ORNL-4191 - the Molten Salt Energy Technologies Web Site

I I
' 32 5 in
0007 inches
iTi
230
LOOP 10
SALT NoF KF BF3 (48 3 49 mole%)
TEMPERATURE 1125DF,AT=2650F; TIME = 8760 hr
are, of course, the deleterious results of primary
concern.
I
Fig. 18.15. Surface Layers in Loop 10 after 8760 hr Operation.
Equipment Modifications
During the last six months extensive modifi-
cations were made to the thermal convection loop
area in Building 9201-3 so as to make it more
suitable for advanced studies on the compatibility
of MSBR salts with Hastelloy N and modified
Hastelloy N (0.5% Ti). All instrumentation has
been or is in the process of being upgraded, out-
moded furnaces are being replaced, and special
facilities have been installed to handle toxic BF,
gas. Two loops ready to be charged with BF,-
bearing salts are shown in Fig. 18.16. Our future
program includes operation of natural-circulation
and possibly forcedcirculation loops with the
prime candidate fuel, blanket, and coolant salts
for the MSBR (loops 13-16). A study will be made
of the compatibility of graphite-Hastelloy N braze
joints in fuel salt. Capsule tests to determine the
effect of BF, pressure on the compatibility of the
fluoroborate salts with Hastelloy N will also be
conducted.
ORNL-DWG67-9342
18.7. TITANIUM DIFFUSION
IN HASTELLOY N
C. E. Sessions T. S. Lundy
Titanium additions to Hastelloy N improve the
resistance of this alloy to damage by neutron ir-
radiation. However, we have some concern about
how the addition of titanium will influence the
corrosion resistance. Evans et al. have shown
that the primary corrosion mechanism of standard
Hastelloy N in pure fluoride salts is the leaching
of chromium by the reaction
UF, + Cr -+ UF, + CrF,
They demonstrated that the process was con-
trolled by the diffusion of chromium in the alloy.
Titanium will tend to undergo a similar reaction,
since the standard free energy of formation of
TiF is even more negative than that for CrF ,
'R. B. Evans 111, J. H. DeVan, and G. M. Watson,
Self-Diffusion of Chromium in Nickel-Base Alloys,
ORNL-2982 (Jan. 20, 1961).