ML20043G644

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LER 90-008-00:on 900430,high Pressure CO2 Discharge Occurred on Auxiliary Feedwater Fire Protection Sys.Caused by Const/ Installation Deficiency in Solenoids.Solenoids Orientation Verified to Be Installed correctly.W/900614 Ltr
ML20043G644
Person / Time
Site: Catawba Duke Energy icon.png
Issue date: 06/14/1990
From: Hartzell C, Owen T
DUKE POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-008-02, NUDOCS 9006200521
Download: ML20043G644 (9)
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DUKE POWER June 14,-1990 Document Control Desk U. S. Nuclear Regulatory Com'nission '

Washington, D. C. 20555

Subject:

Catawba Nuclear Station Docket No. 50-414 LER 414/90-08 Gentlemen Attached is Licensco Event Report 414/90-08 concerning DEGRADED

' AUXILIARY FEEDWATER FIRE PROTECTION SYSTEM DUE TO CONSTRUCTION /

' INSTALLATION DEFICIENCY DURING INITIAL INSTALLATION AND A DEFICIENT ~

PRE-OPERATIONAL TEST PROCEDURE.

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

Very truly yours, l

Tony B. Owen b Aw Station Manager ken \LER-NRC.TBO xc: Mr. S. D. Ebneter American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library

'U. S. Nuclear Regulator Commicsion The Exchange, Suita 245 101 Marietta Street, NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, CT 06032 M & M Nuclear Consultants Mr. K. Jabbour 1221 Avenues of the Americas U. S. Nuclear Regulatory Commission New York, NY 10020 Office of Nuclear Reactor Regulation Washington, D. C. 205SS INPO Records Center Suite 1500 Mr. W. T. Orders j' 1100 Circle 75 Parkway NRC Resident Inspector i_

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LIC688.EI CONTACT Foa tMis tin uti 40ws tttsPaoNE Nywata 4.t a CODL C. L. Hartzell, Compliance Manager 8 l 0l 3 8i 31l 1 1 3 t16 5 1 1 CoMPtttt .NE tlht f oA B ACM compohtNt 8 Altunt of.Cmi.to IN ini. atront nas COUll Svlttw COwPo% INT "f $0 o p's 3 CAVlt S vitiv Cow *o%t%t 'jy(gC N

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On April 21,' 1990, at 14.10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, with Unit 2 in Mode 1, Power Operation, a high pressure carbon dioxide (CO2) discharge occurred on the Auxiliary Feedwater (CA)

Fire Protection (RFL System. The CO2 discharge occurred as a result of an unexpected steam release in the turbine driven pump pit during efforts to blow out clogged drain lines. With the turbine driven pump pit CO2 discharge header manualf.y isolated, the CO2 discharged into both motor driven pump pits.

However, system desityn is for discharge into only one pit. During investigation the r,olonoids on the three pilot valves were found to be installed backwards, which caused all three pit selector valves to open. This incident is attributed to c. Construction / Installation Deficiency in that the solenoids were installed backwards and that inspections did not identify this condition. This incident is also attributed to a Deficient Procedure in that the pre-operational test procedure did not identify failed pilot valve solenoids. The Unit 2 pilot valve solenoids' orientation was corrected. The similar solenoids on Unit I were inspected and found to be installed correctly. Post-maintenance testing of the Unit 2 solenoids was successfully performed. The present periodic surveillance test methods will be reviewed, llLM PX L 1)

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0l0 0l2 0F 018 BACKGROUND The high pressure carbon dioxide (CO2) system provides fire protection for the Auxiliary Feodwater [EIIS:BA] (CA) System pump [EIIS:P] pits as a function of the station Fire protection [EIIS:KP) (RF) System. Both high pressure CO2 systems, Unite 1 and 2, consist of eighteen high pressure CO2 cylinders arranged in two banks, main and reserve, located in the CA pump room of the Auxiliary Building [EIIS:NF]. In selection of the main or reserve banks, nine high pressure cylinders are aligned to provide fire protection to the one turbine

[EIIS:TRB] driven and two motor (EIIS:MO) driven CA pump pits. Check valves

[EIIS:V) in the manifold discharge header function with the activating system to discharge five cylinders into the turbine driven CA pump pit. All nine cylinders will discharge to a single motor driven CA pump pit. Three selector valves are provided in the discharge header which individually receive an activation signal associated with the pit that is to receive the CO2 discharge.

