ML20042G720

LER 90-012-00:on 900406,review of Steam Generator Blowdown Monitor High Radiation Alarm Setpoint Revealed That Setpoint Was Nonconservative.Caused by Administrative Deficiency. Correct Setpoint installed.W/900507 Ltr

ML20042G720
Person / Time
Site:	Millstone
Issue date:	05/07/1990
From:	Conway R, Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-012, MP-90-455, NUDOCS 9005160011
Download: ML20042G720 (4)

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' 'O gggg Genera! Offices'Selden Street, Berhn Connecticut h wY N.'*sIeN tiNeet cN*n7 P.O. BOX 270 rI$*.sid' Utis i *Erv c7E*o'Uany HARTFORD. CONNECTICUT 06414-0270 tRwtheast Nucioa' Enroy Cornpany (203)666-6000 May 7, 1990 MP-90-455 Re: 10CFR50.73(a)(2)(i)

U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Reference:

Facility Operating License No. NPF-49 Dockei No. 50-423 Licensee Event Report 90-012-00 Gentlemen:

This letter forwards Licensee Event Report 90-012-00, required to be submitted within-thirty (30) days pursuant to 10CFR50.73(a)(2)(i), any operation or condition prohibited by the Plant's Technical Specifications.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY l

' St h btE. Scace tw o Director, Millstone Statien SES/RDC:mo

Attachment:

LER 90-012-00 cc: T. T. Martin, Region 1 Administrator W. J.' Raymond, Senior Resident inspector, Millstone Unit Nos.1, 2 and 3 D. H. Jaffe, NRC Project Manager, Millstone Unit No. 3 i

0 900D160011 900507 PDR S ADOCK 05000423 PDC $

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F ACUTY NAME (1) hiillstone Nuclear Power Station Unit 3 0l6lof0!Oldl213 1loFl 0] 3 181 L% ial Non-Conservathe Blowdown Radiation hionitor Setroint Due to Administrative Deficiency EVENT oAtf isi t re. N;iune n ,6i Prpont n*Tr nTi etwrn r Acitivir s iNvot vro <ri VoNTF DAY YEAR YEAR MONT H day YEAA F AOUTY NAMES i of sl ol 01 of I I

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SUPPLf MENT AL AEp0AT FxPECTED ttai MONTH DAY YEAR SUB SiON DATE 06) 7 vEs of v.i. co noi.i. EXPECTED sveM:ssioN DATE) 7 No l l l Aesr A Act n.,mn io i.x .nac... i . ano,..,mai.iv tm..n .,nwo-..ac. tro.wrm.n nn.si 06, At 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on April 6,1990 while shutdown in hiode 3. Hot Standby, 557 degrees Fahrenheit and 22$0 psia, a review of the Steam Generator Blowdown monitor high radiation alarm setpoint revealed that the setpoint was non-conservative due to administrative deficiency. The non-conservative setpoint was entered when the monitor was first placed in service on Niarch 13, 1990. The monitor was declared out of  ;

service and the appropriate Limiting Condition for Operation (LCO) was entered. By 1710 the correct setpoint was installed, the monitor was returned to service, and the LCO was exited. An administrative deficiency allowed different setpoints to appear in two separate documents. During the time the incorrect ,

setpoint was u<ied, activity in the steam generators was less than hiinimum Detectable Activity, so radioactive discharges to the environment did not occur via this path. The High Radiation Alert setpoint .

would have alerted operators to increasing Steam Generator Blowdown acticity before the correct alarm value was exceeded. All other liquid and gaseous effluent monitor high radiation alarm setpoints were reviewed and found to be correct. The referer ce containing the non-conservative setpoint will be revised by August 31, 1940.

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1. Descrintion of Event At 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on April 6,1990, while shutdown in Mode 3, Hot Standby, 557 degrees Fahrenheit and 2250 psia, a review of radiation monitor setpoints revealed that the Steam Generator Blowdown monitor high radiation alarm setpoint was non-conservative due to administrative deficiency. The Steam Generator Blowdown monitor setpoint depends on the amount of dilution from circulating  ;

and service water systems. The Steam Generator Blowdowr, monitor setpoint was reviewed in i

, reparation to reduce the number of running circulating water pumps to two, to facilitate raintenance on components in the intake structure. During the review, it was discovered that the

.etpoint in the monitor was not conservative. Other equipment and systems were not affected.

