05000413/LER-1987-001, :on 870105,inadvertent Radioactive Gas Release Occurred Causing Auxiliary Bldg Ventilation Sys to Swap from Bypass to Filter Mode.Caused by Failure of Waste Gas Sys Drain Trap T-04

:on 870105,inadvertent Radioactive Gas Release Occurred Causing Auxiliary Bldg Ventilation Sys to Swap from Bypass to Filter Mode.Caused by Failure of Waste Gas Sys Drain Trap T-04

ML20235S088
Person / Time
Site:	Catawba
Issue date:	07/13/1987
From:	Torre J, Tucker H DUKE POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-87-001, LER-87-1, NUDOCS 8707210543
Download: ML20235S088 (9)

LER-1987-001, on 870105,inadvertent Radioactive Gas Release Occurred Causing Auxiliary Bldg Ventilation Sys to Swap from Bypass to Filter Mode.Caused by Failure of Waste Gas Sys Drain Trap T-04

Event date:
Report date:
4131987001R00 - NRC Website

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On Jenuary 5, 1987, at approximately 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, an inadvertent radioactive gas release occurred. At the time of the release, personnel working on a Nuclear Station Modification, were stroking valves on the Waste Gas (WG) System. The Auxiliary Building Ventilation (VA) System swapped from the Bypass mode to the Filter mode due to a Trip 2 condition on the Auxiliary Building Ventilation Radiation Monitor. Unit 1 and Unit 2 were at 100% power at the time of this incident.

Cause Code X, Other, has been assigned to this incident due to the failure of WG Drain Trap T-04.

Cause Code E, Management / Quality Assurance Deficiency, has been assigned to this incident due to sue of an inadequate work control program, the use of which has been subsequently deleted.

In addition, no established methods were provided for determining the operational control groups for systems to be used during the work planning phase. Cause Code A, Personnel Error, has been assigned to this incident due to violation of procedures and a Station Directive and due to insufficient investigation of the cause of the ventilation filter swap. Cause Code D, Procedure Deficiency, has also been assigned to this incident. The NRC Response Requirement Procedure incorrectly identified the automatic VA swap due to EMF-41 Trip 2 as an Engineered Safety Feature (ESF) actuation.

This report is being provided as a voluntary report. At the time of this incident, this VA swap to the Filter mode was thought to be an ESF actuation; however, a

further review revealed that this is a normal mode of operation and does not

/ 11 constitute an ESF actuation.

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-- 010l1 0l1 Ol2 OF 0l 8 TEXT IW more sonce a reeuwed, use addoroonal NRC form 366Ksh17l BACKGROUND

- A Nuclear 9tation Modification (NSM) is a planned change to a structure, system or conponent at an operational Nuclear Station and is accomplished in accordance with the requirements and limitations of applicable codes, standards, specifications, licenses, and safety restrictions. An NSM request form is normally initiated by the Projects Services Section at the station. Once the design of the NSM is completed, the appropriate design drawings and information are transmitted to the Construction Maintenance Division (CMD).

CMD will assemble the Project Team Commitment Package (COMPAK) through a series of meetings involving C4D, appropriate station representatives, and Design Engineering, if necessary.

Implementation of modifications has been performed under the work request program in conjunction with the shutdown request (F-13A) program. An F-13A is used to document installation activities. All work performed under F-13As must have a companion work request to document follow-up activities.

One step of the COMPAK development is the initiation of the required F-13As and NSM Work Requests containing the required system isolation.

Projects Services shall approve the NSM cnd notify station groups, as appropriate, of the NSM implementation.

The Projects Services accountable engineer is to ensure that copies of marked drawings are sent to Operations or Chemistry prior to return of the affected system to operable status.

The Waste Gas (WG) System (EIIS:WE) is a closed loop system which transfers, receives, processes and contains radioactive gases from contaminated fluids. Decay tanks (EIIS:TK) are used in the system for storage of these gases.

There are four gas traps (EIIS:TRP) located in the WG system at low point drains.

These. traps are designed to allow liquid to drain into a sump without releasing gas.

As the gas / liquid mixture enters the trap, the gas is forced out of the top of the trap and into the suction of one of the WG compressors.

The Auxiliary Building Filtered Exhaust System (EIIS:VF) is the portion of the Auxiliary Building Ventilation (VA) System that serves areas of the Auxiliary Building which are subject to potential contamination.

During normal plant operation, two filtered exhaust trains operate as two 50% capacity components.

