ML20155G649

Steam Generator 2 Inservice Insp Results

ML20155G649
Person / Time
Site:	Yankee Rowe
Issue date:	06/30/1987
From:	May D, Mellor R YANKEE ATOMIC ELECTRIC CO.
To:
Shared Package
ML20155G640	List: ML20155G636 ML20155G649 ML20155G666
References
NUDOCS 8806200042
Download: ML20155G649 (6)

Text

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. e STEAM GENERATOR NO. 2 INSERVICE INSPECTION RESULTS JUNE 198*/

i Prepared by:___ fMk _

D. F. May

_ _ _t2~ __ _W_ j_Jf[_ _

Date Nuclear Engineer p o by _ 2 _ _ _ _ _ . _ _ , , __ %_3,lil),___ __

R. A. Mellor Date Technical Director l

8806200042 880607 PDR ADOCK 05000029 o DCD

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I Introduction An inservice inspection of Steam Generator No.2 was (

performed in accordance with the surveillance requirements of Technical Specification 3.4.10 during May and June of 1987. Pursuant to Technical Specification 6.9.6, this special report is submitted as required by Technical Specification 4.4.10.5.b.

The Yankee Plant has four vertical U-tube steam generators (S/G), each containing 1620 tubes. The tubes are 3/4 inch O.D., type 304 stainless steel with a .072 inch average wall thickness. At the completion of the 1987 inservice inspection and

, subsequent plugging effort, a total of 509 of the 6,480 steam generator tubes have been plugged translating to only 4.77% of the total number of tubes.

References

1. YAEC letter to USNRC dated June 22, 1987 (FYR 87-66)

2. LER 87-006, "Defective Tubes Missed During 1984 Steam Generator Eddy Current Examination", FYR 87-69 dated July 2, 1987

3. Zetec report, "Assessment of Data Interpretation Techniques", dated July 16, 1987

4. Memorandum from C. G. Garrow to D. A. Maidrand, '

"Evaluation of the Potential 10CFR Part 21 -

Zetec Steam Generator Evaluation", dated September 29, 1987

5. Zetec Report, "Special Data Evaluation Technique for the Eddy Current Examination of Yankee Rowe Steam Generator Tubing", dated May 1987

6. Supplemental Report: Reanalysis of 1984 eddy current data for steam generators No. 3 and No.

4, FYR 88-80 Results .

The tube inspection was performed in accordance with Technical Specification 4.4.10.4.a.8 from the hot leg side of steam generator No. 2. Of the 1571 operable tubes, 1506 were inspected. The remainder were either blocwed by template plugs or inaccessible due to the position of the eddy current (E/C) fixture.

Twenty two tubes were found to have exceeded the maximum allowable imperfection depth of 40% and were therefore plugged. Of the 22, 8 were found to have grown 10% or less since the last inspection and were

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. e therefore not included in the determination of the classification of the results. With 1506 tubes inspected as the first sample, the remaining 14 defective tubes translated into 0.93% percent of the inspected tubes resulting in a C-2 classification.

Since the first sample was comprised of 100% of the accessible tubes, that is, all tubes not blocked by the eddy current equipment or template plugs, a second sampling was not required. Table I suruma r i z es the number and extent of the tubes j inspected. Table II lists the location and percent  !

of wall-thickness penetration for each indication of l an imperfection. I 1

i Discussion

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l Results of the inspection indicated 22 defective tubes. A review of previous data from the 1984 (cold leg only) and 1981 inspections was performed to determine the extent of further wall penetration for these defects. Tubes that had degraded less than 10% of the wall thickness since the last inspection would not be considered defective for the purposes of this inspection as allowed by Technical Specifications. As a result of the review, 9 tubes were found that apparently should have been plugged in 1984. The failure to detect defective tubes during the 1984 inspection has been attributed to the improvements in eddy current inspection and evaluation techniques and also to the lack of a secondary review of the eddy current data.

Corrective actions rere provided in Reference 2.

Previous data for steam generators No. 1, No. 3 and No. 4 was also reviewed. Additional defective tubes were found in steam generators No. 3 and No. 4 which were subsequently plugged. Details of this issue can be found in a supplemental report (Reference 6).

An evaluation (Reference 4) conducted after the E/C testing concluded the deviations experienced during the 1984 inspection were not reportable under 10 CFR Part 21.

In 1984 and 1985 inspections of S/G No. 2 were also r performeo but the presence of magnetite on the ID of the tubes on the ho t leg side of the generator I

distorted the E/C signals. Prior to the 1987 f inspection it was decided to upgrade from the MIZ-12 to the MIZ-18 E/C data acquisition system.

Utilizing the advanced tech ology of the MI2-18 system, Zetec was able to develop a method (Reference 5) of eliminating the magnetite signal and thereby producing valid E/C date in the region of the generator containing magnetite deposits.

