ML20042G769

LER 90-005-00:on 900410,steam Generator Tube Eddy Current Exam Yielded Insp Category C-3 Results.Caused by Primary Water Stress Corrosion Cracking in Hot Leg Tubesheet Area. Defective Tubes Plugged or repaired.W/900508 Ltr

ML20042G769
Person / Time
Site:	Summer
Issue date:	05/08/1990
From:	Bradham O, Higgins W SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-005, LER-90-5, NUDOCS 9005160066
Download: ML20042G769 (4)

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May 8, 1990' i ! Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 LER 90-005 Gentlemen: Attached is Licensee Event Report No. 90-005 for the Virgil C. Summer Nuclear Station. This report is submitted pursuant to the requirements of Technical SpecificationSection4.4.5.5.cand10CFR50.73(a)(2)(ii). Should there be any questions, please call us at your convenience. Very truly yours, y +W

0. S. Bradham ARR/0SB: led Attachment

                       'c:    0. W. Dixon, Jr./T. C. Nichols, Jr.

E.'C. Roberts R. V. Tanner J. C. Snelson S. D. Ebneter R. L. Prevatte J. J. Hayes, Jr. J. B. Knotts, Jr. General Managers INP0 Records Center 1 C. A. Price ANI Library G. J. Taylor Marsh & McLennan J. R. Proper NSRC R. B. Clary NPCF F.~H. Zander RTS (0NO900043) T. L. Matlosz Files (818.05 & 818.07) K. E. Nodland 9005160066 900508 f/ PDR ADOCK 05000395 l S PDC g\

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                                                                                                                                                                               ' " " " " '"5 LICENSEE EVENT REPORT (LER)

[ DOCKf f NUM9t h (21 PAGE I3i facitiTV h&Mt nl Virgil C. Summer Nuclear Station o is i o io i o 131915 1 lorl013 1 1L8 i41 Steam Generator Tube Eddy Current Results - Category C-3 Applied _

                                                                                                       '                                               OTHER f ACILifitt INVOLVED 181 iVENT DATS (Si                           LtR septeelR iGI                                           REPDAT DATI (Fi DAY       YEAR        YEAR 550 g (A 6 at                  pgq9g      pg,      yggp               g A C8417 Y h AMit                DOCkti hvM8tR'5>

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0 l4 110 90 9l 0 0l0l5 0l0 0l 5 0l8 9\0 o isio io ioi i i tuis REPORT is sveMiTTto evRouaNT to THE RioviREMENTs os 10 Co A a reaece ea. e,,ae,e er ra. #eue.mer tiis "oos ai 6 n .0mi n oi.i .0 n.H Hi u nmi nwei g _ n oi.in Ha

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50 73teH2HviuMBI to e06 tait 1Hiel { 50.73teH2Hal SO 73isH2Hal 20 405 sinHul 50 T3teH2 Hint LICIN8it CONT ACT FOR TMiB Lim n2n Ngug TELEPHONI NUM84R art A C005 W. R. Hiagins, Supervisor, Regulatory Compliance 81013 3l415i-1410 412 COMPLEf t ONE LINE FOR E ACH COMPONENT F AILURE DESChittD IN THl$ REPORT n)) REPORTA E Y - i CAust Sv8 TEM covPON6NT MQ8jC p CAvst $Y ST E M COMPQNENT g H 4,#0 pp RTa i i i i i i N i , 1 i i i i i i l l 1 l l 1 1 I I I I I 1 BUPPLEMENTAL REPORY E RPICTED nel MONTH Day YEAR YES tit vee some,m EJiptCit0 Sv0wsst0N DA Til ko l l l A u f R A C T < t , , ,e , = ,e . . . . . . , ,, ,, . . ... ~ ,.. ,--, n . , On April 18, 1990, at approximately 1130 hours the preliminary results of the fifth inservice eddy current examination of the Virgil C. Summer Nuclear Station steam generators were completed. The planned examinations included 100% of the available (i.e., not plugged) tubes in each steam generator hot leg tubesheet. The inspections were conducted using diaital multifrequency techniques. The results indicated that since more than 1% of the inspected tubes in each steam generator were defective, a C-3 inspection category per Technical Specification 4.4.5.2, applied. When each steam generator entered C.tegory C-3, a prompt notification was made to the NRC Operations Center per the requirements of Technical Specification 4.4.5.5 and 10CFR50.72(b)(2)(i). The final results of the inspections performed during the fifth refueling outage were as follows: Steam Generator # of Tubes Pluaaed # of Tubes Repaired A 88 76 B 110 49 C 81 0 The Category C-3 tube degradation is localized in the tubesheet area and is the result of Primary Water Stress Corrosion Cracking (PWSCC). Tube plugging or repair, as appropriate, was completed on April 29, 1990. (c,...-

t esRC Perm 3840; . U.8 NUCLEQR QEQULQT0QY COMMitSION 9 ' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION mRovf o oc ho mo-oio4 - r a [#~-

