ML060600189: Difference between revisions

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{{Adams
#REDIRECT [[NRC 2006-0027, Fall 2005 Unit 1 (U1R29) Steam Generator Tube Inspection Report]]
| number = ML060600189
| issue date = 02/21/2006
| title = Fall 2005 Unit 1 (U1R29) Steam Generator Tube Inspection Report
| author name = Koehl D L
| author affiliation = Nuclear Management Co, LLC
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000266
| license number = DPR-024
| contact person =
| case reference number = NRC 2006-0027
| document type = Inspection Report, Letter
| page count = 8
}}
 
=Text=
{{#Wiki_filter:t i- Committed to Nuclear Excellenc Point Beach Nuclear Plant Operated by Nuclear Management Company, LLC February 21, 2006 NRC 2006-0027 10 CFR 50.36 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington DC 20555 Point Beach Nuclear Plant Unit 1 Docket No. 50-266 License No. DPR-24 Fall 2005 Unit 1 (U1 R29) Stream Generator Tube Inspection Report In accordance with the requirements of Point Beach Nuclear Plant Technical Specification 5.6.8, "Steam Generator Tube Inspection Report," Nuclear Management Company, LLC (NMC), is submitting the results of the fall 2005 Unit 1 (U1 R29) steam generator tube inservice inspections.
The enclosed report includes the following:
: 1. Number and extent of tubes inspected.
: 2. Location and percent of all thickness penetration for each indication.
: 3. Identification of tubes plugged or repaired.This letter contains no new commitments and no revisions to existing commitments.
Dennis L. Koehl Site Vice-President, Point Beach Nuclear Plant Nuclear Management Company, LLC Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW 6590 Nuclear Road
* Two Rivers, Wisconsin 54241 Telephone:
920.755.2321 AcD(47 ENCLOSURE FALL 2005 UNIT 1 (U1R29) STEAM GENERATOR TUBE INSPECTION REPORT The Point Beach Nuclear Plant (PBNP) steam generator tube inspection program for Ul R29 was conducted in accordance with the requirements of PBNP Technical Specifications 5.5.8 and 5.6.8, NEI 97-06, "Steam Generator Program Guidelines," and EPRI 1003138, "PWR Steam Generator Examination Guidelines." The 29th refueling outage was completed on November 24, 2005. Past inspections of these steam generators have resulted in classification of Category C-1; therefore, this inspection was not required by PBNP Technical Specifications, NEI, or EPRI guidelines.
However, because of secondary side steam generator fouling, NMC performed an additional inspection of the Unit 1 'A' steam generator.
The PBNP Unit I steam generators are Westinghouse Model 44F with thermally treated, 7/8-inch outer diameter, 0.050 inch wall, Inconel 600 tubing manufactured by Westinghouse.
The tubes are on a 1.234" square pitch and were hydraulically expanded the full depth of the tubesheet.
The row 1 U-bends have a 2.19" radius, and the first 8 rows were stress relieved after bending. The tubes are supported by a stainless steel flow distribution baffle with round holes, six stainless steel tube support plates with quatrefoil holes and two sets of chrome-plated Inconel anti-vibration bar assemblies.
The PBNP Unit 1 steam generators were replaced late in 1983, during refueling outage 11. The replacement steam generators have accumulated approximately 17.7 effective full power years of operation since then.The U1 R29 steam generator inspection wvas limited to the 'A' steam generator and consisted of the following.
* Bobbin coil inspection of 50% (1607 tubes) of the active tubes over the full length of the tube. This included all tubes with previous anti-vibration bar wear and signature tubes. Signature tubes have potential elevated susceptibility to tube support plate Outside Diameter Stress Corrosion Cracking based on evaluation of past inspection data. The 'A' steam generator has 45 signature tubes.* Rotating pancake coil inspection of 20% (19 tubes) of the row 1 U-bends.* Rotating pancake coil inspection of 20% (644 tubes) of the tubesheel:
full length hot leg tubes to 3" above the tubesheet.
* Rotating pancake coil inspection of 146 special interest tests, including all freespan dings/dents over 5 volts and dings/dents over 2 volts at supports.As a result of this inspection, no steam generator tube degradation that required plugging was detected, and no tubes were plugged. The plugging limit at P13NP is 40% through-wall as specified in PBNP Technical Specification 5.5.8.a.6.
Tubes are Page 1 of 7 I also plugged upon any indication of circumferential or axial cracking.
Minor tube wear at the anti-vibration bars, at the hot leg top of tubesheet and at the cold leg supports continues to be monitored.
Fifty-two wear indications in 31 tubes were found in the 'A' SG anti-vibration bar area.None of these indications were required to be repaired, and all tubes remained in service. Table 1 shows all anti-vibration bar wear indications along with an historical comparison.
