ML20235A310

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Insp Browns Ferry Nuclear Plant Unit 2 Evaluation of Feedwater/Condensate Piping for Erosion/Corrosion Damage
ML20235A310
Person / Time
Site: 05000000, Browns Ferry
Issue date: 06/10/1987
From: Fox J, Wods T
TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML082420107 List:
References
NUDOCS 8709230270
Download: ML20235A310 (87)
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Text

{{#Wiki_filter:_ _ _ _ _ _ _ _ - _ _ - _ _ - 9 INSPECTION l BROWNS FERRY NUCLEAR PLANT UNIT 2 EVALUATION OF FEEDWATER/ CONDENSATE PIPING FOR EROSION / CORROSION DAMACE /Ak7 Prepared by: N. Date Sub:nitted by: M Data d /O S# 2281U 8709230270 970918 PDR ADDCK 05000259 G PDR

1 i BACKGROUND On December 9, 1986, Surry Station Nuclear Plant experienced a pipe rupture on the unit 2 feedwater/ condensate system. The unit was operating at 100-percent power before the rupture. The rupture occurred in the 18-inch suction line to the "A" main feed pump. The failure was in a 90-degree elbow approximately one foot downstream of a tee from a 24-inch header and resulted in complete separation and dislocation of the suction line. The heated, pressurized water in the system flashed to steam as it discharged from the severed pipe into the Turbine Building, engulfing personnel and equipment in the area. Eight individuals in the immediate area were burned by the steam, six seriously. The injuries to four of these individuals subsequently proved fatal. The ( failure was identified as wall thinning resulting from erosion-corrosion (EC) { damage. ] EC is characterized by dissolution of protective magnetic film by a high-temperature liquid stream in contact with steel surfaces. Factors influencing the EC mechanism are: 1. pH and water.nd/or steam chemistry, 2. material composition, ) 3. flow path geometry, { j 4. velocity, and j 5. temperature. ) OBJECTIVE l As a result of the catastrophic failure at Surry, inspection programs were i developed for Sequoyah Nuclear Plant (SON) and Browns Ferry Nuclear Plant (BFN) to address wall thinning in the single-phase flow regime. Inspections had previously been performed at each plant to address EC in dual-phase flow j piping. These inspections, in some instances, resulted in replacement of j localized thinned areas with a more EC-resistant material, j ) The development of programs to address single-phase flow EC in the feedwater/ j condensate system at each plant was based on the following parameters: 1. An established temperature boundary. 2. Flow velocity at specified locations. 3. Flow path geometry (i.e., Kellers Geometry factors). 4. Distance between fittings (i.e., less than 10-pipe diameters apart). Other parameters, such as material composition and water chemistry, were fixed variables throughout the system. The laspection program for SON has beter completed and the results are given in the memorandums from D. W. Wilson to E. L, Abercrombie.Cated January 27, 1987 (B25 870127 028) and April 8, 1987 (B25 870408 067). Based on the SON results, industry experience, and research data, an inspection program was then developed and implemented for BFN to address single-phase EC damage. 2281U

l I ( DISCUSSION Thirty-two areas were s' elected on the BFN unit 2 feedwater/ condensate piping to examine for wall degradation. Grids were placed on select circumferential, intrados,' and extrados portions of fittings to assess existing pipe wall conditions. Ultrasonic test (UT) methods were employed to measure wall i thickness and all UT was performed by the In-Service Inspection Group (ISI) in accordance with N-UT-26. The piping and fittings were identified from the I bill of material as ASTM A106 Grade B and ASTM A234 Grade WPB, respectively, and the 30-inch main header was identified as ASTM A155, Grade KC-70, Class 1. The boundary conditions for this inspection were a temt stature range of 2500F to 4000F and linear velocity ranging from 6 to 12 ft/sec. Flow path geometry was also incorporated into this evaluation based on Kellers' factors at specified locations. The majority of the fittings examined were within 10-pipe diameters of the next closest fittings as recommended by EPRI. The inspection boundary is shown in the attached heat balance diagram (Figure 1). The areas within this boundary are considered to be the highest suspect areas for EC damage in the feedwater/ condensate system. l Of the 32 areas initially targeted for inspection, UT results could only be obtained on 28 of these areas. The 4 areas where UT methods could not be employed were at the suction and discharge soool eleces of the "A" and "C" reactor feed pumps. The level III NDE engineer stated that no backwall echo was obtainable in these locations, which indicates the probability of nonparallel inner and outer surfaces. Parallel surfaces are a prerequisite for UT wall thickness examinations. Inspection of the identical location on the discharge of the main feed purp at SQN showed some evidence of minor thinning that was believed to have resulted from cavitation damage. Although 3-percent wall reduction was noted, the minimum wall acceptance criteria for the fitting had not been violated. Evaluation of the data from the 28 remaining areas did not show any evidence of wall degradation. All but one of the remaining wall thickness values exceeded the manufacturer's minimum wall value (see Grid 19, Table 1) for the respective diameters and pipe schedules, and the majority were above the nominal vall thickness values. The one data point was located on the 30-inch portion of the 30- x 18-inch reducing tee, approximately 10 feet upstream of the C2 feedwater heater. The measured wall thickness at this location was less than 0.5 percent below the manufacturer's minimum wall value. The results at BFN are consistent with industrywide experience for BWR water chemistry in the single-phase flow regime. Erperience has shown that, although the pH of a PWR system is higher than that of a BWR, the significantly higher dissolved oxygen content in a BWR system provides a more stable protective magnetite film that.-greatly retards EC. in the single-phase flow regime. 1 Attached in Table 2 is a brief description of the areas. selected for this } UT evaluation. Also attached are photographs of representative grids and I Appendix A which contains sketches and supplemental informar, ion used in f developing this inspection program, j l 2281U l I l 1 )

I o 1 ~ CONCLUSION AND RECOMMENDATIONS The results from the UT evaluation demonstrated that EC damage has not occurred j in the areas examined. The areas selected are representative of the highest I suspect areas in the feedwater/ condensate system. Based on these findings, industry experience, and the BNR water chemistry in the single-phase flow regime, EC is not believed to be a significant problem in the BFN feedwater/ condensate piping. However, we are recommending that a visual inspection be performed on the spool pieces immediately upstream and downstream of the "A" I and "C" reactor feed pumps since UT methods were unable to measure existing pipe l wall thickness. Also, a formal surveillance program should be established for l select single-phase flow piping areas in the feedwater/ condensate system to l monitor and determine if any appreciable wall degradation has occurred during I operation. This program should be extended to include potential EC of the I turbine building heater drains and vent lines. I In addition, an independent technical evaluation by an outside contractor will be performed on our inspection program for each unit before their respective startup. This evaluatian is being conducted to provide additional assurance that all potential problem areas are being addressed. 2281U i i \\

p o TA8LE 1 BROWNS FERRY NUCLEAR PLANT-FEEDWATER/ CONDENSATE PIPING WALL THICKNESS DATA Nominal Mfg. Min. Minimum Detected . Diameter Thickness Wall Thickness Value Grid Wumber (Inch) (Inch) (Inch) (Inch)' 1 18 0.438 0.383 '2 18 0.438 '0.383 0.640 3 18 0.438 0.383 0.590 l 4 18 0.938 0.821 5 18 0.938 0.821 0.960 6 18 0.938 0.821 1.000 7 18 0.438 0.383 8 18 0.438 0.383 0.610 9 18 0.438 0.383 0.620 10 18 0.938 0.821 11 18 0.938 0.821 1.020 12 18 0.938 0.821 1.110 13 18' O.938 0.821 0.980 14 18 0.938 0.821 1.120 15 18-0.938 0.821 0.900 16 20 1.031 0.902 0.920 l 17 18 0.938 0.821 1.100 l 18 18 0.938 0.821 1.040 19 30 I 18-

    • /0.938 1.125/0.821 1.120/0.840 20 18 0.938 0.821 1.000 21 18 0.938 0.821 1.080 22 20 1.031 0.902 1.020 23 18 0.938

~0.821 1.100 24 18 0.938 0.821 1.000 25 18 0.438 0.383 0.550 l 26 18 0.438 0.383 0.510 27 18 0.438 0.383 0.510 I 28 18 0.438 0.383 0.530 1 29 18 0.438 0.383 0.510 30 18 0.438 0.383 0.480 31 30 I 18

    • /0.938 1.125/0.821 1.300/1.120

} 32 18 0.938 0.821 0.900

  • No backwell echo was obtainable in these grids. This indicates the
  • probability'of nonparallel inner and outer' surfaces. No manufacturer's

~ drawings were available for further investigation.

