ML20085F558
| ML20085F558 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 11/15/1974 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20085F560 | List: |
| References | |
| RO-UE-2-75, NUDOCS 8308220444 | |
| Download: ML20085F558 (2) | |
Text
F
\\
\\
V V
I l
P
.g i,.\\6..y.. t w,
y Qh
,[
cen...i on.c.o on.c u.cnia.n evenu.a.cwwn. u.chigan em Area Cod. 61MH60
'g
'j.
'*('
~13 November 15, 1974
.s
~ J.. -
Mr. James G. Keppler, Director Re: Docket 50-255 Region III, Directorate License DPR-20 of Regulatory Operations Palisades Plant US Atomic Energy Commission UE-2-74 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
Attached is an Unusual Event Report (UE-2-7h) covering a problem with the start-up trancformer differential current protection relays. This unusual event is similar to the one reported on May 26, 1972. A preliti-nary investication of the present problem has indicated that our recent revision of the differential relay arranconent has not completely resolved the original problem.
Le investigation is continuing and we are confi-dent that an adcquate revision to the differential relaying systen can be nade and spurious operaticr. eliminated.
Adequate protection of the start-up transformer is being provided by the overcurrent protective device.
Yours very truly,
)
f
- s.., m '
'l 9
' ' ll ' < 'K). - _),c g(L..
DAB / map Ralph B. Sewell f
i Nuclear Licensing Administrator CC: Directorate of Licensing U3AEC Washington, DC I
I 0300220444 741115 11[ 3 PDR ADOCK 05000255 S
.g y p gc.;
( 2,) COPY;SENT REGION
]
O O
L l
UUUGUAL E7FMT REPORT Palisades Plant 1.
Unusual Event:
UE-2-74 2A.
Report Date: November 15, 197h 23.
Event Date: October 17, 197h 3
Facility: Palisades Plant, Covert, Michigan
[
h.
Identification of Occurrence:
Start-Up Transformer Trip During SIS Test 5
Condition Prior to Occurrence: The plant was at hot standby.
6.
Description of Event:
The quarterly safety injection system (SIS) test was in progress with the left channel part of the test having been suc-cessfully completed.
'.Then the right channel test was initiated, off-site power van lost. The diesel generators started and automatically closed to provide plant Iover.
Off-site power was restored in about one half hour.
7 Designation of Apparent Cause of Occurrence:
The installation of the current transformers associated with the differential relays appears to be the cause of the problem. This is complicated because of incom-patability probicmc associated with 3h5 kV to 2.h kV step-down situation.
8.
Analysis of Occurrcr.cc: Operation of the SIS vould have been dependent on the plant emergency diesel generators. The SIS is desi ned to oper-C ate off of the diesel generators and would have performed properly.
9 Corrective Action: The three-phase differential relays have been removed from service pending an investigation by our Relay Protection Department.
Overcurrent protection devices remain inntalled and provide adequate transformer protection.
Even so, because of the added transformer pro-tection available utilising a differential relay system, we plan to rein-stall the differential relay system when a suitable design can be achieved.
The Safety Audit and Review Board vill conduct a review of ti._
differen-tial relay system and any appropriate testing program prior to plant oper-ation (at power) with difrerential relays in service on the start-up trans former.
The SIS tect has been successfully completed with the differential relays out of service.
10.
Failure Data: This came failure occurred in May 1972 under similar con-ditions.
At that time, the differential relay system was removed from service and was not reinstalled until after it was modified in January 197h.