A stochastic method for nuclear power plant diagnosis

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7126845

Perez, R B; Wood, R T

The value of using neutron noise descriptors, especially the power spectral densities (PSDs) of ex-core detectors, to monitor core barrel motion and fuel element vibrations in pressurized water reactors (PWRs) is well established. Indeed, in the mid-frequency range (1 to 20 Hz), PWR neutron noise is dominated by vibration peaks in the neutron PSD that result from the motion of reactor internals. A qualitative examination of such descriptors from a 1150 MWE Westinghouse PWR plant, re-examination of such descriptors from a 1150 MWE Westinghouse PWR plant, revealed significant changes in the plant's noise signature (PSD) as its first fuel cycle proceeded. The purpose of this work is to use a mathematical model of the interaction between small mechanical motions and the core neutronics to provide a tool for quantitative investigation of the PSD structure in the vibrational frequency range. The purpose of neutron noise analysis is to provide information on plant conditions by the study of power traces from ex-core detectors. Due to the action of the coolant flow through the core and pump induced vibrations, the core barrel, which is bolted at the top of the reactor vessel, performs a pendular motion with a natural frequency determined by the mechanical parameters and constraints of the system. In addition, external forces deform the cylindrical shape of the core barrel by inducing vibrational modes which are excited by the turbulence of the coolant flow and by the /open quotes/table-shaker/close quotes/ effect of the core barrel motion. As a result of the various mechanical motions, the detector response will vary in a manner proportional to the importance function at the location of the disturbance. 7 refs., 4 figs., 1 tab.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7126845
• Report Number(s): CONF-880557-4; ON: DE88015558
• 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
DIAGNOSTIC TECHNIQUES
FUNCTIONS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MECHANICAL VIBRATIONS
NEUTRON DETECTORS
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
PERTURBATION THEORY
POWER PLANTS
RADIATION DETECTORS
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
SPECTRAL RESPONSE
STOCHASTIC PROCESSES
THERMAL POWER PLANTS