Liquid film emergency for FRJ-2 type research reactors

A new, efficient emergency cooling procedure based on liquid film cooling was developed for FRJ-2 type research in reactors, which allows a higher power generation in the tubular fuel elements used and which represents an improvement of the engineered safeguards of the reactor. The problem of producing coherent liquid films on the outer surfaces of the four concentrically arranged thin fuel tubes without obstructive modifications of the fuel element design was solved by using radial water jets. These jets discharge into the drained fuel elements from the outside therby crossing the upper edges of the fuel tubes. In hydraulic experiments the influence of the geometry, of the jet velocity and of the water viscosity on the water supply to each fuel tube was measured and the conditions were evaluated where by each fuel tube in the reactor obtain sufficient cooling water taking account of variations in the various parameters. (orig./HP)