ML20044F913
| ML20044F913 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/30/1992 |
| From: | ROCKWELL INTERNATIONAL CORP. |
| To: | |
| Shared Package | |
| ML20044F896 | List: |
| References | |
| EPRI-TR-101427, EPRI-TR-101427-V03, EPRI-TR-101427-V3, NUDOCS 9306010189 | |
| Download: ML20044F913 (70) | |
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EPRI TR-101427 W5
. Nuclear steam generators Volume 3 Intergranular corrosion Project S413-04 lectric Power Intergranular stress corrosion cracking Final Report lesearch Institute inconel alloys November 1992 3
Examination of Trojan Steam Generator Tubes M
Volume 3: Rockwell, Auger, and XPS Analyses Prepared by ROCKWELL INTERNATIONAL, Thousand Oaks, California b
EPRI f
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9306010189 930208
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PDR ADOCK 05000344 P
PDR E
REPORT
SUMMARY
Examination of Trojan Steam Generator Tubes Volumes 1-3 l
Examination of 10 tubes removed from Trojan steam generators characterized the depth and type of defects associated with eddy-current signals originating at the tube support plate (TSP) locations.
The TSP indications were associated with 49-89% through-wall l
secondary-side intergranular degradation confined within the support.
Burst pressures of these degraded TSP locations exceeded regulatory requirements.
i BACKGROUND The Trojan nuclear power plant is a Westinghouse-designed INTEREST CATEGORIES four-loop PWR that began commercial operation in 1976. Secondary-side-initiated pitting attack of steam generator tubing was identified in 1986. Plant changes-such as discontinued condensate polisher operation and increased steam genera-Stearn generator reliability tot blowdown-reduced the ingress of copper, chloride, and sulfur impurities h!uclear plant life extension influencing the acid-driven pitting degradation. In addition, blowdown water was Nuclear plant Operations treated with a deep-bed demineralizer and returned to the system; secondary and maintenance water pH was raised from 8.5 to 9.2. Secondary-side axial-crack-like eddy-current indications at TSP intersections were first detected in 1988. The number of indica-KEYWORDS tions increased. In 1991, a total of 10 tubes, including 24 TSP intersections, were removed for destructive examination.
Nuclear Steam generators Intergranular Corr 0Sion OBJECTIVES To characterize inside diameter (ID)-initiated defects at the tube-Intergranular Stress sheet top; to define the relationship between defects and tube properties; to char-Corrosion Cracking acterize outside diameter (OD) degradation and determine the burst pressures of Inconel alloys defects at TSP locations; to evaluate the effectiveness of eddy-current field test techniques; and to characterize deposits.
APPROACH The project team characterized the pulled tubes by visual and dimensional examination, double and single-wall radiography, burst testing, frac-tography, metallography, X-ray photoelectron spectroscopy (XPS), and Auger analysis.
RESULTS Investigations revealed the following:
No ID-initiated defects were observed in the tube samples examined.
. Burst pressures of degraded TSP regions exceeded the NRC requirement of three times the normal operating primary-to-secondary water pressure differential.
Eddy-current testing provided a relatively good indication of burst capability but did not correlate to the depth of degradation.
. Metallography within the TSP region showed OD axialintergranular cracks ranging between 49-98% through the wall with patches of intergranular attack.
Up to 0.23 mm of black, hard, tenacious deposits covered the free surface of the tubes. On the basis of secondary water chemistry and nickel / chromium ratios at crack tips, corrosion was likely due to the concentration of caustic species in TSP crevices.
EPRI TR-101427s Vols.1-3 Electric Power Research Institute
Volume 1 contains ths results of destructive examination. Volume 2 i
includes the appendixes for the destructive examination. Volume 3 describes the results of the Auger and XPS analyses.
l EPRI PERSPECTIVE Though the conclusion that a caustic environment was responsible for degradation is not without uncertainties, it received support from MULTEO (EPRI report NP 5561-CCML) and hideout return studies that also suggest alkaline-forming tendencies. The alkaline-forming tendency likely originated after the 1987-1988 change in plant operation to remove acid-forming species responsible for pitting attack. The degrada-tion occurred during the 1988-1991 period, despite boric acid addition begun in August 1989. It is not clear when initiation occurred-whether during the transitional period from acid-forming to alkaline-forming chemistry or during the alkaline period of operation only. Both chemistries have been shown to cause attack in laboratory tests. The fact that detect-able cracks appeared during boric acid operation suggests initiation under acid conditions because boric acid is believed to more effectively -
inhibit initiation than growth under alkaline chemistries. If cations such as sodium are not balanced by anions such as chloride, the product will be an alkaline-producing sodium hydroxide. The need to maintain this bal-ance by molar ratio control criteria is the subject of the Trojan plant's cut-rent water chemistry program and a revision to EPRI's Secondary Water Chemistry Guidelines (report NP-6239).
PROJECTS RPS413-02, RPS413-04 Project Manager: Allan R. McIlree Nuclear Power Division Contractors: ABB Combustion Engineering; Rockwell International For further information on EPRI research programs, call EPRI Technical Information Specialists (415) 855-2411.
Y
Examination of Trojan Steam Generator Tubes Volume 3: Rockwell, Auger, and XPS Analyses TR 101427, Volume 3 Research Project S413-04 Final Report, November 1992 Prepared by ROCKWELL INTERNATIONAL Science Center 1049 Camino Dos Rios Thousand Oaks, California 91358 Prepared for Portland General Electric Trojan Nuclear Plant 71760 Columbia River Highway Rainier, Oregon 97048 Electric Power Research Institute 3412 Hillview Avenue Palo Alto, California 94304 EPRI Project Manager A. R. McIlree Steam Generator Reliability Program Nuclear Power Division l
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Electnc Power Research Institute and EPRI are registered service marks of Electnc Power Research Institute. Inc Copynght 1992 Electoc Power Research Institute. Inc. All nghts reserved
EPRI Lic:nsed M:t:ri:I ABSTRACT Corrosion products were examined on tubing from tube / tube support plate intersections from steam generators C and D of the Trojan Nuclear Station.
Tubes R29C70, R30C64, R16C74, R20C66 and R12C70 were removed in 1991 after eddy current indications of IGSCC.
The in-depth composition profiles of the films on the OD and fracture faces of R29C70, R30C64, R16C74, and R12C70 had Cr levels less than that in the alloy when compared with Fe and N1.
Laboratory data and thermodynamic considerations, while somewhat limited in scope, suggest that these low Cr levels correlate with a highly alkaline or caustic environment.
Tube R20C66, which was plugged in 1990 but removed in 1991, had Cr levels in the corrosien products which indicate a neutral or alkaline crevice; however, the data from R20066 had considerably more scatter than that from the other tubes.
Films of corrosion products were also examined on Tube R25C58, which was removed in 1986.
This tube had a film chemistry which suggested the crevice pH was less than th'at experienced by the tubes removed in 1991.
No cracks were present in R25C58.
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CONTENTS l
Section Pace i
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INTRODUCTION 1-1 l
2 METHODOLOGY 2-1 3
RESULTS 3-1 l
4 DISCUSSION 4-1 5
CONCLUSIONS 5-1 6
REFERENCES 6-1 1
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ILLUSTRATIONS Figure Pace 2-1 Optical Photomicrographs of Tube R25C58 Showing (a) Cross Sectional View and (b) View of OD (4X) 2-2 3-1 SEM Photomicrograph of the Area of Tube R25C58 Analyzed by AES 3-3 3 '<
Auger In-depth Composition Profile of the Film on the OD of Tube R25C58 at the Tube / tube Support Plate Intersection Showing the Alloy Metals Normalized to 1004 3-3 3-3 As-received Section of Tube R29C70 Showing the Points A-L Where an Analysis of the Surface was Made by AES 3-4 3-4 SEM Photomicrograph of the Crack Which was Analyzed in Tube R29C70 3-6 3-5 SEM Photomicrograph of the Fracture Face of the Crack Shown in Figure 3-4 (Tube R29C70) with the Areas Analyzed Indicated 3-6 3-6 SEM Photomicrograph of the Center of Region A Near the Crack Mouth in Figure 3-5 (Tube R2 9C70) 2-7 3-7 SEM Photomicrograph of the Center of Region B in Figure 3-5 (Tube R29C70) 3-7 3-8 SEM Photomicrograph of the Center of Region C in Figures 3-5 (Tube R29C70) 3-8 3-9 SEM Photomicrograph of the Center of Region D Near the Crack Tip in Figure 3-5 (Tube R29C70) 3-8 3-10 Optical Photomicrograph of As-Received Section of Tube R30C64.
The Arrows Indicate The Location of the Crack Analyzed 3-13 3-11 SEM Photomicrograph Showing the Fracture Face of the Crack Analyzed in Tube R30C64, Where Regions A,
B, C are the Individual Grains Analyzed 3-14 vii
EPRILic:nsed M:t:ri:I Figure Page 3-12 SEM Photomicrographs Showing the Grains Analyzed on the Fracture Face of Tube R30C64 in (a) Regions A and B (b) Region C 3-15 3-13 Optical Photomicrograph (6X) cf the Section of Tubing Form Tube R16C74 Received Showing the. Crack Examined and the Initial Cut Made to Extract a Section for Analysis 3-17 3-14 SEM Photomicrograph of the Section of Tube R16C74 i
Received Showing the Extensive IGA 3-18 l
l 3-15 SEM Photomicrograph of the Fracture Face of R16C74 l
Examined Showing the Grains Analyzed 3-19 i
j 3-16 SEM Photomicrograph of a Typical Region Near the OD on the Fracture Face of R16C74 Examined 3-19 3-17 SEM Photomicrograph (10X) of As-Received Section of Tubing R12C70 showing the OD surface 3-22 3-18 SEM Photomicrograph of As-received Section of Tubing R12C70 Showing the Fracture Face Analyzed 3-23 3-19 SEM Photomicrograph Showing the Grains Profiled on the Fracture Face of R12C70 3-23 3-20 SEM Photomicrograph Showing Typical Region of the Fracture Face of R12C70 in High Magnification 3-24 I
l 3-21 Optical Photomicrograph (6X) of As-Received l
Section of Tubing from R20C66.
