ML20085F907

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Forwards Summary of Exam Conducted on Beaver Valley Unit 1 SG Tubing,Providing Tenth Refueling Outage SG Tube Results
ML20085F907
Person / Time
Site: Beaver Valley
Issue date: 06/06/1995
From: George Thomas
DUQUESNE LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9506190463
Download: ML20085F907 (35)
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hy g Beaver Vaney Power Station t=;m^ ="- l (412) 643-8069 F AX GEORGES. THOMAS Iu$a"s$Eicei Nuclear Power Division June 6, 1995 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Beaver Valley Power Station, Unit No.1 Docket No. 50-334, License No. DPR-66 Tenth Refueling Outage Steam Generator Tube Pull Results

References:

1. Safety Evaluation by the Office of Nuclear Reactor Regulation Related to Amendment No.184 to Facility Operating License No. DPR-66 Duquesne Light Company Beaver Valley Power Station Unit No. I Docket No. 50-334.

2. Letter from G. S. Thomas (Duquesne Light Company ) to U. S. Nuclear Regulatory Commission, " Response to Information Request Dated December 1,1994," December 13,1994. Enclosed is a copy of the " Summary of Examination Conducted On Beaver Valley Unit 1 Steam Generator Tubing," which is provided to satisfy a commitment identified in References 1 and 2. This submittal provides the examination results within 90 days following restart from the tenth refueling outage. Three tube segments were removed from the " A" steam generator in support of voltage-based tube repair limits specified by interim tube plugging and alternate repair criteria implemented for the current cycle of operation. The tube segments were examined at the Westinghouse Science and Technology Center to characterize corrosion at steam ger rator hot leg support plate crevice locations. P p\\ 9506190463 950606 I-PDR ADDCK 05000334 1 i e P PDR L ( i

.. -.~ Beaver Valley Power St: tion, Unit No.1 I Tenth Refueling Outage Steam Generator Tube Pull Results Page1 If you have any questions regarding the attached information, please contact Mr. G. A. Kammerdeiner, Nuclear Engineering Department, at (412) 393-5677. Sincerely, t $6 w$ ~ - x George S. Thomas Enclosures cc: Mr. L. W. Rossbach, Sr. Resident Inspector Mr. T. T. Martin, NRC Region I Administrator Mr. D. S. Brinkman, Sr. Project Manager i r

SUMMARY

OF EXAMINATION CONDUCTED ON BEAVER VALLEY UNIT 1 STEAM GENERATOR TUBING Introduction Three hot leg steam generator tube segments removed from Steam Generator A of Beaver Valley Unit 1 (Tube R10C48, Tube R22C38 and Tube R28C42) were examined at the Westinghouse Science and Technology Center in support of alternative repair criteria (ARC) applications. The examination was conducted to characterize corrosion at steam generator hot leg support plate crevice locations. The tubes were selected to obtain a sampling of the indications observed in the January 1995 field eddy current inspection. The first, second and third support plate crevice regions (TSP 1, TSP 2 and TSP 3) from Tubes R22C38 and R28C42 and the TSP 1 and TSP 2 region from Tube R10C48 were removed for examination. Five of these eight TSP locations had original field eddy current calls of outside diameter (OD) origin indications. After nondestructive laboratory examination by eddy current, ultrasonic testing, radiography, dimensional characterization and visual examination, two selected support plate regions were leak tested at elevated temperature. Subsequently, room temperature burst testing was conducted on these two TSP regions, as well as the remaining six non-leak tested TSP regions and a free span section from each of the three tubes pulled for ARC applications. Four of the burst tested TSP specimens were destructively examined using scanning electron microscopy (SEM) fractography techniques to characterize the corrosion and two of these four TSP burst tested specimens were further examined using metallography. The remaining four burst tested TSP regions were pulled apart by tensile testing to characterize the effect of intergranular cellular corrosion (ICC) that had been observed within the crevice region adjacent to the burst openings. Both the axial burst openings and the circumferentially torn ICC regions were characterized by SEM fractography techniques. Three of these four TSP regions were then characterized using metaliographic techniques. Overall, all eight TSP intersections had their burst fracture faces characterized by SEM fractography and five of the intersections were further examined using metallography. 1

I NDE Rnso;.n TSP Locations Table 1 presents a summary of the more important field and laboratory NDE results. The eddy current data were reviewed, including reevaluation of the field data, to finaliza the voltages assigned to the indications and to assess the field no detectable degradation (NDD) calls for detectability under laboratory analysis conditions. A single analyst performed this work to minimize data variability. For Tube R22C38, TSP 3 the reevaluation of the original field call produced a significant difference, a 0.60 volt indication versus the original 1.73 volt field call. It was determined that the field call assigned the voltage to the residual signal rather than the flaw voltage to assure that the indication was rotating pancake coil (RPC) inspected in the field. Field and laboratory eddy current inspections (bobbin and RPC probes) produced similar data for most regions examined. For the five originally called field indications at TSP locations, there was little difference in the eddy current bobbin voltage calls between the reevaluated field and laboratory results. The field bobbin data for the three field NDD calls at TSP locations (Tube R10C48, TSP 1 and TSP 2 and Tube R28C42, TSP 3) were reevaluated to derive the most appropriate amplitude measurements, where possible, for these very small signals. This review indicated that one field NDD call (R10C48, TSP 1) could be assigned a bobbin flaw voltage. The reevaluated field RPC data for these three NDD calls continued to be NDD for two of the locations with no discernible flaw separable from the background level. However, one (R28C42, TSP 3) led to a RPC call of a 0.2 volt volumetric indication, even though no bobbin call could be made. In the laboratory, the TSP location with the reevaluated RPC call (R28C42, TSP 3) was identified also to have a bobbin Indication. The reevaluated field bobbin call (R10C48, TSP 1) had a post-pull bobbin indication but was not observed in either the field or laboratory data to have an RPC indication. Some increase in signal strength (voltage) was generally observed in the laboratory eddy current data due to the tube pulling operation. Field bobbin probe signal strengths ranged from 0.44 to 1.73 volts (0.33 to 1.0 volts after data reevaluation) while corresponding post-pull bobbin strengths ranged from 0.45 to 2.1 volts. The largest increase was for Tube R22C38, TSP 3 where the bobbin probe signal strength increased from 0.6 volts to 2.1 volts (with a secondary indication of 0.5 volts). This is considered a moderate increase suggesting that there was some tearing of ligaments between microcracks. All TSP region NDE indications were confined to their crevice regions. Some of the field and laboratory eddy current TSP indications had considerable width in the 2

