ORNL-4191 - the Molten Salt Energy Technologies Web Site

This uranium species disappeared slowly when iron
wire was introduced into the melt. The resultant
spectrum was that of tetravalent uranium; thus, it
is demonstrated that an oxidized species of uranium
was oiiginally present. It would appear, then, that
although Si0 containers are stable to oxidation,
the equilibrium 0 '- concentration may react with
components of the melt.
The work on electrochemical generation of solute
species and their spectrophotometric characterization
is ~ontinuing.~ This work is carried out in
cooperation with F. L. Whiting' and Gleb
Mamantov. Again SiO, would offer several
advantages in this study compared with windowless
cell techniques which had been used. Under
the experimental conditions presently required,
however, it was found that the presence of 1 atm
of SiF, gas over the melt under study interferes
with cathodic voltammetric studies by causing
very high cathodic currents. The reasons for this
are not yet understood, but the IJ(IV)/U(III) reduction
wave is completely lost in the presence of
SiF,. Conversely, SiF, does not affect anodic
voltammograms. Since SiF, is a product of fluoride
salt reaction with SiO,, these results suggest that
SiO, containers may have limited use in voltam-
metric studies.
The development of a recording spectrophoto-
metric system is continuing that wilj permit spec-
tral measurements of highly radioactive solutions
to be obtained on samples located in a high-
radiation-level cell. The system will make use of
the extended optical path length similar to that
being considered for use in the in-line spectral
measurements of molten-salt reactors. The basic
spectrophotometer and associated equipment have
been ordered, and the design of the physical and
optical arrangements of the components for the
extended path is being considered. The optical
arrangement will be such that both windowed and
windowless cells can be used.
14.6 ANALYSIS OF OFF-GAS
FROM COMPATIBILITY TESTS OF MSRE
PUMP OIL WITH BF,
C. M. Boyd
A total hydrocarbon detector and a thermal
conductivity detector have been used to determine
the hydrocarbons and BF, in the gas from tests
on the effects of BF3 on MSRE pump oil (Gulf-
172
spin 35). These tests are described in an earlier
section. A gas sampling manifold permits the
measiirement of increases in hydrocarbon concen-
tration of an He-BF3 stream on contact with the
oil. A parallel stream of helium through a separate
oil reservoir serves 3s a reference. The hydro-
carbon analyzer was modified by the addition of a
sampling pump which draws in the gas at near
atmospheric pressure, compresses it, and then
passes it through the analyzer. The portions of
the test gas to be analyzed were first passed
through a saturated solution of KF to remove the
BF3 and thereby protect the pump and other
components of the analyzer. This solution has a
low water vapor pressure, which prevents water
condensation in the analyzer. In the first tests,
with the BF, at the 2000-ppm level and the oil at
15O0F, the hydrocarbon level in the off-gas was
less than 50 ppm~
The thermal conductivity detector was used to
monitor the BF3 concentration in the test gas,
which was produced by mixing flows of pure RF,
and He. The detector and flow capillary were
calibrated by passing a known volume of the gas
mixture through the detector and then through a
trap of dilute NaOH. The solution was analyzed
for boron and fluoride, and the BF3 concentration
of the gas was then calculated. The sensitivity
of this detector under the conditions used was
+I0 ppm of BF,.
14.7 DEVELOPMENT OF A GAS
CHROMATOGRAPH FOR THE MSRE
BLANKET GAS
C. M. Boyd A. S. Meyer
Developinent studies are being made on the
design of a gas chromatograph to be used for the
continuous determination of permanent gas im-
purities and water in the helium blanket gas of the
MSRE. The chromatograph will require two columns
to separate the components desired. Tests have
shown that a parallel column system composed of
a SA molecular sieves coluliln and a Porapak S
column should be practical for analyzing gases
which are not highly radioactive. The M,, O,,
7J. P. Young, MSK Program Serniann. Progr. Rept.
Feb. 28, 1967, ORNL-4119, p. 163.
'University of Tennessee, Knoxville.