ML20085J972
| ML20085J972 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/04/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085J971 | List: |
| References | |
| 250-74, NUDOCS 8310190252 | |
| Download: ML20085J972 (2) | |
Text
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O C mm:nw: lth Edison 4(,9%) on:e First[ '7nal Ptara. Chicago, ilhnois h3 C
qN /,~1 Address vy to: Post Ofhce Box 767 50 249 t,/ Chicago, Ilhnois 60690 BBS Ler.0250-74 Dresden Nuclear Power Station R. R. #1 7' @ 7j</ h Morris, Illinois 60450.
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April 4, 1974 9-l i
APR8 ;N4 b ;3, t
Mr. J. F. O' Leary, Director
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f Directorate of Licensing
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.Q U. S. Atomic Energy Commission Tp%l3R T;';r M
,Cf Washington, D. C.
20545 s
SUBJECr: LICENSE DPR-25. DRESDEN NUCLEAR POWER STATION. UNIT #3, REPORT"~'
0F ABNCalfAL OCCURRENCE PER SECTION 6.6.B 0F THE TEC11NICAL SPECIFICATION.
3B CONTROL ROD DRIVE WATER FILTER DRAIN LINE.
References:
- 1) Notification of Region III of AEC Regulatory Operations Telephone: 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. Koppler,1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on April 2,1974
- 2) Dwgs: P&ID M-363
Dear Mr. O' Leary:
This letter is to report a condition relating to the optaration of the unit 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 C)ntrol Rod Drive Water Filter drain line. The drain line is 3/4" diameter and is designated as line 3-4802E.
The Icakage associated with the failure was minor and resulted in no significant contamination.
This malfunction is contrary to section 1.A.5 of ths Technical Specifications, which definns an abnormal occurrence as an abnormal degradation of one of the several boundaries which are designed to contain the radioactive materials resulting from 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 plant was shutdown for refueling and the CRD system was in service at the time of the occur-rence.
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lkr. J. F. O'Ld )
" April 4, 1974 The leak was between the B filter and the drain valve (3-0301-12B) 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 filter was drained and the release of condensate was stopped.
The filter was out of service and drained at 1040 hours0.012 days <br />0.289 hours <br />0.00172 weeks <br />3.9572e-4 months <br /> on April 2,1974.
The 3B CRD Water Filter drain line is used to drain the filter for cleaning or maintenance.
INVESTICATION The cracked weld was examined by Commonwealth Edison's Operational Analysis Department and determined to be caused by fatigue failure. Frequent operation of the drain valve and repeated backwashing and changing of the filters are believed to be the causes of the failure.
CORRECTIVE ACTIONS As indicated previously, the filter was removed from service and drained immediately. The crack was ground out and the weld was pad welded.
Following completion of the repair, a dye penetrant test was successfully performad. The filter was available for service at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on April 3, i
L9 'i4.
i EVALUATIONS This occurrence did not jeopardize the safety of the plant or the public and resulted in no significant contamination problem. Precautions notaally in effect for the area were sufficient.
The inmediate action instituted was satisfactory and effective.
The leak was minor, to the extent that it was leaking 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 implication was identical to a " normal" degradation which is not considered to have serious safety implications.
The nature of the failure is cuch 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.
Sincerely, e
/Dfkrm B. B.' Stpphenson Superintendent BBS:JR:do
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