A Simplified Theory of Pile Noise

Cohn, C.E.

doi:10.13182/nse60-4

Cited by 99 publications

(31 citation statements)

References 5 publications

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“…The second uncorrelated term is the white noise component referred to as chamber noise [33][34][35]. The third term is the uncorrelated deltafunction peaks at the multiple of pulse repetition frequency.…”

Section: Power Spectral Density For Neutron Detectionmentioning

confidence: 99%

Power spectral analysis for a thermal subcritical reactor system driven by a pulsed 14 MeV neutron source

Sakon

Hashimoto

Sugiyama

et al. 2013

Journal of Nuclear Science and Technology

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A series of power spectral analyses for a thermal subcritical reactor system driven by a pulsed 14 MeV neutron source was carried out at Kyoto University Critical Assembly (KUCA), to determine the promptneutron decay constant of the accelerator-driven system (ADS). The cross-power spectral density between time-sequence signal data of two neutron detectors was composed of a familiar continuous reactor noise component and many delta-function-like peaks at the integral multiple of pulse repetition frequency. The prompt-neutron decay constant inferred from the reactor noise component of the cross-power spectral density was consistent with that obtained by a pulsed neutron experiment. However, the reactor noise component of the auto-power spectral density of each detector was hidden by a white chamber noise in the higher-frequency range and this feature resulted in a considerable underestimation of the decay constant. For several runs with a low pulse-repetition frequency, furthermore, we attempted to infer the decay constant from point data of the delta-function-like peaks. The analysis for a run under a slightly subcritical state resulted in the consistent decay constant; however, those for other runs under significantly subcritical states underestimated the decay constant. Considering the contribution of a spatially higher mode to the point data, the above underestimation was solved to obtain the consistent decay constant. While the Feynman-α formula for a pulsed neutron source is too complicated to be fitted directly to variance-to-mean ratio data, the present analysis on frequency domain is much simpler and the conventional formula based on the first-order reactor transfer function is available for fitting to power spectral density data.

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Section: Power Spectral Density For Neutron Detectionmentioning

confidence: 99%

Power spectral analysis for a thermal subcritical reactor system driven by a pulsed 14 MeV neutron source

Sakon

Hashimoto

Sugiyama

et al. 2013

Journal of Nuclear Science and Technology

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“…and 1 1 From above equations, the total fission rate can be expressed by Number of total fission or (4) P: Power in W*.…”

Section: Principle Of Measurementmentioning

confidence: 99%

A Method for Measuring Absolute Reactor Power through Neutron Fluctuation

Suzuki

1966

J. Nucl. Sci. Technol.

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A new principle is presented for obtaining absolute reactor power by processing the random fluctuation of neutron flux based on the stochastic nature of nuclear reactions. The required combination of instruments to carry out experiments is described, and experimental results o!Jtained in a swimming pool reactor are reported. The power spectral density of the output current of an ion chamber located near the reactor core is determined by reactor kinetic parameters such as delayed neutron yield, life time, iJ (mean number of neutrons generated per fission) and counter efficiency as well as by the total number of neutrons in the core, which is a measure of absolute power.Using either logarithmic amplifier or reactivity meter, absolute reactor power can be measured without any inlormation about detector efficiency. This method has such merits as easiness and simplicity in operation, ability to measure absolute power in the range 0.01~100 W where other methods are inapplicable, and negligible effect of changes in core configuration or in detector position.The results of actual reactor experiments with this method proved to agree fairly well with those of absolute measurement hy gold foil activation.

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“…Equations (2.-4), (2)(3)(4)(5), and (2)(3)(4)(5)(6) are obtained. (2)(3)(4), (2)(3)(4)(5), and (2-6) as·…”

Section: Variance Ofthe Count-rate Indicationmentioning

confidence: 99%

“…(2-20) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) For a signal composed of the linear superposition of randomly-arriving pulses, as the product of count rate and pulse width becomes large with respect to unity, the amplitude distribution of the signal approaches a normal distribution; also, the average number of times per ~econd that the signal crosses the value ST with positive slope is given( 1 ) approximately by where f 2 is the frequency of the upper half-power point of the power spectral density of the signal.…”

Section: Probability Of False Trip From the Count-rate Indicationmentioning

confidence: 99%