Round robin CHF testing of an ITER vertical target swirl tube

A series of international CHF experiments was undertaken on a swirl tube supplied by CEA at laboratories from three different Home Teams in the ITER program. Global CHF testing was conducted at FE-200 in France, the EB-1200 in the US and PBEF in Japan. The swirl tube, envisioned for use in the ITER vertical target, was tested at each facility using ITER cooling conditions of 100°C: local subcooling and 12 m/s water. Both flat and peaked heat flux profiles were used on 100 mm and 200 mm heated lengths, respectively. Good performance of the swirl tube was validated in all three facilities. Burnout or global CHF values of 27 MW/m² were attained for the flat nominal profile and 30 to 37 MW/m² peak heat fluxes were determined for the highly peaked ITER transient profile. A comparison of test results and CHF detection techniques between the three facilities is presented. Peaking factors were determined by finite element analysis as were predictions of uniform heating and the peak heat flux for transient profile heating