Technical support is important for all U.S. Department of Energy (DOE) facilities facing difficult technical issues, aggressive remediation schedules, and tight budgets. It is especially vital for closure sites, which typically are smaller and have fewer resources available to apply to remediation activities. In many cases, closure sites and other small sites no longer have staff with the expertise required to overcome technical barriers on their own. As closure deadlines approach, special technical expertise is needed to identify, evaluate, and implement new and innovative approaches that will result in significant cost and schedule improvement for the waste disposition pathway. Site ''problem holders'' must have access to world-class scientific and engineering expertise from DOE national laboratories and research facilities, private industry, and universities to address immediate critical problems. In order to have confidence in the feasibility and results of innovative approaches, site contractors need to have the benefit of the valuable experiences of technicians who have faced similar problems and found solutions. The DOE Environmental Management (EM) Science and Technology (S&T) program recognizes the need of the closure sites to solve problems aggressively and is highly responsive to this need. Technical support from the S&T program can take many forms, such …

We have studied the spin relaxation in diluted spin ice Ho{sub 2-x} Y{sub x} Ti{sub 2}O{sub 7} by means of neutron spin echo spectroscopy. Remarkably, the geometrical frustration is not relieved by doping with non-magnetic Y, and the dynamics of the freezing is unaltered in the spin echo time window up to x {approx_equal} 1.6. At higher doping with non-magnetic Y (x {ge} 1.6) a new relaxation process at relatively high temperature (up to at least T {approx_equal} 55 K) appears which is more than 10 times faster than the thermally activated main relaxation process. We find evidence that over the whole range of composition all Ho spins participate in the dynamics. These results are compared to a.c. susceptibility measurements of the diluted Ho and Dy spin ice systems. X-ray absorption fine structure (EXAFS) spectra and x-ray diffraction show that the samples are structurally well ordered.