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ANP PROJECT PROGRESS REPORT
and 5%, respectively. As may be seen in Table
3.1.5, the chromium content of the fuel mixture
circulated in the Hastelloy X loop was much higher
than that of the fuel mixture circulated in the
Hastelloy W loop. This reflects the greater
tendency toward chromium removal and the
resultant void formation in alloys with high
chromium contents, such as Hastelloy X.
FLUORIDE FUEL MIXTURES IN MONEL
THE RMAL-CONV ECT IO N LOOP S
J. H. DeVan
Three monel thermal-convection loops, 806,
808, and 809, completed 500, 545, and 1027 hr of
operation, respectively, with the fuel mixture
Fig. 3.1.5. Metallic Crystals and Layer De-
posited in Cold Leg of Hastelloy X Thermal-
Convection Loop Which Circulated the Fuel
Mixture (No. 30) NaF-ZrF,-UF, (50-46-4 mole %)
for 1000 hr at a Hot-Leg Temperature of l5000F.
a,. 250X. Reduced 32.5%.
138
(No. 107) NaF-LiF-KF-UF, (1 1.2-41-45.3-2.5
mote %) circulating at a hot-leg temperature of
15OOoF. Loops 808 and 809, which were scheduled
to operate 1000 and 1500 hr, respectively, were
terminated before completion of the scheduled 5
operating period because of excessive oxidation
of the outside surface of the monel tubing. The
oxidation did not completely penetrate the tube
wall in either loop. Metallographic examination
revealed hot-leg attack to a depth of 1 mil, as
shown in Fig. 3.1.6, in all these loops. Three
other monel loops, 880, 881, and 882, that had
been chromium-plated to provide oxidation pro-
tection were operated under the same conditions,
but, apparently, the platings were imperfect,
and two of these three loops, 881 and 882, were
Fig. 3.1.6. Region of Maximum Attack of Hot
Leg of Monel Thermal-Convection Loop 809 Which
Circulated the Fuel Mixture (No. 107) NaF-LiF-
KF-UF, (11.2-41-453-2.5 mdle %) for 1027 hr at
a Hot-Leg Temperature of 15000F. Etched with
HN03-acetic acid. 250X. Reduced 32.5%.
TABLE 81.5. CHEMICAL ANALYSES OF THE FUEL MIXTURE (No. 30) NoF-ZrF4-UF4 (50-46-4 mole 46)
BEFORE AND AFTER CIRCULATION FOR 1000 hr AT 15OO0F IN HASTELLOY X AND W
THERMAL-CONVECTION LOOPS
Loop Loop Uranium Content Impurities Found (ppm)
Sample Token
No. Materia I (* 46) Ni Cr Fe
857 Hartalloy X Before filling 8.39 260 135 115
After draining 8.68 40 1060 125
873 Hastellay W Before filling 8.78 80 60 75
After draining 8.82 85 275 110
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