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Provides Description of Abnormal Releases Re Rev to Semiannual Radioactive Effluent Release Rept for Jul-Dec 1988.On 880211,0.35 Ci Liquid Release Involved Unmonitored Release from Waste Monitor Tank B to Environ
	ML20244C894
Person / Time
Site:	Catawba
Issue date:	04/05/1989
From:	Tucker H; DUKE POWER CO.
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
	NUDOCS 8904210034
	Download: ML20244C894 (2)
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p DUKE POWER COMPANY :

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CHARLOTTE, N.O. 28242 HALH.TUCKEH TELEPHONE vsor emessenant (7o4) 073-4531

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April 5, 1989

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Document Control Desk

' U. S. Nuclear Regulatory Cnanission Washington,-D.:C. 20555 Subj ect: Catawba Nuclear Station, Units.1 and 2 Docket Nos. 50-413 and'50-414 Revision to Semi-Annual ~ Radioactive Effluent Release Report Gentlemen:

My March 1, 1989 letter to the NRC Document Control Desk transmitted the Catawba Semi-Annual Radioactive Effluent Release Report for the period.from July 1988 to December 1988.~ The report identified an abnormal 0.35 Curies liquid release and an abnormal 7.46 Curies gaseous release. However, no other description of the two abnormal releases was provided.

The 0.35 Curies liquid release involved an unmonitored release from Waste l

Monitor Tank (WMT) B to the' environment on February 11, 1988. The Process

(

Radiation Monitor was isolated at the time of the event.due to improper verification of the monftor's operability status. The tank had been sampled i

before the discharge and was.within administrative limits for release. When the tank was near the 507. level, the alignment error was discovered and-the-release was immediately terminated. This event was reported to the NRC as Licensee Event Report No. 413/88-10 which was-transmitted to the Document Control Desk per my letter dated March 11, 1988 (see' attachment).

The 7.46 Curies gaseous release involved an inadvertent release from the in-service Waste Gas Decay Tank to the environment due to a leak following maintenance activities. The concentration of the radioactive gases released was insufficient to cause an alarm of the Auxiliary Building Ventilation or Unit Vent Radiation monitors. Station personnel were not aware of the leak until the Waste Gas Decay Tank was empty. This event was reported to the NRC as voluntary Licensee Event Report No. -413/88-12 which was transmitted to the Document Control Desk per my letter dated March 31, 1988 (see attachment).

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,Very truly:yours,.

b-H.

B.- Tucker

- Attaciunent JGT/2/SRRL r.

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Mr. S. D. Ebneter n

' Regional' Administrator, Region,II.

U. S.' Nuclear Regulatory Commission

'101 Marietta st., NW,_ Suite 2900' Atlanta,'GA:30323' Mr.-W.:T ' Orders h7C Resident Inspector Catawba Nuclear Station

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ancism DuxE POWER GOMPANY P.O. BOX 33189 CHARLOTTE. N.C. 28949 RAL B. TUCEER retze,cowe (7o4) 073-4 &31 vics enseenwr wuctsaa pococcTion March.31, 1988 Document Control Desk

.U. S. Nuclear Regulatory Commission Washington, D. C.

20555 Subj ect:

Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 LER 413/88-12 Gentlemen:

Pursuant to 10 CFR 50.73 Section (a) (1) and (d), attached is Licensee Event Report 413/88-12 concerning an inadvertent release from the in-service radioactive waste gas decay tank due to leakage following system maintenance. This event was considered to be of no~ significance with respect to the health and safety.of the.

.public.

Very_truly yours, I

RKWTW Hal B. Tucker

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I JGT/10015/sbn Attachment xc:

Dr. J. Nelson Grace American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library U. S. Nuclear Regulatory Commission The Exchange, Suite 245 101 Marietta Street, NW, Suite 2900 270 Farmington Avenue Atlanta, Georgia 30323 Farmington, CT 06032 M&M Nuclear Consultants Mr. P. K. Van Doorn l

1221 Avenue of the Americas

.NRC Resident Inspector New York, New York 10020 Catawba Nuclear Station INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Lt.Ah j

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- ( U'.. S : N'uclser Rigulstory Commission

b. 1-LMarch 31, 1988.

'Page Two'

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P.~M. Abraham B. W.'Bline D. G. Browne L. T. Burba K. S.:Canady A. V. Carr R. M. Dulin R. C. Futrell W. A. Haller?

G. W. Hallman J. W. Hampton C. L. Harlin 'ONS C. L. Hartzell S. S. Kilborn' }{;

E.-Laccasse CNS P. G. LeRoy-J. J. Maher Corp. Comm.-

M. D. McIntosh-T.-E. Mooney.

R. W. Quellette N. A. Rutherford L. E. Schmid R._0. Sharpe.-

P.'L. Stiles J. E. Thomas R. L. Weber

'R. L. White

'J. W. Willis Manager, QA Technical Services, EC-1258 QA Technical Services NRC Coordinator, EC-1255 David Sisk (PG&E)

NC MPA-1

-NCEMC PMPA SREC~

Group File: CN-801.01

-Group File: CN-815.04

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.-,v o ei On February 8, 1988, from approximately 0530 hours0.00613 days 0.147 hours 8.763227e-4 weeks 2.01665e-4 months to approximately 0730 hours0.00845 days 0.203 hours 0.00121 weeks 2.77765e-4 months , the contents of the in-service Waste Gas Decay Tank (WGDT) were inadvertently released to the environment due to a leak following a maintenance activity. The concentration of the radioactive gases released was insufficient to cause an alarm of the Auxiliary Building Ventilation or Unit Vent Radiation Monitors.

Station personnel were not aware of the leak until the WGDT was empty. An estimated 7.46 Curies of noble gases were released during the event. Unit I was at 97% power and Unit 2 was in Mode 6 Refueling, at the time of this incident.

