ML20101B313

Submits Results of RHR Heat Exchanger Inservice Insps. Results of Analysis Confirm That RHR Heat Exchangers Acceptable,Without Repair,For Continued Svc

ML20101B313
Person / Time
Site:	Byron
Issue date:	05/27/1992
From:	Chrzanowski D COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9206010304
Download: ML20101B313 (44)

Text

_. _ _ _ _

4 e-N 1Cammsnwealth Edis:n

)-

O / 1400 Opus Place j

n C

Downers Grove, Illinois 60515 May 27,1992 '

t l

Dr. Thomas E. Murley, Director-Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission l

Washington, DC 20555 l

Attention: Document Control Desk

Subject:

Byron Unit 2 Residual Heat Removal Heat i

Exchanger Inservice Inspection Results-Byron Un't 1 and 2,

{

NRC Docket Numbers 50-454 and 5 455

Dear Dr. Murley:

1-1 The purpose of this letter is to transmit the results of Byron Unit 2 Residual Heat' Removal (RHR) heat exchanger inservice ins sections.. During these examinations, indications were detected in the RHR nozzel-Lo-vessel welds. These indications were l

evaluated using a previously NRC approved ASME Section XI fracture mechanics methodology, i

The results of this analysis confirm that the RHR heat exchangers are I-acceptable, without teaalr, for continued service. The results of the inspection were verbally provided to N30 staff in a April 15,1992 teleconference. The details of the Inspection and analysis results are contained in the attachments.

if there are any questions or comments, please contact me at (708) 515-7292. -

Sincerely, 4

David J. Chrzanowski

. Nuclear Licensing Administrator Attachment A - Ultrasonic Indication Summary-

- Attachment B - Westinghouse Fracture Mechanics Evaluation.

cc:

A. Bert Davis, Regional Administrator-Rill R. Pulsifer, Project Manager-NRR/PDill-2 i

e A. Hhla, Pr ct Manager-NRR/PDlll-2 i

S. DuPont, raidwooc) w/o attachments 1

W. Kropp,-( yron) w/o attachments

\\ p'g -

9206010304 920527 PDR ADOCK 05000454 l-G PDR-

.I l

5 ZNLD/1788/3

=

-. -.=--.-.-.

..a

+- -. -

4 A.TTACHMENT A BYRON UNIT 2 REFUEL OUTAGE B2R03 RHR HEAT EXCHANGER NOZZLES ULTRASONIC INDic ATION

SUMMARY

ZNLD/1788/4

1)

BACKGROMED Byron requested relief (Preservice Relief Request NR-13) from the NRC during Preservice Inspection for tne volumetric examinations for the Residual Heat Removal Heat Exchanger-(RHR) nozzle to vessel welds.

The basis behind the request was due to the geometric restraints in performing the examination as a result of the configuration of the nozzlo to vessel welds.

The configuration of the nozzle is such that construction did not allow for relevant volumetric examination as the installation utilizes an internal reinforcing pad and a double bevel groove weld with a fillet reinforcement.

The relief request was granted.by the NRC and documented in their review of the Unit 2 Byron Preservice Inupection Program Dccket # 50~455, SSER 7 Appendix K.

Byron requested similar ruilef for the Inservice Inspection program via submittal of Inservice Relief Request NR-12.

This request for relief aought the same exemption for volumetric examinations of-the nozzle to vessel welds and inner radius that had been granted during Preservice.

This relief was granted for the inner radius inspection but requested that a "best effort" volumetric examination be performed on the nozzle to vessel welds.

This is documented in the NRC Safety Evaluation of the Byron Units 1 and 2 First Ten Year Interval Inservice Inspection Program (Docket Numbers 50-454 and 50-455, TAC 60703).

It should be noted that Braidwe'd had previously performed these examinativas on their Uaic 2 RHR Heat Exchangers in November of 1991 in response to their like Relief Request and identified the existence of numerous indications attributed to manufacturing defects.

Braidwood solicited Westinghouse Corporation to perform a Fracture Mechanics Analysis in accordance with ASME Section XI IWB-3500 and/or IWB-3600.

The analysis was initiated for both Byron and Brai$ wood Units 1 and 2 RHR Heat Exchangers Nozzles and subsequently, this methodology was accepted by the NRC for application at both Byron and Braidwood in Docket No. STN 50-457.

This analysis (Westinghouse Report RMDT-SMT-062) accepted the-existence of f1cws-up to and including 60% of the thickness of the material at the flaw location, extending 360* and surface connected.

The analysis accepted these types of flaws for the entire 40 year service life of the vessel.

l 2)

INTRODUCTION 1

l Pursuant to the NRC response to Inservice Relief Request NR-12, a "best effort" ultrasonic examination was conducted on the Byron Unit 2 RHR Heat Exchanger nozzle ta vessel welds.

Reference Figure 1 for the inservice inspection weld locations.

During Byron Refueling Outage B2R03 the Unit 2 "B" RHR Heat Exchanger Outlet nozzle to vessel weld was scheduled for examination.

Ultrasonic relectors were identifed in excess of 100% DAC (Distance Amplitude Correction) reference levels with definable depth.

These indications were evaluated and determined to be in excess of the acceptance criteria defined in IWB-3500.

The examination were expanded to include the

f a

(

s "B"

Inlet nozzle where similar indications in excess of IWB-3500 were recorded.

Ultimately, all four Unit 2 RHR nozzle to vessel welds were examined and indications in excess of IWB-3500 were identified.

These indications were sized and all were determined to be within the Westinghouse Fracture Mechanics Analysis performed for the Byron and Braidwood RHR Heat Exchangers and were determined to be acceptable-for continued service.

These indications are consistont with the (ndications found at Braidwood and are consistent with slag.nclusions and/or lack of fusion in the fabrication process and are not service induced flaws.

As shown in this report all indications are within ASME Section XI subarticle acceptance standards providad in IWB-3500 or IWB-3600.

These indications which were found to be acceptable analytically by the Fracture Mechanics Analysis will be monitored by exacinations that will be conducted in future Byron Unit 2 Refueling Outage as required by ASME Section XI IWC-2420.

3)

FABRICATION INFORMATIQH The subject nozzles are on the tube side of the PHR Heat Exchangers.

These heat exchangers were manufactured by Joseph Oats Corporation in 1975 in accordance with ASME Section III, NC-3200 Alternate Design Rules for Vessels.

The heat exchanger vessel tube side is ASME Class 2 and the shell side is ASME Class 3.

The nozzles are 3 (actual measured ultrasonic thickness is/8" nominal thickness

.400"),

13.875 inch.s outside diameter, SA-240 TP304 rolled plate welded to the 1 inch thick SA-240 TP304 rolled plate of the tube side vessel wall.

The weld configuration as shown in Figure 2 is a double bevel groove weld with an external 3/8" nominal fillet weld reinforcement.

The welding process was performed using the shielded metal arc process with E308 electrodes.

Joseph Oat i

personnel and their fabrication procedures indicate that the l

groove weld was backgouged at the root pass (es) during the l

welding process.

The inside and outside surfaces of the I

welded joints were examined by the liquid penetrant method at the completion of welding.

The welds were not radiographed during fabrication as due to the joint configuration.

ASME Section III, 1974 Edition, NC-3352 does not require radiographic examination of angle joints between the shell and nozzle which exceed 30*.

The ultrasonic examinations performed during this outage were the first volumetric examinations of these welds.

l 4)

ULTRASONIC TECHNIOUES The RHR heat exchanger nozzle to vessel welds were examined using a procedure that required a calibration which would produce an examination that meets the intent of ASME Section XI Appendix III requirements.