Each filter train is equipped with a bypass section, which is the normal mode of operation. The VA radiation monitor (EIIS:IL) (EMF-41) monitors twelve points throughout the Auxiliary Building every hour, sampling each point for five minutes.

Upon indication of a radiation level equal to or above 3000 counts per minute (cpm) EMF-41 enters a Trip 1 condition, and a yellow light will become illuminated on the EMF panel. Upon receiving indication of a radiation level equal to or above i

4000 cpm, EMF-41 will enter a Trip 2 condition.

In Trip 2, a red light will become illuminated on the EMF panel and an audible alarm (EIIS:RA) will sound in the Control Room. Upon receiving a Trip 2 indication, the VA system will automatically swap to direct air flow through the filter trains. At the time of this incident, Technical Specification 3.3.2 was interpreted that any automatic actuation of VA from the Bypass to the Filter mode is an Engineered Safety Feature (ESF) actuation.

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Sigfy(AL Syy VEam Catawba Nuclear Station. Unit 1 0 l5 l0 l0 l0 l 4l1 l 3 8 l7

-- 0 l 0l1 Dl 1 Ol 3 OF g lg TLxt IH more spece e reeuwed, use addstoonal NRC Form 366Kal(1h The Unit Vent Airborne Monitor continuously monitors the gaseous, iodine, and particulate activity levels in the Auxiliary Building Ventilation System and other potentially radioactive sources which are released through the Unit Vent. The Unit Vent Airborne Monitor consists of three EMF monitors, which are EMF-35, EMF-36, and EMF-37. EMF-36 is the gaseous activity monitor, and it is limited to a maximum of 1.4 mrem / day of noble gases to be released through the Unit Vent. A Trip 2 indication of any of the three EMF's will isolate the Containment Purge Ventilation (VP) and Containment Air Release and Addition (VQ) Systems and trip the VA System.

Technical Specification 3.11.2.1 requires that the dose rate due to radioactive materials released in gaseous effluents from the site to areas at and beyond the site boundary for noble gases be less than or equal to 500 mrem / year to the whole body.

DESCRIPTION OF INCIDENT NSM CN-50110 Revision I was written to provide level instrumentation and reach rods on seven of the WG Suction Header Low Point Drain Valves (EIIS:V), the Recycle Holdup Tank Eductor Low Point Drain Valve, and the Recycle Holdup Tank Line Low Point Drain valve.

The NSM was approved by the Station Manager on November 20, 1984. The use of F-13A programs for the installation of station modifications was scheduled to cease at commercial operation of Unit 2.

At that time, all F-13A's were to be converted to work requests. This date was extended to approximately January 1, 1987, for certain modifications agreed upon by Station, QA, and CMD personnel. After receipt of NSM CN-50110 Rev. 1, CMD began assembly of the COMPAK.

On August 13, 1986, the responsible CMD Mechanical Technical Support Technician initiated Shutdown Request F-13A F00725 to install the reach rods on the nine WG drain valves.

F-13A F00725 was marked NO ISOLATION REQUIRED to perform work. On September 3, 1986, an Integrated Scheduling Engineer marked Operations (OPS) as the operational control group on F-13A F00725.

On September 25, 1986, Projects initiated Work Request 11168 NSM for stroking of the nine WG drain valves.

On September 29, 1986, Projects completed the Implementation Plan for Work Request 11168 NSM. On December 1, 1986, CMD contacted OPS prior to beginning work, and the OPS Unit Supervisor signed the F-13A for CMD to begin work. During the first tow weeks of December, preliminary work on the NSM was in progress.

On approximately December 18, 1986, the CMD crew began installing the reach rods onto the WG drain valves. During this time, the CMD crew had the NSM package containing F-13A F00725 and the Implementation Plan for Work Request 11168 NSM; however, Work Request 11168 NSM was not with the NSM package. On January 5, 1987, the CMD crew completed the installation of the reach rods. At this time, CMD began stroking the valves to verify operation of the reach rods. At 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, Health Physics (HP) noticed high background radiation on a local frisker in the Decon Room.

