Anatomy of a controversy: Application of the Langevin technique to the analysis of the Californium-252 Source-Driven Noise Analysis method for subcriticality determination

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5898069

Stolle, A M

The expressions for the power spectral density of the noise equivalent sources have been calculated explicitly for the (a) stochastic transport equation, (b) the one-speed transport equaton, (c) the one-speed P{sub 1} equations, (d) the one-speed diffusion equation and (e) the point kinetic equation. The stochastic nature of Fick's law in (d) has been emphasized. The Langevin technique has been applied at various levels of approximation to the interpretation of the Californium-252 Source-Driven Noise Analysis (CSDNA) experiment for determining the reactivity in subcritical media. The origin of the controversy surrounding this method has been explained. The foundations of the CSDNA method as a viable experimental technique to infer subcriticality from a measured ratio of power spectral densities of the outputs of two neutron detectors and a third external source detector has been examined by solving the one-speed stochastic diffusion equation for a point external Californium-252 source and two detectors in an infinite medium. The expression relating reactivity to the measured ratio of PSDs was found to depend implicitly on k itself. Through a numerical analysis fo this expression, the authors have demonstrated that for a colinear detector-source-detector configuration for neutron detectors far from the source, the expression for the subcritical multiplication factor becomes essentially insensitive to k, hence, demonstrating some possibility for the viability of this technique. However, under more realistic experimental conditions, i.e., for finite systems in which diffusion theroy is not applicable, the measurement of the subcritical multiplication factor from a single measured ratio of PSDs, without extensive transport calculations, remains doubtful.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 5898069
• Country of Publication: United States
• Language: English

Related Subjects

440101* -- Radiation Instrumentation-- General Detectors or Monitors & Radiometric Instruments
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CALIFORNIUM 252
CALIFORNIUM ISOTOPES
DATA ANALYSIS
EQUATIONS
EVEN-EVEN NUCLEI
EXPERIMENTAL REACTORS
FICK LAWS
FUNCTIONS
HEAVY NUCLEI
IN CORE INSTRUMENTS
ISOTOPES
LANGEVIN EQUATION
MEASURING INSTRUMENTS
MONITORING
NEUTRON DETECTORS
NEUTRON SOURCES
NOISE THERMOMETERS
NUCLEI
PARTICLE SOURCES
POWER DENSITY
RADIATION DETECTORS
RADIATION SOURCES
RADIOISOTOPES
REACTIVITY
REACTOR INSTRUMENTATION
REACTORS
RESEARCH AND TEST REACTORS
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
SPONTANEOUS FISSION RADIOISOTOPES
SUBCRITICAL ASSEMBLIES
SUBCRITICALITY
THERMOMETERS
YEARS LIVING RADIOISOTOPES