A t the tempmature of interest in molten-salt reactors, that is,
l@O0F, %he same trend of relative corrosiveness of the different salts may exist for Inconel, but the low rates of attack observed I n t e s t s pre-
clude a conclusive decision on this point. S i m i l a r l y , if there is any preferential effect of the base salts on INOR-8, the smaU anounts of attack tend t o hide it. expected from the theory, the corrosion depends sharply on the UFb concentration. Studies of the nuclear properties of molten-salt power reactors have indicsted (see part; 4) that the UF4 content of the fuel will usudlly be less than 1mole $, and therefore the corrosiveness of salts with higher UF4 concentrations, such as those described in Table 3.2, w i l l be avoided. As
The &reme effect of t q e r a t u r e i s also clearly indicated i n Table 3.2. In general, the corrosion rates a;re three t o six tines higher at 15OOoF than at l25OoF. "his effect is further enrphasized in the photomicrographs presented in Figs. 3.3 asld 3.4, which offer a campasison of mtaUogt.aphic specimens of Inconel that were exposed t o similar salts
of the I?&F-ZrF4-UF4 system at l50O0F and at 1250째F. A metallographic specimen of Inconel that was exposed at 1250째F t o the salt proposed for fueling of the molten-salt power reactor is shown in f i g . 3.5. !l?he effect of sodium on the structural materials of interest has
also been extensively studied, since sodium is proposed f o r use as the intermediate heat transfer medium. Corrosion problems inherent in the u t i l i m t i o n of sodium f o r b a t transfer purposes do not involve BO much the deterioration of meted. surfaces as the tendency f o r conlponents the container material t o be transported froan hot t o cold regions and sitedmaterial in the cold region. As in the case mixture, the mass transfer in sodium-
containing systems i s extremely dependent on the maximMl system operating The results rous t e s t s indicate that the nickel-base isf actory containers f o r sodium 8s Bconeland
.
,