CONSISTENT P1 ANALYSIS OF AQUEOUS URANIUM-235 CRITICAL ASSEMBLIES

Technical Report · Wed Nov 01 04:00:00 EST 1961

OSTI ID:4831545

Fieno, D

The lethargy-dependent equations of the consistent P1 approximation to the Boltzmann transport equation for slowing down neutrons were used as the basis of an IBM 704 computer program. Some of the effects included are linearly anisotroppc center of mass elastic scattering, heavy element inelastic scattering based on the evaporation model of the nucleus, and optional variation of the buckling with lethargy. The microscopic cross-section data developed for thts program covered 473 1ethargy points from lethargy u =0 (10 Mev) to u = 19.8 (0.025 ev), The value of the fission neutron age in water was calculated to be 26.5 square centimeters; this value was compared with the recent experimental value given as 27.86 square centimeters. The Fourier transform of the slowingdown kernel for water to indium resonance energy calculated compared well with the Fourier transform of the kernel for water as measured by Hill, Roberts, and Fitch. This method of calculation was applied to uranyl fluoridewater solution critical assemblies. Theoretical results established for both unreflected and fully reflected critical assemblies were compared with available experimental data. The theoretical buckling curve derived as a function of the hydrogen to U/sup 235/ atom concentration for an energy independent extrapolation distance was successful in predicting the critical heights of various unreflected cylindrical assemblies. The critical dimensions of fully water-reflected cylindrical assemblies were reasonably well predicted using the theoretical buckling curve and reflector savings for equivalent spherical assemblies. (auth)

• Research Organization: National Aeronautics and Space Administration. Lewis Research Center, Cleveland
• NSA Number: NSA-16-003611
• OSTI ID: 4831545
• Report Number(s): NASA-TN-D-1102
• Country of Publication: United States
• Language: English

Related Subjects

BOLTZMANN EQUATION
BUCKLING
COMPUTERS
CONFIGURATION
CRITICAL ASSEMBLIES
CROSS SECTIONS
CYLINDERS
DIFFERENTIAL EQUATIONS
DIGITAL SYSTEMS
EQUATIONS
FISSION
FOURIER ANALYSIS
HYDROGEN
IBM 704
LIFETIME
MATHEMATICS
NEUTRONS
OSCILLATIONS
PHYSICS
PROGRAMMING
REFLECTORS
SCATTERING
SLOWDOWN
TRANSPORT THEORY
URANIUM 235
URANIUM FLUORIDES
WATER