ML17340A762

Technical Evaluation of Electrical,Instrumentation & Control Design Aspects of Override of Containment Purge Valve Isolation & Other Engineered Safety Feature Signals for Turkey Point Nuclear Power Station,Units 3 & 4.

ML17340A762
Person / Time
Site:	Turkey Point
Issue date:	01/31/1981
From:	Cooper J EG&G, INC.
To:	Shemanski P Office of Nuclear Reactor Regulation
Shared Package
ML17340A763	List: ML17340A762 ML20003C255 ML20003C258 ML20003C261
References
CON-FIN-A-0231, CON-FIN-A-231 EGG-1183-4160, NUDOCS 8102270393
Download: ML17340A762 (19)

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~&&zCi 1183-4160 Energy Measurements Group January 1981 San Remen Operations TECHNICAL EVALUATIONOF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOL'ATION AND OTHER ENGINEERED SAFETY FEATURE SIGNALS FOR THE TURKEY POINT NUCLEAR POWER STATION, UNITS'3 ancI 4 by J. H. Cooper Approved for Publication

. R. Radosevic Department Manager This document is UNCLASSIFIED Derivative pQ Classifier:

Nacho as . ro enc Department Manager gag~

gyes Work Performed for Lawrence Livermore National Laboratory under U.S. Department of Energy Contract No. DE-ACO8-76 NVO 1183.

~P ABSTRACT This report documents the technical evaluation of the electrical, instrumentation, and control design aspects of the override of containment purge valve isolation and other engineered safety feature signals for the Turkey Point Nuclear Power Station, Units 3 and 4. The review criteria are based on IEEE Std-279-1971 requirements for the safety signals to all purge and ventilation isolation valves.

1' FOREWORD This report is supplied as part of the Selected Electrical, Instrumentation, and Control Systems Issues (SEICSI) Program being con-ducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Operating Reactors, by Lawrence Livermore National Laboratory, Field Test Systems Division of the Electronics Engineering Department.

The U.S. Nuclear Regulatory Commission funded the work under an authorization entitled "Electrical, Instrumentation and Control System Support," BSR 20 19 04 031, FIN A-0231.

The work was performed by EG8G, Inc., Energy Measurements Group, San Ramon Operations, for Lawrence Livermore National Laboratory under U.S.

Department of Energy contract number DE-AC08-76HV01183.

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TABLE OF CONTENTS

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1. INTRODUCTION.

2. EVALUATION OF TURKEY POINT NUCLEAR POMER STATION, UNITS 3 AND 4 3 2.1 Review Criteria 3 2.2 Containment Ventilation Isolation Circuits Design DescriPtion 2.3 Containment Ventilation Isolation System Design Evaluation.

2.4 Other Engineered Safety Feature System Circuits

3. CONCLUSIONS .

REFERENCES............... 9

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TECHNICAL EVALUATION OF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION AND OTHER ENGINEERED SAFETY FEAIURE SIGNALS FOR THE TURKEY POINT NUCLEAR POWER STATION, UNITS 3 AND 4 (Docket Nos. 50-250 and 50-251)

J. H. Cooper EGKG, Inc., Energy Measurements Group, San Ramon Operations 1'. INTRODUCTION Several instances have been reported where automatic closure of the containment ventilation/purge valves would not have occurred because the safety actuation signals were either manually overridden or blocked during normal plant operations. These events resulted from procedural inadequacies, design deficiencies, and lack of proper management controls.

These events also brought into question the mechanical operability of the containment isolation valves themselves. These events were determined by the U.S. Nuclear Regulatory Commission (NRC) to be an Abnormal Occurrence (878-5) and were, accordingly, reported to the U.S. Congress.

