ML20134B375

Discusses Application of leak-before-break Methodology to Feedwater Line in W AP600 Advanced Reactor Design

ML20134B375
Person / Time
Site:	05200003
Issue date:	01/24/1997
From:	Martin T NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9701300063
Download: ML20134B375 (3)

Text

._ _ _ _ _. _

,a eur

' g UNITED STATES NUCLEAR REGULATORY COMMISSION g*****,/j-p*

WASHING 1roN, D.C. 200864001 i

January 2t, 1997 L

q.

'Mr. Nicholas'J. Liparulo, Manager l

Nuclear Safety and Regulatory Activities Westinghouse Electite Corporation l

Pittsburgh, PA 15230

SUBJECT:

THE APPLICATION Of LEAK-BEFORE-BREAK (LBB) METHODOLOGY TO THE i

l FEEDWATER LINE IN THE WESTINGHOUSE AP600 ADVANCED REACTOR DESIGN l

Dear Mr. Liparulo:

i In a_ meeting between the Nuclear Regulatory Commission (NRC) staff and l

Westinghouse on December 5,1996, the staff committed to reconsider a Westing-house proposal to apply LBB methodology to the feedwater line in the AP600 j

advanced reactor design. To date, no operating reactor or advanced reactor design has been approved for the application of LBB on the feedwater system.

This issue is documented in NRC requests for additional information and in the i

draft safety evaluation report (DSER) issued in November 1994.

In the DSER, the staff stated that the application of LBB to the feedwater line was unacceptable. After the DSER was issued, the staff and Westinghouse continued to hold extensive discussions on this issue.

In the course of these discus-i sions, the staff raised many concerns regarding the application of LBB to the feedwater line. These concerns included: consideration of water hammer events, thermal stratification, fatigue, erosion / corrosion, and a lack of i

operating experience with the new AP600 feedwater system design.

i The staff recognizes that Westinghouse has made significant improvements in L

the proposed feedwater system design to address these concerns in an attempt i

to qualify the system for LBB consideration. However, the staff's concerns have not been completely eliminated. Two complementary unresolved issues j

remain:

(1) the lack of operating experience with the redesigned feedwater system and frequency an(d magnitude of water hammer events.2) the uncertainty that exists in acc i

i The staff has considered all of Westinghouse's proposals and analyses to evaluate the application of LBB methodology to the AP600 plant on the basis of its technical merits. The approval of the application of LBB to a system is based on demonstrating that the probability of a rupture in a fluid system pipe is extremely low. This, in turn, requires a thorough understanding of the' dynamic loadings that may occur in the system, their frequency of occur-4 rence, and the ability to conservatively predict the magnitude of the load-i ings.

It is the staff's position that the lack of operating experience with the feedwater system as redesigned for AP600 significantly deters our ability i

to predict the frequency or the magnitude of water hammer events in the AP600.

Therefore, it is not possible to predict the likelihood of occurrence of a water hammer event that could invalidate the assumptions of LBB or cause the unanticipated failure of the feedwater line. The staff finds that, at

(

DFDD o

^'

9701300063 970124 PDR ADOCK0520g3 gg g{(

hf

3 w

s T

- s r.

e i

j

,' i 4,

Mr. Nicholas:J.;Liparulo

_ January 24, 1997 4

.*s

.o t

.s u

3.

./ this$ time,. Lit cannot! conclude that' a'n " extremely low" probability of pipe

< ruptureiexists<for the AP600 feedwater system, as is required by 10 CFR Part50, Appendix'A,iGeneralDesignCriterion4.

Ther fore,' the$ staff must deny the Westinghouse proposal to apply the LBB

~

methodology /to~ the AP600 feedwater line.

It is the position of the staff j that ' operating experience.with this system is necessary before any other

.% conclusion can be reached. - Accordingly, the staff does not plan to expend any additional resources on this issue.

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

1 Sincerely, original signed by:

Thomas T. Martin, Director Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 i

cc:

See next page DISTRIBUTION:

PDST R/F TMartin Docket File..

DMatthews TQuay PUBLIC TKenyon WHuffman JSebrosky DJackson JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11)

BSheron, 0-12 E22 GHolahan, 0-8 E2 TMartin, 0-11 H21 Glainas, 0-7 D24 JStronsnider, 0-7 D24 GBagchi, 0-7 H15 Shou, 0-7 H15 JBrammer, 0-7 H15 TCollins, 0-8 E23 Alevin, 0-8 E23 KWichman, 0-7 D4 DTerao, 0-7 04 BElliott, 0-7 D4 MMitchell, 0-7 D4 i

EHackett, T-10 E10 LLund, T-10 E10 DOCUMENT NAME: A:LBB-FW2.L

• See previous concurrence n m. n.e w. 4

. me w.TR

. w c. cm e.oi.n nu.new.=

r - con e.unn ou.=w..

r - wo em 0FFICE-PM:PDST:DRPM__-l D:PDST:DRPM D:DE l

AD:ADTl 0:DPyrik NAME DJackson:sg ??

TRQuay*

Glainas*

BSheron*

TTfartin W

01/13/97 01/17/97 01/21/97 01/24/97 DATE Ol M /97 0FFICIAL RECORD COPY

)

j e

j g

8 u

. s.

e

i e

i l'

Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director Advanced Plant Safety & Licensing Advanced Reactor Programs 4

Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 Eye Street, N.W.

P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706 Mr. John C. Butler Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates 1

Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 j

Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs l

Mr. M. D. Beaumont GE Nuclear Energy j

Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz Suite 350 GE Nuclear Energy i

Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 Mr. Sterling Franks U.S. Department of Energy Barton Z. Cow 3n, Esq.

i NE-50 Eckert Seamans Cherin & Mellott 19901 Germantown Road 600 Grant Street 42nd Floor l

Germantown, MD 20874 Fittsburgh, PA 15219 Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification i

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 4

s i

4 t

,n

.