ML17252A916
| ML17252A916 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/04/1974 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | O'Leary J US Atomic Energy Commission (AEC) |
| References | |
| BBS Ltr. #250-74 | |
| Download: ML17252A916 (2) | |
Text
CommonwAh Edison One First NatiWP1aza, Chicago, Illinois Address Reply to: Post Office B_~ 767 Chicago, Illinois 60690
~* -
BBS Ltr.f/250*74 Dresden Nuclear Power Station R. R. #1 Mor.r.is, Illinois April 4, 1974
References:
- 1) Notification of Region III of AEC Regulatory Operations Telepho~: Mr. F. Maura, 1040 hours0.012 days <br />0.289 hours <br />0.00172 weeks <br />3.9572e-4 months <br /> on April 2, 1974 Telegram: Mr. J. Keppler, 1100 ho\\lrS on April 2,
- 1974
- 2) Dwgs: P&ID M-365
Dear Mr. O'Leary:
This letter is to report a condition relating to the operation of the uµit at about 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on April 2, 1974. *_At this time, station personnel noted a crack in the 3B Control Rod Drive Water Filter drain line.
The drain line is 3/4" diameter and is qesignated as line 3-4802B.
The leakage associated* with the.failure was minor and resulted in no significant contaminatton.
This malfunction is contrary to section-' l.A. S of the Technical Specifications, which defines an abnormal occurrence as an abnormal degradation of one of the several boundaries which are designed to contain the radioactive materials re$ulting fr()lll the fission process.
PROBLEM The problem was discovered during normal plant inspection when it was noted that there was a minor leak in the Unit 3 Control Rod Drive Water Filter 3B-302-4 drain line (3-4802B-3/4"L).
The pla~s shutdown for refueling and the CRD system was in service at the
,, ~~~ ccur-rence.
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e Mr. J. F. O'Leary April 4, 1974 The :leak-was between.the-B filter. and the.drain :valve (3-0301-128) at. the weld joining the valve to the.filter drain pipe.
The "B" filter was immediately valved out of service upon placing
- the parallel "A".filter in service.* The isolated fi'iter was drained and the release Of condensate Was stopped.
The filter WtlS OU~ of service and
. drained at 1040 :hours on April 2, 1974.
The.3B.CRD Water Filter drain line is used to drain the filter for _cleaning* or maintenance.
INVESTIGATION
.The.cracked.weld was examined by Commo~wealth Edison's Op~rational
- .Analysis Department and cletermined to be. caused by *fatigue failure.
Frequent.
operation of the draiD.valve and repeated baclq.Jashing _and changing of the filter.a* are believed to be. the causes of. the.failure *. **
- CORRECTIVE ACTIONS r,.*
~
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As indicat~d pre~i.ously, tlje f:ilter was removed from service and drained immediately.
The crack was ground out and the weld was pad welded.
Following completion. of. the-'reP,&ir'~,4 dye p_enetrant"'iest *was~ successfully
- performed; The filter:;was- 'awil.ab.le.:'for service'." at:.0800 ho'urs.. onrAprt~ 3*,.
-1974..
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. EVALUATIONS This occurrence did not jeopardize the safety -of the plant or the public and resulte'd in no significant contamination problem.
Precautions normaily in effect for the. area were sufficient.
The immediate action instituted was satisfactory and effective.
The' leak was minor, to the exte~t that it was le~king less than a bad valve packing.
The fact *that it* was _due. to a cracked weld rather than a packing resulted in its classification as an "abnormal degradation."
However, the Safety implicati(on was identical.to a '"normal" degradation which ls 'not considered to have serious safety implications.
The ;nature of the failure is such that normal maintenance
- inspections and system operational tests are adequate* to prevent or minimize
- failures of this type_ on similar equipment.
This occurrence poses no reasons for limiting future operation of Dresden Unit 3.
BBS: JR: do hens on Superin_tendent