ML20203A231
| ML20203A231 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/23/1985 |
| From: | Inman S, Koch D, Monter J BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19292F311 | List:
|
| References | |
| NUDOCS 8604160258 | |
| Download: ML20203A231 (63) | |
Text
~ .y?;6C0koWilcOx a .roemon company muence, oNo +460 nc.: inw. n TJ l J. F. CUVELIER - CUSTOMER SERVICE, SPIS From J. V. MONTER - MATERIALS PERFORMANCE SECTION, ARC S. C. INMAN - NUCLEAR MATERIALS SECTION, LRC D W_ KorH - MATFRTAl9 A CHFMirAl CMCTMFFDTMC RFRVTrF9 Mpn Cust. File No.
ARKANSAS POWER AND LIGHT ARC R00:85:S233-01:01 iRc Rnn As q??1-01 n1 suk), Date CORROSION TEST OF A MECHANICALLY SLEEVED ANO-1 OTSG TUBE OCTOBER 23, 1985 l'"~~~~~~~~""~~~***"
NOW-PRoPRIETnffY Wrts1oW
SUMMARY
A corrosion test was performed on a section of ANO-10TSG tubing with a roller expanded sleeve installed. The test specimen was prepared using a piece of tubing known to contain shallow intergranular attack on the outside surface.
The sleeved specimen was exposed in an autoclave to slightly faulted 0TSG secondary side environment at both operating conditions and wet layup conditions.
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The purpose of the corrosion test was to evaluate the effect of the expanded j sleeve design on existing interg'. anular attack (IGA) on the ANO-1 steam generator .i tubes. The corrosion test showed IGA within the same range of depth as observed '
in specimens before and af ter the corrosion tests. Therefore, it is concluded that the roller expansion did not cause further tube degradation under these corrosion tests.
KEY WORDS ANO-1 Nuclear Steam Generator Corrosion Sleeving Intergranular Attack 1
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Babcock G Wilc;x ac 2 :aw. we a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 3 TABLE OF CONTENTS
SUMMARY
1.0 INTRODUCTION
1.1 Objective 2.0 METHODS AND RESULTS 2.1 Specimen Preparation 2.2 Diameter Measurements and Strain Calculations 2.3 Corrosion Testing 2.3.1 Test System 2.3.2 Test Program 2.3.2.1 Operating Conditicns - High Temperature 2.3.2.2 Operating Conditions - Low Temperature (Layup) 2.4 Post-Test Sample Examinations 2.4.1 Visual Inspection and Photography 2.4.2 Radiography and Penetrant Testing 2.4.3 Sectioning 2.4.4 Scanning Electron Microscopy 2.4.4.1 Control Specimens (not corrosion tested) 2.4.4.2 2000-Hour Test Sample 2.4.4.3 2000-Hour + Wet Layup Test Sample 2.4.5 Metallography 2.4.5.1 Control Specimens
- 2.4.5.2 2000-Hour Test Sample 2.4.5.3 2000-Hour + Wet Layup Test Sample 2.4.5.4 Unrolled Region Specimen 3.0 DISCUSSION 4.0 CONCLUSI0HS l
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a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 4 LIST OF FIGURES Number 2-1 Photograph of corrosion test sample B1112-19-5CS 2-2 Schecatic of corrosion test sample B112-19-SCS 2-3 Corrosion test system 2-4 Schematic of corrosion test system 2-5 Schematic of the mounted sample assembly 2-6 Test sample assembly 2-7 Schematic drawing of the sample and autoclave and stressing fixtures 2-8 Sleeved sample mounted on the autoclave head 2-9 Loading fixture for the ANO-1 sleeved corrosion sample 2-10 Assembled test sample with chemical injection tubes 2-11 Autoclave system in toreground and control panel in lef t background 2-12 Wet layup sample prior to testing 2-13 Inlet temperature 2-14 Outlet temperature 2-15 Test sample temperature near contaminated water injection point 2-16 Externally applied tensile load 2-17 Autoclave pressure 2-18 Test sample internal pressure 2-19 Photographs of test samples after corrosion testing 2-20 Photographs of deposit on 2000-hour test sample 2-21 Photographs of deposit on 2000-hour + wet layup test sample 2-22 Radiograph prints of 2000-hour test sample 2-23 Radiograph prints of 2000-hour + wet layup test sample 2-24 Section diagrams for corrosion test samples 2-25 SEM photomicrographs of control specimen CS-A outer surface 2-26 SEM photomicrographs of expanded region of 2000-hour test sample
, 2-27 SEM photomicrographs of lower transition region of 2000-hour test sample
! 2-28 SEM photomicrographs of expanded region of 2000-hour + wet layup test sample 2-29 SEM photomicrographs of upper transition region of 2000-hour + wet layup test sample 2-30 Photomicrographs of control specimens CS-A and CS-B 2-31 Photomicrographs of expanded region of 2000-hour test sample -
first grind 2-32 Photomicrographs of expanded region of 2000-hour test sample -
second grind 3 2-33 Photomicrographs of expanded region of 2000-hour test sample - l third grind 2-34 Photomicrographs of expanded region of 2000-hour + wet layup test sample - first grind 2-35 Photomicrographs of expanded region of 2000-hour + wet layup test sample - second grind 2-36 ' Photomicrographs of lower transition region of 2000-hour + wet layup test sample 2-37 Photomicrographs of specimen RC
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RDD:85:5233-01:01/RDD:85:5223-06:01 Page 5 LIST OF TABLES Number 2-1 Diameter Data Analysis Results for Test Sample and Sleeve 2-2 i Contaminated Feedwater Chemistry l 2-3 Layup Water Tank Chemistry !
2-4 Autoclave Layup Water Chemistry '
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1.0 INTRODUCTION
Intergranular attack (IGA) was detected on the outer surface of Alloy 600 tubes which were removed from the "B" steam gencrator at the Arkansas Nuclear One Unit 1 (ANO-1) power plant in January,1983 (1). The attack occurred in the upper region of both once-through steam ganerators (OTSG). IGA in the tubing below the upper tubesheet (UTS) down to the 14th support plate was measured to a maximum depth of 7 mils. IGA within the UTS has resulted in through-wall failures. The IGA within the UTS is generally located within six (6) inches of the secondary face.
