Preliminary results from experiments on the dissolution of beryllium metal and sintered UO2-BeO fuel pellets are reported. In all cases the pellets were fired in hydrogen at 1650-1800°C. Uranium, from UO2-BeO pellets containing more than 60% UO2, is readily leached with boiling 6-13 M HNO3 in about 6 hr. The BeO in these pellets dissolves only slowly in nitric acid; however, in 8 M HNO3-0.2M NaF, it dissolves at about the same rate as the UO2. Sintered pellets containing less than 10% UO2 do not dissolve rapidly in common aqueous reagents. The highest rates are obtained in boiling acidic fluoride solutions; e.g., sintered BeO and BeO-8% UO2 are dissolved initially at a rate of about 1.7 mg min-1cm-2 (13 mils/hr) in boiling 5.8 M NH4HF2.

The absorption in lead of Bremsstrahlung X radiation from a Sr^90 TiO3 pellet in the proximity of Hastelloy "C" was measured. The tenth value layer of the more energetic components of the X-ray continuum was determined to be 1.60 inches.

From Introduction: "The present semiannual progress report introduces more active consideration than has been given in the past (by us, at least) to the importance of energy degradation in DCX-like devices. The following pages introduce also a new major apparatus designated as DCX-2. Some of these concepts cannot as yet be released publicly and therefore Chap. 3 of this report, covering the DCX-EP-B design, is being issued separately, with restricted distribution, as ORNL-3044."