ML19305B831

LER 80-002/01T-0:on 800227,primary-to-secondary Leak Was Identified in Steam Generator a Resulting in Shutdown of Unit.Caused by Leaking Tube at Position R18C37.Six Defective Tubes Found in Steam Generator a

ML19305B831
Person / Time
Site:	Point Beach
Issue date:	03/12/1980
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19305B830	List: ML19305B829 ML19305B831
References
LER-80-002-01T, LER-80-2-1T, NUDOCS 8003200441
Download: ML19305B831 (3)

Text

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NRC FOAM 366 U. S. NUCLEAR REGULATORY COMMISSION

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LICENSEE EVENT REPORT CONTROtstOCx:l 1

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' 8 61 NUMBE R 69 TS EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 10121 l Durina normal operation, indication of an increasing crimary-to l l0131l secondary leak in the "A" SG was noted on 02-27-80. The decision was l Io 141 l made to shut the unit down at 2340 hours0.0271 days <br />0.65 hours <br />0.00387 weeks <br />8.9037e-4 months <br /> on 02-27-86 and the unit was l IO ls i i off line at 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br /> on 02-28-80. Chemistry results of a sample l loisiitaken at 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> on 02-28-80 quantified a primary-to-secondary l l 017 l l leak rate of 1,420 gallons per day. This event is reportable per i 30,s1l T.S. 15.6.9.2.A.3 and is similar to previous LER's. l i 7 8 9 80 C DE CODE SUSC E COMPONENT CODE SU8 CODE S E g l C lB l@ y@ W @ l H l Tl E l Xl C l Hl@ lF l@ g @

7 8 9 10 11 12 13 18 19 20 SEQUENTIAL OCCURRENCE REPORT REVISION L EVENT VEAR R EPOR T NO. CODE TYPE N O.

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36 3' 40 el 43 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l i l 0 l l A primary-to-secondary leak test performed on 03-01-80 revealed a I t i l i l l leaking tube in the " A" SG at position R18C37. Eddy current +-p e i mr I i 2 l began in both SG's on 03-03-80 and was completed on 03-09-80. One I m l degraded (41% detect) tube was found in the "B" SG and six defective l 1 4 l (>50%) tubes and 18 tubes with pluggable (40% to 49%) defects were found 7 8 9 in the " A" steam generator. 80 ST S  % POWE R OTHER STATUS Ols V DISCOVERY DESCRIPTION i 5 l_E_j@ l 0 l9 l 9 l@l N/A l lA l@l Operator observation l ACTivtTY CO TENT

r. ELE ASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE l1lsl

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NAME OF PREPARER PHONE:

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l ATTACHMENT TO LICENSEE EVENT REPORT NO. 80-002/OlT-0 Wisconsin Electric Power Company Point Beach Nuclear Plant Unit 2 Docket No. 50-301 Unit 2 was taken off line at 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br /> on February 28, 1980, following confirmation of primary-to-secondary leakage in the "A" steam generator. The leak had begun as a slight indication about noon the previous day, and gradually increased to 70 gpd (estimated) by 2200, February 28. The decision was made to shut

, down at 2340 hours0.0271 days <br />0.65 hours <br />0.00387 weeks <br />8.9037e-4 months <br /> upon a further large increase in the air ejector radiation monitor reading. A static head leak check identified the leaking tube at position R18C37 and a subsequent eddy current inspection placed the defect at eight to ten inches above the tube end; i.e., thirteen to fifteen inches deep in the crevice of the tubesheet. The previously scheduled refueling outage steam generator eddy current inspection was performed during the outage. The extent of the inspection was expanded during the outage as six tubes with greater than 50% through-wall indications, in addition to the leaking tube, were discovered in the "A" steam generator. Eighteen tubes with indications between 40 and 49% were also found. The "A" steam generator hot leg program was first expanded by a 2S sample then to 100% as required by the Technical Specifications.

The 25 defective or degraded tubes in the "A" steam generator were explosively plugged on March 10, 1980. The leaking tube was mechanically plugged on the inlet side for future consideration of tube removal.

Eight tubes which exhibited 39% defect indications were also explosively plugged as a conservative measure. Two tubes, R22C62 and R9C54, also with 39% defects, were plugged on the cold leg only. These tubes may also be removed from the hot leg side during the April refueling outage.

An 800 psi hydrostatic test of the "B" steam generator revealed no leaking tubes or plugs. Approximately 700 tubes in each of the hot and cold legs of the "B" steam generator were examined and one cold leg tube was found to have a 41% defect indication. The one 41% degraded tube in the "B" steam generator was explosively plugged on March 9, 1980.

Unit 2 is expected to return to service on March 13, 1980.

The average radioactive release rate via the Unit 2 air ejector during this event has been calculated to be 0.051% of the allowable annual release rate of 0.2 Curies per second.

Additional information concerning this event will be provided in a supplemental report.

This event is reportable per Technical Specification 15.6.9.2.A.3.

EDDY CURRENT RESULTS FOR PLUGGED TUBES STEAM GENERATOR "A" INLET Tube  %' Defect Location R21C58 42 Top of tubesheet*

R10C59 39 Top of tubesheet R20C59 41 Top of tubesheet R21C59 39 Top of tubesheet R20C61 42 Top of tubesheet R20C63 51 Top of tubesheet R21C63 56 Top of tubesheet R10C64 42 Top of tubeuheet R21C64 46 Top of tubesheet R19C65 51 Top of tubesheet R18C68 39 Top of tubesheet R12C73 43 Top of tubesheet R34C73 43 First support plate RllC74 39 Top of tubesheet R07C21 39 Top of tubesheet R13C19 40 Top of tubesheet R12C31 41 Top of tubesheet R13C34 43 Top of tubesheet R14C34 57 Top of tubesheet R14 C35 42 Top of tubesheet R15C35 44 Top of tubesheet R13C36 42 Top of tubesheet R14C36 39 Top of tubesheet R10C39 45 Top of tubesheet R13C41 56 Top of tubesheet R18C37 100 9" above tube end R28C42 45 Top of tubesheet R20C43 39 Top of tubesheet R12C44 41 Top of tubesheet R20C47 39 Top of tubesheet R21C57 43 Top of tubesheet R22C57 42 Top of tubesheet R10C58 52 Top of tubesheet STEAM GENERATOR "B" OUTLET R07C36 41 1-1/2" above tubesheet

• The notation " top of tubesheet" refers to defect indications which have been separated from the top of tubesheet eddy current signal using multi-frequency techniques. Twenty-six of these top of tube-sheet signals using a 400 khz eddy current frequency have been present since 1974. The recent development of the multi-frequency eddy current technique has allowed discrimination of defect indications from the top of tubesheet signal. Evaluation of all data available at this time indicates that these top of tubesheet defect indications have been present but undetectable since 1974