    • Nominal thickness not specified.

l 1 4 2281U ___.__________J

TABLE 2 TABLE 1: IDENTIFYING GRID LOCATION AND FITTING TYPE Grid No. Type of Fittints Location 1 18-inch, Sch. 30 Spool Piece Immediate Suction of 2A Reactor Feedwater Pump 2 18-inch, Sch. 30, Elbow Approx. 6 feet on Suction side of 2A Reactor Feedwater Pump j i 3 16-inch, Sch. 30 Elbow Approx. 6 feet on Tvetion side of 2A Reactor Feedvatar Pump 4 18-inch, Sch. 80 Spool Piece Immediate Discharge of 2A Reactor Feedwater Pump 5 18-inch, Sch. 80. Elbow Approx. 6 feet on Discharge Side of 2A Reactor Feedwater Pump 6 18-inch, Sch. 80 Elbow Approx. 6 feet on Discharge Side of 2A Reactor Feedwater Pump 7 18-inch, Sch 30, Spool Piece Immediate Suction of 2C Reactor Fesdwater Pump 8 18-inch, Sch. 30. Elbow Approx. 6 feet'on Suction Side of 2C Reactor Feedwater Pump 9 18-inch, Sch. 30. Elbow Approx. 8 feet on Suction Side of 2C Reactor Feedwater Pump 10 18-inch, Sch. 80, Spool Piece Immediate Discharge of 2C Reactor Feedwater Pump 11 18-inch, Sch. 80, Elbow Approx. 6 feet on Discharge Side of 2C Reactor Feedwater Pump 12 18-inch, Sch. 80. Elbow Approx. 6 feet on Discharge Side of 2C Reactor Feedwater Pump 13 18-inch, Sch. 80, Elbow Approx. 10 feet Upstream of 2A2 Feedwater Heater 14 1,8-inch, Sch. 80 Elbow , Approx. 6 feet Upstream of 2A2 Feedwater Heater 15 18-inch, Sch. 80, Elbow AppEox. 2 feet Upstream of 1A2 ~ Feedwater Heater i 16 20-inch, Sch. 80. Elbow Between 2A1 and 2A2 Feedwater Heaters 2281U

L TABLE 2 (continued) TABLE 1: IDENTIFYING GRID LOCATION AND FITTING TYPE 4 Grid No. Tree of Fittinas Location 17 18-inch.-Sch. So, Elbow Approx. 2 feet on Discharge Side of 2A1 Feedwater Hester l 18 15-inch, Sch. 80. Elbow Approx. A feet on Discharge Side of 2A1 Feedwater Heater I-19 30-inch x 18-inch Tee Approx. 10 feet Upstream of 2C2 Feedwater Heater 20 18-inch, Sch. 80. Elbow Approx. 6 feet Upstream of 2C2 Feedwater Heater 21 18-inch, Sch. 80 Elbow Approx. 2 feet Upstream of 2C2 Feedwater Heater l 22 20-inch, Sch. 80, Spool Piece -Between 2C1 and 2C2 Feedwater Heater 23' 18-inch..Sch. 80 Elbow Approx. 2 feet on Discharge Side I of Feedwater Heater 24 18-inch, Sch. 80, Elbow Approx. 4 feet on Discharge Side of 2C1 Feedwater Heater 25 18-inch, Sch. 30 Elbow Approx. A feet Downstream of 2A3 Feedwater Hester 26 18-inch, Sch. 30. Elbow Approx. 8 feet Downstream of 2A3 Feedwater Heater 27 18-inch, Sch. 30, Elbow Approx. 4 feet Downstream of 2B3 Feedwater Heater 28 18-inch, Sch. 30, Elbow Approx. 8 feet Downstream of 2B3 I Fendwater Heater 29 18-inch, Sch. 30. Elbow Approx. 4 feet Downstream of 2C3 Feedwater Heater 30 318-inch, Sch. 30, Elbow Approx. 8 feet Downstream of 2C3 Feedwatec Heater 31 30-inch x 18-inch Reducer Approx. 20' feet Upstrezm of 2A2 Feedwater Heater l l 32 18-inch, Sch. 80, Piping Approx. 20 feet Upstream of 2A2 4 Feedwater Heater } 22810 i

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APPENDIX A l l I f t 2281U i

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, F." FACTOR DATA FROM PH. BERGE (EDF) FEBRUARY 8, 1984 jg . INFLUENCE DE LA GEOMETRIE Facteur de correction.ke (d'apr6s KELLER) 1 WU - M/NN/e g 1 kc'=1 ke=1 ke=1 ke=0,75 WE h. h ke=0,6 ke = 0,52 ke = 0,3 ke = 0,23 wi- - - /a w--/-N//, .d - s wa-Ni-, u. m,-. W"####4 i ("##' ke = 0,15 ke =0,15 ke =0,16 ke =0,04 - j,,_ w 7_. ~ kc = 0,16 & 0,24 Pour un coude : kc 0,367 R m'... D J avec J R rayon moyen D diambtre interne du coude e is o-ie

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9 2'*d 10101 2 'd LE:11 LB/CO/20 01Nd110-2*D3M WOMd Revised 1/30/87 Thinning of Secondary Piping Roquest for Information From the Regions 1. For PWRs and BWRs, identify which licensees have and which licensees have not prepared programs to determine whether their large-diameter steam, A, feedwater, condensate, and connected system piping is subject to thinning of M/ the piping wall. 7 2.. Piping for those systems is subject to wall thinning if the following. conditions exist: (a) Carbon steel fittings and spools. ~ (b) Fittings less than 10 pipe diameters apart. (c) Bulk flow greater than 10 feet per second. (d) Fluid temperature between 195 and 440 degrees F. (e) Oxygen concentration less than 600 ppb.[ Determine whether licensees have included these factors in their programs. If other factors have been included, identify them. 3. Determine how many measurements will be taken and where they will be taken. 4. If measurements have been taken, provide the results. CONTACTS: Jack Rosenthal, (301) 492-4193 Rogerr Woodruff, (301) 492-7205

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==o:Ae an is e o Corrosion Rates and Release Rates for Carbon Steel at Different Oxygen Concentrations for 1,000 hr Exposure Times at Temperatures in the Range 200-300*C,(392-572*F). s00 H1NC - = = = = = =

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/ o_____--- g ,00 g i e 200 I 8 Q 200000 02 """'y""'**"*""'"*""'""""""'""'*==*==="""*""'""**""'"'""*""*""*""""""""**** 100 '== h - ad== M - - -- d ] . +. I O 0 2 4 g 5 to 12 14 16 a j ,g l k en .EXPoSU. ME TIME (montasi ~ Corrosion of Carbon Steel SA333-6 in HWC and the Reference Environment. 1

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MemorandMM TENNESSEE VALLEY AUTHORITY Ei25

'87 0 L 2 7 0 2 a ~ H. L. Abercrembie, Site Director, 'ONP, O&PS 4, Sequoyah Nuclear Plant To D. W. Wilson, Project Engineer,-Sequoyah Engineering Project, DNE, DSC-E, FROM Sequoyah Nuclear Plant DATz JAN 2 71987 SUBJECT. SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 - PRELIMINARY REPORT ON THE CONDENSATE-FEEDWATER PIPING INSPECTION -' SUSPECTED EROSION-CORROSION AREAS Attached-for your review is the preliminary report of SQN' condensate-feedwater inspection. The results indicate that there is no wall thinning. due to erosion-corrosion. However, there may be minor (three-percent wall thinning) cavitation damage on the discharge piping of A and B feedwater pumps. The remaining wall in that area has not been reduced below the minimum design wall thickness. Appropriate surveillance instructions shall be written to monitor the suspect areas. The instruction will be written by Operations Engineering Services' metallurgical employees and is expected to be in place by June 30, 1987. The final report will include the results of ultrasonic examinations' of the. elbows downstream of A and B pump and will be issued the week of February 6, 1987. I bb ~. D. W. Wilson [AttachmentLh RBfD G: oc (Attachment): I RIMS. SL 26 C-K M. J. Burzynski, ONP, O&PS 4. Sequoyah j J. C. Key, DNE, DSC-E, Sequoyr.h s 1 J. H. Sullivan, ONP, SB-2, Sequoyah N., B. M. Patterson, ONP, P08-2, Sequoyah (Attn: E. L. Bo'oker)g Principally Prepared By: Robert L. Phillips and Terry R. Woods, } extension 6946 4

