CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II. Page: 27 of 30
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Previous Operating Experience with Bearing Materials
The Rapsodie191, Hallam, Fermi, and EBR-II Reactors used Colmonoy-
faced sleeves and shafts in the hydrostatic sodium lubricated pumps.
Bearing operation of the Hallam, Fermi, and EBR-II pumps has been satis-
factory; but, all operations have been at temperatures below 1000*F. A
seizure occurred on one of the Rapsodie intermediate pumps before attaining
an operating temperature of 1022*F. The cause of the seizure was not
determined. A Rapsodie primary pump seizure occurred sometime later and
its probable cause was lack of wear resistance in the bearing material.
The pump's operating temperature is now limited to 842*F. The same report
states that all previous prototype bearings were made of Stellite, but for
the Rapsodie pumps, a change to Colmonoy was made. The use of the proven
material, Stellite, might have eliminated the seizures.
Stellite 6 bearing material has been successfully used in the PFR pump [21
52elopment program at temperatures of about 750*F for about 7000 hours
This included 1800 hours at 10% power, during which significant wear
would be expected. Examination of the pump at that time revealed no major
It is impossible to give any estimate of bearing lifetime on the basis of
existing data. Fortunately, however, both bear and corrosion results
reported for Stellites to date are encouraging and indicate that the low-
operating temperature and oxygen level will aid the reduction of wear and
corrosion of the bearing materials.
Conclusions and Recommendations
Because of the pump operating conditions, 900*F, 15 ppm 02, no significant
corrosion problems are envisaged for the pump constructional materials.
At these temperatures, the estimated corrosion thickness losses are extremely
low and not likely to present any problems. There is a possibility of
thickness loss by erosion in regions that experience a high relative sodium
velocity, e.g., the impeller tip, (80 fps). No estimate of the extent of
such damage can be given; but, a program is now being designed to determine
As far as can be ascertained from available mechanical property data, at
this temperature and oxygen level, mechanical properties should remain
unchanged from the available in-air or inert atmosphere properties. While
no problems are expected in this area, there is an obvious need for mechanical
property data in sodium over the entire temperature range experienced by plant
Data on Stellites indicate that, as far as corrosion and wear are concerned,
they are the best choice and should perform adequately. However, the
existing wear data are strictly comparative, and before estimates can be
made of wear during operation, testing must be carried out under simulated
startup and low-load conditions.
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Thomas, K.C. & Shiels, S. CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II., report, October 31, 1970; Madison, Pennsylvania. (https://digital.library.unt.edu/ark:/67531/metadc1034653/m1/27/: accessed March 21, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.