The leakage was subsequently discovered to have occurred at a removabla vent plug I

on a Waste Gas (WG) compressor moisture separator.

Both Radwaste Chemistry (RDW) and Mechanical Maintenance (MM) personnel had attempted to remove the vent plug prior to the maintenance, but it could not be removed and did not appear to have moved. Apparently, the vent plug had been moved just enough to unseat it and caused it to leak. This incident is also attributed to a personnel error. A RDW Specialist incorrectly calculated an increase in the in-service WGDT pressure during the shift.

This incident has been reviewed with the RDW Specialist involved. A change to the RDW procedure has been initiated to require leak checks to be performed. A program change request is being submitted for the Operator Aid Computer to provide an alarm upon decreasing WGDT pressure. This event was determined to be not reportable. This LER is being submitted as a voluntary report for information purposes. The health and safety of the public were unaffected by this event.

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,-nac % ms4,nm BACKGROUND:

The purpose of the Waste Gas (WG) System is to remove fission product gases from radioactive fluids. WG Decay Tanks (EIIS:TK) are provided to contain these gases for a relatively long period of time. The system is designed to allow for maximum decay time of radioactive gases prior to their monitored and controlled-l release to the environment.

The WG System is a closed loop system comprised of two compressors (EIIS: CMP),

two catalytic hydrogen recombiners (EIIS:RCB), six WG decay tanks (WGDTs) for normal power service and two WGDTs for service at shutdown and startup. The system is shared between the two Catawba Units.. All of the WG system equipment is located in the Auxiliary Building. The eight WGDTs are vertical and cylindrical with a volume of 600 cubic feet each and a design pressure of 150 psig.

During normal power operation, nitrogen gas, with contained fission gases, is continuously circulated around the WG system loop by one of two compressors.

Fresh hydrogen gas is continuously introduced into both Unit Volume Control Tanks (VCTs), where it is mixed with fission gases which have been stripped from the Reactor (EIIS:RCT) Coolant (EIIS:AB) into the VCT gas space by the VCT letdown line nozzle (EIIS:NZ'L) spray. The hydrogen and fission gas mixture is continuously vented from the VCT into the circulating nitrogen and fission gas stream in the WG loop.

The resulting mixture of nitrogen, hydrogen, and fission gases is transferred by one of the compressors to one of the catalytic hydrogen recombiners where enough oxygen is added to reduce the hydrogen to a residual level. After the resulting water vapor is condensed and removed, the cooled gas stream is discharged from the recombiner, routed to a WGDT, and sent back to the compressor suction to complete the loop circuit. During this process the in-service WGDT's pressure and radioactivity level gradually increase. When these parameters approach established limits, another WGDT is placed in service and the previously used WGDT is isolated.

This tends to equalize the radioactivity of the WGDTs and minimizes the off-site dose consequences of a WGDT rupture or leak.

The primary source of radioactive gas input to the WG System is the VCT purge.

Smaller quantities are received from the recycle evaporator Eas strippers, the NC Drain Tanks (NCDTs) and the Recycle Holdup Tanks (RHTs).

The WG compressors are water sealed, centrifugal displacement compressors. Gas enters the compressor suction at a pressure of 0.5 psig and at a temperature of 130 deg. F or lower. After compression, the gas is discharged along with the seal water into the moisture separator (where the seal water is removed), and the gas is then discharged to the recombiner. The seal water is returned to the j

l compressor after being cooled and passed through a Y-strainer. An adjustable back pressure control valve maintains the normal moisture separator pressure at 50 to 60 psig to provide the motive force for compressor seal water circulation.

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The Auxiliary Building Ventilation (VA) System is designed to provide the normal ventilation / heating and emergency exhaust requirements for the Auxiliary Building. Control of airborne radioactivity in the Auxiliary Building is accomplished by exhausting air supplied to clean areas through potentiall'/

contaminated areas, through the filtered exhaust ducts. This provides a positive flow of air from areas not expected to be contaminated to areas of potential contamination. The filtered exhaust normally bypasses the installed high efficiency particulate absolute (REPA) (EIIS:FLT) filters and charcoal adsorber banks, and is routed directly to the Unit vents.

Process Radiation Monitor (EMF) 1 EMF 41 monitors the gaseous airborne radioactivity levels of the Auxiliary Building air by sequentially sampling 1 cubic foot per minute of air taken from 12 pre-selected points in the VA filtered exhaust ducting. When the monitor detects the gaseous radioactivity levels ~

corresponding to a 2 mR/hr submersion dose rate in a Xenon-133 cloud (Trip 2 setpoint), the filtered exhaust is automatically switched to the FILTER MODE and

-an audible alarm is received in the Control Room. A visual alarm (Trip 1) occurs at 75% of the Trip 2 setpoint.

The Fuel Pool Ventilation (VF) Systems, Containment Purge (VP) Systems, VA Systems, Containment Air Release and Addition (VQ) Systems, Annulus Ventilation (VE) Systems, conden' sate steam air ejectors, WGDT releases, and other potentially radioactive sources are exhausted to the Unit vents. Unit 1&2 EMF 35, 36, and 37 are designed to continuously monitor the particulate, gaseous and iodine radioactivity levels of the air being exhausted through the Unit vents to the atmosphere.

'Upon detection of high radioactivity levels by the Unit vent radioactivity monitors, the affected Unit's VF, VP, VA and VQ System fans will automatically be secured and an alarm will sound in the Control Room. Additionally, any open VP, WG, or VQ release isolation valves will automatically close in an attempt to isolate the probable sources of the high radioactivity. The Unit vent gaseous radioactivity monitor's (1&2 EMF 36) alarm / trip setpoints are established and set to limit the annual Site Boundary whole body dose to any member of the public from gaseous radioactivity, to 0.5 Rem.

Technical Specification 3.11.2.6 limits the quantity of radioactivity contained in any WGDT to 97,000 Curies of noble gases (considered as Xenon-133 equivalent).