The Cut in the l
Section was Made After Receipt from ABB/ Combustion Engineering 3-26 3-22 SEM Photomicrograph of the OD of Tube R20C66 Showing the Shallow IGA 3-27 1
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i Figure f ag.E 3-23 SEM Photomicrograph Showing the Grains Analyzed on the Fracture Face of a Crack in Tube R20C66, Where A is near the Crack Mouth, D is Near the Crack Tip and Grains B and C are Between the Crack Mouth and Crack Tip 3-30 3-24 SEM Photomicrograph of As-received Section from Tube R12C8 3-35 3-25 SEM Photomicrograph of the Fracture Face Analyzed
.from Tube R12C8 3-36 4-1 Potential-pH Diagram for the Fe-water System (at i
288 C) with Dissolved Species Activities of 10-3 [1]
4-2 4-2 Potential-pH Diagram for the'Cr-water System (at 288 C) with Dissolved Species Activities of 10-3 [3]
4_3 4-3 Potential-pH Diagram for the Ni-water System (at 2 8 8*C ) with Dissolved Species Activities of 10-3 [3) 4_4 4-4 Auger In-Depth Composition Profile for Alloy 600 Which was Exposed to 50% NaOH at 320 C 4-5 4-5 Auger In-Depth Composition Profile for Alloy 600 Which Had Been Exposed to 50% NaOH at 320 C While Polarized 150 mV Above the Corrosion Potential, E corr 4-5 4
4-6 Change in Fe, Cr, and Ni Composition of the Surface Film on Alloy 600 After Exposure to H SO /Na2SO /NaOH Solutions of Varying pH's 2
4 4
(280 C) [2]
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EPRI Lic:n:ed Mat: rial TABLES Table Pace 2-1 List of Tubes and Tube Support Plate (TSP) Inter-section Where the Tubing Examined Was Removed 2-1 3-1 Auger In-Depth Composition Profile from a Region on the OD of Tube R25C58 3-2 3-2 Auger Analysis of Points Indicated as E-S on the Surface of Tube R29C70 3-4 3-3 Auger In-Depth Composition Profile from the Region Centered at Point D on the Surface of Tube R29070 (Figure 3-3) 3-5 3-4 Auger In-Depth Composition Profile of Region A (Crack Mouth) in Figure 3-5 (Tube R29070) 3-9 3-5 Auger In-Depth Composition Profile of Region B on the Fracture Face in Figure 3-5 (Tube R29C70) 3-10 3-6 Auger In-Depth Composition Profile of Region C on the Fracture Face in Figure 3-6 (Tube R29C70) 3-11 3-7 Auger In-Depth Composition Profile of Region D (Crack Tip) in Figure 3-7 (Tube R29C70) 3-12 I
3-8 Auger In-Depth Composition Profile on a Region on the OD of Tube R30C64 3-14 3-9 Auger In-Depth Composition Profile of Region A (Crack Mouth) on Fracture Face in Tube R30C64 Shown in Figure 3-12(a) 3-16 3-10 Auger In-Depth Composition Profile of Region B (Mid-Point on Fracture Face in Tube R30C64) in Figure 3-12 (a) 3-16 3-11 Auger In-Depth Composition Profile of Region C (Crack Tip) on Fracture Face in Tube R30C64 Shown in Figure 3-12 (b) 3-16 3-12 Auger In-Depth Profile of a Region on the OD of Tube R16C74 3-1B xi
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3-13 Auger In-Depth Composition Profile of Region A (Crack Mouth) on Fracture Face of Tube R16C74 Shown in Figure 3-15 3-20 3-14 Auger In-Depth Composition Profile of Region B (Mid-Point on Fracture Face of Tube R16C74) in Figure 3-15 3-20 3-15 Auger In-Depth Combustion Profile of Region C (Crack Tip) on Fracture Face of Tube R16C74 Shown in Figure 3-15 3-21 3-16 Auger In-Depth Composition Profile of a Region on the OD of Tube R12C70 3-22 3-17 Auger In-Depth Composition Profile of Region A (Crack Mouth) on Fracture Face of Tube R12C70 Shown in Figure 3-19 3-25 3-18 Auger In-Depth Composition Profile of Region B (Crack Tip) on Fracture Face of Tube R12C70 Shown in Figure 3-19 3-25 3-19 Auger In-Depth Composition Profile of the film on the OD of Tube R20C66 Between IGA 3-27 3-20 Auger In Depth Composition Profile of a Region Inside a Crack Caused by IGA (Tube R20C66) 3-28 3-21 Auger In-Depth Composition Profile of Grain A (Crack Mouth) on Fracture Face of Tube R20C66 in Figure 3-23 3-31 l
3-22 Auger In-Depth Composition Profile of Grain B in Figure 3-23 (Tube R20C66) 3-32 3-23 Auger In-Depth Composition Profile of Grain C in Figure 3-23 (Tube R20C66) 3-33 3-24 Auger In-Depth Composition Profile of Grain D (Crack Tip) on Fracture Face of Tube R20C66 in Figure 3-23 3-34 l
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3-25 Auger In-Depth Composition Profile of the CD of Tube R12C8 3-35 3-26 Auger In-Depth Composition Profile of the Fracture Face of Tube R12C8 3-36 Xiii
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EPRI Lic:nsed M;t:ri:I section 1 INTRODUCTION The chemistry of the film, or corrosion products, on the surface of a metal or alloy is determined by the environment to which a metal or alloy was exposed. As the pH, temperature, composition and/or oxidizing conditions of an aqueous environment change, different reaction products become thermodynamically stable.
Laboratory results obtained from an EPRI funded program at Rockwall [1] and subsequent Japanese work [2] demonstrated that the concentration of alloy metals in the corrosion products on alloy 600 change in a predictable manner with pH.
Previous work has used the composition of the corrosion products on the surface of alloy 600 tubing to identify the local crevice environment in a steam generator which may have caused intergranular stress corrosion cracking (IGSCC) (,lml].
This report presents results of an analysis of the corrosion products on sections of alloy 600 tubing from the tube / tube support plate crevices in the Trojan Nuclear Plant.
This evaluation has been used to hypothesire the crevice chemistry.
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EPRILicsnsed Material Section 2 METHODOLOGY The sections of tubing analyzed were received from ABB/ Combustion Engineering.
All sections contained a tube / tube support plate intersection zone.
Table 2-1 ident'ifies the tubes analyzed.
This 2
table also indicates the tube / tube' support. plate intersection, the steam generator, the year in which the tube.was plugged, and when the tube was removed.
Tube R25C58 was received.in a metallographic mount.
Figure 2-1 shows a-cross sectional and OD view after this tube was broken-from the-mount.
The as-received
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condition of the other samples were sections of tubing approximately 1 cm x 1 cm.
Each of the small sections received.
had one or more axial cracks which were clearly visible under a low power microscope.
All the 1 cm x 1 cm tube sections received, except that from tube R12C70, had been cut from tubes after they had been burst tested.
A burst test was not performed on tube R12C70 prior to sectioning.
Table 2-1 LIST OF TUBES AND TUBE SUPPORT PLATE (TSP)
INTERSECTION WHERE THE TUBING EXAMINED WAS REMOVED TUBE TSP S/G YEAR PLUGGED REMCNED-R25C58 1
C Not Plugged 1986-R29C70 1
C 1991 5/91 R30C64 1
C 1991 9/91-10/91 R16C74 2
D 1991
-11/91 R12C70 2
C 1991 11/91 R20066 1-D 1990 11/91 R12C8 1
D 1989 5/91 2-1
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Figure 2-1.
Optical Photomicrographs of Tube R25C58 Showing (a)
Cross Sectional View and (b) View of OD Two surface analysis techniques were used to determine the fracture face and OD chemistries, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS)
AES was used to obtain in-depth, elemental composition profiles of the films by i
sequentially sputtering by argon ion bombardment and performing l
Auger analysis.
A Perkin-Elmer PHI Model 590 Scanning Auger Microprobe was used for the Auger examination.
The analysis was performed using an electron beam excitation voltage of 3 KV, charging was observed at higher voltages in some cases, and a 6 eV modulation voltage.
The OD was analyzed with the electron beam rastered 30 pm x 30 pm.
Individual grains were analyzed on the fracture face in all sections of tubing, except that from tube R29C70, with a stationary electron beam defocused to a diameter of approximately 10 m.
The electron beam was rastered 100 pm x 100 pm during the analysis of the fracture face of R29C70 because the large density of deposits made the fracture face composition nonuniform from grain to grain.
Sputtering was 2-2 f
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performed with a 5 KV argon ion beam rastered over an area 2.7 mm x 4 mm, which gave a sputtering rate of approximately SA/s.
X-ray photoelectron spectroscopy (XPS) was used for compound identification without sputtering since ion bombardment has been found to change the valence state and chemical state of surface species in some cases.
A Perkin-Elmer, PHI Model 548 XPS spectrometer was used for this analysis.
The excitation source for the photoelectrons was the MgKa line.
The diameter of the analysis area was several hundred micrometers.
2-3
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EPRI Lic:n:ed M:lirl:1 Section 3 RESULTS AES Results Table 3-1 shows the Auger in-depth profile of the OD of R25C58.
Since this sample had been removed from a metallographic mount, care was-taken to select sections of the OD for analysis where the appearance of the oxide and inspection of the sections of mount indicated that the scale was undisturbed during removal.
This section of tubing was examined optically and in the SEM for cracks.
None were found.
Figure 3-1 is an SEM photomicrograph of the area analyzed.
An area 30 pm x 30 pm was profiled in the center of Figure 3-1.
Table 3-1 is the in-depth composition profile obtained from this analysis area.
The table is formatted such that the last column to the right gives the depth sputtered, the next three columns to the left give the relative atomic percent of the alloy metals normalized so that they add to 1001, and the remaining columns give the atomic percents of all the detected species, which originated from the secondary water.
The oxide was sputtered to a depth of 4 pm.
Zine was present in the oxide at relatively high concentrations, particularly in the first 5000A.
Carbon was high near the surface, but quickly decreased to low levels during sputtering after removing a few hundred Angstroms of film.
Examining the relative amounts of Cr, Fe, and Ni, the Fe concentration is approximately three times that of the sum of Cr and Ni for the first 600A.
Iron then decreases in concentration with depth with a corresponding increase in Ni.
1 This is more clearly indicated in Figure 3-2, which shows graphically the relative changes in the alloy metals.
The concentration of chromium in the oxide is approximately that in 3-1
EPRI Licen:ed M:t:rlII the alloy for the first 1000A in depth, after which there is a layer approximately 1 pm in width where it is enriched.
Table 3-1 AUGER IN-DEPTH COMPOSITION PROFILE FROM A REGION ON THE OD OF TUBE R25C58 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni C
01 Zn Cr Fe Ni A
41.1 3.8 15.7 2.8 17.3 0.3 19.0 17.0 70.5 12.5 0
44.5 5.1 20.8 2.9 8.0 0.2 18.4 17.8 72.3 10.0 100 44.7 5.8 22.8 2.7 6.5 0.2 17.1 18.6 72.7 8.7 250 46.3 6.3 23.2 3.7 3.6 0.0 16.9 18.8 69.9 11.3 400 47.6 6.7 25.0 3.2 2.5 0.0 14.9 19.2 71.5 9.3 600 46.4 8.3 26.6 4.9 1.2 0.0 12.6 20.9 66.8 12.3 1600 45.8 11.5 25.4 6.9 0.6 0.2 9.8 26.2 58.1 15.7 3200 42.1 12.9 22.5 14.1 0.6 0.0 7.8 26.1 45.4 28.5 6400 32.0 13.2 18.2 30.4 0.7 0.0 5.5 21.3 29.5 49.2 12800 21.0 13.2 13.8 47.9 1.1 0.0 3.1 17.6 18.4 64.0 25600 24.7 11.9 13.5 44.5 1.6 0.0 3.7 17.0 19.3 63.6 35000 19.8 13.4 15.7 50.3 0.7 0.0 0.0 16.9 19.8 63.3 40000 Figure 3-3 shows the as-received section of tube R29C70.
An Auger analysis was performed before sputtering at the points indicated by letters A through L.
The results from the points (beam size approximately 1 pm in diameter) which did not charge are given in Table 3-2.
No Cr was observed at five of the nine points, two points had Cr levels, relative to Fe and Ni, considerably below that in the alloy.
At two points, Ni was the only alloy metal detected; whereas, all other points were substantially enriched in Fe relative to that in the alloy.
Of the impurities found Si, F and Zn were in the highest concentrations.
The electron beam was rastered to give an analysis area of approximately 30 pm x 30 pm, centered at area D, to obtain the in-depth profile in Table 3-3.
Examining the relative amounts of Fe, Cr, and Ni, the concentration of Cr was approximately the same level as in the alloy, and Fe was three to four times higher in concentration'than 3-2
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1 10 100 1000 10000 100000 jl DEPTH SPLJTTERED(A)
)
Figure 3-2.
