ML20023B593

LER 83-029/03L-0:on 830402,during Mode 4,automatic Actuation of ECCS Occurred.Caused by Maint Personnel Standing on Conduit Resulting in Loss of lo-lo Pressurizer Pressure Safety Injection Block.Maint Personnel Reinstructed

ML20023B593
Person / Time
Site:	North Anna
Issue date:	04/27/1983
From:	Harrell E VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20023B588	List: ML20023B587 ML20023B593
References
LER-83-029-03L, LER-83-29-3L, NUDOCS 8305050215
Download: ML20023B593 (3)

Text

_ _ _ _ _ _ . - _ - ._ _ _ _ - __ __ _ __ _ . .

.. 4 U.S. NUCLEAR RECULATORY COMMISSION LICENSEE EVENT REPORT h

CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/ /V/A/N/A/S/2/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) /4/1/1/1/1/ (4) / / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT IUlI#

$U$f_L/(6) g /0/5/0/0/0/3/3/9/ (7) /0/4/0/2/8/3/ (8) /0/4/2/7/8/3/ (9)

DOCKET NUMBER EVENT DATE REPORT DATE-EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10).

/0/2/ / On March 2, 1983 with Unit 2 in Mode 4 an automatic actuation'of the Emergency /

/0/3/ / Core Cooling System occurred due to the loss of a Lo-Lo Pressurizer Pressure'S.I./

-/0/4/ / Block. During the event pressurizer power operated relief valve PCV-2456 lifted /

/0/5/ / twice. At no time during the event did actual plant parameters require an ECCS /

, /0/6/ / actuation therefore the health and safety of the public were not affected. This /

/0/7/ / event is reportable pursuant to T.S. 6.9.1.9.b and T.S. 6.9.2. /

/0/8/ / /

. SYSTEM CAUSE CAUSE COMP. VALVE.

l CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/ /S/F/ (11) /X/ (12) /Z/ (13) /Z/Z/Z/Z/Z/Z/ /Z/ /Z/

SEQUENTIAL OCCURRENCE REPORT REVISION LER/RO EVENT YEAR REPORT NO. CODE TYPE NO.

f (17) REPORT i NUMBER /8/3/ /-/ /0/2/9/ / / /0/3/ /L/ /-/ /0/

! ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT j .TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/X/ (18) _/Z/ (19)

. _/Z/ (20) _/Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) /Z/ (25) /Z/9/9/9/ _ _ _

! CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27) l

/1/0/ / The ECCS actuation was due to the loss of'Lo-Lo Pressurizer Pressure S.I. Block._/

/1/1/ / PCV-2456 lif ted when pressurizer pressure reached its low temperature setpoint of/

/1/2/ / 470 psig due to the influx of injection water. The loss of block was caused by a/

/1/3/ / SSPS train "B" power supply spike. /

/1/4/ / ,

/

FACILITY METHOD OF STATUS  % POWER DISCOVERY DISCOVERY DESCRIPTION (32)

/1/5/ OTHER STATUS (

/G/ (28) /0/0/0/ (29) / NA / /A/ (31) / Operator Observation /

ACTIVITY CONTENT RELEASED _0F RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)

/1/6/ /Z/ (33) /Z/ (34) / NA / / NA /

PERSONNEL EXPOSURES .

NUMBER . TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) /Z/ (38) / NA /

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40)' / NA /

LOSS OF OR DAMAGE TO FACILITY (43) PDR 8305050215 830427

-TYPE DESCRIPTION ADOCM 05000339

/1/9/ S

/Z/ (42) / NA PDR /

( PUBLICITY l ISSUED DESCRIPTION (45) NRC USE ONLY l

/2/0/ /N/ (44) / NA /////////////

i NAME OF PREPARER E. WAYNE HARRELL PHONE (703) 894-5151 *

.- i f a Virginia Electric and Power Company North Anna Power Station Unit No. 2

Attachment:

Page 1 of 2 Docket No. 50-339 Report No. LER 83-029/03L-0 Description of Event On March 2, 1983, at 2009 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.644245e-4 months <br /> with Unit 2 in Mode 4 cooling down for refueling, an automatic actuation of the Emergency Core Cooling System occurred due to the loss of the Lo-Lo Pressurizer Pressure Safety Injection Block in the train "B" logic of the Solid State Protection System. Initial conditions of the Reactor Coolant System were as follows; RCS Temperature 321*F, Pressurizer Pressure 410 PSIG and Pressurizer Level 20 percent. Upon inj ection of water into the RCS pressurizer pressure and level increased rapidly. At 2011 and 2012 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.65566e-4 months <br /> power operated relief valve, PCV-2456, lifted at its low temperature over pressure protection setpoint of 470 psig. Safety injection was reset at 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br /> and the injection flow terminated.

During the event the refueling water storage tank dropped below T.S.

minimum level and control bottle air banks discharged, both normal conditions during a safety injection. All equipment performed as designed during the event except breaker 25C6, power supply breaker to main S/G feedwater pump motor 2-FW-P-102. This event is reportable pursuant to T.S. 6.9.1.9.b and serves as a special report in accordance with T.S. 3.4.9.3 action C and T.S. 3.5.3 action C reportable pursuant to T.S. 6.9.2. This was the fifth S.I. to occur on Unit 2.

Probable Consequences of Occurrence The Emergency Core Cooling System is designed to inject borated water into the Reactor Coolant System and maintain coolant inventory in the event of a loss of coolant accident or rapid cooldown from a main steam line break. Since the ECCS System and related equipment performed as required and an actual condition requiring the ECCS did not occur the health and safety of the public were not affected.

Breaker 25C6 trip is part of the main S/G feedwater isolation.

Since isolation valves associated with the isolation of the feedpumps did close the health and safety of the public were not affected.

Cause of Occurrence The power supply to the Solid State Protection System train "B" logic cabinet is provided by two redundant power supplies to assure a positive power source to the logic cards. Number one power supply is fed from 120 VAC Vital bus 2-III and number two power supply is fed from 120 VAC Vital bus 2-IV. Seventeen minutes prior to the receipt of the Emergency Core Cooling actuation a SSPS train " P," trouble alarm was received in the main Control Room. Upon investigation it was determined that the alarm was brought in by a blown fuse in the power supply line from 120 VAC Vital bus 2-IV to the number two D.C. power supply. The fuse blew because of a short to ground in the number four turbine i throttle valve limit switch. The short was caused by maintenance personnel standing on the conduit to the limit switch while performing maintenance.

e ,k

Attachment:

Page 2 of 2 The loss of power to SSPS train "B" from 120 VAC Vital bus 2-lV left only one D.C. power supply to the logic cabinet. A power supply spike is the suspected cause of the loss of the Lo-Lo pressurizer pressure block. The cause of the suspected spike in 120 VAC bus 2-III was investigated and could not be determined.

The failure of breaker 25C6 to trip on ECCS actuation is under investigation and will be repaired prior to re-entering Mode 4.

Immediate Corrective Action Immediate corrective actions were to restore the Refueling Water Storage Tank level and Control Room bottled air to operable status in accordance with their associated T.S. Action Statements. Maintenance personnel involved were reinstructed upon the dangers of using conduit for supports.

Scheduled Corrective Action Determine cause of failure of 25C6 to trip on an ECCS actuation and repair prior to re-entering Mode 4.

Actions Taken to Prevent Recurrence None required.

Generic Implications None

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