This limit is based upon assuring that whole body exposure to a member of the' public at the nearest Exclusion Area Boundary (EAB) will not exceed 0.5 Ram following an uncontrolled release of the tank's coutents.

In-service WGDTs are sampled and isotopically analyzed daily to determine the Curie content.

1 DESCRIPTION OF INCIDENT:

On January 13,1988, at 1230 hours0.0142 days 0.342 hours 0.00203 weeks 4.68015e-4 months , Radwaste Chemistry (RDW) originated Work The Request 554 RDW to allow cleaning the Y-strainer on WG Compressor B.

compressor had recently been rebuilt and yet low flow alarms were being received on the hydrogen recombiner when this compressor was in service.

It was suspected that the compressor was not receiving adequate seal water due to its Y-strainer f

being obstructed.

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,w=ac wmarenm On February 5, 1988, at 1315 hours0.0152 days 0.365 hours 0.00217 weeks 5.003575e-4 months , a Chemistry Supervisor originated Tagout (R&R).18-48 to allow draining the WG Compressor B moisture separator prior to l

beginning Y-strainer cleaning.

The draining would eliminate spilling of seal

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water when the Y-strainer was opened. The R&R directed the RDW personnel to open

.the moisture separator drain valves to the sump (after securing and isolating the compressor) and after the moisture separator level stopped decreasing, to remove j

the vent plug on the side which would allow air to enter and all the water to j

drain out.

The R&R said to allow approximately 10 minutes before reinstalling l

the vent plug and clearing the R&R.

At 1345 hours0.0156 days 0.374 hours 0.00222 weeks 5.117725e-4 months , the Chemistry Supervisor originated R&R 18-49 to allow cleaning of the Y-strainer. The R&R specified the proper equipment alignments to be made folicwing completion of tha work and stated that the vent plug was to be checked l

for leakage upon return;.;s the compressor to service.

On February 7,1988, at 1338 hours0.0155 days 0.372 hours 0.00221 weeks 5.09109e-4 months , a Health Physics (HP) Technician obtained the daily in-service WGDT gas sample from WGDT D and submitted the sample for isotopic analysis. The analysis showed the WGDT contained 6.3482 Curies (Xenon 133 equivalent) of noble gases.

At approximately 2300 hours0.0266 days 0.639 hours 0.0038 weeks 8.7515e-4 months , on February 7, 1988, a RDW Specialist initiated R&R 18-48 which included securing, draining, and isolating WG Compressor B.

When the moisture separator level stabilized, the RDW Specialist attempted to recove the vent plug to completely drain the water from the separator. The vent plug would not move. The Mechanical Maintenance (MM) crew then attempted to remove the vent plug, but also were not successful. No one was aware that the vent plug had turned.

At 2330 hours0.027 days 0.647 hours 0.00385 weeks 8.86565e-4 months , the RDW and MM Supervisors agreed that the work could continue since the moisture separator level indicated zero. At 2350 hours0.0272 days 0.653 hours 0.00389 weeks 8.94175e-4 months , R&R 18-48 was cleared by the RDW personnel.

On February 8, 1988, at 0030 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months , R&R 18-49 was initiated by RDW personnel to allow MM to clean the Y-strainer. At approximately 0300 hours0.00347 days 0.0833 hours 4.960317e-4 weeks 1.1415e-4 months , MM personnel removed, cleaned, and replaced the strainer.

1 At 0400 hours0.00463 days 0.111 hours 6.613757e-4 weeks 1.522e-4 months , the RDW Specialist recorded the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months WGDT pressures. WGDT D pressure was recorded as 42.8 psig.

The WGDT pressures are printed hourly by the Operator Aid Computer (OAC). The RDW personnel record these pressures only every 4

4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months in the RDW logbook (i.e., only the 0400, 0800, 1200... pressures are f

recorded). At 0500 hours0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months , WGDT D pressure was 42.4 psig according to the OAC printout.

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At 0530 hours0.00613 days 0.147 hours 8.763227e-4 weeks 2.01665e-4 months , the RDW Specialist cleared RER 18-49 and started WG Compressor B.

l The RDW Specialist and a MM Technician performed a leak check of the Y-strainer and no leaks were found. The leak check was performed by spraying a liquid

'(SNOOP) on the sealing surfaces and observing for bubbles. The vent plug was not checked since it had not been removed and no one believed it had been moved by the attempts to remove it.

The noise level from the running compressor would have made it difficult to hear any leakage.

At 0600 hours0.00694 days 0.167 hours 9.920635e-4 weeks 2.283e-4 months , WGDT D pressure was 30.1 psig according to the OAC printout (a 12.3 psig decrease since 0500 hours0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months ).

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.At 0615 hours0.00712 days 0.171 hours 0.00102 weeks 2.340075e-4 months , the RDW Specialist signed off the work request as completed.

Low flow and high oxygen alarms on the hydrogen recombiner began to occur intermittently. The RDW Specialist reverified the WG valve alignments. The RDW Technician informed the RDW Specialist that he was having trouble establishing eduction of the RHTs. They verified the valve alignments were correct. Since it was nearly shift turnover time, the RDW Specialist began making preparations for turnover. When calculating the in-service WGDT pressure change for the shif t, the RDW Specialist mistakenly utilized the 0500 hour0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months , 42.4 psig OAC reading instead of the 0600 hour0.00694 days 0.167 hours 9.920635e-4 weeks 2.283e-4 months , 30.1 psig OAC reading and documented a 1.3 psig WGDT pressure increase during the shift.

During turnover to the on-coming RDW shift personnel, the RDW Specialist discussed the problems with the high oxygen alarms and RHT eduction. The RDW Specialist speculated that the oxygen analyzer may have been going out of calibration. Shift turnover was completed at approximately 0655 hours0.00758 days 0.182 hours 0.00108 weeks 2.492275e-4 months .

