Dynamic subcriticality measurements using the sup 252 Cf-source-driven noise analysis method

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Nuclear Science and Engineering; (United States)

OSTI ID:6365093

Mihalczo, J T; Blakeman, E D; Ragan, G E; Johnson, E B ^[1]; Hachiya, Y ^[2]

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1. Oak Ridge National Lab., TN (United States). Instrumentation and Controls Div.
2. Power Reactor and Nuclear Fuel Development Corp., Tokyo (Japan)

This paper reports on dynamic measurements of the subcritical neutron multiplication factor K{sub eff} using the {sup 252}Cf-source-driven neutron noise analysis method performed for an unreflected 25.1-cm-i.d. cylindrical tank containing aqueous uranyl nitrate as the solution height changed at rates of 1 to 23 cm/min, with corresponding changes in k{sub eff} from 4 {times} 10 {sub {minus} 4} to 0.01/s. These experiments, which were the first test of the method to measure k{sub eff} while it is changing, showed the following: this method has the capability to measure subcriticality for a multiplying system to a k{sub eff} as low as 0.30; experimental k{sub eff} values can be obtained from the ratio of spectral densities with as little as 6 s of data accumulation and a small fraction of a second analysis time while the solution tank is drained from a height of 29.5 to 6.5 cm in {approx} 60 s, with corresponding changes in k{sub eff} from 0.95 to 0.30; the measured k{sub eff} values obtained do not depend on the speed at which the solution height is changed or whether it is filling or draining; the results of the dynamic measurements agreed with the static measurements; where static measurements were practical (limited to k{sub eff} down to {approx} 0.5 by detection efficiency) with {sup 3} He proportional counters sensitive to leakage neutrons only, the results agreed with those from measurements with scintillation detectors sensitive to gamma rays and neutrons escaping from the system; as in previous experiments the ratios of spectral densities at low frequency were used successfully to obtain k{sub eff} values using a modified point kinetics interpretation of the data; the neutron multiplication factors from independent measurements using the break frequency noise analysis method agree with the value of k{sub eff} from the measured ratios of spectral densities of k{sub eff} values of 0.65.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6365093
• Journal Information: Nuclear Science and Engineering; (United States), Journal Name: Nuclear Science and Engineering; (United States) Vol. 104:4; ISSN 0029-5639; ISSN NSENA
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100 -- Nuclear Reactor Technology-- Theory & Calculation
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
ACTINIDE COMPOUNDS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BARYONS
CALIFORNIUM 252
CALIFORNIUM ISOTOPES
COMPUTER CODES
DESIGN
DYNAMIC LOADS
ELEMENTARY PARTICLES
EVEN-EVEN NUCLEI
FERMIONS
FISSION NEUTRONS
HADRONS
HEAVY NUCLEI
ISOTOPES
K CODES
MEASURING INSTRUMENTS
MEASURING METHODS
MONTE CARLO METHOD
MULTIPLICATION FACTORS
NEUTRON DETECTORS
NEUTRON LEAKAGE
NEUTRONS
NITRATES
NITROGEN COMPOUNDS
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
NUCLEI
NUCLEONS
OXYGEN COMPOUNDS
POWER PLANTS
PROPORTIONAL COUNTERS
RADIATION DETECTORS
RADIOISOTOPES
REACTOR ACCIDENTS
REACTOR NOISE
REACTOR SAFETY EXPERIMENTS
SPONTANEOUS FISSION RADIOISOTOPES
SUBCRITICALITY
THERMAL POWER PLANTS
URANIUM COMPOUNDS
URANYL COMPOUNDS
URANYL NITRATES
YEARS LIVING RADIOISOTOPES