RPC data, and also in the field and laboratory ultrasonic test (UT) data, suggesting the possibility of intergranular cellular corrosion (ICC) or three dimensional intergranular attack (IGA) in addition to and in association with axial cracking. In general, the laboratory RPC and UT inspection data suggested the presence of even more extensive corrosion at some TSP crevice locations than did the field data. Some of this trend may be related to the tube pulling operation partially opening tight crack networks. Dent signals, absent in the field data, were present in the laboratory data, presumably also resulting from tube pulling operations. I nak Testing Two TSP crevice regions (TSP 3 of Tube R22C38 and TSP 2 of Tube R28C42), those which had the largest voltage (original) field eddy current indications were leak tested at elevated temperature and pressure at conditions ranging from a simulated normal operating condition to a simulated steam line break condition. None developed leaks. Table 2 presents test condition data for the specimens. Rorst and Tnnsiin Testing TSP Locations All eight pulled TSP crevice regions and three free span regions were burst tested at room temperature at a pressurization rate of 2000 psi per second. The burst tests were performed simulating free span conditions w;th no TSP enveloping the indicati3ns. In addition, the five field indication specimens were tested using a bladder arid foil for the burst tests with a " semi-constraint" condition which simulated the lateral constraint provided by the TSPs located below and above the crack irdication at prototypical spacing between TSPs. Results of the burst tests are presented in Table 3. All burst specimens developed axial burst openings. The openings for the TSP crevice region specimens were centered within the crevice regions. The circumferential positions of the burst openings in the support plate crevice region specimens were close to the location of the deepest laboratory UT indications for the specimens that had corrosion indications. The eddy current RPC data does not provide an absolute circumferential position. All TSP specimens burst at high pressures. The lowest burst pressure for the TSP crevice regions (Tube R22C38, TSP 1, a 0.7 volt field bobbin indication) was 9,712 psi, 80% of the burst pressure of its free span equivalent. Following burst testing, a visual inspection showed the presence of wide-spread ICC, that was confined to the crevice region. As a consequence, four of the burst specimens (Tube R22C38, TSPs 2 and 3 and Tube R28C42, TSPs 1 and 2) were tensile tested at room temperature to obtain tensile strength data and to pull apart i the ICC networks for subsequent destructive examination. These four specimens 3 l l l

4 had high tensile loads, with the lowest being 11,420 psi (R22C38, TSP 2). Table 3 provides the tensile properties obtained on these four specimens, as well as from a nonburst tested, free span section from each of the pulled tubes. The tensile and burst strengths for the free span sections are typical for Westinghouse tubing of this vintage, although the strengths of Tubes R10C48 and R22C38 are semewhat on tn high side. Destructive Frnminatinn Ranults TSP Locations A summary of post-burst test visualinspection data and of burst property data related to the presence of corrosion is presented in Table 4 for each of the burst TSP region specimens. The data in Tabla 4 were used to plan destructive examination work efforts. Corrosion cracks were observed on all eight of the TSP specimens. These eight specimens werc candidates for destructive examination. The free span sections of Tubes R10C48, R22C38 and R28C42, selected for a reference burst pressure and tensile property test, had no degradation, as would be expected. Two of the four specimens, shown in Table 4, that were burst tested, but not tensile tested, were selected for complete destructive examination of their crevice region corrosion. These examinations included SEM fractography of the burst openings and metallography of secondary corrosion within the crevice regions. The other two were characterized by SEM frac,tography of their burst openings, in addition, three of the four specimens, shown in Table 4, that were burst and then tensile tested, were selected for complete destructive examination, that included SEM fractography of both their axial burst openings and their circumferentially tensile torn fracture faces, as well as metallography of secondary crevice region corrosion. The fourth burst and tensile tested specimen was characterized by SEM fractography of both its axial burst opening and its circumferentially tensile torn fracture face. The burst fracture faces of these eight TSP crevice region specimens were opened for SEM fractographic examinations. Table 5 presents the results of the t fractographic data in the form of macrocrack length versus depth, macrocrack length / average and maximum depth, and the number / location / width of ductile or uncorroded ligaments found on the fracture face. The burst openings occurred in axial macrocracks that were composed of numerous axially oriented intergranular microcracks of OD origin. Ductile ligaments separating the microcracks were present in six of the eight examined TSP specimens. The data of Table 5 indicate that most of the TSP regions from Beaver Valley Unit 1 pulled tubes had a typical number of remaining uncorroded ligaments between microcracks comprising the [ burst macrocracks. All intergranular corrosion was confined to and centered t 4

