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Vibration identification of nuclear reactor components by statistical analysis of neutron noise

Thesis/Dissertation ·
OSTI ID:6521973
The possibility of identifying vibrating components, in a nuclear reactor core, through the use of statistical techniques was investigated. Mechanical vibrations produce neutron noise that appears as fluctuations in detector signals. Theory pertaining to the production of neutron noise is discussed. Vibrations are characterized by location and vibration trajectory parameters. Maximum-likelihood and confidence-region techniques were developed to estimate these parameters. Computer experiments were carried out using simulated detector signals for a simplified reactor model. The sensitivity of the techniques was investigated by parametrically studying the effects of noise level in the detector signal and the presence of external noise or bias in the model. The use of the Fisher information matrix, as a tool, to estimate the optimum number and pattern of detectors required in the identification process, was demonstrated. An experiment was performed utilizing the Iowa State University UTR-10 reactor to demonstrate the validity of the statistical techniques developed. A vibrating absorber, moving in one dimension, was operated in the fuel region and measurements were taken with four detectors. Detector responses, in terms of auto-power spectral densities, were calculated using a modified version of the computer code, Exterminator-2.
Research Organization:
Iowa State Univ. of Science and Technology, Ames (USA)
OSTI ID:
6521973
Country of Publication:
United States
Language:
English