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ANP QUARTERLY PROGRESS REPORT
Studies of the corrosion of Inconel, type 316
stainless steel, Hastelloy B, and several special
alloys were continued through the use of thermal-
convection apparatus. Additional information on
the compati bi I ity of the sod ium-bery I I ium- lncone I
tern was obtained from static, whirligig, and
thermal-convection loop tests. In an effort to find
a brazing alloy that has good resistance to sodium
and to NaF-ZrF,-UF,, tests of several brazes on
type 304 stainless steel T-joints were made. Simi-
lar joints of A-nickel brazed with various alloys
were also tested in NaF-ZrF,-UF, at 1500OF and
in sodium hydroxide at 1100 and 150OoF, Addi-
tional screening tests were made of carbides of
boron, titanium, zirconium, and chromium in static
sodium, lithium, and NaF-ZrF,-UF, at 1500OF for
100-hr periods. An 80% Mg-20% Li alloy being
considered as a crew-compartment shielding material
was corrosion tested in water at various temper-
atures; the weight losses were found to be negli-
gible. The resistance of lnconel to attack by
molten rubidium was studied in a dynamic loop
apparatus. Fundamental studies are under way of
the mass transfer in liquid lead and of fused hy-
droxides as acid-base analog systems, and further
information has been obtained of the flammability
of sodium-bismuth alloys. In further chemical
studies of corrosion, information was obtained on
the effect of temperature and of chromium additions
on the corrosion of lnconel by fluoride melts with
NiF, additions,
THERMAL-CONVECTION
LOOP CORROSION STUDIES
G. M. Adamson A. Taboada
Metallurgy Division
lnconel Loop Containing UF, in
Alkali-Metal-Base Mixtures
Additional tests were made with alkali-metal-base
fluoride mixtures containing UF, and UF, in lnconel
-convection loops, but the results obtained
were not so favorable as those reported previously. ’
Considerable difficulty was encountered in making
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6. CORROSION RESEARCH
W. D. Manly G. M. Adamson
Metal lurgy Division
W. R. Grimes F. Kertesz
Materials Chemistry Division
the mixtures, in controlling the total uranium con-
tent, and in determining the ratio of UF, to UF,.
Two supposedly duplicate lnconel loops were
operated for 500 hr with the UF,-UF, mixture in
NaF-KF-LiF (11.5-42-46.5 mole %) at a hot-leg
temperature of 15OOOF (AT of -2OOOF); however,
the rough surface of one loop showed maximum
penetration to a depth of 2 mils, whereas the other
loop was attacked to a depth of 13 mils. In three
other supposedly duplicate loops operated for 1000
hr, attack to depths of 8, 13, and 13.5 mils de-
veloped. Metal l ic-appearing layers were found in
the cold legs of all these loops,
Several loops filled with NaF-KF-LiF with and
without UF, were operated to obtain comparative
data for use in evaluating the results of these
tests. The data obtained are presented in Table
6.1.
Type 316 Stainless Steel Loops Containing
UF, in Alkali-Metal-Base Mixtures
Several batches of the eutectic NaF-KF-LiF (1 1.5-
42-46.5 mole %) containing mixtures of UF, and UF,
were circulated in type 316 stainless steel loops.
However, the results obtained cannot be used for
comparative studies because the UF,-to-UF, ratios
in the fluoride mixtures were unknown and the mix-
tures were of doubtful purity. One loop plugged after
886 hr of operation at a hot-leg temperature of
1500OF; examination showed heavy, intergranular,
subsurface voids to a depth of 11.5 mils in the hot
leg and some intergranular attack in the cold leg.
Another similar loop operated its scheduled 1000
hr, but a large deposit of dendritic crystals was
found in the cold leg.
A similar loop in which all the uranium (12 wt %)
was present as UF, was operated to obtain com-
parative data. This loop plugged after 570 hr of
operation, and metallic crystals were found in the
cold leg. The hot-leg surface was very rough, and
there was penetration to a depth of 5 mils. The
‘G. M. Adomson, ANP Quar. Prog. Rep. Sept. 10. 1954,
ORNL-1771, p 96.
.
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