05000281/LER-1976-003, Updated LER 76-03/01T:on 760521,routine Chemistry Analysis of Primary Coolant Boron Concentration Indicated Unplanned Dilution Occurred.Caused by Three Tubes Cut on Steam Generator 2A.Tubes Plugged

Updated LER 76-03/01T:on 760521,routine Chemistry Analysis of Primary Coolant Boron Concentration Indicated Unplanned Dilution Occurred.Caused by Three Tubes Cut on Steam Generator 2A.Tubes Plugged

ML20087A133
Person / Time
Site:	Surry
Issue date:	07/27/1976
From:	Baucom T, Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20087A135	List: 05000281/LER-1976-003, Updated LER 76-03/01T:on 760521,routine Chemistry Analysis of Primary Coolant Boron Concentration Indicated Unplanned Dilution Occurred.Caused by Three Tubes Cut on Steam Generator 2A.Tubes Plugged
References
161, LER-76-03-01T, LER-76-3-1T, NUDOCS 8403070404
Download: ML20087A133 (3)

LER-2076-003, Updated LER 76-03/01T:on 760521,routine Chemistry Analysis of Primary Coolant Boron Concentration Indicated Unplanned Dilution Occurred.Caused by Three Tubes Cut on Steam Generator 2A.Tubes Plugged

Event date:
Report date:
2812076003R00 - NRC Website

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Q UCENSEE EVENT REPO Q asport cate 6-2-76 CONTROL 8 LOCK:I l l I I I I (PLEASE PRINT ALL REGUIRED INFORM ATMN) 1 6 LCENSE NUMBER PE Tv NAME 01 lV l Al Sl Pl Sl2 l l0 l0 l-l 0l 0l 0l 0l0 l-l 0 l 025l l264l 1 l1l1l 0l 30 l 0l 1l 31 32 7 89 14 15 OCCxET NUM9EA EVENT DATE REPCAT OATE CATEGCAY TY P S A O 1 CON'T l Pl 0 l [.T.] (_L] l01510 l-l O l 218l il l Ol Sl2 li I7l 61 88 68 74 l 01 712 17 17 I6l 75 80 7 8 57 58 59 60 61 EVENT DESCRIPTION

$ lWith Unit 2 at cold shutdown followine a refueline. routina chamfatrv snniv=4m of tha80l -

7 89 SE Iorimary coolant boron concentration indicated than an unolanned dilution had occurred.l 7 89 80 3E lThis event is reportable per T.S.6.6.2.A(4). The imediate operator action was to l 7 89 60 HE Iterminate the source of the dilution, which was found to be leakage from the secondarvI 7 89 80 HE I side of 2A steam generator, by securing the auxiliarv steam generator feed (continued)l 7 89 mg 80 SupouER VOLATCN CE CCOE CCMPONENT COCE E IzI zI Lv_J lai TI sI xl Cl al LN_j l W I 1 l 210i 47 Lul 48 7 89 10 11 12 17 43 44 j CAUSE DESCRIPTION GE l Steam Generator "2A" had three tubes which had apparentiv been cut during the removal l

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7 89 80 C l of a section of the seventh tube support plate. When the S/G 1evel was raised above l 7 89 80 EE l the level of the cuts, water passed into the primary side of loop A, which was (Con't)l STA u  % POWER QTHER STATUS dis OVERY DISCOVERY OCSCAIPTON l 0l 0l 0l lz d45 l Routine Chemistry Samoline l h 7 8 l Gl 9 10 12 13 l

44 46 j

30 CF LE E AMOUNT OF ACTMTV LOCATON Cf RELEASE 1

[.2J Ls.J l N/A l l N/A l 7 8 9 10 11 44 45 80 PERSONNEL EXPOSURES NUMe*R TYPE DESCRIPTCN 1 0 1 0l Of l N/A l 1

Lz.J 60 7 89 11 12 13 PEASONNEL INJURIES NUMBEA DESCAiPTON

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l M l 01 Ol 0l l N/A 80 l

7 89 11 12 OFFSITE CONSEQUENCES 1 l N/A l 7 89 80 LOSS OR OAMAGE TO FACIUTY TYPE CESCAePTON 1 [Zj l N/A 80 l

7 89 10

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l ADDITIONAL FACTORS

@ lAnv adverse effect from this dilution could have been negated by boration by the use l 7 89 80 DE l of borated makeup, or via the accumulators. Also since the reactor was-(Continuedl l 7 89 '

90 NAME: T. L. Baucom PHONE: (804) 357-3184 GPO 889 467 L

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EVENT DESCRIPTION (CCNTINUED) pump. An increased analysis frequency of boron concentration was initiated until the source of the dilution water was terminated. (AO-S2-76-03).

CAUSE DESCRIPTION (CCNTINUED) connected to the reactor vessel through a 2" bypass line.

l The boron concentration of the reactor vessel changed from 2396 ppm to a mini-mum of 1836 ppm. This resulted in a minimum shutdown margin of 11.67. as com-pared to a required margin of ly.. The shutdown margin prior to the dilution was 18.37..

Although the dilution was discovered by chemistry analysis, the plant design  ;

incorporates features which would have alerted the operator of a dilution had it been of a magnitude such that a significant reduction in shutdown margin occurred. The increasing audio and metered source range counts, and high-flux-at-shutdown alarm would have alerted the operator to the need for primary sy-stem boration.

The actual faulty tubes resulted from the grinding operation during the tube support plate removal procedure. It was felt that all suspect tubes were cor-rectly plugged, but the additional leaking tubes were created due to close work-ing quarters and conditions. A visual inspection by Westinghouse personnel f ailed to pick up the subject leaking tubes prior to the tube plugging opera-tion. The leaking tubes were plugged to eliminate the leak path. To prevent recurrence of an event of this type, the steam generator close out procedure has.been modified to assure that an adequate leak check on the tubes has been performed prior to securing the steam generator manways. Even though this oc-currence was unique to the tube support plate removal evolution on Unit 2, the procedures for both units were changed.

.T ADDITICNAL FACTORS (CONTINUED) maintaiaed in a shutdown condition by ove: 11% and instrumentation was avail-able to alert the operator of a loss of shutdown margin, there were no adverse safety implications associated with this event. Therefore, this event did not affect the health or safety of the general public.

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.. - s O O IE FILE COPY l VInotarA Ex.ucrarc Ann Powan CoxPAxy Rrcurwoxn.V norxrA 202 01

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l July 30, 1976 2 ' C.'

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Mr. Norman C. Moseley, Director Serial No. 161 Office of Inspection and Enforcement P0&M/ALH:jlf U. S. Nuclear Regulatory Comission Region II - Suite 818 Docket No. 50-28) 230 Peachtree Street, Northwest License No. DPR-32 Atlanta, Georgia 30303

Dear Mr. Moseley:

Pursuant to Surry Power Station Technical Specification 6.6.2, the Virginia Electric and Power Company hereby submits a copy of Licensee Event Report Upd te No. A0-S2-76-03.

The substance of this report has been reviewed by the Station Nuclear Safety and Operating Comittee and will be placed on the agenda for the next -

meeting of the System Nuclear Safety and Operating Cournittee.

Very truly yours, y ,3 3 Q /

, (, , - -i. L lo r * ]*

s C. M. Stallings Vice President-Power Supply and Production Operations Enclosure cc: Mr. Robert W. Reid, Chief (40 copies)

Operating Reactors Branch 4 COPY SENT REGION

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