Babcock & Wilcox (B&W) proposed to the plant owner, Arkansas Power and ,
Light, that a mechanically rolled sleeve be used to extend the life of severely affected tubes. The rolled sleeve technique utilizes a roller expander to mechanically expand the sleeve against the inner surface of the tube in a free-span region to provide a seal. Since the tubes are stressed in the hoop and axial directions due to the expansion, questions were raised as to whether the stresses would cause opening and/or radial propagation of existing IGA. If this occurs, the tubing may then be susceptible to cracking or further corrosion damage. This corrosion test program addresses these concerns as expressed by AP&L.
l 1.1 OBJECTIVE
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The objective of this program was to evaluate the effect of the expanded sleeve design on existing IGA on ANO-1 steam generator tubes. To assess the performance of the sleeve design in the ANO-1 environment and the effect of sleeving on the existing ANO-1 tubing, B&W tested a segment of sleeved ANO-1 tubing under simulatad water chemistry conditions with contaminants two to six times greater than the normal ANO-1 operating and wet layup chemistry.
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Babc:::ck G Wil=x "62 * *8 l a McDemott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 7 2.0 METHODS AND RESULTS 2.1 SPECIMEN PREPARATION The corrosion test sample was selected from tube B112-19 in the region from 78 to 86 inches from the top of the upper tubesheet and labeled B112-19-5CS.
This region was adjacent to regions in which IGA up to 18% throughwall was previously observed (1_). Half-inch control specimens were sectioned from the top and bottom of the sample and labeled CS-A and CS-B, respectively. Therefore, the final length of the test sample tube was 7 inches.
The test sample was radiologically decontaminated on the inner surface using ,
the procedure outlined in a previous report (2_). Gamma spectroscopy was used to !
count the sample for radionuclides following a rinse with deionized water.
l Results snowed the sample to contain less than 1 microcurie of Co-60 '
ra'dioa ctivi ty. This amount of activity is acceptable for receiving and handling l
at the ARC. '
Personnel from the B&W Special Products and Integrated Field Services (SPIS) roller expanded an 8-inch long thermally treated (1325'F for 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />) Alloy 600 sleeve inside the test sample according to the procedure in Appendix A. An 0.015-inch hole was drilled through the tube wall 1/4 inch below the top to 1 l
permit the contaminant solution to reach the. crevice between the tube and the
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sleeve. A cartridge heater was placed inside the sleeve to provide heat transfer '
during the test. Alloy 600 plugs and connectors required for accommodation in the autoclave were then TIG welded onto the test sample using Inconel 82 filler me tal . A photograph of completed test sample B112-19-5CS is shown in Figure 2-1 and a schematic showing the locations of the rolls is shown in Figure 2-2. The outer surface of the tube appeared typical of OTSG tubes periodically removed from service, with some " dry-out" stains present along the length. I l
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. RDO:85:5233-01:01/RDD:85:5223-06:01 i 2.2 DIAMETER MEASUREMENTS AND STRAIN CALCULATIONS Innec and outer diameter (ID and 00) measurements were made on the test sample and sleeve' in the expanded regions prior to and following sleeve installa tion. These data are listed in Table 2-1.
The tube expansion is at the upper limit of the range of values which were qualified during the sleeve
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qualification program (3) and corresponds to a tube strain 2.3 CORROSION TESTING The sleeved test sample was subjected to a corrosion test at the Alliance Research Center (ARC), for 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, using an environment to simulate faulted OTSG secondary side chemistry conditions. To simulate primary side conditions, the sleeved tube assembly was heated with an electrical cartridge heater. The secondary side test environment was steam with droplets of simulated faulted ANO-1 feedwater ' impinging on the tube so that the droplets boiled and concentrated contaminants in the tube / sleeve crevice and on the outer surface of the rolled area of the tube. .
Under these conditions an important concern regarding tube integrity is addressed. If sulfur compounds, already present on the tube surface and within the existing IGA penetrations, were going to cause stress corrosion cracking of the tube, they would be expected to do so within the 2000-hour test period.
Af ter the 2000-hour autoclave simulation of ANO-1 operating conditions, the sleeved tube assembly was cut circumferentially sent to the Lynchburg Research Center (LRC) for metallographic examination. The other was subjected to simulated wet layup conditions at 150*F and subsequently examined for evidence of cracking. The layup test was to determine if sulfur compounds on the surface of the tube would cause cracking at low temperatures where reduced sulfur species were mest likely to cause damage.
The following sections describe the corrosion testing performed on the sleeved ANO-1 tube specinen. Included is a description of the test system, the 2000-hour exposure of the specimen in an autoclave, and the subsequent wet layup. test.
Babcock G Wilecx ac 2:n.v. m s a McDermor: company RDD:85:5233-01:01/RDD:85:5223-06:01' Page 12 2.3.1 Test System -
The corrosion test was performed in the refreshed autoclave system shown pictorially in Figure 2-3 and schematically in Figure 2-4. Flow through the system included:
e steam flow generated from high purity feedwater, and a " faulted feedwater" (as described below) sputtered onto and flashed to steam on the specimen surface.
Steam exited the system through a condenser and a pressure ket-down system. The autoclave used was a one-liter Alloy 600 autoclave.
An Alloy 600 autoclave head was madified to accept the test sample. Figure 2-5 is a schematic of the stressed and internally heated sample assembly. The test sample consisted of the sleeved ANO-1 tube previously described with an internal cartridge heater (3/8-inch OD x 6 inches long; 120 volts; 500 watts).
Figure 2-6 shows the test assembly with a threaded Alloy 600 plug welded in one end of the tube. A length of 1/2-inch OD Alloy 600 tubing was welded to the other end of the tube specimen via an Alloy 600 reducing coupling and extended through the autoclave cover and a Conax pressure fitting. As shown schematically in Figure 2-7 and pictorially in Figure 2-8, the 1/2-inch OD tube terminates with a Swage-lok connector.into a special stainless steel fitting. The special fitting allows for (see Figure 2-9):
e sealing of the cartridge heater lead wires, e connection to the load cell for application of a constant tensile load to the sample using a compressed spring, and e internally pressurizing the sample with an inert gas.
A bottom plate of Alloy 600 was positioned on support columns using Alloy 600 nuts and spacers. The sample was secured to the bottom plate using an Alloy 600 nut. This setup is inverted from the actual upper tubesheet damage area situation. The reason for this inversion was that the velocity in the operating l OTSG units, which carries the contaminants upward and deposits them on the l i
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STEAM GENERATOR Figure 2-7. Schematic drawing of the sample and autoclave and stressing fixtures.
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Feedwater for the test system was stored in a 500 gallon feedtank. It was pumped into the preheater at a rate of 0.5 gpm using a liodel 7120 Pulsafeeder variable-displacement, diaphragm pump. The high-pressure feedwater was heated '
and vaporized in a preheater/ steam generator. The preheater/ steam generator was made of 0.125 inch OD x 35 mil wall Type 316 stainless steel tubing wound around a steel cylinder, wrapped with tape heaters, and subsequently covered with insulation.
