05000346/LER-1980-064-03, /03L-1:on 800822,station Experienced Loss of Essential Instrument Ac Panel Y2.Caused by Failure of YV-2 Inverter Input Fuse & Other Undetermined Causes.Failed Fuse Replaced: Difference between revisions

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{{Adams
#REDIRECT [[05000346/LER-1980-064-03, /03L-0:on 800822,station Experienced Loss of Essential Instrument Ac Panel Y2.Caused by Failure of YV-2 Inverter Output Fuse.No Cause Determined for Fuse Failure. Failed Fuse Replaced]]
| number = ML19345D330
| issue date = 09/18/1980
| title = /03L-1:on 800822,station Experienced Loss of Essential Instrument Ac Panel Y2.Caused by Failure of YV-2 Inverter Input Fuse & Other Undetermined Causes.Failed Fuse Replaced
| author name = Isley T
| author affiliation = TOLEDO EDISON CO.
| addressee name =
| addressee affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
| docket = 05000346
| license number =
| contact person =
| document report number = LER-80-064-03L, LER-80-64-3L, NUDOCS 8012120512
| package number = ML19345D332
| document type = LICENSEE EVENT REPORT (SEE ALSO AO RO), TEXT-SAFETY REPORT
| page count = 3
}}
{{LER
| Title = /03L-1:on 800822,station Experienced Loss of Essential Instrument Ac Panel Y2.Caused by Failure of YV-2 Inverter Input Fuse & Other Undetermined Causes.Failed Fuse Replaced
| Plant =
| Reporting criterion =
| Power level =
| Mode =
| Docket = 05000346
| LER year = 1980
| LER number = 64
| LER revision = 3
| Event date =
| Report date =
| ENS =
| abstract =
}}
 
=text=
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CON'T 6d b3 EV ENT D ATE 74 7'J REPORT D ATE 80 6d 61 OOCAETNyYdER I
d EVENT DESCRIP'. TON AND PROB A6LE CCNSECUENCES h IO f 2l I(SP-33-SO-70 On 8/22/80 at 1446 hours and on 8/23/80 at 0922 hours, the station ex-l lperienced s. loss of Essential Instrument AC 'anel Y2.
The result was the de-energiza-l 93,3, System l
, o,,,, l tion of Safety Features Actuation System (SFAS) Channel 2, Reactor Protection
,.l' g(RPS) Channel 2 and Steam and Feedwater Rupture Control System (SFRCS) Channel 2 wh
,g,3, This placed the
,3,e,, caused the containment radiation string for SFAS Channel 2 to fail.
There was no danger to the public or station j
i o I 7 I I station in violation of T.S. 3.3.2.1.
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radiation monitoring were operable.l g ersOnnel. The other three channels of containment so p
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==CAUSE==
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Q 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACflONS q
1 101 IThe cause was the f ailure of the YV-2 inverter input fus5. however. the exact caitse of!
k Ii li l Ithe ftise failure has not been determined.
The first ew.it was corrected under Ma in teT4-Iii?Ii ace Work Order 80-3049 by replacing the failed fuse.
SFAS Channel 2 was re-energized I g
I1 13 I lat 1645 heurs on 8/22/80. The second event was corrected similarily under MUO 80-3051 l t
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m land at 1346 hours on 8/23/80 SFAS Channel 2 was again re-energized.
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==DESCRIPTION==
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TOLEDO EDISON COMPAhT DAV' -BEGSE NUCLEAR POWER STATION UNIT ONE sui r cAESTAL INFORMATION FOR LER NP-33-80-74 0 ATE OF EVENT:
.,st 22, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of Essential Instrument AC Panel Y2.
The unit was in Mode 5 with Power (WT) = 0 and Conditions Pric r to Occurrence:
Load (Gross MWE) = 0.
Description of Occurrence: On August 22, 1980 at 1446 hours, the station experienced a loss of Essential Instrument AC Panel Y2.
This resulted in the de-energization of Safety Features Actuation System (SFAS) Channel 2, Reactor Protection System (RPS)
This Channel 2, and Steam and Feedwater Rupture Control System (SFRCS) Channel 2.
ais also failed caused the containment radiation string for SFAS Channel 2 to fail.
Since BWST Chan-the Channel 2 Borated Water Storage Tank (BWST) low level bistable.
nel 4 vas already in the tripped condition for maintenance, the station expe rienced an Incident Level 5 actuation on actuation Channel 2.
The loss of RPS Channel 2 also caused the loss of Source. Range Indication NI-1.
NI-2 was operable at the time.
The loss of the containment radiatior string for SFAS Ch'annel 2 is reportable per Technical Specific _ ton 3.3.2.1 which _ -m: ires all four channels of containment radf a-tion to be operable in all modes.
The action statement, which requires the failed channel to be placed in the tripped condition, was met.
=
h The Incident Level 5 actuation is only required to be operable in Modes 1, 2, 3, and 4.
[
Being in Mode 5, it is not reportable.
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Again at 0922 hours on August 23, 1980, the station repeated its loss of Essential Instrument AC Panel Y2.
The result was a de-energization of SFAS CManel 2, RPS Chan-l nel 2, and SFRCS Channel 2.
This caused the loss of the SFAS Channel 2 centainment the failure of the BWST low level bistable for Channel 2 and with b
radiation string, the BWST Channel 4 already tripped, the station experienced an Incident Level 5 actua-tion on actuation Channel 2.
The same action statement was entered as with the first occurrence.
Designation of Apparent Cause of Occurrence: The loss of Y2 in each event was due to 1
a failed YV-2 inverter input fuse. The exact cause of the. fuse failure has not been And There was facility change request work ongoing in the cabinet room.
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pinpointed.
a failure in the SFAS Channel 2, RFS Channel 2, or SFRCS Channel 2 cabinet would have This fed back to the YV-2 fuse before the fuse in the individual cabinet could fail.
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is because YV-2 is designed to fast fail to protect the inverter.
It appears that the failure occurred when wires were being connected in these cabinets. Apparently, leads touched some wrong terminals and cauued a short that caused the YV-2 failure.
g LER #80-064 L
 
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TOLEDO EDISON COMPANY I
DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORM TION FOR LER NP-33-80-74 Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel.
The other three channels of containment radiation monitor-
:- ing were operable. The SFAS Incident Level 5 actuation did not cause any water to reach the emergency sump as the Emergency Sump Isolation Valves DH9A and DH9B were closed and power removed.
t
 
==Corrective Action==
The first event was corrected under Maintenance Work Order 80-3049 by replacing the failed fuse.
SFAS Channel 2 was re-energized at 1645 hours on August 22, 1980. The second event was corrected under Nbintenance Work Order 80-3051 by again replacing the failed fuse. At 1346 hours on August 23, 1980,-SFAS 7
Channel 2 again was re-energized, which removed the station from the action' statement of Technical Specification 3.3.2.1.
Previous similar events were reported in NP-33-79-13 (79-009) and Failure Data:
NP-33-80-70 (80-056).
LER #80-064 l
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Latest revision as of 14:54, 25 December 2024