Waste Forms Technology and Performance Final Report (2011) / Chapter Skim
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5 Waste Form Testing
5 Waste Form Testing
Pages 119-152
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From page 119... ...
Release rates reflect the durability of a waste form material, that is, its resistance to physical and chemical alteration. A large number of standard test protocols have been established by the American Society for Testing and Materials (ASTM)
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From page 120... ...
. 5.1 PURPOSE OF WASTE FORM TESTING Laboratory testing of waste form materials is undertaken for several purposes, including to: • Conduct experiments to elucidate the release mechanisms of radio active and chemical constituents from a waste form material.
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its performance, and also to identify the ranges of processing variables that produce acceptable waste forms. The primary role of production control testing is to verify that the properties of a specific waste form product are consistent with the waste
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The testing of a waste form material in the laboratory can be related to acceptable performance of that material in a disposal facility by the following linking relationships (Ebert 2008; Plodinec and Ramsey, 1994) :3 process control ↔ composition control ↔ release rate control4 ↔ performance control ↔ acceptable performance (5.1)
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this linking relationship was established in a stepwise fashion: • Develop an acceptable waste form durability specification based on HLW performance modeling. As discussed in Chapter 8, acceptable fractional release rates for waste forms in a generic geologic reposi tory were determined to be between 10–4 to 10–6 parts per year5 (Crandall, 1983)
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From page 124... ...
In this case, each phase undergoes congruent dissolution, but technetium-99 and sodium will not be released into solution at the same rate. This approach was the basis for qualifying HLW glass from West Valley and the Savannah River Site in the Yucca Mountain Total System Performance Assessment–License Application (TSPA-LA)
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. Similarly, one cannot apply standard tests for borosilicate glasses to non-borosilicate glasses, because it is not known whether constituents in the latter material release congruently (Box 5.2)
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126 WASTE FORMS TECHNOLOGY AND PERFORMANCE TABLE 5.1 Summary of Waste Form Durability Response and Tests Waste Form Class Retention Mechanism Single-Phase Glasses Chemical incorporation Constituentsb are atomically bonded in the glass structure, usually to oxygen that is also bonded to other matrix elements (e.g., Si, Al, B, P) by short-range order (SRO)
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127 WASTE FORM TESTING Durability Appropriate Durability Test/ Standardsa Graphical Representation Behavior single phase ASTM C1220 EA, ARG-1, source – ASTM C1285 LRM, work for homogeneous ASTM C1662 borosilicate-based glass ASTM C1663 GCMs; testing and PUF standards must be developed for non-borosilicates single phase ASTM C1220 EA, ARG-1, Table 5.1-SinglePhaseGlasses.eps source -- ASTM C1285 LRM, work for homogeneous ASTM C1662 borosilicate based glass as long as ASTM C1663 GCMs; testing and crystalline phases PUF standards must do not sequester be developed for constituents non-borosilicates multiphase ASTM C1220 EA, ARG-1, Table 5.1-GlassCeramicMaterial.eps source -- glass ASTM C1285 LRM, work for and multiple ASTM C1662 borosilicate-based crystalline ASTM C1663 GCMs; testing and phases and grain PUF standards must boundaries be developed for non-borosilicates multiphase ASTM C1220 Testing and Table 5.1-GlassCeramicMaterial2.eps source -- single ASTM C1285 standards must be crystalline ASTM C1662 developed phase and grain ASTM C1663 boundaries PUF continued Table 5.1-SinglePhaseOxides.eps
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Multiphase Granular Oxides/Minerals/Metals Chemical incorporation and encapsulation Granular waste forms must be monolithed for disposal if not containerized. The monolithing agent does not incorporate constituents (gray shading)
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From page 129... ...
129 WASTE FORM TESTING Durability Appropriate Durability Test/ Standardsa Graphical Representation Behavior multiphase ASTM C1220 Testing and source -- multiple ASTM C1285 standards must be crystalline ASTM C1662 developed phases and grain ASTM C1663 boundaries PUF multiphase ASTM C1220 Testing and Table 5.1-MultiphaseOxides.eps source -- multiple ASTM C1285 standards must be crystalline phases ASTM C1662 developed but binder and ASTM C1663 grain boundaries PUF contain no constituents ASTM C1308 or ANSI 16.1 or EPA 1315 multiphase ASTM C1308 Radionuclides able 5.1-MultiphasegranulatedOxides.eps source -- multiple or or simulants must crystalline phases ANSI 16.1 or be measured or a but phases EPA 1315 standard developed encapsulate the constituents which exist primarily on the grain boundaries Table 5.1-CementationHydroceramics.eps
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. These kinetic effects may not be the same for phosphate glasses or phosphate mineral waste forms, and surface-layer effects may also be different in these materials.