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Babcock O Wifrx ac-2 :n m a McDemott company 4 RDD:85:5233-01:01/RDD:85:5223-06:01 Page 19 Superheated steam from the preheater/ steam generator passed through the autoclave, af ter which it was condensed and cooled to room temperature by a -
water-jacketed cooling coil. The condensate then exited the high pressure system through a back pressure regulator. The effluent at atmospheric pressure passed through a flowmeter to a sampling line and a drain line.
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, The " faulted feedwater" system is shown as a part of the Figure 2-4. The term " faulted feedwater" is used here to distinguish the water with ccntrolled ppb level addition of chemicals from the very high-purity water used to make steam for the test system. The contaminated water was mixed and stored in a 60 ga'llon Type 316 stainless steel feedtank. Two Microflo Pulsafeeder pumps pumped the solution through 1/16-inch lines to two injection points (see Figure 2-10).
Injection tube No. I was placed 1/4 inch from the top of the sample near a small hole that was drilled through the tube. The position of this injection tube allowed the contaminated water to be directed into the tube / sleeve crevice.
Injection tube No. 2 was directed onto the shoulder of the uppermost roll transition. The locations of the injection tubes are shown schematically in Figure 2-5. Prior to the test, each contaminant pump was calibrated to deliver 2 ml per minute.
The test system monitoring and control panel is shown in the lef t background in Figure 2-11. Additional gauges and controls are shown in Figure 2-3.
Parameters monitored included:
e Six temperatures
- TC #1 contacting the expanded (rolled) portion of the test sample TC #2 contacting .
- TC #3 in the bottom of the autoclave near the steam inlet
- TC #4 in the center of the autoclave near the sample
- TC #5 in the top of the autoclave near the steam outlet I
- TC #6 in the inlet steam line 1 i
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Crbecck G Wilcox a Mccerma: co npany RDD:85:5233-01:01/RDD:85:5223-06:01 Page 20 e Two pressures
- autoclave internal pressure
- specimen internal pressure e Flow rates
- total autoclave effluent
- two chemical injection flow rates e Faulted feedwater tank level e Tensile load on test sample e Time at temperature with contaminated water injection.
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The primary thermocouple locations are shown in Figure 2-5. Thermocouple 4 was the control thermocouple for the autoclave heaters. Temperature readings for thermocouples 1 and 2 were used as a guide to determine the voltage setting for the cartridge heater. The preheater/ steam generator temperature was controlled by thermocouple 6 which was positioned in the steam inlet line at the bottom of the autoclave. Additional thermocouples were used for high-temperature safety limit switches for the autoclave and the preheater/ steam generator.
i Embcock G Wilrx ac-2 inw. aw a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 22 Autoclave and test sample internal pressures were manually controlled, but the system included pressure switches for high-pressure safety alarms. The steam ~
and contaminated water feed rates and the sample tensile load were also manually controlled.
2.3.2 Test Program The sleeved ANO-1 tube sample with the cartridge heater in place was installed in the autoclave head. Thermocouples were attached to the sample and head assembly. Contaminated water injection tubes were positioned as described previously. The head assembly was put in place on the autoclave and the exterior thermocouples and tubing connections were made.
Power was then applied to the autoclave and the preheater/ steam generator and steam flow through the autoclave was established. An external tensile load of about 500 lbs. and an internal, pressure of about 2150 psig was then applied to the sample and contaminated water injection was started. This high-temperature test ran for 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />s: 1950 hours0.0226 days <br />0.542 hours <br />0.00322 weeks <br />7.41975e-4 months <br /> with contaminated water injection and the final 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> without contaminated water injection.
After completing the high-temperature test, the sample was removed from the l
autoclave and the lower roll expansion was removed and sent to the LRC for '
examination. The remainder of the sample was put back into the autoclave for the wet layup phase of the program. Figure 2-12 shows the sample prior to the wet layup test. After 3 weeks exposure (500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />) to layup water, the sample was removed and sent to the LRC for examination.
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2.3.2.1 Operatina Conditions - High Temperature The following high-purity feedwater chemistry was used for the preheater/
stea n generator. The pH at 75*F was 9.3 to 9.6, obtained by the addition of ammonium hydroxide. Residual hydrazine (used as an oxygen scavenger) ranged from 110 to 275 ppb. The specific conductivity of the feedwater was 8.6 to 13.3 umhos/cm. The feed rate was 0.5 gpm.
The contaninatad water used to simulate ANO-1 water chemistry was a synthetic solution based on AH0-1 feedwater chemistry for the period of August, i
r Babcock G Wil:Cx "o2 :am 3*
a McDermon company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 24 -
1981 through August, 1983. Target contaminant species concentrations were two to six times greater than those below which the normal AN0-1 feedwater contaminants remained 90% of the time. These target concentrations and the actual concentrations achieved are shown in Table 2-2.
The detailed technical basis, including calculations, for the target contaminant concentrations to be injected on the specimen may be found in Appendix B. The contaminant concentrations were selected by using typical contaminant concentrations in ANO-1 OTSG feedwater to give an equivalent quantity per unit area on the test specimen. The calculations assume that the contaminants will be deposited uniformly over the entire surface area of both the steam generator tubing and the specimen. The actual distribution for the deposition of the dissolved contaminant in the OTSG is not known. However, it seems reasonable to conclude that the contaminant concentrations, which were injected directly upon the specimen in this corrosion test, were significantly greater than those which would be experienced in the OTSG at the location of the mechanical expansion joints, i.e. near the fifteenth support plate.