l within the crevice regions. The burst opening corrosion macrocracks for the TSP crevice regions had maximum depths ranging from 22% to 61% throughwall, with average depths ranging from 11% to 38% throughwall and with macrocrack lengths ranging from 0.068 to 0.750 inch. 1 Three TSP regions were initially called bobbin NDD in the field and one (TSP 1 of Tube R10C48) was subsequently found by reevaluation of the field data to have a small (0.28 volt) indication prior to the tube exam. (A second TSP region, TSP 3 of Tube R28C42, was found by data reevaluation to have a small,0.2 volt, field RPC volumetric indication.) The maximum crack depths for these three locations were 47%,22%, and 34% for the TSP 1 and TSP 2 region of Tube R10C48 and the TSP 3 region of Tube R28C42, respectively. The corresponding average { macrocrack depths were 36%,11% and 17%, respectively. j The circumferential tensile fracture faces of the four TSP crevice region specimens that were opened by tensile testing were examined by SEM fractography to characterize their ICC networks. Table 6 presents the results of the fractographic data in the form of ICC depth versus circumferential position, ICC network length, ICC network average depth (averaged over the entire tube circumference and normalized to pre-burst and pre-tensile test dimensions), and the number of ductile or uncorroded ligaments found within the ICC networks on the fracture faces. The ICC networks had similar ICC average depths that ranged from 8% to 16% deep and ICC network lengths that langed from a total length of 111 to a total of 270. The individual ICC depth data were obtained from the local ICC front which was relatively uniform in depth. These individual ICC depth data ignored any deeper axial cracks which occasionally penetrated the ICC front. Figures 1 to 8 present sketches of the crack distributions found by visual (30X stereoscope) examinations. The sketches show the locations where cracks were found and their overall appearance, not the exact number of cracks or their detailed morphology. All TSP regions had their corrosion centered within and confined to the crevice regions. Due to the complexities of the crack networks observed in the TSP regions, radial metallography was utilized, in addition to transverse metallography, to provide an overall understanding of the intergranular corrosion morphology for the five TSP regions that were selected for metallographic characterization. In radial metallograpny, small sections of the tube (typically 0.5 by 0.5 inch) are flattened, mounted with the OD surface facing upwards and then progressively ground, polished, etched and viewed from the OD surface towards the inside diameter (ID) surface. Table 7 provides a summary of the metallographic data. It can be noted that the maximum depth for Tube R22C38, TSP 1 from the transverse metallographic section was 65% compared to the maximum depth of 52% for the l l l l l 5 l i 1 l ________________________________________________________________________-.._____________________________-.______________________j

burst crack face (SEM fractography). In this case, the maximum crack depth did not contribute to the weakest macrocrack which burst. For the other TSP regions, the maximum depth was found on the burst crack face. From the metallographic examinations conducted on the five selected TSP regions, it was concluded that the dominant OD origin corrosion morphology was axial IGSCC. In addition, in all five cases for the TSP regions, there were areas or patches with ICC found in association with the axial IGSCC. The most significant ICC (in area) occurred in the cases of TSP 2 and TSP 1 of Tube R28C42. With an ICC morphology, a complex raixture of short axial and oblique angled cracks interact to form cell-like structures. Figure 9a provides an example of the ICC morphology found in the case of TSP 2 of Tube R28C42 at a depth of 14% below the OD surface. With progressive radial grinding, it was shown that the axial IGSCC became more dominant with depth while the ICC tended to disappear more quickly. Figure 9b shows the same location shown in Figure 9a, but at a depth of 34%. Only axial IGSCC remains at this depth. The maximum depth of ICC was always less than that of the axial IGSCC present at the same location. However, the depth of ICC frequently was close to that of the more dominant axialIGSCC. Finally, in some areas, especially where the cracking occurred at very high densities, shallow IGA also was present. The IGA always was significantly less deep than the surrounding ICC. IGSCC morphology can be characterized by depth / width (D/W) ratios where the extent of IGA associated with a given crack is measured by the ratio of crack depth to the width of the crack at its mid-depth. D/W ratios greater than 20 are defined as minor and ratios less than 3 are defined as significant. Crack density is also considered an important parameter in characterizing corrosion. Crack densities greater than 100 cracks in 360 degrees are defined as high while values less than 25 are defined as low. The OD origin axial intergranular corrosion observed in TSP crevice regions of the Beaver Valley Unit 1 tubes had little variation in crack densities or in crack morphologies. The crack density ranged from the high side of moderate to high and the crack morphology was typically moderate with values ranging from minor to high, as measured by D/W ratios. Note, that all individual D/W ratios that were low (D/W <3) were associated with i very shallow cracks. As many sha low cracks were present, the reported average D/W ratios were somewhat low compared to those typically reported for other plants where the corrosion is deeper. Table 7 presents the metallographic data. Specimen R28C42, TSP 2 had the largest number of cracks (an estimated 186 cracks over the tube circumference for the center of the crevice region) with most associated with a large 250 long ICC zone. The largest average D/W ratio (22) occurred in Specimen R22C38, TSP 1 and the lowest average D/W ratio (3) occurred in Specimen R10C48, TSP 1, where most cracks were very shallow. 6

Conclusinns TSP L ocations All eight of the TSP crevice regions of Tubes R10C48, R22C38 and R28C42 had OD origin corrosion present. Metallographic data showed that the corroded TSP crevice regions had combinations of axially oriented IGSCC and ICC with the axial IGSCC predominating. All corrosion was confined to :.k revice regions. The corrosion morphology was typical of pulled tubes within the Electric Power Research Institute (EPRI) database. Eddy current bobbin and RPC probe data correlated well with the corrosion distribution for the deeper cracks. Three TSP crevice regions were initially called bobbin NDD in the field ar.d two were subsequently found by reevaluation of the field data to have small (0.28 volt by bobbin for one and 0.2 volt by RPC for the other) indications prior to the tube exam. These two regions had corrosion ranging from 34% to 47% throughwall maxir 71 depth,17% to 36% throughwall average depth while the third NDD region hat.,rrosion up to 22% maximum depth,11% average depth. Consequently, the latter location had corrosion below the eddy current detection threshold and the other two had corrosion near the eddy current detection threshold. These three locations also serve in determining the UT detection threshold. One (the deepest one, TSP 1 of Tube R10C48) of the three was called by field UT inspections as having corrosion while all three were called by lab UT inspections as having corrosion. Consequently, these locations also had corrosion near the UT detection threshold. The TSP crevice region burst pressures ranged from 9,712 to 12,891 psi. All burst pressures were well above safety limitations required by R.G.1.121 and close to free span burst values, i.e., those without corrosion. The burst pressure data were consistent with expectations and near or above mean predictions for the ARC burst pressure versus bobbin voltage correlation. Tensile tests performed on four of the TSP regions with extensive ICC also showed high strength for the specimens. 7