At 0700 hours0.0081 days 0.194 hours 0.00116 weeks 2.6635e-4 months . WGDT D pressure was 14.7 psig according to the OAC.

At 0710 hours0.00822 days 0.197 hours 0.00117 weeks 2.70155e-4 months . WG Compressor B automatically tripped on low suction pressure.

By 0720 hours0.00833 days 0.2 hours 0.00119 weeks 2.7396e-4 months , RDW personnel had verified the valve alignment from R&R 18-49 in an attempt to discover the cause of the compressor trip. The valve alignment was correct. At 0735 hours0.00851 days 0.204 hours 0.00122 weeks 2.796675e-4 months , the cause was discovered to be the loss of all pressure in WGDT D.

The RDW ' personnel contacted and informed their General Supervisor of the situation.

At 0745 hours0.00862 days 0.207 hours 0.00123 weeks 2.834725e-4 months , RDW personnel notified HP and Operations (OPS) personnel of the loss of all pressure in WGDT D.

At the same time, an HP Scientist and HP l

Technician in the Control Room observed that the 1 EMF 41 chart recorder was sho' ing approximately 1000 counts per minute (cpm) for sample points 11 and 12 at approximately 0715 hours0.00828 days 0.199 hours 0.00118 weeks 2.720575e-4 months . The Trip 2 setpoint was set at 4000 cpm and the Trip 1 setpoint'was 3000 cpm.

They informed the Control Roor Operators (CRos) of their

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findings.

At 0750 hours0.00868 days 0.208 hours 0.00124 weeks 2.85375e-4 months , RDW personnel entered the WG compressor room and checked the manual drain valves. The valves were found to be closed.

In the room, they i

discovered a small amount of water on the floor directly beneath the moisture separator vent plug. The plug was only hand tight.

At 0800 hours0.00926 days 0.222 hours 0.00132 weeks 3.044e-4 months , WGDT D pressure was 0 psig according to the OAC.

At 0810 hours0.00938 days 0.225 hours 0.00134 weeks 3.08205e-4 months , HP and OPS personnel in the Control Room removed the 1 EMF 41 chart recorder paper. Review of the chart showed that all 12 sample point readings began to increase at approximately 0530 hours0.00613 days 0.147 hours 8.763227e-4 weeks 2.01665e-4 months , with points 11 and 12 being consistently highest. Normal background readings for the EMF are less than 100 cpm. However, between 0530 and 0730 hours0.00845 days 0.203 hours 0.00121 weeks 2.77765e-4 months , points 1 through 10 had increased to between 200 and 800 cpm.

Point 11 reached 2100 cpm and point 12 reached 1500 cpm. All readings increased abruptly at approximately 0530 hours0.00613 days 0.147 hours 8.763227e-4 weeks 2.01665e-4 months , and remained relatively constant until approximately 0715 hours0.00828 days 0.199 hours 0.00118 weeks 2.720575e-4 months , when all 12 readings began trending downward. All 12 readings had returned to normal by 0730 hours0.00845 days 0.203 hours 0.00121 weeks 2.77765e-4 months .

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wew manim At 0815 hours0.00943 days 0.226 hours 0.00135 weeks 3.101075e-4 months , RDW personnel isolated WGDT D.

At 0840 hours0.00972 days 0.233 hours 0.00139 weeks 3.1962e-4 months , RDW personnel filled WGDT D with nitrogen gas to 45 psig for functional testing and to allow for leak identification. At 0945 hours0.0109 days 0.263 hours 0.00156 weeks 3.595725e-4 months , WGDT D was unisolated.

HP personnel then collected an air sample and performed a radiation survey in the WG compressor room.

At 1018 hours0.0118 days 0.283 hours 0.00168 weeks 3.87349e-4 months , RDW personnel entered the room and leak checked the vent plug.

The plug was leaking and could not be tightened enough to stop the leakage. The compressor was then secured and isolated. At 1050 hours0.0122 days 0.292 hours 0.00174 weeks 3.99525e-4 months , RDW personnel placed WG Compressor A in service. Work Request 564 RDW was originated to repair the leaking vent plug.

At 1135 hours0.0131 days 0.315 hours 0.00188 weeks 4.318675e-4 months , HP personnel generated Gaseous Waste Release (GWR) package 57 to 1

document the inadvertent release of the contents of WGDT D.

The sample obtained on February 7, 1988, at 1338 hours0.0155 days 0.372 hours 0.00221 weeks 5.09109e-4 months , and the February 8, 1988, 0500 hour0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months , tank l

pressure were used to calculate the total amount of radioactivity released (7.46 l

Curies of noble gases). The whole body dose at the Site Boundary due to this release was calculated to be less than 0.00004 Rem. At 1140 hours0.0132 days 0.317 hours 0.00188 weeks 4.3377e-4 months , the Operations Shift Supervisor was informed that the Site Boundary whole body dose limit had not been exceeded.

l On February 18, 1988, MM personnel removed the old vent plug, cleaned the plug hole threads, applied sealant to a new vent plug and installed it.

The new plug leaked during the functional verification. On February 19, 1988, MM personnel removed the vent plug, cleaned the threads, reapplied sealant and installed the plug. On February 20, 1988, RDW personnel functionally verified that the vent plug did not leak and the compressor was returned to service.

)

_ CONCLUSION:

The release of the contents cf WGDT D occurred due to the leaking vent plug on the WG compressor's moisture separator.

The attempts by RDW and MM personnel to remove the vent plug apparently moved the plug sufficiently to unseat it and cause the leak. None of the personnel involved believed that the vent plug had moved and therefore, they did not check it for leaks upon returning the compressor to service. Although this incident would have been prevented if the leak check had been performed by the involved personnel, there were no procedure violations or obvious personnel errors identified.

Additionally, the procedure for the WG System was not determined to be inadequate.

l This incident is also attributed to a personnel error. The RDW Specialist incorrectly calculated a pressure increase in the WGDT during the shift while preparing for turnover.

