ML17261A185

LER 80-003/01T-0:on 800414,during Steam Generator Inservice Insp,One Tube in a Steam Generator & 34 Tubes in B Generator Showed Pluggable Indications.Probably Caused by Concentration of Caustics in Crevices

ML17261A185
Person / Time
Site:	Ginna
Issue date:	04/28/1980
From:	Curtis A ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML17249A866	List: ML17249A865 ML17261A185
References
LER-80-003-01T, LER-80-3-1T, NUDOCS 8005020230
Download: ML17261A185 (4)

Text

NRC I RM 366 U. S. NUCLEAR REGULATORY COMMISSION

,I7.77) .

80-003/

LlCFNSEE EVE NT REPORT (CAR 1282)05020 g5Ct

{PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

CONTROL BLOCK:

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~O 7 8 9 N Y R LICENSEE CODE E G I

14 Q2 15 0 0 0 0 0 0

-LICENSE NUMBER 0 0 0 25 Q3 26 4 1 1 LICENSE TYPE 1 1 30 Q4~ 57 CAT 58 Qs CON'T

~01 soU~c~ ML Q 0 5 0 0 0 2 4 4 7 0 4 1 4 8 0QB0 75 4 2 8 8 0 80 QB 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 REPORT DATE 7 8 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES Qlo During normal steam generator (SG) tube inservice inspection, 1 tube in "A" SG and 34 tubes in "B" SG showed pluggable indications. (T.S. 6.9.2.a(3)). Eddy current test-ing showed 1 "A" SG tube and 3 "B" SG tube indications above tube sheet, and 31 "B"

~os SG tube indications in crevice area similar to those reported in LER's79-006 and

~os79-022. 2 "B" outlet tubes with crevice indications and 1 "B" outlet tube without

~O7 indication were pulled for analysis.

~os 80 7 8 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

~OS ~CB Q11 E Q12 ~BQ13 H T E X C H 18 Q4 ~FQ13 19

~Z 20 Q13 7 8 9 10 11 12 13 SEQUENTIAL OCCURRENCE REPORT REVISION Qz LF R(RO Rteosz ACTION FUTURE EVENT YEAR

~80 21 22 EFFECT

~23 SHUTDOWN

~00 24 REPORT NO.

3 26

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27

~01 28 ATTACHMENT CODE 29 NPRD.4

,TYPE

~T 30 PRIME COMP.

+

31 NO.

32 0

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS Q22 SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

~BQ13 ~ZQ72 ~ZQzo ~ZQ>> 0 0 0 0 Y Qzs ~NQz4 ~NQzs W 1 2 0 Qzs 33 34 35 36 37 40 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS Q27 Probably concentration of caustics in crevices leading to intergranular attack. Other 4 most likely having small defects over past several years and have recently exceeded plugging criteria. After above tube pulling, tubes were either welded or mechanicall 3 plugged. Crevice boil out procedure developed to be used in this outage. SG is 4 Westinghouse series 44 with Inconel tubes size 0.875 in. OD .050 in. walls.

80 7 8 9 FACILITY ~3P METHOD OF POWER OTHER STATUS QSD DISCOVERY DISCOVERY DESCRIPTION Q32 STATUS 34 7

s 8 9 D Qzs ~00 10 0

12 Qzs 13 NA 44

~B8 45 46 Eddy current test of tubes for ISI 80 ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY Q NA LOCATION OF RELEASE Q 6 ~Z Q33 ~ZQ34 NA 8 9 10 44 45 80 7

PERSONNEL EXPOSURES NUIJIBER TYPE DESCRIPTION Q39 7 ~00 0 Q37 ~ZQss NA 80 7 8 9 11 12 13 PERSONNEL INJURIES NUMBER DESCRIPTIONQ41

~OO O Qso NA 80 7 8 9 11 12 LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION Q43 Z Q42 NA 8 9 10 80 7

ISSUED PUBLICITY DESCRIPTION ~ NRC USE ONI.Y 68 69 80 o 7 8 9 10 NAME OF PREPARER A. E. Curtis, III PHQNE.716 546-2700 ext. 2542 a

I Attachment tc LER 80-II13/01T-0 Rochester Gas and Electric Corporation R. E. Ginna Nuclear Power Plant, Unit No. 1 Docket No. 50-244 During the normal steam generator tube inservice inspection program, one (1) tube in the "A" steam generator and thirty-four (34) tubes in "B" steam generator showed degradation requiring plugging. No other tubes displayed abnormal degradation upon evaluation of all the multifrequency eddy current data. The one degraded tube in the "A" steam generator and three tubes in the "B" steam generator showed indications exceeding the plugging criteria. The indications in these four tubes on the periphery of the steam generators were above the top of the tube sheet. The indications in the other thirty-one tubes in the "B" steam generator were all in the tube sheet crevice.

The four periphery tubes which had indications are most probably defects which have been in the steam generator for several years and have now developed into pluggable indications. These indications were small volume signals without a great amount of depth; each one was under 50%

through wall.

The thirty-one tubes with crevice indications were located in the same general area where thirteen other crevice indications had been found in previous inspections, March and December 1979. Thirteen of the indi-cations found in this inspection were identified by all the eddy current frequencies. Eighteen other indications were only identified by the 100 KHz absolute frequency. The postulated cause of these crevice indications is caustic intergranular attack (IGA) of the tubing material resulting in ultimate cracking. Two of these tubes with indications from the "B" steam generator inlet were removed by pulling, along with one without any indication in the outlet for metallurgical and chemical analysis.

The concentration of caustics in the tube sheet crevices is postulated to be the result of the changing molar ratio of previously concentrated Na and PO4 during the original phosphate chemistry used prior to November 1974. Since that time all volatile treatment water chemistry has been main-tained with subsequent addition of full flow deep bed condensate deminer-alizers in January 1978.

In order to provide corrective action in the crevice region of the tube sheet a crevice flushing and boil out procedure has been developed for implementation during this outage. In general, the multifrequency eddy current examination results of Ginna Station's steam generators show that the AVT chemistry with full flow condensate polishing is proving extremely effective in minimizing corrosion effects above the tube sheet in the genera-tors. Therefore, the plant will continue to operate with full flow condensate polishing to minimize the ingress of unwanted chemical species. An eddy current examination and evaluation will be performed in accordance with the ISI program at the next annual refueling outage.