The work to determine the feasibility of using a quickoperating closure for the pressure vessel of the controlled Recirculation Boiling Reactor is described. An outline of the worb performed and the conclusions made is given. Datailed results of the self-energizing seal-evaluation tests are given. (W.D.M.)

A zirconium crystal bar, weighing 29 pounds and 1 5/16 inches in diameter by 8 feet in over-all length, was prepared, using pear-shaped zirconium couples to join the filament to the electrodes. This crystal bar was the largest produced to date in the 16-in.-diam. de Boer unit. The design of the couplings was modified to incorporate improvements indicated by the initial run, and another run is in progress. Binary alloys of Zr and Ni, Cr, and Si, as well as a zirconium alloy containing Fe, Al, and Si, were prepared for use as feed material in the small pyrex de Boer bulbs. The transfer of these elements from the feed to the crystal bar is being investigated. The rate of deposition and the type of crystal structure obtained with additions of various amounts of iodine are being studied. (auth)

From introduction: "This is the ninth monthly report, BMI-514, under Contract No. AT(30-1)-771 on "Zirconium Research and Development". The report covers the work period from September 15, 1950, to October 15, 1950. Work is continuing on the preparation of large-diameter zirconium crystal bars in the 16-inch-diameter de Boer unit. Crystal bars up to 1-5/16 inches in diameter and 8 feet long have been prepared in this unit."