A System of Obtaining and Reducing Neutron Flux Data from a Critical Assembly

Journal Article · Tue Jul 01 04:00:00 EDT 1958 · Nuclear Science and Engineering

OSTI ID:4318863

Morewitz, H. A. ^[1]; Valentine, R. F. ^[1]

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1. Westinghouse Electric Corp., Pittsburgh, PA (United States)

Some new techniques have been applied in the determination of relative neutron fluxes in water moderated critical assemblies. Alloy wires of Mn--Fe, In- -Al, Au--Al, and U--Zr have been prepared with a high degree of uniformity between individual samples of a given material. Beta activation of these wires is measured by thin scintillation crystals in conjunction with specially stabilized electronics. This procedure results in good "plateaus" of counting rate vs. photomultiplier voltage, discriminator setting, and amplifier gain. The counting time of a wire is controlled by a decaying sample of the activated material. Thus, as the counting continues, the counting interval becomes progressively longer, providing automatic decay correction of the data. Several benefits are obtained from this method. The statistics of counting for a wire of a given activation level are independent of the time of counting; nonuniform decay (e.g., mixed fission product decay) is handled with the same facility as simple exponential decay. Automatic sample changers are used which make possible the counting of larger numbers of samples (approximately 1500 per day) with a minimum of personnel. These changers have been so adjusted that good precision in positioning is maintained. The automatic features of the counting system permit a rapid qualitative evaluation of the data. An error analysis has been made which indicates an experimental counting error (exclusive of statistical error due to decay) of approximately 0.8%. This error, when combined with the appropriate statistical error, has been applied to improve the use of computer codes in obtaining accurate least square fits of theoretical curves to the experimental data.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• NSA Number: NSA-12-014272
• OSTI ID: 4318863
• Journal Information: Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Vol. 4; ISSN 0029-5639
• Publisher: Taylor & Francis
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTIVATION
ALUMINUM ALLOYS
AMPLIFIERS
BETA DECAY
BETA DETECTION
CIRCUITS
CRITICAL ASSEMBLIES
DECAY
DIAGRAMS
EFFICIENCY
ELECTRONICS
EQUATIONS
ERRORS
FISSION PRODUCTS
GOLD ALLOYS
IMPURITIES
INDIUM ALLOYS
IRON ALLOYS
MANGANESE ALLOYS
MEASURED VALUES
NEUTRON FLUX
Nuclear Criticality Safety Program (NCSP)
PERSONNEL
PHOTOMULTIPLIERS
PROGRAMMING
PULSE ANALYZERS
SCINTILLATION COUNTERS
SERVOMECHANISMS
STATISTICS
URANIUM ALLOYS
WATER MODERATOR
WIRES
ZIRCONIUM ALLOYS