GO2-83-859, Final Deficiency Rept,Condition 240 Re Loss of ESF Loads on Undervoltage Trip.Initially Reported on 830228.Sealed-in Circuit for Second Level Undervoltage Relays Deleted & Blocking Circuit Provided

Final Deficiency Rept,Condition 240 Re Loss of ESF Loads on Undervoltage Trip.Initially Reported on 830228.Sealed-in Circuit for Second Level Undervoltage Relays Deleted & Blocking Circuit Provided

ML20080L080
Person / Time
Site:	Columbia
Issue date:	09/22/1983
From:	Carlisle C WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
10CFR-050.55E, 10CFR-50.55E, GO2-83-859, NUDOCS 8309300063
Download: ML20080L080 (3)

Text

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.b Washington Public Power Supply System P.O. Box 968 3000GeorgeWashingtonWay Richland, Washington 99352 (509)372-5000 2

Docket No. 50-397

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September 22, 1983 '

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G02-83-859 Mr. J.B. Martin Regional Administrator 4 U.S. Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596

Subject:

NUCLEAR PROJECT N0. 2 REPORTABLE 10CFR50.55(e) CONDITION #240 1055 0F ESF LOADS ON UNDER VOLTAGE TRIP

References:

1. Telecon dated February 28, 1983, 1983 (QA2-83-050),

L.C. Floyd to D. Willet.

2. Letter G02-83-253 dated March 24, 1983 R.G. Matlock to R.H. Engelken.

3. Letter G02-83-573 dated June 24, 1983 C.S. Carlisle to J.B. Martin.

In accordance with the provisions of 10CFR50.55(e) your office was informed of the above reportable condition. The attachment provides the Project's final report on the above condition.

If you have any questions regarding this subject, please contact Roger Johnson, WNP-2 Project QA Manager, (509) 377-2501, ext. 2712.

Program Director, WNP-2 ecmm Attachment cc: Mr. W.S. Chin Mr. N.D. Lewis Document Control Desk, NRC 8309300063 830922 gDRADOCK05000 5

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.6 WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT N0. 2 DOCKET N0. 50-397 LICENSE NO. CPPR-93 10CFR50.55(e) CONDITION #240 LOSS OF ESF LOADS ON UNDERV0LTAGE TRIP FINAL REPORT Description of Deficiency On a degraded voltage condition (87.5% of rated voltage) in the critical bus (SM7 or SM8) supplying ESF loads; the second level undervoltage relays are required to trip the source breaker (i.e., startup/ normal or back-up source breaker) and initiate load shedding. The relays are self reset following closing of the alternate source breaker and the voltage on the critical bus returning to normal. However, the design incorporated a seal-in circuit for the 2nd level undervoltage relays requiring actuation of a manual switch to reset the relays following a degraded voltage condition. This resulted in the following:

1) An unsuccessful " auto" transfer from the startup/ normal source to back-up source, if the degraded voltage condition existed in the startup/ normal source, and,

2) ESF load breakers trip circuits being continuously energized until the relays are reset manually.

Safety Implication The situation described above, had it been lef t uncorrected, would have caused division 1 and 2 ESF loads to be unavailable in the case of a degraded voltage condition (87.5% of rated voltage) on buses SM7 and SM8. This situation would have remained unless operator corrective actions were taken. Had the condition occurred within the first 10 minutes following a design basis event, when no operator action is assumed, the plant could not be brought to a safe shutdown condition. The condition is considered to be a reportable deficiency under the provisions of 10CFR50.55(e).

Cause of Deficiency The condition is judged to have occurred as the result of a random engineering

design error made in BRI PED-218-E-5180 (Sheets 17 and 18). This conclusion is supported by the results of the review of other safety-related switchgear

, control circuits.

Actions to Prevent Reoccurrence The Project Design Control Procedure (WNP-2-017) was amended in August 1981 to provide documentary evidence of design verification on electrical Class lE design as it was issued. This should reduce the probability of such errors in the future.

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j Corrective Action Project Engineering Directive (PED) 218-E-4618 has been issued to implement i.

corrective action. The PED will effect the following changes:

e Delete seal-in circuit for 2nd level undervoltage relays.

e Provide a blocking circuit to prevent reclosing of the backup (ll5V) source breakers when the backup source is supplying the critical bus and an undervol-tage condition exists in the backup source.

I l Upon implementation of PED 218-E-4618, the SM7 and SM8 second level undervoltage i

relays will function as described in Sections 8.3.1.1.1 and 8.3.1.2.4.3.2 of

, the FSAR. Installation of this change is in progress and will be complete prior

to fuel load.

A review of high voltage switchgear and breaker control logic for safety-related 4

systems has been conducted to ensure that similar design deficiencies do not i exist. No similar seal-in circuits were found in any other safety-related 1

switchgear control circuit.

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