ZPR-3 Assemblies 48, 48A, and 48B: The Study of a Dilute Plutonium-fueled Assembly and Its Variants

Technical Report · Tue Dec 01 00:00:00 EST 1970

DOI:https://doi.org/10.2172/4004283· OSTI ID:4004283

Broomfield, A. M. ^[1]; Hess, A. L. ^[2]; Amundson, P. I. ^[2]; Baird, Q. L. ^[3]; Bennett, E. F. ^[2]; Davey, W. G. ^[2]; Gasidlo, J. M. ^[2]; Keeney, W. P. ^[2]; Long, J. K. ^[2]; McVean, R. L. ^[2]

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1. UK Atomic Energy Authority (UKAEA), Winfrith (United Kingdom)
2. Argonne National Lab. (ANL), Argonne, IL (United States)
3. Battelle Pacific Northwest Labs., Richland, WA (United States)

ZPR-3 Assembly 48 and its variants were relatively simple and small plutonium-fueled fast critical systems, which nevertheless possessed spectra and other characteristics related to the large, liquid-metal-cooled fast breeder reactors envisaged for power production. Composition simplicity offered the best chance for accurate postanalyses of the experiments. However, to relate to the projected fast power reactors, the core necessarily included plutonium, uranium, and sodium, while the requirement of a soft neutron spectrum dictated the inclusion of a moderator, in this case graphite. All the cores therefore were composed with plates of plutonium diluted with plates of depleted uranium, sodium, and graphite, in addition to the necessary steel drawers and matrix tubes. In Assembly 48, the atomic ratio of uranium to plutonium in the core was approximately 4:1, with the ²⁴⁰Pu isotopic fraction of 6%, and the blanket was 12 in. of depleted uranium. Assembly 48A had the same core composition, except that part of the radial blanket was replaced by an Inconel reflector. Worths of simulated B₄C control rods were measured in the Inconel reflector. In Assembly 48B, the core contained a small central zone where the ²⁴⁰Pu isotopic content in the plutonium was raised to an average of approximately 17%. The program of Assembly 48 experiments described in this report includes the measurements of critical masses, central fission ratios, central reactivity coefficients, heterogeneity effects, sodium-voiding worth, neutron spectrum, ²³⁸U and plutonium Doppler effect, material-worth and reaction-rate traverses, and foil activations. In Assembly 48A, attention was confined to the worths of B₄C rods and their influence on reaction rates and material worths. In Assembly 48B, a limited selection of the Assembly 48 measurements was repeated, including the worths of sodium-voiding and the Doppler effect in ²³⁸U.

• Research Organization: Argonne National Lab. (ANL), Argonne, 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-31-109-ENG-38
• NSA Number: NSA-25-028752
• OSTI ID: 4004283
• Report Number(s): ANL-7759
• Resource Relation: Other Information: UNCL. Orig. Receipt Date: 31-DEC-71
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTIVATION
BORON CARBIDES
CAPTURE
CONFIGURATION
CONTROL ROD WORTH
CRITICAL MASS
DOPPLER REACTIVITY
FAST REACTORS
FISSION
FOILS
NEUTRON SPECTRA
NEUTRONS
NUCLEAR REACTIONS
REACTIVITY WORTHS
REACTOR CORE
REACTOR KINETICS
SODIUM
VOID COEFFICIENT
ZPR-3
Nuclear Criticality Safety Program (NCSP)
Fast Breeder Reactor
Atomic Ratio
240Pu
238U
Reactivity Coefficient
Doppler Effect
Reaction Rate
Material Worth