Heat transfer crisis investigation on 19-rod cluster with high peaking factor of power density

Experimental data on the heat transfer crisis in a 19-tubes bundle with the radial power density nonuniformity coefficient of 1.828 are presented. The tubes with 9 mm outer diameter were arranged in staggered order with 12.2 mm pitch. The bundle heated length was 2.5 m. The averaged values of the calculated/experimental critical heat flux density ratio for unidimensional approximation were found to be 1.545, 1.067 and 0.87 in case of the optimistic estimate, the mean estimate for an imaginary 'hot' bundle and the mean estimate for a 'hot' subchannel respectively. These results have been obtained when calculating the critical thermal loads with the use of the steam consent in the critical cross-section. When calculating was based on the experimental values of the coolant inlet subcooling those ratios were 1.340, 1.035 and 0.94 respectively. The obtained calculation data has shown both unidimensional mean estimates to provide satisfactory results. The critical heat flux density calculations were performed on VEVERKA code. The average calculated/experimental critical heat flux density ratio was found to be 0.9