This occurred because the 0500 hour0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months pressure was used instead of the 0600 hour0.00694 days 0.167 hours 9.920635e-4 weeks 2.283e-4 months pressure.

If the correct pressure reading had been used for the calculation, the leak would have become apparent and could have been terminated before all the radioactive gas was released. The calculation was performed at approximately 0645 hours0.00747 days 0.179 hours 0.00107 weeks 2.454225e-4 months , and the majority of the gaseous radioactivity had escaped by that time.

1 This incident has been discussed with the RDW Specialist involved. Additionally, the importance of attention to system status and trends, and ensuring accuracy of

^i J 5 %Cosas 4844af;mv ::vwua MIC 8w e Je6A LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 4=c.n :ve so rue in* ets i y n F ACsLITY maast it, OOCK ET NuesSS A (21 gga gygggR St P AGE Ji "t*Z."

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't'a Catawba Nuclear Station, Unit 1 015 l 010 l 0 l4 l 113 8l8 Ol'1 l 2 -0l0 ol7 0F rj 9 rta w a.c.,,

a,<.,,, m,w ~ac w anna o <m information submitted has been stressed to all Chemistry personnel through staff-meetings.

RDW Technicians are now required to log WGDT pressures hourly instead of every four hours to increase the probability of detecting a leak. The RDW procedure for returning the WG System to service following maintenance is being enhanced to require leak checks even if an attempted system breach appears to have been unsuccessful.

The Chemistry Section has recommended that a program change request be submitted to have the OAC provide an alarm upon decreasing pressure in the WGDTs. This alarm should provide rapid notification of WGDT leakage and appears to be the best solution to prevent this type of incident from recurring.

A Station Problem Report (SPR) had been previously originated which recommended that the vent plugs be replaced with isolation valves. This SPR was placed on the inactive list to permit completion of modifications of higher priority.

Station Management is currently evaluating the need to activate the SPR.

There has been one previous incident at Catawba involving an inadvertent release from a WGDT (see LER 413/87-01) The corrective actions taken as a result of the previous incident could not have prevented this event. This is considered to be a recurring event.

CORRECTIVE ACTION:

SUBSEQUENT (1) The leak was identified, isolated and repaired.

(2) The incident was discussed with the individual involved.

(3) All Chemistry personnel were reminded of the importance of attention to system status and trends and the submittal of accurate information.

(4) A change to the RDW WG System maintenance procedure was initiated to 4

require performance of leak checks even if a WG System breach appeared to be unsuccessful.

(5) RDW personnel are now required to log WGDT pressures every hour.

(6) Chemistry recommended that a program change request be submitted to I

have the OAC provide an alarm upon decreasing pressure in the WGDTs.

l l

PLANNED (1) The need for activating the SPR to add a valve instead of the plug on the moisture separator will be reviewed.

l N3C SQ AM 366A

1 vs wcuam aic a. o.. m v u i a c e 2.u LICENSEE EVENT REPORT (LER) TEXT CONTINUATION u,.c.e 3.se r m a 8.e.a gg g p n P..Citif y Namt m DOCati Nuussa (21 kgm NUMeta +si sact 1

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,-c r asu,nm (2) A completed OAC program change request will be submitted to add computer points necessary to obtain an OAC alarm on decreasing WGDT pressure.

SAFETY ANALYSIS:

The leakage of the entire contents of WGDT D resulted in the release to the environment of an estimated 7.46 Curies of noble gases. A radioactive gas leak of this type is bounded by Catawba's Final Safety Analysis Report (FSAR), Section 15.7.1, Radioactive Waste Gas Decay Tank Leak or Failure. The maximum radioactivity level in a single WGDT is limited to 97,000 Curies by Technical Specification 3.11.2.6.

This limit assures that in the event of an uncontrolled I

release of the tank's contents, the resulting whole body exposure to an individual at the EAB will not exceed 0.5 Rem.

The EAB whole body exposure i

resulting from this release is calculated to be less that 0.00004 Rem.

l J

The release to the environment was continuously monitored by 1&2 EMF 36, and no high radiation alarms were generated during the release. Additionally, 1 EMF 41 detected the increased gaseous radioactivity levels in the area of the leak.

However, the concentration of radioactive gases was below the alarm and trip setpoints of the EMF.

The highest 1EMP41 reading was approximately 2100 cpm, with the Trip 1 setpoint of 3000 cpm and Trip 2 setpoint of 4000 cpm.

Throughout the incident there were no cases of personnel contaminations, and no abnormally high exposures to radiation occurred. The release of the estimated 7.46 Curies of radioactive noble gases into the WG compressor room consisted of 2233.5 standard cubic feet of gas released over a 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months period (approximately 18.7 standard cubic feet per minute (SCFM) average). The designed VA exhaust from the compressor room is 1300 SCFM. Therefore, the gases released into the room were immediately diluted by the large amount of clean air make-up into the room. The exhaust duct inlet is approximately 10 feet directly above the leaking i

vent plug and creates a sweeping current of air through the room's wall penetrations, across the compressor package, and up to the duct where it is i

exhausted. A smoke test of the room later verified this. This may explain why the HP Technician present for the leak check at 0530 hours0.00613 days 0.147 hours 8.763227e-4 weeks 2.01665e-4 months did not detect abnormally high Beta and Gamma radiation levels in the. room.

If workers in the room had been exposed to significant concentrations of noble gases, they would have found themselves to be contaminated with short, lived particulate daughters when frisking after exiting the room. The room is a contaminated area which requires the use of protective clothing for entry and whole body frisking upon exiting.

If the WGDT had contained approximately twice the amount of radioactivity (15 Curies or more), Control Room personnel would have received a Trip 1 and 2 alarm on IEMF41 and VA would have automatically switched to the FILTER MODE. This would have prompted an immediate search by Station personnel (including RDW and HP) of the area indicating the highest activity on 1 EMF 41.

