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ANP PROJECT PROGRESS REPORT
mixture showed quite anomalous behavior in that
the attack decreased markedly with the decrease
in ZrF,. These results are being rechecked.
The loops containing mixtures with 56 mole %
of the alkali-metal fluoride, with the exception of
the loop operated with the KF-containing mixture,
showed traces of metallic crystals in the cold
legs. These crystals were most pronounced in the
RbF-containing mixtures. Specimens of the
crystals found in loop 933, which circulated the
fuel mixture RbF-ZrF,-UF, (56-40-4 mole %), are
shown in Fig. 3.1.7.
Two additional Inconel loops, 883 and 884,
were operdted under similar conditions to obtain
further corrosion data for the KF-ZrF,-UF,
(50-464 mole %) system. An increase in the
operating time from 500 to 1500 hr caused an
increase in maximum attack of 2 mils. Thin
metallic layers were noted in the cold legs after
both operating periods. As yet these layers are
unidentified.
140
Fig. 3.1.7. Metallic Crystals and Layer De-
posited in Cold Leg of Inconel Thermal-Convection
Loop 933 Which Circulated the Fuel Mixture
(No. WRS) RbF-ZrF,-UF, (56-40-4 mole %) for
500 hr at a Hot-Leg Temperature af 15OOOF.
Etched with modified aqua regia. 250X. Reduced
32.5%.