THEORY AND USE OF SMALL SUBCRITICAL ASSEMBLIES FOR THE MEASUREMENT OF REACTOR PARAMETERS

Technical Report · Sun Apr 01 04:00:00 EST 1962

OSTI ID:4811314

Peak, J C; Kaplan, I; Thompson, T J

The use of small subcritical assemblies for the measurement of reactor parameters in the preliminary study of new types of reactors was theoretically and experimentally investigated. Age-diffusion theory was applied to a cylindrical subcritical assembly with a thermal neutron source on one end. The solutions allow calculation of the thermal flux due to the source, the thermal flux due to neutrons born and moderated in the assembly, and the slowing down density at any particular age, for any point in the assembly. Methods of correction for source and leakage effects in small assemblies were developed for measurements of lattice parameters. Three dimensionless parameters were shown to characterize the size of an assembly in terms of its neutron behavior. Three other measures were advanced by which a proposed experimertal position in a subcritical assembly could be evaluated. Tables illustrating the use of these parameters and measures are presented for 128 possible subcritical assemblies. The small assemblies were moderated with mixtures of light and heavy water. The following experimental measurements were made in each assembly: axial and radial flux traverses with bare and cadmium covered gold foils, uranium-238 cadmium ratio in a rod, uranium-238 to uranium-235 fission ratio in a rod, and intracell flux traverses with bare and cadmium covered gold foils. The results are promising enough that further theoretical and experimental research on small subcritical assemblies is justified. (auth)

• Research Organization: Massachusetts Inst. of Tech., Cambridge
• NSA Number: NSA-16-028367
• OSTI ID: 4811314
• Report Number(s): NYO-10204; MITNE-16
• Country of Publication: United States
• Language: English

Related Subjects

CADMIUM
CADMIUM RATIO
CONFIGURATION
CRITICAL ASSEMBLIES
CYLINDERS
DIFFERENTIAL EQUATIONS
DIFFUSION
ERRORS
FERMI AGE
FISSION
FOILS
FUEL ELEMENTS
GOLD
HEAVY WATER MODERATOR
LAYERS
LEAKS
LOSSES
MEASURED VALUES
NEUTRON FLUX
NEUTRON SOURCES
NEUTRONS
REACTIVITY
REACTOR CORE
REACTOR TECHNOLOGY
RODS
SLOWDOWN
SPECTRA
TABLES
THERMAL NEUTRONS
URANIUM 235
URANIUM 238
USES
WATER MODERATOR