ML20024D202

Provides Results of Jul 1983 once-through Steam Generator Insp.Preliminary Evaluation of Data Indicates Significant Degradation Appears to Be Occurring in Lane & Lane Periphery Region

ML20024D202
Person / Time
Site:	Arkansas Nuclear
Issue date:	07/29/1983
From:	John Marshall ARKANSAS POWER & LIGHT CO.
To:	Stolz J Office of Nuclear Reactor Regulation
References
1CAN078312, 1CAN78312, NUDOCS 8308030297
Download: ML20024D202 (10)

Text

, 4 ARKANSAS POWER & LIGHT COMPANY POST OFFICE box 551 UTTLE ROCK. ARKANSAS 72203 (501) 371-4000 July 29, 1983 1CAN078312 Director of Nuclear Reactor Regulation ATTN: Mr. J. F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 July 1983 ANO-1 A-0TSG Tube Inspection Gentlemen:

The following is provided to inform you of the results of the July 1983 ANO-1 A-Once Through Steam Generator (A-0TSG) inspection.

ANO-1 was taken off line on July 7,1983, following indication of an increase in primary to secondary leakage in the A-0TSG. The A-0TSG had been indicating a slight (approximately 0.007 gpm) primary to secondary leakage since plant startup from the November 1982 refueling outage. On the evening of July 7, 1983, the leak rate slowly increased to approximately 0.1 gpm. At this point, the decision was made by AP&L management to bring the unit down for repair of the leak. This decision was based on considerations regarding secondery system contamination. As the unit was being shutdown the leakage increase, as expected due to thermal stresses during cooldown, to a maximum primary to secondary leakage of approximately 0.2 gpm (as indicated through volumetric analysis). The maximum leak rate experienced during the cooldown was within the limits of Technical Specification 3.1.6. The I-131 dose equivalent measured in the secondary coolant on July 7, 1983 was 1.44 x 10-7 pCi/gm. This measurement was within the limits of Technical Specification 3.10.

The leaking tube (77-18) was found during bubble testing of the A-0TSG (To accomplish bubble testing the primary side water level is lowered to the top of the upper tube sheet; the shell side of the generator is then pressurized with nitrogen and the secondary side water level is slowly lowered. Bubbles 8308030297 830729 0 DR ADOCK 05000 l MEMBER MtOOLE SOUTH UTIUTIES SYSTEM

Mr. J. F. Stolz July 29, 1983 form in the leaking tube and are exhibited at the primary side tube _ sheet as the secondary water level drops past the leak location). Eddy-current testing confirmed the defect to be located in tube 77-18 at the upper tube sheet face. Since tube 77-18 had no previous indication of degradation., it was decided that further examination of the A-0TSG was warranted. Ultimately a total of 584 tubes were inspected.' The inspection included a full length eddy-current examination of all previously degraded tubes and an examination down to the 15th tube support plate of all unplugged tubes in the lane and lane periphery region as shown in figure 1. The region shown in figure 1 consisted of 533 unplugged tubes.

The eddy-current results from testing the previously degraded tubes are shown in Table 1. A tabulation of all degraded and defective tubes identified during the July inspection are shown in Tables 2 and 3 respectively. In addition to tubes identified in Table 3, eleven other tubes were plugged during the outage, eight were plugged as a precaution based on recommendations of the B&W personnel performing the generator inspection and three others were erroneously plugged.

A preliminary evaluation of the data from the latest inspection indicates, that the only significant degradation appears to be occurring in the lane and lane periphery region. This evaluation and the preliminary data from the inspection were discussed with the NRC in a telephone conversation between AP&L's Mr. Dan Howard et.al. and NRC's Mr. Guy Vissing et.al on July 15, 1983. As discussed with Mr. Guy Vissing of your staff, these latest tube inspection results will be presented at a future meeting between AP&L and the NRC in which AP&L will also present the results from the ANO-1 steam generator pulled tube examination.

ANO-1 was brought back on line on July 26. The unit is currently operating with no indications of primary to secondary leakage.

