ORNL-4191 - the Molten Salt Energy Technologies Web Site

L
a) CA
40''
5
2
5
5
2
to7
5
2
ORNL-DWG 67 12233
0 io 20 30 40 50
CllSTANCE FROM SURFACE (mils)
Fig. 9.3. Distribution Profile of lo6Ru in Graphite
from MSRE Core.
values previously ohtained after 7800 Mwhr. I1
is clear from this table that the data for 99Mo,
* 2Te, and Ku are generally similar, while
the values obtained for "Nb and 952r are ap-
preciably higher for the longer exposures. It
should be noted that the data for 95Nb are ob-
tained from gamma scans without chemical sep-
arations and are probably less certain than the
others.
The graphite samples accumulated by milling
these bars were analyzed for uranium by neutron
activation. Typical data from one of these bars
I
123
....... 1.-
ORNI.--0WG 67- 12234
..... __A
...._..___
0 io 20 30 40 SO
DISTANCE FROM S[JW/iC€ (mils)
407 I 1
~ .....
i
I 1 1 1
Fig. 9.4. Distribution Profile of 95Zr in Graphite
from MSRE Core.
are shown as Table 9.5. It is clear from this
table that the 23sU is present in all faces of
the graphite and that the concentration diminishes
with the depth of milling. The small concentration
in the blank (as in blanks from other specimens)
indicates strongly that these uranium concentrations
are real.
'me absolute quantity of 235U or of uranium in
the graphite moderator is apparently very small.
If these analyses are, in fact, typical of those
in the 2 x 2 in. moderator bars, then the average
concetitration of 235U in and through the bars