Auger In-depth Composition Profile of the j
Film on the OD of Tube R25C58 at the Tube / tube Support l
Plate Intersection Showing the Alloy Metals Normalized to 100%
3-3
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3 A
Bs C
i D
l E
I F
f G
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H I
J K
L Imm a
f Figure 3-3.
As-received Section of Tube R29C70 Showing the Points A-L Where an Analysis of the Surface was Made by AES P
I Table 3-2 AUGER ANALYSIS OF POINTS INDICATED AS E-S ON THE SURFACE OF TUBE R29C70 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Si Qi C
Cu Zn F
Cr Fe Ni UDCATON 61.6 0.0 0.0 3.6 11.6 2.2 13.6 0.0 0.0 7.4 0.0 0.0 100.0 A
36.5 0.0 3.4 11.0 3.2 0.0 37.9 0.0 0.0 8.0 0.0 23.8 76.2 B
50.8 0.0 0.0 4.3 7.2 1.2 26.9 0.0 3.3 6.2 0.0 0.0 100.0 C
32.7 0.0 2.6 2.0 19.5 0.8 31.6 2.3 2.2 6.4 0.0 56.9 43.1 D
23.2 4.9 16.1 28.5 2.2 1.0 17.2 1.9 5.0 0.0 9.9 32.5 57.6 E
35.3 0.0 0.0 2.3 6.1 0.0 40.7 1.8 6.5 7.3 0.0 0.0 100.0 F
47.8 2.5 4.7 4.9 15.5 3.2 12.5 2.1 3.0 3.7 20.6 39.0 40.4 G
33.0 5.6 18.8 15.1 7.5 1.8 13.4 0.0 4.9 0.0 14.2 47.6 38.2 H
40.4 3.8 10.6 7.7 10.5 6.6 11.9 2.0 2.5 4.0 17.4 48.1 34.6 1
47.6 4.6 7.3 13.1 11.7 0.9 12.5 2.3 0.0 0.0 18.4 29.3 52.3 J
57.1 12.3 0.0 11.9 0.0 3.3 3.9 4.0 0.0 7.5 50.8 0.0 49.2 K
i i
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Table 3-3
)
AUGER IN-DEPTH COMPOSITION PROFILE FROM THE REGION 1
CENTERED AT POINT D ON THE SURFACE OF TUBE R29C70 (FIGURE 3-3) l I
Atomic Percents Normalized Atomic Percents A
i O
Cr Fe Ni Cu Si Qa C
Cr Fe Ni i
i i
(
47.5 4.6 7.3 13.1 2.3 11.7 1.0 12.5 18.4 29.3 52.3 0
[
39.2 4.5 7.2 21.1 5.5 8.3 1.2 13.1 13.8 21.9 64.4 800 l
34.3 6.7 9.1 26.8 4.1 6.9 1.7 10.4 15.7 21.4 62.9 1000 l
32.6 8.0 9.1 29.3 3.0 5.6 1.9 10.5 _17.3 19.5 63.1 1200 j
30.7 8.8 9.3 31.3 3.5 4.7 2.2 9.4 17.8 18.9 63.3 1400 29.2 8.9 10.1 33.3 3.2 4.1 2.4 8.8 17.0 19.4 63.6 1600 i
i 27.7 10.6 9.6 35.1 3.1 3.7 2.2 7.9 19.2 17.4 63.4 2000 i
26.5 11.2 10.1 38.2 2.5 3.0 2.0 6.4 18.8 17.0 64.2 2600 26.7 12.5 10.0 39.8 2.2 2.1 1.6 5.0 20.0 16.1 63.9 3400 27.3 13.4 9.9 40.5 2.3 1.4 1.5 3.7 21.1 15.5 63.5 4600 1
26.2 14.3 10.0 42.7 2.2 0.6 1.3 2.7 21.3 14.9 63.7 6000 26.0 14.0 9.0 45.5 1.5 0.6 1.2 2.2 20.4 13.2 66.4 9000 i
25.2 14.1 8.8 47.6 1.1 0.3 0.8 2.1 20.0 12.5 67.5 15000 j
j 24.2 14.7 9.7 47.4 1.7 0.2 0.5 1.6 20.5 13.5 66.1 17000 1
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l that found in Alloy 600.
Both Cu and Si were in high f
concentrations.
l i
The fracture face of a totally intergranular crack approximately i
60% through-wall, shown in Figure 3-4, was examined.
Four areas I
designated A, B,
C, and D were analyzed as indicated in the SEM l
i photomicrograph in Figure 3-5.
The beam was rastered so that l
4 j
areas 100 pm x 100 pm were analyzed.
This approach differs frcm j
all other fracture face examinations in which individual grains
)
were examined.
Figures 3-6 through 3-9 are SEM-photomicrographs
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of the center of the analysis areas.
There are numerous deposits j.
on the grains, the density of which decreases progressing from the l
crack mouth to the crack tip.
The Auger in-depth profiles are given in Tables 3-4 through 3-7.
Silicon was found in l
concentrations as high as 8.0 a/o at the crack mouth (area A) and i
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SEM Photomicrograph of the Crack Which Was j
Analyzed in Tube R29C70 t
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SEM Photomicrograph of the Fracture Face of the Crack Shown in Figure 3-4 (Tube R29C70) with the Areas Analyzed Indicated l
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SEM Photomicrograph of the Center of Region A l
Near the Crack Mouth in Figure 3-5 (Tube R29C70) se, d
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SEM Photomicrograph of the Center of Region B in Figure 3-5 (Tube R29C70) 3-7
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SEM Photomicrograph of the Center of Region C in Figure 3-5 (Tube R29C70) l
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Figure 3-9.
SEM Photomicrograph of the Center of Region D Near the Crack Tip in Figure 3-5 (Tube R29C70) i 3-8 L
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Table 3-4 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION A (CRACK HOUTH)
IN FIGURE 3-5 (TUBE R29C70)
Atomic Percents Normalized Atomic Percents
'i O
Cr Fe Ni
- Si C
F
.Cr Fe Ni A
31.4 1.8 0.0 21.8 5.6 15.7 2.2 7.8 0.0 92.2 0
33.8 19 0.0 23.1 6.4 10.7 1.7 7.5 0.0 92.5 50 33.3 1.7 0.0 24.8 7.1 8.7 1.5 6.4 0.0~
93.6 100 31.5 1.9 3.2 28.4 7.0 6.9-0.0 5.7 9.5 84.8 200' 30.7 2.0 3.2 30.3 7.2 5.8 0.0 5.6 9.0 85.4 300 31.2 2.0 3.3 30.7 7.2 5.1 0.0 5.7 9.1 85.3
'400 s
30.1 2.0 2.7 31.4 8.0 4.3 0.0 5.7-7.4 86.9 500 30.0 2.3 3.4 33.1 6.7 4.4 0.0 5.9 8.7 85.4 700 27.4 3.6. 3.4 39.4 6.1 3.0 0.0 7.7 7.4-84.9 1650 25.1 4.9 3.7 43.2 5.6 2.7 0.0 9.5
' 7.1 -
83.5 3000-23.8 5.7 4.4 45.9 5.4 2.2 0.0 10.2 7.8 82.0 5000 21.9 6.6 5.1 49.7 5.2 1.8 0.0 10.8 8.3 80.9 7500 i
20.6 7.6 6.9 49.9 4.9 1.5 0.0 '1i 8 10.7 77.5 10000 16.8 9.2 7.0 56.9 3.5 1.6 0.0 12.6 9.5 77.8 20000 13.7 10.4 7.7 60.4 2.3 1.9 0.0 13.3 9.8 -76.9
'30000 12.5 10.4 8.3 62.0 1.6
- 2. 7 0.0 12.9 10.3 76.8 40000 11.3 10.9 8.4 63.8 11 2.6 0.0 13.1 10.1 76.8 50000 10.0 11.2 8.1 66.4 0.5 2.1 0.0 13.1 9.5 77.4 -
60000 p
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Table 3-5 AUGER IN-DEPTH COMPOSITION PROFILE OF - REGION B j
ON THE FRACTURE FACE IN FIGURE 3-5 (TUBE R29C70)
Atomic Percents Normalized Atomic Percents O
Cr Fe Ni F
Si C
Cr Fe Ni A
36.8 3.2 0.0 30.0 4.1 1.3 24.6 9.6 0.0 90.4 0
39.3 4.0 0.0 34.3 2.5 1.9 18.0 10.4 0.0 89.6 50 40.0
- 3. 7.
0.0 37.0 2.1 2.4 14.7 9.0 0.0 91.0 100' 31.5 3.4 0.0 51.8 1.2 2.1 10.0 6.2 0.0 93.8 200 38.4 4.2 1.9 41.0 1.6 2.5 10.4 8.9 41 87.0 300 36.7 4.2 3.9 42.9 1.2 2.4 8.7 8.3 7.6 84.1 400 36.4 4.1 4.1 42.7 1.6 3.1 8.2 8.0 8.0 84.0 500 34.3 6.2 4.1 45.7 1.6 2.6' 5.6 11.1 7.3 81.6-700 29.7 5.9
.4.3 52.1 0.5 2.4 5.2 9.4 6.8 83.7 1650 24.8 9.2 5.0 54.0 0.0 2.3 4.6 13.5 7.3 79.1 3000 23.3 10.3 7.4 53.1 0.0 2.5 3.4 14.6 10.5-75.0 5000 20.1 9.5 6.0 59.1 0.0 2.3 3.1 12.7.
8.0 79.3 7500 17.9 12.1 7.0 57.7 0.0 2'2 3.1 15.8 9.1 75.-1 1000 14.6 14.3 7.2 59.8 0.0 1.6 2.5 17.5 8.9 73.6 20000 11.9 11.2 7.7 64.7 0.0 0.8 3.7 13.4 9.2 77.5 30000 10.8 11.4 7.6 64.7 0.0 0.3 5.3 13.6 9.0 77.4 40000 10.0 11.3 8.3 66.1 0.0 0.2 4.2 13.2 9.6 77.2 50000 9.4 10.7 8.4 67.4 0.0 0.1 3.9 12.4 9.7 77.9 60000 9
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Table 3-6 AUGER IN-DEPTH' COMPOSITION PROFILE OF REGION C l
ON THE FRACTURE -FACE IN FIGURE 3-6 (TUBE R29C70) l i
Atomic Percents Normalized Atomic j
Percents l
O Cr Fe Ni F
Si C
Cr Fe Ni A
j 32.0 3.1 0.0 34.3 4.6 0.0 26.1 8.2 0.0 91.8.-
0 i
33.0 3,4 0.0 38.5 3.7 0.0 -
21.4 8.1-0.0 91.9 50~
33.5 4.0 0.0 40.8 2.6 0.0 19.1 9.0 0,0 91.0 100.
