ML20012C509

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LER 90-009-00:on 900212,containment Purge Sys Heaters Not Being Verified to Be Running During Monthly Surveillance as Required by Tech Specs.Caused by Defective Procedures,Due to Incomplete Info.Procedures revised.W/900313 Ltr
ML20012C509
Person / Time
Site: Catawba Duke Energy icon.png
Issue date: 03/13/1990
From: Glover R, Owen T
DUKE POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-009, NUDOCS 9003220096
Download: ML20012C509 (6)
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Duke twtr Company yy,y y,4999 Cutatrba NuclearStation (L * /*O thr 2% .

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'\ DUKE POWER L . March.13,.1990 Document Control Desk' U. S. Nuclear Regulatory Commission Washington, D..C. 20555

Subject:

Catawba Nuclear Station Docket No. 50-413 LER 413/90-09 Gentlemen:

Attached is' Licensee Event Report 413/90-09, concerning TECHNICAL SPECIFICATION VIOLATION FOR INOPERABLE CONTAINMENT PURGE SYSTEM DUE TO m INCOMPLETE PROCEDURES.

This event was considered-to bc of no significance with respect to the health and safety of the public.

I ti Very truly yours, q Tony B. Owen Station Manager kob\LER-NRC.TBO i xc: Mr. S. D. Ebneter American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library  !

U S. Nuclear Regulator Commission The Exchange, Suite 245 j 101 Marietta Street, NW, Suite 2900 270 Farmington Avenue  !

Atlanta, GA 30323 Farmington, CT 06032 l l

.M & M Nuclear Consultants Mr. K. Jabbour 1221 Avenues of the Americas U. S. Nuclear Regulatory Commission j New York, NY 10020 ofCice of Nuclear Reactor Regulation. j Washington, D. C. 20555 INPO Records Center Suite 1500 Mr. W. T. Orders 1100 circle 75 Parkway HRC Resident Inspector Atlanta, GA 30339 Catawba Nuclear Station ff 9003220096 900313 m M t PDR ADOCK 05000413 /

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' " ' ' ' ' ' Technical Specification Violation For inoperable Containment ,

Purge System Due to Incomplete Procedures IVENT DATE (S; LER NUh8SE R ($1 51EPORT DAff 176 OTHER F ACILITIES INVOLVED (0)

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NAME TELE. HONE NUM8tR ARE A COD 4 R.M. Glover, Compliance Manager 8 10 13 81311 I l31 21 316 COMPLEf t ONE LINE FOR E ACM COMPONENT F AltS8Rt DESCRiS10 IN THi$ fiEPOts' (13l REPORTA LE p g y MA P TA E s CAUSE 8YSTEM COMPONENT NgfjC.

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On February 12, 1990, at approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, with Unit 1 in Mode 0, Defueled, and Unit 2 in Mode 1, Power Operation, a Performance and an Operations Engineer noted, during a review of ventilation procedures, that the Containment Purge (VP) System heaters were not being verified to be running during the monthly surveillance required by Technical Specifications. Although the relative humidity (RH) controller, which controls the automatic operation of the beaters, was being adjusted with the intent of automatically running.the heaters, a review of past test data revealed that RH never exceeded 50% (except for the first two tests on Unit 1, and one test on Unit 2). Since the operating band of the controller is 50% to 100% RH, it was evident that the heaters were never energized during the tests, which have been used since initial startup.

This incident is attributed to defective procedures, since the operation of the heaters was not being verified. The Unit 1 VP System was declared inoperable (Unit 2 VP was previously inoperable), and was properly retested. The procedures have been revised to ensure the heaters are operating.

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s. The Containment Purge [EIIS:VA] (VP) System is designed to maintain the Containment environment within acceptable limits for personnel access during 0 inspection, testing and maintenance activities, and to limit the release of any 1

contamination to the environment. The VP System uses two 50% capacity supply 3

air handling units and two 50% capacity exhaust filter [EIIS:FLT] trains.

During VP operation, purge exhaust heaters [EIIS:EHTR] are automatically staged on as necessary to maintain the relative humidity (RH) of air passing through L cxhaust filters below 70%. Three humidity sensors are located downstream of the

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purge exhaust heaters. Two of these (instrument loops VP5670 and 5680) function to isolate VP on high (>70%) RH, and the third loop (VP5690) functions to control the purge exhaust heaters.

