ML20059E064

Nonproprietary Suppl 3 to Evaluation of Pressurizer Surge Line Transients Exceeding 320 F for Beaver Valley Unit 2

ML20059E064
Person / Time
Site:	Beaver Valley
Issue date:	07/31/1990
From:	Tilda Liu, Valasek L, Witt F WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19302E171	List: ML20059E057 ML20059E060 ML20059E064
References
WCAP-12094-S03, WCAP-12094-S3, NUDOCS 9009100015
Download: ML20059E064 (15)

Text

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. WSTINGHOUSE CLASS 3 WCAP-12094 Supplement 3 EVALUATION OF PRESSURIZER SURGE LINE TRANSIENTS EXCEEDING 320'F FOR BEAVER VALLEY UNIT 2 l

July 1990 .

T. H. Liu F. J. Witt  :

L. N. Valasek I Verified by: // , Verified by: [ _

K. C. Eh'ang E. 'L. CraMord Apriaved by:

b*b Approved b , ,. < rl C.nte,d R. F. Patel, Manager D. C. Adamonis, Systems Structural Acting Manager, Analysis and Development Structural Mechanics Technology 1

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WESTINGHOUSE LETTER DATED 8/30/90 FROM R. WEISMANN TO 9OCKET CONTROL DESK, USNRC, GRANTS NRC PERMISSION TO COPY NON-PROPRIETARY DOCUMENTS RECEIVED PRIOR TO 12/31/90 l

WESTINGHOUSE ELECTRIC CORPORAT!CH l Nuclear and Advanced Technology Division P.O.. Box 2728 Pittsburgh, Pennsylvania 15230-2728

, e 1990 Westinghouse Electric Corp.

'9009100015 900810 , .

PDR ADOCK0500p,g. -

P . _ . . . . . 4.h

This nonproprietary report bears a Westinghouse copyright notice. The NRC is permitted to make the number of copies of this report necessary for its intertal use and such additional copies which are necessary in order to have one copy available for public viewing in the appropriate docket files in the public document room in Washington, D. C and in local public document rooms i as may be rwyeired hv NRC regulations if the number of copies submitted is l insufficient for this purpo:e. The NRC is not authorized to make copies for I the personal use of members of the pablic who make use of the NRC public document rooms. Copies of this report or oortions thereof made by the NRC must include the copyright notice.

l TABLE OF CONTENTS Section Title Page  ;

1.0 INTRODUCTION

1 2.0 TRANSIENT DEF:NITION 2 ,

3.0 ASME SECTION Ill STRESS ANALYSIS AND FATIGUE USAGE 3 FACTOR EVALUATION 4.0 FATIGUE CRACK GROWTH EVALUATION 4

5.0 CONCLUSION

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6.0 REFERENCES

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'I LIST OF TABLES I

Table Tit 1e Page-I 4-1 Fatigue Crack Growth For Forty Year Service for a 10% 5 Through-Wall Crack Including the Fivi Cycles of the l

[ .)a,c,,  !

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LIST OF FIGURES Figure ti+1e F 4.ge 4-1 Pipe Locations at Which the Fatigue Crack Growth 6 Was Performed 4-2 Circumferential Position ( Ja.c.e at Each Location at 7 Which Cracks were Postulated for Fatigue Crack Growth Evaluations 4

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1.0 INTRODUCTION

Thermal stratification for the pressurizer surge line of Beaver Valley Unit 2 was addressed in WCAP-12093 and its two supplements (References 1, 2 and 3).

The primary conclusions of the surge line evaluations are that thermal stratification has limited impact on the integrity of the pressurizer surge line of the Beaver Valley Unit 2 nuclear powei slant and that the forty year design life is not impacted. These conclusions are based on the current understanding of the thermal stratification phenomenon.

Subsequent to the evaluations and reports, a system temperature difference of near ( Ja,c,' was experienced. This supplement to WCAP-12073 incorporates the ( Ja,c.e transient into the integrity evaluation of the surge line.

Specifically, the impacts of the transient on stress intensities, cumulative usage factors and fatigue cract growth are evaluated.

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2.0 TRANSIENT DEFINITION The characteristics of the thermal stratification transie:'s were discussed in WCAP 12093. Of significance to this evaluation is that, F sed on historical data associated with a high system temperature difference, is a [

la.c.e. the original temperature differences addressed in WCAP-12093.