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SEGUOYAH' NUCLEAR PLANT UNITS 1 AND 2 - PRELIMINARY REPORT ON CONDENSATE- ~FEEDWATER PIPING INSPECTION - SUSPECTED EROSION-CORROSION. AREAS

References:

1. D. W. Wilson's memorandum to H. L. Abercrombie dated December 19, 1986, "Sequoyah Nuclear Plant Units 1 and 2 - Inspection of Feedwater Piping for Wall Loss" (B25.861219 001) 2. Report by'P. Berge and F. Khan, of Electricity de France, l dated May 1982, " Corrosion Erosion of Steels In High Temperature Water and Wet Steam" 3 EPRI NP 3944 report, " Erosion / Corrosion in Nuclear Plant-Steam Piping; Causes and Inspection Program Guidelines" l r

Background

On December 9,'1986, Surry Station Nuclear Plant had a pipe rupture on the condensate-renwater system that caused several. fatalities. The rupture was caused by localized wall thinning at a pipe-to-elbow weld. The tMnning mechanism was identified as erosion-corrosion (EC). Sequoyah Nuclear Plant'(SGN) implemented a program to identify possible EC damage (see reference 1). ~ The program was developed from technical information from Surry Station, INPO network, regional and resident NRC inspectors, and information from references 2 and 3 EC is characterized by dissolution of protective angnetite film by a high temperature liquid stream in contact with steel surfaces. EC damage is normally found in elbows on the extrados (outer radius); however, it'may also be seen on the intrados (inner radius). The phenomenon is usually observed in plain carbon and low alloyed steels at elevated temperatures.- The following are factors influencing the EC mechanisms. 1. pH and water and/or steam chemistry 2. Material composition 3 Flow path geometry 4. Velocity 5 Temperature ' Incorporating the' above factors and experience from Surry Station, a temperatur, boundary of 300 to 400 degrees Fahrenheit was established for initial inspection. These areas were considered to have'the highest probability of damage. The locations inspected are identified in figures 1, 2, and 3 Surry and SQN both used ASTM A106 Grade B piping and fittings on the r feedwater system. The plants also had similar operating parameters at the l time of failure (i.e., water chemistry). The piping that failed had

i E 1 I l. thinned' from 0 500 inch (nominal wall) to 0.060 inch. SCN has schedule 40 { . piping (nominal' wall.688 - minimum wall.602). The rupture at Surry. .l occurred at the 'feedwater pump section at a' spool-piece and.a 90-degree elbow.- SQN has a spool-piece and 45 degree elbow, which has a less severe geometry factor. 'SQN's feedpump section elbow and spool-piece and the suspect areas adjacent to the A and B pumps were selected for inspection. l- ' ) Objective The purpose of this report is to: 1. Identify possible thinning. 2. Determine if thinning had exceeded the minimum wall thickness.

3. ' Recommend corrective action.

4. Write, as necessary, preventative maintenance (PM) and/or surveillance ~ instructions (SI) to trend degradation. The inspection plan employed ultrasonic (UT) and metallurgical inspection methods. All.UT was performed.in accordance with TI-51, N-UT-26. The i Inservice. Inspection Oroup (ISI) performed the UT. The metallurgical inspections were performed by Operations Engineering Services-(CES), Welding.and Metallurgy Section and utilized flashlights and visual aids. Both inspect! ion methods will identify EC damage as intermittent ID surface grooving and gouging. Visually, EC would be seen as intermittent removal of the black magnetite flim exposing either bare metal or red hematite. Results and Discussion E The UT was performed on the suspect pipe OD surfaces on selected elbow extradose and intradose utilizing 4-by 4-inch grids to identify the examination. Each grid was evaluated, and the maximum and minimum readings were' recorded. Oross differences in the high and low reading were noted and evaluated by ISI and OES. Figures 4 through 28 show the typical inspection method, practices. i The piping and fittings were schedules 40 and 80. Although the fittings do not have a standard nominal wall, they are manufactured to a minimum thickness in accordance with ANSI B16 9,16.11, and 16.28. The minimum for each size and schedule was calculated (see, tables 1 and 2). This minimum was used as a baseline. Readings below the minimum would indicate thinning. i 9 O e W

' q The UT data was uniform and consistent and indicated that there was no thinning occurring as a result of EC, which would appear to be localized areas of non-uniform thinning. With one exception, there were no readings below the minimum thickness established in accordance with ANSI specifications. Wall thickness measurements taken on the discharge side of the feedwater pump on a 24-by 16-inch reducing elbow (Crid 2-FW-9) showed some evidence of wall loss. This wall reduction is believed to have resulted from cavitation damage because of the large pressure drop that exists at that location. Although three-percent wall reduction was notec, the minimum wall acceptance criteria for this fitting hac not been violated, and this area will be monitored for wall reduction in the future. The Division of Nuclear Engineering (DNE) had provided a design minimum acceptable wall thickness for the areas identified for the analysis (see tables 1 and 2). The inspections showed that no reading was below these values. Metallurgical Insoection Metallurgical inspections were performed on A and C trains of units 1 and 2 number 2 feedwater heaters. The locations are shown on figure 16. Both the inlet and discharge piping and fittings were inspected. The inlet piping had some superficial patterns on its wall because of direct impingement from the number 3 heater drain tank piping. No red hematite was observed on th'e ID, and the black magnetite film was intact (see location 3, figur,e 16). At location 2, no red hematite, or exposed base metal was observed. On the discharge piping, the results were similar. Also, there was a backing-ring that had been pushed into the flow path during original installation. It showed no signs of wear and was covered with the protective magnetite film, even though it was in a severe environment. Discussion UT and metallurgical inspections indicated that no EC damage or significant thinning by other means was detected, although SQN has conducive feedwater piping conditions. However, SQN has maintained good feedwater chemistry, which lessens the probability of failure and/or EC damage. The history of the feedwater chemistry at Surry Station is unknown. Pravious inspections on the number 3 heater drain tank, the steam generator feedring header, and the feedring tee did not reveal service-induced. damage. EC damage was observed on the feedring J-tubes. (The J-tutas were A106 Crade B steel, but the velocities were as high 31 ft/sec.) Velocity of the 24-and 30-inch headers and fittings were I j 12 ft/sec and 14 ft/sec respectively (see, table 3). The propensity of the EC dec~reases with a decrease in velocity. 3 y i l l

r, 4-l Conclusions and Recommendations The test data' and inspection results indicated that EC damage had not j occurred in the areas examined. The selected areas were identified as the 3 highest probability areas. However, there may be other thinning mechanisms occurring, i.e., cavitation. The lowest readings were-found on the discharge side of the feedwater pump on 24-by 16-inch reducing elbows. None. of these readings were below the design minimum wall thickness .specified by DNE. The elbows.further downstream of the A and*B pumps will be examined and inc1' ded in the final report..The piping upstream of the u pumps is acceptable but should be monitored by an SI each refueling outage. Feedwater pH should be optimized to the highest pH attainable to minimize the potential for EC. damage throughout the balance of the plant carbon steel system. A study to optimize the SQN pH has been initiated by the Chemical Engineering Unit. RLP:HC 1/26/87 HC7017.01 S O O 4 e 4 I 4 i l

asco d aat n l i eepn 1 1 1 1 1 mseo ~ 1 1 1 1 1 1 1 mURM oc e) ) ) R1 23 s tnemmo C sse ) ngs 0 0 0 0 0 0 0 0 0 0 0 0 k ne 4 2 6 3 4 3 6 4 0 4 6 8 cih 7 6 7 8 7 7 6 7 7 5 5 1 id c h an 1 TeIR( T U m ue ml ) 0 2 3 2 3 1 i b s 3 6 5 6 5 nal e 0 0 5 5 3 0 0 0 5 3 2 2 E itl h 3 3 3 3 3 4 4 L Mpac 5 5 / / / 5 5 5 / / B eWn 4 4 3 8 0 8 0 A E c I 6 4 3 4 3 T N c ( DA 6 8 5 8 5 y mum ) 2 8 7 8 7 i s 0 3 3 3 3 nl e 2 2 6 7 4 2 2 2 7 4 0 0 il h 0 0 0 0 0 2 2 Mac 6 6 / / / 6 6 6 / / 5 5 Wn 6 6 2 6 2 R I 5 6 0 6 0 P ( H 6 0 6 0 6 1 1 e gl 9 nu 6 id 0 0 0 0 0 0 0 0 0 0 0 0 t e 4 4 4 8 4 4 4 4 8 4 4 4 B 1 th ic FS I SN A y z) b e [ d is a a 6" 6" a e Se 4 6 6 i h 2 1 1 gc f 1 1 a a a a i nn 4 4 x x x 4 4 4 x x 0 0 c iI 2 2 2 2 2 2 2 e t( a t p 0 4 4 4 4 s iD 3 2 2 2 2 FO mu m 0 1 2 i 1 2 3 4 5 6 7 8 9 1 1 1 n i d. W W l W W H W W W W W M l i i o F F F F F F F F F F F F i rN G 1 1 1 1 1 1 1 1 1 1 1 1 1 l