Figures 2-13 to 2-15 show the range of temperatures occurring through the period of autoclave operation. Temperatures shown are for the steam inlet ,
! (Figure 2-13), the steam outlet (Figure 2-14), and the test sample (Figure 2-15). Through the first 16 days of the test, an intensive effort was made to attain original target test conditions:
The system was not stable under these conditions and temperatures varied erratically as condensation and boiling occurred in different parts of the system.
l 1
1
Babe:Mk G Wil2OX **'""*' l a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 .Page 25 i
Table 2-2 CONTAMINATED FEEDWATER CHEMISTRY Concentration (2)
Contaminant III 1st Tank 2nd Tank 3rd Tank 4th Tank Target Sulfate, ppb 29 36 NA(3) 38 30 Silica, ppb 5 11 13 10 30 Chloride, ppb 43 36 27 32 30 Sodium, ppb 18 19 20 20 15 Copper, ppb 2 7 6 2 3 Iron, ppb 12 14 6 15 20 0xygen, ppb 14 10 5 NA <2 Cation Conductivity, mhos/cm 0.626 0.984 1.15 NA <0.25 Specific Conductivity, mhos/cm 2.3 1.49 1.64 1.87 Hydrazine, ppb 14 10 19 10 pH 5.4 5.5 5.5 5.5 II Sulfate added as H 2 SO4 Silica added as Na 2SiO 3 Chloride added as hcl Sodium added as Na2SiO 3 Copper added as Cu0 (dissclved in HNO )
3 Iron added as Fe 03 4 (dissolved in PCI) ist Tank = Test duration 0 to 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> 2nd Tank = Test duration 240 to 786 hours0.0091 days <br />0.218 hours <br />0.0013 weeks <br />2.99073e-4 months <br /> 3rd Tank = Test duration 786 to 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> 4th Tank = Test duration 1335 to 1951 hours0.0226 days <br />0.542 hours <br />0.00323 weeks <br />7.423555e-4 months <br /> (3)NA = Not analyzed 0
4
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a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 26 700 680 -
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Figure 2-13. Inlet temperature.
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Figure 2-14. Outlet temperature.
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Figure 2-15. Test sample temperature near contaminated water injection point.
l 4
, The temperature of most importance is that of the test sample. The sample temperature through the first 16 days was between 530* and 535*F for more than 997, of the time. When attempts were made to raise the temperature, momentary excursions occurred to temperatures as high as 710*F. There was a single excursion to above 710*F. On one occasion over a period of 15 minutes, the temperature rose from about 600*F to 995*F before it dropped back. This occurred when contaminant water injection and heater current were re-established after an interruption.
. The parameters which are of concern because of the excursion are:
metallurgical structure, stress state, stress level, and the local environment.
This excursion had no effect on the metallurgical structure of the metal since the tubing was ;1 ready sensitized. Based on information in the Huntington Alloy Technical Bulletin for Inconel 600, the change in the residual stress state at 1000*F for if minutes is negligable.
Babcock & Wilcox ac 2 te.v. 34:e J MCOermott Company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 28 The excursion reduced the applied load tensile stress due to thermal expansion of the load train as confirmed in Figure 2-16. Environmentally, the excursion would have the effect of more quickly and efficiently concentrating the contaminant chemicals. Thus, for the short 15 minute duration of the temperature excursion, the test environment would probably be more aggressive. However, this time is only 0.01% of the total test time. Consequently, the excursion is believed to have had little or no effect on the final test results.
Af ter 16 days without achieving stable target test conditions, the target
, conditions were changed to attain stable operation. Subsequently, the sample temperature remained in the range of 520* to 527*F more than 99% of the time with no excursions above 530*F. Near the end of the test, af ter 1950 hours0.0226 days <br />0.542 hours <br />0.00322 weeks <br />7.41975e-4 months <br /> of operation, the contaminated water flow was discontinued and the temperature was intentionally allowed to rise to approximately 565'F for the last 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of the test.
This was done to dry out any deposits that may have formed on the sample.
The externally applied tensile load is shown in Figure 2-16. The sample load changed as a result of temperature fluctuations. Whenever the temperature decreased, the sample contracted and the externally applied tensile load increased. Through the test period, the externally applied tensile load ranged from 473 to 498 pounds. There was an additional hydrostatic tensile load with I the internal sample pressure of approximately 2120 psig acting against the 0.5 l inch diameter pull rod. This hydrostatic component was approximately 416 pounds, hence, the total tensile load on the sample was approximately 913 pounds.
The autoclave and internal sample pressures are indicated in Figures 2-17 and 2-18. The operating autoclave pressure ranged from 760 psig to 870 psig.
The internal sample pressure ranged from 2100 to 2190 psig. The differential
' pressure ranged from 1260 psi to 1360 psi.
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Babcock & Wilcox ac-zin v. w i a McDermot company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 29
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Figure 2-17. Autoclave pressure.
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Figure 2-18. Test sample internal pressure.
Upon completion of the 2000-hour high-temperature test, the test sample was removed from the autoclave. The lower rolled joint was sectioned off and sent to the LRC for metallographic examination. The remainder of the sample was placed back in the autoclave and exposed to simulated wet layup chemistry for three weeks. AP&L provided input and assisted with the choice of the wet layup conditions.
2.3.2.2. Operating Conditions - Low Temperature (Layup)
Upon completion of the high-temperature test, the 60 gallon stainless steel contaminant tank was drainec, flushed, and refilled with high purity water. The water was analyzed to verify that the previous contaminants were reroved, see Table 2-3. The water was then adjusted to pH 10.2 with NH 0H. The dissolved 4
oxygen concentration in the tank was increased to 102 ppb by using an oxygen-nitrogen cover gas mixture. A hydrazine addition was inen made to the l
tank. This water simulated the quality of the layup water available at ANO-1.
An analyses of the simulated layup water is shown in Table 2-3.
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- Babcock G Wit =x ** * *" '?
a McDermott company RDO:85:5233-01:01/RDD:85:5223-06:01 Page 31 o
Table 2-3 LAYUP WATER TANK CHEMISTRY (ppb)
Sample No. Chloride Sodium [lica Sulfate Oxygen Hydrazine pH Remarks 1 0.1 1 <1 2 --- --- ---
2 ---
1 --- ---
102 (2) 10.2 3 --- --- --- --- ---
156 --- (3)
II} Analysis after draining and flushing the feedtank.
Analysis after oxygen addition and pH adjustment.
I3I Analysis af ter hydrazine addition.
The layup water was then transferred to the autoclave and the vessel heated to about 150*F. Samples of the layup water from the autoclave were analyzed periodically during the three week exposure (Table 2-4). Target concentrations for sodium (425 ppb + 75 ppb) and sulfate (375 ppb + 75 ppb) in the autoclave were recommended by AP&L. Because of the high concentrations of sulfate and chloride at the beginning of the layup test, the autoclave was drained and refilled with layup water from the feedtank twice. Af ter the second refill, the levels of sodium and sulfate slowly increased during the remaining exposure time.
No chemical additions were made to the autoclave. The chemical species found in the autoclave water samples were due to leaching of these species from deposits on the surface of the test sample and from the walls of the autoclave. The sodium and sulfate concentrations of the AH0-1 wet layup water vary considerably, and they varied considerably during the autoclave test. In general, the mean concentrations during the test were lower than the means during actual ANO-1 wet layups, but consistent with test target concentrations except for low sodium.
