ML17252A827
| ML17252A827 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/14/1975 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| BBS 99-75 50-249/75-5 | |
| Download: ML17252A827 (2) | |
Text
CommonwealtlAison One First National f>iW' Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 BBS Ltr. #99-.75 Mr. James G. Keppler, *Regional Director Directorate of Regulatory Operation-Region.III
- u. s. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 e
B~gulatory Docket fjl@.
- I.
--* ** ~.* -*** *._ ** -::~' *:_:]
SUBJECT:
REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.A OF THE TECHNICAL SPECIFICATION REACTOR FEED PUMP 3C PUMP CASING VENT LINE1'.WELD LEAK
References:
Regulatory Guide 1.16 Rev 1 Ap~endi~*A
\\1:
~
- 1)
- 2) Notification of Region III of U.S. Nuclear Regulatory Commission Telephone:
P. Johnson, 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> dh Febrµary 10, 1975 Telegram: J. Keppler:;.and J. 6 'Leary\\, 1608 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.11844e-4 months <br /> on February 10, 1975
. I,
- 3)
Drawµig Number:
P & ID M-349 Report Number:
50-249/1975-5 Report Date:. February 14, 1975 Occurrence Date:
February 8, 1975'-'
mDENTIFICATION OF OCCURRENCE A crack in one of the -two vent lines was found ll.l t:hei! nipple at the top of the weld where the nipple enters the pump casirig. This condit1on is an abnormal degradation of a boundary designed to con1?ain radioact~ve materia~s as defined in Regulatory Position C.2.A (1)(C).
CONDITIONS PRIOR TO OCCURRENCE
- i At the time the crack was found Unit 3 was operating at a thermal power of 1249 MW and a load of 403MWe.
The 3A and 3C Reactor*Feed:Pumps were in service.
DESCRIPTION OF OCCURRENCE At 1812 hours0.021 days <br />0.503 hours <br />0.003 weeks <br />6.89466e-4 months <br /> on February 8, 1975 a steam leak was detected at the 3C Reactor Feed Pump.
When the insulation was removed from the pump the next morning, water was -found spraying from one of~1'the vent lines a~ a weld connection at the pump casing. The electrical load was reduced by 30 MWe and the 3C Reactor
- 1 Feed Pump was shutdown and isolated.
FEB 1 8 1975 1991
- __~James G. Keppler *
-2;_
bruary 14, 1975 A dye penetrant examination* was* per.formed revealing. a crack about 3/4 inch long over 1/3 of the circumference of :the pipe-ntpple weld at the top of the weld where the nipple enters the pump casing.
DESIGNATION OF APPARENT CAUSE OF OCCURRENCE (Equipment Failure)
The crack was apparently caused by failure to properly preheat the weld area during initial construction.
ANALYSIS OF OCCURRENCE Due to the size of the crack, only minor leakage of :reactor feedwater was involved.
Since the feed pump coUld be quickly isolated from the reactor, the loss of a significant amount of reactor water was highly unlik;~ly.
At no time was plant and public health and safety jeopardized. All leakage was contained within the plant.
CORRECTIVE ACTION The cracked nipple and connected "L" joint were removed and replaced in kind.
Certified material (ASTM A335 Group F-5 Sch. 80) and a certified welder were used.
309 Stainless~steel was used to weld the nipple to the casing, and the pipe was preheated to 300 °F.
FAILURE DATA Only one other failure of this type has occurred previously. This also occurred on the :£, Reactor Feed Pump on the other vent line. :None of the other five feed pumps (including Unit 2's pumps) have experienced th{s type of problem.
BBS:ELS:smp File/AEC tephenson Superintendent