ML18052B554

LER 87-015-00:on 870731,capacitor Failed on 1B Reactor Bldg & Refuel Floor Radiation Monitors Resulting in Safety Feature Actuation.Caused by Normal Aging.Capacitor replaced.W/870825 Ltr

ML18052B554
Person / Time
Site:	Quad Cities
Issue date:	08/24/1987
From:	Bax R, Medulan K COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
0370H-0183Z, 370H-183Z, LER-87-015-05, LER-87-15-5, RLB-87-228, NUDOCS 8709010026
Download: ML18052B554 (4)

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AO- ITIE lB Reactor Building and Refuel Floor Radiation Monitors Power Supply Failure (Capacitor)

OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUiREMENTS OF 10CFR MODE (g) CCheck one or more of the following> (11)

_x_ so. 73(a)(2)( iv)

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_ _ _ _ _ _ _..___4_,__+--- 20 .402(b)

_ _ 20.405(c) - 73.7l(b)

_ 73.71(c)

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POWER 20.40S(a)(l)(i) _ S0.3G(c)(1) _ S0.73(a)(2)(v)

_* Other (Specify L~~~~ -1I 0I 0 . ~~::~~~:~~~~~~~!) in Abstract below

%%%%%%%%%%%%%%%%%%%%%%%%%% _ 20 .40S( a) ( 1)(iv) _ so. 73( a)( 2)(ii) _ so. 73(a) (2) (viii) (B) and in Text)

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LICENSEE CONTACT FOR THIS LER l12)

Name 4 - 2 2 4 1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE . SYSTEM COMPONENT MANUFAC- REPORTABLE %%%%%%% CAUSE SYSTEM COMPONENT MANUFAC- REPORT:BLE %%%%%%

T NPR  %%%%%%% T NP D %%%%%%

-=x---t-=-I_.__,L'-+-_......-"'-'-'--'.__~..._.u......:...._.___ _,.___ BB%%% ----+--'---4--_.___.___._-+--_,___.___._--+---- %BB%

SUPPLEMENTAL REPORT EXPECTED (14) Expected Month Day I Year Submission Date (15)

X N ABSTRACT (Limit to 1400 spaces, i.e. approximately fifteen single-space typewritten lines) (16)

On July 31, 1987 Quad Cities Unit One was in the RUN mode at 100 percent rated core thermal power. At 0526 hours0.00609 days <br />0.146 hours <br />8.69709e-4 weeks <br />2.00143e-4 months <br />, the control room ventilation system went to the 100 percent recirculation mode, the Reactor Building Ventilation System isolated, and the l/2A Standby Gas Treatment <SBGT> system automatically started as a result of a loss of the power supply to lB Reactor Building Ventilation and lB Refuel Floor Radiation Monitors. This occurred as designed. This event was reported via the Emergency Notification System <ENS> at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br />.

• The cause for this event was a failed capacitor in the common power supply to the lB Reactor Building Ventilation and. lB Refuel Floor Radiation Monitors. The capacitor failed due to normal aging.

Corrective action for this event was to bypass the lB Reactor Building and Refuel Floor Radiation MonUors and restore the affected systems to normal. Investigation identified the failed capacitor in the power supply and it was replaced like for like. Following replacement, functional tests were satisfactorily performed on both radiation monitors. The monitors were restored to operation at 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> on July 31, 1987. This report is submitted to satisfy the requirements of 10CFR50.73(a)(2)(iv).

~l~ 901 0026 870825 S

• ADOCK 05000254 PDR 1042H

LICENSEE EV,REPQRT !LERI TEXT CONTINUATION

• FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (61 Page D l

• Revision TEXT PLANT AND_ SYSTEM IDENTIFICATION:

General Electric - Boiling Water Reactor - 2511 MWt rated core thermal power. Energy Industry Identification System CEIIS> codes are identified in the text as [XX].

EVENT IDENTIFICATION:

Capacitor failure in the power supply to lB Reactor Building and Refuel Radiation Monitors causes safety feature actuation.

A. CONDITIONS PRIOR TO EVENT:

Unit: One Event Date: July 31, 1987 Event Time: 0526 Reactor Mode: 4 Mode Name: RUN Power Level: 100%

This report was initiated by Deviation Report D-4-1-87-073 Run ModeC4> - In this position the reactor system pressure is at or above 825 psig, and the reactor protection system is energized, with APRM protection and RBM interlocks in service <excluding the 15% high flux scram>.