HP and Radwaste Chemistry (RW) began to search for the source of the radiation. At 1145 hours0.0133 days <br />0.318 hours <br />0.00189 weeks <br />4.356725e-4 months <br />, HP discovered EMF-41 in Trip 1 condition and notified Control Room personnel. At 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />, RW discovered that Waste Gas Decay Tank (WGDT) C had experienced a pressure loss of between 30 and 40 pounds. RW suspected that a drain trap had failed. At 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br />, RW notified HP of the gas leak problem. RW isolated a WG drain trap, isolated purge from the Unit 1 and Unit 2 Volume Control Tanks, and tripped both WG NMC F02U 366A 49 63:

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"^a Catawba Nuclear Station. Unit 1 ol5l0l0[0l4l1l3 8l7 0l0l1 g lg d1 0l4 OF TE31 IN more nonce a memed, one entorener NRC form 386Ksll17) compressors. At 1237 hours0.0143 days <br />0.344 hours <br />0.00205 weeks <br />4.706785e-4 months <br /> EME-41 experienced a Trip 2 alarm which realigned VA to the Filter mode. Control Room personnel acknowledged apparently the audible alarm without recognizing EHF-41 Trip 2 as being the source. At 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br />, RW

' discovered the CMD crew stroking the WG drain valves. At this time, RW realized that WG Drain Trap T-04 must have failed. RW began to' verify the position of the nine WG valves. At 1319 hours0.0153 days <br />0.366 hours <br />0.00218 weeks <br />5.018795e-4 months <br />, RW isolated WGDT C.

At 1340 hours0.0155 days <br />0.372 hours <br />0.00222 weeks <br />5.0987e-4 months <br />, RW notified the Shift Supervisor of the gas leak. At 1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br />, RW discovered valve IWG-340, WG Suction Header Low Point Drain #3, was 75% open and valve IWG-350 WG Suction Header Low Point Drain #6, was cracked open. RW closed both. valves. RW placed WGDT C into service and monitored it for leakage. No leakage was found. At 1425 j

hours, RW placed WG compressor A into service. HP obtained a gas sample in order q

to make the release determination. At 1427 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.429735e-4 months <br />, RW placed WG compressor B into 1

service. At 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, a Staff Health Physicist found EMF-41 in Trip 2 and reset i

the Trip 2 signal without notifying Control Room personnel.

The Staff Health l

Physicist thought OPS was aware of the Trip 2 signal. He knew that the gas leak j

problem had been identified and controlled. At 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br />, RW and other HP l

personnel discussed the EMF status; however, they were aware of the Trip 1

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condition only. The Unit 2 Nuclear Control Operator (NCO), while performing a walk through of the Control Room, discovered the Unit 2 VA in the Filter mode. The Unit 1-NCO discovered the Unit 1 VA in the Filter mode. Both NCOs discussed the VA alignment with the Shift Senior Reactor Operator and the Unit 2 Supervisor. Being unaware of the EMF-41 Trip 2 condition, they believed VA had been inadvertently left in the Filter mode and the decision was made to realign VA to the Bypass mode.

The Shift Supervisor and the Unit 1 Supervisor were not notified of the VA swap.

At 1724 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.55982e-4 months <br />, the Unit 2 NCO realigned the Unit 2 VA to the Bypass node. At 1812 hours0.021 days <br />0.503 hours <br />0.003 weeks <br />6.89466e-4 months <br />, the Unit 1 NCO realigned the Unit 1 VA to the Bypass mode.

j On January 6, 1987, at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, the Staff Health Physicist, while discussing deportability of the incident, informed the Unit 1 NCO of the EMF-41 Trip 2.

A review of the Alarm Typer and the EMF Strip Chart revealed that a VA swap to the Filter mode had occurred.

The NCO informed the Shift Supervisor that VA had swapped to the Filter mode on the previous day. At 1740 hours0.0201 days <br />0.483 hours <br />0.00288 weeks <br />6.6207e-4 months <br />, OPS notified the NRC of the EFS actuation in accordance with procedure RP/C/B/5000/13, NRC l

Notification Requirements.

CONCLUSION At the time of initial NRC notification, this incident was determined to be reportable due to the ESF actuation of automatically realigning VA to the Fi tered mode as specified in RP/C/B/5000/13. This automatic realignment of VA resulted from an EMF-41 Trip 2 actuation. Further review of FSAR Section 9.4.3 has J

determined that the realignment of VA to the Filtered mode due to an EMF-41 Trip 2 actuation is a normal mode of operation used to meet ALARA considerations. The realignment of VA to the Filtered mode on a LOCA signal constitutes an ESF actuation.

Due to the nature of this incident and the fact that there is no report'able event, several cause codes have been assigned.

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Cause Code X, Other, has been assigned to this incident due to the failure of WG

- Drain Trap T-04.