Very truly yours, ohn R. Marshall Manager, Licensing JRM:DEJ:sc Attachments .

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TABLE 1 ANO-1 A-0TSG INSPECTION RESULTS OF DEGRADED TUBES IDENTIFIED DURING NOVEMBER 1982 INSPECTION (20 to 39% THROUGH WALL) i Table 1 Tube . Indication Percent Through Percent Through Number (row-tube) Location Wall 11/82 Wall 7/83 1 10-31 UTSM 26 23 1

2 12-46 UTSM 25 34 3 21-55 UTSM 36 321 4 26-55 UTSM 24 NRI 5 29-49 15 TSP-UTSF 26 NRI 6 31-13 UTSM 34 34 7 39-13 UTSM 31 NRI 8 39-18 UTSM 24 NRI 9 48-15 UTSM 25 NRI 10 50-22 UTSM 39 NRI 11 51-111 1-2 TSP 36 NRI 12 52-9 UTSM 39 44 13 57-9 UTSM 38 57 14 57-29 UTSM 36 NRI 15 61-75 UTSM 38 NRI 16 61-117 UTSM 20 31 17 65-1 UTSM 38 NRI 18 65-11 UTSM 21 NRI 19 65-80 10-11 TSP 31 NRI 20 66-24 UTSM 31 31 21 68-2 UTSM 33 NRI 22 68-11 UTSM 37 41

. ~ _ _ , . . . - . _ _ .. . - -- _ _ _ . - _ . , _ _.

i Thble1 Tuba Indication Parcant Through Percent Through Numbtr (row-tubs) Location Wall 11/82 Wall 7/83 23 69-13 UTSM 37 23 24 71-11 UTSM 36 40

25 71-25 UTSM 26 NRI 26 71-34 UTSM 24 412

(

27 71-55 UTSM 23 34 28' 71-61 UTSM 22 282 29 72-5 UTSH 23 NRI 30 72-7 UTSM 24 NRI UTSM 39 NRI UTSM 20 NRI i

31 72-18 UTSM 37 NRI 32 72-106 UTSM 20 NRI 33 72-130 10 TSP 24 NRI

! 34 73-6 UTSM 23 NRI i 35 75-5 14 TSP 27 NRI u 36 75-14 UTSM 34 NRI

! UTSM 31 NRI 137 75-64 12-13 TSP 39 44 38 77-11 UTSM 36 352 39 79-123 12-13 TSP 21 NRI l 40 81-12 UTSM 33 40 41 81-14 10-11 TSP 26 NRI

. 42 81-19 UTSM 35 NRI i

43 81-54 UTSM 31 NRI i 44 81-63 13-14 TSP 20 NRI 45 82-59 UTSM 27 28 46 82-62 UTSM 32 29 f

l 4

, . - . . , . . - . , _ - , , . _ . . ,,,,...,,,,,,,.,,,,,r,.,_.._,.,_...,_.,~.-.__.....-.....m-,,__,-m.m._, -

,,,,_,_-m___._ _ _ _ . - . _ - - _ _ . _ _ .

Thble1 Tubs Indication Parcant Through Parcant Through Numbzr Dow-tube) Location Wall 11/82 Wall 7/83 47 83-11 UTSM 35 NRI 48 84-11 UTSM 36 NRI 49 84-12 LTSM 28 NRI 50 85-2 UTSH 35 NRI 51 86-12 UTSM 34 32 52 87-1 UTSM 29 31 t

53 87-11 UTSM 34 NRI 54 88-4 9-10 TSP 38 NRI 55 90-9 UTSM 27 29 56 96-120 UTSM 21 40 57 100-62 5 TSP 24 NRI 58 102-81 8-9 TSP 35 NRI 59 103-120 UTSM 35 43 60 104-2 UTSM 21 23 61 105-121 UTSM 25 40 62 107-13 UTSM 28 32 63 117-100 UTSM 30 38 64 119-13 UTSM 36 62 65 119-92 UTSM 27 35 66 126-97 UTSM 32 26 67 127-49 9-10 TSP 39 NRI UTSM - Upper Tube Sheet Mid-Span UTSF - Upper Tube Sheet Face i TSP - Tube Support Plate LTSM - Lower Tube Sheet Mid-Span NRI - No Recordable Indication 1During the 7/83 inspection only one indication was observed in the UTSM.