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• C1662: Standard Practice for Measurement of the Glass Dissolu tion Rate Using the Single-Pass Flow-Through Test Method • C1663: Standard Test Method for Measuring Waste Glass or Glass Ceramic Durability by Vapor Hydration Test • C1220: Standard Test Method for Static Leaching of Monolithic Waste Forms for Disposal of Radioactive Waste • C1308: Standard Test Method for Accelerated Leach Test for Dif fusive Releases from Solidified Waste and a Computer Program to Model Diffusive, Fractional Leaching from Cylindrical Waste Forms Additionally, three other standard tests also used for waste form testing: • PNNL Pressurized Unsaturated Flow (PUF) Test • ANSI 16.1: Measurement of the Leachability of Solidified Low Level Radioactive Wastes by a Short-Term Test Procedure • EPA 1315: Mass Transfer Rates of Constituents in Monolithic or Compacted Granular Materials Using a Semi-Dynamic Tank Leaching Test Several new ASTM test protocols are also under development; for example, a version of C1662 is being developed for spent nuclear fuel (SNF)
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The waste form materials include, but are not limited to, glass, glass-ceramic, crystalline ceramics, oxides, and metallic waste forms. ASTM C1174 lays out a roadmap (Figure 5.1)
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Yes Adopt Model for License Application FIGURE 5.1 Logic roadmap to qualification of a waste form in a licensed geologic repository in the United States. Figure 5.1.eps SOURCE: From ASTM C1174-07.
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ASTM C1174 identifies what type of information is needed from various test methods and how that information should be applied. For most waste forms, it is expected that several test methods will be needed to understand the degradation mechanism(s)
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has been established to qualify new waste form materials for use in disposal applications. However, the use of this protocol to qualify a waste form material for which the release mechanism is not known and existing standard tests have not been demonstrated to be appropriate is a detailed and laborious process.
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From page 136... ...
MCC-1 and MCC-2 have become ASTM C1220 (Standard Test Method for Static Leaching of Monolithic Waste Forms for Disposal of Radioactive Waste) , MCC-3 has become ASTM C1285 (Standard Test Methods for Determining Chemical Durability of Nuclear, Hazardous, and Mixed Waste Glasses and Multiphase Glass Ceramics: The Product Consistency Test
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, and MCC-5 is the Soxhlet durability test often performed in Europe to evaluate waste form durability. Additionally, the International Atomic Energy Agency has recommended for durability testing the International Standards Organization standard ISO 6961 (Long-Term Leach Testing of Solidified Radioactive Waste Forms)
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Aug. 1984 DWPF construction began 1986 First waste compliance plan completed 1987-1994 Established reproducible glass performance test protocol (product consistency test)
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, or longer-term tests up to several years can be conducted. This test method can be used to compare the dissolution behaviors of candidate radioactive waste forms and to study their reactions during static exposure to dilute solutions in which solution feedback effects are small.
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PCT-A can specifically be used to obtain data to evaluate whether the chemical durability of glass waste forms has been consistently controlled during production via the linking relationships discussed in Section 5.1 of this chapter. In the case of homogeneous borosilicate HLW glasses, acceptable performance is defined as an acceptably low dissolution rate, which is controlled by maintaining the glass composition within an acceptable range.
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.3 PCT-B tests can be used to determine radionuclide solubilities in various groundwaters; as an accelerated test to determine long-term dissolution rates of waste form materials; and to determine when solubility-limited concentrations for some radioelements are reached. The measurement of such concentrations provides crucial inputs to performance assessment of disposal systems.
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Test Method, is used for the measurement of glass dissolution rates. This test is most frequently used on homogeneous glasses, including nuclear waste glasses, in various test solutions at temperatures less than 100°C.
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. Data interpretation is more complex with multiphase mineral waste forms because there are different source terms coming from the different mineral phases, unless comparisons can be made to the dissolution of single-phase natural analogue minerals and/or single-phase pure standards that have been tested for comparison.
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From page 144... ...
The VHT can be used to study the corrosion of glass and glass ceramic waste forms under conditions of high temperature and contact by water vapor or thin films of water. This method may serve as an accelerated test for some materials, because the high temperatures will accelerate thermally activated processes.
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. The VHT can be used as a screening test to determine the propensity of waste forms to alter and for relative comparisons in alteration rates between waste forms.
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It is applicable to any matrix material that does not degrade or deform during the test, including cements and other monolithic waste forms. It is a semi-dynamic test in which a monolithic specimen of prescribed dimensions is immersed in a large volume of leachant in a sealed vessel for a relatively short interval.
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bitmap SOURCE: EPA, 2009. procedure is used to measure and index the release of radionuclides from waste forms as a result of dissolution in demineralized water for five days or longer.
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leaching intervals are modified to improve quality control, (2) sample preparation accounts for mass transfer from compacted granular samples, and (3)
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1982. "Overview of Hydrothermal Testing of Waste Package Barrier Materials at the Basalt Waste Isolation Project," In Material Characterization Center Workshop on the Leaching Mechanisms of Nuclear Waste Forms, May 19-21, 1982, PNL-4382/ UC-70, Pacific Northwest Laboratory, Richland, Wash.
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Mineral Waste Forms: Characterization and Durability Testing," In Scientific Basis for Nuclear Waste Management XXX, D
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1981. Interim Performance Specifications for Waste Forms for Geologic Isolation, NWTS-19 DRAFT, Office of Nuclear Waste Isola tion, Columbus, Ohio (October)
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2000. Technical Progress Report on Single Pass Flow Through Tests of Ceramic Waste Forms for Plutonium Immobilization, UCRL ID-143361, Rev.
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