The examinations were conducted utilizing EBASCO NDE Procedure BY-UT-S83-1 Rev 1., Addendum 1.

This procedure

s allowed the use of a 70*,

5.0 mhz,

" dia. shear wave transducer.

This transducer was necessary to obtain the best examination coverage and sensitivity possible.

In conjunction with this procedure, depth sizing of the identified indications were performed in accordance with CECO procedure NDT-C-41 Rev.

O.

This procedure allows the use of High Angle Dual-Refracted Longitudinal Wave Transducers to determine the thru-wall dimensions of the flaw indications.

The following requirements applied while using the above referenced procedures:

a)

The circumference of the nozzle welds were marked at 1"

+

increments.

b)

All flaw indications that were detected at 25% DAC or greater amplitude within each inch of weld were reported.

c)

If the flaw indication was not detected at 25% DAC level within each inch of weld, it was considered terminated, d)

If the flaw indications appeared continuous or intermittent between termination points, this was noted or recorded.

e)

Flaw indications in excess of 100% DAC were length sized in accordance with ASME Section XI or 100% DAC end points and their depth were sized in accordance with CECO procedure NDT-C-41, Rev.

O.

f)

The 70' shear wave transducer was used to size the

)

length and to record the indications around the circumference, g)

Indications which exceeded 100% DAC were sized using the 70' shear, 70RL, and 60' shear transducer.

h)

Indications which exceed ASME Section XI IWB-3500 acceptance criteria will be monitored in future refueling outages as required by ASME Section 'XI, IWC-2420.

5)

ULTRASONIC EXAlil1%T_10N RESULTS Attachment A summarizes, for each nozzle, the recordable indications detected during ultrasonic examinations.- One indication identified on the outlet nozzle for the A RHR Heat exchanger was noted to be I.D. connected and is so noted on the attached tables.

The-remaining flaws-were found not-be surface connected, however following the methodology of ASME Section XI, IWA-3310(h), several flaws have been considered as surface flaws and are so noted on these tables.

The a/t column values were established based on the nozzle wall thickness (.400") unless so noted where the fillet reinforcement thickness at the flaw location was considered for those flaws.

The tables and graphs are noted for these.

Indications.

3 s

6)

EVALUATION OF ULTRASONIC EXAMINATION'RESULTE.

The Fracture Mechanics = Analysis previously referenced in this report was performed =by Westinghouse in accordance with the methodology and criterla provided in ASME Section XI'IWB-3600.-

This evaluation developed maximum--allowed flaw dimensions'for normal operating conditions and emergency and faulted conditions.

The results of the Fracture Mechanics i

Analysis has been used to develop an upper boundary flaw chart for the recorded indications. - The complete-Westinghouse analysis which developed this criteria is attached to this report.

Figure.4-1 in the Westinghouse

?

Analysis shows the developed chart.

All indications from section 5 which were found to be 2.i excess of-the criteria in IWB-3500 have been found to be within the Fracture Mechanics Analysis allowable limits. :The indications for each nozzlo have been plotted on separate flaw charts.

Thesa charts are provided in attached Figuru. 3 thru 6.

The 1/c values for those charts were developed using the outside diameter of the nozzle of 13.875" resulting'in an outside circumference of 43.6".-

-l 7)

PRIMARY COOLANT WATER CHEMISTRY-The RHR heat exchanger tube side nozzles are exposed to only primary coolant unter.

The Chemistry requirements-for primary coolant water are provided in Section 3/4.4 7 of the-Byron Technical Specifications.

These limits are 100 ppb.

dissolved oxygen when the temperature is greater than 250*F-and 150 ppb for Fluoride-and Chloride at all-temperatures.

A detailed discussion of Stress Corrosion-Cracking Susceptibility is provided in the Westinghouse Fracture Mechanics Evaluation MMTD-SMT-062 Section 3.4 which is attached to this report.

8)

CONCLUSION-All the ultrasonic examination-indications detected on the nozzle to vessel welds toJthe 2A and 2B RHR heat exchangers tube side nozzles have been found to.be acceptable in accordance with:ASME Section XI IWB-3500-or IWB-3600 as-applicable.- Therefore,-with the prior NRC approval of-the-Byron /Braidwood evaluation methodology and guidance from NRC-Generic Letter 91-18, system operability was not impacted.

Those flaws which have been-determined to be acceptable by-the Fracture Mechanics Analysis will be monitor 3d in future Byron Unit 2 Refueling Outages as required by ASME Section XI IWC-2420..

The ultrasonic examination indications noted are consistent with those noted at Braidwood' Unit 2 and are consistent with' fabrication flaws rather than service induced--flaws.

These indications are-acceptable-for continued service without-repair as defined in the Westinghouse: Analysis.

~.

4 Y

~ ATTACHMENT A INDICATION

SUMMARY

Component: 2RH02AA Wald Not' 2RHXN-2 Inlet Nossle A total.of 15 indications above 50% DAC were recorded with 13 of these indications exceeding 100% DAC with definable length.

The following is a. summary of indications which exceed 100%

DAC and exhibit a definable depth and length as reported in Ebasco ultrasonic report number 92BY2-UT-125:

Ind.

Loo.

Max. Amo.

- Lath.

,a (2a)**

a/l a/t 3

7.2-7.8" 200%

0.6"

(.109) 091 13.6 5

8-10.5" 400%

2.5"

(.078) 0156 9.75 6

10-10.75" 251%

0.75"

.187 249 46.75

=

7 11-11.25" 158%

0.25"

(.094) 188 11.75-8 12.6-12.7" 251%-

0.10"

(.094) 47 11.75 9

12.8-14.5" 447%

1.70"

(.125) 037 15,75-14 24.8-26" 282%

1.20"

.109 091 27.25-16 27.5-28.3" 251%

0.8"

(.094) 058 11.75 17 31.8-33" 224%-

1.2".

( '. 05 6 )

023

-7.0 19 35-35.7" 200%-

0. 7 "'

-.125 178 31.25--

20 37.3-37.7" 224%

0.4"

.125 3125 - 31.~25 21 38.6-41" 562%

' 2.4"

.0155

.064 3.8.

a/t represents through wall percentages of' indication-utilizing the nozzle wall thickness (.400'!).

• • Denotes ASME Section XI -

characterizationL(i.e. a=(Article.IWA-3000).

surface, 2a= subsurface).

l l

4, e-w.-

,- e y-

,e,,---

,,.y.e,4,,, - -:,-

+

r-

,,,-,,.--~.~m.,...,.~.w.....v--..

c,,,-

,.,.--,,.,,,,g

I s'

ATTACHMENT A Components: 2RH02AA Wald No 2RHXN Inlet Nossle CECO SKAD UT LEVEL III EVALUATION:

Ebasco-Indication Maximum-Thru Wall Ind. Not -

Location Lo t h. -

Deoth Decth 01 3.2-6.2" 3.0"

.250" 38%

Note: The-percentage of thru-wall depth was calculated utilizing the nozzle thickness 1(.400") and fillet-weld reinforcement thickness (.250") at the indication-location.

These indications exceed ASME.Section XI Article IWB-3500 acceptance standards.

All flaws were found to be not open to the surface by ultrasonics.

9 l

l' ATTACHMENT A i

INDICATION

SUMMARY

Component: 2RH02AA Wald Not 2RHXN Outlet Nossle-A total of 11 indications above 50% DAC were recorded with 10 of these indications exceeding 100% DAC with definable length.

The following is a summary of indications-which exceed 100%

DAC and exhibit a definable depth and length as reportedLin Ebasco ultrasonic report number 92BY2-UT-125:

Ind.