n l i eepn mse o 1 1 1 i i 1 1 1 3 1 1 1 mURH c o e) ) ) R1 23 w w w o o ow b b b o 1 l l l gc ge gee n n n b i" d6 d 6" i i " d6% m s a1 a1 a1 3u t e e e m n rn rn rnsi e o o oan m t t t wi m sd sd sd m o en en ens C wu wu wuiR oo oo oohE Lf tr LfTH s sse ) ngs 0 0 0 0 0 0 0 0 0 0 0 0 k ne 8 2 6 5 8 1 1 0 2 7 0 8 cih 6 6 7 5 6 7 6 7 7 6 6 5 id c h an TeI R( TU m ue ml ) 0 3 2 2 3 2 ib s 3 5 6 6 5 nal e 0 0 5 3 5 0 0 0 5 3 E itl h 3 3 2 2 3 3 3 4 4 L Hpac 5 '5 / / / 5 5 5 / / B eW n 4 4 3 0 8 8 0 A E c I 6 3 4 4 3 T N c ( DA 6 5 8 8 5 y mum ) 2 7 8 8 7 i s 0 3 3 3 3 nl e 2 2 6 4 7 2 2 2 7 4 0 0 il h 0 0 0 0 0 2 2 Hac 6 6 6 6 6 / / / / / 5 5 W n 6 2 6 6 2 R I 5 0 6 6 0 F ( H 6 6 0 0 6 1 1 e gl nu id 0 0 0 0 0 0 0 G 0 0 0 0 t e 4 4 4 4 8 4 4 i 8 4 4 4 t h f i c PS ez) i s 6" 6" 6" S e 4 6 h 2 1 1 1 1 gc 0" 0" nn 4 4 x x x 4 4 4 x x i I 2 2 2 2 2 2 2 t( t 0 4 4 4 4 i0 3 2 2 2 2 F 0_ 0 1 2 1 2 3 4 5 6 7 8 9 1 1 1 d. W W W W W W W W W W W W i o F F F F F F F F F F F F rf l G 2 2 2 2 2 2 2 2 2 2 2 2

I '~ TABLE 3 Original mass flow rate: 15,705,450 lbs/hr l 1 Conversion Factors 1 hr = 3600 see i 3 1 ft = 7.48 gallons 1 gallon 3 8 337 lbs calculation 3 3 15,705,450 lbs x 1 he x 1 ft x 1 gal = 69 96 ft/ 3,c 1 hr 3600 sec 7 48 gal 8,337 lbs Yelocity Mass flow rate Pipe radius = 15 inches or 1.25 feet cross seccional area 3 Velocity = 69 96 ft /sec 14.25 ft/sec for 30-inch = 4 909 ft Assume mass flow rate equally divides into two 24-inch pipes. New mass flow rate = 7,852,725 lbs/hr Pipe radius 12 inches of 1 root 3 3 7,852,725 lbs x 1 hr x 1 ft x 1 gal = 34 979 ft /see hr 3600 sec 7 48 gal 8.337 lbs 3 Velocity = 34.979 ft /sec 11.13 ft/sec for each 24-inch pipe = 2 3 14 ft Reviewed by DNE l (- L---_ _ __

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r- ,I s t h g .~ -) .\\,, g =_ -f \\ .g .~. m f.%' 'Ti.*l pit.Ih$h [l* tW'.a .i 5' 1 l . 2,Y & g.- } Wes;*.*.'.r_%m*5% i ~ i-gl # N an===. I a ,g,,_ Figure 4 Crid No. 1-FW-1 24-inch, schedule 40 elbow (upstream of B pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch.

  • Minimum wall thickness measured by UT is 0 740-inch.
  • Readings were uniform. No erosion-corrosion damage detected.

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.f.* W* J, n:, 'o 'hg i - v 8 %[i txT = s w Figure 5 Grid Number 1-FW-2 24-inch, schedule 40 spool-piece and 45-degree elbow (upstream of B pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch.

  • Hinimum wall thickness measured by UT is 0.620-inch.

" Readings were uniform. No erosion-corrosion detected. e 8, e l l I J

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~~ M 9 T*7**."*MK f ' *W $J {/ { \\ -hiQ = .s 1 a ,(,g3 Figure 6 Grid Number 1-FW-3 30-inch, schedule 40 header (upstream of B pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.656-inch.

  • Minimum wall thickness =easured by UT is 0 760-inch.

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-Qw; s s ^* .w, N Figure 7 i Grid Number 1-FW-4 24-by 16-inch, schedule 80 reducing elbow (discharge side of B pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.740-inch.

  • Minimum wall thickness measured bl' UT is 0.830-inch.

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~. m is nL a =~ g ) pf\\\\ f -- ? .__t a 1 ' ' jYh-s=R Q ! 5YWWMfY h / I a,' - * $f. s , ; = -- h Q - -aln;n. 4 %! -- - - m.Q w, :,,, .A s. ~ ' ' a y ;'" = x 2:n h~1 M... F2- --~~,~-. ) .s W .,. ] 1 ( k g :. Jai.h 1- ..,.g ~% Figure 8 Orid Number 1-FW-5 24-inch, schedule 40 elbok and 24-by 16-inch, schedule 40 reducing elbow (upstream B pump). Minimum wall thickness in accordance with ANSI B16 9 is: 24-inch elbow - 0.602-inch and 24-by 16-inch reducing elbow - 0.4375-inch.

  • Minimum wall thickness measured by UT is 0.740-inch.

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1 5~,, - =.. 7W' 5 l 1 .IV t' .9 'e ~ g ' Q. ' U- -.. s ?. 9 ~ ^~ 1 Fictre 9 Grid 1 umber 1-FW-6 24-inch, schedule 40 elbow (upstream A pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch.

  • Minimum wall thickness measured by UT is 0.740-inch.

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lU 1 3 3gig 4 ff ',.f g. .m i ts. s -= 7 9 "? \\ jg E y %. ~ \\ ~ M ./ Y,, 4 Figure 10 ~~ Grid Number 1-FW-7 24-inch, schedule 40 header and 45-degree elbow (upstream A pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.602-inch.

  • Minimum wall thickness measured by UT is 0.660-inch.

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~ ~ ~- C a m .[ t., fQQ l l~ [~ y R .Q mm / ~' I ~ o ~ .,5,m / d.,g.yY[Nat. l.'g@! h.. I 3; j [ M.:" ik jj, J J, Y / Figure 11 Grid Number 1-FW-8 24-inch, schedule 40 elbow (upstream A pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch.

  • Minimum wall thickness measured by UT is 0 740-inch.

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.ge., "hb5 N (I W N- [ % ge' SIS 'qg$ag35Ch$ L: L- . 't ^- .;. %~M l f'a m. w. - [-m 3 ,4 6, Figure 13 Crid Number 1-FW-10 24-inch, schedule 40 elbow and 24-by 16-inch, schedule 40 reducing elbow (suction side A pump). Minimum wall thickness in accordance with ANSI B16 9 is: 24-inch elbow - 0.602-inch and 24-by 16-inch reducing elbow - 0.4375-inch.

  • Minimum wall thickness measured by UT is 0 740-inch.

p 89 F

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f ^ }l& hh- ^ '.4 ('9; .r 1 Figure 14 Grid No. 1-FW-11 20-inch, schedule 40 elbow (upstream A train, No. 2 feedwater heaters). Minimum wall thickness in accordance s with ANSI B16.9 is 0 520-inch.

