ML20234E999

Nonproprietary Version of Addl Info in Support of Elimination of Postulated Pipe Ruptures in Pressurizer Surge Line of Vogtle Unit 2

ML20234E999
Person / Time
Site:	Vogtle
Issue date:	09/30/1987
From:	Palusamy S, Witt F WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19304B467	List: ML20234E957 ML20234E999
References
WCAP-11532-ADD, WCAP-11532-ADD-02, WCAP-11532-ADD-2, NUDOCS 8709220593
Download: ML20234E999 (17)

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J o WESTINGHOUSE CLASS 3  !

WCAP-11532 . J Addendum 2 .

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ADDITIONAL INFORMATION IN SUPPORT OF i

THE ELIMINATION OF POSTULATED PIPE RUPTURES IN THE PRESSURIZER SURGE LINE <

OF V0GTLE UNIT 2

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September 1987 S. A. Swamy  !

Verified by:

F.f. Witt Approved by:yde y $ h r4- - [

,- 5. 5/Palusamy, Manager Structural Material Engineering  !

Work Performed Under Shop Order GHFJ6502F 1

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~~ l WESTINGHOUSE ELECTRIC CORPORATION l Generation Technology Systems Division

. P.O. Box 2728

.Pittsburgh, Pennsylvania 15230-2728 l

8709220593 870917 '

PDR ADOCK 05000425- l A PDR 2625s-001687.10 I

TABLE OF CONTENTS Section Title Page

1.0 INTRODUCTION

1-1 2.0 ADDITIONAL INFORMATION 2-1 3.0 ALTERNATE ANALYSIS 3-1

/.0 CONCLUSIONS 4-1

5.0 REFERENCES

5-1 APPENDIX A - NRC REQUEST FOR ADDITIONAL INFORMATION A-1 e

2625s-091687 10

J SECTION'1.0.

INTRODUCTION The justification for eliminating dynamic effects of postulated pressurizer surge line ruptures for Vogtle Unit 2 was addressed.in WCAP-11531. At the request of the NRC additional information was provided in Addendum 1 to WCAP-11531. Upon review of this Addendum, the NRC staff requested further information and clarification (see Appendix A). A response-to this latter request is provided in this report, s

Section'2.0 provides additional justification for the applicability of the 1 toughness data used in WCAP-11531 and WCAP-11531,. Addendum 1 by extrapolation of lower bound J-T data obtained by. testing 1-T. specimens.

Section 3.0 provides limit load evaluations to verify crack stability using a 2-factor. approach as recommended by the NRC staff (see reference 3.)

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The conclusions are summarized in section 4.0.

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SECTION 2.0' ADDITIONAL INFORMATION

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l In reference 3, the NRC stated that the literature data used in the crack stability analysis must provide a reasonable lower bound for the welds at Vogtle Unit 2. Presented herein is a comparison of the data used (9.5T SAW) with lower bound data (IT SMAW) which demonstrates that the use of the 9.5T data is justifiable.

The data on SMAW welds based on testing IT specimens presented in reference 4-4 of WCAP-11531 can be considered as lower bound toughness data. The resulting test data are as follows:

2 JIc = 959 in-lb/in < 2 J,,x ~ 3000 in-lb/in ,

Tmat = 140 (corresponding to Jmax)*

The J versus T for these data is plotted in figure 1. These data can be extrapolated to higher values of J as described in NUREG 1061, Volume 3.

Based on extrapolation (see figure 1), the tearing modulus corresponding to a J value of 6000 in-lb/in2 is found to be 88. The maximum recommended extrapolation is 2 times the highest J 1evel where valid data are available.

If, however, the extrapolation is further extended by a small amount (i.e. up 2

to J = 6600 in-lb/in ), the tearing modulus would be 78 corresponding to J = 6600 in-lb/in 2, A comparison of the IT data on SMAW welds (extrapolated) with the 9.5T data used in WCAP-11531 is shown below- .

IT data extrapolated

1) Tearing modulus = 88 corresponding to J = 6000 in-lb/in2

2) Tearing modulus = 78 corresponding to J = 6600 in-lb/in 2 9.5T data used in the calculations of WCAP-11531 and 11531 Addendum 1

1) Tearing modulus = 76 corresponding to J = 6000 in-lb/in 2

2) Tearing modulus = 74 corresponding to J = 6600 in-lb/in 2 2625s-091687.10 m o _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ __ _

' Based on'the above, it is apparent that the toughness allowables used for demonstrating flaw ' stability in WCAP-11531 are~ comparable to the lower bound

~ data on the SMAW welds obtained by using the IT. specimens and are therefore  ;

justified. Using.this data,-a [' Ja,c,e long through-wall flaw was I shown to be stable when subjected to (normal plus SSE) loads. .Also, a (

Ja,c,e.long through-wall flaw:was shown to be stable when subjected to  !

1.4 (normal plus SSE) loads.

