Publication

Processus aléatoires dans un réacteur nucléaire contrôlé par un dispositif de réglage

1972
Theses

Abstract

A stochastic model of a reactor with a control rod is studied here. By assimilating populations of neutrons, of precursors and of absorbing atoms associated with control rod displacements to markovian random variables, the Chapman-Kolmogorov equation is established. Using Fokker-Planck and Langevin approximations, one obtains the noise spectral density P(f) of the control rod in terms of reactivity. Applied to a large bandwidth control system, commanded by a low efficient detector, the mode1 permits to obtain, from an experimental analysis of P(f), the value of αc = β/l where β is the total fraction of delayed neutrons and l, the average life time of neutrons.

Official source

https://infoscience.epfl.ch/entities/publication/51bfc223-ad12-40cd-be1f-d7cd9e797b59

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1972
Theses

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/51bfc223-ad12-40cd-be1f-d7cd9e797b59

About this result

Related concepts (24)

Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics and central to thermodynamics. Any conductor with electrical resistance will generate thermal noise inherently. The final elimination of thermal noise in electronics can only be achieved cryogenically, and even then quantum noise would remain inherent. Electronic noise is a common component of noise in signal processing.

Spectral density

The power spectrum of a time series describes the distribution of power into frequency components composing that signal. According to Fourier analysis, any physical signal can be decomposed into a number of discrete frequencies, or a spectrum of frequencies over a continuous range. The statistical average of a certain signal or sort of signal (including noise) as analyzed in terms of its frequency content, is called its spectrum.

Carrier-to-noise ratio

In telecommunications, the carrier-to-noise ratio, often written CNR or C/N, is the signal-to-noise ratio (SNR) of a modulated signal. The term is used to distinguish the CNR of the radio frequency passband signal from the SNR of an analog base band message signal after demodulation. For example, with FM radio, the strength of the 100 MHz carrier with modulations would be considered for CNR, whereas the audio frequency analogue message signal would be for SNR; in each case, compared to the apparent noise.

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