The trap failed ot maintain a water seal, resulting in a-radioactive gas release to Waste Evaporator Feed Tank Sump B and thus to the Auxiliary Building and out of the Unit Vent.

The increased radiation level caused an EMF-41 Trip 2 signal resulting in the automatic realignment of VA to the Filtered mode. RW initiated a Work Request to investigate and repair the failure of WG Drain Trap T-04.

Investigation revealed corrosion sediment in the trap. The i

trap was cleaned and the internals replaced. Functional verification was j

successfully performed and the work request completed on January 20, 1987, at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />. On January 21, while CMD and RW were stroking the WG valves per Work

. Request 11168 NSM, WG Drain Trap T-04 failed again. RW initiated another Work Request to investigate and repair. Corrective maintenance was completed; however, the trap did not pass its functional verification. Maintenance personnel plan to remove the trap from the system for further testing. Any other appropriate action will be initiated as required.

WG Drain Trap (EIIS:TRP) T-04 is an Erwel Type A-250 Compressed Air Drain Trap. A review of NPRDS revealed no reportable applications of this trap.

This failure is not reportable to NPRDS.

Cause Code E, Management / Quality Assurance Deficiency has also been assigned to this incident. The continuing use of the F-13A program along with the work request program lent confusion to the processing, handling, and installation of station modifications.

In addition, no established methods were provided for determining the operational control groups for systems to be used during the work planning phase.

The use of F-13A programs for the installation of station modifications was 3

scheduled to cease at commercial operation of Unit 2 (September 1, 1986). At that time, all F-13A's were to be converted to work requests. This date was extended to I

approximately January 1, 1987, for certain modifications agreed upon by Station,

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QA, and CMD personnel. NSM CN-50110, Rev. I was one of the extended modifications.

i During the technical approval review for F-13A F00725, Integrated Scheduling incorrectly identified OPS as the operational control group. The CMD creu thus, contacted OPS prior to starting work on the F-13A.

This resulted in RW, the eetual operational control group, not being aware of the work being performed. During the investigation of this incident, Chemistry and OPS expressed concerns of this i

problem also occurring with the use of work requests. Project Services incorrectly

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routed the NSM package and marked-up drawings for NSM CN-50110 Rev. I to OPS j

instead of RW.

This prevented RW from having knowledge of the modification being installed.

All modification work done under an F-13A must have a companion work request to document follow-up activities or that follow-up activities are not required. Work Request 11168 NSM was the follow-up work request for F-13A F00725 and was written to stroke the WG valves after installation of the reach rods. When the CMD crew started work on F-13A F00725, the follow-up work request was not with the package.

The CMD crew felt that the use of an F-13A allowed them more freedom with the I

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, mC5.asw,nm system due to past experiences during the pre-operational phase. An F-13A was perceived to return control of equipment / systems to the Construction Department.

With the F-13A marked as not requiring isolation and with the follow-up work request not with the package, the CMD crew felt justified in operating the W9

- valves as required to ensure proper installation of the reach rods.

Cause Code A, Personnel Error, has also been assigned to this incident due to violation of procedures and a Station Directive. Upon actuation of the EMF-41 Trip 2 signal, an audible' alarm sounded in the Control Room. A red Trip 2 indicating light and an annunciator light illuminated on the EMF panel.

Personnel in the Control Room acknowledged the audible alarm without taking proper response action as stated in Operations Management Procedure (OMP) 1-8, Authority of Responsibility of Licensed Reactor Operators and Licensed Senior Reactor Operators. Control Room personnel when interviewed had no knowledge of the alarm or who acknowledged the alarm. A Staff Health Physicist reset the EMF-41 Trip 2 signal, extinguishing the red Trip 2 indicating light and the annunciator light, without approval from or

. notifying Control Room personnel. This was in contravention of Station Directive i

3.15, Activities Affecting Station Operations or Operating Indications and OMP 2-16, Control Room Conduct. Cause Code A. Personnel Error, has also been assigned l

' due to insufficient investigation. The Unit 1 and 2 NCOs discovered the VA systems in Filtered mode prior to shift turnover. They discussed the system status with the Unit 2 Supervisor and the Shift SRO. Being unaware of the EMF-41 Trip 2 condition, the decision was made to return the VA systems to the Bypass mode. The Shift Supervisor was not informed. The NCOs, Unit Supervisor and Shift SRO did net thoroughly investigate the reason for VA being in the Filtered mode, taking into account the earlier WG release into the Auxiliary Building. The EMF-41 Trip 2 signal and the subsequent VA realignment were not recognized until 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on January 6, 1987.