The Shift Supervisor immediately declared the monitor out of service and entered the appropriate ,

Limiting Condition for Operation (LCO). By 1710, the correct setpoint was installed, the monitor '

was returned to service, and the LCO was exited.

it. Cause of Event

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Root cause of the event was administrative deficiency in that two conflicting high radiation alarm j setpoints were provided by different references. The Steam Generator Blowdown high radiation i alarm setpoint is contained in the Radiological Effluent Monitoring and Offsite Dose Calculation  !

Manual (REMODCM). Plant Technical Specifications refer to the REMODCM for liquid and  !

gaseous effluent monitor setpoints. A non-conservative setpoint was contained in the Radiation 1 Monitoring Manual, which provides general information on the radiation monitoring system,  !

calculations of expected radiological constituents in plant process streams, and expected area  !

radiation levels. Setpoints in the Radiation Monitor Manual are used when the REMODCM or l Plant Technical Specifications do not stipulate a setpoint. When the monitor was placed in service 1 on March 13, 1990, the setpoint from the Radiation Monitor Manual, vice the REMODCM, was '

erroneously used.

f III, Anah'sii of Event l This event is reportable under 10CFR50.73(a)(2)(1), as an operation nr condition prohibited by Plant Technical Specifications. The Steam Generator Blowdown radiation monitor was first placed I in service on March 13, 1990, using the non-conservative setpoint. Prior to March 13,1990, steam  ;

generator blowdown was sampled every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in accordance with the associated LCO of Plant .

Techmcal Specifications. Throughout the period from March 13,1990 to April 6,1990, the activity q

. in the steam generators was less than the Minimum Detectable Activity (MDA). Therefore f radioactive discharges to the environment did not occur from Steam Generator Blowdown. Steam j Generator Blowdown is automatically isolated when the high radiation alarm setpoint is exceeded. ,

The setpoint used in the radiation monitor was 4.9 E -5 uCi/ml. The setpoint stipulated in the j REMODCM is 1.6 E -5 uCi/ml. While the setpoint used was three times the REMODCM setpoint, '

the High Radiation Alert setpoint of 3.00 E -6 uCi/ml would have alerted operators to increasing Steam Generator Blowdown activity before the REMODCM value was exceeded.

IV. Coir _ective Action  !

The setpoint in the Steam Generator Blowdown radiation monitor was changed to a conservative i value by 1710, on April 6,1990. All other liquid and gaseous effluent monitor high radiation  ;

alarm setpoints were reviewed and found to comply with, or be conservative with respect to, the [

.etpoints in the REMODCM. The Steam Generator Blowdown monitor setpoint was 'he only one l which was non-conservative with respect to the REMODCM. Appropriate sections of the Radiation j Monitor Manual will be revised by August 31, 1990 to clearly identify the setpoints for hquid and gaseous effluent monitors which are contained in the REMODCM. Also, internal procedures which record setpoints currently in use in radiation monitors will be revised to include notation, where applicable, that the REMODCM contains the setpoints to be used.

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\'. Additionni Information Three other Licensee Event Reports (LERs) were submitted on incorrect setpoints caused by deficient administrative control over setpoints from reference documents. LER 86-017-00 reported an incorrect Overtemperature Deha Temperature Ki constant due to failure to upda'.e procedures to the latest revision of Plant Technical Specifications. LER 86-053-00 reported incorrect intermediate Range Rod Stop and High Flux Reactor Trip Setpoints due to conflicting information in the Westinghouse Startup h1anual and Precautions, Limitations and Setpoints document.

Corrective actions for LER's 86-047-00 and 86-053-00 reviewed Reactor Trip and Engineered Safety Features setpoints, and revised appropriate procedures, which did not include the Radiation Monitoring system. LER SS-018-00 reported that on two occasions the Control Building Inlet Ventilation monitor contained a non-conservative high radiation alarm setpoint. Defauh setpoints established by the manufacturer to perform factory tests had not been revised to plant-specific values. Corrective actions for LER 88-018-00 included review of monitor setpoints and revision of default setpoints to plant-specific values. The Steam Generator Blowdown monitor was exempted from these corrective actions because it was not in service or near the anticipated in service date.

This setpoint error was missed during the 1988 review of Technical Specifications and Surveillance Procedures because the engineer performing the review incorrectly assumed inat the Radiation Alonitor Manual and the REMODCM were the same manual. Surveillance procedures reviewed by this engineer which involved the REMODCM were reviewed a second time. Additional problems were not revealed.

Ells Codes Sutems IL - Radiation Monitoring System comnonents MON - monitor NRC Form 366A (6-80)