Fracturing of simulated high-level waste glass in canisters
Waste-glass castings generated from engineering-scale developmental processes at the Pacific Northwest Laboratory are generally found to have significant levels of cracks. The causes and extent of fracturing in full-scale canisters of waste glass as a result of cooling and accidental impact are discussed. 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. Overall, the study shows that the extent of glass cracking in full-scale, passively-cooled, continuous melting-produced canisters is strongly dependent on the cooling rate. This observation agrees with results of previously reported Pacific Northwest Laboratory experiments on bench-scale annealed canisters. Thus, the cause of cracking is principally bulk thermal stresses. Fracture damage resulting from shearing at the glass/metal interface also contributes to cracking, more so in stainless steel canisters than in carbon steel canisters. This effect can be reduced or eliminated with a graphite coating applied to the inside of the canister. 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 small amount of additional facility space is needed to accomodate slow-cooling canisters. Alternatively, faster cooling can be achieved using the multi-staged approach. Additional development is needed before this approach can be used on full-scale (60-cm) canisters.
- Research Organization:
- Battelle Pacific Northwest Labs., Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6052919
- Report Number(s):
- PNL-3948; ON: DE81030621; TRN: 81-016484
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
CARBON STEELS
IMPACT SHOCK
THERMAL STRESSES
CONTAINERS
MATERIALS
GLASS
RADIOACTIVE WASTE PROCESSING
SOLIDIFICATION
STAINLESS STEELS
FRACTURES
HIGH-LEVEL RADIOACTIVE WASTES
SIMULATION
SOLID WASTES
VITRIFICATION
ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
FAILURES
IRON ALLOYS
IRON BASE ALLOYS
MANAGEMENT
PHASE TRANSFORMATIONS
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
STEELS
STRESSES
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
052001* - Nuclear Fuels- Waste Processing
360603 - Materials- Properties
360103 - Metals & Alloys- Mechanical Properties