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Table 2-4 jOi AUTOCLAVE LAYUP WATER CHEMISTRY 3#
n 3r (ppb)
[3 Se Autocla ve Specific Conductivity j$
Date Time Tempera ture. *F Sodium Sulfate Chloride Copper Iron Silica Hydrazine pH pmhos/cm Re.na rk s
=
M 09/25/84 0730 C 75 155 1.5* 59 M Autoclave filled :o with layup water, o drained and "
refilled 09/26/84 0800 75 00 422 30 Start heating the autoclave y
09/26/84 1400 155 580 455 1.1* Start layup test h exposure ..
09/27/84 0730 o 195 ---
2.2* 1.1* Dralned the auto- E clave and refilled with layup water o
09/27/84 1400 154 ---
189 13 09/28/84 0745 1/5 60 229 17 N
10/01/84 0745 177 100 373 19 w 10/09/84 1045 4
cn 159 ---
446 17 "
s-.
10/17/84 1300 161 130 530 30 13 <2 484 137 10.2 71.8 End of layup test final autoclave sample
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m___________ _ _ . _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . _ . _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __._ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _
Babcock C Wilczx nc-2 :n, m a McDermott Compar'y RDD:85:5233-01:01/RDD:85:5223-06:01 Page 33 The final autoclave water sample was also submitted for polarographic analysis to determine if any reduced sulfur species (specifically sulfide, sulfite, and thiosulfate) were present. The results of the analysis indicated that levels of th'ese species, if present, were iess than the detection limit for this method (10 ppb).
At the completion of the layup test, the test sample was removed from the autoclave and sent to the LRC for examination.
2.4 POST-TEST SAMPL'E EXAMINATIONS A series of inspections and examinations were performed on both test samples to check for cracks or other defects which may be present in either the expanded or non-expanded regions.
2.4.1 Visual Inspection and Photography A Polaroid MP-3 macrocameca and Nikon stereomicroscope were used to visually inspect and photograph the samples at low magnifications to document their appearance. The photographs in Figure 2-19 show the samples to be heavily oxidized and black in color, with some spotting due to drying of the injected contaminant solution. The side of the samples on which the pinhole was located had a heavier deposit, which appeared as if the surface had been etched. Figures 2-20 and 2-21 show additional photographs of the deposit which depict how the solution had flowed down the sample and around the lower weld. There were no cracks or defects visible on either sample.
2.4.2 Radiograohy and Penetrant Testing Each sample was radiographed at two orientations and penetrant tested on the outer surface to check for defects not visually detectable. Prints made from the radiograph negatives are shown in Figures 2-22 and 2-23. Results of both techniques showed no indications of cracking or defects in either sample.
9
Babcock O WR; x "**'* *'
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& a 5 a 0* 90 0 l Figure 2-23. Radiograph prints of 2000-hour + wet layup test sample.
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v e Babcock G Wilcrx ac 2 %. m a McDemo:t company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 42 To visually enhance the deteriorated grain boundaries, the specimen was bent inward about the tube axis and re-examined. Photomicrograph "c" was taken at the i same location as "b' and illustrates the opening of grain boundaries in the ! direction of highest tensile stress. Further inspection of the surface revealed several larger and deeper isolated grain boundary openings as shown in photomicrograph "d". These results are consistent with those obtained during the 1983 tube examination in that the tuce surface had experienced shallow IGA with j isolated cases of larger grain boundary penetrations. ~ 2.4.4.2 2000-Hour Test Sample The center and roll transition regions of the expanded portion of the test sample were examined on the outer surface. The specimens from these regions both contained a deposit dissimilar to that previously observed on the control specimen. The deposit had formed a " bubble-like" texture on the test specimens, and at higher magnifications, appeared grainy. Photomicrographs "a" in Figures 2-26 and 2-27 show this deposit and the " splits" which occurred during sleeve installation. Also visible were the circumferential surface grinding marks placed on the tube surface during manufacture. In general. the grainy deposit seemed to conform to the shape uf the surface below, while also forming bubble-like mounds. ; In order to inspect the tube surface under the deposit, attempts were made l to descale the specimens using several different solutions. Each solution used was initially tested on a piece of unused At10-1 archive OTSG tubing. To insure that the base tube oaterial was not affected, each specimen was inspected in the SEM. Inhibited hydrochloric acid was initially used. Re-examination of the specimen showed no change in the surface appearance. The next two descaling 1 f attempts used Bransonic oxide remover and Alconox, two commercial descaling solutions. Af ter each attempt, the specimens showed little change in deposit appearance. Therefore, in a final attempt, alkaline permanganate (15% tia0H + 5t KMn04 + 80%2 H 0) followed by inhibited hydrochloric acid was used. Each of the above solutions were used at 140*F in an ultrasonic cleaner. Hone of the solutions were completely effective in removing the grainy deposit. Figures 2-26 and 2-27 also show photomicrographs of the surface deposit af ter the final descaling attempt. The grainy deposit was partially removed, leaving a deposit l l I
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1 Sabcock G Wilc x ac-m xe a McDermott company . RDO:85:5233-01:01/RDD:85:5223-06:01 Page 43 similar in appearance to that observed on the control specimen. The deposit had splits similar to that observed on the free-span roll expansion samples ~) , previously examined; i.e. in the direction of highest tensile stress (4_). One instance of an isolated grain boundary opening larger than normal was observed in the expanded region and is shown in photomicrograph "d" in Figure 2-26. Since a similar opening was observed on the control specimen af ter stressing the surface ) (Figure 2-25), the opening in the expanded region may have been present prior to l exposure in the corrosion test environment. No large grain boundary openings l were observed in the roll transition region of the 2000-hour test sample, as ' l shown in Figure 2-27.
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Babcock G WilICK "*'""" A McDermoti rompany RCD:85:5233-01:01/RDD:85:5223-06:01 Page 46 2.4.4,3 2000-Hour + Wet Layup Test Sample Specimens from the rolled region of this test sample were examined and descaled in the same manner as used previously on the 2000-hour test sample. The initial inspection revealed a surface deposit which appeared typical of that observed on the control specimen. The " bubble-like" granular deposit observed on the 2000-hour test sample was not observed on the 2000-hour + wet layup test sample. Photomicrographs in Figures 2-28 and 2-29 show the surface appearance before and af ter the final descaling procedure. In the rolled region, the surface deposit had split along underlying deteriorated grain boundaries in the direction of highest tensile stress generated during sleeve installation. In the unrolled region adjacent to the roll transition, no deposit separation was observed. Photomicrographs of the unrolled region before and af ter descaling, shown in Figure 2-29, reveal the lack of deposit splitting and shallow grain boundary deterioration caused during OTSG service. 2.4.5 Metallography Transverse and longitudinal cross ssctional views were used to characterize the surfaces of the control and corrosion test specimens. An 8:1 orthophosphoric acid electroetch was used on some specimens to delinette grain boundaries. 9 e
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i wet layup test sample.