Technical Specification 3/4.9.4, Containment Building Penetrations, requires I Containment penetrations [EIIS: PEN] to be either closed, or exhausting through an operable VP System using HEPA filters and activated carbon adsorbers, during core alterations or during movement of irradiated fuel within Containment.

Technical Specification Surveillance Requirement 4.9.4.2a states that the VP i I

System is demonstrated to be operable "At least once per 31 days by initiating flow through the HEPA filters and activated carbon adsorbers and verifying that i the system operates for at least 10 continuous hours with the heaters l operating". Technical Specification Bases state that " Operation of the system j with the heaters operating to maintain low humidity using automatic control for at least 10 continuous hours in a 31 day period is sufficient to reduce the i buildup of moisture on the adsorbers and HEPA filters". PT/1(2)/A/4450/01, Containment Purge Periodic Test is used to perform this surveillance. After verifying flow through both filter units, the procedure was to adjust 1(2)

VPP5690, CPFU Entering Air RH Controller [EIIS:XC] from its normal setpoint of approximately 60% RH, to 65% RH, with the intent of automatically running the heaters,1(2)HETR0528. After running VP on the filter mode for a minimum of 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, and recording flow, differential pressure (d/p) and RH every two hours, the humidistat, 1(2)VPP5690, was readjusted to its initial setpoint.

EVENT DESCRIPTION.

On February 12, 1990, at approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, with Unit 1 in Mode 0, Defueled, and Unit 2 in Mode 1, Power Operation, a Performance and an Operations Engineer noted, during a review of VP procedures, that PT/1(2)/A/4450/01 did not ensure that the VP heaters were operating (or would operate) during the monthly surveillance. This procedure review was within the scope of the ongoing effort of the System Expert Program, to review systems and related procedures to ensure that the intent of Technical Specifications and the FSAR is being met. When reviewing past test data, it was found that all tests (except the first two on Unit 1, and one test on Unit 2) recorded less than 50% RH during the test.

Since the heater controller,1(2)VPP5690, has an operating range of 50% to 100%

RH, it was evident that the heaters were not energized during the tests. These procedures have been used since initial startup. By 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br />, both A and B i

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O Trains of the Unit 1 VP System were declared inoperable (both Unit 2 VP Trains

" were already inoperable, due to Unit 2 being in Mode 1, with VP Containment

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Isolation Valves [EIIS:V] failed closed. Technical Specification 3.6.1.9 L requires these valves to be sealed closed in Mode'1, Mode 2, Startup, Mode 3,

< Hot Standby, and Mode 4, Hot Shutdown).

On February 25, 1990, PT/1/A/4450/01 was performed using a revised method:

4 rather than adjusting the controller to attempt to operate the heaters, a high humidity signal was simulated at the heater controller, IVPP5690, and the heaters were verified to be operating every two hours. During the last hour of the 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> test, however, a heater contactor failed, and Work Request 11126 IAE was. initiated. After installing another contactor, it was found that the master controller for the heater unit was not maintaining voltage, causing the contacts

. to chatter. The controller was replaced, and PT/1/A/4450/01 was successfully performed on February 26 and 27, prior to refueling. Both trains of the Unit 1

" VP system were restored to operable status by 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br />, on February 27.

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CONCLUSION This incident is. attributed to defective procedures, due to incomplete information. PT/1(2)/A/4450/01 did not contain steps to ensure that the heaters were operating during the continuous 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> test. These procedures have been

- revised to include such steps; a high humidity signal is now simulated at 1(2)VPP5690 to ensure that the heaters operate, and current readings are taken every two hours to verify their operation. The revised PT/2/A/4450/01 will be performed to verify Unit 2 VP System operability. Other safety-related ventilation procedures were reviewed.to see if a similar test method was being used, and it was found that heater operation was being properly verified by observing differential temperatures in these procedures. A Station Problem Report (SPR #CNPR-04721) has been initiated to facilitate testing, proposing that heater circuitry _be modified so that all four heater banks of 1HETR0528 are energized when the recirculation damper is fully closed, and that thermometers be_ installed upstream and downstream of the heaters.

