ML19305D735

LER 80-007/03L-0:on 800308,while Performing Control Room Insp & Panel Check,B Main Steam Line Radiation Monitor Found Reading Low.Caused by Logarithmic Radiation Monitor Chassis Electronically Drifting Out of Calibr.Chassis Recalibr

ML19305D735
Person / Time
Site:	Quad Cities
Issue date:	03/25/1980
From:	Wykoff D COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19305D732	List: ML19305D731 ML19305D735
References
LER-80-007-03L-02, LER-80-7-3L-2, NUDOCS 8004150467
Download: ML19305D735 (2)

Text

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NRC FORM 386 U. S. NUCLEAR REGULATORY COMMISSION

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LICENSEE EVENT REPORT.

CONTROL BLOCK: l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

f' T'l l8 l9 I L LICENSEE 7 l a l ^CODE l o 11 J@15 01 01UCENSE 14 01 NUM8ER

-l01 0101-1010101@ 25 28 UCENSE 41111li11l@l TYPE JO I

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ITTil Ou% L_t_J@l0 i s DOCKET 1010NUMB 10 ER12 is l468l@l69 013EVENT I O DATE I 8 I 8 i 01@l74 75 01312 l s I 81080l@

REPORT DATE 7 8 60 61 ,

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h ml While performing the Normal Control Poom inspection and Shift Turnover Panel Check. I  ;

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gl procedure QOS 005-2, the B main steam line radiation monitor was found to be reading l l

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io ;4; l low. An instrument problem resulting in a lower than normal reading could cause the Bl

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o 3 l system to trip at a radiation level greater than those established by Technical I i

g o is l l Specification 3 1.

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The reJandant A, C, and D main steam line monitors were operating i  !

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fB T- I l normally and would have provided the required high radiation level setpoint trip l lO la l I functions. l ,

7 8 9 80 0E OE SU C E COMPONENT CODE SUSCodE SU E 7

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9 to 11

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,,, SEQUENTIAL OCCURRENCE REPORT REVISION

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LE R/RO EVENT YEAR REPORT NO. CODE TYPE N O.

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27 l0 l3 l 28 29

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f N AC ON O NT ME HOURS 22 SS I FOR B. SU Lt MANUFA RER l Elgl34Zlg Jg 33 35 W@

36 l0l0l0l0l 37 lYl@ ]g 41 lN l@ lG l0 l8 l0 l 40 - 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i l 0 l l The B logarithmic radiation monitor chassis electronically drif ted out of l ,

, gl calibration, lhe instrument chassis was recalibrated and functionally tested I ii l 2 I l satisfactorily. ll l 11131 I l Lt l.,4 ] I l l 7 8 9 80 STA  % POWER OTHER STATUS 01 O Y DISCOVERY DESCRIPTION l t 5

(_E_l @ l 0 l 9 1 6 l @ l NA l lAl@l Operational Event I!

A TIVITY CO TENT l AMOUNT OF ACTIVITY LOCATION OF RELEASE l 1 6 RELEASE

(,,_Z_j @D OP RELEASE NA [Z_j@l I l NA l

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PERSONNEL EXPOS ES NUM8ER TYPE DESCRIPTION

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• I0l0l0l@lZl@l NA l PERSONNE L INJU IES NUMBER DETCRIPTION 7

i a 8 9 10l0l0l@l 11 12 NA 80 l

, LOSS OF OR DAMAGE TO FACILITY

! TYPE DESCRIPTION

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2 O ISSUEJ8l LN E CRIPTION NA q o pa y e: n g,,.h"'l'2 l lllllllllllll;

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NAME OF PREPARER

• PHONE: 3M6-2241 en.1% {

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l. LER NUMBER: LER/R0 80-07/03L-0  !

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11. LICENSEE NAME: Comnonweal th Edison Company Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit One

IV. DOCKET NUMBER: 050-254

• V. EVENT DESCRIPTION:

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On March 8, 1980, while performing Procedure QOS 005-2, Normal Control Room inspection and Shif t Turnover Panel Check, the Unit One B main steam line radiation monitor was found to be reading low. The B main steam line radiation monitor. was ,

reading about 50 millirem per hour while the A, C and D main steam line radiation monitors were reading about 100 millirem  ;

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per hour. The low reading on the B main steam line radiation monitor was determined to be the result of the B logarithmic radiation monitor chassis being out of calibration. This  !

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would cause the B system to trip at a radiation level greater than or equal to seven times the background radiation level  ;

(Technical Specification 3.1, Table 3 1-3). '

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VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

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The safety implications of this event are minimal. The A, C 7 and D main steam line radiation monitoring systems were operational and would have provided the required trips on a high radiation level.

• Vll. CAUSE:

The cause of this occurrence was equipment failure. The B logarithmic radiation monitor chassis electronically drif ted out of cailbration. The logarithmic radlaiton monitor chassis is a General Electric model 194X629G7 monitor, with a range of zero to one million millirem per hour.

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l Vill. CORRECTIVE ACTION:

An instrument mechanic was immediately called to recalibrate the B logarithmic radiation monitor chassis. Thc instrument mechanic calibrated and functionally tested the B logarithmic radiation monitor chassis in accordance with procedure QlS 31-1, Main Steam Line Radiation-Log Rad Monitor Chassis - S.T. -

31A. No further corrective actions were deemed necessary-to

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prevent recurrence. Surveillance procedure QOS 005-2 verified that the other logarithmic radiation monitor chassis were ,

acceptable.

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