ML20198J697
| ML20198J697 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/06/1998 |
| From: | Langenbach J GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 6710-97-2533, GL-97-04, GL-97-4, NUDOCS 9801140190 | |
| Download: ML20198J697 (5) | |
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GPU Nucleer,Inc.
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Route 441 South M de wn 1 057 0480 Te! 717.S44 7621 6710-97-2533 January 06, 1998 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Gentlemen:
Subject:
nree Mile Island Nuclear Generding Station (TMI 1)
Docket No. 50-289 ~
Facility Operating License No. DPR-50 Generic Letter 97-04 Response
References:
(1) USNRC Generic Letter 97-04," Assurance of SufTicient Net Positive Suction Head for Emergency Core Cooling and Containment 11 eat Removal Pumps", dated 10/7/97.
On October 7,1997, the Nuclear Regulatory Commission issued the referenced generic letter regarding a safety-significant issue which may have generic implications for degrading perfonnance of emergency core cooling system (including core spray and decay heat removal) and containment heat removal pumps. This generic letter requested addressees to provide, within 90 days, specific information for each of their facilities. Attaclunent I to this letter provides the requested information for TMI l.
If you have any questions or comments on this matter, please contact Ron Zak, Corporate Regulatory Affairs at (973) 316 7035.
Very truly yours, 00 %
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James W. Langenbath Vice President and Director, TMl jgod i
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I, James W.1.angenbach being duly sworn, state that I am a Vice President and Director of GPU Nuclear, Inc. and that I am duly authorized to ewcute and file this response on behalf of GPU Nuclear. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, tlu y are based upon information by ot!.er GPU Nuclear emplo)ws and/or consultants. Such information has been reviewed in accordance with company practices and I believe it to be rehable.
D'ldb' tlb James W. LangenbachU Vice President and Director TMl Signed and sworn before me this day s m - 199h.
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Notarial Se'll Burannn C Male A hotyy Pubhc r
Londord"ty T wp. D,wnhiri County i Gomm.,r.too lb F NOV i'E 19 X) f P
Me.nna hmosylvania A: m;d cc et Natanes c: Administrator, NRC Region i Senior Resident inspector, TMI-l TMI l NRC Project Manager
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O 6710-97-2533 Attact ment 1 Page1of3 AHAQMENT I TMI-l Rcjpolnse to.Qgngjiglgtter 97-04 1.
Specify the general methodology used to calculate the head loss associated with the ECCS suction strainers.
The available net positive suction head (APSHA) of the pumps is calculated using the following relationship:
NPSH.e = h. - h, + h - hs where:
- h. is the atmospheric pressure above the Reactor Building (RB) Sump liquid. When evaluating NPSH the value of this term is taken as ^he vapor pressure of the sump liquid.
h,is the saturation precsure of the RB Sump liquid. When evaluating NPSH the value of this term is taken at the maximum liquid temperature following the initiation of RB sump recirculation.
That temperature occurs at the time of recirculation.
g h, is the static fluid pressure associated with the pumps. It repres.nts the pressure associated with the weight of water above the centerline of the pump inlet. it is based on a conservative calculation of the RB water level.
. ha is the head loss associa'ed with the flow through the system. The head loss calculation is an evaluation of the piping length, geometry and fittings that include 2e sump screens. The friction factors, geometry and fitting loss coefficients am establided using standard engineering methods.
The TMI-l ECCS suction strainer consists of a large box in the reactor building sump, covered 'oy a mesh screen with 0.125 inch openings that prevent large particulate material from entering the pump suctions. The opening size is consistent with the pump manufacturer requirements for parti nlate material entrained in the fluid.
IIcad loss through the mesh screens is calculated assuming the maximum allowed flow from two tmins of ECCS with $0% surface aru clogging of the screens. The calculation used the methodology established by Diagram 8-6 in Section Vill in "Ilandbook of Hydraulic Pesistance, Coefficierc. of Local Resistance and of Friction", I. E. Idel'Chik,1960. Because of the large surface area, even with 50% clogging, the head loss would be less than 0.1 ft.
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6710-97-2$33 -
Page 2 of 3 2.
Identify the required NPSil and the available NPSH.
The required net positive suction head (NPSHa) is based upon the pump manufacturer's NPSH curves provided for the pump type installed at the site. The available NPSH4 is calculated for each pump based on the configuration for the train of equipment in which the pump operates. The calculation of available NPSH accounts for one 11ain of Low Pressure injection (LPI) and A
Building Spray (BS) taking suction from the RB Sump. If cither a LPI or BS pump is not operating then the available NPSHA for the other pump would increase because of the common suction line for cach train of equipment (i.e., im<cr head loss for lower common suction line flow).
Suction from the Reactor Building Sump
. 4,,
.. B" Pumps System Pump NPSHa NPSH NPSH A
A Flow' Flow.2 Low Pressure 2870 gpm 3020 gpm i1.078 ft 14.456 8 15.014 ft Injection (LPI)
Reactor Building j 1448 gp n
'1448 gpm 13.659 ft 14.710 fl 15.074 A Spray (BS)
Suction from a Pigr Back Source from the Reactor Building Sump Pumps System Flow Pump Flow NPSHa NPSH4 Suction (3)
(3)
Source High Pressure 954 gpm -
954 gpm
- 30 ft 312 ft LPI Injection (HD!)
Pumps Notes:
- 1. Accounts for instrument error.
' 2. Accounts for pump recirc"'.ation flow.
- 3. Based on three HPI pumps in operation.
_- ______i__________.__.___ _ _ _.. _ _.
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6710-9'/ 2533 Attachment i Page 3 of 3 3.
Specify whether the current design-basis NPS11 analysis differs from the most recent analysis reviewed and approved by thu NRC for which a safety evaluation was issued.
The most recent calculation for the LPI and BS pumps uses the same methodology approved in the SER allowing credit for overpressure equal to the vapor pressure of the sump liquid (i.e., h. =
h,,). The pump flow values were edjusted until the available NPSlir exceeded the required NPSila, accounting for instrument error and pump recirculation flow. A 10 CFR 50.59 evaluation of the adjusted flow values was performed to document the acceptability of the change. The plant procedures were modified to account for the new flow limits to satisfy the NPSH requirements.
4.
Specify whether containment overpressure (i c., containment pressure above the vapor prwure of the sump or suppression pool fluid) was credited in the calculation of availabk NPSH. Specify the amount of overpressure needed and the minimum overpressure available.
No credit is taken for containment overpressure in excess of the vapor pressure of the reactor building sump liquid.
5.
When containment overpressure is credited in the calculation of available NPSH, anfimi that an appropriate containment pressure analysis was done to establish the minimum containment pressure.
No credit is taken for containment overpressure in excess of the vapor pressure of the reactor building sump liouid. Therefore, containment pressure analyses were not required.
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