, the staff will accept the GDC 57 designation for the fluid lines and you need not seek approval to lock open the subject CCW systems valves.

If you have any further questions, please contact me at (301) 492-7272.

Sincerely, N. Prasad Kadambi, Project Manager Project Directorata No. 5 Division of PWR Licensing-A e}

PAD #5: PAD #5 VSNoonan h/7/87 / /87 i

4 1

I i

- _ _ . _ , . . , . _ _ _ _ _ _ . . _ . _ _ _ _ _ _ _ _ _ - . .- __ _ _ . . _ _ . _ _ - . _ _ _ , . . . . _ , .