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Babcock G Wilrx nc.2 m m a McDemutt company RDD:85:5233-01:01/RDD:85:5223-06:01 Pace 49 2.4.5.1 Control Specimens i l Transverse and longitudinal views were used to examine the outer surface of l control specimens CS-A and CS-B. As photomicrographs in Figure 2-30 depict, very ( shallow intergranular penetrations were present on the specimen in the unbent i ! condition, similar to that previously observed during the free-span roll expansion project (4). All penetrations observed were 5% or less of the wall thickness in depth. 2.4.5.2 2000-Hour Test Sample The inner and outer surfaces of the tube and sleeve were transversely examined near the center of the rolled region. Three successive grind-and polish increments were performed on specimen C-2M to obtain better representation of the surface condition. The inner surface of the tube, shown in Figure 2-31 "a", was roughened due to the radiological decontamination procedure used at the LRC prior to sleeve installation. A layer of cold work and metal " folding" were observed l on the sleeve inner surface due to roller contact during sleeve installation, as l shown in photomicrograph "d" in Figure 2-31. No corrosive attack was observed on the sleeve material. Various depths of grain boundary penetrations were observed on the tube l outer surface at each grind increment. The first increment revealed slight l opening of the deteriorated grain boundaries as a result of the rolling operation l on the IGA present before corrosion testing as shown in photomicrograph "b" in Figure 2-31. The depth was less than one grain diameter and was typical of that previously observed on the free-span roll expansion samples (4_). About the same depth of penetrations was observed af ter the second grind increment, as shown in Figure 2-32. A thin amorphous-looking deposit was present on the tube outer surface and within grain boundary penetrations on the unetched specimens. Af ter etching, this deposit was not visible using light microscopy, but was verified as being present using the SEM. A subsurface defect which had penetrated - dpproximately 10% of the tube wall is shown in the "b" photomicrographs. This i 1 defect had an " island" of material in its center surrounded by the deposit which , was seen on the tube outer surface. To determine whether this defect was the tip of an axial crack, a third grind increment of 0.010 inch was taken.
l 0:bccck 8 Wilcox nc.:inev. m i
' a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 50
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I TUBE OUTER i SURFACE 100 m C S -n, Transverse Views
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M I Ih i E[ o ?$ [j i , i . 4 gr 1. 4 t *' l I . l TUdE p I
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() SURFACE ,j. Yh A Li if w I.D L bf I Ir Longitudinal Views i Figure 2-30. Photomicrographs of control specimens CS-A and CS-B.
ac 2 in.v. w e Babcock O Wilc x a McDermott company . RDD:85:5233-01:01/RDD:85:5223-06:01 Page 51 . Photomicrographs in Figure 2-33 show the results of the third grind increment. - The subsurface defect previously observed was no longer present. The amorphous-looking deposit was again visible on the outer surface and 'within grain boundary penetrations. In general, the surface appeared like that shown in Figure 2-32, with penetrations less than one grain diameter in depth. Isolated areas of penetrations approximately two grain diameters deep, were observed, however, giving a maximum observed depth of approximately 5% of the wall thickness af ter the third grind. Some of the deeper penetrations had " islands"
~
of material between grains, similar to that observed af ter the second grind. These " islands" were found to be depleted in chromium by the energy dispersive spectroscopic attachment to the SEM. The upper roll transition region (specimen UT-2M) of the 2000-hour test sample was examined for cracking using longitudinal views. Since the results were similar to those obtained from the 2000-hour + wet layup specimen described later in Section 2.4.5.3, no photomicrographs of specimen UT-2M are included here. l l I I
Babccck G Wilcox nc.2 mm me d MCC?'mC:! C,CPOJnv ROD:85:5233-01:01/RDD:85:5223-06:01 Page 52 1 l TUBE OUTER SURFACE j 100 pm "b" I l i
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n C" l - I t I SLEEVE , l I INNER , SURFACE 1 . "d" l Figure 2-31. Photomicrographs of expanded region of 2000-hour test sample - first grind. Specinen C-2i1
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Babc ck G WHc x -
"62 F" *8 a McDeemort company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 55 2.4.5.3 2000-Hour + Wet Layup Test Sample Specimens were examined from this sample in the same manner as the 2000-hour test sample. Two' successive grind iterations were performed on roll center specimen C-1M. The inner surface of the tube and sleeve looked typical of those observed previously on the 2000-hour test sample, with no corrosive attack on the sleeve. These surfaces are shown in photomicrographs "b" and "c" in' Figure 2-34 The tube outer surface was also similar to that observed previously; i.e.
slightly opened grain boundaries due to sleeve installation with isolated occurrences of deeper penetrations. Maximum penetration depth observed on this specimen was approximately 8t of the wall thickness. The amorphous-looking material within grain boundaries observed previously on the 2000-hour test sample was not observed on the 2000-hour + wet layup test sample, either prior to or af ter etching, as photomicrographs in Figure 2-35 indicate. It is not known why this material was seen in one case and not the other. However, since it was not seen af ter wet layup, this implies that it was water soluble. Photomicrographs of specimen LT-1M encompassing the lower transition region are shown in Figure 2-36. Longitudinal views showed no significant grain boundary penetrations other than those originally present prior to the corrosion
' test.
l l l i
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' a McDermott corrpany RDD:85:5233-01:01/RDD:85:5223-06:01 Page 56 3 . ,
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ac z in v. 3 84, Cchesck G Wilcox a McDermott company RDD:85:5233-01:01/RDD:85:5223-06:01 Page 57 l I 1 TUBE
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Rolled End Unrolled End I I I Figure 2-36. Photomicrographs of lower transition region of 2000-hour + wet layup test sample. Speciuen LT-lii
9 . Batscock 5 Wils!x "c2 ora mi a Mcoemon comoany RDD:85:5233-01:01/RDD:85:5223-06:01 Page 59 2.4.5.4 Unrolled Region Specimen Specimen RC was sectioned from near the bottom of the 2000-hour test sample in an attempt to determine whether significant variations in IGA depth existed
~
between the control specimens and an unexpanded region of the test sample. Transverse views of the specimen revealed no opening of grain boundaries on the outer surface other than the typical shallow deterioration of grain boundaries caused during OTSG service. Photomicrographs in Figure 2-37 appear identical to those obtained from the control specimens shown in Figure 2-30. The tube inner surface showed the layer of corrosion caused during radiological decontamination of the sample. 3.0 DISCUSSION A corrosion test was performed to determine whether the shallow IGA known to be on the outer surface of ANO-1 tubes (1) would propagate deeper into the tube wall. The test consisted of expanding a mechanical sleeve into a piece of ANO-1 tubing and subsequently exposing the sleeved tube to simylated 0TSG service.