Lagt Max. Amo.

Lath, a(2a) all a/t 03-6-9.5" 400%

3.5"

(.063)

.009 7.87 04 11-12" 282%

1.0"

.156-

.156 39 05 12.5-14" 282%:

1.5"

(.125)

.041 15.63 06 14-16" 158%

2.0"

(.063)

.016-7.87 08-17.25-19" 158%

1.75"

(.063)

.018 7.87 09 21-22.25" 126%

1.25"

(.031)

.012 3.87 15 35-35.25" 224%

.25"

(.094)

.188 11.75 17 38-40" 400%

2.00"

(.078)

.019 S.75

• a/t represents through wall percentages of indication utilizing the-nozzle wall thickness (.400").

1

• • Denotes ASME Section XI (Article IWA-3000)

-characterization (i.e. a= surface, 2a= subsurface).

CECOLSMAD UT LEVEL III EVALUATION:

Ebasco Indication ~

Lath.

Death-Deoth Maximum-Thru Wall Ind. No.

Location 10 24.5-28" 3.5"

.223" 37%-

Note: The percentage of thru-wall-depth was-calculated utilizing the nozzle-thickness (.400")_ and_ fillet weld-reinforcement thickness (.200")-at-the indication location.

This indication was found to be connected ot the I.D.

surface.

s

+

ATTACHMENT A INDICATION

SUMMARY

Component: 2RH02AB Wald No 2RHKN-2 Inlet Nossle-A total of 8 indications above 50% DAC were recorded with 6 of-these indications-exceeding 100%-DAC with definable length.

The following isLa-summary of flaws-which exceed 100% DAC and exhibit a definable depth and length as reported in Ebasco ultrasonic report: numbers 92BY2-UT-060'and 061.

Ind.

Loc.

Max.-Amo.

Loth, a (2a) **-

AL1-a/t-11-13 10-13" 251%

3.00"'

(.144)

.023 17.75-30 35-36"

._12%

1.00"

_(.094)

.047 11.75L 31 36-37" 158%

0.50"

(.109)

.0545: 13.62 32 37-38" 251%

1.00"

- (.12 5 ) -

.0625

-15.62 These-indications exceed ASME-Section XI Article IWB-3500 acceptance-standards.

• a/t represents through wall percentages ofDindication utilizing the~ nozzle wall thickness (.400").

• • Denotes'ASME Section XI-(Article IWA-3000)-

(

characterization (i.e. a= surface,.2a=cubsurface).

All flaws were found to be not open to the surface by ultrasonics.

l l-I 1^

V

't

=

+<-M rp m

Ap W

>e-ww-V-

• l*f at

• 9 4

N' W'

T*"

\\*

ATTACHMENT A INDICATIr

SUMMARY

Component: 2RH02AB' Wald No 2RHXN-1 Outlet.Nossle-A total of 38 indications above 50% DAC were recorded with 20' of these indications exceeding 100% DAC with definable length.

The followingJis a-summary of indications which exceed 100%

DAC and exhibit a definable depth and length as reported in Ebasco ultrasonic report number 92BY2-UT-112 and 113:

Ind.

Loc.

Max. Amo.

Lath, a(2al**

a/1 a/t' 02 1-2"

-125%

.5"

(.078)

.078 "9. 7 5 -

a03 2-3" 125%

.5"

(;078)

.078 9.75-04 3-4" 125%

.5"

(.140)-

.140 14.0 06 5-6" 200%

.5"

-(.140)

.140 17.5 07 6-7" 178%

.75"

(.062)

-.041 7.75 10 9-10" 125%

.5"

(.093)

.093 11.63 11 10-11" 200%

.5"

(.078)

.078 9.75-16 16-17" 316%

1.0"

( 062)

.031 7.75-29 31-32"'

141%

1.0"

(.093)

.'0465 11.63L

-30 32-33" 124%.

.5"

-(.093)

.093 11.63 31-33 33-36" -

224%

3.0"

(.093)J

'0465 11.63 35 37-38" 159%

1.0"

(.062)-

- 031

.7.75 36 38-35" 447%

.75"

(.078)

.052 9.75_-

l 40 42-43" 125i 1.0"

.156

.156 39.0 a/t represents through wall percentages of indication utilizing the nozzle wall thickness (.400").

• • Denotes ASME Section XI (Article IWA-3000) characterization-(i;e. a= surface, 2a= subsurface).

.,.. ~,.

-.. _. ~. - -..

t ATTACHMENT A' Components-2RH02AB.

Wald Not 2RHXN-1 Outlet Nossle CECO SMAD UT LEVEL III EVALUATION:-.

Ebasco Indication Maximum Thru Wall Ind. No.

Location Loth.

Deoth Deoth 25-28 25-30" 5.0"

.341" 52.5%

Note: The percentage of thru-wall depth was calculated utilizing the nozzle thickness (.400") and fillet weld reinforce 1aent thickness (.250") at the indication location..

These indications exceed ASME Section XI Article IWB-3500 acceptance standards.

Note:

All flaws were found to be not open to~the surface by ultrasonics.

l

.~.....

PIGURE 1 l8 I

I lU. i, n Ii l,i l '#

s l I

l-I o

Ii)

I J j,I p,!flo 1 lijq.

I E

n,i s

f f,.

4-pl s AN'

?

p it,I

((

i i

1.,

s h

kl I

i ll yp-7 !

!!.fi is;,$'l$!"'.

if i

3 r

s:

y s_

s n ; L) v.!.. p i

l

. \\[ 3f $6*.',,

• 4.

~

f.: y

. y

/ y, -

s 11 glf gR,Wl l y\\s..!e N

.1 5

i s

1. Olp Si e

h g

(j =t {I

'll 3

i 1,,8!::1 6

i l {l 4

' ?

pp

/

2

_ v, y.

.,[ i m

5 s

~~"

,i ils la o

+

t w 1

8

• • pcsm-

1. r-

• r,,,,,-

W : WW le' 1

3!:

-jf,$'Cp.N'. i G

ps\\oQ l

. ns.

se.

u3

@. [. I v,,^ s:#,;{.. '

l: ') w' ;/,

/

, ff

• p ):

f, m

,wd e

,3..r-

, I/ g5

'i,,,,..'

pp..

g j

g

.g Pi.1iei 3,

il 1 1

!;r:s I

3

, _ _ ):

i b;

l

~.-

,5 e

i

~.

a.

_c

--,_____.._,_._.._.i.

,;b l'

I p t.

s. y' 4.

i(!f i

I

~

.{

i e

e

• hD 44 i

.A-

PIGURE 2 wir i ao wir :

W T~

IMOT TO SCALE) l VESSEL WALL T*0.875

/

N0ZZLE

/

(TYR)

N.0.376 b\\\\\\\\\\\\

RElHFORCEMENT PAD W

• l.25 (SEE DETAll A)

I/4 a 45' CHAMFER TYRi 4) CORNERS

- 23*-

l i

i DIMENSIONS SHOWN ARE NOMINAL 2 0'- --

% SHELL AXIS

-as DETAll A - REINE PAD

RESIDUAL HEAT REMOVAL HEAT EXCHANGER TUBE SIDE NOZZLES FLAW EVALUATION CHART BYRON UNIT 2 2A INLET NOZZLE O. 7 __

i i

i

0. 6_

L N

u

'N' L_

's 0.5 -

/a i N

n

/W 3

/_

T O. 4._

M

/

=

o CJ

_/

M l

t1 d FLAW DEPTH a/t u

i in

• -~

0.3 _

A T

/

v.

g i

rs a

W) 0.2 _ (N

' /

-m 8

M

/

t w )

7

~

p

,s g2

+

\\

- vw 0.1 _

n s a r i

i X

x-es

( 71) A!77 Idl I

O_

'4

• 1 Y

i I

I I

I I

i i

l i

i I

O 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 FLAW IDEd/CIRCUhttsNCE A

8Mtt

• 5 i

S

,iI iI%

0 EL 0

u

.N Z

5 Z

4 i

0 N

A' E

ii w

i14 4

t D

T f

i I

u 0

S 2

u

)

E T

I 5

B N

s 3

(

U U

0 E

i T

i

!i CN E

F E

E O

R 3

E G

R E

i L

N Y

Z

).