33.3 4.2 0.0 44.3 2.3 0.0
-16.0 8.6 0.0 91.4 200
' 12.7 8.4 0.0 91.6 300:
33.4 4.3 0.0 47.6 1.9 0.0 32.5 4.5 0.0 50.0 1.9 0.0 11.1 8.3 0.0 91.7 400 j
30.5 4.6 3.6 48.9 1.8 0.0 10.6 8.0 6.4 85.6 500 29.8 4.7 3.6 52.1 0.8 0.0 9.0 7.8 6.0 86.2 700 23.5 6.6 4.5 58.6 0.5 0.0 6.3 9.4 6.5 84.1 1650
]
18.9 8.9 6.6 60.8 0.2 0.0 4.5 11.7 8.6 79.7 3000 16.8 9.7 6.8 62.9 0.0 0.0 3.9 12.2 8.5 79.3 6000 l
14.4 10.6 6.9 64.9 0.0 0.0 3.1 12.9 8.4 78.7 9000' 13.4~ 11.0 7.8 64.2 0.0 0.0 3.6 13.3 9.4 77.3
-10000 l
10.0 11.4 7.8 67.3 0.0 ' 0.0 3.5 13.2' 9.0 77.8 20000 8.3 10.6 8.0 68.7 0.0 0.0 4.3 12.2 9.1 78.7 30000 3
7.7 10.5 8.0 69.3 0.0 0.0 4.4 11.9 9.2 78.9 40000 i
7.5 10.0 8.4 69.8 0.0 0.0 4.4 11.3 9.5 79.2 50000 i
7.3 10.4 9.1 69.0 0.0 0.0 4.2 11.7 10.3 78.0 60000 3
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i Table 3-7 AUGER IN-DEPTH COMPOSITION PROFILE OF. REGION D i
(CRACK TIP)' IN FIGURE' 3-7 (TUBE R29C70)-
L l
Atomic Percents Normalized Atomic.
l Percents l
0 Cr Fe Ni F
Si C
Cr Fe Ni A'
l l
L 28.0 3.7 0.0 42.0 3.6
'O.0~
22.8 8.0 0.0 92.0 0
~ 50 l
26.3 4.7 5.2 51.3 1.6 0.0 11.0 7.7 8.4 83.9 19.1 5.3
.6.2 58.8 1.1 0.0 9.6 7.5 8.9 83.7 100 j
l 17.6 5.1 7.0 63.9- 0.0 0.0 6.4 6.8
-9.2 84.1-
.200 l
16.1 5.5 7.1 64.5 0.0 0.0 6.8 7.1 9.2 83.7 300-
'l i
15.5 5.9 - 6.8 65.9 0.0
.0.0 5.9 7.5 8.7 83.9-400' l
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15.1 5.6 7.5 64.7 0.0 0.0 71 7.2 9.7 83.1 500
.l 13.4 6.6 8.0 67.1 0.0 0.0 5.0 8.1 9.8 82.2.
700
.13.5 7.5 8.7 65.9 0.0 0.0 4.4 9.1 10.6'80.3' 1650 ~
l 9.4 9.2 8.7 69.9 0.0 0.0-2.8 10.5 9.9'79.6 3000 8.7 9.8 9.1 68.6-0.0 0.0 3.8 11.2 10.4 78.4 5000'-
6.5 10.0 8.9 71.8-0.0 0.0 ~
2.7 1 1 '.1.
9.8 79.1 7500 i
7.7 9.5 8.8 70.2 0.0 0.0 3.9 10.7.10.0'79.3. 10000 I
5.2 9.3 10.2 72.4 0.0' 'O.0-2.9 1'O.1-11'.1 78.8 20000-5.2 9.7 9.0 72.4 0.0 0.0 3.6 10.6.-
9.9 79.5 30000 I
3.6 10.1 10.1 73.6 0.0 0.0 2.5 10.8 10.7 78.5 '40000 i
3.6 9.8 9.7 74.7 0.0 0.0 2.1 10.4 10.3 79.3 50000 4.5 9.8 9.7 73.7 0.0 0.0.
2.3 10.5 10.4 79.1 60000 D
l at approximately 2 a/o in area B.
No Si was found in the other t
r two areas analyzed, which were closest to the crack tip.
Fluorine l
l was present up to almost 5 a/o in the outer several~hundred i
Angstroms of the film in all four areas analyzed on the fracture i
face.
Comparing the relative amounts of the alloy metals, all areas examined had much lover Cr levels than that in the alloy.
Iron was not present on the surface and in relative concentrations L
less than that in the alloy for several hundred Angstroms in the film.
Figure 3-10 shows the as-received condition of tube R30C64 with the crack which was opened for analysis indicated by arrows.
The-k 3-12 i
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l Figure 3-10.
Optical Photomicrograph of As-received I
Section of Tube R30C64.
The Arrows Indicate The Location of the Crack Analyzed l
I I
j in-depth composition analysis of the OD of this tube section is I
shown in Table 3-8.
The contaminating species in the oxide having the highest concentrations are Zn and Si neither of which decrease in concentration to approximately 2 pm in depth.
Comparing the relative amounts of alloy metals, the oxide is enriched in Fe and had no Cr until 3200A was sputtered.
The highest relative level pf Cr detected, in the 5 pm sputtered, was slightly more than half that in the alloy.
Figure 3-11 is an SEM photomicrograph of the totally intergranular fracture face profiled.
The grains profiled l
are shown in Figure 3-12.
Three grains were analyzed: near the i
crack mouth (A), approximately mid-way between the crack mouth and I
l crack tip (B), and near the crack tip (C).
There are a few highly dispersed deposits on the grains immediately adjacent to the OD 3-13 i
EPRI Licensed Material Table 3-8 AUGER IN-DEPTH COMPOSITION PROFILE ON A REGION ON THE OD OF TUBE R30C64 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Zn Si Qi C
Cr Fe Ni A
45.5 0.0 7.7 1.8 11.7 11.2 0.9 21.1 0.0 81.4 18.6 0
48.3 0.0 8.8 2.3 9.5 20.1 1.3 9.6 0.0 79.2 20.8 100 i
49.4 0.0 9.8 2.6 10.3 19.0 1.5 7.6 0.0 79.2 20.8 200 52.7 0.0 13.0 3.0 11.7 9.6-1.8 8.2 0.0 81.2 18.8 400 51.5 0.0 10.2 2.4 9.2 17.4 2.3 7.1 0.0 81.2 18.8 800 45.5 0.0 19.6 3.9 8.6 15.0 2.2 5.1 0.0 83.4 16.6 1600 45.5 0.0 21.8 3.9 7.2 14.9 2.7 4.0 0.0 85.0 15.0 3200 l
43.3 2.6 24.3 4.5 6.5 13.0 2.5 3.2 8.3 77.3 14.4 6400 j
43.8 3.5 24.1 6.7 5.4 11.9 2.3 2.4 10.2 70.3 19.5 12800 l
1 42.4 3.2 22.4 11.3 4.6 11.8 1.9 2.4 8.8 60.7 30.5 25000 j
40.8 5.3 20.1 19.7 2.7 8.5 1.6 1.4 11.7 44.6 43.6 50000 1
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Figure 3-11.
SEM Photomicrograph Showing the Fracture l
l Face of the Crack Analyzed in Tube R30C64, Where Regions l
A, B,
C are the Individual Grains Analyzed l
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SEM Photomicrographs Showing the Grains Analyzed on the Fracture Face of Tube R30C64 in (a) Regions A and B (b)
Region C l
l surface.
Otherwise, the fracture face is almost free of deposits.
f The profiles obtained for the grajns are given in Tables 3-9 l
through 3-11.
All three areas examined were almost identical in l
l composition.
Low amounts of Cu, and Ti were detected.
The 1
[
relative concentration of both Fe and Cr were slightly above those 1
l in the alloy.
l t
l l
i The as-received condition of R16C74 is shown in Figure 3-13.
The l
cut through the center of the specimen was made after the sample was received.
There were numerous shallow cracks on the surface (Figure 3-14).
The Auger in-depth profile from an area on the CD between cracks is shown in Table 3-12.
Aside from C, the impurities in the oxide in the highest concentrations are Si and S.
Copper and calcium are present at approximately I a/o.
The first 1600A of the oxide had no Cr.
After sputtering to a depth of 2.5 m Cr enriched to concentrations, relative to Fe and Ni, between 20 and 26 a/o.
Iron was considerably enriched relative to l
the percentage in the alloy.
3-15 l
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EPRILiccn:ed Mit:ri:I Table 3-9 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION ~ A (CRACK MOUTH)
ON FRACTURE FACE IN TUBE R30C64~ SHOWN IN. FIGURE 3-12 ( A) i l
Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Cu
'S C
TI Cr Fe Ni A
j t
31.3 12.6 6.4 39.2 0.0 0.0 8.8 1.7 21.7 11.0 67.4 0
29.6 11.8 6.5 35.8 0.7 0.2 14.2-1,3 21.8 12.1 66.2 100 29.1 12.0 6.4 38.0 1.3 0.2 12.0 1.1 21.3 11.3 67.4 200
[
t 28.6 11.4 6.7 40.6 0.6 0.2 11.0 - 0.9 19.4 11.4 69.2 400 23.0 12.4 7.1 48.0 0.0 0.1 8.6 0.7 18.4'.10.5 71.1 1000 l
13.0 14.0 7.4 54.9 0.0 01 9.9 0.8 18.3 9.7'72.0 2000 l
t 8.7 14.7 7.2 53.6 0.0 0.0 15.3 0.6 19.5 9.5 71.0 4000 I
i Table 3-10 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION B (MID-POINT ON FRACTURE FACE IN TUBE R30C64). IN FIGURE 3-12 (A)
Atomic Percents Normalized Atomic i
Percents l
O Cr Fe Ni Cu S
C TI Cr Fe Ni A
t i
34.6 13.9 4.8 32.2 0.9 0.8 11.7 1.1 27.4 9.3 63.3 0
41.0 14.5 4.1 33.1 0.0 0.5 5.7 1.1 28.0 7.9 64.1 100 33.6 13.1 5.6 40.4 1.1 0.5 4.9 - 0.8 22.1 9.5 68.4 200 I
35.3 10.5 6.8 42.6 0.0 0.3 3.8 0.6 17.5 11.4 71.1 400 l
18.7 14.7 6.4 49.8 0.4 0.4 8.4 1.2 20.7 9.1 70.2 1000-16.5 17.2 7.1 52.1 1.0 0.3 4.9 0.8 22.5 9.3 68.1 2000 i
12.6 17.1 7.6 56.9 0.0 0.0 4.8 1.1 20.9 9.3 69.8 4000 Table 3-11 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION C (CRACK TIP)
ON FRACTURE FACE IN TUBE R30C64 SHOWN IN FIGURE 3-12(B) i l
Atomic Percents Normalized Atomic l
Percents O
Cr Fe Ni S
C Ti Cr Fe Ni A
38.4 9.0 5.4 33.4 1.5 11.6 0.6 18.8 11.3 69.9 0
24.2 8.7 8.0 53.0 0.2 5.9 0.0 12.5 11.4 76.0 100 32.2
'9.2 6.7 46.9 0.4 4.2 0.5 1'4.6 10.7 74.7 200 32.6 9.2 7.5'46.4 0.2 3.7 0.4 14.5 11.9 73.6 400 l
20.3 11.3 6.9 51.8 0.2 8.6 0.9 16.2 9.8 74.0 1000 11.9 16.0 8.3 60.8 0.0 2.5 0.5 18.8 9.8 71.5 2000 t
14.4 15.1 7.4 58.9 0.0 3.7 0.5 18.5 9.1 72.4 4000 L
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Figure 3-13.
Optical Photomicrograph of the Section of Tubing Form Tube R16C74 Received Showing the Crack Examined and the Initial Cut Made to Extract a Section for Analysis The fracture face of a 400 pm deep crack in R16C74 analyzed is shown in Figure 3-15.
Three grains as shown were analyzed:
A, near the crack mouth, B,
near the center, and C near the crack tip.
A higher magnification SEM photomicrograph is shown in Figure 3-16.
The ruptured oxide film on the OD in the vicinity of the crack mouth is clearly visible in the photomicrograph.
All of the grains including those near the crack mouth are featureless and contain no deposits.
Tables 3-13 through 3-15 are the in-depth composition profiles of regions A, B,
and C respectively.
Major contaminants in the oxide are S, C 1, C,
Cu, 2n, and F.
