Main Basic information of the centre Certification rus/eng
Â-213

      The test facility is designed for investigation of thermo-hydraulic instability in the vertical parallel steam-generating channels. According to its purpose, the test facility is called DNK (Russian acronym for «Two-phase Instability in the Channel). The coolant, used in the test facility, is water. The object under investigation is the core simulator consisting of two electrically heated channels, connected by headers at the inlet and outlet. The core simulator is demountable. The rest of the components of the test facility are designed for maintaining the prescribed boundary conditions at the core simulator inlet and outlet.
      Collection and processing of the information about the test facility parameters are automated. The test facility control is manual, remote.

Purpose of the DNK test facility and main lines of experimental research

      The DNA test facility was created for the experimental studies under a contract with KAERI (Korea Atomic Energy Research Institute) for «Investigation of instability of two-phase flow in vertical boiling channels».
      During the experiments, the following parameters are measured and recorded at the core simulator:

  • inlet and outlet pressure;
  • pressure differentials at the characteristic elements;
  • flow inlet and outlet temperatures, flow temperatures at the inlet and outlet of the heated channels;
  • wall temperature of the heating elements used in the steam-generating channels;
  • mass flow at the inlet and within the steam gene rating channels;
  • electric power supplied to each steam generating channel.

      To carry out the experimental investigations, the following types of core simulators were developed:

  1. Three core simulators of the same type with the steel tubes of the 8 mm inner diameter as channels.
    Each steam-generating channel includes a non-heated inlet section, a heated section, and a non-heated outlet section. Electrical heating is achieved by means of passing electrical current through the wall of the heated section. The channels of different core simulators differ in axial heat generation profiles (even and cosine) and in lengths of the non-heated outlet sections. At the inlet and outlet of the channels, replaceable orifice plates are installed.
  2. The core simulator each channel of which simulates a fragment of the new KAERI reactor core. As described in the above design, each channel includes a non-heated inlet section, heated section and non-heated outlet section. Electrical heating is achieved by means of passing electrical current through fuel simulators. At the inlet of the channel, replaceable orifice plates are installed.

Main parameters of the testbed:
inlet pressure, MPa — 6–17;
inlet flow-rate, kg/sec — 0,005–1,2;
heat generation in the channel, kW — 0–380;
inlet temperature, °Ń — 120–340.
 
Layout of the tested section
 
     

  
Results

      The experiments aimed at determination of the thermo-hydraulic stability boundaries for all types of the manufactured core simulators. The experiments were followed by the calculations. A computer code developed by FSUE «EREC» was involved in the calculation of stability boundaries. The code enables to analyze stabilities of the linearized combined equations with description of dynamics of thermohydraulic processes proceeding in identical parallel boiling channels.
      Now the test facility is in operating condition. The potential for the test facility ensures a study of thermal and pressure drop characteristics of reactor-plant models as follows:

  • instability of two-phase flow in the vertical boiling channels;
  • heat-exchange crisis in the fuel channel models;
  • hydraulic resistance of the design elements.