0 F

M A

B Z

U O

C H

N 5

t C

T 2

uU X

R T

0

/

Il i

E E

A L

H H

T T

T U

G A

C O

2 N

E E

i H

N A

I iI 0

L O

2 W

I L

T 5

AL A

A 1

F V

U 0

I O

L M

A sT s E

V

-C

+

)

R E

5 r y'

0

.9 '

I4 I 1

/

I T

V

.0 ^

V A

A s7;W

(

-t E

L s'

/

7, u l

l s 5 o'

5 H

F

/

/

e.

4 I 0

-m?

K'

/

A b

0 L

b)~

N I

^

i U

iY ss Q'

D

-u r

$!t*

f I

I O

S ER 7

6 5

4 3

2 1

O t

/a O 0

O 0

0 0

O H

TPE WA LF

RESIDUAL HEAT REMOVAL HEAT EXCHANGER TUBE ElDE N0ZZLES FLAW EVALUATION CHART BYRON UNIT 2 2B INLET NOZZLE 0.7 _

i 0.6 -

' s M9

^%m, 0.5 _

w'N i

m 0.4 _

N Q E

-~

c:

w w

FLAW DEPTH a/t, D'

O.3 _

~

( B )

F

( 4 )

)

ih 851 0.2 _

1 i

H

&A

/

l

/

/

A7

/

/

/ /

es J9 0 j jf./

f

~~'

spo) a y/'

/

7 0.1 _

/

r

%:-w f 5 2

x

1. 3e N 7 >

71 R

O_

tv i

v

~

't 11 1

I I

I I

I I

I I

I I

O 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 FLAW LENGTH /CIRCUMFEPENCE

RESIDUAL HEAT REMOVAL HEAT EXCHANGER TUBE SIDE N0ZZLES o

FLAW EVALUATION CHART BYRON UNIT 2 2B INLET NOZZLE 0.7 __

0.6 _

' s'N 0.5 _

j'

-g

~

n E

O.4 _

g ra FLAW DEPTH a/t.

O.3 _

f1 il 0.2 _

ah

.~'

V 3 3

/

1, y-l

/

s,

-JU 0.1 __

~~

~

O_

i l

i i

i i

l i

l i

1 0

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 FLAW LENGTH / CIRCUMFERENCE

ATTACHMENT D FRACTURE MECHANICS EVALUATION i

l 1

l l

ZNLD/1786/5

.i MMDT-SMT-062(92)

FRACTURE MECHANICS EVALUATION i

BYRON AND BRAIDWOOD UNITS 1 AND 2 RESIDUAL HEAT EXCHANGER TUBE SIDE INLET AND OUTLET N0ZZLES i

t 6

i March 1992:

f W. H. Bamford H. Jambusaria Y. S. Lee i

WESTINGHNJSE ELECTRIC CDRPORATION Nuclear and Advanced Technology. Division' P.O. Box 2728 Pittsburgh,: Pennsylvania 15230-2728

• 1992 Westinghouse Electric. Corp.-

i i

l'

+

p Y

r

..._...---._......__._,-__-s.---....~.--_-.._.~<-...._.-.-.~.,-

,, _ _ - _ _. ~,.....,,. _

.. - ~.

4*

4 i

I TABLE OF CONTENTS l

1.0 INTRODUCIIDE l

1.1 Code Acceptance Criteria 1.2 Geometry

)

2.0 LOMG CONDII]ONS. FRACTURE ANALYSIS METHODS; AND MATERIAL PROPERTIES 2.1 Transients 2.2. Stress Intensity Factor Calculations 2.3 Fracture Toughness 2.4 Thermal Aging 2.5 Allowable Flaw Size Calculation 3.0 SUBCRITICAL CRACK GROWTH i

3.1 Analysis Methodology 3.2 Crack Growth Rate Reference Curves 3.3 Residual Stresses 3.4 Stre.ts Corrosion Cracking Susceptibility 4.0

SUMMARY

AND RESULTS 4.1 Flaw Evaluation' Charts Construction 1

1 4.2 Conservatisms in the Flaw Evaluation 5.0.

REFERENCES-r l

~ WF1260J/032M2:10 1

s SECTION

1.0 INTRODUCTION

This fracture mechanics evaluattor, has been carried out to determine the largest size of indications which can be accepted according to the rules of Section XI, paragraph IWB 3600 for the residual hest exchanger inlet and outlet no:71es. The results of this evaluation aru presented in flaw evaluation charts in Section 4, and the technical basis for construction of the charts is contained in the remaining sections.

1.1 fade Acceotance Cetteria The evaluation procedurer, and acceptance criteria for indications in austenitic stainless piping are contained in paragraph 148 3640 of ASME SectionXI.[1] The evaluation procedure is applicable to all the materials within a specified distance from the weld centerline, vrt, where r the pipe nominal outside radius and t is the r.ominal wall thickness. For example, at the RHX nozzle, this distance is calculated to be 1.62 inches, which encompasses regions of the heat exchangt, as well as part of the RHR line.

All the materials in this region are Type 304 stainless steel.

The evaluation process begins with a flav growth analysis, with the requirement to consider growth due to both fatigue ar.d stress corrosion cracking.

For pressurized water reactors only fatinue c-ack growth need be considered, as discussed in section 3.

The methodology for the fatigue crack growth analysis is described in de,.all in section 3.

l l

The calculated raaximum flaw dimensions at the end of the evaluation period are l

l then compared with the maximum allowable flaw dimensions for both normal l

operating conditions and emergency and faulted conditions, to determine acceptability for continued service. Provisions are made for considering j

flaws projected both circumferential1y and axially.

I In IWB 3640 the allowable flaw sizes have been defined in the tables based on maintaining specified safety margins on the loads at failure. These margins are 2.77 for normel and upset conditions and 1.39 for emergency and faulted WPF1260J/032792:10 1

9 i

conditions. The calculated failure loads are different for the base metal and the flux welds, which have different fracture toughness values, as discussed in section 2.

The failure loads, and consequently the allowable flaw sizes, are larger for the base metal than for the welds. Allowable flaw sizes for welds are contained in separate tables, in !WB.3640.

1.2 Geometry The geometry of the residual heat exchanger is shown in Figure 1-1, with the details of the inlet and outlet nozzles of the_ tube side shown in Figure 1-2.

The notation used for surface flaws in this ieark is illustrated in figure 13.

The fracture and fatigue crack growth evaluations carried out to develop the handbook charts have employed the recommended procedures and material properties for stainless steel as prescribed in paragraph IWB 3640-and Appendix C of Section XI.

c l

WPF1260J/032792810

-.. - - -.. _ ~

i C'

%>\\

@g" *:;', Je..s.n, am

• ~ 4' aws.soss eos as c E'

u I

/. V

',; p#

i

~ ' * * *

• t use.o ose gw -

s. _ _ ' ! b_

o go e M8

(

e a' L b '46me sq..ocam ss t y yjg l

v e

.g' f8).ackeet 0 4 se # '

1 *. "#

Useinsvaaoom f isoa : ers c ro.

m ee g se aan a A s4 ANc64meoJS d OR 'UJ" 7'. 2 E G*f. I [as een p a.a Ag,3,A N g.....