20uring the 7/83 inspection the indication was observed at the UTSF.

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. . - , - - - , . _ . , , _ . . , - . _ . . . , - . , . _ , . , - , _ _ , , , , _ _ _ . - . . _ . . , , c .. - - - _ . ,

TABLE 2 ANO-1 DEGRADED TUBES AS OF JULY 1983 INSPECTION (20 to 39% THROUGH WALL)

' Table 2 Tube Indication Percent Through Number (row-tube) Location Wall 7/83 1 10-31 UTSM 23 2 12-46 UTSM 34 3 21-55 UTSM 32 4 31-13 UTSM 34 5 61-117 UTSM 31 6 64-4 UTSM 39 7 66-24 UTSM 31 8 69-9 UTSH 21 9 69-13 UTSM 23 10 70-9 UTSM 38 11 71-55 UTSM 34 12 71-61 UTSF 28 13 72-3 UTSM 27 4

UTSM 35 14 72-14 UTSM 37 15 77-11 UTSF 35 16 79-5 UTSM 38 17 81-5 UTSM 29 18 81-6 UTSM 38 19 82-7 UTSM 26 20 82-14 UTSM 35 UTSM 29 t

- - , . . , . , _ , , . ,.-..,--,-g+-c. v.,-+- y~ ,,-,--,g., - - .w , ---c,- , -- ,- . , .,

Tablo 2 Tuba Indication Percent Through Numbtr (row-tube) location Wall 7/83-21 82-59 UTSM 28 22 82-62 UTSM 29 23- 83-5 UTSM 22 24 86-12 UTSM 32 2S 87-1 UTSM 31 26 90-9 UTSM 29 4

27 104-2 'UTSM 23 28 107-13 UTSM 32 29 117-100 UTSM 38 30 119-92 UTSM 35 31 126-97 UTSM 26

}- UTSM - Upper Tube Sheet Mid-Span UTSF - Upper Tube Sheet Face 4

TABLE 3 ANO-1 A-0TSG DEFECTIVE TUBES IDENTIFIED DURING JULY 1983 INSPECTION (240% THROUGH WALL)

Table 3 Tube Indication Percent Through

' Number (row-tube) Location Wall 7/83 i

1 52-9 UTSM 44 2- 57-9 UTSM 67 3- 68-10 UTSM 43 4 68 UTSM 41 5 71-11 UTSM 40 6 71-34 UTSF 41 7 75-12 UTSM 64 8 75-13 UTSM 64 UTSM 43 UTSM 37 9 75-19 UTSF 60 UTSM 68 10 75-31 UTSF 72 11 75-37 UTSF 95 12 75-53 UTSF 88 13 75-64' 12-13 TSP 44

{ 14 77-18 UTSM 70 4

UTSF 100 UTSM 37 15 77-20 UTSM 27 1

UTSM 72 1

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l Tcble 3 . Tuba Indication Parcant Through Number (row-tube) Location Wall 7/83 16 77-23 UTSM 68 UTSM 76 UTSF 85 17 77-26 UTSF- >50 4

18 77-27 UTSF >50 4

19 77 UTSF 74 20 77-51 UTSF' 72 21 77-54 UTSF 85 22 50 UTSM 85 23 80-1 UTSM 76 24 80-16 UTSM 44

25 81-11 UTSM 48 26 81-12 UTSM 40 27 82-12 UTSM 50 28 82-16 UTSM 57

, 29 .96-120 UTSM 40 30 103-120 UTSM 43 31 105-121 UTSM 40 32 119-13 UTSM 62

- UTSM . Upper Tube Sheet Mid-Span UTSF - Upper Tube Sheet Face TSP - Tube Support Plate d

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