PACIFIC GAS 6 ELECTRIC COMPANY

DIABLO CANYON NUCLEAR POWER PLANT

INDEPENDENT DESIGN VERIFICATION PROGRAM

INTERIM TECHNICAL REPORT NO. 49

REVISION 0

1

ADDITIONALVERIFICATION OF

CIRCUIT SEPARATION AND SINGLE FAILURE

REVIEW OF SAFETY-RELATED ELECTRICAL EQUIPMENT

PERFORMED BY

STONE 6 WEBSTER ENGINEERING CORPORATION

DOCKET NO. 50"275

LICENSE NO. DPR-76

PROJECT MANAGER

F. Sestak, Jr.

DATE 4 ~3

8307050149 830630PDR ADOCK 05000275R . PDR

PROGRAM MANAGER'S PREFACE

DIABLO CANYON NUCLEAR POWER PLANT - UNIT 1

INDEPENDENT DESIGN VERIFICATION PROGRAM

INTERIM TECHNICAL REPORT

ADDITIONAL VERIFICATION OF CIRCUIT SEPARATION

AND SINGLE FAILURE

REV IEW OF SAFETY-RELATED ELECTRICAL E(UIPMENT.

This is the forty-ninth of a series of Interim Technical Reports preparedby the DCNPP-IDVP for the purpose of providing a conclusion of the program.

This report provi des a des cripti on of the work done,

summary

and

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evaluation of the results, and conclusions of the IDVP with respect to theconcern of circuit separation and single failure review of safety-relatedelectrical equipment.

As IDVP Program Manager, Teledyne Engineering Services has approved thisITR. The methodology foil owed by TES in performing this revi ew andverification is described by Appendix A to this report.

ITR Reviewed and ApprovedIDVP Program ManagerTeledyne ngineeri g Ser vices

D. C. StratoulyAssi stant Project Manager

TABLE OF CONTENTS

Section Title ~Pa e

INTRODUCTION.. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ \ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1-1

SUMMARY . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 2-1

BASIS OF CONCERN................... ~ ~ ~ ~ ~ 3 1

3.1 EOI FILES. ~ ~ ~ ~ ~ ~ ~ ~ 4 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~'3 1

3.2 SCOPE OF ADDITIONALVERIFICATION........................... 3-2

ANALYSIS ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~'

~ ~ ~ 4-1

4.1 CIRCUIT SEPARATION...-....,.................,............... 4-1

4.2 SINGLE FAILURE. 4-2

„4.3 ACCEPTANCE CRITERIA..................... ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 4-2

4.4 DOCUMENTATION USED. 4-2

CONC LUSIONS ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ r 5 1

APPENDIX

PROGRAM MANAGER'S ASSESSMENT

SECTION .1

INTRODUCTION

Interim Technical Report (ITR) No. 34, Revision 1, describes all additional

verification work required to be performed based on the initial sample.

This ITR describes work performed in one of the areas of concern,

specifically, circuit separation and single failure review of safety-related

electrical components.

The Independent Design Verification Program (IDVP) review of the Auxiliary

Feedwater (AFW) System and the Control Room Ventilation and Pressurization

(CRVP) System Class IE electrical control circuits in enclosures (panels,

termination boxes) identified electrical circuits that were not separated by

the methods listed in the FSAR, Section 8.3.3. The IDVP also'dentified an

electrical component in the CRVP,System that did not meet the DCNPP-1 single

failure criteria.

The AFW and CRVP Systems are Design Class I (safety-related) systems. PGSE

agreed to make modifications to these systems to assure that the separation

and single failure criteria would be met. The IDVP recommended additional

verification to assure that similar concerns did not exist for other safety-

related systems. As a result, PGSE performed a review of all PGSE-designed

safety-related systems to ensure that the safety-related electrical circuits

meet FSAR single failure and separation criteria. As a result of the review,

1" 1

PGSE made modifications to comply with FSAR single faj.lure and separation

criteria. The lDVP verified the results of the PGRE review on a sampling

basis by reviewing electrical schematics and inspecting enclosure wiring

of four selected systems.

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SECTION 2

SUMMARY

PG&E reviewed the electrical and control circuitry for all PG&E-designed

safety-related systems required to achieve safe shutdown or mitigate an

accident. The review identified all mutually redundant circuits and their

connection to all devices, including transfer switches. The review included

a field verification to assure that cable/wire separation meets the FSAR

requirements. The IDVP selected a sample of the PG&E work to verify circuit

separation and to verify single failure criteria conformance for mutually

redundant circuits connected to a common device. The IDVP verification

included a field inspection of circuit separation in selected panels and

enclosures.

The results of 'the IDVP verification determined:

~ The PG&E analysis for the four sample systems was thorough and

complete.

~ The PG&E review resulted in the identification of separation and

single failure concerns similar to those addressed in:the initialsample. Modifications were subsequently made to provide consist-

ency with FSAR separation commitments.

2-1

~ The IDVP drawing review and field verification of the four sample

systems upon completion of the PGSE analysis and modifications

indicated that the FSAR separation and single failure criteria

were satisfied.

~ No further additional verification is required based on the satis-

factory results of the IDVP verification.

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SECTION 3

BASIS OF CONCERN

The IDVP review of instrumentation and control of the AFW System and the

CRVP System identified two areas of concern:

~ Several mutually redundant devices and circuits in control panels

for both systems were not separated in accordance with criteria in

the FSAR, Section 8.3.3.

~ An electrical component in the CRVP Control System did not meet

the DCNPP-1 single failure criteria for safety-related systems.