• e.2 se,r.s1 4

e e # o wo.

ang$ 5 A 5.

[TDN N 5.

<n s

w

.. J Io o h

/

t.. -.s e

.. o......

g I['

)

m-t y

\\

.4 2

l r,

i i

i o

o b

e

. : -Q 4 SIDEVIEW i

4?

i

\\ *s,

=

5 g

A r?1' 9,d ' *.3 m

[ ',t.D w

• y L

'A?!p, 5I

., I

. s.o.

,x, 4 _

.y l

j e,

.h s'g e er,.,,,,

.aue et ses

• " ~ ** % rts v.nes i. <..oo-a ***

Fi9ure 1-1.

Geometry of the Residual Heat Exchanger WPFON3/111191:10 3

_._ _ _ _ a,_ _.,, :._

9 1

1 t

VESSE WALL 4

RElff0RCBM V

(

- O.@", actual wall' ct31_cgo,,,,

J h-131J \\%LL=.1" NH l

Figure 1-2.

Geometry ofithe-' Tube. Side Nozzles (Inlet.andOutletNozzle: areIdentical)'-

2 WPF0063/111291 10 4

e

.,4

.w__m_,

,-w

~n=....._.,y o,.'c...

Wall Thickness t e

i 2

I

%_L g

L ]

a l

-t Figure 1-3.

Typical Notation for Surface Flaw Indications wF0863/111191:10

SECTION 2.0 LOAD CONDITIONS, FRACTURE ANALYSIS HETHODS AND MATERIAL PROPERTIES The loading conditions used in the analyses described herein were taken directly from the equipment specification. The fracture analysis methods are the most advanced which are now available, and the material properties are the latest available properties contained in the ASME Code.

2.1 Transients and Load Conditions The design transients for the residual heat exchanger are very minimel, because this component operates only during plant shutdown conditions, Therefore the only transient conditions which it experiences are the startup and shutdown of the system, which coincides with the shutdown and startup of the plant, respectively. The appropriate limiting load conditions for the location of interest are discussed next.

The loading conditions which were evaluated include thermal expansion (normal and. upset), pressure, deadweight and seismic (OBE and SSE) loadings. The RHR piping forces and mnments for each condition were obtained from the ASME Code Section III calculations previously performed by Sargent and Lundy and Westinghouse for Byron and Braidwood Units 1 and 2-(2-5). Theseloads(6) were compared with the Equipment Specification design loadings for the heat exchanger nozzles (G 679150 Rev. 1) and found to be bounded by them. As a consequence of this comparison, the evaluation performed using the design loadings, is applicable to Byron and Braidwood Units 1 and 2.

Residual stresses were not used in this portion of the evaluation, in compliance with the Code guidelines. A further discussion of residual stresses is contained 1

in Section 3.2.

The stress intensity values were calculated using the following equations:

S I - P, + P3

+j[N'+N+#)'5) 8 SI =

WPF1260J/032792:10 6-

---

.v y-,yee-ww----y#4-

-r-,--,

y-.-w wy gp;<,-

w e-

.+r

++

-+v

<h rs-*-1-e.=wm y,--w

.-.w 1-wr vw,,.-

c.--v-vevy,-w--wy re--,

where F, = axial force component (membrane)

M,, M,, M, = moment cemponents (bending)

A = cross section area Z = section modulus

-The section properties A and Z at the weld location were determined based on the minimum pipe dimensions. This is conservative since the measured wall thickness at the weld is generally-larger.-

The following load combinations were used.

A.

Normal / Upset - Primary Stress Pressure + Deadweight + OBE B.

Emergency / Faulted Primary Stress Pressure t Deadweight + SSE C.

Normal / Upset - Total Stress Pressure + Deadweight + OBE + Normal Thermal D.

Emergency / Faulted Total Stress Pres.Jre + Deadweight + SSE + Normal Thermal T

2.2 Stress Intensity heter calculatto.01 One of. the key elements of the fatigue crack growth calculations-is the determination of the driving force or stress intensity-factor (K ). -This was-g done using expressions available from the literature.

In all cases the stress intensity factor calculations utilized a representation of the actual-stress profile rather than a linearization. This was necessary to provide-the most WPf1260J/0s2Mt:10 7

s accurate detennination possible. The stress profile was represented by a cubic pu1 nomial:

3 j + A,

+A (2-1) o(x) = A, + A3 3

where x

is the coordinate distance into the wall wall thickness t

stress perpendicular to the plane of the crack a

=

coefficients of the cubic fit A,

For the surface flaw with length six times its depth, the stress intensity factorexpressionof[McGowanandRaymund[7])a,c.e was used. The stress intensity factor Kg ($) can be calculated anywhere along the crack front. The point of maximum crack depth is represented by & = 0.

The following expression is used for calculating Kg ($), where d is the angular location around the crack.

'd.S (coa 4 +

sin 4)1/'(Ao o +

AH (2 2) 8 8

R K ($)

=

3 3 y

A,H, +

A,H,)

+

The magnification factors H ($), H ($), H,($) and H (c) are obtained by the o

3 3

procedure outlined in reference [8),

The stress intensity factor calculation for a semi-circular surface flaw, (aspect ratio 2:1) was carried out using the expressions developed by (Raju and Newman (8)).

Their expression utilizes the same cubic representation of the stress profile and gives precisely the same result as the expression of

[McGowan and Raymund]6'd for the 6:1 aspect ratio flaw, and the form of the equation is similar to that of (McGowan and Raymund)*d above.

WPF1260J/032792:10 8

w

The stress intensity factor expression used for a continuous surface flaw was thatdevelopedby(BuchaletandBamford(9))*****. Agair, the stress profile is represented as a cubic polynnmial, as shown above, and tnese coefficients as well as the magnification factors are combined in the expression for K, a, e,.

A Fs +

As F, +

a*A F (2-3)

I, = {ia Af +

1 3

where F, F, F, F are magnification factors, available in (9).

3 e

3 4

2.3 Fracture Touahness The residual heat exchanger is stainless steel type 304. The weld at the nozzle was made by the shielded metal arc process,-as verified by the shop traveller, and the weld procedure referenced therein.

The fracture toughness of the base metal has been found to be very high, even at operating temperatures (10), where the J, values have been found to be i

t well over 2000 in-lb/in.

Fracture toughness values for weld materials have been found to display much more scatter, with the lowest reported values significantly lower than the base metal toughness. Although the J, values i

reported have been lower, the slope of the J R. curve is still large for these J

cases. Representative values for J, were obtained from the results of ge i

Landes, et. al. [11), where'the following values were obtained, and used in the devek pment of the fracture evaluation methods:

3

[

for shielded metal arc welds: J, = 990 in 1b/in.)*'

i 2.4 THERMAL AGING l

Thermal aging at operating temperatures of reactor primary piping can reduce the fracture toughness of cast stainless steels _and..'to a-lesser degree, stainless steel weldments. -Because of the lower operating temperature (400'F) of the residual heat exchanger, and the fact that the materials are type 304 stainless (not cast), thermal aging in this component will be negligible, wnasovosamato

t e

2.5 Allowable Finw Size Determination l

The critical flaw size is not directly calculated as part of the flaw evaluation process for stainless stec15.