Cause Code D, Procedure Deficiency has also been assigned to this incident.

RP/C/B/5000/13 incorrectly identified the automatic VA swap due to EMF-41 Trip 2 as an ESF actuation.

l There have been no previous Licensee Event Reports involving failure of a WG Drain Trap or the F-13A Program exhibiting inadequate work controls.

CORRECTIVE ACTION

(1) WG Decay Tank C was isolated.

(2) Valves 1WG-340 and 1WG-350, which were left open, were closed.

(3) A Work Request was initiated and completed to investigate and repair WG Drain Trap'T-04.

(4) This incident was reviewed with involved CMD personnel.

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(5) OPS reviewed this incident with all shift personnel.

(6) OMP 2-16, Control Room Conduct, was revised to require Control Room personnel to verbally notify other appropriate Control Room personnel when acknowledging alarms.

(7) A Technical Specification interpretation for Technical Specification 3.3.2 stating that only the realignment of VA to the Filtered mode on a LOCA signal constitutes an ESF actuation was initiated and approved.

(8) Station Directive 3.0.3, Management of Shutdown Request was deleted.

(9) Station Directive 3.10.1, Operational Control of Systems, was revised to include Projects Services, Planning, and CMD to distribution of boundary drawings.

(10) Maintenance Management Procedure 1.0, Work Request Preparation, was revised to ensure that the responsible planner will determine and indicate on each work request which group has operational control of the system / component being worke.d.

1 (11) All HP personnel were informed that EMF Trip 1 and Trip 2 signals / lights can be reset only with permission of Control Room personnel.

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(12) RP/0/B/5000/13, NRC Notification Requirements, was revised to incorporate the l

Technical Specification Interpretation for Technical Specification 3.3.2.

1 (13) Station Directive 4.4.4, Processing Nuclear Station Modifications, will be revised to delete use of the F-13A program and to ensure that all NSM packages i

are routed to the appropriate operational control group.

(14) 'The use of more detailed Implementation Procedures will be initiated.

(15) Maintenance will complete testing of WG Drain Trap T-04 and initiate any other appropriate action.

SAFETY ANALYSIS

Upon receiving the EMF-41 Trip 2 signal, the VA Filtered Exhaust Fans swapped to the Filter mode as designed.

In this alignment, all VA exhaust was routed through carbon filters prior to release out the unit vent. HP analysis of this release indicated the contents were noble gases and tritium. The VA carbon filters have no filtering effect on noble gases or tritium. A radioactive gas leak of this type is bounded by FSAR Section 15.7.1, Radioactive Waste Gas System Leak or Failure. The maximum activity in a single WG decay tank is limited by Technical Specification 3.11.2.6.

This limit assures that in the event of an uncontrolled release of the tank's contents, the resulting whole body exposure to an individual at the exclusion area boundary will not exceed 0.5 rem._ _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _. _ _ _ _

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- 0 l0l1 0l1 0l8 OF 0l8 TEKT w more space a reouart use endmoner NRC Forrn 36sunt sin The release to the environment was monitored by 1 EMF-36, and IEMF-36 did not experience any high radiation alarms during the release. The estimated total content of the release was 65.94 Curies. The whole body dose at the site boundary was 0.0136 mrem. This is not a contravention of Technical Specification 3.11.2.

Dose was assessed and assigned to the eight individuals directly involved in the area of the release, Room 213, Gas Decay Tank Drain Pump Room, and Room 214, Chemical Drain Tank Room, which are located on the 543 elevation of the Auxiliary Building. The total dose assigned was 51 mrem with the highest individual dose being 23 mrem.

This LER is being provided as a voluntary report.

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

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July 13, 1987 Document Control Desk

. U.'S. Nuclear Regulatory Commission

' Washington, D. C.

20555

- Subject: Catawba Nuclear Station, Unit 1 Docket No. 50-413 LER 413/87-01-01 (Revision 1)

Gentlemen:

Pursuant to 10 CFR 50.73 Section (a) -(1) and (d), attached is Revision 1 to Licensee Event Report 413/87-01 concerning an inadvertent waste' gas release due to failure of a waste gas drain trap. This event was considered'to be of no significance with respect to the health and safety of the'public.

Very truly yours,

.y fWL.

Hal B. Tucker I

JGT/68/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

'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