ML061800263

Crack Growth Rates in a PWR Environment of Nickel-Base Alloys from Davis-Besse and V. C. Summer Plants

ML061800263
Person / Time
Site:	Davis Besse, Summer
Issue date:	09/18/2006
From:	Alexandreanu B, Chopra O, Cullen W, Shack W Argonne National Lab (ANL), NRC/RES/DFERR
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ML061810190	List: ML061800263 ML061810182
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Crack growth rates in a PWR environment of nickel-base alloy welds from the Davis-Besse and V.C. Summer plants B. Alexandreanu 1 , O. K. Chopra 1 , W. H. Cullen Jr.

2 and W. J. Shack 1 1 Nuclear Engineering Division, Argonne National Laboratory 2 U.S. Nuclear Regulatory Commission Fontevraud 6, September 18-22, 2006 2 OutlineObjectivesExperiment

-s pecimens-t esting conditions Results and discussion

-cyclic crack growth rates

-S CC crack growth rates

-f ractographySummary 3 ObjectivesObtain crack growth data under both cyclic and constant load conditions in PWR environment on field Alloy 182 weldsDetermine the effect of weld microstructure/orientation on SCC crack growth ratesCompare results with existing CGR database to determine the relative susceptibility of these welds to environmentally assisted cracking.

4 Field weld specimens testedAlloy 1 82 removed from the J-groove weld from Nozzle #11 from the Davis-Besse plant:

J11CC-1 (weld, Alloy 182)

J11CC-3 (weld, Alloy 182)Alloys 182 and 82 from the reactor vessel nozzle-to-pipe from the V. C. Summer plant:

WCR-01 (weld, Alloy 82)

BCR-01 (butter, Alloy 182)

WLR-01 (weld, Alloy 82) 5 Location of specimens -

Davis-Besse J-groove weld of #11 nozzle Cladding Alloy 182 Weld Low-Alloy Steel L Orientation C Orientation C Orientation L Orientation 64 mm 128 mm Weld height at 30° location 29 mm Weld height at 180° location 45 mm 6 Location of specimens -

V.C. Summer reactor vessel nozzle-to-pipe weld 7 Experiment1/2-T compact tension specimens fabricated from both weldsTemp: 316°C (D-B) and 320°C (VCS) PWR Water (<10 ppb DO, 1000 ppm B , 2 ppm Li, 2 ppm h ydrogenFlow Rate:55 mL/minConductivity:20 S/cmPrecracking carried out in the PWR environment to facilit ate the t ransition from transgranular fatigue cracking to intergranular SCC cracking before conducting the constant load testLoad Ratio R:

0.3-precrack; 0.5-0.7-sawtooth with up to 1000s rise time; 1.0-constant loadCrack extension measured by DC potential drop methodFinal crack length confirmed/corrected by actual measurements.

8 Davis-Besse weld alloys 9 Cyclic CGR data for Davis-Besse weld alloys 10-1 2 10-1 1 10-1 0 10-9 10-8 10-7 10-6 10-12 10-1 1 10-10 10-9 10-8 10-7 10-6 J1 1C C-1 (1/4-T C T)J 1 1 C C-3 (1/2-T C T)CG R en v. (m/s)CG R ai r f o r Ni-A l l oy W e l d s (m/s)A l l o y 182 J-Groove W e l d (D av i s-B es s e C R DM N o z z l e #1 1)316°C P W R W a ter CG R env. = C G R ai r + 0.0 18(C G R ai r)0.78 S p eci m en #CGR ai r x 5 10-1 2 10-1 1 10-1 0 10-9 1 0 15 20 2 5 30 35 4 0 4 5 50 1/2-T C T 1/4-T C T E x pe r i menta l C G R (m/s)S t re s s I n t e n s i t y K (M P a*m 1/2)A l lo y 1 8 2 J-G r oov e W e l d D a v i s Be ss e No zz le #1 1 316°C Pro p o s ed Di sp o s it i on C u r v e All o y 182 W e ld M e ta l 10 Fracture surface of specimen J11CC-1 11 V.C. Summer alloys 12 Cyclic and SCC CGRs for V.C. Summer weld alloys 10-1 2 10-1 1 10-1 0 10-9 10-8 10-7 10-6 10-1 2 10-1 1 10-1 0 10-9 10-8 10-7 10-6 WC R-0 1 B CR-0 1 WL R-0 1 CGR en v (m/s)CGR ai r f o r N i-a ll o y W e ld s (m/s)All o y 18 2 S M A W e l d Sim u l a ted P W R W a te r at 320°C 10-1 2 10-1 1 10-1 0 10-9 10 2 0 3 0 40 50 WC R-0 1 B CR-0 1 WL R-0 1 A 8 2 w e ld , J a c k o e t a l.A 1 8 2 b u t t e r , Ja ck o e t a l.E x pe r i m e nta l C G R (m/s)S t re s s I n t e n s it y K (M P a*m 1/2)V.C. S u mm e r N i-A llo y W e l d M e tal 32 5°C Propos ed CG R C u r v e Al loy 182 13 Log-norm a l distribution of constant for several heats of Alloy 82 and 182.

0.0 0.2 0.4 0.6 0.8 1.0 10-1 3 10-1 2 10-1 1 A 1 8 2 A 8 2 A N L B CR-01 A N L W CR-0 1 A 1 8 2 Ja ck o e t a l.A 82 J a c k o et al.C u m u la t i v e Dis t r i b u t i o n F C o nsta n t i n S c ot t Mo de l a t 32 5°C 75t h Pe rce n til e 25t h P e r c en tile M e di an N i-A l l oy W e ld M e ta l 325°C 14 Fracture surface of VCS specimen BCR-01 15 Fracture surface of specimen V.C. Summer BCR-01 16 Fracture surface of V.C. Summer specimen WLR-01 17 Fracture surface of V.C. Summer specimen WLR-01 18 Additional observations 19 Fracture surface of J11CC-1 and BCR-01Cracks across the propagation front appear to impede crack advance 20 Fracture surfaces of Davis-Besse nozzle Alloy 600 specimensFracture mode seems to depend on the location of the specimen 21 SummaryThe cyclic CGRs for Alloy 182 and Alloy 82 weld specimens showed minimal environmental enhancement except for one specimenFor the Davis-Besse Alloy 182 weld specimens, the SCC CGRs under constant load are an order of magnit ude lower than the disposition curve proposed for Alloy 182 weld metals For the V.C. Summer weld specimens, the CGR data under constant load were lower than data obtained by others on the same alloys and lower than the proposed disposition curve