Instead, the failure mode and critical flaw size are incorporated directly into the flaw evaluation technical basis, and therefore into the tables of ' Allowable End of-Evaluation l

Period Flaw Depth to Thickness Ratio," which are contained in paragraph IWB 3640.

i Rapid, nonductile failure is possible for ferritic materials at low temperatures, but is not applicable to stainless steels, in stainless steel i

materials, the higher ductility leads to two possible modes of failure, plastic collapse or unstable ductile tearing. The second mechanism can occur when the applied J integral exceeds the J fracture toughness, and some gg stable tearing occurs prior to failure.

If this mode of failure is dominant, the load carrying canacity is less than that predicted by the plastic collapse mechanism.

The allowable flaw sizes of paragraph IWB 3640 for the high toughness base materials were determined bared on the rssumption that plastic collapse would be achieved and would be the dominant mode of failure.

[However, due to the reduced toughness of the shielded inetal arc welds. E is possible that crack extension and unstable ductile tearing could occur and be the dominant mode of failure. This consideration in effect reduces the allowable end of interval flaw sizes for flux welds relative to the austenitic wrought type 304 vessel and piping materials, and has been incorporated directly into the evaluation t abl e s. ]'d

i l

WPf1260J/032792:10 10

i SECTION 3.0 FATIGUE CRACK GROWTH In applying Code acceptance criteria as introduced in section 1, the final flaw size a7 is defined as the flaw size to which the dstected fle.w is calculated to grow at the end of a specified period, or until the next

- inspection time, This section will examine each of the calculations, and provice the methodology used as well as the assumptions.

3.1 Analysis Methodoloav The metnods used in the crack growth analysis reported here are tne same as.

those suggested by Section XI of the ASME Code. The analysis procedure involves postulating an initial flaw at specific regions and predicting the growth of that flaw due to an imposed series of loading transients. The input required for a fatigue crack growth analysis is basically the information which depends on crack and structure necessary to calculate the parameter AKg geometry and the range of applied stresses in the area where the crack exists.

Once AK is calculated, the growth due to that particular stress cycle can be g

calculated by equations given in section 2.2 and figure 3-1.

This increment of growth is then added to the original crack size, and the analysis proceeds to the next transient. The procedure is continued it this manner until all the transients known to occur in the pirriod of evaluation have been analyzed.

l The only transients considered in the analysis were the startup_and shutdown of the RHR system. These transients are spread equally over the design

~

lifetime of the vessel.

Crack growth calculations were carried out for a range of flaw depths, and three basic types. The first two were surface flaws, one with length equal to e

six times the depth and.another with length equal twice the depth. Third was i

a continuous surface flaw, which represents a worst case for surface flaws.

WF1260J/Os2792:10 11

c-3.2 Crack Growth Rate Reference Curves The reference crack growth law used for the stainless steel was taken from that developed by the Metal Properties Council Pressure Vessel Research Comittee Task Force in Crack Propagation Technology.

The reference curve has the equation:

A"- = CFS b Ka (3~7) x where A8 - crack growth rate, inches per cycle material coefficient (C = 2.0 x 10*I9)

C F

frequency coefficient for loadings (F = 2.0) 2

.0 S

Rratiocorrectioncoefficicnt(S= 1.0 0.502 R )

=

material property slope (=3.0321) n AK stress intensity factor range, psi /in

=

This equation appears in Section XI, Appendix C (1989 Addendum) for air environments and its basis is provided in reference [12), and shown in figure 3 1.

For water environments, an environmental factor of 2 was used, based on the crack growth tests in PWR environments reported by Bamford [13].

3.3 Residual Stresses Since the residual heat exchanger vessel-to-piping welds were not stress relieved, residual stresses are clearly present.

For fatig'se crack growth analyses, these stresces were included directly, in general the distribution of residual stresses is strongly dependent on the degree of constraint of the structure. The stiffer the structure the higher the residual stresses. For a thin walled large diameter pipe the residual stresses will be lower than a small diameter thick walled pipe. This has been found by a number of investigators and there is general agreement that the distribution of residual stresses is tensile near the surface, and then wa126onoszm:10 1

12

]

e

\\

compressive near the center of the wall after which it reverses to become tensile at the outer surface.

The residual stresses were taken from work reported by General Electric (14) and E. Rybicki (15), which included both measurements of residual stress and finite element calculations.

Both approaches were found to be in agreement, and included a range of pipe sizes from 4 inches to 28 inches in diameter.

The stresses were found to peak at the weld, as shown in Figure 3-2 for a 10 inch diameter pipe.

the through wall distribution of residual stresses used in this analysis was taken from the work of Rybicki, and is shown in Figure 3 3.

This distribution is for a 10 inch schedule 160 pipe with a thickness of 1.125 inches, which is a much stiffer configuration than the 14 inch diameter, 0.375 inct ; hick junction at the heat exchanger nozzle.

3.4 ftress Corrosion Crackina Susceotibility In evaluating flaws, all mechanisms of subcritical crack growth must be evaluated to ensure that proper safety margins are maintained during service.

Stress corrosion cracking has been observed to occur in stainless steel in operating BWR piping systems. The discussion presented here is the technical basis for not considering this mechanism in the present analysis.

The residual heat exchanger tube side nozzles are exposed to only primary coolant Water.

For all Westinghouse plants, there is no history of cracking failure in the resctor co91 ant system loop piping.

For stress corrosion cracking (SCC) to occur in piping, the following three conditions must exist simultaneously:

high tensile stresses, a susceptible material, and a corrosive environment.

Since some residual stresses and some degree of material susceptibility exist in any stainless steel piping, the potential for stress corrosion is minimized by Wer saintion of a material immune to SCC as well as preventing the

& r uce of a corrosive environment. The material specifications consider s hility with the system's operating environment (both internal.and eu2 nal) as well as other materials in the system, app'f cable ASME Code rules, fracture toughness, welding, fabrication, and processing.

WF126cJrD32W6 13

e e

'a

• Unser enwrps4 twines recom.

[

[

M

~

menesse to eseownt for toe 6e esponsense of emer eentenevent

/

8 (g*?

/

ownes, for 0.25 <A < 0 Al fer 000 4

.es.

e.o:

.$ = (121 X 10) 0 A #1B$

~

l 2

,9 &

m

[

E'

[/

0 = 3.78 A

• ODS 2

e

1. = K,,,,n it,nes f/g &

~

m

/

,4 *e.,-

/

leir enarenenenti 100 4

3

.$. e 10D267 x 10 ) A Kg.726

)

k.

~

}

70

/

h

~

1-Dewemene new AK et wheeh the

/

A,e

_ _,.en e,

/

.n e_ _,

e I,

• /t,4 evn i.

j rt

/

isionetresetor enwrenmenti 30 espoeemefor A < 025 f

• 025 < A < 0.85 f

1. > 026 10 A e g,,,, fgm

/

N l

7 I

9 p

'Unser enerpe6etion 6e seenmenenced g

,f (

p to esseunt for A rette essendense

..ee...., -, _...e, g_

l 0.26 < # < 0.06 for eseos siese:

f C

d'.

• 11.02 X 10 ) Og Ag5.96 4

e m

I l

I/I Og* 2634 5.726 A e K,n (Kme, m

I.

i l

i I I I I lil l

l l l l1Il 1

2 8

7 10 30 to 70 100 Seren inteneN Fector Menge (AKg hai.@,)

Figure 3-1.

Reference Crack Growth Rate Curves for Stainless Steel in Air Environments [12].

WPF1260J/032792:10 14

. =. - _ _

s n'W 1

EYI 1

j e!%

i

,1%

i tiet piles seo.1 PitCI 8*0. I l

1,03 i-1 1

l(,

i l

f I

I I

! 'i's 1

l g

. g I

ti

.4%

V, I

~

I I

-6%

I l I

I\\

o, pi

-a u l

-317.'c-azi.