Based on the growth rate of the wear indications, no indications are expected to exceed the plugging criterion during the next two cycles.Table I -Anti-Vibration Bar Wear History, % Through-Wall, SG A Row Column Location 2005 2004 2001 1998 1995 22 8 AV3 3% ----32 14 AV3 7% 5% 3% 9% 4%33 18 AV3 18% 25% 21% --33 18 AV4 11% 16% 13% -35 18 AV2 11% 10% 6% INR 9%38 22 AV3 10% 12% 6% 10% 8%40 25 AV2 9% 6% 5% 9% 6%40 27 AV3 8% 5% 4% 6% 5%34 33 AV1 14% 10% 10% 5% 11%34 33 AV2 11% 7% 7% 7% 10%33 37 AV4 14% 9% 13% 7% 8%45 41 AV1 10% 6% 6% 7% 6%45 41 AV4 8% 7% 6% 7% 6%40 42 AV1 14% 12% 13% -23%45 42 AVI 14% ----38 43 AV1 24% 23% 19% 12% 11%38 43 AV2-1  17% 16% ---38 43 AV2+1  22% 23% 19% 12% 8%45 43 AV1 18% 13% 12% 15% 11%45 43 AV4 9% 8% 8% --40 44 AV3 11% 13% 10% 7% 5%40 47 AV3 15% 10% 13% 10% 12%33 48 AV3 9% 13% 9% --45 49 AV1 15% 19% 14% 13% 18%45 52 AV4 5% ---19 54 AV1 8% ----19 54 AV2 17% 12% 14% 13% 7%19 54 AV4 17% 12% 16% 12% 13%38 54 AV3 26% 25% 18% 14% 15%38 54 AV4 9% ---35 56 AVI 18% 14% 15% 5% 6%35 56 AV2 27% 27% 27% 9% 13%Page 2 of 7 Row Column Location 2005 2004 2001 1998 1995 19 61 AVI 13% 12% 18% 10% 12%19 61 AV2 16% 15% 23% 13% 14%19 61 AV4 5% 6% 8% --31 63 AV2 18% 20% 14% 9% 12%31 63 AV3 11% 10% 5% 5% 2%34 65 AV3 5% 9% 6% 1% -34 65 AV4 11% 15% 12% 6% 7%33 66 AV1 14% 20% 14% 9% 8%33 66 AV2 10% 13% 11% 9% 4%33 66 AV3 4% 5% 5% 4% 4%39 68 AV4 9% 9% 8% 9% 6%34 69 AV1 8% 3% 7% 1%34 69 AV2 16% 11% 14% 6% 9%27 71 AV2 10% 6% 11% 5% 4%27 71 AV3 15% 10% 12% 3% 2%27 71 AV4 7% 5% 6% -32 71 AV2 15% 11% 9% 10% 6%32 71 AV3 11% ----33 71 AV2 16% 13% 17% 5% 6%33 71 AV3 14% 6% 10% --Nineteen wear indications in 16 tubes were found in the 'A' SG peripheral hot leg tubes at the top of tubesheet.
Table 2 lists the percent through-wall of these indications.
All of these indications were reported in 2004, except a 1 % indication in row 33/column 78 and a 5% in row 41/column
: 28. Both of these minor indications were present in 2004 data but not reported by eddy current. These indications first appear in the UI R28 inspection data, and this wear was concluded to be the result of damage from maintenance equipment during Ul R26. Secondary side visual inspection during Ul R28 and the current inspection confirmed that no objects that could cause continued wear are present. Comparison of the 2004 and 2005 data supports this original conclusion.
The depth of these indications is significantly below the plugging criterion, and since the source of the wear is no longer present, no growth is anticipated, and all tubes remained in service.Page 3 of 7 Table 2 -Mechanical Wear History, % Through-Wall, SG A Row Column Location 2005 004 37 20 TSH +0.61" 4% 4%37 20 TSH +0.70" 1% 1%41 28 TSH +0.54" 5% -42 30 TSH +0.57" 5% 5%43 33 TSH +0.60" 3% 5%44 36 TSH +0.66" 4% 6%45 41 TSH +0.64" 3% 4%45 42 TSH +0.66" 1% 3%45 43 TSH +0.63" 2% 1%45 44 TSH +0.64" 3% 4%45 45 TSH +0.59" 4% 100%45 46 TSH +0.57" 2% 7%45 47 TSH +0.56" 2% 5%43 60 TSH +0.53" 7% 7%42 63 TSH +1.55" 1% 1%42 63 TSH +2.67" 1% 1%42 63 TSH +0.57" 11% 11%33 78 TSH +0.75" 1% -31 80 TSH +0.73" 4% 3%Four wear indications in 4 tubes were found in the 'A' SG at cold leg supports.
Three of these were reported in 2004, but had never been reported previous to 2004. When compared to 1995 inspection data, these indications showed no significant change.Table 3 lists the percent through-wall of these indications.
