Experimental studies of temperature pulsations during the process of mixing non¬isothermal coolant flows in nuclear reactor equipment components
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.
- Abib E., Bergholz S., Rudolph J. German experiences in local fatigue monitoring. International Journal for Nuclear Power. 2013, v. 58, pp. 284-289.
- Chapuliot S., Gourdin C., Payen T., Magnaud J.P., Monavon A. Hydro-thermal-mechanical analysis of thermal fatigue in a mixing tee. Nuclear Engineering and Design. 2005, v. 235, pp. 575-596.
- Faidy C. High Cycle Thermal Fatigue: Lessons Learned From Civaux Event. In: Materials Reliability Program: Second International Conference on Fatigue of Reactor Components (MRP-84), July 29-August 1, 2002, Snowbird, Utah, 2002.
- Sudakov A.V., Trofimov A.S. Pulsations of temperature and electrical equipment‘s component life. Leningrad.Energoatomizdat, 1989, 179 p. (in Russian).
- Sudakov A.V., Trofimov A.S. Voltages at temperature pulsations. Moscow. Atomizdat Publ., 1980, 64 p. (in Russian).
- Budov V.M., Dmitriev S.M. Forced heat exchangers of water cooled nuclear power unit. Moscow. Energoatomizdat Publ., 1989, 174 p. (in Russian).
- NP-054-04. Norms for Calculating the Strength of Equipment Elements and Pipelines for Ship Nuclear Steam Generating Units with Water-Cooled Reactors. Moscow. Rostekhnadzor Rossii Publ., 2004, 57 p. (in Russian).
- Jhung M.J. Assessment of thermal fatigue in mixing tee by FSI analysis. Nuclear Engineering and Technology. 2013, v. 45, pp. 99-06.
- Mahaffy J., Chung B., Dubois F., Ducros F., Graffard E., Heitsch M., Henriksson M., Komen E., Moretti F., Morii T., Mьhlbauer P., Rohde U., Scheuerer M., Smith B. L., Song C., Watanabe T., Zigh G. Best practice guidelines for the use of CFD in nuclear reactor safety applications. NEA/CSNI/R(2007)5, 2007.
- Smith, B. L. Assessment of CFD codes used in nuclear reactor safety simulations. Nuclear Engineering and Technology. 2010, v. 42, pp. 339-364.
- Smith B. L., Andreani M., Bieder U., Ducros F., Graffard E., Heitsch M., Henrikkson M., Hцhne T., Houkema M., Komen E., Mahaffy J., Menter F., Moretti F., Morii T., Mьhlbauer P., Rohde U., Scheuerer M., Song C.H., Watanabe T., Zigh G. Assessment of CFD Codes for Nuclear Reactor Safety Problems – revision 2. OECD/NEA/CSNI/R(2014) 12, 2015.
- Smith B. L., Bestion D., Hassan Y. Experiments and CFD Code Applications to Nuclear Reactor Safety (XCFD4NRS). Special Issue: Nuclear Engineering and Design. 2010, v. 240, pp. 2075-2382.
- Wakamatsu M., Nei H., Hashiguchi K. Attenuation of temperature fluctuations in thermal striping. Journal of Nuclear Science and Technology. 1995, v. 32, pp. 752-762.
- Beaufils R., Courtin. Analysis of the Father Experiment with an Engineering Method Devoted to High Cycle Thermal Fatigue. In: Proceedings of the ASME 2011 Pressure Vessels & Piping Conference (PVP 2011), July 17-21, 2011. Baltimore, Maryland, USA, 2011.
- Courtin S. High Cycle Thermal Fatigue Damage Prediction in Mixing Zones of Nuclear Power Plants: Engineering Issues Illustrated on the FATHER Case. Procedia Engineering. 2013, v. 66, pp. 240-249.
- Miyoshi K., Kamaya M., Utanohara Y., Nakamura A. An investigation of thermal stress characteristics by wall temperature measurements at a mixing tee. Nuclear Engineering and Design. 2016, v. 298, pp. 109-120.
- Braillard O., Edelin D. Advanced experimental tools designed for the assessment of the thermal load applied to the mixing tee and nozzle geometries in the PWR plant. In: Advancements in Nuclear Instrumentation, Measurement Methods and their Applications, ANIMMA 2009, June 7-10, 2009. Marseille, France, 2009.
- Chen M.S., Hsieh H.E., Ferng Y.M., Pei B.S. Experimental observations of thermal mixing characteristics in T-junction piping. Nuclear Engineering and Design. 2014, v. 276, pp. 107-114.
- Kamide H., Igarashi M., Kawashima S., Kimura N., Hayashi K. Study on mixing behavior in a tee piping and numerical analyses for evaluation of thermal striping. Nuclear Engineering and Design. 2009, v. 239. pp. 58-67.
- Dmitriev S.M., Spiridonov D.V., Vostrikov A.A., Dmitrieva T.S. Nestacionarnoe temperaturnoe sostoyanie i ocenka dolgovechnosti teploobmennoj poverhnosti parogeneriruyushchego ehlementa s dvustoronnim obogrevom. Trudy RNKT-4. 2006, v. 4, pp. 88-91 (in Russian).
- Kuschewski M. Development and application of flow measurement methods for the investigation of near-wall temperature fields. Doctoral dissertation, University of Stuttgart. 2015, No: D93.