As a follow-up on this Abnormal Occurrence, the NRC staff is reviewing the electrical override aspects and the mechanical operability aspects of containment purging for all operating power reactors. On November 28, 1978, the NRC issued a letter entitled "Containment Purging During Normal Plant Operation" [Ref. 1] to all boiling water reactor (BWR) and pressurized water reactor (PWR) licensees. In a letter [Ref. 2] dated January 5, 1979, the Florida Power and Light Company (FPLC), licensee for the Turkey Point Nuclear Power Station, Units 3 and 4, replied to the NRC generic letter . A meeting was held on May 30, 1979 by the NRC staff and EGKG, Inc. (San Ramon Operations) personnel. In the meeting of May 30, 1979, during a conference call, and in letters of June 8, 1979 [Ref. 3] and December 13, 1979 [Ref. 4], the licensee described .the purge valve isola-tion system design of the Turkey Point Nuclear Power Station as discussed later in this report.

This document addresses only the electrical, i'nstrumentation, and control (EISC) design aspects of the containment ventilation isolation (CVI) and other engineered safety features (ESFs).

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2. EVALUATION OF TURKEY POINT NUCLEAR POWER STATION, UHITS 3 AND 4 2.1 REVIEW CRITERIA The primary intent of this evaluation is to determine following HRC staff criteria are met for the safety signals to all purge if the and ventilation isolation valves:

(1) Criterion no. 1 In keeping with the requirements of GDC 55 and 56 LRef. 5], the overriding* of one type of safety actuation signal (e.g., radiation) should not cause the blocking of any other type of safety actuation signal (e.g., pressure) for those valves that have no function besides containment isolation.

(2) Criterion no. 2--Sufficient physical features (e.g., keylock switches) are to be provided to facilitate adequate administrative controls.

(3) Criterion no. 3--The system-level annunciation of the overridden status should be provided for every safety system impacted when any override is active (see R.G. 1.47).

Incidental to this review, the following additional HRC staff design criteria were used in the evaluation:

Criterion no. 4--Diverse signals should be pro-

'1) vided to initiate isolation of the containment ventilation system. Specifically, containment high radiation, safety injection actuation, and containment high pressure (where containment high pressure is not a portion of safety injection actuation) should automatically initiate CVI.

(2) Criterion no. 5 The instrumentation and control systems provided to initiate ESF should be de-signed and qualified as safety-grade equipment.

~gt g Override:

ft ttt t gt f 1 t y f The signal is still present, and t gt it is blocked in order to perform a function contrary to the signal.

(3) Criterion no. 6--The overriding or resetting* of the isolation actuation signal should not cause any valve or damper to change position.

Criterion 6 in this review applies primarily to related ESF systems because implementation of this criterion for =containment isolation systems will be reviewed by the Lessons Learned Task Force, based on the recommendations in NUREG 0578, Section 2. 1.4 )Ref. 63. Automatic valve abilityy repositioning upon reset may be acceptable when containment isolation is not involved; consideration will be given on a case-by-case basis. Accept-would be dependent upon system function, design intent, and suit-able operating procedures.

2.2 DESIGN DESCRIPTION Each of the Turkey Point units has two ESF trains which cause isolation of the containment ventilation system. The initiating signals for each train, which are listed below, are combined as parallel inputs to form an "OR" gate.

(1) Automatic Si nals (a) High radiation (particulate or gas)

(b) Safety injection actuation (2) Hanual Si nals a onta>nment isolation; phase A - pushbotton (b) Containment isolation; phase 8 - pushbutton Each train includes the automatic and manual input "OR" gates, a retentive memory element, which is a lock-out relay with a manual reset, and a containment ventilation isolation control circuit.

The retentive memory is a device which retains the condition of the output that corresponds to the last input. This retentive memory element is not capable of overriding containment ventilation isolation signals and will not latch an override on the CVI. If a manual reset is attempted when a trip signal is present, the device will return to a trip-ped condition.

'Hhen either a monitored plant condition or: a manual input calls for isolation, the signal goes through the "OR" gate and trips the reten-tive memory element to the isolation state. The isolation valve control circuit operates to close the ventilation valve, and remains in that state until the retentive memory element is manually reset.

~gff Reset: fgdffffsignal gf The 1

has f

come 1 ff f and gone, and 1

the gf circuit is being cleared in order to return it to the normal condition.

