The Coupled Aspects of a Fast-Thermal Critical: ZPR-V

Technical Report · Tue Oct 01 04:00:00 EDT 1957

DOI:https://doi.org/10.2172/4347298· OSTI ID:4347298

Toppel, B. J. ^[1]

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1. Argonne National Lab. (ANL), Lemont, IL (United States)

ZPR-V is a zero-power, coupled fast-thermal critical assembly involving a dilute fast core and a H₂O-moderated, enriched uranium thermal annulus. The two regions are coupled through a natural U isolation blanket. This facility is useful in studying some of the properties of dilute fast reactor systems as well as those of coupled fast-thermal power breeders. Recent emphasis has been on the latter aspect of the problem and an investigation of the coupled aspects of the system has been made. An important parameter in the coupling concept is the division of reactivity. This can be determined by means of fast fuel substitutions and 1/v poisoning of the thermal annulus in conjunction with theoretical calculations. Auxiliary information obtained in such a procedure is the fast fuel worth throughout the core and the prompt neutron lifetime of the whole system. A second important parameter, S₁/S₂, is the relative number of neutrons emitted per unit time due to fast and slow fissions. Information regarding this quantity can be obtained with the aid of U²³⁵ and U²³⁸ fission distributions. Measurements of the above parameters were made for the case of a U²³⁸:U²³⁵ atomic ratio of 5:1 in the fast core and a 1-in. isolation blanket. The fractions of reactivity in the fast core, blanket, and annulus are, respectively, 24, 14, and 61%; the prompt lifetime is 39.0 ± 3.0 microseconds sec; the ratio S₁/S₂ is 0.43.

• Research Organization: Argonne National Laboratory (ANL), Lemont, IL (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• DOE Contract Number: W-31109-ENG-38
• NSA Number: NSA-12-003206
• OSTI ID: 4347298
• Report Number(s): ANL-5775
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BLANKETS
CRITICAL ASSEMBLIES
DISTRIBUTION
FAST NEUTRONS
FISSION
Fast Core
LIFETIME
MEASURED VALUES
NATURAL URANIUM
Nuclear Criticality Safety Program (NCSP)
POISONING
PROMPT NEUTRONS
Prompt Neutron
REACTIVITY
REACTORS
RESEARCH REACTORS
THERMAL NEUTRONS
Theoretical Calculations
Thermal Annulus
U235
U238
URANIUM
URANIUM 235
URANIUM 238
WATER MODERATOR
ZONES
ZPR-5