05000316/LER-1985-033-01, :on 851023,lower Containment Airborne Monitor high-range Noble Gas Channel Gave Spurious High Alarm Signal Resulting in ESF Actuation Signal.Caused by Software Errors. Errors Being Evaluated by Mfg

:on 851023,lower Containment Airborne Monitor high-range Noble Gas Channel Gave Spurious High Alarm Signal Resulting in ESF Actuation Signal.Caused by Software Errors. Errors Being Evaluated by Mfg

ML20137E803
Person / Time
Site:	Cook
Issue date:	11/21/1985
From:	Kriesel T INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
Shared Package
ML20137E676	List: 05000316/LER-1985-031-01, :on 851027,ESF Actuated as Result of Lower Containment Airborne Monitor Particulate Channel Train a High Alarm.Caused by Monitors Trending Upward.Setpoints Readjusted 05000316/LER-1985-032-01, :on 851022,upper Containment Area Radiation Monitor Failed,Resulting in ESF Actuation Signal.Caused by Failure of Two Internal Electronic Modules.Failed Modules Replaced & Monitor Declared Operable 05000316/LER-1985-033-01, :on 851023,lower Containment Airborne Monitor high-range Noble Gas Channel Gave Spurious High Alarm Signal Resulting in ESF Actuation Signal.Caused by Software Errors. Errors Being Evaluated by Mfg 05000316/LER-1985-034-01, :on 851024 & 30,high Alarms Received on Lower Containment Airborne Particulate Radiation Monitor Train B, Resulting in ESF Actuation Signal.Caused by Monitor Trending Upward.Setpoints Readjusted ML20137E669
References
LER-85-033-01, LER-85-33-1, NUDOCS 8511270312
Download: ML20137E803 (2)

LER-1985-033, on 851023,lower Containment Airborne Monitor high-range Noble Gas Channel Gave Spurious High Alarm Signal Resulting in ESF Actuation Signal.Caused by Software Errors. Errors Being Evaluated by Mfg

Event date:
Report date:
3161985033R01 - NRC Website

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484 tract et,-t to F400 aoscas e see,ee+ey, e,*resa pas e spece rose-e twa naes, ites ON OCTOBER 23, 1985 AT 2350 HOURS WITH TIiE REACTOR COOLANT SYSTEM IN MODE 1 (OPERATING) AT 29 PERCENT REACTOR THERMAL POWER, ERS-2309, THE LOWER CONTAINMENT AIRBORNE MONITOR HIGH RANGE NOBLE GAS CHANNEL, (IEEE/ MON) CAVE A SPURIOUS HIGH ALARM SIGNAL.

THE HIGH ALARM RESULTED IN A ESF ACTUATION SIGNAL WHICH WOULD HAVE RESULTED IN AN ISOLATION OF THE CONTAINMENT PURGE SYSTEM HAD THE CONTAINMENT PURGE SYSTEM BEEN IN SERVICE.

THE HIGH ALARM ON ERS-2309 WAS NOT CAUSED BY AN INCREASE IN CONTAINMENT NOBLE GAS LEVELS AS EVIDENCED BY THE RADIATION READINGS AT THE TIME OF THE EVENT.

THE SPURIOUS HIGH ALARM IS THE RESULT OF SOFTWARE ERRORS ASSOCIATED WITH THE NEW EBERLINE MODEL CT-1B SOFTWARE.

THE MANUFACTURER HAS BEEN NOTIFIED OF THE ERROR AND RESOLUTION IS CURRENTLY UNDER EVALUATION.

UPON RESOLUTION THIS LER WILL BE UPDATED.

THE HEALTH AND SAFETY OF THE PUBLIC WAS NOT AFFECTED.

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NRC fem 3a.A U S. NUCLEJ.R REGUL ATolY COMMIS$10N LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Areaovfo oMe No siso-oio4 EXPtRES 8/3125 P ACILITY NAME (1)

DOCKET NUMSER (2)

LER NUMBER (6)

PAGE(3)

" Ma" WM D. C. COOK NUCLEAR PLANT UNIT 2 o ls l0 l0 l0 l 3l1l t 8l 5 0l 3l 3 0l0 0 l2 OF 0l 2 ftXT IM more spece e mrunet use ea&Donel NRC Form 366Ksl(1h ON OCTOBER 23, 1985 AT 2350 HOURS WITH THE REACTOR COOLANT SYSTEM IN MODE 1 (OPERATING) AT 29 PERCENT REACTOR THERMAL POWER, ERS-2309, THE LOWER CONTAINMENT AIRBORNE MONITOR HIGH RANGE NOBLE GAS CHANNEL (IEEE/ MON) GAVE A SPURIOUS HIGH ALARM SIGNAL.

THE HIGH ALARM RESULTED IN AN ESF ACTUATION WHICH WOULD HAVE RESULTED IN AN ISOLATION OF THE CONTAINMENT PURGE SYSTEM HAD THE CONTAINMENT PURGE SYSTEM BEEN IN SERVICE.

THE HIGH ALARM ON ERS-2309 WAS NOT CAUSED BY AN INCREASE IN CONTAINMENT NOBLE GAS LEVELS.

THE RECORDED VALUE FOR THE CHANNEL AT THE TIME OF THE HIGH ALARM WAS 1.73 E+00 MICRO Ci/cc.

IN ADDITION, NO HIGH ALARMS WERE RECEIVED ON THE LOW OR MID RANGE NOBLE GAS CHANNELS AS WOULD BE EXPECTED HAD A REAL INCREASE IN CONTAINMENT RADIOACTIVITY OF LARGE PROPORTION OCCURRED.

THE HIGH ALARM APPEARS TO BE ASSOCIATED WITH THE CLOCK AND CONTROLLER SYNCHRONIZATION THAT OCCUR ON THE CONTROL TERMINAL AROUND MIDNIGHT.

THE CONTROL TERMINAL AND EACH MONITOR HAVE INDEPENDENT INTERNAL CLOCKS WHICH RECEIVE A CLOCK SYNCHRONIZATION MESSAGE FROM THE CONTROL TERMINAL SOFTWARE EACH NIGHT AT APPROXIMATELY MIDNIGHT.

WHEN ANY MONITOR IS NOT IN SYNCHRONIZATION, THE SOFTWARE ATTEMPTS TO FIT ANY DATA PRESENT IN THE CHANNEL INTO AN ARBITRARY TIME FRAME.

THIS CAN RESULT IN A FALSE CHANNEL STATUS WHICH MAY OR MAY NOT BE A HIGH ALARM.

THE CLOCK SYNCHRONIZATION PROBLEM IS A SOFTWARE ERROR ASSOCIATED WITH THE NEW EBERLINE MODEL CT-1B SOFTWARE.

THE MANUFACTURER HAS BEEN NOTIFIED Oi THE ERROR AND RESOLUTION IS CURRENTLY UNDER EVALUATION.

UPON REETLUTION THIS LER WILL BE UPDATED.

THE HEALTH AND SAFETY OF THE PUBLIC WAS NOT AFFECTED.

PREVIOUS OCCURRENCES OF A SIMILAR EVENT INCLUDE:

316/84-011; 316/84-008.

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