These changed very little in concentration with depth for j
approximately 1.3 pm, 3000A, and 1000A of sputtering in regions A, l
B, and C respectively.
These species then decreased slowly with l
l t
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SEM Photomicrograph of the Section of Tube R16C74 Received Showing the Extensive IGA j
l Table 3-12 i
AUGER IN-DEPTH PROFILE OF A REGION ON THE i
j OD OF TUBE R16C74 i
Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Si S
C Ca Cu Cr Fe Ni A
16.6 0.0 7.6 6.9 2.8 3.9 60.6 0.0 1.7 0.0 52.4 47.6 0
20.8 0.0 7.7 12.3 5.3 4.7 47.1 0.6 1.5 0.0 38.5 61.5 200 l
l 35.8 0.0 5.3 13.3 8.4 3.9 31.3 0.7 1.3 0.0 28.7 71.3 400 1
29.9 0.0 8.9 18.3 13.5 3.4 23.5 1.2 1.4 0.0 32.8 67.2 800 32.2 0.0 9.520.515.1 2.7 17.3 1.4 1.3 0.0 31.8 68.2 1500 32.6 0.0 12.1 16.0 12.5 2.4 22.5 0.8 1.2 0.0 43.0 57.0 1600 32.3 3.6 13.1 16.3 11.9 2.3 18.5 0.8 1.2 11.0 39.6 49.4 3200 33.3 3.7 15.9 16.8 12.7 1.6 13.9 1.0 1.2 10.2 43.7 46.2 6400 33.8 7.1 17.1 17.4 10.8 1.1 10.3 1.0 1.3 17.0 41.2 41.8 12800 36.3 9.5 17.1 19.6 9.7 0.4 6.5 1.0 0.0 20.6 37.0 42.3 25600 41.2 11.6 17.8 23.2 0.0 0.0 5.2 1.0 0.0 22.0 33 8 44.1 36455 l
41.7 13.0 17.0 25.0 0.0 0.0 2.5 0.8 0.0 23.6 30.9 45.5 51200 l
40.6 12.7 17.2 25.1 0.0 0.0 3.5 0.9 0.0 23.2 31.2 45.6 70630 40.7 13.2 16.3 27.0 0.0 0.0 2.0 0.8 0.0 23.3 28.8 47.8 80000 38.0 14.2 13.5 28.8 3.1 0.0 1.8 0.5 0.0 25.1 23.8 51.0 100000 38.5 15.1 14.5 29.0 1.6 0.0 0.8 0.6 0.0 25.8 24.7 49.5 240000 l
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SEM Photomicrograph of the Fracture Face of R16C74 Examined Showing the Grains Analyzed t
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Figure 3-16.
SEM Photomicrograph of a Typical Region Near the OD on the Fracture Face of R16C74 Examined 3-19 j
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EPRI LicInIed Mat:rbl Table 3-13 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION A (CRACK MOUTH)
ON FRACTURE FACE' OF TUBE R16C74 SHOWN IN FIGURE 3-15 Atomic Percents Normalized Atomic Percents -
O Cr Fe Ni Si S
Cl C
QJ' Zn F-Cr Fe Ni A
l l
24.5 0.0 0.0 20.2 0.6 5.3 0.7 34.4 7.6 3.4 3.4 0.0 0.0 100.0 0
31.2 0.0 0.0 23.1 0.7 3.2 1.5 27.2 6.4 2.2 4.5 0.0 0.0 100.0 50 i
33.0 0.0 0.0 25.9 1.1 3.1 1.0 26.0 5.8 0.0 4.1 0.0 0.0 100.0 100
(
24.3 0.0 0.0 27.6 0.9 4.2 1.0 27.8 8.3 ' 2.1 3,8 0.0 0.0 100.0 20'0 32.9 0.0 0.0 27.2 1.4 3.4 0.5 23.4 6.2 1.7 3.3 0.0 0.0 100.0 400' 32.2 0.0 0.0 26.2 1.1 3.6 0.7 25.4 5.9-1.4 3.5 0.0 0.0 100.0 800 33.0 0.0 0.0 26.4 0.8 3.9 0.6 25.7 5.0 1.4 3.2 0.0 0.0 100.0 1600 I
32.3 0.0 0.0 27.8 1.6 4.4 0.6 22.6 6.1 1.6 3.0 0.0 0.0 100.0 3200 32.3 0.0 0.0 28.6 1.3 4.6 0.7 21.9 6.2 1.5 2.8 0.0 0.0 100.0 6400 22.6 8.5 7.3 31.5 0.3 2.5 0.5 19.0 4.1 1.2 2.5 17.9 15.5 66.6 12800 19.1 11.1 11.9 38.2 0.4 2.1 0.2 12.3 3.3 0.0 1.4 18.2 19.4.
62.4 20000 Table 3-14 1
AUGER IN-DEPTH COMPOSITION PROFILE OF REGION B (MID-POINT ON FRACTURE FACE OF TUBE R16C74)
IN FIGURE 3-15 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Si S
Cl C
0; Zn F
Cr Fe Ni A
l 30.0 2.5 0.0 26.8 1.4 4.6 0.7 28.4 0.8 1.8 2.9 8.4 0.0 91.6 0
29.5 3.5 0.0 26.9 1.3-5.0 0.7 28.3 0.9 1.7 2.3 11.5 0.0 88.5 50 30.1 3.2 0.0 26.9 1.8 5.2 0.6 27.0 0.8 2.4 2.1 10.5 0.0 89.5 100 30.7 3.2 0.0 27.4 1.8 5.3 0.7 25.8 0.7 2.1 2.3 10.5 0.0 89.5 200 32.8 2.8 0.0 27.5 2.2 5.8 0.9 22.0 0.6 2.5 2.9 9.3 0.0 90.7 400 32.2 3.8 0.0 31.0 2.4 6.6 0.4 17.4 1.6 2.5 2.1 10.9 0.0.89.1 800 30.2 4.3 0.0 32.2 1.7 5.9 0.6 21.8 0.0 1.8 1.4 11.8 0.0 88.2.
1600 26.2 6.1 0.0 38.4 1.3 5.5 0.4 17.4 1.0 2.4 1.3 13.8.
0.0 86.2 3200 22.5 9.6 0.0 42.6 0.9 4.9 0.4 16.2 0.9 1.2 0.8 18.4 0.0 81.6 6400 r
16.0 14.2 4.4 51.2 0.0 2.1 0.2 9.8 0.8 0.0 1.3 20.3 6.3 73.4 12800 10.7 16.0 6.4 59.4 0.0 0.7 0.2 6.2 0.0 0.0 0.4 19.6 7.8 72.6 20000 i
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additional sputtering.
All three regions analyzed were completely depleted of Fe near the surface ranging from approximately 100A in depth in region C to 7000A in regions B and A.
All three regions were depleted of Cr.
No Cr was detected in the first 6400A of the film sputtered in region A (The film was nickel oxide with the contaminants listed above).
In region B,.the Cr, relative to the 3-20 I
i
1 EPRILicin:ed M111ri11 other alloy metals, was approximately a factor of two below that in the alloy in the outer 800A of the film.
The Cr in region C, relative to the other alloy metals, was approximately 60; that in the alloy.
Table 3-15 AUGER IN-DEPTH COMPOSITION PROFILE OF. REGION C (CRACK TIP)
ON FRACTURE FACE OF TUBE R16C74 SHOWN IN FIGURE 3 Atomic Percents Normalized Atomic
)
Percent O
Cr N
Ni Si S
Cl C
F Cr R
Ni A
[
36.9 4.6 0.0 31.4 1.5 2.7 0.5 19.5' 2.8 12.9 0.0 87.1 0
38.4 4.6 0.0 36.2 1.6 3.8 0.4 13.0 2.1 11.2 0.0 88.8 25 38.1 6.0 0.0 37.0 1.6 3.7 0.3 11.6 1.7 13.9 0.0 86.1 50 i
36.0 6.5 1.4 38.6 1.4 3.5 0.2 11.1 1.4 13.9
.3. 0 83.1 100 33.1 7.6 2.6 43.5 1.0 2.6 0.3 8.5 0.8 14.1 4.9 81.1-200 24.6 8.6 4.7 51.6 0.0 2.0 0.2 7.6 0.6 13.3 7.3 79.5 400 l
20.9 10.4 5.3 55.9 0.2 1.5 0.2 5.1 0.3 14.5 7.4 78.0 800 16.5 12.3 6.2 58.2 0.3 1.6 0.0 4.9 0.0 16.0 8.0 75.9 1600 10.4 14.6 7.1 63.9 0.0 0.4 0.0 3.6 0.0.17.0 8.3 74.7 3200 t
10.3 15.7 7.5 61.6 0.0 0.5 0.0 4.5 0.0 18.5 8.8 72.7 6400 5.2 16.6 8.6 69.7 0.0 0.0 0.0 0.0 0.0 17.5 9.0 73.5 12800 l
Figure 3-17 is an SEM photomicrograph of tube R12C70-in the as-received condition showing the OD..
Table 3-16 is-the Auger in-depth profile of the OD.
The surface oxide was iron oxide, i
magnetite, with 7 to 16 a/o Ni.
Environmental contaminants were Si, S,
C, Ca, and 2n.
Cr was present after 8 pm was sputtered at a relative concentration somewhat less than that in the alloy.
In the as-received condition an IGSCC crack in'R12C70 had already been pulled to failure in the laboratory (Figure 3-18).
The tube l
had not been burst tested.
No other cracks could be found in the tubing received.
Figure 3-19 shows the exposed IGSCC crack, which is approximately 250 pm in depth Two grains were profiled, one near the crack opening, A,
and one near the crack tip, B.
3-21
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SEM Photomicrograph of 'As-received Section of Tubing R12C70 showing the OD Surface Table 3-16 AUGER IN-DEPTH COMPOSITION PROFILE OF A REGION 1
ON THE OD OF TUBE R12C70 i
j Atomic Percents Normalized Atomic i
Percents l
O Cr Fe Ni Si S
C Ca Zn Cr Fe Ni A
o i
l 15.3 0.0 7.3 1.5 2.7 1.4 70.6 0.2 1.1 0.0 83.4 16.6 0
l 17.9 0.0 13.7 2.4 4.6 1.7 57.6 0.2 1.8 0.0 85.2 14.8 100 17.2 0.0 17.3 3.0 4.5 1.4 54.7 0.6 1.2 0.0 85.1 14.9 200 1
l 17.1 0.0 20.3 2.8 4.1 1.3 51.7 0.7 1.9 0.0 87.8 12.2 400 j
16.5 0.0 25.6 2.5 4.1 1.1 48.1 1.0 1.0 0.0 91.0 9.0 800 18.0 0.0 29.0 2.8 4.1 1.1 42.9 0.9 1.3 0.0 91.3 8.7 1600 19.4 0.0 30.4 2.7 5.2 1.1 39.1 0.9 1.3 0.0 91.9 8.1 3200 i
j 22.2 0.0 31.9 2.6 6.1 1.0 33.4 1.6 1.4 0.0 92.5 7.5 6400 j
26.2 0.0 32.5 3.3 8.4 0.8 25.7 1.9 1.1 0.0 90.8 9.2 12800 32.4 0.0 33.8 4.0 11.2 0.6 14.9 2.3 1.0 0.0 89.5 10.5 27500 35.1 0.0 36.9 4.6 9.9 0.1 9.8 2.5 1.1 0.0 88.9 11.1 40000 36.9 0.0 40.8 6.7 8.6 0.0 5.0 2.1 0.0 0.0 85.9 14.1 60000 I
i 35.1 6.8 31.8 13.8 7.7 0.0 3.0 1.8 0.0 12.9 60.7 26.4 80000 33.1 8.0 29.3 21.5 5.3 0.0 1.5 1.3 0.0 13.6 49.8 36.6 97000 i
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SEM Photomicrograph of As-received Section of Tubing R12C70 Showing the Fracture Face Analyzed l
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SEM Photomicrograph Showing the Grains
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Profiled on the Fracture Face of R12C70 i
l 4
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3-23 1
i
EPRI Licensed Material Figure 3-20 is a higher magnification SEM photomicrograph of the fracture face showing that bands of deposits were present.