e Table 1 Comparison of NDE Indications Observed at Beaver Valley Unit 1 on S/G Tubes at Hot Leg Locations Tube / Field E/C Lab E/C Field UT Lab UT Lab X-Ray Location

R10C48, Rnhhn: NDD (0.28V DI)*

Bobbut O.45V DI,50% Small patch OD axial Small patch OD axial inds + Short Circ ind at TSP 1 BEC: NDD deep; 1.9V dent inds separate patch Cire inds at SP bottom, RPC: NDD crevice bottom possible ICC

R10C48, Rnhhn: NDD Rnhhn: 2V dent NDD Short Circ Ind at crevice NDD TSP 2 BEC: NDD RPC: NDD bottom I anarvf nf Ahhrnvintim 0* = field reevaluation value (corrected for TSP = Support Plate V = Voltage Circ = circumferential cross calibration)

!nd = Indication MAI = Multiple Axial Max = maximum NDD = No Detectable Degradation SAI = Single Axialind inds DI = Distorted Indication RPC= Rotating Pancake Coil E/C = Eddy Current Test

  1. C = number of cracks ICC = intergranular cellular corrosion UT = Ultrasonic Test t-i

-r w w g- ~w rm-w -a y- ~ r.,,,.s, ,,w.,., - ,r,, y g- .,-g 3- +,,, mm -

. -- n

Table 1 (Continued) Comparison of NDE Indications Observed at Beaver Valley Unit 1 on S/G Tubes at Hot Leg Locations Tubel Field E/C Lab E/C Field UT Lab UT Lab X-Ray Location

R22C38, Rnhhtn; O.64V DI (0.7V Rohhin 0.9V DI (36%

Two patches OD axial Inds, Three patches of OD axial Faint spider-like TSP 1 Ind,37% deep)* deep) plus two distorted plus one short Circ Ind and Circ Inds,40% max Inds within BP_C: NDD (2 patches, dents (1.2V & 3.9V) depth crevice region 0.2 & O.3V,88 & 52% BEC: many patches,0.25 deep)* & O.55V, up to 93% deep

R22C38, Rnhhin 0.44V Di (0.33V Rnhhin 0.7 & O.7V Inds, Three patches OD axial inds Three groups of OD axial NDD TSP 2 Dl, 76% deep)*

up to 84% deep; 3V dent and Circ Inds,40% max BEC: sal (0.14V Ind with BEC: many patches, depth many patches,58% 0.38V, up to 84% deep deep)

R22C38, Rnblun: 1.73V Di (0.6V Rnhhin: 2.1 & O.5V Inds, Possible shallow OD axial Patch of OD axial and Circ Possible MAI (2),

TSP 3 DI)

  • up to 76% deep & 2.3V Inds within crevice deposit inds, with O.29* SAIin 0.25" max, BEC: 0.41" SAI (0.5V, dent signals patch,35% deep within crevice 120 patch,62% deep &

BEC: 0.7V,120 patch region 0.27V sinali patch,65% deep i

t f Table 1 (Continued) Comparison of NDE Indications Observed at Beaver Valley Unit 1 on S/G Tubes at Hot Leg Locations Tubel Field E/C Lab E/C Field UT Lab UT Lab X-Ray Location

R28C42, Rahhan: 0.72V DI (0.56V Rnhtun: DIin 2V dent One patch OD axial Inds Large patch (1801 OD NDD TSP 1 Ind,66% deep)*

BPI.: two patches, 60% axial and Circ Inds, 30% BEC: SAI (0.29 & O.15V deep max depth patches, up to 62% deep)* t

R28C42, Rnhhan: 1.12V DI (1.OV Bobbui: 1.OV Dl,75%

Shallow OD SAI within 120' patch OD axial and Possible faint SAI, TSP 2 Ind,53% deep)* deep; 2.9V dent crevice deposit signals Circ inds at mid-crevice to 0.1"long BEC: 0.44' SAI (0.3V BEC: 0.66V 180' TSP bottom,30% max 180* patch,53% deep)* volumetric Ind, 83% deep depth

R28C42, Rnhlun: NDD Rohhin: 0.6V DI in 4V dent NDD Small spot with OD axial NDD TSP 3 BEC: NDD (0.2V BEC: noisy data and Circ response,20%

volumetric Ind, 59% max depth deep)* ? E

A i I Table 2 Beaver Valley Unit 1 Leak Test Results for Steam Generator Tubing Tube No., Test Type: Leak Rate Test Conditions Location Differential (liters / hour) Pressure (psil P, = 2294, P,= 962, T, = 615, T, = 612 R22C38, TSP 3 NOC: 1332 zero P,= 2434, P = 515, T,= 622, T,= 618 ITC1: 1919 zero SLB: 2588 zero P.= 2783, P, = 195, T, = 622, T, = 613 R28C42, TSP 2 NOC: 1257 zero P,= 2216, P = 959, T,= 612, T,= 606 ITC1: 1894 zero P,= 2416, P,= 522, T,= 620, T,= 605 SLB: 2560 zero P, = 2770, P, = 210, T, = 622, T, = 593 i Legend: All data within a table block is presented in the order of testing, NOC = normal operating conditions, ITC = intermediate test conditions, SLB = steam line break conditions, P,= primary side pressure (psi), P = secondary side pressure (psi), T,- primary side temperature ( F), T,= secondary side temperature ( F) f

