ML20151E042

Sser Supporting Electrical Cable & Raceway Configurations for Plant

ML20151E042
Person / Time
Site:	Vogtle
Issue date:	07/18/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20151E031	List: ML20151E029 ML20151E042
References
NUDOCS 8807250341
Download: ML20151E042 (3)

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a EllCLOSURE SUPPLEllENTAL SAFETY EVALUATION REPORT FOR THE V0GTLE UNIf ?

ELECTRICAL SEPARATION CRITERIA BACKGROUND Vogtle Units 1 and 2 met the standard electrical separation criteria as outlined in IEEE 384-1974 with a few exceptions.

To establish separation distances which deviate from the standard separation distances specified in IEEE 384-1974, (reduced minimum separation) Georgia Power Company (GPC) performed a series of tests and analyses to establish reduced separation distances. This is permitted by IEEE 384-1974 and NRC Regulatory Guide 1.75 -(R.G.1.75).

Vogtle Final Safety Analysis Report (FSAR) Table 8.3.1-4 is the tabulation of alternate reduced minimum separation distances at V'

,e.

In Supplement No. 4 to NUREG-1137, "Safety Evaluation Report rclatei che operation cf Vogtle Electric Generating Plant, Units 1 and 2," (SSER 4) dated December 1986, the NRC staff approved the electrical cable separation criteria util1 zed in the design of Vogtle Units 1 and 2.

Subsequent to the reduced separation testing conducted in 1986, additional j

cable and raceway configurations were identified.

DISCUSSION To establish reduced separation distances for cable and raceway configurations not previously tested or analyzed, GPC through Wyle Laboratories performed a series of testing and analysis.

Ti.ese tests were conducted in accordance with criteria approved by the NRC staff for Vogtle in SSER 4.

In the tests, Yogtle cable configurations were used in the lab to replicate as much as possible the octual field installations.

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. The test method consisted of setting up cable configurations in which a cable selected on the basis of most severe ignition and fault terrperaturc, is designated as the fault cable. A fault (short circuiting) was applied to this cable until it opened the short circuit.

The effects of this short circuit on cable (desig-noted as target cables) in free air, adjacent trays, or conduits are monitored with thermocouples while energized with conservative values of voltage and current.

In addition the target cable during the tests were monitored for continuity.

After the test the cables were inspected and given an insulation and high potential test. The acceptance criterion for the target cables was the satisfactory comple-6 tion of the insulation resistance (greater than 16 x 10 ohms) and high potential tests (no evidence of insulation breakdown or flashover) with a potential of 7200 VDC applied for 60 seconds and a satisfactory demonstration of the capability of the target cables to conduct 100% of their rated currents before, during, and after the overcurrent test.

The results of the tests are documented in Wyle Laboratories Test Report No. 17959-02 dated December 1987 which was forwarded by GPC to NRC in a letter dated March 14, 1988 (Ref. 1).

GPC submitted in a letter dated June 16, 1988 (Ref. 2) answers and clarifications to the staff questions related to the worst case orientation of the cables, t" peak temperatures measured and insulation resistance tests.

The questions were raised and discussed in a telephone conference between the staff and GPC repre-sentatives on May 25, 1988.

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CONCLUSION 1

All the cable tested met the acceptance criteria.

For one configuration (Test 1/2), the 2/C No. 14 AWG cable jacket was blistered for 4" near the end of the rigid conduit. No cracks or openings were observed and the cable passed the ar.ceptance criteria.

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. The NRC staff has reviewed the test results and clarifications submitted by GPC and find that_ they provide a satisfactory basis for minimun separation distances for ccbles and raceways specified in the revised FSAR Table 8.3.1-4 for Vogtle Unit 2.

As stated in the NRC staff. letter to GPC, dated April 22, 1988 (Ref. 3), the application of these electrical separation criteria to Vogtle Unit 1 is subject to the requirements of 10 CFR 50.59.

Principal Contributors:

S. N. Saba, Electrical Systems Branch J. B. Hopkins, Project Directorate II-3 REFERENCES 1.

Letter to Document Centrol Desk, USNRC from J. A. Bailey, Project Licensing Manager, Georgia Power Company, "Plant Vogtle Units 1 and 2, NRC Docket 50-424, 50-425, Operating License ITF-68, Construction Permit CPPR-109, Electrical Separation Criteria", dated March 14, 1988, 2.

Letter to Document Control Desk, USNRC from J. A. Bailey, Project Licensing Manager, Georgia Power Company, "Plant Vogtle - Units 1 and 2, NRC Dockets 50-424, 50-425, Operating License NPF-68, Construction Permit CPPR-109 Electrical Separation Criteria", dated June 16, 1988.

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Letter to George F. Head, GPC from Jon B. Hopkins, NRC, dated April 22, 1988.

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