. An earlier test (4) showed that the sleeve expansion process tends to i slightly open pre-existing IGA, in the circumferential direction, but does not
- propagate them deeper into the tube wall. Another series of tests (3) showed that sleeves rolled into sound areas of OTSG tubes form joints adequate for the expected service conditions and water chemistry.
. Evaluation of the relative depth of shallow IGA cannot be an exact t measurement because it can only be measured by destructive metallographic examination of random polished planes through the tube wall. Thus, the change in j
- depth of individual deteriorated grain boundaries cannot be monitored because the tube must be destroyed in the measuring process. It is necessary to characterize the general nature of the IGA in each individual specimen and then search for significant differences. It is not a precise testing technique but it does permit valid conclusions regarding whether significant IGA propagation did occur during exposure to simulated water chemistry.
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Orbcock & Wilrx ac um ms a McDemen comp 31y RDD:85:5233-01:01/RDD:85:5223-06:01 Page 61 The results of the examination of the various specimens from this corrosion test are summarized in Table 3-1. For comparison, the results of earlier examinations of ANO-1 tubes are included in the same table. In general, the IGA found on the corrosion specimens after testing (approximately 2% through wall) was the same as the IGA on the control specimens. Thus, the shallow IGA observed in the specimens prior to the corrosion test remained as shallow IGA after the test - there was not a general shif t' toward deeper IGA. Isolated areas of deeper IGA were found in the middle of the rolled expansions on both test specimens: 10% in the 2000-hour specimen and 8% in the 2000-hour plus wet layup specimen. However, this depth of IGA on the test specimen was no deeper than the IGA found
.on the pulled ANO-1 OTSG tube B112-119 (2% to 10% with a localized maximum of 18%, Reference ]) from which the corrosion test specimen was fabricated. Thus, the corrosion test did not indicate any propagation of IGA beyond the range observed in tubes pulled from the OTSG.
Table 3-1 EXAMINATION OF TUBES FROM ANO-1 STEAM GENERATOR Roller In Range of Depth of location of Expanded Autoclave Observed OD IGA Deepest OD IGA Control Specimens No No 2% to 5% Uniform 2000-hour non- No Yes 2% Uniform rolled (RC) specimen 2000-hour rolled Yes Yes 2% to 10%* Middle of Roll specimen 2000-hour plus wet Yes Yes 2% to 8% Middle of Roll layup specimen Original specimens No No 2% to 10% Uniform of pulled tubes Max. of 18% (Max. just (Reference 1) below #15 TSP Free span expansions Yes No 2% Uniform specimens (Reference 4)
*A thin amorphous-looking deposit was found on the OD surface and within crevices in this specimen. As it was not present af ter wet layup, it is apparently water soluble,
s Babcock G Wilmx no > mi a Mcoermon canpany RDD:85:5233-01:01/RDD:85:5223-06:01 Page 62 This corrosion test was intentionally more severe than the actual conditions expected in the steam generators. Table 3-2 lists the conservatisms. The sodium and sulfate concentrations in the faulted feedwater which was injected on the specimens in the' autoclave ranged from 2 to 6 times the expected maximum concen tra tions. This alone made the test quite conservative. The net effect of all these factors means that the water chemistry conditions used for the corrosion test are much more severe than the operating conditions expected in a steam generator. Table 3-2 CONSERVATISMS IN 2000-HOUR CORR 0SION TEST Test Condition Actual OTSG Conditions Comparison
- 1. Contaminant concentrations Nominal ANO-1 feedwater* Test was more severe ranged from 2 to 6 times nominal ANO-1 feedwater, injected directly on expanded areas
- 3. 1300 psi AP 1100 psi aP Test was more severe
*See Appendix B
**This is the average strain expected in tubes with normal variation of ID dimensions per Reference 2.
4.0 CONCLUSION
S T'he corrosion tests and subsequent metallographic examination showed that:
- 1. The SEM indicated randomly oriented outer surface intergranular penetra tions and metallography indicated a maximum depth of 5% of the tube wall on the control specimens prior to testing.
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1 Babcock O Wil=x "c2 :nm m
' McD"* " C *P'"Y RDO:85:5233-01:01/RDD:85:5223-06:01 Page 63
- 2. The 2000-hour specimen revealed axially oriented outer surface intergranular penetrations in the center of the expanded areas under SEM examination. The maximum depth of penetration found was 10% of the wall thickness. No grain boundary attack was observed in the i
roll transition regions other than that typically observed on control speicmens. A thin amorphous-looking deposit was observed on the entire OD surface and within grain boundary separations.
- 3. The 500-hour wet layup specimen revealed axially oriented outer surface intergranular penetrations in the center of the expanded areas similar to those seen in the 2000-hour specimen. The maximum j depth of penetration found was 8% of the wall thickness. No grain boundary attack vas observed in the roll transition regions other than that typically observed on control specimens. The amorphous-looking deposit was not evident af ter wet layup.
- 4. Examination of the unexpanded portion of the 2000-hour corrosion test specimen appeared identical to the control specimens which were not in the autoclave.
4
- 5. Although isolated grain separations of up to 10% of the wall
- thickness were seen, the preponderance of data from the 2000-hour corrosion test and the 500-hour wet layup test indicate that the general surface codition (consisting of shallow 2: IGA) tha t wa s found af ter the test also existed in the control specimens prior to the ?.e s ts. The corrosion test did not indicate any propagation of 4
IGA beyond the range observed in tubes pulled from the OTSG. ! 6. An unusual crack morphology was found on the 2000-heur corrosion
- test specimen. The large penetrations had an island of material in j the center surrounded by an amorphous-looking deposit.
In summary, the corrosion test showed essentially the same depth of IGA in specimens removed from the autoclave as found in specimens examined prior to the te s t. This test was intentionally conservative compared to the actual service environment expected a t ANO-1. Thcrefore, we conclude that this test, in conjunction with the information contained in the referenced reports, support the installation of the mechanical sleeves in the ANO-1 OTSG's. p
,ll. f . p d L T J. V. Monter
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C. Inman k. D. W. Kgch Attachmen ts
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_e REFERENCES
- 1. S. C. Inman, " Examination of 0TSG Tubes B73-8 and B112-19 from ANO Final Report," Babcock and Wilcox letter Report RDD:84:5303-04:02, June,1983.