It is probable that RDW personnel would have closely examined the WG System parameters, noticed the decreasing WGDT pressure, and isolated the compressor that had just been returned

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,w uc w w.,on to service. Thus, a majority of the WGDT's contents would likely not have been released to the environment.

This event was determined not to be reportable. This LER is being submitted as a voluntary report for information purposes.

~

The health and safety of the public and Station personnel were not affected by this incident.

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C# 9/5 07 Dtrxz POWER GOMPANY P.O. BOX 33189 CHARLOTIT. N.C. 28949 HAL B. TUCKER rug.mynows

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March 11, 1988 4

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

20555 L'

Subj ect:

Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 LER 413/88-10 Gentlemen:

1 Pursuant to 10 CFR 50.73 Section (a) (1) and (d), attached is Licensee Event Report 413/88-10 concerning an unmonitored release of liquid radweste due to personnel errors. This event was considered to be of no significance with respect to the health and safety'of the public.

l Very truly yours, j

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Hal B. Tucker JGT/10001/sbn i

l Attachment

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Dr. J. Nelson Grace American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library U. S. Nuclear Regulatory Commission The Exchange, Suite 245 101 Marietta Street, NW, Suite 2900 270 Farmington Avenue Atlanta, Georgia 30323 Farmington, CT 06032

)

M&M Nuclear Consultants Mr. P. K. Van Doorn 1221 Avenue of the Americas NRC Resident Inspector New York, New York 10020 Catawba Nuclear Station INPO Records Center Suite 1500.

1100 Circle 75 Parkway Atlanta, Georgia 30339

Fr 17r.

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,;U. S.! Nuclear R:guintery Commiccion March 11', 1988

_Page Two

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P. M.' Abraham

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.D G. Browne L. T. Burba K. S. Canady A. V.-Carr.

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M. D. McIntosh T, E. Mooney R. W. Quellette N. A. Rutherford L. E. Schmid R. O. Sharpe P. L. Stiles J. E. Thomas,

R. L. Weber R. L. White J. W.~Willis Manager, QA Technical Services, EC-1258 QA Technical Services NRC Coordinator, EC-1255 David Sisk.(PG&E)

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-. = m m om On February 11, 1988, at '2055 hours0.0238 days 0.571 hours 0.0034 weeks 7.819275e-4 months , an unmonitored release of Waste Monitor Tank (WMT) B to the environment occurred. The Process Radiation Monitor (EMF) for the release flow path was isolated at the time due to improper verification of the monitor's operability status. The tank had been sampled before the discharge and was within administrative limits for release. When the tank was near the 50%

level, the alignment error was discovered and the release was innediately terminated. The proper notifications were made and further sampling was conducted. The sample results determined that no administrative limits for the discharge were exceeded. Unit 1 was in Mode 1, Power Operation, and Unit 2 was in Mode 5, Cold Shutdown, during this incident.

This incident has been attributed to a personnel error. The Assistant Nuclear Chemistry Technician whc performed the valve alignment did not adequately review the information in the Liquid Waste Release package before he started the release, and assumed the EMF was not operable. Additionally, the Lead person allowed a Technician in training to independently verify the final release valve alignment which was not in accordance with the Supervisor's instructions. The incident has been discussed with the involved personnel with emphasis on attention to detail and the proper use of independent verification. No administrative limits were exceeded. The health and safety of the public were unaffected by this event.

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BACKGROUND:

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Potentially radioactive liquid wastes from sumps, samples, laundry, showers and drains in the Auxiliary Building are routed to the Floor Drain Tcnk (EIIS:TK) via filters (EIIS:FLT) and separation tanks. Liquid waste from the Floor Drain Tank is further processed through strainers (EIIS:STR), damineralizers (EIIS:FDM), and filters and routed to either Waste Monitor Tank (WMT) A or B.

When approaching full capacity, these tanks are isolated and sampled to determine radioactivity and chemical content.

If the tank contents meet previously established guidelines, the tank is pumped at the proper flow rate for dilution into the Low Pressure Service Water System for release into the lake.

A portion of the flow from this tank is routed through Process Radiation Monitor (EIIS: MON) 1 EMF-49 during the discharge.

1 EMF-49 is a dual range process radiation monitor designed to detect and count gasma radiation.

It is interlocked to terminate flow in the liquid wasta release process line if a radioactivity level higher than the pre-established trip setpoint is detected.

The trip setpoint is established based on the radioactivity levels detected in the isotopic analysis of the samples.

1WL-124, Liquid Waste Release Isolation Valve (EIIS:V), is automatically closed in this event, stopping the release.

1WL-124 may also be closed manually from the Control Room.

If 1 EMF 49 is not operable, a release of liquid waste is still possible by perftunng a second sample analysis and. comparing it with the first.

If the samp 6 ' total activities do not agree within 20%, a third sample is to be taken.

From ;he three samples, the highest activity values of each identified isotope is chosen. These values are summed for a maximum total activity.

These values are also compared individually to each specific isotope's limits for release.

If these criterion are met, the release may proceed.

Monitoring of off-sitie liquid waste releases is required by Technical Specification 3/4.11.1.

If 1 EMF-49 is not operable, the Technical Specification allows the use of the additional sampling and analysis procedure previously described to perform a liquid waste release.

DESCRIPTION OF INCIDENT:

On February 8, 1988, the Liquid Waste Release Process Radiation Monitor (EMF) 1 EMF-49 was declared inoperable and a work request written to repair its local Loss of Sample Flow indication.

At approximately 1900 hours0.022 days 0.528 hours 0.00314 weeks 7.2295e-4 months , during shift turnover, Nuclear Chemistry Technician (NCT) A and Assistant Nuclear Chemistry Technician (ANCT) B were informed that 1 EMF-49 was inoperable.

On February 11, 1988, Duke Power Instrumentation and Electrical (IAE) personnel repaired the low flow indication on 1 EMF-49 by replacing a light bulb. The EMF was declared operable at 1255 hours0.0145 days 0.349 hours 0.00208 weeks 4.775275e-4 months .

