ML19241B910
| ML19241B910 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/19/1979 |
| From: | Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 235B, NUDOCS 7907250326 | |
| Download: ML19241B910 (2) | |
Text
e Ve co VIRGINI A ELECTRIC AND POW ER COMP AN Y. RICHMOND, VIRGINI A 23261 July 19, 1979 Mr. James P. O'Reilly, Director Serial No. 235B Office of Inspection & Enforcement PSELC/GLP:mac: wang U. S. Nuclear Regulatory Commission Region II Docket No. 50-339 101 Marietta Stroet, Suite P 00 Atlanta, Georgia 30303 Dear "r.
O'Reilly:
On "av 4, "79, we sent an interim report to Region II concerning fa!!ura of Inside Recirculation So-ay Pumo Votors at lorth Anna. We indicated that a final reocrt would be made as soon as modifications and testing were co pleted on the moto*s.
'.ie have modified and testad al' of the motors which a*e available for testing at this time. 'fe have completed tests on A 90 tors from ou* Sur-y Power Station (2 per unit) and on ? #ron Mc-th Anna Unit 2.
All 6 of these motors cerfo-mad well uithin their allowat e bearino temoenture range during runs that were made en each motor under full 1931 conditions.
the eight o
The rema n ng motors to be modi #ied are in Mcrth Anna Ur.it 1, however, these motnes were tested successfully for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> with their existing lower notar bearings, but will be modified to he in conformance with the new desian.
The rrodification will be made to these motors during the first refueling of North Anna Unit 1.
As we described in our earlier 5 day report Aoril 11, 1977, Serial No.
255, the root of the bearino orablem acoeared to Se inadequate clearance in tha deu51e ow ball bearing which is used as a guide and a thrust baaring on the lowar end of the motor.
Since we could not obtain a double row bearing w th adequate clearanca from any hearina manuf3cture* within a short t4-'e i
- -am?, it was decided that the beiri1os must be changed to an MRC single row aagular contact solit inner ring bearing which is 3 standard stock item from "RC and has ratings exceeding the original. The first motor to be f*tted with the :1w bearing es tastad at the General Electric f acility in San Jose with good success, the motor was then shipped to Singham '4illamette Pump Company where it was tested on a pump similar to the enes used at Ncrth Anna and Surry.
The test at Bingham was also successful up to 100% load on the motor, the motor was then loadad to 108% and after one and one-half hours, rubbing as detacted where the shaft casses through the end shield.
The cause of the The enbbing acoearad to be the slinger ring on the lower end of the motor.
rino was than lovared away f*om the end shield and the 1081 load test was ocnoleted successfully.
However, after the motor had Seen returned to San Jose and disacnt'ed, ind4 cations e ra that the shaft had been rubbing the end shield itse!' tharebv creating #-ictional heating of the shaft at that point. \\
0 N
L7 uu4 O
\\
7907250 %
Mr-, James P. O'Reilly, Director 2
To eT hinate the shi't to end shield problem, the end shield coaning was increased to give a greater radial cloarance around the shaft where it passes through the en" s*ielri.
To minimiza this ine-ease, the labvrinth sealing slinge-on the lower end of the end shield was made larger in diameter, one laby*inth surface was added, olus the laby-inth clearances were made closer and the distance the lab seal sits on the shaft was made longar.
We feel that we have substantiated the cacability of the motors by test and that tha environmental qualification will be reverified with a Taoical Report by General Electric to be submitte<i no later than July 27, 1970 This reco-t will be mor? detailed cnncerning the exact dimensions, materials used, and test -esults nf the modification.
This is our final reocrt on this item.
If vou have further cuestions, clease contact this office.
/
Vseyhtrulyyours,[
/;'
y
[I/c L
Sam C 3-nwn, 1.
Senine Vica dent o -ra-St, tion n
Enr1 nee-ing and Constructinn 4
cc: "r.
Victo-Stello, Director Office of Insoection t Enforcement dr. Harold R. Denten, Director Office of 'fuclear Reactor Ragulation
@