The author wishes to express his thanks to the personnel of the Fluids Laboratory Division for their efforts in conducting the tests and gathering the data, to the personnel of the' 'l'est integration and Coordination Scction for vcr~f~cation and documcntiltion of the data, to R. F. Farman and R. W. Shumway for technical support, to D. M. Snider for supplying core heat transfer calculations, to G. W. Johnsen and J. K. Meier for supplying E L A P 4 calculations, to K. A. Dietz for editing and iillprovillg the quality of the overall report, and to L. A. Nelson and L. K. Keller for typing the various drafts.