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15. TOWER SHIELDING FACILITY
C. E. Clifford
T. V. Blosser
J. L. Hull
L, B. Holland
F. N. Watson
Physics Division
D. L. Gilliland, General Electric Company
M. F. Valerino, NACA, Cleveland
J. Van Hoomi ssen, Boeing Airplane Company
-ANP R-1 divided shield mockup
ements of the radiation around
the reactor shield in the Tower Shielding Facility
(TSF) reactor handling pool. The experimentation
thus far has also included thermal-neutron flux and
some aamma-ray dose rate measurements in the
ated a horizontal distance of
shield. This work was in-
of two and one-half weeks so
e TSF could participate in an Air Force
in which a group of monkeys were exposed
massive neutron radiation doses. The work on
the G-E experiment has now been resumed.
Analyses of some aspects of the TSF data have
been completed and are presented in Sec. 12,
“Sh i el di n g An al y s i s. ”
TSF EXPERIMENT WITH THE MOCKUP OF
THE GE-ANP R-1 SHIELD DESIGN
T. V. Blosser
D. L, Gilliland
J. Van Hoomissen
F. N. Watson
The mockup of the GE-ANP R-1 reactor shield
design (Fig. 15.1) is being used at the TSF for a
series of measurements. Fast-neutron and gamma-
ray dose rates were measured around the reactor
shield section while it was submerged in water in
the reactor handling pool. In addition, thermalneutron
flux and gamma-ray dose rate measurements
have been made in the detector tank located a
fixed horizontal distance from the reactor shield.
The reactor loading for this experiment (Fig.
15.2) was a 5 x 7 fuel element array which gave a
etrical power distribution throughout the retor.
In order to avoid excess reactivity, a fuel
t was removed from the center of each of
-element faces. The measurements
t the points indicated in Fiq. 15.1
ulk Shielding Facility Tests on
ShieldMockup, ORNL CF-54-8-94
ANP Quar. Prog. Rep. Mar. 10,
-
were compared with similar measurements made
earlier at the BSF.’
In general, the BSF and TSF data were in agree-
ment, as is indicated in Figs. 15.3 and 15.4. How-
ever, they were not in complete agreement, largely
because of differences in the experimental setups
at the two facilities. For example, while the TSF
had a symmetrical power density distribution, the
fuel element loading at the BSF gave an asym-
metrical distribution which had a maximum 8.1 cm
from the center line of the reactor grid. Also,
only compartments A and D contained borated water
at the BSF, whereas at the TSF all compartments
contained borated water for the first in-pool meas-
urements. Later, plain water was used in Com-
portment D. The BSF boration was 1.1 wt %, while
the TSF boration was 0.85 wt %. For the measure-
ments off the rear section at the BSF, no lead or
iron side shielding was present, while at the TSF
the side shielding shown in Fig. 15.1 was in
position, For the measurements off the front and
side sections, the side shield at the BSF had a
total of 1 in. less steel than the side shield at the
TSF.
Measurements of the neutrons scattered into the
side of the detector tank (located a horizontal
distance of 70.8 ft from the G-E reactor shield)
were made as a function of altitude. The flux
(Fig. 15.5) is a slowly varying function of the
altitude, and it exhibits a peak at about 35 ft.
A decrease of about 6% in the readings between
150 and 200 ft indicates that the ground-scattered
neutrons are still observable at these altitudes for
this particular reactor-shield combination. The
shape of the curve is quite different from that ob-
tained in the differential shielding experiments
with the water tank,:! because the G-E shield
2C. E. Clifford et aL, Preliminary Study of Fast Neutron
Ground and Air Scattering at the Tower Shielding Facility,
ORNL CF-54-8-95 (Aug. 23, 19541.