As part of international agreement between the United States and Russia, a significant amount of plutonium requires disposition. One of the disposition paths is to immobilize it and dispose of it in a geological repository. The two favored immobilization forms are glass and ceramic. The plutonium, as an oxide, would be reacted with the glass or ceramic to form a homogeneousmaterial. The resulting solid product would then be encased in High-Level Waste (1-ILW)glass for the can-in-canister option. The HLW glass gives a radiation barrier to increase proliferation resistance. The glass canister would then be disposed of by geological emplacement. This paper discusses how glass meets two criteria: the condition of significant actinide volubility, and That the PuO{sub 2} feed should be incorporated into the matrix without significant amount of unreacted material.

Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 280 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.

We have started a search for High Redshift Radio Galaxies (HZRGS) in an area covering 7 sr by selecting a sample of Ultra Steep Spectrum (USS) sources with a low flux density cut-off S1400 > 10 mJy and a steep spectral index cut-off of a < -1.3 (S of about nu-alpha) from the WENSS, NVSS and TEXAS surveys. Our first results for 27 sources show that we are almost twice as effective in finding HZRGs than than surveys of relatively bright radio sources with a spectral index cut-off of a < - 1.0. The redshift distribution is consistent with an extension of the z - a relation to a < -1.3, but a large fraction of our sample (40%) consists of objects which are too faint to observe with 3-4 m class telescopes. Our search is aimed at increasing the number of very high redshift radio galaxies for further detailed studies of the formation and evolution of massive galaxies and their environment.