Waste-glass castings generated from engineering-scale developmental processes at the Pacific Northwest Laboratory are generally found to have significant levels of cracks. This report discusses the causes and extent of fracturing in full-scale canisters of waste glass as a result of cooling and accidental impact. The work was performed at the Pacific Northwest Laboratory under the High-Level Waste Container Development Project, part of the U.S. Department of Energy's Long-Term High-Level Waste Technology Program technically coordinated by Savannah River Laboratory. Although the effects of cracking on waste-form performance in a repository are not well understood, cracks in waste forms can potentially increase leaching surface area. If cracks are minimized or absent in the waste-glass canisters, the potential for radionuclide release from the canister package can be reduced. Additional work on the effects of cracks on leaching of glass is needed. In addition to investigating the extent of fracturing of glass in waste-glass canisters, methods to reduce cracking by controlling cooling conditions were explored. Thermal fracturing can be controlled by using a fixed amount of insulation for filling and cooling of canisters. In order to maintain production rates, a vi small amount of additional facility space is needed to accomodate slow-cooling canisters. Alternatively, faster cooling can be achieved using the multistaged approach. Additional development is needed before this approach can be used on full-scale (50-em) canisters. vii. .