The Impact of the Proposed delta Gp Limits on Glass Formulation Efforts: Part II. Experimental Results

PEELER, DAVID

Savannah River Site (S.C.)

关键词: Sludges;    Global Positioning System;    Wastes Durability;    Waste Processing;    Hydroxides;   

DOI  :  10.2172/835580
RP-ID  :  WSRC-TR-2004-00348
RP-ID  :  AC09-96SR18500
RP-ID  :  835580

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Savannah River National Laboratory (SRNL) has initiated studies to assess alternative durability options that may provide access to compositional regions of interest in support of the accelerated cleanup mission at the Defense Waste Processing Facility (DWPF). One of the options being pursued is the redefinition of the durability model acceptability limits. Some of the conservative steps used in establishing the current limits without compromising the high confidence required for meeting the specification on the waste form quality were identified and eliminated. The results led to a set of three new Property Acceptability Region (PAR) values for the preliminary glass dissolution estimator that has the potential to allow access to compositional regions of interest to improve melt rate or waste loading. Although these limits are available for implementation, there is no driving force to do so with the current sludge batch (i.e., the current Frit 418 - Sludge Batch 3 (SB3) system is TL limited). The objectives of this task were to investigate (and generate) the incentive of applying the proposed durability limits in the Product Composition Control System (PCCS) from a glass formulation perspective. Glass compositions were identified or developed to transition into and through the region of GP acceptability as defined by the current and proposed durability limits. The progression through the newly defined acceptability region was accomplished by increasing the total alkali in the glass via higher alkali frits and/or waste loading (WL). The focus of this report is on the measured durability response as it compares to model predictions to assess the applicability and/or potential conservatism of the various limits or durability approaches. The normalized boron release values (NL [B] g/L) for the study glasses ranged from approximately 1.0 g/L to 2.0 g/L. The Product Consistency Test (PCT) responses provide evidence that implementation of the proposed GP limits will provide access to higher alkali compositional regions without compromising product quality. In fact, the data provide evidence that the proposed limits may still be overly conservative. These results also provide continued incentive to assess the index system and other durability alternatives to provide access into compositional regions of interest to improve melt rate and waste loading which play a major role in defining waste throughput for DWPF. Although incentive for implementation of the proposed durability limits (for the pursuit of alternative durability approaches) has been demonstrated through this study in terms of the measured durability response for higher alkali systems, assessments of melt rate should be performed to establish a clear motive or driver for implementation. More specifically, a ''significant'' increase in melt rate may be required to provide the incentive for DWPF to implement the change rather than a ''paper study'' incentive or PCT assessment.