Vitrification and Testing of Hanford Pretreated Low Activity Waste

Actual pretreated LAW samples were vitrified to demonstrate the RPP-WTP projects ability to satisfy the LAW product ORP Phase B-1 contract requirements concerning, chemical and radionuclide reporting, waste loading, identification and quantification of crystalline and non-crystalline phases, and waste form leachability. Chemical compositions of two LAW glasses (i.e. elements (excluding oxygen) present in concentrations greater than 0.5 percent by weight) were measured using KOH and Na2O2 fusion preparation procedures. The measured wt% sodium oxide content for the AW-101 and AN-107 glasses are 17.7 and 18.3 respectively; however, it is argued herein that process knowledge, i.e. the target sodium oxide content, is better than the analytical measurement. Therefore for both LAW glasses the target oxide loading for sodium of 20 wt% is accepted. At these levels the glass meets or exceeds both the RPP-WTP glass specification and the DOE ORG contract requirement for waste sodium loading. The concentrations of 137Cs, 90Sr, 99Tc and transuranic (TRU) radionuclides for AW-101 and AN-107 are: (1) 0.231 and 0.292 Ci/m3, 0.435 and 0.005 Ci/m3, 0.019 and 0.129 Ci/m3, andlt; 0.16 andlt; 2.6 nCi/g, respectively. The ORP contract criteria for 137Cs, 90Sr and TRU (shall be less than 3 Ci/m3, 20 Ci/m3, and 100 nCi/g, respectively) are met in both glasses. The ORP contract criteria for 99Tc (shall be less than 0.1 Ci/m3) is met explicitly by AW-101 and will be met for the AN-107 glass by averaging its 99Tc content over the previous LAW glasses produced to meet the contract. After canister centerline cooling, no crystals were observed in the AW-101 and AN-107 glasses by XRD, optical examination and SEM analysis. The normalized PCT release rates of sodium, silicon, and boron at both 40 and 90 C from the AW-101 and AN-107 glasses are less than 2.0 g/m2 the ORP contract criteria