CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II. Page: 14 of 30
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Total metal thickness losses from the pump impeller and casing(type 304 SS
and type 316 SS) after 20 years at 900*F, and 1000 hours at 1200*F, were
estimated from the available corrosion data and are given in Table 2. For
these calculations, it was assumed that the pump will operate as a hot-leg
pump at 900 F. No corrosion would be expected if the pump were locked in
the cold leg.
Remember that the estimated figures have been calculated from short-term
corrosion data, and extensive extrapolation for both time and sodium velocity
Estimates from the UKAEA Data"1'
Above approximately 10 to 15 fps, the corrosion rate was found to be inde-
pendent of the relative sodium velocity. The estimated figures, therefore,
apply throughout the velocity range of interest.
The estimated thickness loss is given as a function of oxygen level (Figure 3)
at 900 and 1200*F. The open circles represent the total corrosion after 20
years at 900*F, plus 1000 hours at 1200*F. At 15 ppm oxygen, which may be
considered to be a typical upper limit operating level, the estimated
material loss is 2 to 3 mils (Table 2).
Estimates From the G. E. Data
Corrosion rates were computed with the G.E. empirical equation for a range
of velocities for times up to 20 years.
Maximum and minimum values were computed using the reported experimental
limits with - = 0 and velocity exponents of 0.884, 0.160, and 0.2 0.
The modified equation is given as:
0.884 + 0.160 1.156 0.364
R = V Ox exp 12.845 + -23,827 2,584 + 2.26 0.66
T + 460 t.+ 1
and p = If2
The calculated values for 20 years at 900*F, plus 1000 hours at 1200*F are
given in Figures 4 and 5; typical values are given in Table 2.
Based on these data, material loss by corrosion should not represent a
problem during the pump design lifetime. High oxygen levels would only
occur during start up and cleaning, at which time temperatures are kept low.
It must be emphasized that these estimates involved extensive extrapolation
of published test data; however, they do represent the best available
estimates at this time.
These losses are for uniform corrosion and do not take into account the
possibility of intergranular attack.
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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/m1/14/: accessed March 22, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.