ML19340B863

LER 80-026/03L-0:on 801030,AB-1 Matrix Relay Failed to Trip Clutch Power Supplies.Caused by Failure of Matrix Circuit to Break Contact.Relay Replaced & Applicable Surveillance Test Performed to Demonstrate Operability

ML19340B863
Person / Time
Site:	Fort Calhoun
Issue date:	10/30/1980
From:	Core M OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19340B861	List: ML19340B860 ML19340B863
References
LER-80-026-03L, LER-80-26-3L, NUDOCS 8011120476
Download: ML19340B863 (4)

Text

. _. _ . -

au m . . . . . . . . . . . . . . . . ..

(7117 ?

LICENSEE EVENT REPORT CONTROL Block: I I i i I l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) lo it 4i I9 N l ELICENSEE 1

l F l COOE Q l S l 1 l@l I4 IS 01010 l ouCENSE 10 lo 1010 In In InJSl@ld NVMBER 26 11 11 11TYPE LICENSE !1Ml@l$i 6AT l l@

64 ccN T Iolil

$$"C 60l L l@l 0 ! 5OCCKET 61

!010NbV8Em 101218 15 48 l@l1 69 10 13 10 18 10 l@lNEPCAT EV ENT 0 ATE 24 ?S 11 01 DATE al 01 30 a l n l@

EVENT DESCRIPTION ANO PACBABLE ccNSECUENC55 10 21 l During testing of the matrix logic for the reactor protective system, it was dis- I m j covered that the AB-1 matrix relay failed to trip the clutch power supplies. The  ;

io,Ai i failure resulted in only slight degradation of the system since five of the six l i,isi; logic units were properly working. The failure resulted in the loss of one of the j i a i ., i i four trip relays in ene of the six assemblies. l I

134: 1I I

icinii do 7 5 3 E CE SLSC E COMPCNENT CCCE SL'8C C'E Sb E I la!al i I I A l@ [Ej@ I A l@ l Rl El Ll Al Y I XI@ I G l@ lZ 18 19 20 l@

7 4 3 ?0 11 12 TJ SE QUENTt AL CCCUAAENCE REPCAT A Evis!CN gg a EVENTvfAM A EPCRT NC.

• CODE WPE NC.

@ s g.go ai

18 !O I l-l 10 12 !6 l 1/l 10131 lL l l-l 101 21 22 23 24 26 27 28 29 M 31 22 SLP IE VANLFA AER K N AC CN ON P NT VE *CORS h 5 B 8 8CR 9.

Li.j@luF l@

u W@ W@

10 10 10 10 l 2, 0 lYl@

.i l 2N i@ l Ni@

.2 lCl31415l@

m .,

cAuse cascRipTioN ANo ecRRecTive AcTicNs @

tiia;l The AB-1 matrix relay, a C.P. Clare Model HGZX-10ll mercury wetted relay, in the l i !i; i matrix circuit failed to break contact to trio the clutch cower sucolies. The relay i i ,,7, I was replaced with a new relay and the applicable surveillance test was performed to l

,, i3i l demonstrate operability. l It is t i s0 I

7 s 2 3I  % PCWER CTn*ER STATUS Cl3 RY OISCOVERY OE3CRIPTICN Ii i 5 l l H l@ l0 l 6 ! 5 l@l" NA l lBl@l Surveillance testina l

'JTiviry ColTENT

agLgAgg AMOUNT CF ACTIVITY LOCATICN CF AELEASE l i i s t l Z l @g Os AELEASElZ NA  !@l l l NA l

>EasCNNEt ExPCsOEs NLM8ER TYPE DESCRIPTCN l i l 71 1010101@l Il@l NA l

' PEasC~~EL m a',Es NuoEE. Escai,,0N@

NA l li h l5I 30101 o l@l12 7 11 30 7 E OE;;p pT cN NA l l i i a5 l3 i Il@l 0 7 60 nniiNi@i ig3g g g cmipTICN NA M i i i i i i i i i i i i i i :,

h of1120 '2 g, M **

1 97 N -ec,...,AReR x. Core . cNe f0242s-my

LER fio.80-026 Omaha Public Pcwer District Fort Calhoun Station Unit tio.1 Docket flo. 05000285 Attachment flo. 1 Safety Analysis l

The RPS uses a two-aut-of-four logic trip system. To automatically initiate ~ a reactor trip, two trip units in two of the four channels,

, must be in a tripped condition. If two trip units are tripped, the matrix logic system will interrupt pcwer to the CEDM clutch assemblies, thereby dropping the control rods into the core.

The AB-1 relay is used as part of a matrix ladder consisting of a set of twenty four contacts. There are six matrix ladders employed in

! the RPS which provide the required ccmbinations of two-out-of-four trip logic (i.e. A/S, A/C, A/0, B/C, B/D, C/D). If any set of contacts in the AB matrix ledder opens, relay AB-1, 2, 3 and 4 de-energi:e, opening redundant contacts to the four M relays which supply power to PS 1, 2, 3

, and 4, the clutch power supplies. Opening tne contacts from relays AB-1 o_r_ AB-2 will interrupt pcwer to PS-1 and ?S-3. Likewise, coening con-tacts from relays AB-3_o_r_ AB-4 will interrupt power to PS-2 and PS-4.

Since'the AB-2 relay, the redundant relay to AB-1 was fully Opera-tional at the time of failure of the AB-1 relay, the AB matrix was operaticnal and would have performed the required function, that is, to trip the clutch power supplies.

I, W s t

I

, - . . + - . _ . . - , . .n -_. . , - . ,, , , , - ,

- _ - - _ - . - . _ . - - - - - . _ -_=_- . -..- _ - . .

LER No.80-026

., Omaha Public Power District

- Fort Calhoun Station Unit No.1 i Docket No. 05000285 i

Attachment No. 2 Corrective Action:

J J

The AB-1 matrix relay was removed and replaced with a new relay as required by I.E. Bulletin 80-19. The matrix was then retested by per-ferming the applicable surveillance test, ST-RPS-ll.

The licensee has ordered a new style relay that will have dry con-tacts and will install the new relays during the 1981 Refueling Outage.

The licensee will continue to perform the increased surveillance as re-t quired by I.E. Bulletin 80-19.

\

a i

. x

h

~

i J

l

e LER No.80-025 Omaha Public Power District Fort Calhoun Station Unit No.1 Docket No. 05000285 Attachment No. 3 Failure Data This is the fourth reportable occurrance of its kind at Fort Calhoun Station Unit No.1. See LER's80-008, 79-009 and 79-012.

\

1