FAST FLUX TEST FACILITY DEVELOPMENT MONTHLY PROGRESS REPORT

Measurements of the reaction of methane with sodium have been extended to 1400°F, where 100 ppm in helium completely reacted in 3-1/2 hours. It was also determined that the volume of sodium in the system has little effect on the reaction rate, An important milestone was achieved in the development of electrical heaters for simulation of fuel pins for use in future heat transfer studies on FFTF fuel assembly models. In a demonstration test, a tantalum coaxial heater was operated continuously for six hours at a heat flux of 1,000,000 Btu/hr-ft{sup 2} in water at 320°F outlet temperature, The heater then operated at 1,300,000 Btu/hr-ft{sup 2} for an additional 4-1/2 hours before the test was terminated due to electrode failure. The fabrication of the test facility required to demonstrate and establish the feasibility of gas cooling of FFTF fuel elements during inspection and disassembly was completed. A preliminary study was made to determine the feasibility of utilizing facilities such as the Hydraulic Core Mockup, the Seven-Duct Mockup, tile Reactor Cover Mockup, and the Sodium Facilities Building for Fuel Handling Machine and Radioactive Maintenance equipment interface testing. With modification, each or all of the above facilities could be applied in the program. Final PNL recommendations will be made in February. Based on a summary of stainless steel volume expansion data at exposures to 8 x 10{sup 22} nvt, it appears that as mucn as 10% volume increase may occur at 10{sup 23} nvt and irradiation temperatures of 800°F to 1100°F. A preliminary assessment, from computer simulations, of radiation damage processes yields the following ranking in relative damaging power for void production in fuel cladding: EBR-II > DFR > FTR. This ranking is based on the number of primary knock-on atoms (PKA) with energy greater than 3 keV produced per interaction with neutrons. All neutrons with energy greater than 25 eV were considered, Results also showed no significant difference in PKA production between samples the size of tensile specimens and samples the thickness of FTR fuel clad