ORNL-1771 - Oak Ridge National Laboratory

Bulk Shielding Facility
The use of a graphite reflector as a shield com-
ponent ha5 been investigated at the Bulk Shielding
Facility (BSF) with measurements of attenuation
through various thicknesses of the material (Sec.
13). The fast-neutron spectrum of the BSF reactor
from 1.3 to 10 Mev through 1 ft of graphite was
also measured. Removal cross section values for
the carbon were determined to be 0.82 barn for a
I-ft slab, 0.84 barn for a 2-ft slab, and 0.80 barn
for a 3-ft slab.
An experiment has been performed at the BSF
to provide an experimental basis for future esti-
motes of the amount of visible light around a
nuclear-powered aircraft. Measurements in an air-
filled tube placed against the reactor have indi-
cated thot the maximum glow will occur at a
pressure corresponding to an altitude of about
30,000 ft.
In a proposed method for the determination of
the power of the ARE, the relative activity of the
PERIOD ENDING SEPTEMBER IO, 7954
fuel samples exposed in the ARE and in the known
flux of another reactor is measured. The method
has been tested at the BSF.
Tower Shielding Facility
Measurements of the ground and air scattering
of neutrons have been made at the Tower Shielding
Facility (TSF) (Sec. 14). A preliminary analysis
indicates that the contribution at the maximum
altitudes (around 200 ft) is between 2 and 5% of
the total scattered neutrons for differential ex-
per iments.
A new procedure for a calorimetric determination
of the power of the TSF reactor has been devised
which is based on the relationship between the
rate of temperature rise in the water of the reactor
tank and the reactor power. The resuits of three
experiments were consistent to within 1%. The
next series of tests at the TSF will be on the
GE-ANP R-1 divided-shield mockup.
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