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.The postulated crack length of [' Ja,c e yields a leak rate of 10' )

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FIGURE 1: J VERSUS T CURVE FOR SMAW KILOS SHOWING EXTRAPOLATION

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SECTION 3.0 ALTERNATE ANALYSIS As stated in reference 3, a limit' lead analysis may ' eb performed as an alternative to performing a J-T stability evaluation. Using this approach a limit ~1oad analysis was performed for the Vogtle surge line. A plot of the limit moment versus crack length is provided.in figure 6-3 of WCAP-11531 for

! - the base _ metal. The plot is reproduced here (figure 2) for ready reference. t

From this figure it is seen that the critical flaw size is calculated to be

-[ .Ja,c,e using the minimum tensile properties for SA376 TP316

, (wrought)Lstainless. steel (base metal). A "Z" factor correction for SMAW welds was applied (references l3 and 4) as follows:

2 =-1.15 [1.0 + 0.013 (DD-4))

where OD is the outer diameter of the p'ipe in inches.

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. Substituting OD = 16 inches, the Z factor was calculated to be 1.3294. The applied loads were increased by the Z factor and the plot of limit load versus crack length was regenerated as shown in figure 3. The lower bound base metal properties' established in WCAP-11531 were used for this purpose. From figure 3, the critical flaw size is seen to be [ Ja,c.e long. Noting that

-the flaw' yielding a leakage of 10 gpm (leakage size flaw) was calculated to be

-[ ]a,c.e long (reference 1), a factor of 2.6 exists between the leakage size flaw and the critical flaw. Thus, a' margin of greater than 2 on flaw size is in evidence.

In order to determine the margin on applied loads (normal plus SSE), the applied loads were increased by a factor of 1.8612 (i.e. 1.4 Z) and the plot of . limit load versus crack length was generated as shown in figure 4. Again the lower bound base metal properties were used for this purpose. From figure 4 the critical flaw size is seen to be [ ]a,c,e inches long which is larger than the [ Ja,c.e long leakage size flaw. Thus, a margir, greater than 1.4 on (normal plut $5E) loads is demonstrated. This analysis also supports the validity of the J-R curve discussed in section 2.0.

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FIGURE 3: CRITICAL- FLAW SIZE PREDICTION BASED ON 2 TIMES MAXIMUM LOAD un, w w ,o 3~3

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i i-FIGURE 4: CRITICAL FLAW SIZE PREDICTION BASED ON 1.4 2 TIMES MAXIMUM LOAD 3-4 2621s-091687 10

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SECTICN 4.0 l CONCLUSIONS ]

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Alternate calculations were performed using the'"2" factor: approach as 1 described by the NRC. staff in reference 3. The results of alterndte -

-calculations for stability indicate that a margin of at least 2 with respect '

to the lea'k age size flaw exists. Also, a margin of a factor of at least 1.4 exists with respect to.(normal plus SSE) loads. A margin of 10 with respect to leak detection capability is also met. Based on the above, and information q provided in references 1 and 2, it.is concluded that dynamic effects from j postulated pressurizer-surge line breaks need not be considered in the structural design basis of Vogtle Unit 2.

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il SECTION 5.0 REFERENCES'

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1. Swamy; 15. A., et .al., " Technical Bases for Eliminating Pressurizer Surge Line' Rupture as the Structural Design Basis for Vogtle Unit 2,"

WCAP-11531, July-1987-(WestinghouseProprietaryClass2).

2. Swamy, S. A., et al., " Additional -Information in Support of the

~ Elimination of Postulated Pipe Ruptures in the Pressurizer Surge Line of Vogtle Unit 2"lWCAP-11531 Addendum 1, August 1987 (Westinghouse Proprietary Class 2).

, '3. NRC letter' from M. A. Hiller to Georgia Power Company, J. P. O'Reilly, dated September 9,1987.

4. ASME Code Section XI, Winter 1985 Addendum, Article IWB-3640.

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APPENDIX A e

H NRC REQUEST FOR ADDITIONAL INFORMATION i

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UNITS 0 STATES ,

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%,' .'.M SEP 0 8 1987 Docket No.: 50-425

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Mr. James P. O'Reilly Senior Vice President - Nuclear Operations Georgia Power Company P. O. Box 4545 Atlanta, Georgia 30830

Subject:

Request for Additional Information on Dynamic Effects of Postulated Pressurizer Surge Line Pipe Ruptures from Design Basis for Vogtle Unit 2 I By letter dated July 15, 1987 Georgia Power Company (GPC) submitted the l

technical basis for the elimination of the dynamic effects of postulated <

• pipe ruptures in the pressurizer surge line of Vogtle Unit 2 in Westing- I house report WCAP-11531. 'On the basis of its review of this report, the 1 staff requested additional information by letter dated August 6.1987. I In response. GPC submitted Addendum 1 to WCAP-11531 by letter dated I August 19, 1987. The staff has reviewed GPC's submittals and finds that l insufficient additional information was provided for the flaw stability

-evaluations. A request for additional information is enclosed. 1 Sincerely, Melanie A. Miller, Project Manager Project Directorate II-3 Division of Reactor Projects. I/II

Enclosure:

As stated e

cc: See next page A-2 2625s 091687 to

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1 INCLOSURE I

REQUEST FOR ADDITIONAL INFORMATION ON ELIMINATION OF POSTULATED PRESSURIZER SURGE LINE RUPTURES.