                                                                                                                                                                              $1PtRi$ S/3)f85 PActLITY MML H)                                                                                          DOCKET NUMBER (3)                                 LER NUMalR (6)                 Pact (31 vtaa                         'Tt",7          O AT:

Virgil C. Summer Nuclear Station 01610 l o l o 1319 l 5 910 - 01Ol5 -- 010 0 l7 oF gl3 itXT W more wete 6 mquired, var ed6tener MC form 386Kel(1h PLANT IDENTIFICATION:- Westinghouse - Pressurized Water Reactor EQUIPMENT IDENTIFICATION: Westinghouse Model D-3 Steam Generators (SG) Reactor Coolant System - AB - Ells IDENTIFICATION OF EVENT: Steam generator tube eddy current examinations yield inspection category C-3 results in the hot leg tubesheet area, i.e., greater than 1% of the inspected tubes in each generator were defective with defects localized in the tubesheet area. EVENT DATE: April 10, 1990, at approximately 1707 hours. REPORT 04TE: May 8,.1990 This is-the followup report-to the 10CFR50.72 notification required by Section 4.4.5.5.of the Virgil C. Summer Nuclear Station Technical Specifications. The initial notification was made as. required by Technical Specifications 4.4.5.5 upon entry into category C-3 by each steam generator (SG "C" April 10, 1990, at 1707 hours, SG'"B" April 11, 1990, at

         - 0905-. hours, and SG "A" April 12,1990,at0915 hours).

This. report was initiated by Off-Normal Occurrence report 90-043.

          -PREVIOUS SIMILAR EVENTS:

Previous eddy current inspections have yielded similar results and have been reported to the.NRC in LER 85-031 submitted on November 13, 1985, LER 87-006 submitted on May 7, 1987, and LER 88-011 submitted on November 23, 1988. CONDITIONS PRIOR TO THE EVENT: 0%. Power - Fifth Refueling Outage DESCRIPTION OF EVENT: The'fifth' inservice eddy current examination of the Virgil C. Summer Nuclear Station steam generator tubing was performed during April 1990. The examination was performed in , accordance with the ASME " Boiler and Pressure Vessel Code" Section XI, 1977 edition. l

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• 8eRC Form as4A U S NUCLE AR KEQULATOM COMMIS8t0N LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AamovEc oMe ao mo-eto4 e 'N ... E KPIRES $l31186 PRCluT V hAME (1) DOCetti NUMBE A (2) LER NUMBER (64 Pt.CE (31 n= "C::W,*'  %'u:

Virgil C. Saner Nuclear Station 0 P lo lo 10 l3 l 915 910 - 01015 - 01 0 01 3 oF 0l3 1tKT (11 more apace 8 requered, use addrtonal MfC fwm 3tsA s)(1h through Summer 1978 addenda, and as specified by Regulatory Guide 1.83 Revision 1, July 1975. The examination was performed on 100% of the available tubing (i.e., unplugged) in r the inlet (i.e., hot leg) tubesheet region. Also, the inner row tubes, rows 1 and 2, and tubes in rows 7 through 11 were inspected, as a minimum, from the end of the tube on the inlet side through the top support plate on the outlet side. In addition, 17% of the available tubes had a full length exuination performed (i.e., from the tube end on the inlet side through the tube end on the outlet side). This included the preheater area and a random sample of the remaining tube bundle. The examination was conducted using digital multifrequency techniques. On April 18, 1990, at approximately 1130 hours, the eddy current examinations were completed and the results yielded an inspection category C-3 determination since more than 1% of the tubes in the hot leg tubesheet region were defective. Prompt notification of the results was made to the NRC Operations Center upon entry into category C-3 of each steam generator. The notification was made per the requirements of Technical Specification Section 4.4.5.5 and 10CFR50.72(b)(2)(i). On April 29, 1990, tube plugging or repair of defective tubes was completed. CAUSE OF EVENT: The category C-3 tube degradation is the result of Primary Water Stress Corrosion Cracking (PWSCC) in the hot leg tubesheet area. ANAL.YSIS OF EVENT: The eddy current inspections yielded results that were consistent with what had been projected by SCE&G personnel based on past inspection results. By performing tube plugging or repair in accordance with Technical Specification requirements, defective tubes were removed from service or repaired, thereby ensuring that there was no reduction in the degree of protection provided to the public. l l CORRECTIVE ACTIONS: l L 'All defective tubes were plugged or repaired in accordance with Technical Specification

requirements. A small number of pluggable indications were found in the cold leg l tubesheet area, the first support plate on the hot leg side and in the preheater area.

(The cause of these indications was PWSCC, Outer Diameter Stress Corrosion Cracking and wear,respectively.) Also, as a preventive measure, 7 tubes had Westinghouse cable dampers installed to address potential concerns resulting from a lack of anti-vibration bar support. Subsequent inservice inspections will be performed as reluired by the VCSNS i Technical Specifications. 4,o.M uu =}}