In summary, (

3a,c.e 2 l l

o 1 3.0 ASME SECTION 111 STRESS ANALYSIS AND FATIGUE USAGE FACTOR EVALUATION The ASME section !!! equation (12) stress intensity and cu4lative usage factor were c?lculated at the worst location (i.e., the surge line branch nozzle at the hot leg) for the new postulated transients defined in section 2.0. This new transient scenario, which is considered more severe than the one described in WCAP 12093, is postulated to consist of [

Ja c.e in addition to all the transient cycles defined in WCAP 12093. For the global bending effects of thermal stratification, the pipe cross section is stratified between the outside surfaces of the top and the bottom for a given AT. ('

i Ja.c.e The refined calculation also considered that (

la.c.e as justified by the surge line monitoring data from Westinghouse Owners Group. By removing these two areas c.' i conservatisms from the structural responses presented in WCAP 12093, these calculations demonstrated that the maximum eq, ; ion (12) stress in the WCAP remains valid for a system delta i of ( ) a,c.e Hence the new equation (12) stress intensity is still at ( .]C ksi comparing to the code allowable value of 55.5 ksi at the hot leg nozzle location.

Fatigue usage factors for the Beaver Valley Unit 2 surge line were evaluated for the new postulated transient condition, based on the requirements of the ASME section !!! code. A detailed analysis was performed at the worst locution to account for the additional cycles and higher AT from the calculation made in WCAP 12093. The analysis shows that the new cumulative usage factor is

( Ja.c.e for the 40 years of design life of the Beaver Valley Unit 2 plant.

Since this calculation is at the worst location on the surge line it it concluded that the new usage factor at other locations due to the increase in cycles and AT will be less than the value of ( Ja.c.e

. Therefore, both the ASME code equation (12) stress intensity and the fatigue cumulative usage factor are acceptable considering the thermal stratification  !

condition defined in section 2.0.

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4.0 FATIGUE CRACK GROWTH EVALUATION in reference 1 the sensitivity of the pressurizer surge line to the presence

small cracks when subjected to the transient developed in that report was evaluated by performing fatigue crack growth analyses. Cracks having a six-to-one aspect with an initial depth of 10% of the wall thickness were postulated to exist at five pipe locations in the surge line. Analyses were made for postulated cracks at four circumferential positions at each location. The five locations are shown in Figure 4-1 and the four positions at which cracks were postulated are shown in Figure 4-2. It was found in WCAP 12093 that the largest amount of fatigue crack growth occurred at position ( la.c.e for each of the five locations.

The fatigue crack growth was re-evaluated at position (- Ja,c.e at each of the five locations accounting for the transients associated with the

( Ja,c.e temperature difference as discussed in Section 2.0. The results are shown in Table 4-1. The crack extensions only slightly exceed those reported in WCAP 12093. The maximum depth for ful' ervice life and including the transients of Section 2.0 remains less than 25% of the wall.

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TABLE 4-1 Fatigue Crack Growth for Forty-Year Service i for a 10% Through-Wall Crack including Five Cycles -

of the [ Ja.c.e ,

Final Crack location Initial Crack. Final Cr6ck~ Depth Percent Depth (In.) Depth (In.) of Wall

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"'C i 1 0.141 '

2 0.141 ,

3 0.141 r

4 0.141 5 0.141 k

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a,c.e I

Figure 4-1 Pipo Locations at Which the Fatigue Crack Growth Was Performed 6

a,c.e 1

Figure 4-2 Circumferential Position ( Ja,c.e at Each Location at Which Cracks Were Postulated for fatigue Crack Growth Evaluetions 7

5.0 CONCLUSION

S Stress intensity, cumulative usage factor and fatigue crack growth evaluations were performed for the pressurizer surge line of Beaver Valley Unit 2 which accounted for a specific transient to ( Ja c.e The maximum stress intensity, fatigue usage factor and growth of postulated cracks are not significantly impacted by the transient to (- Ja.c.e These results reaffirm that, for the case at hand and based on the current understanding of the thermal stratification phenomenon, thermal stratification has limited impact on the integrity of the Beaver Valley Unit 2 nuclear power plant and that the forty year design life is not impacted, as concluded in WCAP 12093, b

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6.0 REFERENCES

1. R. L. Brice-Nash et. al., Evaluat.. ) of Thermal Stratification for the Beaver Valley Unit 2 Pressurizer Surge Line, WCAP-12093, December 1988.

2. F. J. Witt, Additional Information in Support of the Evaluation of Thermal Stratification for the Beaver Valley Unit 2 Pressurizer Surge Line, WCAP-12093, Supplement 1, February 1989.

3. E. L. Cranford et. al., Additional Information in Support of Thermal Stratification for the Bsaver Valley Unit 2 Pressurizer Surge Line, WCAP-12093, Supplement 2, August 1989.

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