ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORT
Preliminary work for further circulating-fuel
reflector-moderaked reactor shield experiments at
the Lid Tank Shielding Facility (LTSF) has con-
tinued with irrudiution in the ORNL Graphite
Reactor of a sample of the UF,-C,F,, mixture
that may be used to simulate the reactor fuel in
the shield mockup. Also, a new effective removal
cross section for carbon has been obtained for the
case iii which the carbon is distributed uniformly
throughout the shield.
Thermal- and fast-neutron measurements have
been mode around an array of three of the GE-ANP
helical air ducts, and a 35-duct array is being
assembled far further measurements. Difficulties
in fobricoting the enriched uranium plate for the
new LPSF SOUPCE have delayed the completion of
this project; however, it appears at present that
these difficulties hove beer1 surmounted. It is
anticipated that the installation will be completed
within a month.
RE FL ECYO W-MOB ERATE D W E ACTO W
AND SWIEI-D MQCKUP TESTS
J. 6. Dee
D. K. Trubey \N. Steyel't
A second series sf mockup tests for the circu-
lating-fuel reflector-moderated reactor (RMR) and
shield is being initiated at the LTSF.' For this
series Q larger tank (approximately a 6-ft cube) has
been constructed to hold all the dry components of
the configurations, as well as ow expansible plastic
bag for containing borated water. The beryllium
blocks to be used in the mockups will also be
placed in plastic containers for additional protection.
The dry tank face adjacent to the source plate
has a k-in.-thick Inconel window, which corre-
sponds to the RMR core shell. In order to determine
the effect of the lnconel on the gamma-ray dose,
1-
For first series see C. L. Storrs et al., ANP Quur,
Prog. Rep. Sept. 10, 1953, ORNL-1609, p 128.
1 64
G. T. Chapman
d, M. Miller W. Steyert
D. K. Trubey
Physics Division
.J. 5. Des
Pratt. and Whitney Aircraft Division
gamma mmsurements were taken in pure water in
the tank. The dose WQS higher by Q factor of 2
than thrrt normally observed in the LTSF, and the
increase agrees closely with the calculated 9-Mev
capture gamma-ray dose from the Inconel.
In addition to die presently planned static fission
source tests for RMR designs, a dynamic fission
source test is being considered for measuring the
sodium activation from delayed neutrons released
in the heat exchanger and the attenuation of gamma
rays from short-lived fission products. A liquid
being considered is C,F,, contairiing 20 wt % Uc-',.
In cooperation with the Radiation Damage group of
the Solid State Division, Q sample containing natural
uranium was irradiated in a fluorinated nickel
capsule in the OHNL Graphite Reactor for an inte-
grated flux of 1617 nvt, which compares with an
integrated flux of IOi5 nvt for the enriched fuel.
After the volatile pioducts hod been removed by
vacuum distillation, a precipitate containing most
of the radioactivity and a large part of the uranium
was found in the irradiated c~psules; thus, this fuel
mixture could not be used for long exposures. A
similar capsule test is being prepared for a shorter
exposurer and alteriiate solutions are being explored.
EFF ECTllVE REMOVAL
CROSS SECTION OF CARBON
0. K. TriJbcy
Measurements of the removal cross section of
carbon have been made in a continuous carbon
medium obtained by dissolving sugar (C,,H,,O,
in water, The solution (density = 1.312 k 0.001
g/cm3) contained 44.2 wt % sugar, which gave
0.354 g/cm3 of carbon and a hydrogen and oxygen
density that WQS 95% of that of plain water. It was
contained in ei large tank that had n &-in.-thick
lnconel window on the source side.
The therma I-neutron flux, the fast-neutron dose,
and the gamma-ray dose are shown as functions of
distance from the source in Figs. 12.1, 12-2, and