The analysis of at-power neutron flux noise in the frequency range of vibrating reactor structures

Wach, D.

doi:10.1016/0306-4549(75)90038-9

Cited by 13 publications

(2 citation statements)

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“…In PARR-1, the temperature feedback affect may be neglected at low power. The PSDs of reactivity and neutron noise in the core due to inlet temperature fluctuations are given by the relations [7] (1) (2) where PSD of core inlet temperature; transfer function relating the fluctuation in the inlet coolant temperature to the core-averaged coolant temperature fluctuations; coolant temperature coefficients of reactivity relating the average coolant temperature fluctuations to the reactivity fluctuations; zero-power transfer function relating the reactivity variations to the variations in neutron density, or reactor power. The effect of fuel temperature fluctuations on neutron noise is very small and is neglected.…”

Section: Reactivity Effect Of Coolant Temperature Fluctuationsmentioning

confidence: 99%

“…The analysis of reactor noise requires the knowledge of various noise sources in the reactor that affect the reactivity of the system. The mechanical vibration of the fuel elements or control rods has been identified as one major source of neutron noise, and noise analysis can be used to detect such phenomenon [2]. The fluctuations in coolant temperature, flow and pressure also contribute to the reactivity and neutron noise in nuclear power plants.…”

Section: Introductionmentioning

confidence: 99%

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Detection of Flow-Induced Vibration of Reactor Internals by Neutron Noise Analysis

Ansari

Haroon

Sheikh

et al. 2008

IEEE Trans. Nucl. Sci.

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Flow-induced vibrations of reactor core components have been a major cause of failure of reactor internals in many nuclear power plants. To address this issue international standards (viz., ASME-OM-05) require monitoring of structural integrity of reactor core in nuclear power plants. A reactor internals vibration monitoring system (IVMS) has been developed for nuclear power plant surveillance. The system detects the core barrel motion and flow-induced vibrations of reactor internals by analyzing the inherent fluctuations (reactor noise) present in the neutron flux signals from ex-core neutron detectors. Before application of the IVMS in nuclear power plants the system hardware and methodology/software has been extensively tested on the research reactor through a series of reactor noise measurements. In the noise measurements the neutron flux signals were correlated with the signals from vibration sensors mounted on reactor structure and control rods drive mechanisms. The frequency spectra of reactor power signals obtained with IVMS had shown small oscillations in the neutron flux signals at well-defined frequencies. There was a strong correlation of these fluctuations with the establishment of coolant flow through the core. With the help of elaborate experiments using the IVMS the cause of oscillations in neutron flux signals was attributed to the flow-induced vibrations of control rods, and the particular vibrating control rod was identified. The magnitude of the displacement of vibrating control rod was calculated from the measured power spectral density of neutron power signals. It has been shown that ex-core neutron noise measurements are more sensitive in determining the dynamic behavior of reactor internals than the vibration sensors mounted at remote, out-of-the core locations.

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Section: Reactivity Effect Of Coolant Temperature Fluctuationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%