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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963

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This paper was submitted for publication
in the open literature at least 6 months
prior to the issuance date of this Micro-
card. Since the U.S.A.E.C. has no evi-
dence that it has been published, the pa-
per is being distributed in Microcard
form as a preprint.
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LEGAL NOTICE
This report was prepared as an account of
Government sponsored work. Neither the
United States, nor the Commission, nor any
person acting on behalf of the Commission:
A. Makes any warranty or representa-
tion, expressed or implied, with respect to
the accuracy, completeness, or usefulness
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or that the use of any information, appa-
ratus, method, or process disclosed in this
report may not infringe privately owned
rights; or
B. Assumes any liabilities with respect
to the use of, or for damages resulting from
the use of any information, apparatus,
method, or process disclosed in this report.
As used in the above, “person acting on
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employee of such contractor, to the extent
that such employee or contractor of the
Commission, or employee of such contractor
prepares, disseminates, or provides access
to, any information pursuant to his employ-
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his employment with such contractor.

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ORNU P-874
CONF.6505ole
ITIES
EXPERIENCE WITH UNUSUAL TECHNIQUES USED IN
ORNL DEPLETION CODES*
.
fatura mate of the no even
in the of the issua, S.A.E.C. ishod, the de
.
BIL
This paper was rublaitted for publication
in the opon literaturo at loan shaonths
prior to the issuanco date of this Micro-
card. Since the 1.8.A.E.C. has no evi-
donce that it has boon published, the pa-
per is being distributod in Microcard
form as a preprint.
D. R. Vondy
Oak Ridge National Laboratory
Oak Ridge, Tennessee
card. but it bas boord in MIC
دن تا این پایانی
Several of the reactor depletion codes developed at ORNL contain
some novel features which have proved useful either in accelerating the
III.
computations involved, or for improving their accuracy. The codes TONG,
based on a space-independent flux model, and EQUIPOISE BURNOUT and
ASSAULT, based on two-dimensional diffusion theory, yield explicit
solutions to the general nuclide chain equations over time intervals,
,
within which the neutron energy spectrum remains fixed; at the beginning
t's
X
of each new time interval, the neutron distribution is recomputed. In
all the codes, an arbitrary, scattering matrix for linking the neutron
energy croups is permitted. Other characteristics of the programs are
enumerated in Table 1.
The principal point of interest 18 the way in which criticality is
maintained throughout core life. In these codes, the variable to be
adjusted to maintain criticality, for example the concentration of a
--
-
control poison, is made the eigenvalue of the criticality problem. This
procedure, essentially an extension of the Equipoise method, circumvents
the need to obtain converged solutions for the flux and multiplication
factor with trial values of the poison concentration, instead, the dem.
sired solution, for k = 1, or any other specified value, 18-obturing
as the direct result of a single convergence problem.
value, 18
p otranno es
HODISTRIBUCUNTURITANNIEN 17:
** **CONTATTIS. NOTTING DE PATENTERA
* Www.hhSEDURES-BA fits REMETVING
van
SECTION,
* Recearch sponsored by the U. S. Atomic Energy Commission under
contract with the Union Carbide Corporation. ..
APPROVED FOR PUBLIC RELEASE
XCA
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.*
S.
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Table 1. Description of DepJetion Codes
Number
Geometric
Dimensions
Neutron
Groups
Code
Direct
Search
Nuclide
Cross
Section
Sets
of
Normal Use
Example
TBM-7090
Time
(Hrs)
Nuclides
0
30
75
1,000
i
TONG
(multi-zone)
EQUIPOISE
BURNOUT
ASSAULT
Many cycle, long history
for large cores
Well behaved cores
1
2
2
100
200
8,000
poison
Fuel,
poison
Fuel,
poison
Poison,
source
~ 20
200
-
12,000
Cores with complex
neutron spectra
7
2-
A second valuable feature of these codes is a more general treat-
meni of the nuclide chain equations than has customarily been emp].oyed
in reactor depletion codes. Provision 18 made for several independent
or related chains of nuclides, the identity of the chains being speci-
fied as part of the input. Branched chains are allowed in TONG and
ASSAULT, and this permits, for example, a more rigorous treatment of
the fission product sequence including promethium and samarium.
Comments will be made regarding the accuracy to be expected in
· problems involving long chains, and on the effect or the number of
groups, number of space points, and convergence criteria on speed and
accuracy for various types of reactors.
KL
9/10/65
DATE FILMED
END
ULCAIYO NYUMAT
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