ML20084R788
| ML20084R788 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/06/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20084R784 | List: |
| References | |
| 870-74, AO-50-249-74-36, NUDOCS 8306150566 | |
| Download: ML20084R788 (3) | |
Text
C:mmonwealth Edison v*
pp Cm rf Ngtei P:.m. cmcaco smno s AddrcLop:y to-Pcat Off:ce Box 767 Chicago. Ilknois 60G90 BBSLtr.68f0-74 Dresden Nuc1 car Power Station p.
R. R. #1
/'-
Morrie, Illinois,60450 -
fN t
December 6, 1974 p,
c)
N$.'. L Ni.
,I}
\\
02..Gf@nd[us $;l
- 6,
'. ~
.I
..t Mr. James G. Keppler, Regicnal Director
?.
~
tf r 7,
Directorate of Regulatory Operations-Region III
's!,+4;., g p /
U. S. Atomic Enert;y Comission N"-
799 Roosevelt Road dN Glen Ellyn, Illinois 60137
SUBJECT:
REPCRT OF AP!:03;&L OCCURRE!CE PE3 SECTION 6.6.A OF THE TFM!ICAL SPECIFICATIC"S REACTOR FFED FU':P M MINI:Et FLO*.1 LINC LEAKAGE
References:
- 1) Regulatory Guide 1.16 Rev.1 Appendix A
- 2) Notification of Region III of AEC Result. tory Operations Telephone: V.r. C. Feierabend, 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on December 2, 1974 1
Telegram: Mr. J. Keppler, 0335 hours0.00388 days <br />0.0931 hours <br />5.539021e-4 weeks <br />1.274675e-4 months <br /> on December 3, 1974
- 3) Drawing Number: M-347 (SE:L)
- 4) Deviation Reports 50-237/74-41 (8-30-74), 50-237/74-46 (9-20-74),
50-249/74-33 (11-19-74), and 50-249/74-37 (12-10-74).
Report Number: 50-249/74-36 Report Date: December 6, 1974
'Occurrenee Date: December 1, 1974 Facility: Dresden Nuclear Power Station, Morris, Illinois
_ IDENTIFICATION OF OCCURRD:CE On December 1, 1974 a small leak was discovered en reactor feed pump 3A j
minirm:m flow lino 3.-3205A. This condition is an abnormal degradation of a boundary designed to contain radioactive materials as defined in Regulatory Position C.2.a(1)(c).
9 CONDITIO!!S PRIOR TO CCCifRRFlCE When the leak was discovered, the Unit, 3 reactor was shutdown.
bq) N p cv(&^
r306150566 750100 PDR ADOCK 05000249 1251
~
g PDR WY SDG
l.
Mr. James G. K 1 ler December 6, 1974
- DESCRIPPION OP OCCURTdNCE The pinhole leak on the minirmm flow line was found during a routino plant inspection at 0230 hours0.00266 days <br />0.0639 hours <br />3.80291e-4 weeks <br />8.7515e-5 months <br /> on Decc=ber 1, 1974 Since tho unit was already
(
shutdown, the i=cdiato action taken was to urito a work request to repair l
the leak.
DESIGNATION OF APPARE:T CAUSE OF OCCURRE!CE (Unusual Service Condition)
The pinholc leak on the pipe was caused by crosion of the pipo from within.
The high velocity turbulent flow in the pipo led to cavitation of the fluid which caused the crocion.
ANAIXSIS OP OCCURRFl:CE Due to.the sisc of the hole in the pipe, only minor leakage of the reactor l
feeduater was involved. If the unit had been running at normal power operation, no leakage would have occurred because the mini =um flow lines of the reactor fccd pumps are below atmospheric pressure during operation and contain water only during startups, shutdouns, and low power operations.
i i
The effect of the leak was to make it more difficult to maintain condensor vacuum, but no safety implications are made by this.
Since this type of Icak gr as only slowly due to mechanis=3 involved and the plant is frequently inspectcd. the possibility of a pipo rupture or failure, which would cause loss of vacuum and reactor feedwater leakage during shutdown or startup, is highly unlikely.
At no timo during this occurrence was the plant or public health and safety i
jeopardized.
9 CORRECTIVE ACTION The leaking pipe was isolated and the leak was repaired by building up the thickness in the area with a wcld bead and then welding a plate over the i
leak. Certified welding materials and techniques were used.
I To prevent this type of problem from occurring again, there are two modi-fications in progress, one for cach of Unita 2 and 3 - M12-2-74-161 and M12-3-74-164, to replace the one foot section of piping on the reactor feed pump mini: um flow lines uhore the cavitation has been occurring with a pipe constructed of a chro.ium-colybdenum stcol alloy. This alloy is more durable than the carbon stccl now being used.
b 1
a n.
-m s
a sg-----
swm n.
~~--,-gv-+
ra----,
w r,,--
r-------------
~
e (m
s Mr. James G. Ke)ppler o
December 6, 1974 FAILURE DATA These leaks on the nini.nm flow lines of the reactor feed pumps have been a recurring problem en both Units 2 and 3. (See Reference 5). The leaks occur in a 6"-diameter sea.mless schedule 120 class 900 heavy carbon steel of ASTM classification A106 Gr.B.
Sincerely, lh s B. B'Ste hcason Superintendent BBS:ELS:do 9
e b
_ - - - - _ _ _ _.. _.. _ _ _ - - _. - - _ - - -. - -