the Molten Salt Energy Technologies Web Site

Figure 6. 8 is R photograph of t le
bent cylindrical ducts in position in
the Lid Tank Facility. There are 19,
round, aluminum pipes in a hexagonal
array. Each pipe has an outside
diameter of 3 15/16 in. and 1/16-in.
walls. The pipes have three straight
sections 22 in. long connected with
45-deg bends. In the plane of the
source plate, the centers of the
pipes define equilateral triangles
wit,h sides 7.33 in. long. Since the
ducts lecve the source plate at an
angle of 22.5 deg to the normal, the
array is not symmetrical about the
source axis. With this arrangement,
the fractions of the total volume thnt
are air, water, and aluminum are 26.6,
71.8, and 1.6%, respectively,
The radiation measurements around
this array have been obtained in considerable
detail. An analysis of the
results shows that the gamma dose can
TABLE 6.2. SUMMARY OF ACTIVITIES
SAMPLE NEUTRON SHIELD
Cobalt
M angane se
None
Boron cover
None
Boron cover
None
Boron cover
Boron backing
Boron cover
Boron backing
POSITION WATER AROLND DUCT
Outlet Duct
Eoron cover
- __
Side
Borated
-
-1 1 an g ane se None
No:-
Inlet Duct
End
Side
P1 ain
Plain
-_ __-- . - - - -
End
End
Side
Side
End
End
End
End
Side
PERIOD ENDING DECEMBER 10, 1952
be accurately computed by considering
the ducts and water to ].)e ahomogeneous
shield of appropriately reduced density.
The neutrons, however, stream through
the ducts in sufficient numbers to
increase the flux at the end to one or
two orders of magni tude greater than
that predicted on a reduced density
basis. This is in accordance with the
duct theory proposed by Simon and
Clifford, that is, geometrical attenu-
ation along the straight sections and
inverse sine reflection at the bends.
The design of this particular array is
not optimum, since the att,enuation
through the ducts is not high enough
to exceed that through the equivalent
amount of water. An optimum design
might. have another bend in the ducts
to increase their attenuation, or
closer spacing between ducts to further
reduce the density of the equivalent
homogeneous shield.
INDUCED IN THE LID TANK FACILITY
Borated
Borated
Borated
Borated
Plain
Plain
Borated
Borated
Borated
I___-
-I_
ACTIVITY INDUCED
( mc/ g)
58.1 i 9.6 X 10"'
5.5 f 9.1 X lo-''
138.3 f 10.1 X
18.3 f 9.3 X IO"'
178.5 f 1.5 X
4.64 f 0.17 X lom8
68.3 f 1.0 X
3.16 f 0. 16 X
124.3 f 0.8 X
11.7 i 0.3 X lo'*
1.04 t 0.15 x 10'
2.57 f 0.02 x 10'~
77