ORNL-1771 - Oak Ridge National Laboratory

The thermal-neutron flux (Fig. 13.2) was measured
behind each of the three graphite slab thicknesses
to a distance of 300 crn from the reactor face,
Measurements were made with a 3-in. U235 fission
chamber, an %in. BF, counter, and a 124-in. 1 BF,
counter,
foil data.
and the data were normalized to indium
Fast-neutron measurement5 (Fig. 13.3) were
made with a three-section neutron dosimeter.
Gamma-ray measurements (Fig. 13.4) were taken
PERIOD ENDING SEPTEMBER 70, 7954
behind each of the three graphite slab thicknesses,
both to determine the magnitude and relaxation
lengths of the gamma-ray dose through graphite and
to ensure that none of the neutron detectors was
being used in a too high gamma-ray field, which
would have caused their readings to be high.
The fast-neutron spectrum from 1.3 to 10 Mev was
measured with the BSF fast-neutron spe~trometer.~
A spectrum with reasonable statistics could be
obtained only through the 1-ft graphite slab; the
neutron intensities through the 2- and 3-ft sections
were too low, The spectrum measured with the
-.
3R. G. Cochran and K. Henry, A Protun Kecozl Type
Fast-Neutron Spectrometer, ORNL- 1479 (April 2, 1953).
5
..... !. I .....
1 ,
Fig. 13.2. Thermal-Neutron Flux Measurements ose Measurements Be-
Behind AGHT Graphite.
169