The depth of these indications is significantly below the plugging criterion, and all tubes remained in service.Table 3 -Cold Leg Support Wear, % Through-Wall, SG A Row Column Location 2005 2004 39 24 03C +0.38" 11% 12%41 65 02C +0.41" 16% 18%39 67 02C +0.38" 7% -21 85 02C +0.38" 12% 10%During this inspection of the 'A' steam generator, 3 dents were identified at :2.0 to 4.99 volts and 131 dings identified at 2.0 to 4.99 volts. Two of the dents were at supports, and 54 of the dings were located at supports or anti-vibration bars. An additional 53 dings were identified at 5 volts or greater. These indications were further investigated with rotating pancake coil, and the results were "no defect found." Page 4 of 7 The 'A' steam generator has one manufacturing anomaly. The tube at row 38/column 69 is not expanded the full length of the tubesheet.
This tube is routinely inspected by rotating pancake coil from the tube end to the top of tubesheel:
and during Ul R29, as in the past, no degradation was found. The tube remains in service.One possible loose part indication was reported by eddy current in SG 'A' at 0.36 inch above the hot leg top of tubesheet in row 8/column 25. No degradation was observed in conjunction with the indication.
However, all tubes adjacent to this indication were also tested with rotating pancake coil. Secondary side visual inspection verified that no loose part was present, and this indication was subsequently dispositioned, and the tube remains in service.A small foreign object was found and retrieved during the secondary side visual inspection near cold leg row 1 &2/column
: 78. The object was a small steel pin approximately 1-1/4" long by approximately 1/4" diameter.
Subsequently, 18 tubes in the vicinity of this location were inspected with rotating pancake coil. No degradation was observed in conjunction with the loose part in any of the tubes. The site investigated possible sources of the part and concluded that the object was not transported to the steam generator, but may have been from steam generator maintenance equipment.
The secondary side of the 'A' steam generator was cleaned and inspected.
Sludge lance equipment fit up properly, validating that the wrapper plate has not shifted.Therefore, wrapper plate inspection was not performed as discussed in our response to NRC Generic Letter 97-06. Sludge lancing removed 31 pounds of sludge from the top of the tubesheet.
The post sludge lancing visual inspection of the tubesheet confirmed that some hard adhering scale was not being washed off the tubesheet, acnd future chemical cleaning of the secondary side is planned. Inspection of the upper support plate revealed no degradation, nor was support plate degradation anticipated given that the plates are stainless steel. However, the inspection did confirm the presence of heavy scale on the outside of the tubes. The 'A' steam generator steam drum was also inspected and no significant degradation of the swirl vanes, moisture separators or feed ring J nozzles were found. Note that samples of these areas are visual inspected, and it is not practical to inspect 100% of all these areas. Minor weld burn through from construction was noted in two closely spaced J nozzles. The condition was evaluated and determined not to affect nozzle function.
No flow induced corrosion was found.The 'B' steam generator was not cleaned or inspected during the Ul R29 outage.Since the Unit 1 steam generators were replaced, tube wear has been minimal. There are presently a total of 10 tubes plugged in the Unit 1 steam generators
-four tubes in the 'A' steam generator and six tubes in the 'B' steam generator.
No tubes have been plugged for stress corrosion cracking and only four of these ten tubes were plugged as a result of service-induced wear -one tube in the 'A' steam generator and three in the'B' steam generator.
There are three tubes in the 'A' steam generator and cne tube in the 'B' steam generator that were plugged prior to placing the steam generators in Page 5 of 7 service, plus an additional two tubes in 'B3' steam generator were plugged because of damage during steam generator wrapper modification.
Tubes Plugged in Steann Generator A Row Column Date Plugged 1 5 During Manufacture (Welded in plugs)3 90 During Manufacture (Welded in plugs)20 87 During Manufacture (Welded in plugs)21 63 April 1991(690TT plugs)Tubes Plugged in Steam Generator B Row Column Date Plugged 1 1 April 1988/ Replaced with 690TT plugs in April 2001 2 1 April 1988 / Replaced with 690TT plugs in April 2001 30 60 April 1991 (6901T plugs)32 38 April 2001 (690TT plugs)35 51 April 1995 (690TT plugs)43 40 March 1984 / Replaced with 690TT plugs in April 2001 A steam generator tubesheet map is depicted on the next page to aid in the understanding of tube locations.
In summary, based on the inspection results, no tubes needed to be repaired.
The tube integrity and leakage criterion specified in NEI 97-06 are expected to be satisfied for the next cycle of operation.
In accordance with Point Beach Technical Specifications and EPRI Steam Generator Examination Guidelines, the next scheduled inspection of Unit 1 steam generators is planned for refueling outage 30 during the spring of 2007.Abbreviations AVx Various Anti-Vibration bar locations, numbered from hot leg to cold leg.If Anti-Vibration location is superscripted, there are multiple indications at the location.TSH Top of Tubesheet Hot Leg 02C 2nd support plate cold leg side 03C 3rd support plate cold leg side Indication Not Reportable Condition where a previously reported indication is detectable INR but does not meet the current reporting level.Page 6 of 7 Lo, mfl cost~g INLET NOZZLE NOZZLE SIDE MANWAY SIDE}}

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