There is a 60 second time delay from receipt of a fire hazard signal to a CO2 discharge, and the discharge continues until the CO2 supply is exhausted. The system muct be reset before a second discharge is achievable.

The three selector valves, one for each pit, are pilot actuated by CO2 pressure from the CO2 cylinder discharge header. Three pilot and solenoid valve assemblies isolate the CO2 pressure from its associated selector valve until a fire hazard signal is received from a pit. Once a signal is received, the solenoid and pilot will open, allowing CO2 pressure to the top chamber of the selector valve, which then opens to discharge to the appropriate pit. The solenoid valves are two way, normally closed, soft synthetic seat valves manufactured by Skinner Electric Valve, reference number V5L26985 (UL/FM approved).

Technical specification (T/S) 3.7.10.3 requires the high pressure CO2 system to be operab;e whenever equipment protected by the CO2 system is required to be operable. With the CO2 system inoperable, within one hour a continuous fire watch for affected areas where redundant equipment is located must be established. For other affected areas, an hourly fire watch must be established.

EVENT DESCRIPTION During this incident, Unit 2 continuously operated in Mode 1, power Operation.

On April 21, 1990, at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, operations (OPS) personnel were attempting to pressurize the Unit 2 Auxiliary Steam [EIIS:SA] (SA) supply line to the CA Pump Turbine in order to blow out with steam the debris that was suspected to have accumulated in the SA line drains. The approach to be taken to pressurize the line was reviewed by the Control Room Operators (CRos) and was appropriately identified to all personnel involved, although written procedures did not exist.

A Nuclear Operator Specialist (NOS) verified that the isolation valves in the drain lines that contained the trash were closed. When the SA line was pressurized steam escaped into the turbine driven CA pump pit through a yma .. . . . cm i ... . u. . t,y

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.Catcwba Nuclear Station. Unit 2 0 l6 l0 l0 l0 F l1l 4 9l0 0 l 0l 8 0F var c a . < = =.e mm.u nn 0l0 0l3 0l 8 partially open valve, 2SA008, CA pump No. 2 Steam Supply Drain Orifice Inlet Isolation. The steam release was the result of debris being caught under the seat of 2SA000 preventing it from properly closing, and resulted in an inadvertent actuation of the CA pump pits high pressure CO2 fire protection system. The CO2 system, previously isolated to the turbine driven CA pump pit, discharged to both motor driven CA pump pits. After the room was ventilated and checked with air monitors, a continuous fire watch was established. At 1650 hours0.0191 days <br />0.458 hours <br />0.00273 weeks <br />6.27825e-4 months <br /> on April 21, the CO2 system was switched to the reserve bank of cylinders and the T/S action statement for an inoperablo CO2 system was entered. At 2100 houre, it was observed that 5 of the 9 main bank cylinders had discharged.

On April 22, the high pressure CO2 system was inspected by the Safety Group.

The pilot valve pressure switchs indicated that all three selector valves received pilot pressure for actuation. On April 23, Design Engineering support was requested to assist in determining the cause of the simultaneous actuation of all three selector valves.

On April 24, troubleshooting the CO2 system control cabinet under Work Request (W/R) 46490 ops identified that all solenoids were receiving the correct electrical signals. The solenoid actuation was checked by signals initiated from the control panel and by a heat source on the thermostats in the pump pits.

On all initiating signals, only the appropriate (selector valve) pilot valve solenoid received an actustion signal, indicating that no problems existed within the electrical circuitry of the high pressure CO2 system.

