ML20084S949
| ML20084S949 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 04/16/1974 |
| From: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20084S948 | List: |
| References | |
| NUDOCS 8306200305 | |
| Download: ML20084S949 (8) | |
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y a t 31 ABNORMAL OCCURhENCE REPORT - PALISADES PLANT:
1.
REPORT NUMBER i
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DATE - APRIL 15, 1974 8306200305 740510 3.
OCCURRENCE DATE - APRIL 7, 1974
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d IDENTIFICATION OF OCCURRENCE - PLEXIGLASS DROPPED INTO
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O REACTOR CAVITY CONDITIONS PRIOR. TO OCCURRENCE - REFUELING IN PROGRESS 6.
7.
DESCRIPTION OF OCCURRENCE WHILE INSERTING FUEL ASSEMBLIES INTO THE REACTOR, THE UNDERWATER LIGHTS ARE NORMALLY ADJUSTED TO BETTER ILLUMINATE THE FIELD OF VIEW ui THE REFUELING MACHINE TV CAMERA.
ONE OF THE LIGHTS WHICH IS USED IS POSITIONED THRU A VIEWING PORT ON THE DECK OF THE REFUELING MACHINE TROLLEY.
THE VIEWING PORT HAS STANDARD 3 X 1 DECK GRATING WHICH RESTS OVER A PIECE OF PLEXIGLASS.
THE GRATING PROVIDES SUP-l PORT FOR PERSONNEL STANDING IN THE VICINITY AND THE PLEXIGLASS IS PROVIDED TO PREVENT OBJECTS FROM FALLING THRU THE GRATING INTO THE SF-1201 MCTOR CAVITY.
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O DURING THE INSERTION OF THE UNDERWATER LIGHT, A PIECE OF THE PLEXI-GLASS - ESTIMATED TO BE THREE INCHES WIDE AND EIGHTEEN INCHES LONG AND 1/16 INCH THICK; BROKE OFF THE LARGE PIECE AND FELL INTO THE HEACTOR CAVITY.
A TH080lEH SEARCH OF THE REACTOR VESSEL, REACTOR GAVI!Y, AND TILT PIT REVEALED THAT THE PLEXIGLASS PIECE HAD COME TO REST ON THE TOP OF THE CORE SHROUD FORMER PLATE AT THE NORTHEAST SIDE OF THE REACTOR.
WHILE ATTEMPTING TO RETRIEVE THE PLEXIGLASS IT SUBSEQUENTLY FELL THRU THE ANNULUS BETWEEN THE SHROUD FORMER PLATE AND THE CORE SUPPORT BARREL.
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DESIGNATION OF APPARENT CAUSE OF THE OCCURRENCE - INADEQUATE DESIGN OF THE VIEWING PORT l
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DURING THE INSERTION OF THE UNDERVATER LIGHT, A PIECE OF THE PLEXI-GLASS - ESTIMATED TO BE THREE INCHES WIDE AND EIGHTEEN INCHES LONG AND 1/16 INCH THICK; BROKE OFF THE LARGE PIECE AND FELL INTO THE nEACTOR CAVITY.
A TH0H0lEH SEARCH OF THE REACTOR VESSEL, REACTOR I
GnVITY, AND TILT PIT REVEALED THAT THE PLEXIGLASS PIECE HAD COME TO REST ON THE TOP OF THE CORE SHROUD FORMER PLATE AT THE NORTHEAST SIDE OF THE REACTOR.
WHILE ATTEMPTING TO RETRIEVE THE PLEXIGLASS l
IT SUBSEQUENTLY FELL THRU THE ANNULUS BETWEEN THE SHROUD FORMER PLATE AND THE CORE SUPPORT BARREL.
8.
DESIGNATION OF APPARENT CAUSE OF THE OCCURRENCE - INADEQUATE DESIGN OF THE VIEWING PORT sF.1201 (R$49)
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3.
ANALYSIS OF OCCURRENCE:
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A.
THE POSITION TO WHICH THE PLEXIGLASS FELL MAKES IT IR-RETRIEVABLE.
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BELOW THE TOP FORMER PLATE THERE ARE SEVEN ADDITIONAL FORM-B.
ER S, UPON WHICH THE PLEXIGLASS MAY HAVE COME TO REST.
