TRITIUM AND HELIUM RELEASE FROM IRRADIATED BERYLLIUM

Tritium and helium release behavior have been measured for Be specimen s irradiated at 75 degrees C in the Advanced Test Reactor (ATR) to a f ast neutron fluence of 5x10(22) n/cm(2). Stepped-isothermal anneal exp eriments were conducted from room temperature to above the melting poi nt of Be, with the temperature steps varied from one experiment to the other. In-line ion chambers and quadrupole mass spectrometers were us ed to measure the gases released to an Ar process gas stream flowing a cross a heated specimen. Gases released from the specimens included H- 2, He-3, He-4, and tritium as HT and T-2. Release of the hydrogenic an d tritium gases were observed to be concurrent with the release of hel ium, providing direct evidence of these gases in microscopic helium bu bbles in the irradiated Be. Tritium and helium release kinetics were d ependent on the magnitude of the temperature steps between 600 degrees C and 800 degrees C.