Tables 3-17 and 3-18 are the in-depth profiles of regions A and B respectivel'y.
No Cr was observed in the first 100A of the film.
After Cr was detected in the film, it had a relative concentration less than that in the alloy until approximately half the thickness l
of the film had been sputtered, 6400A on grain A and 1600A on' grain B.
The relative amounts of Fe were approximately 50% more than that in the alloy.
The contaminating species were Si, S,
and C.
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SEM Photomicrograph Showing Typical Region of the Fracture Face of R12C70 in High Magnification 1
3-24 1
i EPRILicensed M;tirlIl I
t Table 3-17 l
AUGER IN-DEPTH COMPOSITION PROFILE OF REGION A (CRACK HOUTH)
ON FRACTURE FACE OF' TUBE R12C70 ' SHOWN IN FIGURE 3-19 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Si S
C Cr Fe Ni' A
45.3 0.0 4.2 40.5 2.2 0.3 0.0 0.0 9.3 90.7 0
l 46.2 0.0 4.9 41.7 3.3 0.6 0.0 0.0 10.5 89.5 100 43.7 4.9 4.8 39.6 4.0 0.6 0.0 9.9 9.7 80.3 200 l
42.5 5.6 6.2 39.2 4.3 0.4 0.0 11.1 12.1 76.8 400 39.1 7.5 6.4 40.0 5.8 0.3 0.0 13.8 11.9 74.3 800 34.1 9.4 6.0 43.0 5.9 0.3 - 0.0 16.1 10.3 73.6 1600 25.2 12.3 7.4 47.6 5.7 0.0 0.0 18.3 11.0 70.6 3200 22.1 13.1 7.4 51.4 4.4 0.0 0.0 18.3 10.3 71.4 6400 16.0 16.1 9.0 55.8 2.3 0.0 0.0 19.9 11.2 68.9 12800 13.1 16.8 9.5 58.8 0.4 0.0 0.0 19.8 11.1 69.1 25000 l
14.0 15.8 9.4 55.4 0.2 0.0 0.0 19.7 11.6 68.7 50000 i
Table 3--18 AUGER IN-DEPTH COMPOSITION PROFILE OF REGION B i
(CRACK TIP)
ON FRACTURE FACE OF TUBE R12C70 SHOWN i
IN FIGURE 3-19 Atomic P.ercents Normalized Atomic t
Percents O
Cr Fe Ni Si S
C Cr Fe Ni A
45.5 0.0 4.3 37.1 0.2 0.6 12.2 0.010.589.5-0 44.9 0.0 4.4 43.6 0.4 1.1 5.7 0.0 9.3 90.7 100 42.5 5.0 5.2 43.0 0.2 0.6 3.5 -
9.4 9.8 80.8 200 39.3 8.8 4.9 44.3 0.0 0.5 2.1 15.2 8.4 78.3 400 i
32.3 10.3 5.4 48.5 0.2 0.3 - 3.0 16.1 8.5 75.5 800 21.7 12.6 7.7 55.5 0.0 0.2 2.4 16.7 10.1 '73.2 1600 17.3 14.1 8.8 57.6 0.0 0.0 2.2 17.5 11.0 71.5 3200 11.1 16.0 8.4 62.2 0.0 0.0 2.2 18.5 9.7 71.8 6400
{
12.7 16.1 9.1 60.1 0.0 0.0 2.0 18.9 10.7 70.5 12800 i
7.0 16.9 10.2 64.5 0.0 0.0 1.3 18.5 11.2 70.4 25000 13.8 15.2 9.0 57.0 0.0 0.0 5.0 18.7 11.1 70.1 50000 t
3-25
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1 Figure 3-21 shows an optical photomicrograph of the OD section of l
tubing from Tube R20C66.
The' cut across the axis of the tube f-extending across most of the section of tubing was made after this section was received from ABB/ Combustion Engineering.
The crack 1
{
which was analyzed is indicated by an arrow.
Shallow IGA was 1
j observed over most of the OD below the laboratory' cut
]
(Figure 3-22).
These cracks were apparently opened when the tube l
was burst tested.
Table 3-19 is the in-depth composition profile j
of the OD obtained from an area between IGA penetrations.
The 1
l impurities in the oxide were Si, S,
C and ca.
The major impurity
(
j is Si, which was in concentrations exceeding 15 a/o.
After j
sputtering 6 pm of oxide, the only impurity remaining was Ca,
[
which was less than 0.3 a/o.
Considering the alloy metals, Cr had l*
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Figure 3-21.
Optical Photomicrograph (6X) of As-received j
Section of Tubing from R20C66.
The Cut in the Section was j
Made After Receipt from ABB/ Combustion Engineering i
3-26 i
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SEM Photomicrograph of the OD of Tube R20C66 Showing the Shallow IGA i
Table 3-19 i
AUGER IN-DEPTH COMPOSITION PROFILE OF THE FILM l
ON THE OD OF TUBE R20C66 BETWEEN IGA j
Atomic Percents Normalized Atomic Percents l
O Cr Fe Ni Si S
C D
Cr Fe Ni A
l 37.7 8.5 11.4 10.2 4.9 0.1 27.1 0.0 28.3 37.8 33.9 0
l 41.1 7.8 12.3 15.7 16.8 0.1 5.4 0.4 21.7 34.5 43.8 650 1
48.9 4.4 14.2 9.9 16.9 0.2 4.0 0.3 15.5 50.0- 34.6 1600 I
l 48.5 2.9 13.8 13.2 16.4 0.2 3.5 0.3 9.8 46.1 44.1 6400 46.4 5.0 14.4 14.0 15.5 0.2 2.9 0.3 14.8 43.2 41.9 12800 38.4 10.4 13.5 23.4 10.5 0.1 2.4 0.4 22.0 28.6 49.4 25600 21.2 14.9 11.8 47.3 2.8 0.0 1.3 0.3 20.1 16.0 63.9 50000 l
17.7 15.8 10.2 53.2 1.1 0.0 1.4 0.3 19.9 12.9 67.2 60000 l
17.5 15.3 7.0 59.4 0.0 0.0 0.5 0.2 18.8 8.5 72.7 80000 1
16.6 15.3 7.2 60.6 0.0 0.0 0.0 0.4 18.4 8.6 73.0 90000 f
3-27
I EPRILicensed Mu;ri:I
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i a minimum in concentration after 6400A of film was removed with a corresponding increase in Fe.
These extremia.apparently occur at j
the scale / alloy interface since Ni,- Cr, and Fe. began their I
approach to the concentration in the, alloy as additional sputtering was performed.
Table 3-20.is the in-depth profile from~
the wall of an IGA penetration.
The' environmental species w-f incorporated'in.the oxide were'.Si,. S and C.
Aside from C, these species changed little in concentration to a depth;of-j
~
approximately 400A.
These envir'onmental species, slowly' decreased in concentration during additional sputtering.
Carbon. behaved
[
differently.
It.had a very high contamination level on the
)
surface and remained'in high concentrations throughout the film.
Relative to the alloy, Fe was enriched by approximately a' factor.
of two and Cr was slightly depleted.
i Table' 3-20 I
AUGER IN DEPTH. COMPOSITION PROFILE OF A REGION INSIDE A CRACK CAUSED BY IGA (TUBE -R20C66)
Atomic Percents Normalized Atomic l
Percents l
O Cr Fe Ni Si S
C Cr Fe
~ Ni A
t l-27.8 11.0 7.7 32.5 1.5 1.6 18.0 21.4 15.0 63.5 0-20.9 10.3 9.5 46.9 2.5 1.1 8.8 15.5
.14.2
' 7 0.3 -
100 20.0 10.7 10.1 48.7' 2.3 1.1 7.1 15.4 14.6 -70.0 150 19.6 10.3 10.7 49.0 2.5 1.0 6.9 14.7 15.3 70.0-200 19.0 11.1 11.0 50.3 1.8 1.0 5.8 15.3 15.2 69.5 250 18.8 10.3 11.3 49.8-2.3 1.0 6.5 14.5 15.8 69.7 300
[
18.2 10.9 11.7 51.3 1.5 0.8 5.4 14.8 15.9 69.4 350 18.4 10.2 11.8 50.4 1.9 0.9 6.4 14.1 16.3-69.5 400 18.8 10.5 12.6 51.5 0.0 0.5-6.2 14.0 16.8 69.1-450-15.9 11.5 11.9 53.3 0.0 0.7 ~
6.6 15.0 15.5 69.5 550 15.5 11.9 12.9 54.0 0.0 0.6 5.1 15.2 16.4 68.5-650 12.9 15.3 6.4 53.8 0.9 0.1 10.5 20.2 8.5 71.3 1600 Figure 3-23 shows.the grains profiled on~the. fracture' face'from tube R20C66, where grain A is near the crack mouth, grain D is-near the crack tip and Grains B and C are between A and D.
The in-depth'. composition profiles from the R20C66 fracture face are 1
3-28
EPRILicensed M:t:ri:1 given in Tables 3-21 (Grain A), 3-22 (Grain B), 3-23. (Grain C),
and 3-24 (Grain D).
Considering the relative concentrations of 1
the alloy metals, the average concentration of Cr in the films on the two grains analyzed nearest the crack mouth, Grains A and B, was approximately the same as that in the alloy; whereas, the average concentration of the Cr in the films on the two grains analyzed nearest the crack tip, Grains C and D, was slightly less than that in the alloy.
Fe was enriched in the film nearest the crack mouth, A,
and approximately the same as that in the alloy in the films on the other grains.
Environmental species found in the film were Si, S,
Ti, and C.
4 3-29
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SEM Photomicrograph Showing the Grains Analyzed on the Fracture Face of a Crack in Tube R20C66, l
Where A is Near the Crack Mouth, D is Near the Crack Tip and Grains B and C are Between the Crack Mouth and Crack Tip r
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Table 3-21 AUGER IN-DEPTH COMPOSITION PROFILE OF GRAIN A (CRACK HOUTH)
ON FRACTURE FACE OF TUBE R20C66 IN FIGURE 3-23 Atomic Percents Normalized ' Atomic Percents O
Cr Fe Ni Si S
Ti C
Cr Fe Ni A
24.4 3.2 2.2 16.4 4.1-1.3 0.6 - 47.7 14.7 10.2 75.1 0
29.4 3.0 2.5 12.8 4.0 2.2 0.5-45.5 16.5.13.8 69.6 200-29.2 4.4 4.2 15.9 5.3 2.0 0.7 38.3 17.9 17.2 64.9-400 29.4 4.9 5.3 16.9 6.9 1.7 0.5 34.5 18.0 19.5 62.5 800 28.3 7.2 5.1 22.7 4.4 1.5 0.5 30.4 20.6 14.5 64.9 1600 27.7 8.4 6.7 22.9 6.6 1.0 0.4 26.4 22.1 17.7 60.2 3200 I
29.1 9.3 9.6 31.2 5.5 0.7 0.4 14.3 18.6 19.1 62.3 6400-31.0 8.5 6.9 37.3 5.1 0.4 0.5 10.3 16.1 13.1 70.8 12800 30.2 9.5 7.0 39.5 5.0 0.5 0.6 7.7 17.0 12.4 70.5 12900-30.0 9.8 7.7 35.9 5.2 0.6 0.5 10.3 18.3 14.3 67.3 25600 27.3 12.1 5.7 42.4 2.4
- 0. 7.