At approximately 1500 hours0.0174 days 0.417 hours 0.00248 weeks 5.7075e-4 months , day shift Chemistry personnel started preparation for the release of Waste Monitor Tank (WHT) B under Liquid Waste Release (LWR) package 117. The tank was at 94% level. While utilizing OP/0/B/6500/15, xc no=M seas (9 SM

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Catawba Nuclear Station, Unit 1 o l5 l0 l0 lo14 l 1l 3 8l8 TEXT I# seen, se,se W feguf4W. ass, SM ADAC Alepuur M8J 1175 Radwasta Chemistry Procedure For Discharging A Monitor Tank To The Environment, a Chemistry. Technician recirculated the tank, verified the operability of 1 EMF-49, and took a sample of the tank for isotopic and chemical analysis. At this time, l

the main body o#, the procedure and the attached enclosures to the procedure were i

separated..The main body of the procedure went with the samples, while the enclosures went to a tray in the Radwasta Chemistry office.

Later that evening, at 1845 hours0.0214 days 0.513 hours 0.00305 weeks 7.020225e-4 months , NCT A arrived for shift turnover. The Technician was informed that 1 EMF-49 was again operable. Other topics of discussion were the status of the Boron Recycle System (EIIS:CA) (NB) Evaporator

.(EIIS:EVP) (which would require samples very soon) and the status of Floor Drain Tank to Waste Monitor Tank A processing (which required monitoring).

Approximately halfway through turnover, ANCT B arrived. This Technician was not present when the operability of 1 EMF-49 was discussed and did not read the turnover sheets.

Immediately following the turnover, NCT A requested that ANCT B start sampling the Evaporator and monitor the processing of the Floor Drain Tank. NCT A's goal was to finish a lot of work early because another Technician from Secondary

' Chemistry would be arriving for cross-training.

At'1915 hours0.0222 days 0.532 hours 0.00317 weeks 7.286575e-4 months , the HP Supervisor informed NCT A that LWR 117 was~being sent to Operations for signoff and that the liquid waste release would occur in the near future.

At 1945 hours0.0225 days 0.54 hours 0.00322 weeks 7.400725e-4 months , NCT C from Secondary Chemistry arrived at the Radwaste office for cross-training. He was familiarized by NCT A with certain aspects of the Waste Gas Storage System, then they both returned to the Radwaste office.

An Operator brought LWR 117 to the Radwaste office at 2015 hours0.0233 days 0.56 hours 0.00333 weeks 7.667075e-4 months . Also at this time, the Chemistry Supervisor came to the Radwaste office. NCT A asked the Supervisor if NCT C was qualified to independently veuly (IV) the WMT release procedure. The Chemistry supervisor stated that NCT C was qualified to IV the valve positions on the pre-release valve line-up. A few minutes later ANCT B returned to the Radwaste office and was instructed to perform the pre-release valve line-up with NCT C.

ANCT B asked NCT C if he was qualified to do the IV.

NCT C informed num that he was. ANCT B believed the NCT C was qualified to IV all procedure steps. NCT A did not mention to ANCT B that NCT C (who was being trained) could not IV the final release line-up and did not tell him to hold the procedure after completion of the pre-release line-up. ANCT B picked up the previously separated enclosure and performed the alignment to support a release if 1 EMF-49 was inoperable.

Since ANCT B had not read the shift turnover sheets, he still believed that 1 EMF-49 was not operable, as it had been inoperable during the previous night.

Because of this, he verified 1WL-366, 1WL-931, and 1WL-932, the EMF isolation valves, closed as directed by the procedure when the EMF.is-inoperable.

While the valve alignment was in progress, NCT A entered the data from the isotopic analysis into the Champlot Computer program. This data was part of the nonu seen.

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Amoveoo.No meoic4 w aes e:3,es P ACILifV asAME (13 00CK ET NUMis5R (2)

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AGE (3)

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"'V,0 0l0 0l4 0F 0 l6 1 Catawba Nuclear Station, Unit 1 0 l5 l0 lo l0 l4 Il I 3 8l8 Ol1l 0 f tXT f# mcry specs as regasren was acelesner Ar#C #ame JgErst (17)

LWR package. Also contained in the LWR package was the information about the operability of 1 EMF-49.

At 2040 hours0.0236 days 0.567 hours 0.00337 weeks 7.7622e-4 months , ANCT B and NCT C returned to the Radwaste office after completion of the pre-release valve alignments. ANCT B verified the LWR package was completed appropriately up to that point. Had the ANCT carefully reviewed the.

LWR, he would have noticed that lEMF-49 had been declared operable in the LWR Rate of Release Determination Form and in the main body of the procedure. Also during this review, the ANCT verified that the sample analysis was complete.

During this review, the ANCT did not recognize that only one sample was present, yet when the EMF is not operable, two samples are required.

When the verifications were completed, NCT A instructed ANCT B and NCT C to continue the release. NCT A then returned to the Evaporator to take samples.

NCT C was not qualified to perform IV of the final steps of the procedure prior to and during the release, but this IV was performed by him at this time.

It was intended by the Chemistry Supervisor that NCT A perform this IV.

After the release started, ANCT B signed that the Loss of Sample Flow light for 1 EMF-49 went out which would have indicated flow was going through the EMF. The light did not go out.

He later reported that he remembered the step as requiring a signature whether or not the light went out.

He informed NCT C that the low flow light would not go out because they had the EMF isolated and expressed his concern that the step should be N/A'ed instead of signed. NCT C accepted this explanation and verified the step.

The Technicians performing the release returned to the Radwaste office to verify flow was registering on the Control Room instrumentation. After a short delay to start the NB Evaporator pump out, this was completed. The Technicians returned to monitor the NB Evaporator pump out process.

