ML20134P830

Discusses Feedwater Line Water Hammer Issue for Licensee AP600 Advanced Reactor Design

ML20134P830
Person / Time
Site:	05200003
Issue date:	11/26/1996
From:	Diane Jackson NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9611290315
Download: ML20134P830 (3)

Text

_ _ _ _ . _ _ _ _ _ _ _ _ _ . _ _ _ _ . . _ _ _ _ . _

Tz -os 3

-g- pmaag h- p t UNITED STATES

!e 4

s j- NUCLEAR REGULATORY COMMISSION 2 WASHINGTON, D.C. 20086-0001 8

\*****p November 26, 1996 l

1 Mr. Nicholas J. Liparulo, Manager i Nuclear Safety and Regulatory Activities j Nuclear and Advanced Technology Division

Westinghouse Electric Corporation

, P.O. Box 355

{ Pittsburgh, Pennsylvania 15230 t

i

SUBJECT:

' FEEDWATER LINE WATER HAMMER ISSUE FOR THE WESTINGHOUSE AP600 ADVANCED REACTOR DESIGN

Dear Mr. Liparulo:

By letter dated November 4,1996, the Nuclear Regulatory Comission (NRC) staff provided our technical position on three issues in the Civil Engineering and Geosciences Branch (ECGB) review area. In recent conversations regarding that letter, Westinghouse requested additional information on the probability of a water hamer event and the application of leak-before-break (LBB) on feedwater lines to better understand the staff's conclusion. As requested, provided below is a discussion of the probability of a water hamer event on feedwater lines. It is our understanding that Westinghouse is preparing more detailed analysis to justify the application of LBB to feedwater lines.

Water hammer is not a rare event. In work for the NRC Office of Research by a professor at the Massachusetts Institute of Technology, a review of historical water hammer information taken from a 1992 EPRI report was provided (D. A.

VanDuyne, W. Yow, and J. W. Sabin, " Water Hamer Prevention, Mitigation and Accommodation. Vol. I: Plant Water Hammer Experience," EPRI Report NP-6766, July 1992). Of the 123 pressurized water reactor (PWR) water hamer events listed, 27 occurred in the feedwater system. Using a rough calculation of the number of effective full power years of PWR operating experience in the United States, it was estimated that the probability of occurrence of a feedwater system water hammer is about 1 event per plant over its operational lifetime.

The staff believes it is difficult to determine the magnitude of the water hamer loads that might be experienced on the AP600 feedwater lines, except in ,

a conservative, bounding sense. Water hamer is not a " normal" occurrence,  !

and, in general, results from either a mechanical malfunction or human error. I The magnitude of water hammer loads is a complex function of a number of }

mechanical and thermal-hydraulic factors, including system configuration and j fluid (water and steam) temperatures and pressures at the time of such an l event; given that water hamers (and the conditions that cause them) are i abnormal' occurrences, it is not practical to try to analyze the range of potential water hamer loads. However, if one assumes that cold water is l introduced into the feedwater system in the most unfavorable manner, and comes in contact with saturated steam at or near secondary side operating pressure, the aforementioned " conservative, bounding analysis" indicates that water 1 hammer pulses as high as 20,000 psi could result; the actual loads would \

probably be~somewhat less, h M.

290039 1 9611290315 961126 PDR ADOCK 05200003 EC FR.E CENTER COPY A PDR m i

Mr. Nicholas J. Liparulo November 26, 1996 i The staff does not believe that a finding that feedwater line water hammer is of " extremely low" probability can be justified and it appears that potential water hammer loads could be extremely high. Under the rules of the broadened scope of General Design Criteria (GDC)-4, for a piping system to be eligible for LBB, the probability of pipe rupture must be demonstrated to be extremely low by demonstrating adequate design consideration of several potentially direct and indirect pipe failure mechanisms, one of which is water hammer.

Westinghouse has incorporated features in the AP600 design that could reduce but not necessarily eliminate the occurrence of a water hammer. As stated in our November 4,1996, letter, since the potential for water hammer cannot be ruled out, and Westinghouse has not provided a quantitative analysis demon-strating an extremely low probability of this event, the staff has concluded that the criteria in GDC-4, i.e. the probability of pipe rupture due to water

hammer is extremely low, has not been met. The staff concludes that applica-i tion of LBB to the feedwater line for the AP600 is unacceptable.

If you have any questions regarding this matter, you can contact me at (301) 415-8548.

Sincerely, i

original signed by:

Diane T. Jackson, Project Manager

Standardization Project Directorate Division of Reactor Program Management 2

Office of Nuclear Reactor Regulation Docket No.52-003 l

cc: See next page DISTRIBUTION:

l Docket File - PUBLIC PDST R/F TMartin DMatthews TQuay TKenyon BHuffman JSebrosky DJackson JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11) Glainas, 0-7 D26 GBagchi, 0-7 HIS Shou, 0-7 H15 JBrammer, 0-7 HIS DOCUMENT NAME: A:LBB-FW.LET (9J fP@0 DISK) *E* = Copy with attachment / enclosure *N* = No copy Ta seceive a copy of this doewnent, indicate in the box: "C*f= Cph without attachment / enclosure 0FFICE PM:PDST:DRPM m l BC:Ef'GSfifE D:PDST:DRPM sl l l NAME DTJacksyn:sg D/ GBdchid TRQuay A 0/-

DATE 11/ M 96 /j ly/d96 11hD /967 ')#4L 0FFICIAL RECORDiCOPY

i .

b Mr. Nicholas J. Liparulo Docket No.52-003 4

Westinghouse Electric Corporation AP600 l cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director

! Advanced Plant Safety & Licensing Advanced Reactor Programs l Westinghouse Electric Corporation Nuclear Energy Institute  !

Energy Systems Business Unit 1776 Eye Street, N.W. i P.O. Box 355 Suite 300 i Pittsburgh, PA 15230 Washington, DC 20006-3706 Mr. John C. Butler Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs Mr. M. D. Beaumont GE Nuclear Energy Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 l Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz '

Suite 350 GE Nuclear Energy Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 Mr. Sterling Franks U.S. Department of Energy Barton Z. Cowan, Esq.

NE-50 Eckert Seamans Cherin & Mellott 19901 Germantown Road 600 Grant Street 42nd Floor Germantown, MD 20874 Pittsburgh, PA 15219 Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification Lockheed Idaho Technologies Company Electric Power Research Institute Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50 19901 Germantown Road 19901 Germantown Road Germantown, MD 20874 Germantown, MD 20874

_