0.5 8.9 20.1
'9.6 70.4 32000 26.0 12.1 6.8 47.5 2.6 0.2 0.0 5.0 18.2 10.2 71.6 56600 21.2 13.1 6.8 50.8 1.4 0.2
'O.5 6.0 18.5 9.7 71.8 66600 27.4 11.7 5.4 44.0 1.6 0.6 0.7 8.6 19.2 8.8 72.0 75600 f
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Table' 3-22 AUGER IN-DEPTH COMPOSITION ' PROFILE-OF GRAIN - B IN FIGURE ' 3-23' (TUBE R20C66)'
Atomic Percents -
Normalized Atomic Percents O
Cr Fe Ni Si S
Ti C'
- Cr Fe Ni A
27.0 5.3 0.0 15.9 1.7 5 0.6 48,0 25.1 0.0 74.9 0.-
30.1 7.5 2.0 24.5 2.4 16 0.0 31.9 22.1 5.8 72.1 200-31.9 8.3 2.6 28.6 2.7 1.3 0.0 24.5 21.0-6.6-72.4.
400 29.4 8.8 2.8 29.1 1.4 1.3 0.7-26.4 21.6 68 71.5.-
800' 34.5 8.1 3.8 35.2 4.9 1.2 0.4 12.0 17.2 8.2 74,7
-1600 27.6 10.1
'4.1 39.9 1.2 ' O.8 0,0' 16.3 18.7 7.573.7-3200 33.8 13.2 4.9 39.9 1.2 0.3 0.3
- 6.5 22.7 8.4 68.9 6400 35.5 12.8 4.4 40.4 1.1 0.3 0.0 5.4 22.2
-7.7 -70.1 12800' 35.8 12.1 4.6 41.2 0.9 0.5 0 '. 0 -
4.8 20.8 8.0 ~ 71.2 19200 34.1 12.8 4.8 41.0 1.4 ' O.1 0.5 5.3 21.9 8.2 69.9-25600-36.0 11.9
-3.8 42.5 1.0 0.3 0.5 4.1 20.4 6.5 73.1 32000 23.5 16.9
-5.2 47.0- 0.6 0.2 0.5 6.1 24.5!'7.6 68.0 56600 25.5 13.0 5.9 44.1 0.7 0.3 0.4 9.9 20.6 9.4 70.0 66600 27.4 11.6 5.1 43.7 2.1 0.2 0.6L 9.1 19.1 8.5 72.4 75600 3-32
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Table 3-23 AUGER IN-DEPTH COMPOSITION PROFILE OF GRAIN C l
IN FIGURE 3-23 (TUBE R20C66)
I l
Atomic Percents Normalized Atomic l
Percents O
Cr Fe Ni Si S
Ti C
'Cr' Fe Ni A-l
- 0.
39.7 6.1 3.6 31.9 5.4 1.5 0.3 11.4 14.8 8.7 76.5 41.1 6.7 3.6 29.6 4.3 1.0 0.0 13.8 16.7 9.0 74.3 200 39.9 7.1 3.4 31.4 4.6 1.0 0.3-12.1 17.0 8.2 74.9 400-l 1.7 0.5 3.2 21.0 8.3 70.8 800 t
42.0 10.9 4.3 37.0 0.4 32.2 10.3 3.0 44.3 0.0 1.4 0.4 8.4 17.9 5.2 76.9 1600 39.8 4.3 4.4 37.6 4.3 0.9
. 0.6 8.1 9.3
-9.6 81.1 3200
-1 37.1 8.7 5.3 37.4 4.5 1.0 0.3 5.6 16.9 10.4 72.7 6400 31.9 9.7 5.0 41.7 2.8 0.7 0.5-7.7 17.2 B.9 73.9 ~
12800 33.4 8.6 3.8 40.7 4.8 0.7 0.3 7.7 16.1 7.2 76.7 19200 33.2 8.4 - 4.6 40.6 3.9 0.6 0.5 8.1 15.7 8.6 75.7 25600 31.5 10.7 5.4 41-.6 2.8 0.5 0.4
-71 18.5-9.3 72.2 32000 28.6 11.8 4.9 43.6 1.9 0.5 0.5 8.2 19.6 8.1 72.3-56600 i
27.7 11.2 4.7 43.4 1.8 0.6 0.5
-10.1 18.9 7.9 73.2 66600 i
25.7 13.5 5.0 46.3 1.6 0.3
- 0.5 7.2 20.8 7.7 71.5 75600 i
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Table 3-24 i
AUGER IN-DEPTH COMPOSITION PROFILE OF GRAIN D (CRACK TIP)
ON FRACTURE FACE OF TUBE ; R2 0C6 6 IN FIGURE 3-23 Atomic Percents Normalized Atomic i
Percents j
O Cr Fe Ni Si S'
Ti
'O
'Cr Fe Ni
.A 42.4 4.7 0.0 36.0 0.3 1.6 0.0
- 15.0 11.5 0.0'88.5 0
41.7 6.7 4.1 39.2 0.0 1.6 0.0 6.7 13.4 8.2.78.4 200 i
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41.1 8.3 3.5 40.8 0.0 1.4 0.4 4.5 15.8 6.7 77.4 400 36.8 11.2 3.4-44.0 0.0 1.2 0.4 2.9 19.1 5.8 75.1-800
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28.1 8.6 3.2 32.8 1.9 1.2 0.5 23.8 19.3 7-. 2 7 3. 6 1600-18.5 11.9 4.9 60.3 0.0 0.3 0.3 3.8 15.4 6.4 78.3 3200 14.1 14.1 5.8 60.9 0.0 0.0..
0.6 4.5 17.4 7.2 75.3 6400 12.0 15.8 6.6 62.4 -- 0. 0 0.0 0.3 3.0 18.6 7.7 7 3.6 --
12800 12.1 15.0 7.0'60.5 0.0 0.3 0.6 4.5 18.2 8.5 73,3
-191200 13.8 14.2 6.0 59.0 0.0 0.0 05 6.'4 17.9 7.6 74.5_
25600 13.9 14.7 6.8 58.7 0.0 0.0' O.4 5.5 18.3 18.4 73.2 32000 8.2 16.7 5.5 65.0 0.0 0.0 0.6 4.0 19.2 6.4 74.5-56600 Figure 3-24 shows the section of Tube R12C8 as-received.
This section had only shallow intergranular cracks a few grains deep.
Table 3-25 is the in-depth composition profile from-the OD surface.
The surface film is a Fe-Ni oxide with a few percent of incorporated Cr. Silicon is the major environmental impurity.
Ca is present in concentrations up to 3.5 a/o. Zn and Cu are present in the 1-3 a/o range, and C1 is always less than 1-a/o.
The IGSCC.
fracture face analyzed was that exposed in the as-received condition shown in Figure 3-24 and in higher magnification in Figure 3-25.
Table 3-26 is the Auger in-depth composition profile of an area on the fracture surface.
Considering only the alloy metals, both Cr and Fe were present in relative quantities f
slightly less than those in the alloy.
The major impurity from the environment was Pb, which had a surface concentration of 14.5 a/o and decreased in concentration with depth.
Copper was present in the 5-6 a/o level in the outer 1600A and decreased with additional sputtering.
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SEM Photomicrograph of As-received Section from Tube R12C8 l
i Table 3-25 AUGER IN-DEPTH COMPOSITION PROFILE OF THE OD OF TUBE R12C8 l
Atomic Percents Normalized Atomic Percents O
Cr Fe Ni Si S
Cl C
Ca Cb Zn-Cr Fe Ni A
i l
42.1 0.0 9.2 5.0 7.2 1.4 0.5 29.5 1.2 1.3 2.6 0.064.635.4 0
l 47.2 0.0 10.4 4.6 13.4 1.3 0.4 17.1 1.7 1.1 2.8 0.069.530.5 50 l
47.6 1.4 10.0 4.5 16.3 1.3 0.3 12.7 1.7 1.1 3.0 8.662.928.5 100 48.4 0.0 10.2 4.4 19.0 1.2 0.3 10.7 1.9 1.2 2.6 0.069.730.3 200 47.2 2.3 9.4 4.0 20.4 1.1 0.3 9.3 2.1 1.3 2.6 14.5 60.0 25.6 400 i
45.9 1.8 11.2 4.5 20.6 1.1 0.2 8.8 2.3 1.1 2.6 10.5 64.0 25.5 800 l
44.4 1.6 13.4 5.4 19.8 1.1 0.1 8.9 2.6 1.1 1.5 7.665.726.7 1600 l
l 44.5 1.5 16.0 5.0 18.5 0.8 0.1 7.5 2.8 1.3 2.1 6.971.022.1 3200 42.0 1.8 19.6 6.2 17.5 0.8 0.2 5.5 3.2 1.0 2.1 6.671.022.4 6400 38.9 2.0 25.0 6.6 15.5 0.5 0.2 4.5 3.5 0.9 2.3 5.9 74.3 19.8 12800 35.8 2.7 30.9 8.5 12.9 0.2 0.1 3.0 3.3 0.7 1.8 6.4 73.4 20.2 20000 33.4 3.5 33.7 14.2 8.9 0.2 0.0 2.0 2.8 0.0 1.3 6.865.627.6 12800 9.6 18.5 9.7 60.5 0.0 0.0 0.0 1.7 0.0 0.0 0.0 20.8 10.9 68.2 90000 i
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SEM Photomicrograph of the Fracture Face Analyzed From Tube R12C8 Table 3-26 AUGER IN-DEPTH COMPOSITION PROFILE OF THE FRACTURE FACE OF TUBE R12C8 Atomic Percents Normalized Atomic Percents O
Cr Fe Ni C
0; Pb Cr Fe Ni A
l 39.7 7.3 0.0 26.2 6.6 5.9 14.3 21.9 0.0 78.1 0
l 41.8 6.8 1.7 29.2 2.7 6.0 11.8 17.9 4.6 77.4 50 41.1 6.7 1.8 31.5 2.0 5.9 11.1 16.8 4.4 78.7 100 i
38.7 6.7 1.9 33.8 2.5 5.9 10.4 15.9 4.5 79.6 200 37.0 6,7 2.4 36.3 1.6 5.6 9.8 14.5 5.3 80.2 400 l
36.6 7.1 3.6 37.3 1.7 5.1 8.7 14.7 7.4 77.8 800 l
35.0 10.3 5.0 35.4 2.1 5.3 6.9 20.4 9.8 69.8 1600 l
27.1 11.1 5.5 46.5 2.1 3.5 4.2 17.6 8.8 73.6 3200 22.3 13.7 6.4 49.8 3.7 2.4 1.7 19.5 9.2 71.3 6400 l
19.0 16.1 7.2 51.5 4.4 1.3 0.6 21.5 9.6 68.9 12800 17.6 17.2 7.6 52.0 4.9 0.8 0.0 22.4 9.9 67.7 25000 d
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20.4 16.3 6.1 48.5 7.9 0.7 0.0 23.0 8.6 68.3 50000
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On all surfaces analyzed, Fe had the distinctive magnetite spectrum.
Chromium and Ni were in mixed oxide / hydroxide states.
