Summary: The High Power Density Project includes a comprehensive fuel development program which has the objective of developing and demonstrating the performance of a nuclear reactor core having a high power density, long fuel life, and low fabrication cost. The fuel program is made up of two principal tasks. Task 1A consists of irradiation tests in the VBWR of Type 304 stainless steel clad, UO2 pellet type fuel rods fabricated by current commercial processes. Task 1B consists of the investigation of lower cost fabrication processes and the irradiation testing of fuel elements fabricated by these processes. Both tasks include the investigation of the feasibility and use of thin-wall stainless steel cladding as a means of improving the neutron economy and fuel cycle costs of stainless steel clad fuel. Irradiation of the Task 1A fuel assemblies in the VBWR was initiated in September, 1960. Subsequently, Task 1B fuel assemblies were inserted in the VBWR as various fabrication processes and design concepts were investigated. Fuel cladding failures have occurred in fuel rods in both Task 1A and 1B. As of this date, cladding failures have occurred in twenty-two rods of approximately 700 fuel rods which have been irradiated. Twenty of the failures …

Abstract: Neutron flux and gamma radiation measurements through the SM-1 primary shield were made at the startup of Core II in June 1961. They extend previous measurements (APAE-35) both vertically and horizontally in the primary shield and in the rod drive pit. Dose rate measurements on spent fuel elements under water are also reported.