Table 3 Room Temperature Burst and Tensile Test Results for Beaver Valley Unit 1 Hot Leg S/G Tubing Location Burst Ductility Burst Length Burst Width Tensile 0.2% Offset Tensite UTS Tensile Pressure (% Dia.) (inches) (inches) Fracture Tensile YS (psi) Elongation (psig) Load (lbs) (psi) (%) R10C48,FS 12,964 31.3 2.078 0.406 15,270 65,700 115,700 29.3 R10C48, TSP 1 11,968 19.0 1.507 0.366 R10C48, TSP 2 12,891 26.3 1.869 0.449 R22C38,FS 12,056 28.8 1.780 0.356 14,730 63,000 111,600 29.8 R22C38, TSP 1 9,712 + 14.4 1.301 0.305 R22C38, TSP 2 10,254 + 13.8 1.357 0.348 11,420' NM NM NM R22C38, TSP 3 10,576' 15.8 1.295 0.296 12,000' NM NM NM R28C42,FS 12,100 32.3 1.924 0.408 14,320 58,450 106,050 32.0 R28C42, TSP 1 11,353' 22.7 1.527 0.380 13,750' NM NM NM R28C42, TSP 2 10,503 + 19.4 1.401 0.350 12,500* NM NM NM R28C42, TSP 3 11,792 23.5 1.598 0.423 Control 11,440 no data no data no data 51,450 105,700 30.2 (NX8161) 11,455 32.7 1.965 0.365 Legend: TSP = support plate crevice region location; FS = free span location: NM - not meaningful, as data was obtained from a tensile test of a burst specimen + = Burst specimen used a bladder and foil over largest defect area and was burst in a semi-restraint condition. All other burst specimens were burst without bladders and foils and without a restraint conditions.

  • = These four tensile specimens were tensile tested following burst testing.

o

Table 4 ~ Beaver Valley Unit 1 Destructive Examination Planning Data for TSP Specimens Specimen E/C Data (field Burst & Ductility FF Crevice Region

  • Corrosion (visually DE Plan bobbin probe)

Ratios Corrosion

  • observed)

(specimen / FS (visually value) observed) R10-C48, FS NDD 1.00/1.00 No No No R10-C48, TSP 1 NDD (0.55VDI) 0.92/O.61 Yes Yes,70 ICC patch + axial cracks Yes, both metallography and SEM FF - at TSP bottom edge R10-C48, TSP 2 NDD O.99/O.84 Yes Yes,30"ICC patch + random axial Yes, SEM FF only cracks R22-C38, FS NDD 1.00/1.00 No No No R22-C38, TSP 1 0.64V DI (0.7V Ind) 0.80/O.50 Yes Yes, mostly axial cracks over 360* Yes, both metallography and SEM FF R22-C38, TSP 2 0.44V DI (0.33V DI) 0.85/O.48 Yes Yes,80 ICC patch + other minor Yes, both metallography and SEM FF cracks (after tensile testing of burst specimen) R22-C38, TSP 3 1.73V DI (0.6V DI) 0.88/O.55 Yes Yes,80 ICC patch + 2 fong sal Yes, both metallography and SEM l-F (after tensile testing of burst specimen) R28-C42, FS NDD 1.00/1.00 No No No R28-C42, TSP 1 0.72V Di (0.56V Ind) 0.94/O.70 Yes Yes,120'ICC patch + 2 fong SAI Yes, SEM FF only (after tensile testing of burst specimen) R28-C42, TSP 2 1.12V Di (1.OV Ind) 0.87/O.60 Yes Yes,360 ICC at TSP bottom edge Yes, both metallography and SEM FF + 140 ICC patch (after tensile testing of burst specimen) R28-C42, TSP 3 NDD O.97/O.73 Yes Yes,60 ICC patch Yes, SEM FF only

  • = All bursts occurred centered within the crevice regions.

E/C = Eddy Current Test SEM = Scanning Electron Microscopy FS = free span: TSP = tube support plate; FF = fracture face DE = Destructive Evaluation

Table 5 Beaver Valley Unit 1 S/G Tube Burst Opening Macrocrack Profiles

Tube, Length vs. Depth & Ductile Ligament Data Positional Information Comments Specimen (inches /% throughwall)

R10C48, TSP 1 0.00/00 <-Ligament 110.007" wide Crack Bottom (located 0.016" above The axially oriented 0.04/36 TSP bottom) burst macrocrack had 0.08/40 three ductile 0.12/44 ligaments with 0.16/40 dimple rupture 0.20/38<-Ligament 2/0.003 wide features occurring 0.24/44 <--Ligement 3/0.020" wide over more than 50% 0.28/32 of their length. 0.32/47 <-(Max. depth = 47%) (0.346/00) (Ave, depth = 36%, Macrocrack Crack Top Length = 0.346 inch) R10C48, TSP 2 0.00/00 Crack Bottom The axially oriented 0.01/08 burst macrocrack had 0.02/14 one ductile ligament 0.03/22 <-(Max. depth = 22%) with dimple rupture 0.04/12 features occurring 0.05/00 <-Ligament 1/0.020" wide over more than 50% 0.06/18 of its length. (0.068/00) (Ave. depth = 11%, Macrocrack Crack Top (located 0.20" below TSP Length 0.346 inch) top) l l l l l t

Table 5 (Continued) Beaver Valley Unit 1 S/G Tube Burst Opening Macrocrack Profiles j

