CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II. Page: 13 of 30
This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
There is some supporting evidence for this change in the rate
controlling process from other systems. Kassner studied the
dissolution of Type 304 stainless steel in a Bi 42% Sn eutectic alloy
by means of a rotating disc. At low angular velocities, the corro-
sion rate was velocity dependent, but became independent of velocity
at higher angular velocities, indicating a transition to a surface
reaction controlled process.
G. E. Data
Analysis of G.E. corrosion data indicated a velocity dependence as
given in equation (2) throughout the velocity range investigated.
This indicates that mass transfer through the boundary layer might be
the controlling factor at high velocities as well as low. Recently,
however, it has been reported that this velocity dependence is
incorrect and that the velocity exponent is 0.2 rather than 0.884.
Continuous mass transfer will occur in a flowing sodium system as long
as a temperature difference exists between various parts of the system.
Generally, material will be removed from the hot regions and deposited
in the cold regions. This process is complicated somewhat by 'the
downstream effect', and material in the hot leg will show varying weight
losses with position in the hot leg.
As expected, corrosion rates increase with increasing temperature. The
effect of oxygen however, is unexpected. As can be seen, oxygen levels
must be kept to a minimum for minimum corrosion rates.
The effect of velocity at velocities above 15 fps is apparently marginal.
The UKAEA data, in fact, shows a velocity independent of corrosion rate.
The more recent analysis of the G.E. data has only a slight velocity
dependence of V0-2.
Carbon mass transfer will only be referred to briefly here, since problems
should be minimal in an all-stainless steel loop.
If both austenitic and ferritic materials are present in the same loop,
carbon will transfer from the ferritic to the austenitic alloy, resulting in
carburization of the austenitic steel and possible degradation of mechanical
properties. Carburization was observed in both programs in bi-metallic
loops. In all-stainless steel loops, however, carbon transfer was insigni-
Here’s what’s next.
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
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/m1/13/: accessed March 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.