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PHOTO74665A
- Pi PE
F-05 PLI JG
Fig. 18.13. Plug Formed in Hastelloy N Loop 10 Containing NaF-KF-BF3 (48-3-49 mole %) After 8765 hr at
1125OF. AT= 265OF. 8 ~ . Reduced 23.50%.
estimate of the stoichiometry of the deposit is
2NaF-FeF ,-CrF ,-BF,. Metallographic examination
of the hot-leg specimens disclosed only moderate
surface roughening.
Loop 10, fabricated from Hastelloy N, operated
without incident for 8335 hr, at which time the
hot-leg temperature increased about 50"F, ac-
companied by a simultaneous temperature decrease
of the same magnitude in the cold leg. A pertur-
bation of this type is usually an indication of
plugging. The temperature fluctuations ceased
after 1 hr, and no further incidents occurred during
the life of this loop. The loop was shut down
after its 1-year scheduled operation. Examination
of the loop piping disclosed a partial plug in the
lower portion of the cold leg (Fig. 18.13). The
plug, which closed approximately 7
sectional area of the pipe, was emerald green in
color and analyzed to be essentially single crys-
tals of 3NaF-CrF,.6
Analysis of the drain salt cake from loop 10,
Fig. 18.14, revealed extensive increases in the
concentrations of Ni, Mo, Fe, and Cr when com-
pared with the before-test salt. Nickel was par-
ticularly high in the bottom and top portions of
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