An approximate deconvolution of the Ni 2P lines gave the following:
tube R25C58 - 40% Ni(OH)2 / 60% NiO, tube R29C70 - 35% Ni(OH)2 /
65% NiO on the OD and 404 Ni(OH)2 / 65% NiO on the fracture face, tube R30C64 - 90% Ni(OH)2 / 10% Nio on the OD and 75%
Ni(OH)2 / 25% NiO on the fracture face, tube R16C74 - 100%
l Ni(OH)2 on the OD and 70-% Ni(OH)2 / 30% NiO on the fracture face, tube R12C70 - 4 0% Ni(OH) 2 / 30% NiO on the OD and fracture L
face, tube R20C66 - 100% Ni(OH)2 on the OD and 75% Ni(OH)2 / 25i l
NiO on the fracture face, tube R12C8 - 70% Ni(OH)2 / 25% NiO on the OD (the fracture face was not analyzed because'it was too small to give unambiguous results).
The spectra distinctive of 0,
CrOOH and Cr(OH)3 have large linewidths relative to their Cr2 3
energies of separation which makes them difficult to deconvolute.
However, Cr203 has a distinctive double peak which was not observed on any of the areas analyzed.
This suggests that Cr was at least 80% to 90% Cr(OH) 3 and/or CrOOH.
When observed, Cu was present either as metallic Cu or Cu O; these XPS lines are not distinguishable.
Silicon was present as silicate.
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DISCUSSION ia The underlying hypothesis used in relating the Auger and XPS I
analysis of the corrosion products on the fracture faces and OD' tube / tube support plate. intersections to crevice chemistries is i
that the oxides found in these locations are predictable from the Pourbaix diagrams of the pure metals..These diagrams _-[51 are.
shown~in Figures 4-1,-
4-2 and 4-3'for Fe, Cr, and Ni at 288 C with activities of dissolved species of 10-3 Nickel has the1 broadest i
range of stability at high pH's with nickel oxide-stable' starting f
at potentials just above the hydrogen.line, "a"i -(potentials below l
1 l
which water decomposes 'to form hydrogen gas)' to' approximatelyL pH l
15.
Ni metal is stable at all alkaline and caustic pH's.a't f
potentials on the hydrogen-line.
Chromium is'leastt stable having only soluble species. stable at pH's'above 9.5 under: oxidizing conditions and to potentials several hundred mV below;the hydrogen line.
The extent of the-stability of iron at high'pH's is-between I
that'of Cr and Ni.
Iron has a band of potentials both above~and.
below the hydrogen line at pH's higher than-11 where soluble.HFeOp-
.is the stable. species.
I The surface composition-of Alloy 600-laboratory specimens exposed-t to caustic solutions can be predicted'by superimposing the l
Pourbaix diagrams for pure metals.
Figure 4-4 shows the-Auger l
in-depth composition profile for Alloy 600 exposed to a ' 315 C,10% -
l l
NaOH solution at open circuit, which indicates a'dealloyed' surface i
enriched in Ni and depleted in Fe and Cr- (1) The-potential-of the I
system is on the hydrogen-line.
A comparison of the'Pourbaix.
diagrams for Fe, Cr, and Ni predict that the most ~ stable insoluble-p-
phase is metallic Ni, which is. exactly wha't is observed.
The'200A'
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oxide film,:which-is on the surface, formed when the autoclave-l 4-1 a
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Potential-pH Diagram for the Fe-water System (at 2 8 8'C) with Dissolved Species Activities of 10-3 Q) cooled down.
Figure 4-5 shows the Auger in-depth profile of an Alloy 600 specimen which was exposed to 50% NaOH at 320 C while polarized 150 mV above the open circuit potential. (1) The surface has a film composed almost entirely of nickel oxide, again in accordance with the Pourbaix diagrams.
Figure 4-6 shows Japanese results (2) for Auger analysis of Alloy 600 which had been exposed to solutions of sulfuric acid, sodium sulfate and sodium hydroxide having varying pH's.
As the pH decreased, Cr enriched uniformly, Ni decreased uniformly and Fe increased slightly.
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Potential-pH Diagram for the Cr-water System (at 288 C) with Dissolved Species Activities of 10-3 [g)
Although the practice of relating the Cr concentration in the oxide film on alloy 600 to the pH in the tube / tube support plate crevice has a valid thermodynamic and laboratory basis, it has limitations which must be considered.
The major uncertainty arises because the thermodynamic and laboratory data were obtained for environments much simpler than those existing when the films were formed on the steam generator tubes.
The crevice environments are concentrated solutions of environmental species including high concentrations of iron ions resulting from corrosion of the support plate and other steel components exposed to the secondary water.
Laboratory data for the corrosion products formed in these complex environments does not yet exist.
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Potential-pH Diagram for the Ni-water System (at 288 C) with Dissolved Species Activities of 10-3 g)
A common feature in the in-depth composition profiles of the OD of all the tubes plugged and removcd in 1991 (Tables 3-3, 3-8, 3-12, and 3-16) is the low chromium concentration near the surf;ce of the film.
The films on the OD of R30C64 (Table 3-8),
R16C74 (Table 3-12), and R12C70 (Table 3-16) were completely depleted of Cr during the first few thousand Angstroms of sputtering.
Although Cr was not completely absent in the in-depth composition profile of the OD of R29C70, several points on the surface were found where there was no Cr, some of which were pure nickel oxide (Table 3-2).
The film on R29C70 was not homogeneous in the lateral direction because of spalling which occurred during handling or burst testing.
The Fe content in these films, when 4-4
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O.125 0.250 0.375 0.500.
1.0 2.0 3.0 4.0 5.0 6.0 SPUTTER DEPTH ( m)
Figure 4-4.
Auger In-Depth Composition Profile for Alloy 600 Which Was Exposed to 50% NaOH at 320 C so 7..
=
y awo ALLOY 600, CD h
50% NaOH,150mV
- ~
lE O
o a-y cr F.
10 -
Ni 4
5 0
0 10000 20000 30000 40000 50000 60000 SPUTTERING DEPTH (A)
Figure 4-5.
Auger In-Depth Composition Profile for Alloy 600 Which Had Been Exposed to 50% NaOH at 320*C While Polarized 150 mv Above the Corrosion Potential, Ecorr 4-5
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10 12 14 pH Figure 4-6.
Change in Fe,
Cr, and Ni Composition of the H SO /Na2SO /
Surface Film on Alloy 600 After Exposure to 2
4 4
NaOH Solutions of Varying pH's (280 C)
[1]
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compared with Cr and Ni, was several times higher than that in the alloy.
This reflects the high concentration of Fe in the crevice solution as discussed above.
However, the high Ni content in the film on the OD suggests that this film is not simply a deposition product.
Even so, a high pH environment would be unfavorable for deposition of Cr containing oxides.
The profiles of areas on the fracture faces, all of which were intergranular, from cracks in these three tubes also have less Cr, relative to Fe and Ni, than in the alloy.
The high Fe levels found on the OD were not present on the these fracture faces.
The Fe, relative to Cr and Ni, on most areas profiled on these fracture faces was less than or approximately the same as that in the alloy.
Tube R12C8 was also removed in 1991.
However, unlike the three tubes discussed above, it was plugged in 1989.
Thus, it was exposed to the secondary water chemistry and not to the concentrated crevice solution for two years prior to its removal.
It is not clear what changes, if any, this exposure to the secondary water chemistry would introduce to a film formed in the 4-6 L-__-- _
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The in-depth composition profile of the film on the OD (Table 3-25) was similar to those plugged and removed in 1991 as discussed previously.
The film profiled on the fracture face (Table 3-26) had Fe and Cr levels slightly less than those in the alloy.
Thus, the chemistries of the films on the OD and fracture faces of tubes R12CB, R12C70, R16C74 and R29C70 suggest the existence of strongly alkaline or caustic tube / tube support plate crevices.
However, the results from R20C66, while not suggesting an acid crevice, do suggest a crevice chemistry with a pH lower than those which existed during the formation of the films on R12CS, R12C70, D
R16C74 and R29C70.
This is based on the profiles of the films on the OD (Table 3-19), in an IGA penetration (Table 3-20) and on a fracture face (Tables 3-21 through 3-24), which are not depleted in Cr, but have a concentration approximately the same as the alloy, relative to Fe and Ni, when averaged over all depths p.
analyzed.
Tube R20C66 was plugged in 1990 and removed in 1991.
Thus, it was not exposed to the concentrated crevice environment for a period prior to its removal.
It is not clear why the Cr levels are different for R20C66.
It could be explained by the presence of deposits.
There is considerably more scatter in the data in the profiles than that from the other tubes.
The film on the OD of R25C58 (Table 3-1), which was removed in 1986, had relative Cr concentrations as high as those observed on R20C66.
The film on R25C58 differed from those on the OD of the other tubes since the relative Ni concentration was lower, silica was not incorporated in the film (the OD films on other tubes had maximum concentrations of 10 to 20 a/o silica), and the Zn content was several times higher than that in the films on other sections of tubing.
The presence of Zn suggests that the crevice chemistry was neither highly acidic nor strongly alkaline since zinc oxide is soluble in these conditions.
Zine has been observed in films on alloy 600 which had been exposed to mildly acidic solutions at 2 8 8'C (6).
Since the Trojan condenser was replaced with a Ti 4-7
EPRI Licensed Material condenser during the 1987 refueling outage, nothing can be concluded from the absence of Zn in the films on tubes removed after their date.
The presence of silica in the crevice could be an indication of a highly alkaline or caustic condition, under which conditions silica is soluble, or a result of reduced demineralizer efficiency resulting from continuous on line borate treatment, which was initiated in 1989.
l l
4-8
EPRILicensed Malertal Section 5 CONCLUSIONS The tubes removed in 1991 had Cr depletion in the films of corrosion products on the OD and fracture face of sections of tubing from tube / tube support plate intersections.
The tube removed in 1986 had a Cr enriched corrosion product film on the OD of a tube / tube support plate intersection.
Available laboratory data and thermodynamic considerations suggest that Cr depletion correlates with a caustic to highly alkaline environment and Cr enrichment correlates with a neutral to acidic environment.
5-1
EPRILicensed Material e *-
- b **
Q EPRILicensed Material Section 6 REFERENCES n
0 I-1.
J.B. Lumsden, " Mechanisms for Formation and Disruption of Surface Oxides," EPRI Final Report NP-5368, Electric Power Research Institute, Palo Alto, CA; August 1987 2.
H.
Takamatsu, K.
- Matsueda, K.
- Onimura, K. Arioka, S.
Tokunga and K. Katsura, " IGA /IGSCC Propagation Behaviors of Alloy 600," Proceedings of the Fourth International Svmoosium on Environmental Decradation of Materials in Nuclear power Systems-Water Reactors. 1989, Jekyll Island, USA; 1990; pp. 7 7-44.
3.
J.B.
Lumsden, " Oxide Film Compositions and Morphology or Alloy 600 Tubes from Steam Generators-North Anna Unit 1 and Point Beach Unit 1," EPRI Final Report NP-5712, Electric Power Research Institute, Palo Alto, CA; April 1988.
~
4.
J.B. Lumsden, "The Relationship Between Surface Oxide Chemiscries and the Chemistries in Steam Generator Crevices," Proceedings of the Fourth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. 1989, Jekyll Island, USA; 1990; pp. 6 6-51.
'N 5.
P.L. Daniel and S.L. Harper, "Use of Pourbaix Diagrams to Infer Local Pitting Conditions," EPRI Tonical Report NP-4831, Electric Power Research Institute, Palo Alto, CA; October 1986.
6-1
EPRI Licensed Material 6.
A.M. McKay, " Mechanisms of Venting in Nuclear Steam Generator," Corrosion /82, Preprint No. 214, NACE, Houston, TX (1982).
6-2
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