AS A DESIGN BASIS-GEORGIA POWER COMPANY 3

V0GTLE ELECTRIC GENERATING PLANT UNIT 2 l DOCKET NO. 50-425 '

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ly letter dated July 15, 1987, Georgia Power Company (the applicant) submitted the technical' basis for the elimination of the dynamic effects of postulated pipe reportruptures WCAP-11531. in the pressurizer surge line of Yogtle Unit 2 in Westinghouse By letter dated August 19, 1987, the applicant submitted Addendus 1 to WCAP-11531 in response to the staff's request for add,itional information in'a letter dated August 6,1987. The staff has reviewed the submittals and finds that insufficient additional infomation was provided for the flaw stability evaluations, i

On pages 2 through 4 of Addendum I to WCAP-11531, the applicant discussed the fracture toughness properties of welds. The applicant used the fracture  :

• toughness data from the literature in Figure 4-4 of WCAP-11531 in the flaw stability analyses. The applicant contended that the "9.5T" submerged arc weld ($AW) specimen data in Figure 4-4 of WCAP-11531 provided a lower bound for the shielded metal arc welds ($ MAW) in the surge line of Vogtle Unit 2.

However, the applicant did not provide sufficient Justification for the application of the.aingle set eFMt data from the literature. The literature data used in the fracture staM11ty analysis must provide a reasonable lower bound for the welds at Vogtle Unit 2. .

Comparing the applicant's referenced fracture toughness data with these subn:itted by another applicant, the staff finds that the data in Figure 4-4 of WCAP-11531 are not lower 40und values for $AW, or even for $ MAW. The staff is aware that the planform sire of the test specimen affects the toughness data.

However, the toughness values.for small crack growth should be less affected by the planform size than those for large crack growth. The staff compared  ;

the toughness data in Figure 4-4 of WCAP-11531 with lower-bound toughness values submitted by another apg11 cant and found that the fracture toughness "J" values for the referenced 9.57" SAW specimen were approximately 355

, larger than the lower-bound values for $ MAW for small crack growth. Since the applicant did not provide sufficient justification for the application of the data in Figure 4-4 of WCAP-11531, the staff finds that if the "9.57" specimen data are to, be used in the fracture stability analyses of SMAW, the "J" values 2626s 091687.10 A-3

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should be reduced by greater than 355 to ensure that the estimated fracture toughness Unit "J" resistance curve would be a reasonable lower bound for Vogtle

2. Thus, a 405 reduction in the "J" values of the "9.5T" specimen data in Figure 4-4 of WCAP-11531 would be acceptable to the staff. Furthermore, this method of extrapolation of the "J" resistance curve should be limited to a crack growth of less than 0.5 inch. Unless the applicant provides adequate o justification literature, thisby reduced referencing "J a sufficiently large number of data from the resistance curve should be used for SMAW.

On page 6 of Addendum 1 to WCAP-11531, the applicant contended that the margin of 1.4 on the loads should not be applied because of the method of load combination. However.. it is the staff's current position that the margin of 1.4 and the method. of load combination described in NUREG-1061 Volume 3 are required. Thus, the margin of 1.4 on the loads must be applied.

The applicant should reevaluate the flaw stability tearing modulus (J-T) analyses using the reduced "J" resistance curve. If significant crack growth is predicted, the effects of crack growth should be considered in an

• decremental crack growth anal sis. The applicant should demonstrate the t stability of a through-wall f aw at least twice the size of the leakage-sise i flaw under combined normal and safe shutdown earthquake ($5E) loads. Also.

the applicant should demonstrate the stability of the leak e-size flaw if the loads loads. are increased to at least 1.4 times the combination o normal and SSE I

As an alternative to performing a M flaw stability analysis as discussed above, the applicant may perform a limit load analysis. However, the applied loads must be increased by a factor corresponding to the type of the flux weld. The "Z-factor" correction for flux welds is the basis for developing allowable flaw sizes for austenitic steel piping in Article IWB-3640 of the Winter 1985 Addendum of Section XI of the ASME Code. Specifically, for SMAW.

"Z" = 1.15 ( 1.0 + 0.013 ("0D" - 4) 3, where "0D" is the outer diameter of the pipe in inches. Also, the lower-bound flow stress of the base metal should be used in the limit' load analysis. Thus, in parforming a limit lead analysis, the applicant should demonstrate the stability of a through-wall flaw at least

-twice the size of the leakage-size ' flaw if the loads are increased to "Z" times the combination of normal and SSE loads. Also, the applicant should i i

demonstrate the stability of the leakage-size flaw if the loads are increased to at least.k4 "I' times the combination of normal and $$E loads.

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