ML17297A596

Advises That IE Circular 81-12, Inadequate Periodic Test Procedure of PWR Protection Sys, Was Forwarded to Listed Licensees on 810722

ML17297A596
Person / Time
Site:	Palo Verde, Columbia, Diablo Canyon, San Onofre, Rancho Seco, Washington Public Power Supply System, Satsop, Trojan
Issue date:	07/22/1981
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML17297A594	List: ML17297A593 ML17297A596
References
NUDOCS 8107280317
Download: ML17297A596 (10)

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UNITED STATES NUCLEAR REGULATORY COMMISSION REGION V 1990 N. CALIFORNIABOULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94599 July 22, 1981 MEMORANDUM FOR:

ALL THOSE ON IE CIRCULAR DISTRIBUTION LIST FROM:

IE, REGION V

IE CIRCULAR NO. 81-12:

INADEQUATE PERIODIC TEST PROCEDURE OF PWR PROTECTION SYSTEM The attached IE Circular No. 81-12 was issued this date to the following licensees:

l.

Arizona Public Service Company (Palo Verde 1, 2

8 3, Docket Nos.

50-528, 50-529, 5"50-".530.

2.

Pacific Gas 8 Electric Company (Diablo Canyon Units 1

8 2, Docket..

Nos.

50-275 5 50-323).

3.

Portland General Electric Company (Trojan, Docket No. 50-344).

4.

Sacramento Municipal UtilityDistrict (Rancho

Seco, Docket No. 50-312).

5.

Southern California Edison Company (San Onofre Units 1, 2

8 3, Docket Nos.

50-206, 50-361, 8"50-"362).

6.

Washington Public Power Supply System (WNP-1, WNP-2, WNP-3, WNP-4, 8 WNP-5, Docket Nos.

50-397, 50-460, 50-508, 50-509 8 50-513).

Enclosures:

1.

Transmittal Letter 2.

IE Circular No. 81-12 i

81072803i7 8i0722 PDR ADOCK 05000528 8

PDR

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SSINS No.:

6830 Accession No.:

8103300406 IEC 81-12 h

jt Descri tion of Circumstances:

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'UNITED STATESUCLEAR REGULATORY'COMMISSION.,j '

'FFICE OF~,INSPECTION AND ENFORCEMENT~

WASHINGTON;."D. C. '20555,.-,.:

r 4r j.....July;22.

1981 l"

IE Circular No. 81-I2:

INADEQUATE PERIODIC TEST PROCEDURE OF, PHR PROTECTION SYSTEM n

i On November 30,

1980, ground isolation procedures were being carried out to locate an electrical ground in the,.125V dc,bus No. I at the St. Lucie Nuclear Power Plant.

Part of the procedure requires deenergizing the dc control power to the reactor trip circuit breakers (TCBs).

These breakers are designed to trip (fail-safe'ode) on undervoltage upon loss of dc control power.

Referring to Figure 1, the four TCBs (TCB 1,3,5, and 7) that are supplied control power from dc bus No. I did not trip immediately (because of binding) on undervoltage when control power was deenergized.

The operators did verify that the shunt trip for each of the four TCBs was functioning.

Operators also verified that the redundant TCBs from dc bus No.

2 (TCB 2, 4, 6, and 8) tripped on similar undervoltage conditions, and, in fact, inadvertently caused a plant trip while testing.

Investigation into the problem by the licensee identified the cause of failure as 'an out-of-adjustment condition in the linkage mechanism of the undervoltage trip device.

This adjustment problem, together with the lack of cleaning and periodic relubricating of the trip shaft mechanism, is the subject of IE Bulletin 79-09 which was issued April 17, 1979.

While shutdown, the undervoltage trip mechanism on each of the above four faulty TCBs was adjusted and verified to operate satisfactorily.

Investigation by the licensee revealed that the reactor protection system (RPS) periodic test procedure in use at the time did not verify the trip function of the undervoltage trip coil independent of the shunt trip coil.

Referring to figure 1, it can be seen that during a reactor trip test at this facility, these coils operate simultaneously causing the trip opening of the associated TCBs.

This, arrangement of the RPS and the trip test procedure may be simila'r for other PWRs.

BWRs may use similar circuit breakers in safety systems; therefore, similar indequacies in their circuit breaker test procedures may exist.

Following adjustment

'of the linkage mechanism of the undervoltage trip device the licensee instituted a revised surveillance test procedure to check the unde<-

voltage and shunt trip devices independently and to insur e proper breaker operation.

Although not shown in Figure 3., the undervoltage trip coil and the shunt trip coil are separately fused so that test procedure changes resolved the problem at St. Lucie.

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I EC, 81-12 July 22, 1981 Page 2 of 2 Recommended Action for Holders of 0 eratin Licenses and Construction Permits:

It is recommended that holders of operating licenses and construction permits review for applicability the specific items presented in the "Description of Circumstances."

It is further recommended that the procedure for surveillance testing of trip circuit breakers be reviewed and revised as necessary to provide independent testing of each trip function, including position verification to ensure that the breaker actually trips.

If the trip circuit breakers do not have provisions for independent testing of each trip function, including position verification, then appropriate modifi-cations should be made to include such features (e.g., local pushbuttons for the shunt and undervoltage trip coils, separately fused circuits for the shunt and undervoltage trip coils, etc).

No written response to this circular is required.

If you need additional information with regard to this subject, please contact the director of the appropriate NRC Regional Office.

Attachments:

1.

Figure 1

2.

Recently issued IE Circulars

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RECENTLY ISSUED IE CIRCULARS Attachment 2

IEC 81-12 July 22, 1981 Circular No.

Sub'ect Date of Issue Issued to 81-10 81-09 81-08 81-07 81-06 Steam Voiding inthe'eactor 7/2/81 Coolant System During Decay Heat Removal Cooldown

,Containment Effluent Wate'r,.-7/3.0/81 That Bypasses Radioactivity Monitor Foundation Materials",,,',;;,

5/29/81 "I

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" Control of.,Radioactively

" ",'/14/81

'ontaminated Material

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Potent.ial Deficiency:.'Affecting, 4/14/81 Certain 'Foxboro 20, 'to'0 Milliampere Transmitters All power reactor facilities with an OL and CP All power reactor facilities with an OL or CP All power reactor facilities with an OL or CP All power reactor',

facilities wittj+afij OL or CP All power reactor facilities with an OL or CP 81-05 81-04 Self-Aligning Rod End Bushings for Pipe Supports

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1 The Role of Shift Technical Advisors and Importance of Reporting Operational Events 3/31/81 4/30/81 All = power reactor facilities with an OL or CP All power reactor facilities with an OL or near-term OL 81-03 Inoperable Seismic Monitoring 3/2/81 Ins trumen tati on All power reactor facilities with an OL or CP 81-02 Performance of NRC-Licensed Individuals While on Duty 2/9/81 All power reactor facilities (research 5 test) with an OL or CP OL = Operating Licenses CP

= Construction Permit

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