  • Minimum wall thickness measured by UT is 0.560-inch.

ee O e 4 l l I L. J

4 i _ __.,,gy -q 3 l -;A w..- # 1 .h L ,- h..y.. s. .. w S \\' \\. i i, f ( :

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. \\L- *\\ Figure 15 Crid number 1-FW-12 20-inch, schedule 40 elbow (upstream C train No. 2 feedwater heater). Minimum wall thickness in accordance with ANSI B16.9 is 0.520-inch. l

  • Minimum wall thickness meas wed by UT is 0.580-inch.

89 I I 1

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  • Ylrh,Y.c(Y;;

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Figure 16 Unit 1 C-Train No. 2 Feedwater Heaters Metallurgical inspections were performed at numbered locations. Results are as follows: 1. No degradation of adhering magnetite film. Backing-ring protruded into fluid stream. No wear was observed on the backing-ring. I 2. N6 degradation of adhering magnetite film. 3 Superficial impingement from inlet stream. No I degradation observed. I l l } } I i l l

l l l l 4 I I .... t,.,-, 3,{, 1 jY i

Tn?

h i ! p i Figure 17 Grid No. 2-FW-1 24-inch, schedule 40 elbow (upstream of B pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch.

  • Minimum wall thickness ceasured by UT is 0.680-inch 8 Readings were uniform. No erosion-corrosion damage detected.

1 t

a 4 e fh TrL M k.~,- ~ ~ i 745'~2b$ [_l ^^ ~~ E ..m M UM p~ 9

-y w

. n h- ~ ~ ~ -- q!!ay f,at 5. ~wf.c.

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. ~,. ' i *- g, "Qs 4, ff k [' f e, s b ~ %[ ~ Ab r Figure 18 Grid No. 2-FW-2 24-inch, schedule 40 spool-piece and 45-degree elbow I (upstream of B pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.602-inch.

  • Minimum wall thickness measured by UT is 0.620-inch.
  • Readings were uniform. No erosion-corrosion detected.

8 00 I } ~ L_____-___--

) i l I ~ t ,-1-FW-3 Ja, mite.a ,s

u. <o w... s p-

[ l af- -. - p_ M y-is'- l ',?_. k:-: S &&& .G %f h W 2 e r m enemmial M m ' ^ '" - O Y ";a E & & & it }_ ___ ' ~ k@% y&n+ ~, . ~.- }.y. f i:.~; v y.t m %_.W'- x ~ ~ ~ ? a 4 I -mW3 g 4 Figur,e 19 Grid No. 2-FW-3 } 30-inch, schedule 40 header (upstream of B pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.656-inch.

  • Minimum wall thickness measured by UT is 0.760-inch.

.e e 6

. _ - = = . d f -- g \\ w :. k .~ A m.. [ p f e._,< ? Ce<mn... ' .y ' s,,g. l . _m" 'n .1 G.;rj. . Ai. y G i. o C h '~ 9 9 Q v-I .; v Figure 20 Grid No. 2-FW-4 24-inch, schedule 40 elbow and 24-by 16 i reducing elbow (upstream b pump). - nch, schedule 40 \\ in accordance with ANSI B16 9 is: Minimum wall thickness and 24-by 16-inch reducing elbow - 0.4375 in h24-inch elbow - 0 -c.

  • Minimum wall thickness measured by UT is 0 550-inch l

l e I 1

A 49 a M 'l + t ,i. h, f 54 ~ 4 r -d k ) tj

  1. 7 1

~ t. v g -s.,t, e., o. ~;,, u - -j' .y...,. J Figure 21 Grid No. 2-FW-0 24-by 16-inch, schedule 80 reducing elbow (discharge side of B pump). Minimum wall thickness in accordance with ANSI B16 9 is 0.740-inch. e Minimum wall thickness measured by UT is 0.680-inch. e

M-.c s i Milir" s' , /,' l f. ~*~ N }~ Q - .di$' ' ~~~ j ..J Figure 22 Grid tio. 2-FW-6 24-inch, schedule 40 elbow (upstream A pump). Minimum wall thickness in accordance with A!!SI B16.9 is 0.602. inch.

  • Minimum wall thickness measured by UT is 0.710-inch gp 4

l i l l l ~ ~ - C?Q4 _= -- -m l ~ .eY \\

r

-a. 'k ,s k ./ /V 2} ~

  1. I Q-FW-7 1

Figure 23 I Grid No. 2-FW-7 24-inch, schedule 40 header and 45-degree elbow (upstream A pump). Minimum wall thickness in accordance with ANSI B16.9 is 0.602-inch. )

  • Minimum wall thickness measured by UT is 0.610-inch.

3 4 m

i ? 4 , }' ',. '*/ -~ .g kf ~ i f I 1 l l l l Q2 r.- ~ I . s.v., A. {*\\ \\ 3 ..m a. r-l O PI 'J ~ li E ' t.: =.v m a~M> Figure 24 Grid No. 2-FW-8 24-inch, schedule 40 elbow (upstream A pump). Minimum wall thickness in acccedance with ANSI B16.9 is 0.602-inch. 8 Minimum wall thickness measured by UT is 0.700-inch. L l

l / Q k{ g.;ty fs 1:.0; i l' Ih' \\ Q. [ y, 'ahh kg w = s r = i +~ r.y l ( g \\ 1 s .. .c g b Figure 25 Grid No. 2-FW-9 24-by 16-inch, schedule 80 reducing (discharge A pump). elbow accordance with ANSI B16.9 is 0 740-inchMin!

  • Minimum wall thicknes s measured by UT is 0.720-inch.

8 _ Suspect minor cavitation damage in Crid I-14 (see photo above) ? e 0 l l I

! TI$""IfRmReMM9]iiE! j uNE Em i isie a ll g g g j i i prmmsi;&=- e-N EIM l. I ~w ' . sr Y p~ .~ C.e ~ .ac...E.?. .~ Figure 26 ) Grid No. 2-FW-10 24-inch, schedule 40 elbow and 24-by 16-inch, schedule 40 reducing elbow (suction side A pump). Minimum wall thickness in accordance with ANSI B16 9 is: 24-inch elbow - 0.602-inch and 24-by 16-inch reducing elbow - 0 3475-inch.

  • M.inimum wall thickness measured by UT is 0.670-inch.

.O I 1 j

n 1" W

  • 4.

~ / y; .. $7 ~^ [ fg d__J-M a l e 7 Ax+_c ~' -~ A.; m-- l ---M 3%

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' ic r,\\ f Id'l. l W ..... cr. p ] ie 'm - afr ,a. ri gJp;-1' ^4-O l f.& A 7 i _ = _. 9... i h _ ' = - - - ' .+ Figure 27 j l Ocid No. 2-FW-11 20-inch, schedule 40 elbow (upstream A train, No. 2 feedwater heaters). Minimum wall thickness in accordance with ANSI B16.9 is 0 520-inch.

  • Minimum wall thickness measured by UT is 0.600-inch.

es l l e e 9

~, j o. Anzw-QM .t i y eigen A m s <( j g 1 jl d j ii i h mwwn4 w; q mgmwic;f;e j O, .x ;:.. . y. tj il '~ I I g gERE a fE31sn Adw t g g.. y i en: jil E % :E M E S Figure 28 Grid No. 2-FW12 20-inch, schedule 40 elbow (upstream C train No. 2 feedwater heater). Minimum wall thickness in i accordance with ANSI B16.9 is 0.520-inch. t

  • Minimum wall thickness measured by UT is 0 580-inch.

