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International Conference on Innovative Applied Energy    

E-Proceedings ISBN: 978-1-912532-05-6

St Cross College, University of Oxford, United Kingdom



Experimental studies of the initial section in the channel simulator of a heat-releasing element cell



E.F. Avdeev, P. Hong Tran and V.O. Smirnova

Studgorodok, Obninsk, Russia



Paper Abstract

The nominal value of the coolant flow rate through the active zone is determined by the thermal power of the reactor. The actual flow rate may differ from the nominal value when the pressure loss in the fuel assembly is wrongly determined. If the actual pressure loss is underestimated, the temperature of the coolant at the outlet from the fuel assembly in the upper collector does not reach the design values (will be understated).
The main content of the report is devoted to the experimental proof of the underestimated calculated values of the pressure loss along the TVS cell channels, while ignoring the features of the increased resistances at the initial sections of the channels. The work is of practical importance for active zones with short-length heat-releasing elements.
The study had provided complete measurement results of the velocity field and the pressure loss of the initial section in the channel of the scaled-up close-packed model of the heat-releasing element cell. It also provides estimates of pressure losses based on the boundary layer calculation on the basis of the Theodore Karman integral and their comparison with the experimental ones. A dependence was found to determine the flow rate from the measured maximum velocity in the heat-releasing element cell.

The proposed dependence for determining the flow rates in TVS cell channels from the measured maximum velocity is of practical importance in experiments, usually with a limited number of fuel elements. The main results of the work are indicated in the conclusion of the full report and are summarized as follows:
• The length of the initial section in the channel of the TVEL cell is much shorter than in the round tube
• Pressure losses in the initial section can not be calculated via formulas for stabilized flow
• Pressure losses in the initial section can be estimated on the basis of an approximate calculation of the boundary layer. 

Paper Keywords
Heat-releasing element cell, hydraulic diameter, grid relative step of fuel element, initial channel section, volume flow, average speed, frictional stress, braking pressure, static pressure, turbulent flow, stabilised area, tight packing of heat-releasing cells, maximum speed, average speed.
Corresponding author Biography
Smirnova Victoria Olegovna is a 5th-year student at the Ins9tute of Nuclear Power Engineering of the
Na9onal Research University MEPhI. She is engaged in research in the field of nuclear propulsion control
and management of physical processes.

The International Conference on Innovative Applied Energy (IAPE’18)