A review of the Operating Experience Program shows another event involving VP equipment operation using an incomplete procedure, resulting in a Technical Specification Violation (see LER 414/89-006). This previous event involved the s

automatic opening of the VP Containment Isolation Valves due to a defective l

operating procedure not accurately describing the restart of the VP System.

l Technical Specification violations involving ventilation systems are a recurring l problem, and to deal with this, an extensive review of ventilation systems and l- associated procedures is currently in progress at Catawba, which will verify L that ventilation system testing is meeting the intent of Technical ,

Specifications, the Final Safety Analysis Report (FSAR), and Regulatory Guides dealing with ventilation systems. In LER 414/89-020, which described a Technical Specification 3.0.3 entry due to a clogged air flow monitor, a l comprehensive response was developed to deal with ventilation system problems l, _ __ _

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r. ensure that ventilation system testing is meeting design requirements:

I, Performance, Operations and Design Engineering will review available plant parameters for addition to the Performance Monitoring Database System to enhance the analysis and trending of ventilation systems performance data. Also, Design 3

L a Engineering will initiate a thorough and systematic review of ventilation system i design requirements and compare them against nominal operating data to ensure consistency with the FSAR and Technical Specification parameters.

CORRECTIVE ACTION SUBSEQUENT

1) Unit 1 VP system was declared inoperable.
2) Procedures PT/1,2/A/4450/01 were revised to verify that the heaters are on.
3) The revised PT/1/A/4450/01 was performed, and the Unit 1 VP System was returned to operability.

, 4) An SPR was initiated, proposing modifications which would facilitate VP testing.

5) Other safety-related ventilation procedures were reviewed to see if a similar test method was being used, and it was found that heater operation was being properly verified by observing differential temperatures.

PLANNED

1) The revised PT/2/A/4450/01 will be performed to verify Unit 2 VP System operability.
2) Performance, Operations, and Design Engineering will review available plant parameters for addition to the Performance Monitoring Database System to enhance the analysis and trending of ventilation systems (as well as other systems) performance data (from Planned Corrective Action 13, LER 414/89-020).
3) Design Engineering will initiate a thorough and systematic review of ventilation system design requirements and compare them against nominal operating data to ensure consistency with the FSAR and Technical Specification parameters (from Planned Corrective Action 14, LER 414/89-020).

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3 l 4) An extensive review of ventilation systems and associated procedures is currently in progress at Catawba, which will verify that

. ventilation system testing is meeting the intent of Technical

Specifications, the FSAR, and Regulatory Guides dealing with ,

ventilation systems. I SAFETY ANALYSIS.

The Bases for Technical Specification 3/4.9.4 state that " Operation of the system with the heaters operating to maintain low humidity using automatic ,

control for at least 10 continuous hours in a 31 day period is sufficient to 3- reduce the buildup of moisture on the adsorbers and HEPA filters". The VP exhaust heaters are used to satisfy this requirement. In addition, during VP operation, the exhaust heaters are automatically staged on as necessary to maintain the RH of air passing through the exhaust filters below 70%.

The design basis of the VP system has not been violated as a result of this incident for the following reasons. Filter unit heaters are mounted on each side of the filters to prevent adsorption of moisture when the VP exhaust fans are shutdown. These heaters automatically energize when the temperature in the vicinity of each respective filter unit decreases below approximately 110 degrees F. Carbon adsorbers are heated as necessary to maintain a suitable

" storage" environment, and high carbon adsorber load RH is alarmed. In addition to the protection provided by these heaters, VP will isolate when RH exceeds 70%. Also, during the performance of PT/1(2)/A/4450/01 in the past, RH has been recorded as being less than 50%.

The design functions of the VP system are outlined in FSAR Section 9.4.5.1: to clean up containment purge exhaust during refueling, to supply fresh air for contamination control when Containment (or incore instrumentation room) is or will be occupied, to exhaust Containment air to the outdoors through the purge exhaust filter trains whenever the VP System is operated, and to assure isolation of the system Containment penetrations. The only function which is safety-related, is the isolation of system Containment penetrations. The VP System will isolate on high radiation or high RH signals. The high RH signals would be generated from instrument loops VP5670 or VP5680, wnich are independent of the exhaust heater control loop in which the controller failed, VP5690. The-exhaust heater control loop, which energizes 1(2)HETR0528, performs no safety function.

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

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