1 j e e

~

S ........ ~, 870417T0076 uNrrto m rz covEx o c.s,. Memorandum TENNESSEE VALLEY AUTHORITY B25 '870408 0 6 7_.- To-H. L. Abercrombie, Site Director, C&PS 4, SEquoyan Nuclear Plant ruost D. W. Wilson, Project Engineer, Sequoyah Engineering Project, DSC-E, Sequoyah Nuclese Plant DATE APR 0 81987 stBJECT: SEQUOYAH NUCLEAR PLANT UNIT 2 - WALL THINNING ASSESSMENT PROGRAM FINAL REPCRT

References:

1. My memorandum to you dated January 27, 1987, "Sequoyah Nuclear Plant Units 1 and 2 - Preliminary Report on the Condensate-Feedwater Piping Inspection - Suspected Crosion-Corrosion Areas" (B25 870127 028) 1 2. C. R. Brimer's memorandum to L. H. Nobles dated March 6, 1987, "Sequoyah Nuclear Plant Unit 2 - Preliminary 8 valuation of the Turbine Building Heat Cycle Piping" (B29 870306 001--copy attached) J Attached is the final report on the unit 2 wall thinning inspection program. The.. inspection initially began with the condensate-feedwater system, but was expanded to include all heat cycle piping. The results identified localized damage on the feedwater piping and hign pressure vent lines. The major damage of the feedwater piping was attributed to a 4 situation caused by a 12-inch feedwater flow control valve (FCV) in a j 16-inch line that introduces 9-inch diameter restrictions. This caused the I fluid to accelerate to high velocity before discharging downstream and ] subsequently degrading the carbsn steel 16-inch schedule 80 elbows, the j 16-by 18-inch increasers, and the 18-inch diameter piping. The piping geometry downstream of valve 2-FCV-3-103 is slightly different than that of the other three FCVs. An 18-inch 450 elbow is immediately downstream of the 16-by 18-inch increaser rather than the 18-inch piping as identified on the other three feedwater lines. This elbow showed some visual evidence of minor wall thinning, and ultrasonic test data confirmed the damage as being minor. Major damage was observed in a 2 1/2-inch schedule 80 elbow on operating vent line "A." Vent lines "B" & "C" adjacent to the damaged l line did not show any significant thirining. i Minor damage was observed on a reducing elbow during the initial condensate- ] feedwater piping inspection; however, less than 3 percent thinning was l found, and it appeared to be cavitation and/or an anomaly (see reference 1). j I I l i I i X i .W \\ \\ i

l o.* 2 l H. L. Abercrombie j l APR 0 81987 ~ i t SEQUOYAH NUCLEAR PLANT UNIT 2 - WALL T!! INNING ASSESSMENT PROGRAM FINAL REPORT l As a result. I as recommending that the identified damaged 16-inch elbows and 16-by 18-inch reducers be replaced with a more erosion-corrosion resistant material, preferably 304 stainless steel. A carbon steel base metal repair should be performed on the localised areas showing minor wall thinning on the 18-inch 450 elbow and the 18-inch clameter piping. Also, I am recommending that the Materials Engineering Section maintain a surveillance instruction and a database to monitor those areas inspected for the remainder of the plant's life. l -um A&M [ N OT N' N1180" CRB:RDB:RLP:HC Attachments cc (Attachments): RIMS. SL 26 C-X o reference) ~~M. R. Harding, 06Fs-4, Sequoyah (Attn: L. M. McCormick) R. E. Daniels, DSC-H, Sequoyah (Attn: J. E. Pilgrim) L. M. Nobles, POS-2, Sequoyah *( Attn: G. S. Soles)(w/o reference) J. H. Sullivan, SB-2, Sequoyah Principally Prepared By: R. L. Phillips and T. R. Woods l r HC7083 01 i

a ~ o SEQUOTAH NUCLEAR PLANT (SQN) UNIT 2 t/ALL THINNING ASSESSMENT PROGRAM - FINAL REPORT Int roduction SCM recently initiated an inspection program to identity wall thinning in its bulk single and dual phase riow systems. A preliminary inspection was performed on selected rittings to determine if generic thinning was occurring on the condensate-reedwater and extraction steam piping. The condensate-reedwater inspection was performed in December 1986, and the extraction steam was inspected in October 1984 for unit 2 and May 1985 for unit 1. The results did not reveal any significant thinning; however, the Materials Engineering 3ection evaluated technical information from the Surry Nuclear Plant event and decided to perform a detailed investigation or all the heat cycle piping. The systems that were evaluated were as follows: Single Phase Dual Phase Condenaate Extraction Steam Feedwater Heater Drains & Vent Lines Turbine Drain & Vent Lines Each were evaluated based on riow velocity, operating pressure, operating temperature, and geometric configuration..The water chemistry and material compositions were fixed variables and were assumed as constants. From the evaluations, approximately 150 areas were identified as being the most susceptible. Of these 150 arcas, 70 were targeted for examinations. Scope The purp e/ r of the assessment program was to determine the high auspect ~ areas ar.- ; hen to inspect and monitor these areas for the entire plant life. r-s ry had seen major damage arter approximately 76,000 hours of i operativ1 whereas, SQN has experienced approximately 25,000 hours. The l long-tors monitoring ir.itiated should prevent the occurrence of a i catastrophic rupture. The assessment program would also make any { corrective action recommendations. The program should identify wall l thinning due to cavitation (high pressure dirrerential), pure erosion (high velocity), pure corrosion (low velocity), erosion-corrosion, and any anomalies that would violate the design minimum wall thickness. Results l Ultrasonic Testing ~ Approximately 70 areas (Tables 1, 2, and 3) were examined by ultrasonic testing in accordance with N-UT-26. The results were compared to the l manufacturer's minimum wall thicknesses and the Division of Nuclear I Engineering's design minimum wall thicknesses. Any deviations round below j the manufacturer's minimum were noted, and those areas found below or rapidly approaching the design minimum were targeted for replacement. { l

( l \\ ' l The results identified two areas on the condensate-feedwater system with damage and one area on the high pressure operating vent lines. Significan t 7 damage was found downstream of the 12-inch feedwater valves. This damage was found on the 16-inch elbows and the 16-by Id-inch increasers. The damage was measured to be 30 percent below the design minimum wall thickness in some locali:ed areas on the 16-inch cibows and within 12 percent of the minimum design value on one of the increasers. Each of the increasers showed varying degrees of wall thinning. Hinor damage was noted on the 18-inch 450 elbow downstream of the 16-by 18-inch increaser on the No. 4 feedwater line and the 18-inch piping downstream of the 16-by 18-inch increaser on the Nos. 1, 2, and 3 reeawater lines. Significant damage was also identified on the "A" high pressure operating vent line. Lines B and C adjacent to the damaged line showed some thinning, but nothing significant. Each line has been targeted for replacement. t Minor damage had been detected earlier during the condensate-feedwater piping inspection on a reducing elbow of the main feedwater pusp discharge. The da= age was less than 3 percent of the manufacturer's minimum (see reference 1). Visual Testing l Approximately 11 elbows on the condensate-feecuater system were visually inspected for wall thinning. The 10 elbows upstream and downstream of the No. 2 feecwater inester did not show signs of damage (see reference 1). e The elbows, piping, and fitting im=ediately downstream of feedwater regulating valves showec var,ying degrees of wall thinning. There was,a clear demarcation revealing exposed base metal and protective magnetite. These j conditions are very characteristic of erosion-corrosion damage (see reference 1). Chemical Analysis Seven elbows were analysed for beneficial trace elements to complement the visual and ultrasonic inspections. Six elbows were randomly selected for analysis. All nad beneficial alloys present, anc the ultrasonic data did not identify thinning. The elbow downstream of 2-FCV-3-103 (No. 4 reeowater line) was analyzed, and no beneficial alloying element was found. This elbow had experienced significant wall degradation. Discussion and Recommendations SQN wall thinning assessment program did not dentify any widespread wall h i thinning as did Surry. The thinning was confined to isolated areas and i attributed to the inherent design. The primary wall thinning mechanism that was identified was erosion-corrosion, poth single and dual phase. Figures 1 and 2 show the effects of velocity, pH, and residual beneficial elements. Figure 3 shows the effect of geometry. The operating parameters k 1 i ) I

1 \\. e e t 3-l and the inspection confirmed the previous assumption that SCN has maintained gooo water chemistry, the primary cause of wall thinning. The ) Materials Engineering Section reco= mends the following corrective actions. I 1. The Materials Engineering Section shall establish a data base to maintain all inspection information. 2. The Haterials Engineering Section shall write surveillance instructions to conitor the suspect areas. 3 The Mechanical Maintenance Section shall replace degraded fittings with a more erosion-corrosion resistant material, preferably 304 stainless steel. Also a carbon steel base metal repair should be performed on the localized areas showing minor wall thinning on the 18-inch 450 elbow anu the 18-inch diameter piping. Rt.P:DR 3/26/87 IIC7083 01 O e e ee

t Table 1 g SECUOYAN NUCLGR PLMT WALL THINNING FR06 RAM REFER DCE LIST 10 NUst!A CESCRIPi!CM S!!E SCH DESI6N DES!6N MATERIAL FHASE PRE!!. YEMP. "

  • CD-1 COND RECl2C TO CONC D SER C 8.000 40 50 101 ASTK A106 62.8 WATER CNSTM FCV 2-3!A 2-CD-2 COND REC!RC TO CCNCD!D C B.000 40 50 101 ASTM A106 GR.B WATER DNSTRM OF ORIFICE 2CD-3 COND B0OSTER PUMP O!!CHAREE 14.000 30 675 400 ASTM A106 GR.B WATER 2 CD-5 CCND 100ST PUMP RECIRC 4.000 40 675 400 ASTM A106 6R.B WATER UPSIEE M VLV 2-629

