ML20213E456

Requests Concurrence W/Interpretation of Requirements for Compliance W/Gdc 2 & 4 Protection of safety-related Structures,Sys & Components from Internal Flooding & Internal Missiles.Interpretation Challenged by Utils

ML20213E456
Person / Time
Site:	Limerick, Rancho Seco, 05000000
Issue date:	07/14/1983
From:	Parr O Office of Nuclear Reactor Regulation
To:	Mattson R Office of Nuclear Reactor Regulation
Shared Package
ML20213E458	List: IA-87-244, Requests Concurrence W/Interpretation of Requirements for Compliance W/Gdc 2 & 4 Protection of safety-related Structures,Sys & Components from Internal Flooding & Internal Missiles.Interpretation Challenged by Utils ML20213E456 ML20214A872
References
FOIA-87-244 TAC-52656, NUDOCS 8307200562
Download: ML20213E456 (2)

Text

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Jgg, g 4 l MEMORANDUM FOR: Roger J. Mattson, Director Division of Systems Integration NRR THRU: g L. S. Rubenstein, Assistant Director for Core and Plant fy Systems Division of Systems Integration NRR I

FROM: Olan D. Parr, Chief. Auxiliary Systems Branch, Division of Systems Integration, NRR

SUBJECT:

ASB INTERPRETATION OF REQUIREMENTS FOR COMFLIANCE WITH GDC 2 AND 4 WITH RESPECT TO PROTECTION OF SPECIFIC STRUCTURES, SYSTEMS AND COMPONENTS FROM INTERNAL FLOC 014G OR INTERHAL MISSILES The purpose of this memorandum is to request your concurrencit with the Auxiliary Systems Branch's interpretation of the requirements for compliance with GDC 2 and 4 regarding protectio.1 of safety-related structures, systems and components from internal flooding and internal missiles. This matter is being brought to your attention at this time due to the fact that our interpretation as discussed below has been challenged by the Philadelphia Electric Company during the licensing review of the Limerick Generating St1 tion and by the Sacramento Municipal Utility District during the Appeal Board consideration of the restart '

. of Rancho Seco following the accident at TMI.

During the Limerick review, the applicant has questioned ASB's interpretation of compliance with GDC 2 and 4 regarding internal flooding follcwing an SSE ,

wherein the guidelines of Regulatory Guide 1.29, Positions C.) and C.2, are applied. Position C.1 applies directly to those structures, systems and com-ponents which are required to maintain the primary pressure boundary, safely shut the plant down or mitigate the consequences of an accident (the SSE), and thus identified those which are " safety-related " to be classified " seismic Category !" and are therefore to be protected from internal flooding. Position C.2 states that nonseismic Category I structures, systems or components whose failure could reduce the functioning of safety-related, seismic Category I structures, systems or components should be designed and constructed so that the SSE would not cause such failure. In ASB's evaluations we assume that the '

direct consequences of the initiating event are taken concurrent with that.

event and then compounded by a single active failure. When considering internal

! flooding following the SSE, we assume failure (total rupture) of one nonseismic Category I pipe in each compartment individually (the most limiting with respect to fluid loss) as a consequence of the event (SSE) and then take a concurrent single active failure (the most limiting from the standpoint of plant shutdowns.

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2 JUI.141983 Based on the above, we interpret compliance with Regulatory Guide 1.29 and therefore GDC 2 and 4 regarding internal flooding to consist of the following when nonseismic Category I fluid piping is in areas which may cause adverse flooding ofisafety-related equipment:

1. Only seismic Category I structures, systems and components may be assumed available to mitigate the consequences of flooding due to a nonseismic Category I pipe break;

2. If operator action is regt. ired, safety-related (seismic Category I) indica-tion and alams must be available to provide indication of flooding in safety-related areas;

3. Operator response time of 20 miautes from the control room and 30 minutes from outside the control room are assumed for detemining the resulting water level in affected compartments prior to mitigation of the concern.

For the Rancho Seco case, the staff was requested by the Appeal Board to review the capability of the. AFWS to comply with the current revision of the Standard Review Plan. Here the licensee has questioned ASB's interpretation of com-pliance with GDC 4 regarding internal missiles that could result from in-plant component overspeed failures and high-pressure system ruptures. Where safetyd related systems or components are located in areas containing nonsafety-related systems or components, the nonsafety-related systems or components are reviewed C, with respect to internal missile effects if the failure could preclude the intended safety function of the safety-related systems or components. In ASB's ^

evaluations, as is the case for the SSE, we assume that the direct consequences of the initiating events (missile impact damage) are taken concurrent with the event. That is, in a manner similar to Regulatory Guide 1.29, Position C.2, no missile generated from a nonsafety-related component should have the potential to damage a safety-related components. The event is then compounded by a single active failure. Consequently, for Rancho Seco, which has only two AFW trains, both trains must be protected.

While the Standard Review Plan (SRP) does not lead to easy interpretation the staff's implementation of the SRP as contained herein has been used for sometime.

We are not aware of any plants which have not been reviewed against these criteria during the last ten years. We therefore do not consider it necessary to treat these matters as part of the backfit procedure or to go before the CRGR.

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OlWD. Parr, Chief Auxiliary Systems Branch Division of Systems Integration cc: H. Denton E. Case D. Eisenhut T. Novak R. Purple ASB Members G. Lainas r /

Approved L CD Roger D. Mptson (