4-toi i

e i

'I'#

O!?d di.d d%*d o'%*A 0'.*d ITAL' Figure 3-2.

Maximum Principal Surface Residual Stress for a 10 inch Schedule 160 Pipe [14)

WPF1260.'/032792:10 15

I l

10' ScatDuLt 440 *tPt LOC 4780s: 019' F#0m wtLD CtwfImLiest

'/

/

/

j p

__;saln sm..,,eg,, 11 J

l

~..

W

/

I

/

I f,A g

/

I g

(

,,i... ;;,'au I

13 sumuur T z.

,g w

i

.a -

.n. s ps-s

\\

\\\\,

to

• .0

• 8o 0

30 40 to assiouat. :Tassa, w l

Figure 3-3.

Through Wall Distribution of Residual Stress in a 10 Inch, Schedule 160 Pipe,inaCrossSectionAdjacenttotheWeldCenterLine(15) wF1260J/032M2:10 16

e SECTION 4.0 4.1 riaw Evaluation Charts Construction The acceptance criteria for surface flaws have been presented in Section 1.

For flaw evaluation in stainless steels, only the fatigue crack growth results must be calculated. The allowable flaw depths were determined directly from the tables in IWB 3640.

The first set of data required for surface flaw chart construction is the final flaw size a,.

As defined in IWB-3611 of ASME Code Section XI, a, is the flaw depth resulting from growth during a specific time period, which can be the next scheduled inspection of the component, or until the end of design lifetime. Therefore, the final depth, a, after a specific service period of tirne must be used as the basis for evaluation.

The final flaw size a, can be calculated by fatigue crack growth analysis, which has been performed covering a range of postulated flaw sizes, and flaw shapes. The crack growth calculational methods have been discussed in Section 3.

The results of the crack growth calculation showed that growth for a complete range of crack sizes, up to 60 percent of the wall thickness was inconsequential for the entire service life of 40 years. This was expected.

since the region sees so few cycles.

The allowable flaw size for stainless steel is obtained directly from tables in paragraph IWB 3640, so the evaluation process is very straight forward.

The allowable flaw size is calculated based on the most limiting transient for ar, normal operating conditions. Similarly, the allowable flaw size for emergency and faulted conditions is determined. The theory and methodalogy for the calculation of the allowable flaw sizes bn been provided in Section 2 and Reference 16. Allowable flaw sizes were wculated for a range of flaw shapes.

The two basic dimensionless parameters, which can fully address the characteristics of surface flaw, have been used for the evaluation chart construction. Namely, WPF1260J/032792 10

[

17 1

o Flaw Length divided by the circumference, t/c o

Flaw Depth parameter a/t

where, wall thickness, in.

t flaw depth, in.

a

=

flaw length, in.

t pipe circumference, in.

c

=

The flaw evaluation chart for the residual heat exchanger inlet and outlet nozzler is shown in Figure 4 l.

The chart has the following characteristics:

o The flaw length / circumference t/c was plotted as the abscissa from 0 to.5.

Fo. values of t/c which exceed 0.5, use the res91ts for t/c

= 0.5.

o The flaw depth parameter a/t was plotted as the ordinate.

o The upper boundary curve shows the maximum acceptable flaw depth based on flaw evaluation, beyond which no surface fir' is acceptable for continued service without repair.

This upper

.id curve has been determined by the frccture and fatigue evalua w s described herein, using Tables IWB 36415 and IWB 3641-6, for shielded metal arc welds, o

Any surface indication which falls below the boui.dary curve will be acceptable by the code rules, based on the analytical justification provided herein. However, IWB 2420 of ASME Section XI requires future monitoring of such indications.

A detailed example on the use of the charts for a surface flaw is presented l'elow:

WPF1260#032792:10 18

.' s i

?

I f

Surface Flaw Examole Now suppose an indication is to be evaluated using sne charts, for the l

circumferential rientation:

a = 0.10' t = 6.1" t = 0.40' c = 44.0' i

The flaw characterization parameters then becomes a/t = 0.250 t/c = 0.139 Plotting these parameters on the surface-flaw evaluation chart of Figure 4-1, it is quickly seen that the indication is acceptable.

4.2 Conservatisms in the Flaw Evaluation The stress and fracture analysis results presented herein have been structured to be conservative at each step, to ensure that the final result will be conservatS's.

The stresses applied to the heat exchanger nozzles were taken.froin the vessel equipment specification loads, which represent bounding loads for the structure. The actual loads for the Byron and Braidwood Units 1 and 2 heat exchangers(6)iceabout60percentofthedesignloads.-

i The residual stresses used in the analysis vere taken from a combination of measurements and analysis for a 10 inch schedule 160 pipe. The smaller pipe diameter and larger thickness (1.125 inches) for this pipe mean that the residual stress distribution used here will be very conservative relative to the heat exchanger nozzle.

Since the publication-of the flaw evaluation criteria and methodology for stainless steel (16) a number of experiments have been carried out on large i

fracture toughness specimens and full size pipes with both submerged arc welds WPf12MJ/WWFN:10 19 a,

~

and shielded metal art welds [17). These experiments have shown that the fracture toughness from these larger specimens is higher than the toughness values used in the development of the flaw evaluation methods. Therefore the flaw evaluation results presented here are conservative.

A further conservatism is added to this fracture evaluation by using the fracture criteria for a class 1 piping system for a class 2 component. There are presently no flaw evaluation criteria for class 2 components, but presumably if they were to be developed, smaller margins could be justified, with resulting larger allowable flaw sizes.

The indication depths from the inspections have been compared with the thickness of the pipe, with no benefit taken of the additional thickness resulting from the large fillet weld on the ot ' side surface of the nozzle. As shown in Figure 1-2, this fillet weld is immediately above the indications, and so the actual percentage flaw penetration is smaller than that reported, l

l-WPF1260J/032792:10 l

20 l

~.. -

. -. - ~

..n.-,.

4 e

0 e

u i

I i

(

I l

l

.........................................................-.........-...-....,:*...........m:...'....m....

kbbb b5ib.5b bi bbb 5b5 b 5 55 ?Nb55 E

b..

5bb 5b 5 55b b -

!bkhbihik khk! k!!h h!!khbkb!!kkkhbf! b[kkhbbbb!!!!h!bbib'bkhb! h!bhbb kbbbbb h h kbkb 8 hbhbkh! bi

': l'bh.ih !h!

k

m:m:m:mm :n:mn m:rm ::mm: mmmmn:=m:- rmum:m m:. - : :m::

m =:=

nimm nm r m:= r:m: :m mm-m+:in :m-m -

nx = m = =:dn

m:n ::mm :::m. mnm:

- :r m m :: : :: ::4 nr'm.r':... :, - :. : : n. :. : : tm n.

m::m :.n n:. m : n. : : m:m :::. :. :. :: n: :. : ::.:: :. :: :.:::: :. -' r.

1:-

. - : ::: m m m:-

l m-m: n :::.: :: m:

.:m :....:: mm m ; n ::: n ::.: n :r : nr.

- - - :. n.. - m:: m:::m:

I e

. E E:iiL.FE!:!!

EEE MEE EEil:E::iH EiiE EEE' inE:EEEEEE: EE ifik! ! i '!.i f f f 'f$h!

.k:!h! !'

':k b

^:

!!f h i;f bb:. !b

. m r :- : n m: m. n nn:m m m m : :n::.: um:m :nm - : ::mn :: =: : mum: :n.nr:r-n-

~~*'-":: ::'"'::':'.':'.'~:'::: '"'::':.. ': : ' : : ' : " ' ' ' ~ : ':~. '^' '^':: I': ' * * : x

• I:n bf!((!i 5$i!.)!. :.. '..

