Logistic Approximation of the Calibration Characteristics

3/27/2026 2026 - #01 Physics and technology of nuclear reactors

Yuferov A.G.

https://doi.org/10.26583/npe.2026.1.04

The paper considers the problem of approximating the calibration characteristic of a nuclear reactor control element by means of a two-parameter logistic curve. Such a choice of the approximating function reduces the computational costs of predicting reactivity when changing the position of the control element, provides the required accuracy of the forecast, and allows characterizing the full efficiency of the element and its dynamics by only two parameters that determine the logistic curve. The first parameter, the upper asymptote of this curve, corresponds to the full efficiency of the control element. In the case of an objectively adequate logistic approximation, any three equidistant measurements of the experimental calibration characteristic are sufficient to estimate this parameter. The second parameter of the logistic curve has the meaning of the relative rate of change of reactivity. The fundamental possibility of obtaining a good logistic approximation for experimental calibration characteristics is shown using the example of the integral characteristic of a group of automatic control cassettes of the WWER-440 reactor. The results of the dispersion analysis confirm the adequate reproduction of this characteristic by the logistic model – the determination coefficient is almost equal to one.

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egulatory authority calibration characteristics logistic approximation reactivity

Link for citing the article: Yuferov A.G. Logistic Approximation of the Calibration Characteristics. Izvestiya vuzov. Yadernaya Energetika. 2026, no. 1, pp. 46-51; DOI: https://doi.org/10.26583/npe.2026.1.04 (in Russian).