Summary: Heat transfer tests employing the two-rod test section without film tripping devices have been completed. Representations defining critical heat flux, transition boiling and film boiling behavior at high pressures and over a steam quality range of 25 to 90 percent are shown. Fabrication of a new observational test section was completed and initial test results with high-speed motion pictures were obtained. A test loop instability which was found to affect transition boiling behavior was detected and partially eliminated.

The United States and the European Atomic Energy Community (Euratom), on May 29, and June 18, 1958, signed an agreement which provides a basis for co-operation in programs for the advancement of the peaceful applications of atomic energy. The work described in this report represents the Joint U.S.-Euratom effort. The over-all development program is designed to obtain the test data and operating experience necessary to eventually realize a 50 percent increase in the output of the Garigliano Nuclear Power Station located at Sessa Aurunca (Campania, Italy). Two tasks are in progress: Task III-F involves the preparation of test specimens of reactor vessel material for irradiation; Task IV consists of the formulation of specification for a complete data logging and computer system.

Development of nuclear reactor cores having high power density, long fuel life, and low fabrication costs is the objective of this program sponsored by the AEC. Five tasks are in progress: (1) Task 1A-High Power Density Fuel Development. All fuel irradiation has been terminated with the final shutdown of the VBWR. The high burnup average achieved by a single assembly in the group is 10,000 MWD/T (assembly 1F). Twenty-one of the original 24 assemblies have failed or are suspected of failure. Profilometer tests rung on HPD assembly 2E, Rod B, indicate that localized clad deformation occurs during operation. (2) Task 1B-Fuel Fabrication Development. Assembly. All fuel irradiation has been terminated with the final shutdown of the VBWR. The highest average burnup achieved by a single assembly in the group was assembly 4S with 8400 MWD/T. All assemblies in the group have failed or are suspected of failure. The Phase I developmental fuel continues to be irradiated in the Big rock Point reactor with the lead assembly having reached 1500 MWD/T. Fifteen phase II developmental assemblies are being construction for insertion at Big Rock Point in March. Engineering is underway to provide one instrumented assembly probe and two spare flowmeters for …