ORNL-2106 - the Molten Salt Energy Technologies Web Site

ANP PROJECT PROGRESS REPORT
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5
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ORNL-LR-DW I4917
1
0 0.04 0.08 a12 0.16 0.20 0.24
THICKNESS OF LAYER (em)
Fig. 1.2.2. Heating in Copper-Boron Layer By
Alpha Particles from the B"(n,a)Li' Reaction.
The heating from sources 10 to 14 was neg-
lected. Their combined contributions to the
heating in the region being considered was
estimated to be about 5% of the total heating.
The fuel region of the core of the reactor was
assumed to be a spherical shell 5.125 in. thick
with an outside radius of 10.5 in.' This region
was divided into13 spherical shells of thicknesses
varying from 0.27 cm to 2 cm. The source strength
(in watts/cm3) of the prompt gamma rays in each
shell was assumed to be proportional to the
average fission power in each shell, which was
calculated (from ref. 2) at the equatorial plane of
'w. L. Scott, Jr., Dimensional Data for ART, ORNL
CF-56-1-186 (March 13, 1956).
2A. M. Perry, Fission Power Distribution in the ART,
ORNL CF-561-172 (Jan. 25, 1956).
30
the reactor. The source strength of the decay LJ
gamma rays was assumed to be the same for each
fuel shell.3
The average source strength of gamma rays
resulting from inelastic neutron scattering in the
fuel was calculated4 by using the output of
multigroup calculations5 performed by the Curtiss-
Wright Corp. on ART-type reactors with spherical
t
symmetry.6 The inelastic cross sections used
for the fuel were those reported in ref. 3. This
calculation had been performed before all the
data in the latter reference had been accumulated,
so it was assumed that, for each inelastic
collision, one-half the average neutron energy in
each energy group was given off as I-MeV gamma
radiation. Calculations made by using the more
recent data indicate that the source strength
used was too high by about 50%. The total heating
values given in Fig. 1.2.1 may therefore be about
5% too high. This error is partially compensated
for, however, by the neglect of sources 10 through
14.
The prompt and decay gamma-ray spectra7
were divided into four energy groups with average
energies for each group of 0.5, 1, 2, and 4 Mev.
The last four groups listed in ref. 3 were combined
into one group with an average energy of 4 Mev.
The heating at the various places described in
Fig. 1.2.1 was calculated by summing the contributions
from each energy group from every fuel
shell.
It was assumed for the calculations that each
fuel shell was replaced by an infinitely thin
spherical-she1 I source embedded in an infinite
homogeneous medium so that the standard transformation
from a spherical-shell source to two
L
infinite-plane sources would apply, that is, so
that the heating at R, h(R), would be given by
(1) h(R) = _L. [ H(R - Y) - H(R + Y) ,
R 1
3H. W. Bertini et al., Basic Gamma-Ray Data for
ART Heat Deposition Calculations, ORNL-2113
(in press).
4Calculatio~ir performed by R. B. Stevenson, Pratt 8,
Whitney Aircraft, private communication to H. W.
Bertini.
'S. Strauch, Curtirs-Wright Corp., private communi-
cation to H. W. Bertini.
6H. Reere, Jr., S. Strauch, and J. Michalcozo,
Geometry Study far an ANP Circulating Fuel Reactor,
WAD1901 (Sept. 1, 1954).
7H. W. Bertini, C. M. Copenhaver, and R. B. 2
Stevenson, ANP Quar. Prog. Rep. March 10. 1956.
ORNL-2061, P 35.
c
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