ML20031C407
| ML20031C407 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/24/1975 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| AO-7-75, NUDOCS 8110070120 | |
| Download: ML20031C407 (2) | |
Text
f_ ~:g q,r
,-~
. b
[.
.yE s.
Ic7/
1 CORSURES g
i FED 2GiM 'el Power i
i, N
E Company 2.
I; < ~ 1
- .;s Qn 9
vu u.ua 0
-['
Ed U
o.n.,. onic..: 2,2 w..
/
s.ca.on,u.cm.,...o,, 4,.. coo.,,7 7..
~
I.
February 24, 1975 V
lg >
f Division of Reactor Licensing Re:* Docket 50-155 US Nuclear Regulatory Commission License DPR-6 Washington, DC 20555 Big Rock Point Plant A0-7-75
'y.
Gentienen:
"""*~'
.?'.
e 6
Attached is an Abnormal Occurrence Report describing an event involving discovery of a defect in the Big Rock Point emergency condenser outlet pipe.
The report is incomplete at this time. A portion of the affected pipe has been removed for metallographic examination to determine the cause l
of the defect. This examination has not been completed at this writing.
^
Followind coutpletion of the metallographic examination, a supplemental re-port vil.'. be submitted.
Yours very truly, J4 Ralph B. Sevell (Signed)
RBS/ds Ralph B. Sevell Nuclear Licensing Administrator CC: JGKeppler, USNRC b&
2194 8110070120 750224 PDR ADOCK 05000155 S
?:
O O
].
(*
e l
)
>j' ABNORMAL OCCURRENCE REPORT Big Rock Point Plant
'e 1.
Report Number: _A0-7-75, Docket 50-155 2a.
Report Date: February 24, 1975 2b.
Occurrence Date: February 13, 1975 3.
Facility: Big Rock Point Plant 4.
Identification of Occurrence: Emergency condenser outlet pipe defect.
5 Conditions Prior to Occurrence: Cold shutdown for maintenance activ-ities. Emergency condenser pipe velding associated with the repair job was being inspected.
6.
Description of Occurrence: A dye penetrant inspection of the 4" out.
let pipe near the connection to the north tube bundle of the emergency condenser indicated a 30" longitudinal surface defect extending on a slight spiral configuration in the first horizontal section of pipe nearest the condenser. The r.iaximum depth of the defect as measured by ultrasonic technique is about.09" to 0.12".
It extends from one B.
weld to within a few inches of a second weld.
7 Designation of Apparent Cause of Occurrence: Preliminary evaluation indi-cates the defect to be superficial and probably due to mill fabrication.
8.
Analysis of Occurrence: This section of piping is at reactor pressure under power operation conditions and no leakage from the pipe has been detected.
i 9
Corrective Action: A section of the pipe containing the defect was removed and shipped to Consumers Power Company laboratories for metallo-graphical examination. Based on the results of the investigation conducted to date, it is concluded that an occlusion occurrc1 during the manufacturing stage. This is based on the fact that the defect under high magnification appears to have a blunt bottom. Cracks resulting from service conditions have a sharp bottom. Further, the metallographic examination has shown, to date, that the depth of the j
defect was significantly ov.arestimated. The depth span thus for in the metallographic examination is 0.17".
The final results of tNe metallographic examination vill be reported following their completion together with any additions 1 corrective action taken.
l 10.
Failure Data: None.
3
~
s a
ne,- ~.