ORNL-1771 - Oak Ridge National Laboratory

uranium hexafluoride with a molten NaF-ZrF, salt
bath (at 65OOC) in which the UF, is insoluble in
the presence of excess fluorine. The uraniurn loss
in the scrubbing step was less than 0.001%. Frac-
tional distillation of the UF, from this step, which
would be performed in order to obtain complete
decontamination, could be carried out in only lightly
shielded equipment.
Two experiments on scrubbing UF, with molten
NaF-ZrF, were carried out. In one, un acetone-dry
ice cold trap was used between the fluorination and
scrub steps; the uranium hexafluoride was con-
densed (and thus separated from excess fluorine)
in the cold trap and was then resublimed from it.
The uranium was recovered from the scrub salt by
Gross
Ru
Zr
ldb
TRE
cs
Sr
Ba
PERIOD ENDING SEPTEMBER 70, 1954
refluorination. In the second experiment no cold
trap wos used, but the decontamination obtained
was the same (Table 1.1). It is thought that
resublimation of the salt-scrubbed product would
achieve additional decontamination.
Synethetic ARE fuel was prepared for the two
runs by dissosving a 224-day-irrodiated, 30-day-
cooled, 6-9 miniature uranium slug in NaF-ZrF,
(56-44 mole %) at 650°C by passing HF through
the molten bath. The final NaF-ZrF,-UF, mixture
had a composition of 54.0-42.4-3.6 mole % and
activity of 5 x lo6 beta counts per minute per
milligram of uranium. The dissolution and subse-
quent fluorination were carried aut in the same
nickel reactor. in each run the scrub salt was
TABLE 1-11. DECONTAMlNATlON OBTAINED BY MOLTEN SALT SCRUBBING OF UF6
IN THE FLUORIDE VOLATlLlT'Y PROCESS
6
Synthetic ARE fuel; beta activity of 5 x 10 counts per minute per milli-
Act; vi ty
gram of uranium; fluorinated at 650°C with elemental fluorine gas at flow
rate of 66 rnl/rnin
Run A:
Run B:
In fluorination salt
In resublimation trap
In scrub salt
Fluorination period of 3 hr; UF plus excess fluorine passed
6
directly
to scrub salt from the fluorination step
Fluorination period of 5hr; UFg condensed in cold trap andrcsub-
limed from it prior to scrubbing and recovered from scrub by re-
fluorination
Run A
Beta Decontamination Factors
.......................................... ___
Run B
. ............................ ~
Scrub Over-al I Scrub Oves-all
2 x 10,"
2 x IO4*
6 750 1.4 430
3 >7 x IO4
9 1 x IO5
4 700 8
4
a Y 10
90 >8 x 104 3 2 x IO4
4
130 '~3 x 16
20 23 ,? 106
>8 ? IO5
Uranium Losses (X of Initial Charge)
l*4
0.23
131
*Calculated onthe gross Ru, Zr, bib, and 'TRE activity rather khan on *otd activity, which included much due to I .
This does not materially affect comparison with pruwioi~s gross beta decontcmination datu,
3 x
0.74
40-3
13