{ 2 CD-6 COND 300$i PUMP RECISC 4.000 40 50 400 ASTM A106 62.8 DNSTREAM VLV 2-629 2-CD-7 90 DE6 ELL UPSTREAM OF B.000 40 3:0 263 ASTM A106 ER.B WATER FCV-2-3:A 2 CD-8 17 HEAfD BYPAIS TO CON!D!ER B.000 40 350 263 ASTM A106 GR.B WATER l UPSTRGM FCV-2-35A 2-CD-9 17 HEAID BTPASS TO CCHO B.000 40 50 101 ASTM A106 62.8 WATER UPSTREAM 0FQRiFICEFLS$ 2-ES-1 EI STM TO I4 F0WIR HTR DNSTFM 1.250 60 75 321 ASIM kl06 SR.B SIGM FCV 5-70 BYPASS 2-ES-3 EI STM CR CNSTM FCV :-98 2.000 60 0 0 STAINLESS STEEL FLA!HINS 2 ES-6 EI STM CR CNSTRM FCY 5 95 1.500 to 40 460 ASTM A106 6R.B FLASHIN6 2 ES-8 HP REHIR OPM VD T ON E! STM 16.,000 30 40 460 ASTM A106 ER.B !AT. STEM LINE

  • 2 IS-9 LP REHIR OPN VENT CN EI STM 20.000 20, 300 422 ASTM A106 6R.B 5 T. STEM LINE 2-ES- !!-A EI SIM 2* BYPASS CN FDWIR HTR 2.000 20 300 422 ASTM A106 6R.B SAT. STEM 12 2-ES-11-0 El STM 2' BYPASS CN FIVIR HIR 6.000 40 300 422 ASTM A106 6R.B

? 12 2 ES* 12 El SIM INLET 70 149 FtWTR HTP 19.000 STD 75 321 ASTM A106 6R.B STEM 2 ES-13 EI STM TURBlWE N0ZILE FOR 11 16.000 30 450 460 ASTM A106 6R.B SIGM HGIERS 2 ES-1 33 E!!RACTION TURBlNE N0ZILE! 20.000 20 200 !!B ASTM A106 6R.B STEM 2 ES-16 11 EI1RACTION TO MSR 12.000 40 450 460 ASTM A106 6R.B [2ES-17-A, HP FIHGIER OPERAI!N5 VENT 2.500 80 1085 600 ASTM A106 ER.B STEM

g i 2-ES-17 9 HP REHEATER OPERAi!NG VENT 2.500 80 1085 600 ASTM A106 GR.B STEM (2ES-17-Cj HP REHGIER OPERAi!NG VENT
2. 00 80 108 600 ASTM A106 6R.B STEAM 2 ES-IB-A LP REHEATER OPERATINS VENT 2.500 40 450 460 ASin A106 6R.B STEAM J

2-E!- 18 8 LP F.GGTER OPDA!!N6 VDT 2.500 40 450 460 ASIM A106 GR.B STEM l 2-ES-IS-C LP REHEATER OPERAi!N6 VENT 2.500 40 450 460 ASTM A106 6R.B SIEM j 2 ES-19 14 EITRACTICM C03NSTPEM OF 18.000 STD 75 321 ASTM A106 6R.B SIGM j FCV-5-70 l OFW-l 90 ELL UP$iRM VLV FCV 2 224 24.000 40 675 400 ASTM At06 6R.B WATER l 2-FW ~ 2 45 ELL UPSTRM VLV FCV 2 224 24.000 40 675 400 ASTM A106 6R.B WATER 2-FW-3A TEE UPST D MFPT 30.000 40 675 400 ASTM A106 GR.B VATER 2-FW-lB TEE UPSTRM MFPT 24.000 40 675 400* ASTM A104 GR.B WATER 2-FW-44 90 PEDUCING ELL MFPT-B SUCi!03 24.000 40 675 400 ASTM A106 ER.B WATER 2-FW-48 to REDUCIN6 ELL 3FFT B SUCTION 16.000 40 675 400 ASTM A106 6R.B WATER i 2 FW-3 90 REQUCING ELL MFFT ! 24.000 50 1085 600 ASTM A106 6R.B WATER Dl! CHARGE 2-FW-13 90 FEDUC!N6 ELL PFPI B 16.000 80 1085 600 ASTM A106 GR.B WATER O!SCHAR6E l r t l

Table 2 Page No. 2 W SEOUQYAN NUCLEAR PLANT WALL THINNIN6 FRO 6RAn REFERENCE LIST 10 NUM8ER CESCRIPi!CN $1!E SCH CESIGN DESIGN MATERIAL PHASE PRESS. Ilnf. 2 FW-6 10 ELL UPSTRn YLV FCV 2-221 24.000 40 675 400 ASTR A106 6R.B WATER 2 FW-7 45 ELL UPSf75 Vtv FC'.' 2-221 24.000 40 675 400 ASin A106 6R.3 WATER 2 Fu-8 to ELL UPSTRn vtv FCV-2-221 24.000 40 675 400 ASTR A106 62.8 WATER j 2 FW-94 90 FEDUCIN6 ELL MPT 4 24.000 80 1085 600 ASin A106 6R.3 WA!!R DISCHAR6E .jc2FW-18 to FEDUCIN6 ELL M PT A 16.000 80 1085 600 A$fa A106 6R.3 WATER DISCHAR6E 2-N-10A 10 REDUCIN6 ELL MPI A SUCT!CN 24.000 40 675 400 A$fM A106 ER.3 WATER 2 FW-108 10 REDUCING ELL nFPT A SUCT!CM 16.000 40 675 400 ASTM A106 6R.3 WATER 2FW- !! 90 ELL CWSTRR VLv FCV 2 !"8 20.000 40 675 400 ASTM A106 6R.S WATER 2 FW-12 10 ELL DWSTRM VLV FCV-2-167 20.000 to 675 400 ASTM A106 6R.3 WATER 2FW-13 10 ELL DSTRM VLV FCV !-81, 24.000 80 1085 600 ASTM A106 GR.8 WATEa RFPT 9 j 2-FW-14 90 ELL CWSTM VLV FCV 3-67, 24.000 80 1085 600 ASIN A106 ER.8 WATER nFPT-A 2-FN-16 FM 3YPASS TO CCND UPSTRM HCV 1.000 80 1085 600 ASTM A106 ER.3 WATER l 3 70 17 FEECWATER LOCP 4 CCWNSTFEAM CF 16.000 80 1085 600 ASTM A106 GR.S WATER 4 2 FN-FCV-3 10) { 2 FW-18 FEELWATER !YPASS HEADER C?F CF 8.000 80 102: 600 ASTM A106 6R.8 WATER 32' LINE l' 240- 2 11 FCWIR HTR OR !YPASS IQ CCND 6.000 40, 50 2?8 ASTM A106 GR.3 WATER CNSTRM LCV 6-!!B 2-h0-3 0; FDWIR HTR DR BYPASS TO CCND 8.000 40 26 387 ASin A104 IR.B WATER DtSTRM LCV 6 10:3 i 2-HD-4 LF PEHIR 81 PASS TO CCIO DNSTRH 8.000 40 410 460 ASTM A!C6 GR.3 WATER LCV 6-728 1 2-ML-5 13 HTR OR TK PURP O!! CHARGE 8.000 40 256 387 ASin A106 GR.8 WATER 2-HD-7 12 FW HIR GR TO 13 HIR DRA!H 6.000 40 2!6 387 A$in A106 6R.8 WATER TANK L t-8 HP REHIR !YPASS TO CCR0 CNSTRM 1.500 80 1085 600 ASTM A106 GA.B STIAM LCV 6-333 2*HD-9 MSRH DRAIN TANK BYPASS TO 6.000 40 10 408 ASTM A106 6R.B WATER CC3 DENSER 2 HD-10 Il FW HIE LR SYPASS TO CC30 18.000 STD 2:6 387 ASTR A106 GR.8 WATER UPSTREAM CCHO 2 HO-13 L? RHIR OR TK FLASHING HtR TO 0.000 40 450 460 ASTM A106 GR.S WATER HIR 2A2 - 90 DES ELL 2-HO-14 LF RHIA CR IX FLA!HING HUR 8.C00 40 450 460 ASTM A106 GR.3 WATER DNSTRM OF 6 124 2 HO-15 MSR CRAIN SYPASS TO CCNDEN!ER 8.000 40

