ML20072D302
| ML20072D302 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 03/15/1983 |
| From: | James Smith LONG ISLAND LIGHTING CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| SNRC-841, NUDOCS 8303210173 | |
| Download: ML20072D302 (3) | |
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LONG ISLAND LIGHTING COM PANY a
SHOREHAM NUCLEAR POWER STATION 1
P.O. BOX 610, NORTH COUNTRY ROAD + WADING RIVER, N.Y.11792 Direct Dial Number March 15, 1983 SNRC-841 Mr. Ilarold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 NRC Request for Information Regarding Feedwater Pipe Breaks Outside Containment Shoreham Nuclear Power Station - Unit 1 Docket No. 50-322
Reference:
Letter NRC (Mr. A. Schwencer) to LILCO (Mr. M.
S.
Pollock) dated January 6, 1983
Dear Mr. Denton:
The referenced letter made the following two requests for information regarding feedwater pipe breaks outside containment:
(1)
" Provide the basis for assuring that the feedwater isolation check valves can perform their intended function and satisfy GDC 54 and 55 following a feedwater line break outside containment."
(2)
" Discuss what actions have been taken to preclude the possibility of a feedwater pump trip transient causing a feedwater line break outside containment."
The issue addressed in item (1) has been evaluated for the Shoreham Nuclear Power Station with satisfactory conclusions.
Actions have also been taken in the Shoreham plant design with regard to item (2).
Both items are discussed in detail below.
The feedwater system piping outside containment originates in the turbine building at the feedwater pumps and enters the steam tunnel after passing through the turbine building interface wall.
The two 18" diameter lines then travel in parallel up the steam tunnel, through the reactor building wall (jet impingement barrier / rupture restraint), and then to the primary containment penetrations.
Containment isolation for each line is achieved by means of a simple check valve inside containment and a positive closing testable check valve outside containment.
In addition, each feedwater line also has a leaktight motor operated stop check valve just upstream of the outside containment isolation valve.
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y SNRC-841~
~ March 15,-19B3 Page 2
'A feedwater. pipe break outside of containment would result in a rapid pressureftransient in the line with flow reversal calculated to1begin'soon after-a postulated instantaneous guillotine break.
~
'The check valves will begin to close in response to the flow reversal; the disks will accelerate as the velocity of reversed feedwater flow increases.
The check valves will close suddenly o
.after. flow.~ reversal begins and.a large pressure differential is calculated'to result.
During the time of-valve closure, the isolation check valves will be stressed both due to the impact of the disk on the seat and due to the surge pressure acting on it.
The Shoreham feedwater check valve disks are 16.5" in diameter and vary uniformly in thickness from 2.25" at the outer radius to 3.375" at the center.
An analysis; ofi these. valves for this postulated dynamic event indicates that local _ yielding of the disk material ~would occur but that a significant margin would remain with respect to ultimate strain limits and that structural integrity of the valve would be retained.
Item (2) of the request refers to the feedwater pump trip transient.
This event is identified as a design condition for the feedwater system in the Shoreham design specification for ASME piping.
The effects of this event have been considered in the design of both the ASME and non-ASME portions of the feedwater system.
(Feedwater piping outboard of the leaktight MOV is ANSI B31.1)
Therefore, the possibility of a feedwater pipe break due to a feedwater pump trip transient has been adequately considered in the system design.
In summary, the Shoreham feedwater piping outside containment has been designed for all appropriate loading conditions, including a feedwater pump trip transient, thereby minimizing the possibility of a stress induced pipe break.
In addition, the effects on the feedwater isolation check valves of a low probability postulated non-mechanistic pipe break event have been evaluated and found to be acceptable.
A significant additional degree of safety is also provided by the presence of the leaktight motor operated stop check valves located just upstream of the outside containment isolation valves.
On this basis, the criteria of GDC 54 and 55 applicable to the feedwater isolation check valves following a feedwater pipe break outside containment are satisfied.
Very truly yours, h
?
L. Smith Manager, Special Projects Shoreham Nuclear Power Station JLS/ laws 3 cc:
J.
Higgins - NRC Site Inspector "All Parties Listed in Attachment 1"
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i ATTACHMENT 1 m
. Lawrence ~Brenner, Esq.
-Herbert H.-Brown, Esq.
' Administrative ~ Judge Lawrence Coe Lanpher, Esq.
Atomic-Safety and' Licensing Karla J. Letsche, Esq.
' Board Panel, Kirkpatrick, Lockhart, Hill-U.S. ' Nuclear: Regulatory Commission Christopher & Phillips
, Washington, D.C.
20555-8th. Floor 1900 M Street, N.W.
Washington, D.C.-
20036 Dr.L Peter A.-= Morris Administrative ~ Judge
-Atomic Safety and-Licensing Mr. Marc W.
Goldsmith Board Panel Energy Research Group U.S.: Nuclear. Regulatory Commission 4001 Totten Pond Road Washington, D.C.
20555 Waltham, Massachusetts 02154 Dr. James H. Carpenter MHB Technical Associates Administrative Judge 1723 Hamilton Avenue Atomic' Safety.and Licensing Suite K Board Panel San Jose, California 95125
-U.S.
Nuclear Regulatory Commission Washington, D.C.
20555 Stephen B.
Latham, Esq.
Twomey, Latham & Shea Daniel F. Brown, Esq.-
33 West Second Street Attorney P.O. Box 398 l Atomic Safety and Licensing
-Riverhead, New York 11901 Board Panel U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Ralph Shapiro, Esq.
Cammer and Shapiro, P.C.
9 East 40th Street Bernard M.-Bordenick, Esq.
New York, New York 10016 David A.
Repka, Esq.
U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Matthew J.
Kell'y, Esq.
State of New York James Dougherty Department of Public Service
'3045 Porter Street Three Empire State Plaza Washington, D.C.
20008 Albany,-New York 12223
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