. f bb i : )

' bi nmm:

...=.m-.:m

...;..:.n..:

n.n::.: :.m:m. n.m m mm...

J.

!. [ hk! !!)ibibbb.i! b

.. : n. m m m.m m:m m::

. 4 0 ! 5.. 1.. S...... M. i.... 2....,. l. f....i.. i...... M... i...!. f.. 5..... L. "... _.... i. 5.f.,. i. 5...!. M i f...

4

.3

.a 7

...... : :.'.i... ':: ::... ::.. :. :;::.. ::::::::.. : 7 :: " : : :..J.. : ::...:......... ::..:.: ' ' ::::::::::::

kihihb. : :.';..f:b:::..'.:..'

hk. j f k ::bi bbb:ii h ! i h.

(.

^h. :f f

f..:.. f:f f ikki.kiiikk 2

!!!Ui? RV H L Ei ?. RTnilHE !!!!iii"!DUni!G:EE

==== =. J: 149 ; :hniii!!!!!

=

==m m

. = = = = :=

= = =

).30 =EEME iEE EEn'. 'L:E LE E :EEh! +EEE:iEiEE.EiE.i : H EEEEEEiiE Z

EiiE Ei:E E:E.... - - -....... -.....-...-....-........:......

.........=m.n EEE. EEEEEE EEEE:EEEEEE E EE-EEiEEE h

!!!!!!!!! $!!Lh NnNH [il:d!5!i:h5!!![!!$lill:f!D!S!i d!Q5!!5!!!!!

a iEEE :iz.E EEmr EmEEE EEi ErEEm::: m : EEEE sk:h!E i

IEEiEi:EE !E!EE EEE.!!EEEi E.i!E.iiiEi.i E E:E EEE. :E:E E.iE E!EEElli k.20 E E wE E E:e E EE:!!

"R ih H

• 1. 5E

=

EEE E Ei.iEEE EEE EEiE n E E E EEEE

.a u,

=:m: m m = r.:... := = n m:= m u m:. :.: m:.: m.mm.:==......:.:....m..mmm.n=

!!!!!!!E n!!! hie!!!Jii!n!!!!!Uili!!!!!!hij!!!!!!!ili!!!!!E!l!!!!!!i!!!!!ilii.!E. DEinE!!.!!!!!!!!!!!

gEEEE ErmEEEjEE:iEE=EEEEEinEEEEE EEE.EEEis v ::E iEE E E ii:iEEEEEi!E.EEEEEEiEE EEE:aEEEEmE A.E=i iE R

.10 -

iiE E EEEE!E!EEEiEii:iEiEEEEis EiiEi EliEliiEEEEiii:i2 I

m.g

..g

.= 3 m.

iE E !E E E E E i E ' E iE E : iiii!N !!... =....... =.. =......=........=..... =........ n : m m.

=m m m =:: ::iEr m=m::n-M i

m = m m = ns:=la m!4Ei E!!Ei E E E !E i. :! E E E E E M EiE EE

. +. - - - - -

n:= = = r n :.4:

idhdiiEEEiE iEiii!Eh!!!jiEdi -- j!itiiiE!i!Nih i!""mdjEEiEiiii liEhiihidiidi!idh EEE EEE E E~E EE:iiiH:-

EiEEEEEEEE2EEEE'

iiiiiiiiiiiiiiiiiiiiEEiE

Ei!!!EiEEiiiiEiiiiiiiiiiEiiE i"siEEEEEiiiEEEEEEEEEEEEEEEE O

O 0.1 0.2

. 0.3 0.4 0.5 FLAW LEEGTH / CD.CUMFERENCE Figure 4-1 Flaw Evaluation Chart for Byron and-Braidwood Units 1 and 2 Residual Heat Exchanger Tube Side Nozzles WPF1260J/032792:10 21

,.e 0

SECTION

5.0 REFERENCES

1.

>SME Code section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," 1983 edition (used for updated code allowable limits); 1983 edition, Winter 1985 Addendum (used for flaw evaluation of austenitic stainless steel piping); 1989 edition (used for reference crack growth curve, stainless steel).

2.

Jamtusaria, H., " Residual Heat Exchangers: Braidwood Unit 2,"

Westinghouse Report No. 031804 Rev. O, Jan. 24. 1986.

3.

Jambusaria, H., " Residual Heat Exchangers:

Byron Unit 1," Westinghouse Report No. 031805 Rev. O, 2/27/92.

4.

Jambusaria, H., " Residual Heat Exchangers:

Byron Unit 2," Westinghouse Report No. 031806 Rev. O, 2/27/92.

5.

Jambusaria, H., " Residual Heat Exchangers:

Braidwood Unit 1,"

Westinghouse Report No. 031803 Rev. O, 2/27/92.

6.

Letter 8 BPM #1577 from D. J. Skoza of Commonwealth Edison Company to Janet ca.1ecicky of Westinghouse Electric Corporation,

Subject:

RHR Heat Exchanger Nozzle Loads, dated 2/12/92.

l l

7.

McGowan, J. J. and Raymund, M., " Stress Intensity Factor Solutions for Internal Longitudinal Semi-elliptic Surface Flaw in a cylinder Under Arbitrary Loading", ASTM STP 677, 1979, pp. 365-380, 8.

Newman, J. C. Jr. and Raju, I. S., " Stress Intensity Factors for Internal Surface Cracks in Cylind-fcal Pressure Vessels", 6JME Trans.,

Journal of Pressure Vessel Technology, Vol. 102, 1980, pp. 342-346.

9.

Buchalet, C. 8, and Bamford, W. H., " Stress Intensity Factor Solutions for Continuous Surface Flaws in Reactor Pressure Vessels", in thtchanics of Crack Growth, ASTH, STP 510, 1976, pp. 385-402.

WPF1260J/032772:10 22

10.

Bamford,-W.-H. and Bush, A.

J.,

" Fracture of Stainless Steel," in Elastic Plastic Frac!stg, ASTM STP 668, 1979.

11.

Landes, J. D., and Norris, D. M., "Fract'ure Toughness of Stainless Steel Piping Weldments," presented at ASME Pressure Vessel Conference, 1984.

12.

James, L. A., and Jones, D. P., " Fatigue Crack growth Correlations for Austenttic Stainless Steel in Air," in Predictive Canabilities in Environmentally Assisted Crackina," ASME publication PVP-99, Dec.1985.

13.

Bamford, W.. H., " Fatigue Crack Growth of Stkinless Steel Piping in a Pressurized Water Reactor Environment," Trans ASME, Journal of Pressure Vessel technology, Feb.1979.

14.

" Studies on AISI Types 304, 304L, and 347 Stainless Steels for BWR Application, April-June 1975," General Electric Report NED0-20985-1, September 1975.

15.

Rybicki, E. F., McGuire, P. A., Merrick, E., and West, J., "The Effect-of Pipe Wall Thickness on Residual Stresses Due to Girth Welds," Trans ASfig, Journal of Pressure Vessel Technology, Vol 104, August 1982.

16.

" Evaluation of Flaws in Austenitic Steel Piping," Trans ASME,. Journal of Pressure Vessel Technology, kol.108, Aug.1986, pp. 352-366.

17.

Wilkowski, G. et. al., " Analysis of Experiments on Stainless Steel Flux i

Welds," Battelle Columbus labs report for USNRC, number NUREG/CR 4878, April 1987.

I t

WPF1260J/032792:10 23

~,.. _.

..,, _.