ORNL-1816 - the Molten Salt Energy Technologies Web Site

Study of the NaF-ZrF,-UF, system by the use
of various techniques, including quenching, thermal
analysis, and filtration, has continued. Improve-
ments that have been made in quenching methods
are expected to accelerate the availability of data
by this method, Phase studies of the UF3-bearing
fluoride systems have continued to be emphasized
because of interest in their favorable corrosion
characteristics, It is believed that problems
attendant to handling the easily oxidized UF,
will be alleviated to some extent by extending
phase studies to include LaF,, an isomorphous
stable substitute for UF,.
Investigations of the chemical reactions in molten
salts are continuing in an effort to understand the
mechanisms involved in the purification of fluoride
mixtures and in uction of UF, to UF, in
fluoride melts. studies of the corrosion
products of lnconel in fluoride mixtur
reduction of UF, by structural metals are under
way.
A sufficient stock pile of purified zirconium
ride mixtures wil
d of this calendar
termination of operation of the large-scale (250-lb
capacity) production facility. Careful control of
operating conditi in the pilot-scale facility has
allowed production of sufficiently consistent UF,
content material to oermit its release for corrosion
5. CHEMISTRY OF MOLTEN MATERIALS
W. R. Grimes
Materials Chemistry Division
PHASE EQUILIBRIUM STUDIES
C. J. Barton
Materials Chemistry Divi s ion
H. Insley, Consultant
Solid Phase Studies in the NaF-ZrF,-UF, System
C. J. Barton
R. E. Moore
L. M. Bratcher R. E. Thoma
Materia I s Chemistry Division
H. Insley, Consultant
Additional quenching data obtained with a number
of compositions in the NaF-ZrF,-UF, system have
1
es sent ia I I y confirmed previous I y reported f i ridi ng s.
There was some indication from thermal analysis
of mixtures along the Na7U6F3,-Na7Zr6F31 join
(formerly referred to as the Na,U8F,, -Nag,Zr8 F ,
join - the 7 to 6 ratio was adopted on the basis
of structural considerations2) that these com-
ponents may not form a complete series of solid
solutions. Preliminary petrographic and x-ray
diffraction studies of the slowly cooled melts lend
support to this view, but quenching data will be
obtained in order to assure that the crystalline
phases observed represent equi librium conditions.
The perspective diagram shown in Fig. 5.1, pre-
pared by R. M. Freestone, gives a picture of the
liquidus relationships in this system.
Quenching studies in this system are expected
to proceed at an accelerated pace because of the
use of a new quenching apparatus similar to one
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