ML061800263
| 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 |
| To: | |
| Shared Package | |
| ML061810190 | List: |
| References | |
| Download: ML061800263 (21) | |
Text
Crack growth rates in a PWR environment of nickel-base alloy welds from the Davis-Besse and V.C. Summer plants B. Alexandreanu1, O. K. Chopra1, W. H. Cullen Jr. 2 and W. J. Shack1 1Nuclear Engineering Division, Argonne National Laboratory 2U.S. Nuclear Regulatory Commission Fontevraud 6, September 18-22, 2006
2 Outline Objectives Experiment
- specimens
- testing conditions Results and discussion
- cyclic crack growth rates
- SCC crack growth rates
- fractography Summary
3 Objectives Obtain crack growth data under both cyclic and constant load conditions in PWR environment on field Alloy 182 welds Determine the effect of weld microstructure/orientation on SCC crack growth rates Compare results with existing CGR database to determine the relative susceptibility of these welds to environmentally assisted cracking.
4 Field weld specimens tested Alloy 182 removed from the J-groove weld from Nozzle #11 from the Davis-Besse plant:
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 Experiment 1/2-T compact tension specimens fabricated from both welds Temp:
316°C (D-B) and 320°C (VCS)
PWR Water (<10 ppb DO, 1000 ppm B, 2 ppm Li, 2 ppm hydrogen Flow Rate:
55 mL/min Conductivity:
20 µS/cm Precracking carried out in the PWR environment to facilitate the transition from transgranular fatigue cracking to intergranular SCC cracking before conducting the constant load test Load Ratio R: 0.3-precrack; 0.5-0.7-sawtooth with up to 1000s rise time; 1.0-constant load Crack extension measured by DC potential drop method Final crack length confirmed/corrected by actual measurements.
8 Davis-Besse weld alloys
9 Cyclic CGR data for Davis-Besse weld alloys 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-12 10-11 10-10 10-9 10-8 10-7 10-6 J11CC-1 (1/4-T CT)
CGRenv. (m/s)
CGRair for Ni-Alloy Welds (m/s)
Alloy 182 J-Groove Weld (Davis-Besse CRDM Nozzle #11) 316°C PWR Water CGRenv. = CGRair + 0.018(CGRair)0.78 Specimen #
CGRair x 5 10-12 10-11 10-10 10-9 10 15 20 25 30 35 40 45 50 1/2-T CT 1/4-T CT Experimental CGR (m/s)
Stress Intensity K (MPa*m1/2)
Alloy 182 J-Groove Weld Davis Besse Nozzle #11 316°C Proposed Disposition Curve Alloy 182 Weld Metal
10 Fracture surface of specimen J11CC-1
11 V.C. Summer alloys
12 Cyclic and SCC CGRs for V.C. Summer weld alloys 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-12 10-11 10-10 10-9 10-8 10-7 10-6 WCR-01 BCR-01 WLR-01 CGRenv (m/s)
CGRair for Ni-alloy Welds (m/s)
Alloy 182 SMA Weld Simulated PWR Water at 320°C 10-12 10-11 10-10 10-9 10 20 30 40 50 WCR-01 BCR-01 WLR-01 A 82 weld, Jacko et al.
A 182 butter, Jacko et al.
Experimental CGR (m/s)
Stress Intensity K (MPa*m1/2)
V.C. Summer Ni-Alloy Weld Metal 325°C Proposed CGR Curve Alloy 182
13 Log-normal distribution of constant for several heats of Alloy 82 and 182.
0.0 0.2 0.4 0.6 0.8 1.0 10-13 10-12 10-11 A 182 A 82 ANL BCR-01 ANL WCR-01 A 182 Jacko et al.
A 82 Jacko et al.
Cumulative Distribution F Constant in Scott Model at 325°C 75th Percentile 25th Percentile Median Ni-Alloy Weld Metal 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-01 Cracks across the propagation front appear to impede crack advance
20 Fracture surfaces of Davis-Besse nozzle Alloy 600 specimens Fracture mode seems to depend on the location of the specimen
21 Summary The cyclic CGRs for Alloy 182 and Alloy 82 weld specimens showed minimal environmental enhancement except for one specimen For the Davis-Besse Alloy 182 weld specimens, the SCC CGRs under constant load are an order of magnitude 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