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TADLE I - STEAM GENERATOR NO. 2 INSPECTION DETAILS Cateuorv # of Tubes % of Total Extent Previously plugged 49 3.02 Not inspected Blocked by fixture 49 3.02 Not inspected or unreachable Blocked by template 16 1.00 Not inspected plug Ho; leg only 313 19.32 To U-bend Hot and cold leq 1193 73.64 To cold leg tube end j i

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l TABLE II - STEAM GENERATOR NO. 2 INSPECTION RESULTS (includes review of previous data)

Row Column  % Degradation Location of Degradation Plugged H 42 37 TE-HL+ JP.6 YES 47 TE-HL+ 13.2 ---

'33 TE-HL+ 13.7 ---

N 41 38 TTS-HL+ 2.4 YES I 41 51 TTS-HL+ 2.5 YES H 41 53 TTS-HL+ 1.7 YES G 39 37 TTS-CL+ 2.7 NO K 38 58 TTS-HL+ 2.7 YES H 35 54 TTS-CL+ 1.6 YES H 34 56 TTS-CL+ 1.2 YES G 32 24 TTS-CL+ 1.3 NO K 32 39 TTS-CL+ 1.2 YES J 31 47 TTS-CL+ 1.0 YES Y 27 <20 1-AVB+ 0.0 NO K 26 36 TTS-CL+ 1.4 NO K 25 53 TTS-CL+ 1.3 YES J 23 79 TTS-CL+ 1,0 YES  ;

H 27 24 TTS-CL+ .9 NO I J 27 57 TTS-CL+ 1.4 YES G 25 69 TTS-CL+ 1.7 YES 62 TTS-CL+ 2.5 ---

45 TTS-CL+ 4.9 ---

H 25 49 TTS-CL+ 2.7 YES l

<20 TTS-CL+ 0.8 ---

G 24 45 TTS-CL+ 2.3 YES G 23 24 TTS-CL+ 1.9 NO G 22 28 TTS-CL+ 2.0 NO G 31 32 TTS-CL+ 0.5 NO j Y 24 <20 4-AVB+ 0.0 NO

<20 1-AVB+ O.0 ---

Y 23 39 4-AVB+ O.0 YES 31 1-AVB+ 0.0 ---

Y 22 24 4-AVB+ 0.0 YES 42 1-AVD+ 0.0 ---

T 20 50 TTS-CL+ 0.1 YES H 15 38 TTS-CL+ 0.8 YES P 19 35 TTS-CL+ 0.8 NO Y 53 22 4-AVB+ 0.0 NO EE 27 <20 1-AVB+ O.0 YES 51 4-AVB+ 0.0 ---

l E 47 29 TTS-HL+ 1.7 NO l F 48 21 TTS-HL+ 1.8 NO  ;

F 49 67 TTS-HL+ 1.8 YES {

l 45 39 TTS-HL+ O.9 NO F 45 <20 TTS-HL+ 2.3 NO G 40 44 TTS-CL+ 1.4 YES I 40 28 TTS-HL+ 2.1 NO K 40 58 TTS-HL+ 2.2 YES

t TABLE II CONTINUED Row Column  % Degradation Location of Degradation Plugged N 40 48 TTS-HL+ 1.9 YES I 39 51 TTS-CL+ 1.4 YES 49 TTS-HL+ 2.2 ---

<20 TTS-HL+ 4.1 ---

I 38 39 TTS-HL+ 1.3 NO G 34 33 TTS-CL+ 1.0 NO Y 33 <20 4-AVB + 0.0 NO DD 31 <20 4-AVB + 0.0 NO S 32 37 TTS-HL+ 5.0 NO DD 30 <20 4-AVB + 0.0 NO K 24 38 TTS-CL+ 0.8 NO H 22 39 TTS-CL+ 1.0 NO I 22 28 TTS-CL+ 0.7 NO H 27 31 TTS-CL+ 1.5 NO

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G 24 28 TTS-CL+ 1.8 NO H 30 39 TTS-CL+ 1.0 NO F 22 39 TTS-CL+ 0.8 NO E 24 49 TTS-CL+ 0.7 YES E 41 <20 TTS-CL+ 1.6 NO l B 41 031 TTS-CL+ 0.3 NO l E 42 031 TTS-CL+ 1.2 NO l D 43 022 TTS-CL+ 3.1 NO D 44 038 TTS-CL+ 0.8 NO D 45 029 TTS-CL+ 2.7 NO E 51 025 TTS-CL+ 1.0 NO F 36 038 TTS-CL+ O.5 NO AVD - Antivibration Bar CL - Cold Leg HL - Hot Leg TE - Tube End TTS - Top of Tube Sheet i

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