ORNL-1816 - the Molten Salt Energy Technologies Web Site

flux (Fig. 15.6) along the y axis (coincident with
" the reactor-detector axi s) exhi bits an average relaxation
length of 5.0 cm in the water between the
rear face and the lead. This indicates that these
- 5 neutrons are largely air-scattered neutrons, as
would be expected, since the thick neutron shadow
shield eliminates the direct beam. The apparent
- transparency of the lead is suspect, since the
possibility exists that neutrons were streaming in
through the lead from the side of the detector tank.
An x traverse (Fig. 15.7) was taken in order to
indicate the attenuation to be expected from the
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Reactor in GE-ANP R-1 Mockup.
PERIOD ENDING DECEMBER 10,1954
crew compartment side shielding, The apparent
relaxation length, which is not constant, is very
short, 4.2 cm, in the first few centimeters of pene-
tration and increases to 6.0 cm between 25 and
40 cm of penetration. This short relaxation length
is probably indicative of the large number of low-
energy neutrons escaping through the air ducts in
the reactor shield.
In a y traverse (Fig. 15.8) the gamma relaxation
length is approximately 13 cm at the front of the
detector tank and approximately 17 cm at the rear
of the tank.
x -67.5 cm
SEeREf
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