Tube, Length vs. Depth & Ductile Ligament Data Positiorsal Information Comments Specimen (inches /% throughwall)

R22C38, TSP 1 0.00/00 Crack Bottom (located 0.052* above TSP The axially oriented 0.05/18 bottomi burst macrocrack had 0.10/25 no ductile ligaments 0.15/29 with dimple rupture 0.20/42 features occurring l 0.25/30 over more than 50% 0.30/28 of their lengt l 0.35/52 <-(Max. depth = 52%) 0.40/42 j O.45/18 0.50/25 0.55/25 0.60/18 0.65/20 (0.675/00) (Ave. depth = 26%, Macrocrack Crack Top Length = 0.675 inch) R22C38, TSP 2 0.00/00<-Ligament 1/o.004" wide Crack Top & Location of TSP Top The axially oriented 0.05/32 burst macrocrack had 0.10/24 twelve ductile 0.15/18<-Ligament 2/0.008 wide ligaments with 0.20/46<-Ligaments 3 & 4/o.003 & o.007 wide dimple rupture 0.25/52<-Ligament 5/0.002" wide features occurring 0.30/45 over more than 50% 0.35/48 of their length. 0.40/54<-Ligament 6/0.001 wide 0.45/54<-Ligament 7/o.001 wide <-Tensile Fracture Location 0.50/42 <-Ligament 8/0.0014" wide (0.53/61)<--(Max. depth = 61%) 0.55/57 <-Ligament 9/0.004" wide 0.60/50<-Ligament 10/0.007 wide 0.65/46 <-Ligament 11/0.002 wide 0.70/41 <-Ligament 12/o.002* wide Crack Bottom & Location of TSP Bottom 0.75/00 (Ave. depth = 38%, Macrocrack Length ] = 0.750 inch)

A Tabla 5 (Continued) Beaver Valley Unit 1 S/G Tube Burst Opening Macrocrack Profiles

Tube, Length vs. Depth & Ductile Ligament Data Positional Information Comments Specimen (inches /% throughwall)

R22C38, TSP 3

  1. 8080<-t,mei a tw teor
  • MT,eistT tamaa The axially oriented 4

0J5/4e burst macrocrack had M4) <-{% depth = 54%) nine ductile CJ5/48 <-tea wn tsanien ligaments with 0.20/42<-Upm LtOC5% dimple rupture 1 l 12M2<-te== Woer e features occurring { over more than 50% sm<-t,aw woora of their length. 1 45/42 030/46 035/34,_p gm.a 0AM2<_4, euser* 035/24<-t,==t a nees a aosra 1 70/12 (OJ06AC) (A _ depth = R Manenwh tergh = 0J06 inrh) M Bottom R28C42, TSP 1 08080<-t, i tassi.misra Mig tisPT,tscaisa The axially oriented <-t, miuwme mas,Jord burst macrocrack had g thirteen ductile tl5ao, g,, 0.29/M ligaments with 8M dimple rupture (oJM1)<--(ww 52%) features occurring over more than 50% l RJsne <_t a %im 188 of their length. 145/41<-ticaw ensera 850/43<-t,nw near a j 035/e<-t,==is aiuhmsomea O<-t,mt 114.00r a 5/*<-t,wn IMuler a num n w = n -,t,s=tu m M w. l

Ttble 5 (Continued) Besver Va.Iley Unit 1 S/G Tube Burst Opening Macrocrack Profile 2

Tube, Length vs. Depth & Ductile Ligament Data Positional Information Comments Specimen (inches /% throughwall)

R28C42, TSP 2 0.00/00 Crack Top & TSP Top Location The axially oriented 0.05/12 burst macrocrack had 0.10/10 twelve ductile 0.15/08 ligaments with 0.20/36 dimple rupture 0.25/33<-Ligament 1/0.001 wide features occurring 0.30/32<-Ligaments 2 & 3/o.013 & o.005 wide <-Tensile Fracture Location over more than 50% 0.35/41 <-Ligament 4/o.027 wide of their length. (0.34/44)<-(Max. depth = 44%) 0.40/42 <-Ligaments 5 & 6/0.002 & o.004" wide 0.45/40<-Ligament 7/o.001 wide 0.50/40 <-Ligament 8/0.0043 wide 0.55/38<-Ligament 9/o.008' wide 0.60/30 <-Ligaments 10,11,12/.004,.002,.013* wide 0.65/16 0.70/04 (0.732/00) (Ave. depth = 25% Macrocrack Crack Bottom Length = 0.732 inch) R28C42, TSP 3 0.00/00 Crack Bottom (located 0.022" above The axially oriented 0.05/16 TSP bottom) burst macrocrack had 0.10/14 no ductile ligaments 0.15/10 with dimple rupture 0.20/14 features occurring I 0.25/14 over more than 50% 0.30/18 of their length. O.35/27 0.40/34 <-(Max. depth = 34%) 0.45/24 0.50/28 0.55/20 0.60/16 0.65/14 0.70/10 (0.718/00) (Ave. depth = 17%, Macrocrack Crack Top Length = 0.718 inch) l

