Experimental studies of PWR safety injection branch flow

The safety injection water, injected through the auxilliary piping in the primary circuit of pressurized water reactors, may be at a temperature significantly different from that of the primary fluid. Some fatigue analyses have shown that it is necessary to install thermal sleeves for protecting nozzles against cyclical thermal stresses. Moreover, the primary flow can induce vibrations at a level which can have a detrimental effect on the thermal sleeve. This paper shows the results of an experimental study performed by Framatome, which presents both the thermal efficiency and the vibration behaviour of thermal sleeves. Two reduced scale models (1/5) of a 12 inch size nozzle have been tested. One nozzle is perpendicular to the main circuit, the other inclined at 450. (Auth.)