Analysis of experiments performed at University of Hannover with RELAP5/MOD2 and CATHARE codes on fluid dynamic effects in the fuel element top nozzle area during refilling and reflooding
The experimental data of flooding and CCFL in the fuel element top nozzle area collected at the University of Hannover are analyzed with RELAP5/MOD2 and CATHARE V.1.3 codes. Preliminary sensitivity calculations are performed to evaluate the influence of various parameters and code options on the results. An "a priori" rational assessment procedure is performed for those parameters non-specific in experimental data (e.g., energy loss coefficients in flow restrictions) based on single phase flow pressure drops. The reported experimental data demonstrate the complex relationships between between the physical qualities involved (film thickness, pressure drop etc.) even in a simple geometrical condition with well defined boundary conditions. In the application of the two advanced codes to the selected CCFL experiments it appears that sophisticated models do not simulate satisfactorily to the measured phenomena, when situations similar to nuclear reactors are considered (rod bundles). The work performed demonstrates that further applications to CCFL experiments of present codes do not appear to be useful. New models should be tested and implemented before any attempt to reproduce CCFL in experimental facilities by system codes. A theoretical model previously developed for a cylindrical geometry is adapted to predict the data collected with reasonable agreements for high injected liquid flow rates. The results of experimental work with detailed measurements for one single-channel test section and for multi-channel test sections are compared to some existing models, and further work is recommended.
Bibliographic Reference: EUR 12407 EN (1989) 134 pp., FS, ECU 11.25
ISBN: ISBN 92-826-1185-X
Record Number: 199010779 / Last updated on: 1994-12-01
Original language: en
Available languages: en