On April 26, W/R 6228 SWR was used to refill the discharged high pressure CO2 cylinders. With the cylinders disconnected from the header (both main and reserve), 700 psig nitrogen (H2) was used to pressure test the system. Without an electrical actuation signal to the pilot solenoids (solenoids closed), it was observed that N2 was escaping from the exhaust vent in the pilot pressure port of the pilot valve. On April 26, W/R 2558 KES was initiated to investigate the failure of the pilot and solenoid valves, 1

On April 30, the three selector valve pilot / solenoid valve assemblies were removed from the system. The valves were pressurized with N2 and the valves i would not prevent the N2 from passing through. A review of the assembly drawing (CNM 1206.08-0093) revealed that the solenoid was installed backwards on the l pilot valve. All three solenoids were reversed and the assemblies were reinstalled into the system. On May 1, a final check out of the system using N2 l pressure indicated that no N2 was escaping from the exhaust vent and that the i pilot / solenoid valve assemblies were isolating properly. l

! l On May 3,1990, Maintenance Engineering Services (KES) initiated pIR 2-C90-0156 J l to evaluate past operability of the high pressure CO2 system, including if thero  !

was a sufficient concentration of CO2 to extinguish an actual fire in three CA l l pump pits. A Maintenance Engineering Services (KES) review indicated no work I l had been performed on the pilot / solenoid valve assemblies since initial 1 installation. On May 15, Design Engineering concluded that the required design )

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0l0 Op Ol_8 concentrations could not be achieved with a CO2 discharge into more than one CA pump pit and that the system was inoperable with the pilot valve solenoids installed backwards. Operability-has been restored with the solenoid orientation corrected.

Refilling of the cylinders and repairs to system leaks discovered during the N2 pressure test were complete on May 17. The cylinders were reconnected to the header, and the high pressure CO2 system was returned to service. The T/S action requirements were exited at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on May 17.

CONCLUSION This incident is attributed to a Construction /In stallation Deficiency in that individuals performing the initial installation of the selector valve pilot / solenoid assemblies installed the solenoids backwards. The final system walkdown inspection also missed identifying that the solenoids had been

[ installed backwards. The assembly drawings used for the initial installation and inspection clearly identify the solenoid valve orientation, with port "P" labeled as the inlet and port "A" labeled as the outlet. The "A" and "P" ports are also clearly stamped into the body of the solenoid. By review of the system i turnover package and the final inspections, it can be concluded that the '

appropriate instructions and information (i.e. drawings) were available to the individuals performing the task, and that the installation was incorrect by those performing the initial installation and inspection. The high pressre CO2 fire protection system was therefore identified as complete and ready for service, and provided to the operating organization in this deficient condition.

As a result of this incident, the Unit I high pressure CO2 system selector valve i pilot / solenoid valve assemblies were inspected. All solenoids were verified to '

be installed correcti,y. Unit I was unaffected by this incident.

This incident is also attributed to a Deficient Procedure in that the Pre- j operational Test Procedure did not adequately test the system for a failed pilot valve solenoid. Procedure TP/2/A/1400/05C, CO2 Fire Protection System-Auxiliary Feedwater Pump Functional Test, requires manual isolation of the discharge headers to all three pits as a prerequisite. The manual isolations remained j closed during the electrical system testing. To verify CO2 concentrations }

during the pre-operational test the manual isolation for the pit being tested '

was opened with the other two manual isolations closed. During the test, there was no verification that the two selector valves, and pilot / solenoids, which did not receive an actuation signal remained in the closed position. l s

The Diesel Generator [EIIS: GEN] (D/G) Fire Protection utilizes a low pressure  !

CO2 system of similar design. Procedure TP/l(2)/A/1400/05B, CO2 Fire Protection System-D/G Building Functional Test, was reviewed and found to be adequate in j its test method of verifying pilot valve response. During this test, pressure i gauges were installed at the pilot line connection to the upper chamber of the

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selector valves. During CO2 concentration testing, the appropriate selector valve was verified to open by pressure received through the pilot line. Thu opposite selector valve was verified to remain closed (i.e. that no pressure was received through the pilot valve). During this test, the isolation valve for the D/G Room not receiving a discharge was manually closed (similar to the high pressure CO2 test of the CA Fire Protection System).