IF IT CONTINUED TO FALL, IT MAY HAVE REACHED THE CORE SUPPORT PLATE UEHIND THE CORE SHROUD.
IT COULD NOT HAVE FALLEN ANY FARTHER l
SINCE THE LARGEST HOLES IN THE CORE SUPPORT PLATE BEHIND THE SHROUD ARE 3/4 INCH IN DIAMETER.
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C.
THE MAXIMUM FLOW RATE AT ANY POSITION THAT IT FELL IS ES-
' " " IIMATED TO BE 6 FT/SEC - IN THE ANNULUS BETWEEN THE SHROUD l
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FORMER AND THE CORE BARREL.
ALTHOLGH THIS VELOCITY IS PROBABLY O
SUFFICIENT TO MOVE THE PIECE OF PLEXIGLASS, IT IS HIG HLY IM-PROBABLE THAT IT WOULD STOP IN A POSITION WHERE THE VELOCITY WAS THAT HIGH AND THEREFORE IT IS MOST LIKELY TRAPPED INSIDE THE SHROUD.
D.
PRELIMINARY TESTS INDICATE THAT AT 550 DEGREES F THE PLEXI-GLASS IS VERY SOFT AND PLIABLE AND IT IS EXPECTED THAT IT WILL BE FLUID BEF0HE THE MINIMUM TEMPERATURE FOR CRITICAL 525 DE-GREES F IS REACHED.
AUTOCLAVE TESTS WILL BE PERFORMED BE CE TO DETERMINE ACTUAL CONDITIONS AT 532 DEGREES F AND 1800 PSIA.
E.
IF THE PLEXIGLASS WERE TO GET INTO THE FLOW STREAM IT MAY
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UNTIL IT BECAME FLUID ENOWH TO FLOW THRU THE TUBES.
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I BECAME FLUID ENOWH TO FLOW THRU THE TUBES IT WOULD THEN PASS THRU THE PRIMARY COOLANT PUMPS, DOWN THE OUTSIDE OF THE CORE SUPPORT BARREL AND, IF IT MADE IT AROUND THE TURN, IT WOULD EVENTUALLY REACH THE FUEL ASSEMBLIES, BUT DUE TO THE TORTUGUS PATH IT WOULD BE VERY STRINGY AND THEREFORE WELL DISPERSED.
F.
PLEXIGLASS IS A METHYL METHACRYLIATIC HYDROCARBON '.'HICH IS COMPOSED OF ONLY HYDROGEN, CARBON AND OXYGEN.
THE HYDROCARBON WILL DECOMPOSE DUE TO TEMFERATURE.
WE HAVE SELECTED CE TO PERFORM AUTOCLAVE TEST TO VERIFY DECOMPOSITION AND ALSO TO RUN CORROSION TEST.
THIS DATA WILL BE AVAILABLE LATER THIS WEEX AND THE RESULTS WILL BE FORWARDED TO YOU.
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A SCREEN WILL BE USED TO REPLACE THE PLEXIGLASS SO THAT IT IS NOT LIKELY TO FALL OFF, AND EVEN IF IT DOES FALL OFF IT WILL BE EASIER TO RETRIEVE.
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A.
RO Inspection Report No.
Transmittal Date Distribution:
Distribution:
R0 Chief, FS&EB R0 Chief, FS&EB RO:HQ (5)
RO:HQ (4)
DR Central Files L:D/D for Fuels & Materials M
Regulatory standards (3)
DR Central Files i
Licensing (13)
7 B.
RO Inquiry Report No.
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k Transmittal Date
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Distribution:
Distribution:
I RO Chief, FS&EB R0 Chief, FS&EB RO:HQ (5)
RO:HQ DR Central Files DR Central Files
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Regulatory Standards (3)
RO Files 4-Licensing (13)
RO Files C.
Incident Notification From: Consumers Power Co. Docket No. 50-255 5_
(Licensee & Docket No. (or License No.)
Transmittal Date April 23, 1974 Distribution:
Distribution:
_f RO. Chief, F.S&EB R0 Chief, FS&EB RO:HQ (4)
RO:HQ (4)
P Licensing (4)
L:D/D for Fuels & Materials DR Central Files DR Central Files RO Files RO Files i
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