ML19210A154
| ML19210A154 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/13/1976 |
| From: | Arnold R METROPOLITAN EDISON CO. |
| To: | |
| References | |
| GQL-0207, GQL-207, NUDOCS 7910240879 | |
| Download: ML19210A154 (4) | |
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DESCHiPTION ENCLCSURE LTR, RO 90-289/76-5/IT ON 2-3-76.......
LICENSEE EVENT REPORT CONCERNING INOPERABLE AUTO-ACTUATION LOGIC RELAY IN REACTOR COOLANT CHANNEL "3B".
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,g GQL 0207 Director of Nuclear Reactor Regulation
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p@li U. S. Nuclear Regulatory Cer=irsion ge, Washington, D. C.
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DOCKET NO. 50-289 CPERATING LICENSE NO. DPR-50 g
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Dear Sir:
In accordance with the Technical Specifications of cur Three Mile Island Nuclear Station Unit 1 (DII-1), we are reporting the folleving reportable occurrence:
(1)
Report Number: ER 76-5/IT (2)
Report Date: February 13, 1976 (2b) Event Date: February 3, 1976 (3)
Facility: Three Mile Island Nuclear Station Unit 1 (h)
Identification of Event:
Title:
Incperable Auto-Actuatien Lcgic Relay in Reactor Coolant Channel "33".
Type:
An abnor=al occurrence as defined by the Technical Specifications, paragraph 1.8, in that an incperable auto-actuatien logic relay threatened to cause an Engineered Safeguard feature er system to be in-capable of performing its intended functicns.
(5)
Cceditions Prior to Event:
Power: Core: 1005 Elec. 852 MWe (Gross) 6 RC Flow: 139x10 lbs./hr.
RC Pressure: 2162 psig RC Te=pi 580 F Pr:r Level: 2Li inches Pr:r Te=p.: 655 F 1515 1490 076
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To: Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Cen=ission
? age 2 Februatr 13,1976 GQL 0207 DCCKET NO. 50-289 OPERATING LICENSE NO. DPR-50 (6) Description of Event:
At 0110 hours0.00127 days <br />0.0306 hours <br />1.818783e-4 weeks <br />4.1855e-5 months <br /> on February 3, 1976, while performing Surveillance Procedure (SP) 1303 h l3 (Reactor Building i
Emergency Cooling and Isolation System Analog Channels) an auto-actuation relay (62x3/RC33) in Reactor Ccolant Channel "33" failed to go to its ES position upcn receipt of an ES trip signal. This relay is part of the two (2) out of three (3) auto-logic for Actuaticn 3, Block k ec=ponents. It failed again when Channel RC33 was reset and tripped once scre. The 62x3/RC?B relay then vent to its ES position when its ar=ature was tapped.
I==ediately, the redundant Actuation "A" channels relays were tested and verificd cperable.
(7) Designation of Apparent Cause of Event:
The cause of this event has been determined to be material in that slight techanical binding of the armature and contact linkage appeared to be the cause for the relay failure. Disasse=bly of the relay revealed sc=e metal chips which =ay have caused, or contributed to,the relay binding.
(8) Analysis of Event:
It has been deter =ined that this event did not ccns titute a threat to the health and safety of the public in that:
a.
The relay legic for redundant Actuatien "A" Channels was fully operational.
b.
One (1) Actuation is sufficient to actuate the Engineered Safeguard cc=penents required for operation in the event of a loss of coolant accident.
c.
Actuation 3 Channels for Load 31ceks 1, 2 and 3 vere fully operational and the respective ec=pcnents vould have actuated in the event of a less of coolant accident.
Althcugh the failure of 62x3/RC33 placed Lead Block k cc=ponents in Actuatien 3 in a two (2) out of two(2) logic =cde instead of the nor=al two (2) cut of three (3)
Icgic, these ec=ponents vculd have still operated in the event of an ES signal.
1490 077
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To: Director cf Nuclear Reactor Regulation U. S. Nuclear Regulatory Cer=ission Page 3 February 13, 1976 GQL 0207 DCCKET NO. 50-289 OPERATING LICENSE NO. DPR-50 (9) Corrective Action:
In addition to the i= mediate action described above, the faulty 62x3/RC3B relay vac replaced with an identical spare.
The relay and its associated circuitry were verified operable by functional tests, including actuation of affected cctponents.
The monthly surveillance test (SP 1303 h.13) is sufficient to detect any future relay problems in this system. No further long tern corrective action is required.
(10) Failure Data:
Manufacturer:
The Clark Jentroller Co.
Type:
PM Relay Cat. No.:
5U12-11 10 AMP, 600VAC Bulletin T305 Coil No.:
TB130-1 (120V 60hz)
Similar Events: None Sincerely, I"
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R. C.f RNCLD A
VICE PRESIDENT RCA:JMC:rk 1490 078