The present surveillance testing being performed on the high pressure CO2 system does not include a verification of selector valve response. If the selector valves do not respond properly to a system actuation, the CO2 discharge concentrations could be reduced below that which is required for the hazard area. The N2 pressure test (post-maintenance test) performed during this incident verified that the solenoids and pilot valves would hold pressure and that this incident's failure mode has been corrected. This N2 pressure test and other applicable tests of the selector valves will be evaluated for inclusion in the surveillance testing requirements.

During the past 24 months, there have been no unsuccessful actuations of a fire protection system due to incorrect initial equipment installation or due to deficient pre-operational testing. This incident is considered to be the result of an isolated deficiency within the fire protection system's operational readiness. The deficient pre-operational test procedure and the deficient final system walkdown inspection existed together to lead to this incident. If either had been adequately performed, this incident would have been prevented.

Inspections of the Unit 1 high pressure CO2 system piping (EIIS: PSP] ,

configuration and the Units 1 and 2 low pressure CO2 system pre-operational tests verify that these deficioacies do not exist in similar areas of the fire protection system.

During the past 24 months, there have been no unsuccessful actuations of a nuclear safety system due to incorrect initial equipment installation; however, there has been one incident due to deficient pre-operational testing. As identified in LER 413/89-023, the Control Room Ventilation System failed to provide adequate flow with a single outside air intake open during a normally j scheduled surveillance test. The pre-operational test and previous surveillance '

test were performed with both intakes open. The pre-operational test was found I to be deficient due to not testing all possible modes of system alignment. This i and other incidents related to ventilation systems has lead to developing a task i group to review the adequacy of testing of ventilation systems. Deficient I pre-operational test procedures resulting in unsuccessful actuation of safety ]

systems is considered to be a recurring problem per the Nuclear Safety Assurance guidelines.

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1) The electrical actuation signals of the high pressure CO2 system were inspected, and found to be working properly (reference W/R 46490 OPS).
2) The high pressure CO2 header was pressure tested using N2, and it was observed that pressure was escaping from the exhaust vent of the pilot valves (reference W/R 6228 SWR).
3) The two thermal links in the turbine driven CA pump pit ventilation system dampers were replaced (reference W/R 46490 OPS).
4) The solenoid's orientation was corrected on the three pilot valves (reference W/R 2558 MES).
5) The Unit 1 solenold's orientation was verified to be installed correctly.
6) A post-maintenance N2 pressure test was performed on the high pressure CO2 header, and verified that the solenoids would hold until an  !

actuation signal is received (reference W/R 6228 SWR). '

7) Performance and Design Engineering met to discuss possible improvements within the high pressure CO2 system design documents and station expertise.

PLANNED

1) The present methods of testing the operability of CO2 fire protection systems will be evaluated to datermine if additional testing is necessary, to insure that the surveillance requirements of T/S are being met.

SAFETY ANALYSIS The CO2 system does not perform a safety function, but does provido protection for safety related equipment. If a fire had occurred in the CA turbine driven pump pit, the three hour rated fire barriors separating this pit from the adjacent CA motor driven pump pats would have prevented the fire from spreading.

Safe shutdown would have been assured using the motor driven pumps. Similarly, if a fire would have occurred in one of the motor driven pump pits, the three hour fire barriers would have prevented the spread to the turbine pit. Safe shutdown would have been assured using the turbine pump. The fire boundary wall separating the Unit 2 CA pump has not been degraded such that it cou.'.d not have provided the three hour fire rating requirements.

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1) The detection and control system for the high pressure CO2 system remained operable while the mechanical actuation of the system was inoperable. If a '

fire would have occurred, a detector would have operated and a signal would '

have been received in the Control Room. The fire brigade would have responded to effect fire extinguishment. *

2) If the CO2 design concentration would not have been achieved, come CO2 '

would have discharged into the affected pit. This should have provided some firme control and slowed the fire some until the fire brigade l responded.

3) The discharge of CO2 into all three pits would not have affected operability of any of the pumps. For example, if a fire occurred in the  :

turbine pit resu) ting in the discharge of CO2, the CO2 discharged into the other pits woul/ cot render the motor driven pumps inoperable.

The health and sa.- of the public were maintained during this incident.

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