05000315/LER-1985-035, :on 850729,RCS Boron Concentration Determined Below Tech Spec Requirement of 2000 Ppm.Cause Unidentified. RCS Immediately Borated to 2128 Ppm.Chemical Sampling Frequency Increased & Operations Order Issued

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:on 850729,RCS Boron Concentration Determined Below Tech Spec Requirement of 2000 Ppm.Cause Unidentified. RCS Immediately Borated to 2128 Ppm.Chemical Sampling Frequency Increased & Operations Order Issued
ML20134N686
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 08/27/1985
From: Blind A
INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
Shared Package
ML20134N681 List:
References
LER-85-035, LER-85-35, NUDOCS 8509050275
Download: ML20134N686 (2)
v • d • e


LER-1985-035, on 850729,RCS Boron Concentration Determined Below Tech Spec Requirement of 2000 Ppm.Cause Unidentified. RCS Immediately Borated to 2128 Ppm.Chemical Sampling Frequency Increased & Operations Order Issued
Event date:
Report date:
3151985035R00 - NRC Website
v • d • e

text

f NPC de,m 300 U 8. NUCLE 12 $_E1ULATO.JY COMMIS810N f9431 APPROvtD OMS NO 3190- @ 04 LICENSEE EVENT REPORT (LER)

F ACitlTY NAME tH DOCKET NUMGER Irl PAGEil D.C. COOK NUCLEAR PLANT, UNIT 1 0 l5 l 0 l010 l 3l1 l 5 1 lOFl 012 76TLE 144 UNEXPLAINED REACTOR COOLANT SYSTEM DILUTION EVENT DATI 15)

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W JULY 29,1985, UNIT 1 WAS IN MODE 6 (REEUELING), WITH THE REACIOR VESSEL HEAD SEATED AND 'ITE REACIOR COOLANT SYSTEM (RCS) FTT.Tm 'IO 'IIIE HALF-ICOP LEVEL. AT 0230 HOURS ON THAT DATE, IT WAS DETERMINED THAT UNIT 1 RCS BORON CONCENTRATION WAS 1967 PPM. 'IHIS IS NONOONSERVATIVE WITH RESPET 'IO TECHNICAL SPECIFICATION 3.9.1, WHICH REQUIRES THAT A CONCENTRATION OF 2000 PPM BE MAINTAINED. 'I1E RCS WAS IMEDIATELY BORATED 'IO A CONCENTRATION OF 2012 PPM. AT 0923 HOURS, StFPLE RESULTS AGAIN INDICATED THAT 'ITE RCS BORON CONCENTRATION HAD FAT. TEN RFTfM 2000 PPM. TIE RCS WAS IMEDIATELY BORATED FROM 1972 PPM 'IO 2128 PPM. SUBSEQUENT SAMPLE RESULTS INDICATED NO FURI11ER DECREASE IN BORON CONCENTRATION.

AN INVESTIGATICU OF THE EVENT FATim 'IO DETERMINE THE SOURCE OF TIE APPARENT DILUTI m.

AN OPERATIONS STANDING ORDER HAS BEEN ISSUED 'IO ELIMINATE WE POSSTRTR SOURCE OF THE RCS BORN CONCENTRATIm DECREASE. NO OIEER POSSTRTE SOURCE WAS IDENTIFIED 'IO AN EXTENT HHICH WOULD JUSTIFY IMPLMENTATION OF ADDITIQUE PREVENTIVE ACTIONS.

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?U S. NUCLEAR REGULATOAY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AreROvEo oms No. 3 iso-oio4 ExelRES 83115 F ACILITY NAME til DOCKET NUM8ER 121 LER NUMBER 16)

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sa D.C. COOK PLANT - UNIT 1 0 l5 l0 l0 l0 l 3l1l5 8[5 0l3l5 0l0 0l2 0F 0 l2 TEXT tM more space a renewed use s#eone! NRC Form ki6Ks)(17) m JULY 29,1985, UNIT 1 NAS IN FEDE 6 (REFUELING), WITH THE REACIOR VESSEL HEAD SEATED AND TIE REACIOR COOLANT SYSTEM (RCS) FIILED 'IO THE HALF-IDOP LEVEL. AT 0230 HOURS ON THAT DATE, IT NAS DETERMINED HIAT UNIT 1 RCS BORON CONCENTRATION NAS 1967 PPM. THIS IS NWCONSERVATIVE WITH RESPECT 'IO TECHNICAL SPECIFICATION 3.9.1, NHICH REQUIRES HIAT A CONCENTRATION OF 2000 PPM BE MAINTAINED. THE RCS NAS IMMEDIATELY BORATED 'IO A CONCENTRATION OF 2012 PPM. AT 0923 HOURS, SAMPLE RESULTS PCAtti INDICATED DIAT HIE RCS BORON CONCEtERATION HAD FALLEN BEION 2000 PPM. THE RCS NAS IIHEDIATELY BORATED FROM 1972 'IO 2128 PPM. SUBSEQUENT SAMPLE RESULTS INDICATED NO FURTHER DECREASE IN BORON CONCENTRATIW.

AN INVESTIGATION NAS CONDUCTED TO DETERMINE THE SOURCE OF THE APPARENT RCS DIIIRICN. EOLLOWING EXAMINATION OF SAMPLE RESULTS, RECORDER CHARTS, IOGS, AND PERSONNEL STATDEES, THE SOURCE OF TiiE DILUTION RDRINS UNIDENTIFIED. CIOSE EXAMINATION OF SOURCE RANGE NUCLEAR INSTRUMENTATION CHAIES INDICATES MIAT THE PRESUMED DILUTI m OOCURRED FROM APPROXIFETELY 1615 HOURS ON JULY 28, 1985, 'IO APPROXIbETELY 0630 HOURS ON JULY 29, 1985.

THIS EVENT NAS SION IN DEVEIDPING AND NAS IDENTIFIED BY ROUTINE CHEMICAL SAMPLING. ON IDENTIFICATIN OF DE PROBLEM, SAMPLING h<tVJtNCY NAS INCREASED.

BORATION EQUIPMENT NAS AVAIIABLE AND WAS USED PRCMPTLY AND tmrnVELY 'IO COUNTER THE BORCN CONCENTRATION DECREASE. BASED ON THE ABOVE CIRCUMSTANCES AND TIE FACT THAT BORCN CONCENTRATION DID NOT APPROACH THE MINIMUM CONCENTRATION REQUIRED 'IO MAINTAIN ACCEPTABLE SHUIDOWN MARGIN (1565 PPM BY FLEL VENDOR CALCULATION), IT IS CONCLUDED THAT PUBLIC IEALDI AND SAFETY NERE NOT Arrtum BY HIIS EVENT.

OPERATICNS STANDING ORDER 067 REQUIRES THAT EFFORTS BE MADE 'IO MAINTAIN RCS, REFUELING CAVITY, AND TRANSFER CANAL BORON CONCEtERATION AT OR GREATER MIAN 2000 PPM DURING PERIODS HHEN NO FUEL IS IN DE REACIOR VESSEL. THIS STANDING ORDER NAS ISSUED 'IO ELIMINATE ONE POSSIBLE SWRCE OF HE RCS BORON CCNCENTRATIm DEI'REASE.

NO OTHER POSSIBLE SOURCE NAS IDENTIFIED 'IO AN EXTENT MIICH NOULD JUSTIFY IMPLEMENTATION OF ADDITIONAL PREVENTIVE ACTIONS.

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