Table 6 Beaver Valley Unit 1 S/G Tube ICC Network Profiles on Tensile Fracture Faces Tube, Location Circ Position vs. ICC Depth Comments (deDrees/% throughwall) R22C38, TSP 2 8/20 4 There were two main ICC (15/0) <- c hc=k sliip ' reworks. Networks #1 & 2 30/0 ware 20' and 91* long, 52/0 respectively. There were 3 75/O ductile ligaments present within (77/0) <- c hewn altp these ICC networks. 98/16 120/44 <- Ai httemien 142/40 165/8 (168/0) <- u ne wk#20, 188/8 210/0 232/0 255/0 (265/16) <-la pinhf % 15 m depth 278/0 300/0 322/0 345/0 (355/0) <- c he wn slii, (An. depth = 8% around enginal tube)

i l Table 6 (Continued) Beaver Valley Unit 1 S/G Tube ICC Network Profiles on Tensile Fracture Faces Tube, Location Circ Position vs. ICC Depth Comments (degrecs/% throughwall) R22C38, TSP 3 0/0 There were four main ICC (5/0) <- n wt sir, networks. Networks #1,2,3 & 22/7 4 were 42',125',15*, and 15' 45/1 fong, respectively. There were (47/0) <- n wt sir, 18 ductile ligaments present 68/0 within these ICC networks. (75/10) <- u pmA 4' ions,10% m. hph 90/0 (95/0) <- c ht s2 r, 112/34 135/42 158/40 180/44 <- bW bunt leson 202/40 (220/0) <- a wt alt, 225/0 (240/0) <- a wk sir, 248/16 (255/0) <-lct wt #3 r, 270/0 (285/0) <- ra wt #4 7, 292/10 (300/0) <-Kt w t#47, 315/2 <- u pmA 5'lons,2% =. *pth 338/0 (Ave hpth = 15% mund wirinaltube)

l i i l Table 6 (Continued) i Beaver Valley Unit 1 S/G Tube ICC Network Profiles on Tensile Fracture Faces Tube, Location Circ Position vs. ICC Depth Comments (degrees /% throuDhwall) R28C42, TSP 1 0/0 There were three main ICC (15/0) <- c hk alt, networks. Networks #1,2, & 3 22/4 were 17*,20 and 233'long, (32/0) <- c ht.wk si r, respectively. There were 29 45/0 ductile ligaments present within (60/0) <- c ht #2 Tip these ICC networks. 68/3 (80/0) <- E wk #2 r, 90/0 (92/0) <- a wi *j r, 112/24 135/12 158/35 180/28 <- Asihunt koen 202/32 225/16 248/16 270/10 292/8 315/2 (325/0) <-a w ksir, 338/0 (An. depth = 12% Fewd Nigialtuht) ~!

1 I i l I i Table 6 (Continued) Beaver Valley Unit 1 S/G Tube ICC Network Profiles on Tensile Fracture Faces Tube, Location Cire Position vs. ICC Depth Comments (degrees /% throughwall) R28C42, TSP 2 8/35 The 250'long ICC network had 30/36 11 ductile ligaments present 52/28 within the main ICC network, 75/12 98/10 120/11 142/6 (160/0) <- u newir, 165/0 (170/18) <-EpitA5'iens,18%mdepth 188/0 210/0 232/0 255/0 (270/0) <- tu Nc=k r, 278/22 300/26 < - hai Bunt tusen 322/30 345/34 (Ave. depth = 14% arewd oripnal tuk) 4 I 1

h Table 7 Metallographic Data of Beaver Valley Unit 1 Steam Generator Tubes. Specimen Section Type Number Section Cracks Estimated Maximum Max 1 Avg. Depth Max. Depth ofICC Tranmrse Avg. DM Ratio ofCracks Length per Inch Number of Cracks at (% Throughwall) and Axial Components (% from Transverse (Inch) Mid-crevice Location nroughwallin Radial Section) Section R10C48,TSPI Tre:sverse 39 2.18 18 90 20/4 10%< Oblique <32% 3* Radial 16 0.37 43 depth = 4 % ' 32%< Axial <60% Radial 19 0.39 48 depth = 10 % Radial 7 0.40 18 depth = 32% Radial 0 0.40 0 depth = (4 % R22C38, TSP 1 Transverse 44 2.16 20 77 65/33 28%< Oblique <48% 22 Radial 12 1.40 30 depth = 4 % Axial <48% Radial 11 0.42 26 depth = 10 % Radial 9 0.42 21 depth = 28% Radial 1 0.42 2 depth = 48 %

  • De Small value of the DM (IAph/ Width) ratio is biased by the counting of many shallow cracks. The average DM ratio for the larger cracks having an average depth of 13%

throughwall was 9. These vahx:s are consistent with the trend of observing larger DM ratios for deeper cracks. t

L Table 7 Metallographic Data of Beaver Valley Unit i Steam Generator Tubes (Continued) Specimen Section Number Section Cracks Estimated Maximum Max 1 Avg. Max. Depth of ICC Transverse Avg. D/W Ratio Type of Length per Number of Cracks at Depth (% and AxialComponents(% from Transverse Cracks (Inch) Inch Mid-crevice Location Throughwall) Throughwall in Radial Section) Section R22C38, TSP 2 Transverse 33 2.51 13 70 43 /24 16< Oblique <38 9 Radial 17 0.42 40 depth = 2 % 38< Axial <60 Radial 12 0.44 27 depth = 16 % Radial 4 0.44 9 depth = 38 % Radial 0 0.44 0 depth = 60 % R22C38. TSP 3 Transverse 40 2.52 16 126 40 / 23 38< Oblique <60 10 Radial 26 0.30 87 depth = 2 % 38< Axial <60 Radial 29 0.38 76 depth = 16 % Radial 10 0.43 23 depth = 38 % Radial 0 0.43 0 depth = 60 % R28C42, TSP 2 Transverse 149 2.65 56 186 21 / 13 6 Radial 1 18 0.38 48 depth = 2 % 16< Oblique <34 Radial 1 23 0.47 49 depth = 16 % 34< Axial <56 Radial I 5 0.49 10 depth = 34 % Radial 1 0 0.49 0 depth = 56 % Radial 2 30 0.49 61 depth = 2 % 14< Oblique <34 Radial 2 30 0.49 61 depth = 14 % 34< Axial <52 Radial 2 10 0.49 20 depth = 34 % Radial 2 0 0.49 0 depth = 52 % l l I

