ML18093A472

Part 21 Rept Re Calibr Gas Leakage Problem in Exo-Sensors, Inc Containment Hydrogen Analyzer Sys.Caused by Design Deficiency Associated W/Calibr Gas Subassembly.Monitoring Program to Be Maintained for Period After Sys Mods

ML18093A472
Person / Time
Site:	Salem
Issue date:	10/23/1987
From:	Corbin McNeil Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
REF-PT21-87, REF-PT21-87-184-000 NLR-N87199, PT21-87-184, PT21-87-184-000, NUDOCS 8710290122
Download: ML18093A472 (5)

Text

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• Public Service Electric and Gas Company Corbin A. McNeill, Jr. Public Service Electric and Gas Company P.O. Box236, Hancocks Bridge, NJ 08038 609 339-4800 Senior Vice President -

Nuclear October 23, 1987 NLR-N87199 e,:

U.S. Nuclear Regulatory Commission N.

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Washington, D.C. 20555 )> CJ,.

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Gentlemen:

NOTIFICATION OF DEFECT; CONTAINMENT HYDROGEN ANALYZER SYSTEM SALEM GENERATING STATION UNIT NOS. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 In accordance with the requirements of 10 CFR 21, Public Service Electric and Gas Company (PSE&G) forwards the attached report relative to a calibration gas leakage problem present in the Salem Unit No. 1 and 2 Containment Hydrogen Analyzer Systems.

Due to a design deficiency, a loss of calibration gas may occur before the scheduled replacement interval of the storage bottles is reached thereby rendering the system inoperable.

The attached evaluation provides a more detailed discussion of the circumstances leading to the determination of reportability.

If there are any questions regarding this matter, please feel free to contact me.

Sincerely, Attachment

Document Control Desk 2 10-23-87 w/1 attachment c Mr. D. c. Fischer USNRC Licensing Project Manager Mr. T. J. Kenny Senior Resident Inspector-Salem Mr. W. T. Russell, Administrator USNRC Region I Mr. J. M. Taylor, Deputy Executive Director (3 Copies)

USNRC Regional Operations Mr. D. M. Scott, Chief Bureau of Nuclear Engineering Department of Environmental Protection 380 Scotch Road Trenton, NJ 08628

• ATTACHMENT EVALUATION OF DEFICIENCY CONTAINMENT HYDROGEN ANALYZER SYSTEM 1.0 SYSTEM DESIGN INFORMATION The Containment Hydrogen Analyzer Systems were originally provided by Exo-Sensor, Inc., 1220-B Simon Circle, Anaheim, CA 92806. Exo-Sensors, Inc. has since been purchased by Whitaker, Inc., 1955 North Surveyor Ave., Simi Valley, CA 93063.

A Containment Hydrogen Analyzer System consists of two Hydrogen Sensor Platforms mounted in containment and a Microprocessor/Control Electronics Assembly located in the control room area. There is one Containment Hydrogen Analyzer System for Salem Unit 1, and one Containment Hydrogen Analyzer System for Salem Unit 2.

Each Hydrogen Sensor.Platform consists of a hydrogen sensor, calibration piston, temperature transducer, pressure transducer, and a calibration gas supply. The calibration gas supply consists of a one-liter cylinder of 2% hydrogen gas, a one-liter cylinder of 6% hydrogen gas, a pressure regulator, and a shutoff solenoid valve.

The Containment Hydrogen Analyzer Vendor Manual, Qualification Test Report (10CFR50.49)r and Salem Generating Station Technical Specifications require that analyzer calibration be performed every 90 days during normal plant operation. The Qualification Test Report requires that analyzer calibration be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the occurrence of a LOCA and every .30 days thereafter. Without these calibrations the Containment Hydrogen Analyzers cannot perform their qualified function of post-LOCA hydrogen monitoring/control. The i~ability to monitor the

~eactor containment for post-LOCA hydrogen buildup could result in hydrogen concentration exceeding the explosive limit. If an explosion or fire should occur, post-LOCA recovery efforts and potential offsite exposures could be adversely affected.

The design basis for the Hydrogen Analyzer System requires that sufficient calibration gas be available to support all analyzer calibrations for a 24 month period (refueling outage to refueling outage) in addition to the required LOCA calibrations. The calibration gas cylinders should only require changing during refueling outages. Replacement of the gas cylinders cannot be accomplished following the onset of a LOCA.

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2.0 INITIAL IDENTIFICATION AND EVALUATION OF DEFECT Three deficiency reports identifying the excessive leakage problem were issued during the period December 1984 to June 1985 and, as a result, a meeting was held with a representative from Exe-sensors Inc. on August 22, 1985. At that time PSE&G was informed by Exe-Sensor that their experience had shown that the hydrogen analyzer calibration gas pressure regulator did not have a bubble tight shutoff and that leaks from the pressure regulator would not be contained by the down-stream shutoff valve due to its 100 psig service rating. Exe-Sensor recommended that the pressure regulator leakage problem be corrected by installing a

• shut off valve, tested for 1800 psig service, upstream of the pressure regulator.

PSE&G concurred with the above recommendation and, accordingly, Design Change Requests (DCRs) lEC-2175 and 2EC-2176 were initiated in this regard. These requests were subsequently not approved. However, concurrent with the initiation of the DCRs~

interim action was taken to establish a monitoring program whereby gas cylinder pressure would be periodically checked.

This monitoring program requires that containment entry be made during power operation to verify that a minimum pressure of 500 psig is available in all gas cylinders. The monitoring requirements were incorporated into the Containment Hydrogen Analyzer Vendor Manual in December 1985.

The 500 psig minimum pressure requirement is a compromise value and as such does not provide for all of the intended LOCA calibrations. Approximately 750 psig minimum pressure is required to provide for all LOCA calibrations. The 500 psig value will provide for the crucial calibration 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a LOCA and one 30 day post LOCA calibration. In its letter dated August 30, 1985, Exe-Sensors, Inc. provided analyzer accuracy degradation information that can be used when a 30 day post LOCA calibration cannot be performed. Based on the information provided, accuracy degradation is +/-0.3% hydrogen absolute per 30 days. Therefore, if one calibration is performed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a LOCA the expected accuracy drift will be +/-0.3% hydrogen absolute every 30 days thereafter. This will produce a worst case error of +/-0.9% hydrogen absolute for the 90 day post LOCA period. Thus, if the containment concentration after 90 days is 4% hydrogen the analyzer indication would be a value between 3.1%

and 4.9% inclusive.

3.0 CONCLUSION

A generic failure mechanism exists on all Containment Hydrogen Analyzer Systems provided by Exe-Sensor, Inc. to PSE&G. The failure results from excessive leakage due to a design deficiency associated with the calibration gas subassembly and, therefore, a defect exists as defined in 10 CFR 21.3. If this condition remained undetected, the resulting loss of safety function could result in a major reduction in the degree of protection provided to the public health and safety.

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4.0- CORRECTIVE ACTION Minor DCRs lSM-413 and 2SM-413 are being prepared to implement vendor recommended modifications. These DCRs provide for replacement of existing valves and fittings with components whose design will minimize leakage and assure availability of the hydrogen analyzers. Modifications to Salem Unit No. 1 will be accomplished during the present refueling outage. Modifications to Salem Unit No. 2 will take place during its next scheduled refueling outage.

The monitoring program presently in place shall be maintained for a sufficient period following implementation of system modifications in order to assure system integrity.

These commitments will be tracked to completion in the PSE&G Commitment Tracking System.

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