THE EFFECT OF THE TEMPERATURE AND OF THE MICROSTRUCTURE OF SINTERED BERYLLIUM OXIDE ON THE THERMAL NEUTRON SCATTERING CROSS SECTION

Journal Article · Sat Sep 01 04:00:00 EDT 1962 · At. Energ. (USSR)

OSTI ID:4803954

Zhezherun, I F; Sadikov, I P; Chernyshov, A A

One of the chief causes affecting the temperature coefficient of the reactivity of BeO-moderated reactors is the change of the effective scattering cross section together with the related temperature-related changes of the diffusion length of thermal neutrons. In view of the difficulties involved in the computation of these values, the changes of the scattering cross section of BeO as a function of temperature were determined experimentally; an attempt was also made to establish whether the sintered oxide presents any anisotropy that may have to be taken into account in reactor calculations. A mechanical neutron selector, installed in the horizontal beamhole of the RFT reactor, was used for the tests; the system which included the time analyzer allowed a resolution of 4 to 10% in the 0.003 to 0.1 ev range, was calibrated by the resonance absorption of Cd. The total effective cross section sigma /sub t/ of the specimens was determined at 290, 800, 1300, and 1500 deg K. The sigma /sub t/ value of BeO specimens having various microstructures was determined at room temperature. It was found that variations in the texture cause only a slight anisotropy of the scattering but the crystalline grain size influenced sigma /sub t/ more markedly. It is concluded that the grain size should not exceed 10 microns in order to maintain the scattering cross section at its heghest value. (TTT)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-16-033528
• OSTI ID: 4803954
• Journal Information: At. Energ. (USSR), Journal Name: At. Energ. (USSR) Vol. Vol: 13
• Country of Publication: Country unknown/Code not available
• Language: Russian

Related Subjects

ABSORPTION
ANISOTROPY
BERYLLIUM OXIDES
CADMIUM
CHOPPERS
CROSS SECTIONS
CRYSTALS
DIFFUSION LENGTH
ENERGY RANGE
GRAIN SIZE
LATTICES
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
MODERATORS
NEUTRON BEAMS
NEUTRON SPECTROMETERS
PULSE ANALYZERS
QUANTITATIVE ANALYSIS
REACTIVITY
RESOLUTION
RESONANCE
SCATTERING
SINTERED MATERIALS
STANDARDS
TEMPERATURE
TESTING
THERMAL NEUTRONS
TIME ANALYZERS