ML17252A174
| ML17252A174 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/31/1975 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| 50-249/75-32 | |
| Download: ML17252A174 (2) | |
Text
Commo~alth Edison One First National Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 1~egulatory. Do~~e-~,,J~
~..
BBS Ltr~ #461-75 Dresden Nuclear Power Station
~. R. #1 Morris, Illinois 60450 July( 31r, 1975 i,,r-'
Mr. James G. Keppler, Regional Director Directorate of Regulatory Operation-Region III
- u. s. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois
- 60137
SUBJECT:
REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.A OF THE TECHNIC
-SPECIFICATIONS FAILURE OF RESTRAINER CLAMP BOLT KEEPER ON JEl' PUMPS
References:
- 1 ) Regula tOry Guide* 1
- 16 Rev. 1. Appendix A
- 2) Notification of Region III of u. s. Nuclear-Regljlatory Connnission Telephone: Mr. P. Johnson, O~O hours on July 22, 1975 Telegram: Mr. J. Keppler, 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> on July 22, 1975
/
- 3) Drawing Number GE Drw #(29E434 Report Numper:
50-249/7.5-32 Repo'ft Date: July 31, 1975 Occurrence Date: July 21,. 1975 Facili~: Dresden.Nuclear Power Station, IDENTIFICATION OF OCCURRENCE The ciamp belt keeper tack welds on jet pumps #6 and #17 CONDITIONS PRIOR TO OCCURRENCE Unii-3 was shut down for refueling.
DESCRIPI'ION OF OCCURRENCE At approximately 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on July 21, 1975, during restrainer Reeper lift testing of the Unit-3 jet pumps it was noted that several tack welds had -~ed on the outboard clamp bolt keepers for #6 and #17 jet pumps.
A viSual examination by underwater television had revealed no visible defects on either jet pump keeper; however, during the lift test, which asc*ertains the I'.esili~ce of keeper and weld, the welds.broke.
8376
c...,
...,... f~,-~
~. James G. Keppler July 31' 1975 DESIGNATION OF APP.ARENT CAUSE OF OCCURRENCE (Improper Installation)
The apparent. cause of ooth keeper failures is poor tack welding.
Properly made, *the welds would normally hold.the keeper securely to the jet pump restrainer. -
ANALYSIS OF OCCURRENCE.
Failure of-both inboard and outboard clamp bolt keepers could conceivably allow the clamp bolts to back out of the jet j;rump_wedge and restrainer assembly.
- A double failure of this nature occurring during reactor operation would result in increased Vibration of the jet pump and might ultimately lead to.separation of the jet pump body at the slip fitting petween the mixer and difif)).ser sections.
The_ ta.ck weld failures were induced by the;:~i:fic{~-. vibration -of the li'ft testing. The jet pumps were securely fastened.. by*m~s of the inboard cla.mP bolts, both of which were tested satisfactorily. In any <~ent, the routine daily surveillance of jet pump flow characteristics would detect any such discrepancy and the r_eactor would be shut down w:i, thin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The. loss of a jet puzp.p during operation has been analyzed as an acceptable.
condition by the Quad -Cities station; their **evaluation is applicable to Dresden. Plant personnel and the public were not endangered by this occurrence.
CO~TIVE ACTION Clamp bolt keepers-for jet pumps #6 and #17 were rewe~ded and successfully
_retested.
These jet.pumps will be inspected dbring the next major refueling-ru tage to v~rify the
- integri tY of the tack welds.
- FAILURE DATA There have been no preiriously reported failures of this nature at Dresden.
~~~~
Superintendent BBS:smp
___ F:i.J._e,.1mc _
...