A Portable Measurement System for Subcriticality Measurements by the CF-Source-Driven Neutron Noise Analysis Method

Conference · Wed Oct 21 04:00:00 EDT 1987

DOI:https://doi.org/10.1109/23.12859· OSTI ID:6219178

Mihalczo, J. T. ^[1]; Ragan, G. E. ^[1]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Instrumentation and Controls Division

A portable system has been assembled that is capable of measuring the subcriticality of fissile materials using the ²⁵²CF-source-driven neutron noise analysis method. The measurement system consists of a parallel-plate ionization chamber containing ²⁵²CF, two ³He proportional counters with their associated electronics, and a small computer containing anti-aliasing filters and A/D convertors. The system Fourier analyzes the digitized data and forms the appropriate auto and cross-power spectral densities. These spectra are used to form a ratio of spectral densities, G₁₂ G₁₃/G₁₁ G₂₃, where 1 refers to the ionization chamber, and 2 and 3 refer to the /sup 3/He counters, from which subcriticality can be determined. The chamber and detectors are located appropriately near the fissile material. The system is capable of sampling signals at rates of up to 80 kHz and processing these data at rates of 2 kHz to form the appropriate spectra. The presently configured system is a two-channel system, hence the measurement of G₁₂, G₁₃, and G₂₃ must be done sequentially before the ratio of spectral densities is obtained. Future improvements of the system will allow simultaneous measurement of all spectra and will further reduce size, thereby enhancing portability. This measurement system can provide reliable, cost effective, and convenient determination of the subcriticality of a wide variety of fissile materials and moderators.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Instrumentation and Controls Division
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6219178
• Report Number(s): CONF-871005-1; ON: DE87008592
• Country of Publication: United States
• Language: English

Related Subjects

440103* -- Radiation Instrumentation-- Nuclear Spectroscopic Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
Analog-to-Digital (A/D)
Auto-Power Spectral Density (APSD)
BARYONS
CALIFORNIUM 252
CALIFORNIUM ISOTOPES
Cross-Power Spectral Density (CPSD)
ELEMENTARY PARTICLES
EQUIPMENT
EVEN-EVEN NUCLEI
FERMIONS
FISSILE MATERIALS
FISSIONABLE MATERIALS
FUNCTIONS
Fissile System
Fourier Analyzer
HADRONS
HEAVY NUCLEI
IONIZATION CHAMBERS
ISOTOPES
MATERIALS
MEASURING INSTRUMENTS
MODERATORS
NEUTRON SPECTROSCOPY
NEUTRONS
NOISE
NUCLEI
NUCLEONS
Neutron Multiplication Factor
Nuclear Criticality Safety Program (NCSP)
PORTABLE EQUIPMENT
PROPORTIONAL COUNTERS
RADIATION DETECTORS
RADIOISOTOPES
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
SPECTROSCOPY
SUBCRITICALITY
YEARS LIVING RADIOISOTOPES