05000285/LER-1982-010

LER 82-010/03L-0:on 820430,during Routine Operations,Reactor Protection Sys a Channel Trip Unit 3 (Reactor Coolant Flow) Setpoints Drifted Out of Spec in Nonconservative Direction. Caused by Faulty Negative 15-volt Power Supply

ML20053D914
Person / Time
Site:	Fort Calhoun
Issue date:	05/03/1982
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20053D910	List: 05000285/LER-1982-010, Forwards LER 82-010/03L-0
References
LER-82-010-03L, LER-82-10-3L, NUDOCS 8206070435
Download: ML20053D914 (4)

LER-2082-010,

Event date:
Report date:
2852082010R00 - NRC Website

text

NRC F oRM y U. S. NUCLEAR RE2 ULATO7.Y COMMISSIOiJ (7 77)

LICENSEE EVENT REPORT CONTROL BLOC.<: l 1

l l l l l lh 6

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

?

0 1 8 9 lNlE l F l C l S l 141 l@l LICENSEE CODE IS 0 l 0 l 0 l 0LICENSE l 0 l 0NUMBER l 0 l 0 l 0 l 0 l 025 l@l26 4 l 1 l 1 l 1 l 1 l@l57 CAT LICENSE TYPE Jo l

b8 l@

CON'T IOlil 7 8 Z "C l60' l@l 61015 l 0DOCKET l 0 l NUMBER 0 l 2 l 8 l 568l@l69 0 l 413 l 0 l 8 l 21@l EVENT DATE 74 75 01510 l 3181280l@

REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l o l 2 l l During routine operations at approximately 99% power, the Reactor Protective System I g o ,3 ; ;"A" channel-trip unit No. 3 (Reactor Coolant Flow) setpoints had drif ted out of speci-l lol4llficiation in the nonconservative direction. Maintenance Order 14828 was written to l

[og.,;l Investigate the drift. The R.P.S. was immediately placed in a two-out-of-three logic l

,10161 l trip mode (fOr Reactor Coolant flow c:annels Oniv). Technical Specification 1.3(2) and o , l2.15 apply. l

~

101811 l E CODE SUBCO E COMPONENT CODE SUSCOD'E SU E 7

O 9 8 9 ll lAl@ J @ W @ lllNlSlTlRlUlh W @ W @

10 11 12 13 18 19 20

,,, SEQUE NTI AL OCCURRENCE REPORT REVISION LE R/RO EVENT YEAR REPORT NO. CODE TYPE NO.

@y R l8l2l l-l l 0l 1l 0l {f__j l0l3l [,L j ( ,) [0_j 21 22 73 24 26 27 28 29 30 31 32 T If N AC O ON PL NT M T HOURS S8 IT D FOR 8. SUPPL MANUFAC RER lA JJ lgl34Zlg ]g 35

{@

36 l 0l 0l 0l 0l 3s 40 W@ lNl@ lNl@ lPl3l114l@

41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i l 0 l lAf ter troubleshooting, it was discovered that the setpoints had drif ted out of soeci- l 3 i l fication due to d faulty negative 15 volt Power supply (which feeds tne trip unit). _

I g , ; 2 g lThe power supply was replaced, the unit was calibrateO per calibration procedure CP- l 3 3 lRPS-3 and proper operation of the trip unit verified per applicable surveillance test.I i 4 lThe unit was returned to service in less than 8 hrs. from initiation of the problem. l 7 8 9 80 ST S  % POWE R OTHER STATUS IS O Y DISCOVERY DESCRIPTION l i l s l [E,_J@ l 0 l 9 l 9 l@l NA l [A_J@l Operator Observation l A TlVITY CO TEt. ;

RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE i r2 [Z_] @ [Z,,J @l NA l l NA _l 7 8 9 10 13 44 45 80 PERSONNEL EXPOSURES NUUS E R TYPE DESCRIPTION i i l010 l0 l@y@l NA l PERSONNELINJU IES NUMBER DESCRIPi10N i a NA l

.7 .a 9 l 0 l 0 l 0 l@li2 si 80 LOS$ OF OR DAMAGE TO FACILITY TYPE DESCRIPTION 9 NA l

(_Z_J@l s0 7 a e 30 Puaucuv 8206070435 820528 NRC USE ONLY

• PDR ADOCK 05000285 .

2 O usuto@DESca

[N_J l S PDR l llllllll1IlIli 7 8 9 to 68 69 80

! ._ _ . m.NAME oF PREPARER an@ M1er POE  ;*

O lek No. 82J010 Omaha Public Power District Fort Calhoun Station Unit No. 1 4

Docket No. 05000285 Attachment No. 1 Safety Analysis The Fort Calhoun Station Reactor Protective System (RPS) is de-signed such that no single failure can prevent the RPS instrumentation and equipment from performing its design safety function. During the inoperability of the RPS channel "A", trip unit No. 3 " Reactor Coolant Flow", the three remaining reactor coolant flow trip channels (B, C, and D).were operable and functioning at the appropriate setpoints. Since channel "A" was immediately placed in the bypass condition,.the RC flow-channels were then operable in a two-out-of-three trip _ logic until the faulty power supply could be replaced and the subject trip unit re-calibrated.

The trip setpoints for the RC flow channels of the RPS are verified monthly per Surveillance Test ST-RPS-3, F.2. This monthly surveillance test ensures the RC flow pretrip and trip setpoints are properly function-ing and will detect setpoint drifting or system malfunction.

• • • M"A.a > -m me # Q4 4 , fr. 6 -+ %p e p; dm A%

• m e w- % ._eM M**

• a d Wh W .4 ,M M , ,W J w %daus a 4'kF L 4W i' 9 '. 414' We i AIW-

s LER No.82-010 Omaha Public Power District Fort Calhoun Station Unit No. 1 Docket No. 05000285 Attachment No. 2 Corrective Action Upon inspection of the trip unit and associated circuitry, it was discovered that the RPS "A" channel trip unit No. 3 had a faulty negative 15 volt power supply. The defective trip unit was-immediately placed in

" bypass". The power supply was replaced with a spare. The trip unit was recalibrated per calibration procedure CP-RPS-3, satisfactorily tested for operation via applicable portions of surveillance test ST-RPS-3, F.2 and returned to operation. This repair process took less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to complete. .

..-.w -

...--+++.mm % ~u - aan-- .,= A<~~ e . u+,

LER No.82-010 omaha Public Power District Fort Calhoun Station Unit No. 1 Docket No. 05000285 Attachment No. 3 Failure Data This is the third reportable failure of a Reactor Coolant Flow Channel. The first and second failures were reported per LER's 78-20 and 80-12, respectively.

w.s , ..+ . . , , . . ,s a s ,e wwa s - .a . a u ,a2 n . .4 ~, *~