DESIGN MODIFICATIONS TO THE SRE DURING FY 1960

The means used to prevent the recurrence of tetralin leakage into the SRE sodium systems are discussed. Included is a description of the redssign of system components to utilize alteraate coolants such as nitrogen, air, and NaK. The use of kerosene to replace tetralin, where double containment is provided, is discussed. The physical properties are compared, and kerosene is shown to be free of the undesirable characteristics of tetralin. The fuelelement cleaning systsm was redesigned for steam washing, followed by a water rinse and vacuum drying. Hydrogen gas evolved during washing is oxidized with copper oxide to eliminate the possibility of a hydrogen-oxygen explosion if air should accidentally enter the vent system. The fuel element was changed from a seven- to a five-rod cluster to provide additional clearance in the channel. Element hardware was modified to provide an orifice location which will permit more precise flow calculations; a redesigned hanger assembly which will minimize sodium holdup; and filter screene at the channel entrance to prevent in-cluster plugging. Diagnostic instrumentation was provided for the reactor to monitor: fission-product activity in the reactor cover gas; rapidly varying reactor parameters during a reactor scram; internnl and aheath fuel temperatures; and fuinctions being performed whioh wiIl indicate the mode of operation. The data wiIl provide additionul information to the reactor operator, as well as provide a more comprehereive coverage for reaotor analysis. (auth