Following manual reset, the retentive memory element remains in the reset condition until a subsequent trip signal (automatic or manual) occurs'he trip condition of the CYI is annunciated on the control panel; valve-position lights (full open/full closed) are provided.

2.3 DES IGN EVALUATION In their letter of December 13, 1979 (Ref. 4], the licensee for Turkey Point Nuclear Power Station, Units 3 and 4 has committed to limit containment purging during power operation (>25 power) to a total of 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> per year for the site, which includes purging of both units.

An override of the safety injection signal does not block or override the radiation or manual isolation signals. 'We conclude, there-fore, that NRC criterion no. 1 is satisfied.

There is no override in the CVI circuit; therefore, special physical features are not required. We conclude that criterion no. 2 is not applicable.

There are annunciators on the safety injection actuation signal, the containment high pressure signal, and the high radiation and contain-ment ciated ventilation isolation signals.

on When asked if SI override was the CVI panel, the licensee stated in the letter of October 27, annun-1980 [Ref. 7] that there is an annunciator for the override of safety injection targeted as "SI Blocked", and that "Containment Ventilation Isolation" override annunciation would be inappropriate. We conclude, that with the "SI Blocked" annunciator clearly visible from the containment ventilation control panel, NRC criterion No. 3 will be met.

Containment ventilation isolation is initiated by safety injec-tion (including a high containment pressure signal) as well as by either of two high containment radiation signals. Hence, the CVI system design includes diverse actuation signals and satisfies NRC criterion no. 4.

Both the CVI system and the equipment providing signals for are part of the plant safeguards actuation system.

it The licensee states in their letter of October 27, 1980 [Ref. 7] that the 'safeguards system is designed and qualified as safety-grade and that the CVI system also is safety-grade. We conclude, therefore, that NRC 'criterion no. 5 is satis-fied.

Resetting the safety injection signal cannot cause the CVI system to reset, nor will it cause automatic reopening of the containment ventila-tion valves. Clearing the CVI isolation signal requires manual operation of the reset. Reopening the valves also requires manual operation of the individual ventilation valve switches. We conclude, therefore, that NRC criterion No. 6 is satisfied.

2.4 OTHER ENGINEEREO SAFETY FEATURES (ESF) SYSTEM CIRCUITS The other engineered safety features (ESF) audited were contain-ment isolation Phase A. The other ESF system circuits are the same as the containment ventilation isolation (CVI) circuits with respect to overrides and valve reopening on reset. We conclude that the NRC criteria are met.

3. CONCLUSIONS The EI8C design aspects of containment purge valve isolation and other ESF signals for the Turkey Point Nuclear Power Station, Units 3 and 4 were evaluated using those design criteria stated in Section 2.1 of this report.

We determine that the CVI system design and the design of other fSF circuits meet the NRC staff criteria stated in Section 2.1 of this report.

REFERENCES

1. NRC/OOR letter (A. Schwencer) to NPPO, "Containment Purging During Normal Plant Operation," dated November 28, 1978.

2. NPPO letter (R. E. Uhrig) to NRC (A. Schwencer), "Docket 50-250, 251, Containment Purging During Normal Plant Operations, Turkey Point Nuclear Plant," dated January 5, 1979.

3. FPL letter (R. E. Uhrig) to NRC (A. Schwencer), "Containment Purging, Turkey Point Nuclear Station, Units 3 and 4," dated June 8, 1979.

4. FPL letter (R. E. Uhrig) to NRC (A. Schwencer), "Containment Purge,"

dated December 13, 1979.

5. U.S. Nuclear Regulatory Commission, Standard Review Plan, "Containment Isolation System" NUREG 76/087, Rev. , ect>on

6. U.S. Nuclear Regulatory Commission, "THI Short-term Implementation Action," NUREG-0578.

7. FPL letter (R. E. Uhrig) to NRC (T. Novak), "Turkey Point, Units 3 and 4, Docket Nos. 50-250 and 50-251, Containment Ventilation Isolation",

dated October 27, 1980.

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