Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Experimental studies of temperature pulsations during the process of mixing non¬isothermal coolant flows in nuclear reactor equipment components

6/24/2019 2019 - #02 Thermal physics and thermal hydraulics

Dmitriev S.M. Mamaev A.V. Ryazapov R.R. Sobornov A.E. Kotin A.V. Bescherov D.E. Bolshuhin D.E.

DOI: https://doi.org/10.26583/npe.2019.2.10

UDC: 621.039

One of the most important scientific and technical tasks of the nuclear power industry is to ensure the reactor equipment life and reliability under random temperature pulsations. High-intensity temperature pulsations appear during the process of mixing non-isothermal coolant flows. Coolant thermal pulsations cause corresponding, sometimes very significant, fluctuations in the temperature stresses of the heat-exchange surface metal, which, added to static loads, can lead to fatigue failure of equipment components.

The purpose of this work was to conduct an experimental study of the temperature and stress-strain states of a pipe sample under the influence of local stochastic thermal pulsations caused by the mixing of single-phase heat coolant flows.

To solve the set problems, an experimental section was created, which made it possible to simulate the process of mixing non-isothermal coolant flows accompanied by significant temperature pulsations. The design of the experimental section allowed us to study the thermohydraulic and life characteristics of pipe samples made of austenitic steel (60Ч5 mm). Some tools, based on pipe sample, have been developed for measuring the pipe sample stress-strain state and the coolant flow temperature field in the zone of mixing single-phase media with different temperatures. The measuring tools are equipped with microthermocouples and strain gauges.

As a result of the research, we obtained experimental data on temperature pulsations, time-averaged temperature profiles of the coolant flow in the mixing zone, statistical and spectral-correlation characteristics of thermal pulsations. Based on the results of measuring the relative deformations, the values of fatigue stresses in the mixing zone were calculated.

In addition, some devices and methods were elaborated to measure the temperature and stress-strain states of a pipe sample under the influence of local stochastic thermal pulsations. The developed experimental section provided thermal-power loading of the metal surface at a high level of alternating stress amplitudes causing rapid rates of damage accumulation. The results are included in the database to verify the method for assessing the fatigue life of structural materials for nuclear power plants as applied to austenitic steel 12X18H10T under the influence of random thermal cyclic loads.


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equipment life temperature pulsations coolant temperature field thermal fatigue stress-strain state