. "Immobilization of High Level Waste: Analysis of Appropriate Synthetic Waste Forms." An International Spent Nuclear Fuel Storage Facility -- Exploring a Russian Site as a Prototype: Proceedings of an International Workshop. Washington, DC: The National Academies Press, 2005.
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An International Spent Nuclear Fuel Storage Facility: Exploring a Russian Site as a Prototype - Proceedings of an International Workshop
TABLE 1 Basic Radioisotopes in High-Level Wastes from the Reprocessing of Spent Nuclear Fuel and Their Half-Lives
Basic Fission Products and Corrosion Elements (β- and γ-emitters)
Transuranic Actinides (α-emitters)
Radionuclide
T1/2, in years
Radionuclide
T1/2, in years
90Sr
29
237Np
2.1 × 106
93Zr
1.5 × 106
238Pu
89.9
99Tc
2.1 × 105
239Pu
2.4 × 104
126Sn
105
240Pu
6.5 ×103
129I
1.7 × 107
241Pu
14
137Cs
30
242Pu
3.78 × 105
147Pm
2.6
241Am
433
151Sm
93
242Am
152
154Eu
16
243Am
7.3 × 103
Activated corrosion products
243Cm
28
59Ni
7.5 × 104
244Cm
17.9
60Co
5.3
245Cm
8.5 × 103
63Ni
96
246Cm
4.76 × 103
with the study of various vitreous and crystalline materials based on silicates, phosphates, and titanates.3 For industrial-scale operations for this purpose, glasses are currently used—borosilicate glasses abroad4 and aluminophosphate glasses in Russia.5 The shortcoming of glasses is their limited capacity to incorporate actinides (especially plutonium) and their low chemical stability.6 The interaction of glass-like matrices with underground water is accompanied by the formation of colloidal particles7 in which radionuclides could migrate over great distances. In addition, glasses crystallize over time, further reducing the stability of radionuclide fixation due to the appearance of soluble phases—silicates or phosphates of the alkali and alkaline earth metals, molybdates, and so forth.
To manage them more efficiently wastes may be separated into radionuclide fractions.8 In one of these fractions the actinide content totals tens of percent by mass, and there is a significant amount of zirconium and lanthanides. The ratio of quantities of these elements in liquid high-level wastes from the reprocessing of spent fuel from various reactors is characterized as follows: actinides 10–15 percent by mass; lanthanides 60–65 percent by mass; and zirconium 20–25 percent by mass.9 Predominant among the actinides are uranium, neptunium, plutonium, and americium, while the lanthanide group is represented by neodymium, cerium, lanthanum, and praseodymium. Another group of wastes with high actinide content is created during the conversion of metallic weapons-grade plutonium into nuclear fuel.10
Besides glass, crystalline matrices represent an alternative waste form with high actinide content.11 More than 20 phases with various capacities for the