B. DESCRIPTION OF EVENT:

On July 31, 1987 Quad Cities Unit One was in the RUN mode at 100 percent rated core thermal power. At 0526 hours0.00609 days <br />0.146 hours <br />8.69709e-4 weeks <br />2.00143e-4 months <br />, the following occurred: the control room ventilation system [VI] went to the 100 percent recirculation mode, the Reactor Building Ventilation system [VA] isolated, and the l/2A Standby Gas Treatment <SBGT> system

[BHJ automatically started. These events occurred, as design~d. as a result of the loss of DC power to the lB Reactor Building Ventilation Radiation Monitor [IL, REJ and the Refuel Floor Radiation Monitor [IL, RE]. A loss of power to these instruments caused a high radiation signal spike to be generated from each monitor and this high signal from either monitor caused the above referenced trips. To be assured that the high radiation signals were not valid, the Radiation Chemistry

_Department was notified to initiate local surveys of the affected areas and local readings were found to be in their normal range. Both the lB Reactor Building and lB Refuel Floor Radiation Monitors were reset at this time. Subsequently at 0540 hours0.00625 days <br />0.15 hours <br />8.928571e-4 weeks <br />2.0547e-4 months <br /> the same radiation monitors spiked again. At 0548 hours0.00634 days <br />0.152 hours <br />9.060847e-4 weeks <br />2.08514e-4 months <br /> both radiation monitors were bypassed. At 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> the Reactor Building and Control Room Ventilation systems were returned to normal and the l/2A SBGT was secured.

Because these radiation monitors were now inoperable, QOS 1700-01 <Refueling Floor Ventilation Radiation Montier Inoperable Outabe Report> and QOS 1700-05 <Reactor Building Ventilation Activity Monitor Inoperable Outage Report) were initiated.

This was based on Technical Specification Limiting Conditions for Operation CLCO>

3.2.D'"2., which states that one of the two refueling floor radiation monitors may be inoperable for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. If the inoperable monitor is not restored to service in this time, the reactor building ventilation system shall be isolated and the standby gas treatment operated until repairs are complete.

NRC notification, by the Emergency Notification System <ENS), was completed at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> per 1QCFR50.72.

1042H

LICENSEE EVEN-PQRT (LERJ rm CQNTINUATIQN *..----------

DOCKET NUMBER (2) ~L=ER~NU~M=B=ER~(6~)_ _ _ _ _ _ _ -~P~a=ge.__._(3,._.l~-

Year ~~~ Sequential ~~~

TEXT C. APPARENT CAUSE OF EVENT:

• This report is provided to comply with 10CFR50.73(a)(2)(iv), which requires the reporting of any event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature <ESF).

• The cause of thi ~-event was determined t9 __ ge_j:he __ r~_?_ L__t_gf -~--fA.ili_d ___(snorted) capacffor [CAP]. The failure was the result of end of life. The capacitor is in ft\e**1.:.:1105-7B power supply [JXJ to the Reactor Building Ventilation and Refuel Floor Radiation Monitors. 1he failed capacitor also caused a 250 VDC 1/4 ampere fuse [FUJ to open in this power supply.

D. SAFETY ANALYSIS OF EVENT: When the 'B' channel radiation monitor power supply was lost, it caused the Unit One and Unit Two Reactor Building Ventilation system to isolate, the l/2A SBGT train to start and the control room ventilation system went on recirculation as designed. The A channel of these process radiation monitors was available at all times to provide continuous radiation monitoring and trip capability of the Refuel Floor area and Reactor Building Exhaust ventilation duct. Therefore the safety implications of this event were minimal. E. CORRECTIVE ACTION: A Nuclear Work Request <059171) was written to investigate and repair the l-1705-7B radiation monitor power supply. The faileQ__capacitor was replaced ljke for like. In addition. twg_9ther capacitors <manufacturecroy-Sprague ;*-lt!QdeY-riffmb*er---TvA *1315, 500 uF-50VDC (Cl)), one transistor <model number GE-25 type (C21)), and the*-174 amp

     ?~s~ were ~e~laced f6r preventive maintenance purposes. Both the lB Refuel Floor and Reactor Building Radiation Monitors were then functionally tested in accordance with procedures QIS 34-2 (Reactor Building Ventilation Monitoring Functional Test) and QIS 35-2 <Reactor Building Fuel Pool Radiation Monitoring Functional Test).

Both monitors were returned to service at 1520 hours on July 31, 1987. F. PREVIOUS EVENTS: Licensee Event Report Event Description 254/86-012 Loss of power (inadvertently disconnected) to the lB Refuel Floor and Reactor Building Ventilation. Radiation Monitors caused ESF actuation. 265179-19/032 2A Reactor Building Ventilation Radiation Monitor Power Supply Failure. G. COMPONENT FAILURE DATA: Manufacturer Nomenclature Model Number Sprague *Capacitor TBA 1316, 1000uF-SOVDC(C9) The radiation monitor power supply is manufactured by General Electric, model 1l2C2235Gl. 1042H

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*,           Commonwealth Edison
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'), Quad Cities Nuclear Power Station 22710 206 Avenue North Cordova, Illinois 61242 Telephone 309/654-2241. RLB-87-228 August 25, 1987 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 *

Reference:

Quad-Cities Nucl~ar Pow~r Station Docket Number 50-254, DPR-29, Unit One Enclosed please find Licensee Event Report CLER> 87-015, Revision 00, for Quad-Cities Nuclear Power Station. This report is submitted in accordance 'With the requirements of the Code of Federal Regulations, Title 10, Part 50.73Ca>C2>Civ), which requires the reporting of any event or condition th~t resulted in manual or automatic actuation of any Engineered Safety Feature. Respectful l_y, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION

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R. L. Bax Station Manager RLB/MSK/klm Enclosure cc: I. Johnson R. Higgins INPO Records Center NRC Reg i on II I 0370H/0183Z}}