At approximately 2115 hours0.0245 days 0.588 hours 0.0035 weeks 8.047575e-4 months , all three Technicians returned to the Radwaste office. Shortly thereafter, NCT A was informed by the Control Room Operator (CRO) that the Control Room 1 EMF-49 Low Sample Flow light was illuminated. NCT A attempted to clear the alarm by further throttling 1WL-893, Waste Monitor Tank Radiation Monitor Bypass valvo, to direct more flow through the EMF. The Technician called the CR0 back to learn the status of the alarm light.

It was still in the alarm state and the EMF had a lower count rate th.tn expected. NCT A returned to the EMF and found it to be isolated. The Technician decided to terminate the release by opening the local tank rv m.ulation valve and closing the local discharge isolation valve. ANCT B ani C C, who arrived af ter NCT A, placed the tank back in recirculation and isolatea the release path locally.

The CR0 had already terminated the release from the Control Room at 2118 hours0.0245 days 0.588 hours 0.0035 weeks 8.05899e-4 months . At 2119 hours0.0245 days 0.589 hours 0.0035 weeks 8.062795e-4 months , the tank was back in recirc at 49% level.

NCT A telephoned the Chemistry Supervisor and informed her of the unmonitored release. The Chemistry Supervisor discussed the proper course of action with the HP Supervisor and the Operations Shift Supervisor.

They decided to resample the contents af WMT B and perform the analyses and comparisons which would have been conducted if tim NF had been known to be inoperable.

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Catawba Nuclear Station, Unit 1 0 l5 l0101014 l 113 8l8 Olll0 0l0 0l5 0F TEXT fr snore space e roowned, was assessW NAC #esm MsJ f th The second sample results showed the isotopic activity level in the tank hereased to 78% of its previous value. The samples did not agree within 20%, so a third sample was taken after recirculation of the tank.

While the sampling was in progress, the Operations Shift Supervisor determined that the release required notification of the NRC within four hours. He made these notifications as well as informing the Compliance Duty Engineer. At approximately 0300 hours0.00347 days 0.0833 hours 4.960317e-4 weeks 1.1415e-4 months , the results of the third sample were determined and the total activity of the sample had dropped to 57% of the original value.

Per the Health Physics (HP) Procedure for LWR Requirements with the EMF inoperable, a comparison of isotopic activities from each sample was conducted.

The sum of these highest values was then used to determine a theoretical maximum activity sample. The sample still met all criterion for release.

CONCLUSION:

This incident is attributed to a personnel error. The information that 1 EMF-49 was operable never reached ANCT B and resulted in the misalignment of the EMF isolatien valves.

However, the information was available in several locations.

The logbooks and turnover sheets, which the ANCT did not have much time to review at turnover, contained the information. The LWR package, which the Technician did review and verify to be correct, contained several steps concerning operability of the EMF, its alarm setpoints, verification that the EMF was operable, verification that the low flow alarm worked, and only one set of sample data. Had the ANCT paid more attention to detail and verified the operability of 1 EMF-49, it is extremely unlikely that the incident would have occurred. The Technician was fully qualified to perform the procedure.

Additionally, the alignment error would very likely have been detected had NCT A independently verified all of the procedural steps involved, instead of partial verification by NCT A and parcial verification by NCT C, who was not qualified on the prxedure. NCT A was informed by the Chemistry Supervisor that NCT C was only qudified to IV the valve positions in the pre-release steps of the procedure. NCT A allowed NCT C to IV the final steps of the procedure.

There have been several occurrences of Technical Specification violations due to ick of attention to detail. Therefore, this type of event is considered to be recurring.

However, there have been no previous occurrences of Technical Specification violations due to unauthorized personnel performing a function.

CORRECTIVE ACTIONS:

IMMEDIATE Operations and Chemistry personnel terminated the release of WMT B.

SUBSEQUENT (1) Chemistry and HP personnel conducted further sampliag/ analysis to verify that discharge limits were not exceeded.

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"1?st ma 0l0 0l6 0F 0l 6 Catawba Nuclear Station, Unit 1 0 l5 j o l 0 l 0 l 4( 1l 3 8l8 011 l 0-TGAT raf more assee e deseauW. use ammament As#C # wise was (1M (2) Chemistry personnel' realigned the EMF isolation valves and verified the EMF to be aligned for service.

(3) The incident was discussed with the involved personnel with emphasis on paying attention to detail, proper verification of equipment status, proper turnover techniques, the priority of waste releases over other plant processes, and the allowable uses of-independent verification by Technicians.in cross-training.

SAFETY ANALYSIS:

The liquid contents of Waste Monitor Tank B which were not monitored during the release had been sampled before the discharge occurred. The isotopic activity

-was low enough to allow the release at 100 gym (the maximum flowrate) into.4920 gym Low Pressure Service (E) water flow, to comply with maximum permissible

+

concentration (MPC) guidelines. The E flow throughout the incident was 45,000 gpa..This provided approximately nine times the required dilution.

Interlocks E

on the release were set so that if E flow ever decreased to 20,000 gpm, the release would stop.. No decrease in E flow occurred.

The first. sample taken after the release had been terminated-showed total

activity levels of,78% the original value. The second sample after termination-of the release showed total activity levels of'57% the original value.

Monitoring of the tank-levels while the tank was-isolated, before and after the release, showed no level changes. This indicated that there were no additions to the tank contents during the release.

-A theoretical sample wac cretted from the maximum isotopic activities from each of the three samples. These maximums were then entered into the same calculations for Ecte of Release determination as the original sample.

The.results of the calculation showed that a 100 gpm discharge rate into a minimum 5500 spa E flow would be required for the proper MPC dilution. Based on the existing 45,000 gym E flow, approximately 8 times the required dilution flow was present.

From this data, no administrative limits were exceeded. This incident is reportable under-10 CFR 50.73, Section (a)(2)(1)(B). The health and safety of the public were not affected by this incident.

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ML20244C894

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