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The paper considers the statistics of intervals between neutron registration by the detecting system based on fission ionization chamber KHT31-1, statistics of intervals between noise signal impulses in absence of neutrons and possibility to distinguish neutron flows from different sources. It is shown that spurious noise signal from alpha decay of 234U in a radiator of the ionization chamber KHT31-1 can be used as a reference signal in measuring neutron fluxes from different sources. The analysis of long-term continuous sets of measurements is taken as a basis of mathematical treatment.

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Three-hour and daily mean measurements of the module of an average speed and wind gusts were analyzed over 2001-2006 in the Chernobyl NPP region using wavelet analysis and the method of the Herst normalized range. Diurnal and seasonal fluctuations are revealed, the periodicity of 8, 16, and 60 days is not well-pronounced. The derived Herst high-value coefficients (~0.7-0.8) against the background of well-pronounced seasonal and other fluctuations of an average wind speed are indicative of the fact that its temporal variability is far from being random. The analysis is performed to predict the concentration of radioactive aerosols released from the Ukrytie object (the damaged unit 4 of the ChNPP), whose changes correlate with the wind speed.

The data of observations since 1951 in the upper part of the Southern Bug River basin in the west of Ukraine are analyzed. The results indicate that the climate change occurring on Earth disrupts the regular cyclicity of groundwater flow indicators. The identified 7–8-year groundwater level and flow to the river cyclicity correlates well with the air temperature, precipitation and river runoff cyclicity. The noted groundwater cyclicity appears with some delay after the establishment of the 8-year air temperature cyclicity observed since 1969. The manifestation of a 7–8-year cycle depends on the groundwater table (GWT) depth. For shallow groundwater (1.0–2.5 m), such rhythms have been observed since 1975, and for deeper levels, since 1989, which is recognized as the year of the beginning of the climate changes. Moreover, 7–8-year rhythms in the fluctuation of groundwater parameters are characteristic of mainly high-water periods of their multiyear regime, and during the low-flow phase is significantly weakened. During 2011–2014, the groundwater levels abnormally decreased and the 8-year cycles were replaced with 5-year ones. The influence of air temperature on the groundwater regime exceeds the role of other factors. Wavelet analysis was used as the main method of periodicity observation. Gaussian and Morlet wavelets provide the visualization of pronounced periodicities of data. Using multiple correlation analysis, it was confirmed that temperature has become the dominant impact factor on the groundwater (GWT 1.5–4.0 m) regime in recent decades.