ML20084E248

AO 50-237/75-13:on 750228,motor Operated Valve 2-1402-24A on Core Spray Sys Failed to Open on Signal from Control Room. Apparently Caused by Interlocking of Valves Rendering Valve Incapable of Being Manually Opened

ML20084E248
Person / Time
Site:	Dresden
Issue date:	03/10/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
150-75, 2780, AO-50-237-75-13, NUDOCS 8304140468
Download: ML20084E248 (4)

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[^ Comm tealth Edison One Firstvfonal Plaza. Chicago. tihnois

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' BBS Ltr. #150-75 Dresden Nuclear Power Station R. R. #1 7 '~2'N l 16rris, Illinois

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March 10, 1975 ~ ,

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j Mr. James G. Keppler, Regional Director Directorate of Regulatory Operations-Region III

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A j U. S. Nuclear Regulatcry Commission .' /

799 Roosevelt Road s.

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SUBJECT:

REFCRT OF /F?CPlub OCCURRE!!CE PFR SECTIO'i 6.6.A 0F THE TECIMICAL SPECIFICATIC:!3 j '1%lLOG OF CO:tB SPRAY VALVE MO-2-1h02-24A TO OPEN 1

! Referenece: 1. Regulatory Guido 1.16 Rov 1 J

1 j 2. Notification of Region III of NRC Regulatory Operations j Telephone: P. Johncon, 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />, March 3, 1975

Telegrcm

J. Koppler, 1055 heurc,Ihrch 4, 1975 i

! 3 Electrical Prints 12E2430 and 12E2431

! Report Nunber: 50-237/1975-13 1

Report Dato: March 10, 1975 j Occurrence Date: February 28, 1975 i

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Facility: Drecden Nuclear Power Staticn, Morris, Illinois i

IDETPIFICATION OF OCCURRDICE 5 On February 28, 1975 at approximately 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br />, motor operated valve l 2-1402-24A on the core cpray system failed to open on a signal from the 1 control room. This was thought to represent a safety system componcnt l- failure which could, cr threaten to, render the system incapable of per-

forming its intended cafety function as defined in the technical specifi-j . cation or S/Jt.

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i CONDITIONS PRIOR TO CCCURRE'!CE 4

f Prior to the occurrence, the reactor was locked in the shutdown mode with

! the replacement of the feedwater cparger and core spray system piping in 1

progress. At this time, all emergency core cooling systems were out of

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service while the above werk was in progress.

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.Mr. James G. Kepple/

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'" March 10, 1975 "1

a DESCRIPYION OF OCCURRM:CE At 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> en February 28,1975, Unit 2 was shutdown for its third refueling outage. During the time of the occurrence, the core spray system was being prepared for draining for subsequent removal of the piping.

The injection valves on A and B core spray systems were being placed back in service to allow opening and subsequent draining. "B" Core Spray system valves opened successihlly and tne line was in the process of being draining.

"A" Core Spray s'/ stem valves, however, did not operate satisfactory. MO 1402-24A failed to open c,n signal from the control room.

DESIGNATION OF APPARDTP CAUSE OF OCCURRE!CE In reviewing the schematic control diagram of the core spray M0 valves, it appears that, with the reactor vessel depressurized, 1402-24A is interlocked with 1402-25A in such a way that it cannot be manually opened from the control room when the 25A valve is open. The interlock, however, does not uork in reverse, in that, with 1402-2hA open, 1402-25A can alco be opened. On "B" system, the operator opened the valves in the 1402-249 and 25B sequence whereas, on "A" system, he opened 1402-25A prior to opening 1402-24A. This resulted in the above occurrence.

At present, the station is unable to verify this conclusion because the valves in question bave their motor operatcra removed.

ANALYSIS OF OCCUPJC;CE The occurrence did not jeopardine the safety of the general public, plant personnel nor the plant components. The plant in its present shutdown mode does not require the cmcrgency core cooling systems to be operational.

In addition, portions of the core spray system piping were removed prior to this occurrence.

CORRFETIVE ACTION The inmediate action by the operations department was to manually crack the valve off its seat and provide another open signal to the valve. It again failed to open.

i l Operations, not knowing the nature of the electrical malfunction, proceeded l to hold in the contactor at the breaker to open the valve. Subsequent to this action, operaticna initiated a work request to determine the malfunction.

j When the core spray valves have their M0's replaced, a surveillance test l will be perfomed on the subject valves to verify operability.

l Any corrective action necessary to be taken to prevent recurrence will be contingent ucon the results of the survcillance tost and will reported in a followup letter.

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• Mr. James G. Keppler n

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March 10, 1975 a

FAILURE DATA To date , t w o previous occurrences involving the Core Spray system were experienced as follows:

1. February 5,1971 - Erchen limit mdtch on 2-1402-243. Corrective action-replaced limit mdtch.

2. Hovember 27, 1974 - Cracks in base plate for limit switch contacts preventint operation on '$-1402-24A. Corrective Action - replaced base plato damaged by water hammer in core spray line.

The valve operator en the subject valve, 2-1402-24A; Limitorque S'G1, Serial number - 70500A.

The valve body is a Grane model 78FJ, 10 inch valve with design conditions of 1250 psi at 575'F. ;__ _[-

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B. B. ;Stephenson Superintendent BBS:IT4:smp File /AEC e

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( 1975 MAR-4 AMil: 42 VED 124 ( 1136)(2-0167 35E063 ) PD 03 /04 /75 1135 I ICS IPMENGZ CSP 9159424449 TDBN MORRIS IL 119 03-04 1136A EST PMS JA"ES G KEPPLER RE3IONAL DIRECTOR CARE DIRECTORI ATE OF REGULATORY

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OPERATION REGION 3 WUX U.S. ATOMIC ENERGY OMMISSION AC __ UT" " ~

799 ROOSEVELI RD 78$ M0dI ,

3LEN ELLYN IL 60137 g-

SUBJECT:

DPR-lo, DRESDEN NUCLEAR P0YER STATION UNIT 2. " '

ATTD T g THIS WILL CONFIRM A CONVERSATION k'ITH PHIL JOHNSON OF YOUTOFFICE AT i

1630 HOURS 3 MARCH CONCERNING FAILURE OF CORE SPRAY MOTOR OPERATED I '

INJECTION VALVE TO OPEN ON 23 FEBRUARY 75 WHEN OPERATIONS ATTEMPTED 5 TO DR AIN THE CORE SPRAY LINE. CORE SPR AY SYSTEM W AS NOT REQUIRED AT

' E THE TIME AND IS OUT OF SERVICE FOR LINE REPLACEMENT. CAUSE IS UNDER l INVESTIGATION.

SF-1201 (RS-69) J IN ADDITION RADIOGRAPHY REVEALED A CRACK IN THE WELD AFTER JUNCTION ON NITROGEN INERTING LINE 2-8503-8 INCH-LX TO DRY YELL VENTILATION -

INLET LINE 2-1604-13 INCH-2. CRACK WAS DISCOVERED 23 FEBRUARY 75 IT WILL BE GROUND OUT AND REPAIRED. CRACK WAS NOT COMPLETELY THROUGH THE WALL.

8 E STEPHENSON SUPERINTENDENT DRESDEN NUCLEAR POWER STATION -

COMMONWEALTH EDISON C0 RR1 MORRIS ILLINDIS 50450 NNNN v 1

SF-1M1 (RW

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