Application of the SEFOR Critical Experiments at ZPR-3 to SEFOR

Technical Report · Wed Oct 12 04:00:00 EDT 1966

DOI:https://doi.org/10.2172/4318290· OSTI ID:4318290

Reynolds, A. B. ^[1]; Stewart, S. L. ^[1]

---

1. General Electric Co., San Jose, CA (United States)

A series of critical experiments was performed with a mockup of SEFOR at ZPR-3. Analyses of these experiments and the application of the results to the SEFOR design are discussed. Values of the critical mass were determined for 1-, 2-, and 3-segment SEFOR fuel designs in order to help establish the plutonium atom fraction in the SEFOR fuel. Reactivity effects of axial fuel expansion were measured which led to selection of the 2-segment design for SEFOR. Measurements of the reactivity worth of the radial reflector established the adequacy of the SEFOR reflector-control system. The Doppler coefficient was measured. The calculated U²³⁸ Doppler coefficient was in agreement with the experimental value; the measured Pu²³⁹ contribution to the SEFOR Doppler coefficient was near zero. It was demonstrated that the SEFOR Doppler coefficient [$T(dk/dT)$ = -0.0085] is significantly more negative than the conservative value assumed for safeguards analysis. The maximum positive reactivity due to loss of sodium was measured; the measured reactivity was small (+6¢) and close to the calculated value. The ratio of prompt-neutron lifetime to delayed-neutron fraction was measured both by the pulsed neutron technique and by noise analysis. The values measured by the two techniques were in agreement, and, for a calculated β$$_{eff}$$ of 0.0033, gave $$l$$= 0.68 μsec. Fission ratios, fission and boron traverses, and plutonium worth distributions were measured and compared with calculations.

• Research Organization: General Electric Co., San Jose, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• NSA Number: NSA-21-035695
• OSTI ID: 4318290
• Report Number(s): ANL-7320
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CRITICAL ASSEMBLIES
CRITICALITY
Critical Mass
DETERMINATION
DOPPLER REACTIVITY
Doppler Coefficient
EXPANSION
FISSION
FUELS
Fission Ratio
LOSSES
MASS
MEASUREMENT
MOCKUP
Nuclear Criticality Safety Program (NCSP)
REACTIVITY
REACTIVITY WORTHS
REFLECTORS
RESEARCH REACTORS
Reactivity
SEFOR
SODIUM
SPECTRAL SHIFT
TEMPERATURE
URANIUM 238
VELOCITY
Worth Distributions
ZPR-3