I I I i 1.25 - g TSP Top s' $[- Yh'{ i,' / i, ' y F$b 2 a M 0.75 - TSP Bottom as lu l 0.00 i i i 270* 0* 90* 180-270* Circumferential Position (degrees) Figure 1 Sketch of the OD surface crack distribution found at the first tube support plate (TSP 1) region of Tube R10C48 following burst testing. Also shown is the location of the axial burst opening. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.) s

1 2.00 I I I 5 2o.c U .c 1.15 - q,k, y...-,'I'tr , ', -TSP Top ' 1 d,. 3 y.. i, 'l i l j e,. '/I ' ^ " ', ".g. p,,. i a 1 r <,1 N' '.s. f,.,, B i' El 0.40 - -TSP Bottom J 0.00 i i i o' 90* 180" 270* 360* Circumferential Position (degrees) Figure 2 Sketch of the OD surface crack distribution found at the second tube support plate (TSP 2) region of Tube R10C48 following burst testing. Also shown is the location of the axial burst opening. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.) J

w l I I 1.75 I U 1~25- -TSP Top y l 4 'A 'j'l \\ {d i' $ /

  • hl/

L 5 c \\ f> i \\ \\ III li[ )\\ I 5l1 O I I ,b iy ,'il I ,I l p y. e e 's s o! h,, Jk' 1 " ), ,l /' ' dd,t t 0.50- -TSP Bottom m 0.00 i l 0* 90' 180* 270* 360* Circumferential Position (degrees) t i Figure 3 Sketch of the OD sudace crack distribution found at the first tube support plate (TSP 1) region of Tube R22C38 following burst testing. Also shown is the location of the axial burst opening. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

I I I 1.'15 U 1.25-g } ) - TSP Top g9 v Ot**' i / 4 i ,\\ ' >L1' \\ o 0.50-E1 -TSP Bottom 0.00 i 0* 90' 180* 270" 360" Circumferential Position (degrees) Figure 4 Sketch of the OD surface crack distribution found at the second tube support plate (TSP 2) region of Tube R22C38 following burst testing and following subsequent tensile testing. Also shown are the locations of the axial burst opening and the circumferential tensile fracture. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

I I l 1.75 l' 0 1.25- -TSP Top rs t lf .5 I I ~ i i q

1 M

a 4 [ O (!,8'i 11 1 t)( )! c L ',\\ki,ti l i)' '5 i' I..'t.,g y 0.50- -TSP Bottom 0.00 l l l 0* 90* 180* 270* 360" Circumferential Position (degrees) Figure 5 Sketch of the OD surface crack distribution found at the third tube support plate (TSP 3) region of Tube R22C38 following burst testing and following subsequent tensile testing. Also shown are the locations of the axial burst opening and the circumferential tensile fracture. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

I I I 1.75 i 1'25 ^ U I! i,l i Y f - TSP Top

  • ! 'ff dg L)'! a g y,NT'l'1 t o 3

g g Y '] } ;t '( t }lg t' y fr ). \\ l i< l 1 g yt, e 9 a a _ _ t. n n je(, i 'l{ 3 \\ M ',.. - h'l 3 --. hy a l, n = [' 't g 4 .9 y '{ 0),kQ 1' g auff\\d'y u 3 0.50- -TSP Bottom m i 0.00 l i 0* 90* 180* 270* 360" Circumferential Position (degrees) Figure 6 Sketch of the OD surface crack distribution found at the first tube support plate (TSP 1) region of Tube R28C42 following burst testing and following subsequent tensile testing. Also shown are the locations of the axial burst opening and the circumferential tensile fracture. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

1 I I I 1.75 j 1.25-j, -TSP Top s A p,i '5,, .c j I j fu j Wi&hWhy4 3 f... m 0.50- - FSP Bottom IIi J 0.00 i i i 0* 90' 180" 270* 360" Circumferential Position (degrees) Figure 7 Sketch of the OD sudace crack distribution found at the second tube support plate (TSP 2) region of Tube R28C42 following burst testing and following subsequent tensile testing. Also shown are the locations of the axial burst opening and the circumferential tensile fracture. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

1.75 I I I ) 1 2 .E 1.25-M N':.T(.y .' r <sp tygg-p is.. - TSP Top e 5 \\, i, i 3 h 1$ i < fl !) t, 11!' 3 l v 1J, ,,'pl/ ,e s q' y *l v i e, tt t ' I ' * 'Y ' 5 O!J N 0.50- 4 -l,SP Bottom 0.00 i 0' 90* 180* 270* 360* Circumferential Position (degrees) Figure 8 Sketch of the OD surface crack distribution found at the third tube support plate (TSP 3) region of Tube R28C42 following burst testing. Also shown is the location of the axial burst opening. (The burst opening extended beyond the TSP crevice region, but the corrosion cracking on the burst fracture was confined to the crevice region.)

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7 . y...u., s.:.t yJa... .e NIs, lk'. Tensile Fracture Face u. i .c v.M< ' au4 z I ,i Figure 9a Radial rnetallographic section showing the TSP 2 region of Tube R28C42 at a depth of j 14'- below the OD surface. Intergranular cellular corrosion (ICC)is observed above the transverse fracture face that was caused by tensile testing. (16X Mag.) t ~,.-

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. [+.& vh.-. Mbtpu....- W.,. .a> -- s,ii: -..z. ^g n . :,-:0.q-5:w. c.0% p3 C5'QW %$khk'hb;hhE 5,[5(QL .1-k#ity:. i -'g .l I.' p Tensile Fracture Face T- .,...p '..d's Figure 9b Radial metallographic section showing the TSP 2 region of Tube R28C42 at a depth of 34% below the OD surface. Only axial intergranular corrosion is observed at the same location shown in Figure 9a. (16X Mag.) -}}

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