The HELENA test program: description and analysis of the steady-state operation

The objective of the HELENA program is to characterize the temperature distributions (average values and fluctuations) in an helicolly coiled tube-wall cooled by an internal two-phase flow at high pressure. The dry-out zone behaviour is studied to estimate the mechanical consequencies induced by the thermal cycling occuring at the inner surface of the tube. In addition, the temperature distribution of the sodium flow, on the shell side, is also examined. Concurrently, CEA conducted the CATALINA program which is directly oriented to a thermal mechanical objective and a collaboration EDF-CEA was engaged to include common tests and actions on both programs in order to improve the knowledge of the phenomena studied. The HELENA tests started in November 1986 and lasted throughout 1987. Three tests types were performed: steady-state run tests (110), transient run tests (22) and dynamic instability run tests (6). After a presentation of the main characteristics of the mock-up and of the general overview of the program, this communication deals with the steady-state run tests. It describes the way the experimental results are analysed, by means of two computer codes, and presents in details the main results and insight obtained from the statistical and spectral analysis