ORNL-4191 - the Molten Salt Energy Technologies Web Site

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ORNL- DWG 67-(?.?35
0 10 20 30 40 50
DISTANCE FROM SURFACE (mils)
Fig. 9.5. Distribution Profile of 132Te in Graphite
from MSRE Core.
is much less than 1 ppm. Since the MSRE con-
tains about 70 ft3 or slightly less than 4000 kg
of graphite, the total 235U in the moderator stack
is almost certainly less than 4 g. Since the MSRE
fuel is slightly inore than 30% enriched in 235U,
the total uranium in the moderator should be, at
most, 10 to 15 g.
Examination of Hastelloy N
The graphite specimens described above were,
as was the case for the specimens examined after
7800 Mwlir, contained in a cylindrical, perforated
holder of I-Iastelloy N. Samples were cut from this
cylinder as
and analyzed by standard
techniques for several fission products and for
23513..
5
2
to”
(09
5
2
108
0 to 20 30 40 50
DISTANCE FROM SURFACE lrntls)
Fig. 9.6. Distribution Prafile of 140Ba in Grnphite
from MSRE Core.
Data are shown in Table 9.6 for seven fission
product isotopes and for uranium at five positions
from the top to the bottom of this Hastelloy N assembly.
Data are also shown for the comparable
samples examined after 7800 Mwlir of operation
in mid-1966.
It is clear from these data that the behavior of
”Mo was similar in the two sets of specimens,
with the 24,000-hr exposures generally showing
somewhat more deposited activity. Behavior of
the 132Te seems generally similar in the two exposures.
Somewhat more 103R~~ was found on the
24,000-Mwhr specimens than on those previoiusly
examined, while ’Zr (present in small amounts,
in any case) seems less concentrated on the
specimens exposed to the higher dosage. Iodine-
131, which is prcsent in appreciable concentrations,
shows some scatter with location of the