- 2. R. J. Beauregard and S. C. Inman, " Qualification of OTSG Tube Decontamination Technique," Babcock and Wilcox letter Report RDD:85:5223-02:01, October 2, 1984, p. 5.
- 3. "Once-Through Steam Generator Mechanical Sleeve Qualification," Babcock &
Wilcox BAW-1823P, June, 1984
- 4. S. C. Inman, "The Effects of Roller Expanding Sleeves Inside OTSG Tubes Affected by Intergranular Corrosion," Babcock and Wilcox letter Report RDD:85:5290-03-00:01, February, 1984.
i
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8 _ _ _ . _ _ _ _ _ _ . _ _ _ _ . . _ _ _ _ . _ _ _ _ _ . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - " - - - ' - - - - - - - - - - ' - - ' - - ^ ^ - - ' - - - - - - - - - - - ^ ^ - ~ ~ ~ ' ^ - ~ ^ - - - - - - - - - - - ^ ' - - - - ~~ ^^ ~ ~ ~
g,. . APPENDIX A Procedure for Installation of a Roller Expanded Sleeve Inside an OTSG Tube 9
a. APPENDIX y En9fneerin Information Recorg s
go BWNP-20440-2 (10 93 ) BABCCCK & WILCCX - UPGC ENGINEERING INFCRMATICN RECORC Safety Relatea: 00CUMENT IDENTFIER 51 - 1152777-00 YES O NO O TITLE BASIS FOR CORROSION TEST CONTAMINANT CONCENTRATIONS PREPARED BY D. W. K0CH h M b /" DATE 6M
/
REVIEWED 8Y J. H. HICKS - OATE I 2 /[N REVARKS-
! This document presents the technical basis, including calculations for the con-taminant concentrations to be injected into an autoclave test of an ANO-1 OTSG tube that has a mechanical sleeve installed in it. The contaminant concentrat-l ions were selected to give nearly equivalent quantities of contaminants that j typically enter the AN0-1 steam generators via the feedwater in the same time
. period.
I l BASIS FOR CORROSION TEST CONTAMINANT CONCENTRATIONS I i A corrosion test of an OTSG mechanical sleeve design shown in Figure 1 is being I conducted to detemine if a sleeve of this design will propagate the existing intergranular attack (IGA) in the AN0-1 GTSGs. The corrosion test environment l 15 desired to be typical of the ANO-1 OTSG operating environment. In view of l this a study was made of the ANO-1 f?edwater chemistry data for a 2-year period 1 from August, 1981 through August, 1983. In order to establish the normal operating environment, a criterion was selected to determine the value for which I 90% of the data for each parameter was either equal to or less than. The results
. of the stuoy were as follows:
Table 1 - ANO-1 Feedwater Chemistry _ , parameter 90% of Data Sodium 1 2.0 ppb Chloride 1 4.6 ppb Silica 1 4.0 ppb Sul fate
- 1 5.0 ppb Iron 110.0 ppb Copper 1 1.5 ppb Cation Conductivity 1 0.2 u mhos/cm pH E 8.8 1 9.2
- Data limited to period of May,1983 through September,1983
. f*H t et .A
- s-
. 51-1152777-00 Page 2 of 3 The above values were used to calculate the amount of sodium, chloride, silica and sulfate that would transported into a steam generator in 2 2000-hour period, i.e. the planned test period. The calculated amounts of each were then converted to a unit area basis. With a planned injection rate of 4 ml/ min., the concen-tration for each specie in the contaminant solution was calculated that would give an equivalent quantity per unit area on the test specimen. A sample cal-culation for the sodium contaminant follows:
- 1. Calculate the amount of sodium introduced to an OTSG per unit area of tubing during a 2000-hour period:
6 w= 5.56 x 10 #/hr No.ofTubes=15,5y1 CNa= 2 x 10 ma/#H O 2 S.A./ Tube = 1225 in 6 Wt. of Sodium - 5.55 x 10 #/hr x 2 x 10-9 x 2000 hours Wt. of Sodium = 22 # or 10,000 grams ' 1 9
} tubes
= 0.64 grams /tuk
= 0.00052 grams /in 2 2 in 2
- 2. Calculate the concentration of sodier, required in test contaminant solution to provide equivalent amount of sodium on the surface of the parent AN0-1 tubing test specimen:
Injection Rate = 4 ml/ min = 240 grams of solution / hour Test Time = 2000 hours Specimen = 13.7 in 2 Surface Area
= 2 2 C
Na 0.000529/in 2IO g/hr x 2000 x 13.7 hr in = 14.8 x 10-9 or
'14.8 ppb Similar calculations were performed for the chloride, silica, and sulfate species and the calculated concentrations for the contaminant solut. ion were 34, 31 and
'37 ppb, respectively.
An attempt to equate the calculated weights entering the OTSG per unit area of tubing with actual measured deposit weights was unsuccessful. The only data that was found for ANO-1 tubing deposits was for sulfur, which, when put on a sulfate basis per unit area, resulted in a value that wag approximately a fagtor of 30 less than the calculated value; i.e. 0.000046 g/in versus 0.0013 g/in . From this it was apparent that a direct correlation between the calculated values and actual deposit weights did not exist, at least for sulfate. Nevertheless, it was believed by both B&W and AP&L cognizant engineers that the l method of calculation described above represented a reasonable basis for establish-ing a relationship between the OTSG operating environment and the corrosion test environment.
, s.
CY ' . . _ . . - 51-1152777-00 Page 3 of 3 After a review of the calculated values, AP&L requested that the chlcride, silica and the sulfate values be rounded to 30 ppb and the sodium value be rounded to 15 ppb for the test contaminant solution. These were chosen as target values and it was realized that actual test values could be somewhat higher or lower. In any event the projected contaminant concentrations are reasonable approx-imations of the operating 0TSG environment. The iron and coppar contaminant concentrations were arbitrarily selected at I two times the ANO-190% values listed in Table 1; i.e. 20 ppb and 3 ppb, respec-tively. The nominal contaminant levels to be used in the corrosion test are tabulated as follows: Table 2 - Test Contaminant Concentrations . Chemistry Parameters Concentration
- Sodium 15 ppb Chloride 30 ppb Silica 30 ppb
, Sul fate 30 ppb Iron 20 ppb Copper 3 ppb The water to be used to prepare the contaminant solution will be deaerated I
and demineralized. The sulfate and chloride will be added as the acids and silica will added as the sodium salt due to stoichiometric considerations. 1 l l i}}