05000285/LER-1976-010, Suppl to LER 76-10/03L:on 760401,high Power Margin to Trip Meter B Drifted from 4.2% to 6% Power.Caused by Drift of Feed Back Limiter Module 19-317-2X.Module Calibr & Operated Satisfactorily

Suppl to LER 76-10/03L:on 760401,high Power Margin to Trip Meter B Drifted from 4.2% to 6% Power.Caused by Drift of Feed Back Limiter Module 19-317-2X.Module Calibr & Operated Satisfactorily

ML20087K805
Person / Time
Site:	Fort Calhoun
Issue date:	04/08/1976
From:	William Jones, Mehaffey R OMAHA PUBLIC POWER DISTRICT
To:
Shared Package
ML20087K809	List: 05000285/LER-1976-010, Suppl to LER 76-10/03L:on 760401,high Power Margin to Trip Meter B Drifted from 4.2% to 6% Power.Caused by Drift of Feed Back Limiter Module 19-317-2X.Module Calibr & Operated Satisfactorily
References
FC-149-76, LER-76-10-03L, LER-76-10-3L, NUDOCS 8403260324
Download: ML20087K805 (5)

LER-2076-010, Suppl to LER 76-10/03L:on 760401,high Power Margin to Trip Meter B Drifted from 4.2% to 6% Power.Caused by Drift of Feed Back Limiter Module 19-317-2X.Module Calibr & Operated Satisfactorily

Event date:
Report date:
2852076010R00 - NRC Website

text

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LICENSEE EVENT REPORT 50-28s/76-lo 1 1

CONTROL OLOCK: l l l l l LEASE PRINT ALL RECUiRED INFIRM ATI 1 G l AME LICFNSE NUVUE R YL 1YPE

, @ l Nl El Fl Cl Sl 1l l0l0l-l0l0l0l0l0l-l0l0l [4 l 1 l 1 l 1l 1l l0 l3 l 7 09 14 15 25 26 30 31 32 CATEGORY Ty f DOCKET 'NUMutR EVENT DATE REPORT DATE O 1 CONT l l l l I,l l0 l 5 l 0 l-l 0l 2l 8l 5l l0l4l0l1l7l6l lo l4 l0 l8 l 7l 6l-7 0 57 $U 59 60 61 00 69 74 75 00 EVENT DESCR;PTION

( o l During operator checks of the Variable High Pover Margin to Trip Meter it was noted l 7 89 80 EE l that B Hirh Power Marcin to Trip had drifted from h.2 percent to 6 percent power. Al 7 89 60

@ l subsequent check of the high pcwer trip point showed a high power trip would occur l 7 89 80 EE l at 106.2 percent power. .A 1 percent calimetric error would have resulted in an l 7 89 00

$ I actuni trio point of 107.2 percent which exceeds the limit of 106.5 percent. (con't) l 7 89 mg 80 SYSTEM CAUSE CCMPONENT COMPONENT CODE CODE COMPONENT CODE SUPPLER MANUFACTURER 410LATON E lIl Al lEl 7 89 10 11 lIl Nl Sl Tl Rl Ul 12 17 lN l 43 lB l1 l6 l 5 l 44 47 W48 CAUSE DESCRIPTION 90 l The Bell and Howell 19-317-2X feed back limiter module used to gcnerate the high l 7 89 80 35 l power trip setpoint was found to have drifted. The module was calibrated and op l 7 o9 oo Ql [ opera.ted satisfactorily. l FACILITY METHOO OF STATUS  % POWER OTHER STATUS OSCOVERY OGCOVERY DESCRIPTON 1

7 8 9

$ 10 l1l 0l 0l 12 13 l NA l 44

@45 l

46 Operator Checks 80 l

ACTMTV CO$ TENT RELEASED OF RELEASE AMOUNT OF ACTMTY LOCATON OF RELEASE DE L2J LzJ l NA I I I 7 8 9 10 11 44 45 80 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTON

, H 1010l 0l Lz_l I na I 7 89 11 12 13 80 PERSONNEL INJURIES NUMBER DESCRIPTON H l0l0l0l11 12l 7 89 NA l

80 OFFSITE CONSEQUENCES

" M I NA l 7 09 80 LOSS OR DAMAGE TO FACILITY ,

TYPE DESCRIPTON h bJ 7 89 10 l NA l 80 PUDUCITY 8403260324 760408 gl g {DRADOCK05000 l 7 89 80 ADDITIONAL FACTORS 1a l Description of Event (continued): The high power trip is one of four redundant l 7 89 80 hl channels.

7 09 l

80 Robert Mehaffey -

NAME: PHONE. h02 426-4011 GPO 888 087 a i

LER 50-285/76-10 p !

l-Page Two 4 ATTACIIMENT 1

_ Safety Analysis The Reactor Protective System is so designed that the failure of B RpS liigh Power trip unit to trip at 104.4 percent power (which takes into account a 1.1 percent instrument error and a 1.0 percent calimetric error to insure a trip at the Technical Specification Limit of 106 5 percent) would not have prevented a reactor trip if the unit power had exceeded 106.5 percent power.

Under normal operating conditions the reactor protective system is in a two-out-of four logic configuration. The failure of B high power trip channel placed the RPS in a two-out-of-three logic. The two-out-of-three logic exceeds the minimum required for safe reactor operation as stated in Table 2-2 of the Technical Specifications. Channels A, C and D vere operational.

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LER 50-205/76-10 f',

'# 'v l Page Three NLTACli>1ET 2 Corrective Action The Bell and Howell 19-317-2X feed back limiter module was recalibrated.

Surveillance Test ST-E?S-1 Section F.2 vhich checks the variable hi Gh power trip channels was done on B channel. Proper operation of B channel was verified and then returned to service.

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LER 50-285/P3-10 Page Four Oi A'PfACHIE:iT 3 Failure Datn l l

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The drift of the high power setpoint was the first failure of this type, i

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Omaha Public Power District -

1623 HARNEY a OMAHA. NEBRASMA 68102 m TELEPHONE 530-4000 AREA CODE 402 April 28, 1976 /TT ' (gx FC-149-76 4' j'l b

Mr. E. Morris Howard 8 'C*r S U. S. Nuclear Regulatory Commission N Region IV NA 611 Ryan Plaza Drive / 74 gb

's Suite 1000 Arlington, TX 76012

Reference:

Fort Calhoun Station Unit No. 1 Docket No. 50-285-In accordance with the Fort Calhoun Station's Technical Specifica-tions, the Omaha Public Power District, as holder of facility operating license DPR 40, submits three copies of the following amended licensee event report 50-285/76-10 to satisfy the requirements of Regulatory Guide 1.16.

Sincerely, W. C. nes Section Manager Operations WCJ/WDD:rge Enclosure cc: Director, Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, DC 20555 (3)

Director, Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission l

Washington, DC 20555 (30) l Mr. L. C. Shalla SARC Chairman PRC Chairman Fort Calhoun File (2)

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