256, 408 ASTM A104 6R.3 WATER 2 ND-16 il FM H5R DR BYPASS TO CCU 6.000 40 50 298 ASin A106 6R 8 WATER t!PSIREAM LCV-6 !!I 2-HD-17 62 FW HIR CR TO 13 HIR DRAIN B.000 40 300

-40 ASTR A106 GR.B WATER TANK (8YPASil 2-HO-18 13 FW HIR CR BYPASS IQ COND 8.000 40 256 387 ASTM A106 ER.3 WATER UPSIRR LCV 6 10!$ ~ 2 TO-I SIR !!AL CNSTM PCV 47 !SI 4.000 40 1035 600 ASTM A106 GR.B STEAM 2 10* 2 CKCSSUh0ER P!PE CRAIN TO 1.100 40 1035 600 ASin A106 6R.8 WATER C3 0ENSER CNSTFM FCV 1-7 s i

Tobic 3 Fy e No. 3 SEQUOTAH NUCLEAR PLANT WALL THINNING FROGRAM KEFERENCE LIST ID r,*attX OI!C2!?f!C1 !!IE SCH CE!!!N DES!6N MAf! RIAL M IE l FAESS. T E >,F. 2.TO-3 CKC551lNCER CRAIN TO C 30EX5ER 2.000 40 1085 600 ASTM A106 62.3 VATER C35f3M FCV 7-4 l

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... a. w .0 L. M. ticoles. acains Fit.u. Nr.scer. P03 0,.,,mu yan '!uc lea.-.'..i:- C. P.. Briear, Ansistar.t Project Eng).neer, Operatice s Engineering Services, Frost DEC-E, Sequcyan Nuclear Plant DATE MAR; o 6193,7 ~

SUBJECT:

SEQUOYA% 1TKhAR 7hANT UNIT 2 - PRD.Ih!NdRY EVALUATION OF TNT TURBINE BUILDING HEAT CYCLE PIPING

Reference:

Hemorardu:n fren it. L. Abercrombie to D. W., Wilson dated January 27, 1987, "Scqu' ayah Nuclear Pla.nt Units 1 and 2 - Preli=inary Report dn the condsnsate-Feedwater Piping Inspection - Suspedced Erosien-Corrosion Areas" (B25 870127 C20.-co'sy attached) i i 4 Attached is the preliminary evaluation of the Turbine Building heat cycle piping. This evaluation identifies areas of significant vall thinning and giva. recommended corrective actican to minimize or precAude unanticipated throughnrall failures. ORIGINAL SIGNED BY j C. R. BRIMER C. R. Bricer .\\'{), M E RDS:TRWt' Atte h=en s cc (Attach =edt): f]ypa !:.1,, 26 C.K (ufo referenc y by l l This Oas p.=iracipally preps: ed tf T. R. Voeds and R. L. Phillips. ~ i I i , =. t E M-HC7065.02 f ) c w .t m,s m La _-...1 ---x.

1* SEQUOYAH NUCLEAR PLANT UNIT 2 - PRELIMINARY EVALUATION CF THE TURBINE BUILDING HEAT CYCLE PIPING N Introduction Ultrasonic Test (UT) inspections were performed on the Turbine Building heat cycle piping to determine if any areas were degraded ss a result of erosion-corrosion da= age. These inspections were performed in addition to the initial inspections on the feedwater piping outlined in the referenced memorandum. For this UT evaluation, 46 areas were selected. Discussion The UT results shewed evidence of significant wall thinning in two locations. The first area where significant wall thinning was detected was in a 2 1/2-inch diameter schedule 80 carbon steel high pressure reheater operating vent line elbow. The remaining wall thickness in the A line elbow was =easured to be as low as 0.140 inch. Notable wall thinning was also cetected in the B nnd C line elbows. The design minimum wall thickness for tiis piping is 0.101 inch. Based on these results, the minimum wall criteria for the piping has not been violated; however, this piping should be considered for replacement before returning to service. The second area where significant wall thinning was detected was on the No. 4 feedwater line at a 16-inch schedule 80 carbon steel elbow i=cediately downstream.of 2-FCV-3-103 Wall thickness values on the elbow were measured to be as low as 0.460 inch, which violates' the design minimum wall thickness value of 0.562 inch for this fitting. This degradation was confined to the extrados (outer portion) of the elbow and covered an area of approximately 28 by 28 inches square. A subsequent visual inspection of the inside diameter surface confir=ed wall thinning in the extrados portion of this elbow. Areas where the magnetite film had been re=ov ; were noted along with the presence of patches of he=atite (i.e., non-protective oxide). The general surface condition was smooth and uniform indicating an even wear pattern. An investigation has shown that 16-inch valves were not available and 12-inch schedule 80 valves were modified to fit the 16-inch schedule 80 piping at these locations. This resulted in a localised velocity of approximately 36 ft/sec across the valve, which discharges into the outer portion of the elbow thereby enhancing the erosion-corrosion mechanism. Also, the chemical analysis of =aterisi shavings taken from the fitting showed that there were no beneficial alloyina elements present. As a result of these findings, a UT scan was cerformed on the Nos. 1, 2, ..and 3 fecewater lines at the identical elbow locations. These UT results { also showed evidence of significant wall thinning on the extrados of these l elbows. The minimum wall readings detected on,the Nos.1, 2, and 3 l feedwater line elbows were 0.480, 0.440, and 0.400 inch respectively. Each of these values is below the design minimum wall value of 0.562 inch for this piping. s i l -.__________________o

e .c. Conclusion and Recommendation ~ The metallurgic 1 inspections identified two areas of significant wall thinning. These degraded conditions were detected b/ UT methods and confir ed by visual inspection. Based on the findings, the following corrective actions are acceptable for making necessary repairs. 1. Replace the carbon steel vent line elbows and feedwater elbows with fittings fabricated frcm ASti A182 F304 stainless steel caterial. The 2 1/2-inch vent line piping should be replaced with AST:t A312 type 304 stainless steel material. This material upgrade is considered as the optinu:s repair because the stainless steel material should resist erosion-corrosion damage. If material availability prevents this repair from being implemented on the 16-inch feedwater elbow, alternate solutions to accress this existing condition are given below. 2. Clad the ID surface of a new carben steel elbow with type 309 stainless steel filler metal. The clad should be deposited in the identical area where degradation has been detected on the exist 4ng elbcus. 3 Deposit a full thickness weld build-up (i.e., pad weld) on the outside dia=eter surface of the affected area on the existing elbows. This repair should be considered as a temporary fix until a core per ::anent fix can te implemented during the unit 2 cycle 3 refueling, outage. Other areas where wall loss was noted during this evaluaticn will be identified in the final comprehensive report and will be targeted for cenitoring by a surveillance program. l l Rt.P:TR*J:HC 3/6/87 HC7065.02 Of e e. e

FJFJ, WALL THINNING INSPECTION DATA PLANT: 88 UNIT: / INSP. DATE: 4 /W SYSTEM: /MIf ' M '7~~ MTL. CLASS./ REFERENCE THICENESS: IcIdje 40 /E2- /Zo LOCATIONS INSPECTED: l PURPOSE MtNeP!!FMett: Fde ME / FOR WALL THINNING 7 INSPECTION DETAILS: ,A//A METHOD: INSTRUMENTS: GRIDS: INSPECTION RESULTS: A//4 /: CORRECTIVE ACTIONS.: REPAIR / REPLACEMENT 7 MATERIALS CHANGES 7 FAILURE ANALYSIS 7 6 ei># 1 DOCUMENTATION: Ali,~e dC#Gw-d% 8F A l /1/ImEb / ~1 - / *1/1 / L 1 *Y P ? 01 /1 f59) 1

- ~ - - - '~ ~ ~ f ' ihlf ,1 ; C. t L29 83:0317 859 MAR 171983 C.R.Faheau 12110 CST 2-C _m ( Subject SEQUOYAH NUCLEAR PLANK UNIT 1 - MOISTURE SEPARATOR REHEATER DRAIN A /2-INCH LINE FA h l Attached for your information is a copy of the failure analysis report pertaining to the subject pipe. ( E. F. Harwell GJP:TRW:FSB Attachments cc (Attachments): NUC PR ARMS, 1520 CST 2-C This was prepared principally by Terry R. Woods. B2067B.FB ? .e .e e 9 _ _ _ _ _.-}}

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