3.1 EOI FILES

Control panels containing AFW and CRVP system control circuits were field-verified for separation of mutually redundant circuits. As committed to in

the FSAR, Section 8.3.3, separation is required to meet the single failure

criteria. This review identified several instances of circuits with a

mutually redundant function connected to the same terminal block, exposed

wiring at end connections to devices and instruments not separated by at

least 5 inches, and mutually redundant circuits not separated by one of the

eight methods listed in the FSAR, Section 8.3.3. The concern is that due to

lack of separation, a single failure may result in the loss of mutually re-

dundant trains of a safety-related system. EOI File 8057 was issued to

address this concern.

3-1

Each redundant train of equipment in the CRVP System is powered from a

separate, redundant Class IE power source. Mutually redundant sources of

power, however, are brought together in one electrical control transfer

switch which is used to select the train to operate. Failure of this switch

could result in loss of electrical power to both trains of the CRVP System.

EOI File 8017 addressed this concern.

3.2 SCOPE OF ADDITIONALVERIFICATION

In response to ITR No. 34, PG&E committed to reviewing all PG&E-designed

safety-related systems and identifying the mutually redundant circuits

within these systems. PG&E then determined if the mutually redundant cir-

cuits and devices within the same enclosures were both properly identified

and noted as requiring separation. In addition, PG&E conducted a field

review of all mutually redundant safety-related circuits located in common

enclosures to ensure that they were separated as required by the methods

stated in the FSAR, Section 8.3.3.

Also, as part of the review, PG&E identified devices which had mutually

redundant circuits connected to them. When identified, a single failure

analysis was performed to determine the ability of the system to perform itsdesign basis function.

SECTION 4

ANALYSIS

Upon completion of the analysis performed by PGSE, the IDVP selected samples

of the PGSE-designed safety-related systems and verified the analyses. The

sample systems selected for verification were:

Component Cooling Water

Auxiliary Saltwater

Auxiliary Building Ventilation

125'V dc Emergency Power

4.1 CIRCUIT SEPARATION

The IDVP reviewed the circuit drawings to determine that PGSE identified

mutually redundant circuits and performed a field inspection of enclosures

in the above systems to determine if the installation of mutually redundant

circuits within the same enclosure met the separation criteria committed to

in the FSAR, Section 8.3.3. The IDVP verification did not identify any

cases where PGRE did not identify the systems'utually redundant circuits

or where separation in the field did not meet FSAR requirements. PG&E did

identify modifications that were required, and they were implemented in the

sample systems to ensure compliance with the FSAR separation methods.

4.2 SINGLE FAILURE

In addition to verifying the circuit separation, the IDVP also reviewed

PG&E's single failure analyses in the above four systems. PGSE provided

drawings marked to show where mutually redundant circuits were connected to

the same device. Where this occurred, PGSE performed a single failure

analysis to determine the ability of the system to perform its design basis

function. The IDVP reviewed these analyses to verify that all mutually

redundant circuits connected to the same device were identified. The IDVP

verification did not identify any cases where a single failure would

adversely affect the operation of these systems.

4.3 ACCEPTANCE CRITERIA

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The sample systems must satisfy the single failure criteria of IEEE Standard

279-1971. These systems must also meet the commitments in the FSAR, Section

8.3.3, regarding circuit separation.

4.4 DOCUMENTATION USED

Documentation required to verify PGRE performed reviews for circuit separa-

tion and single failure of safety-related electrical control equipment

consisted of the following:

4-2

~ DCNPP-1 schematic diagrams and connection 'diagrams for the four

selected sample systems color-coded by PGSE

~ PGSE-performed single failure analyses for those devices that had

mutually redundant circuits connected to them.

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SECTION 5

CONCLUSIONS

The conclusions concerning the additional verification of circuit separation

and single failure review of safety-related electrical equipment follow:

The PG&E analysis for the four sample systems was thorough and

complete.

~ The PGSE review resulted in the identification of concerns similar

to those addressed in the initial sample. Modifications were sub-

sequently made to provide consistency with FSAR separation

commitments.

~ The IDVP drawing review and field verification of the four sample

systems upon completion of the PGSE analysis and modifications

indicated that the FSAR separation and single failure criteria

were satisfied.

~ No further additional verification is required based on satis-

factory results of the IDVP verification.

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APPENDIX A

PROGRAM MANAGER'S ASSESSMENT

APPENDIX A

PROGRAM MANAGER'S ASSESSMENT

Independent review by TES of the tasks performed by SWEC to verify theDiablo Canyon Project (DCP) efforts was done in accordance with the IDVP PhaseII Program Management Plan and ITR-34.

ITR-34, Revision 1, issued on March 24, 1983, identified five (5) areasof concern which required additional verification. The work was performed bythe DCP and the conclusions were verified by SWEC.

This ITR describes the additional verification on circuit separation andsingle failure reviews of safety-related electrical equipment performed bythe IDVP on a sample basis. The sample consisted of four safety-relatedsystems which were drawn from all safety-related systems previously reviewedby the DCP to ensure that the electrical circuits met the FSAR single failureand separation criteria. Included in the verification were a review of theapplicable DCP electrical schematics and an on-site inspection of wiring inenclosures for the sampled systems.

The results of the IDVP verification determined that the DCP review wasthorough and complete, and that the FSAR requirements for separation andsingle failure criteria were satisfied. No EOI files were issued.

The IDVP concluded that the DCP review of circuit separation and singlefailure analysis in safety-related systems is satisfactory. Accordingly, nofurther additional verification is required.

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