ML20210E246

Insp Rept 50-295/86-08 on 860312-13.No Violation or Deviation Noted.Major Areas Inspected:Plant Trips

ML20210E246
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	03/24/1986
From:	Muffett J, Westberg R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20210E241	List: ML20210E236 ML20210E246
References
50-295-86-08, 50-295-86-8, NUDOCS 8603270289
Download: ML20210E246 (3)

See also: IR 05000295/1986008

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U.S. NUCLEAR REGULATORY. COMMISSION

REGION III

Report No. 50-295/86008(DRS)

-Docket No. 50-295 License No. DPR-39

Licensee: Commonwealth Edison Company

P.O. Box 767

Chicago, IL 60690

Facility Name: Zion Nuclear Power Station, Unit 1

Inspection At: Zion, IL

Inspection Conducted: March 12-13, 1986

Inspector: R. A. Westberg 3/ M

Date

% CL W

Approved By: J. W. Muffett, Chi b/z4 /gg

Plant Systems Section Date

Inspection Summary

Inspection on March 12-13, 1986 (Report No. 50-295/86008(ORS))

Areas Inspected: Routine, announced inspection by one regional inspector of

plant trips - safety system challenges. It was conducted in accordance with

NRC Inspection Procedure No. 93702.

Results: No violations or deviations were' identified.

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DETAILS

1. Persons Contacted

Conro nweal th_E_d i s on Compa ny_( C Ecol

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• G. Plim1, Station Manager

• E. Fuerst, Superintendent Production

• W. Stone. Quality Assurance Supervisor

• A. Amoroso, Technical Staff Group Leader, Electrical

M. Bailey, Technical Staff Engineer

USNRC

• J. Kish, Resident Inspector

• Indicates those attending the exit meeting on March 13, 1986.

2. Review of Reactor Trip _ Caused _ by_1B_ Reac_ tor Trip Breaker

The purpose of this inspection was to review the facts relative to the

reactor trip on March 13, 1986. This review also included the excessive

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response time incident of March 3,1986, procedure reviews, interviews

with involved personnel, and inspection of the IB reactor trip breaker

(RTB).

a. Documents Reviewed

(1) Maintenance Procedure No. E015-1, " Reactor Trip Breaker

Maintenance," Revision 6.

(2) Test Procedure No. PT-5, " Reactor Protection Logic,"

Revision 14

(3) Schematic Diagram No. 22E-1-4884, " Reactor Trip Switchgear

Breaker," Revision J.

b. Inspection Results

The inspector's review of the procedures, the RTB schematic, and

interviews with involved personnel indicated that the reactor trip

was caused by the turbine trip which resulted when cell switch

No. 52h/RTB failed to open when the IB RTB was ir. properly racked

into place. When the bypass breaker was racked out to place the

IB RTB back in service, continuity through cell switch 52h enabled

the circuit logic which shut off the oil supply to the turbine

control valves causing a turbine trip. The reactor protection logic

then tripped the reactor 28 milliseconds later.

The inspector inspected the IB RTB and the switchgear cubicle.

At the inspector's request, an operator was able to duplicate the

condition that caused the turbine trip. With the breaker racked in

and electr:cally functional, it was possible for the breaker to be

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misaligned so that the cell switch 'ocated in the cubicle behind the

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breaker was not engaged. The function of this cell switch is to

i close when the breaker is racked out and to open when the breaker is

racked in place. In this case, the cell switch remained closed even

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thought the breaker was racked in place. Then when the bypass breaker

was racked out, a simila. cell switch closed tripping the turbine.

Based on the review performed by the NRC inspector, this incident

appears to be an example of an isolated personnel error.

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TheinspectorreviewedtheMarch3,jl986excessiveresponse

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time incident on the IB RTB, the sub, sequent maintenance, and the

! maintenance procedure. This maintenance did not appear to have

i any relation to the turbine / reactor trip on March 13, 1986.

i No violations or deviations were identified ir. this area,

i 3. Exit Interview

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The inspector met with licensee representatives in a telephone conference

on March 13, 1986, and summarized the purpose, scope, and findings of the

inspection. During the inspection, the inspector discussed with licensee

personnel the likely informational content of the inspection report with

i regard to documents or processes reviewed by the inspector during the

j inspection.

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