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The possibilities of using thermography for quantitative studies of the frequency characteristics of the nonisothermal water pulsations near the vessel walls transparent to infrared radiation are analyzed. Thermographic studies of the temperature dynamics in the contact zone of a nonisothermal liquid with the wall were performed using simple models. Frequencies of temperature fluctuations at the inner surface of the vessel through the wall transparent to infrared radiation were measured using a thermal imager with accurate focusing of the lens. Spectral curves of the fluctuations were constructed with the use of a Fourier transform. It is shown that Kolmogorov spectra (−5/3 law) are present in the nonisothermal flow in a T-junction channel, allowing the process to be characterized as developed turbulence of the water flow in the region of the boundary layer adjacent to the window.

Equipping new-generation nuclear power plants with passive means for controlling unanticipated accidents is one of the most promising directions for increasing safety, which is being implemented in the AES-2006 design for the site of the Leningradskaya nuclear power plant. An urgent problem is to obtain experimental validation of the passive system for removing heat from the protective envelope during unanticipated accidents with loss of coolant from the first loop in the case where the active systems fail. A particularity of the system is its state of constant readiness. The system functions with natural circulation of the coolant in both loops. Considering the importance of the passive heat removal system for ensuring the localizing properties of the protective envelope, OKBM Afrikantov has developed a large-scale stand and performed experimental investigations on validation of the effectiveness and serviceability of the cooling loop of a passive system for removing heat from the protective envelope.One direction for increasing the safety of nuclear power plants is to adopt passive systems which guarantee that the required functions will be executed during a loss of all electric power sources at a plant. This increases the stability of the nuclear facility with respect to not only the failure of power supplies but also possible extreme actions. The AES-2006 design of the safety systems for the site of the Leningradskaya nuclear power plant provides active as well as passive systems which do not require power sources to operate. These systems include a passive system for removing heat from the protective envelope during accidents with loss of coolant in the first loop and failure of active safety systems. During normal operation of a nuclear power plant, the system is in a state of constant readiness. During accidents in which steam enters the protective envelope and the temperature inside the envelope increases, heat is removed to exchanger-condensers by natural convection and condensation. Natural circulation of coolant arises in the cooling loop of the passive heat removal system; heat is removed to the final absorber into the atmosphere.When such systems are being designed, there arise problems due to the low hydrodynamic stability of the flow of boiling coolant in the cooling loop of the passive heat removal system under low pressure. Computational and experimental

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