scholarly journals Advanced Experimental Technique for Radiation Damage Effects in Nuclear Waste Forms: Neutron Total Scattering Analysis

MRS Advances ◽  
2018 ◽  
Vol 3 (31) ◽  
pp. 1735-1747
Author(s):  
Maik Lang ◽  
Eric C. O’Quinn ◽  
Jacob Shamblin ◽  
Jörg Neuefeind
Keyword(s):  
Long Range ◽  
Radiation Effects ◽  
Fission Products ◽  
Waste Form ◽  
Waste Forms ◽  
Wide Range ◽  
Pdf Analysis ◽  
Defect Behavior ◽  
Nuclear Waste Forms ◽  
Neutron Total Scattering

ABSTRACTFor the past 30 years, the development of durable materials for radionuclide immobilization has been driven by efforts to dispose of wastes generated by the nuclear fuel cycle [National Research Council, ‘Waste Forms Technology and Performance: Final Report’, the National Academies Press, Washington D.C., 2011]. Many materials have been developed, but there still exist large gaps in the knowledge of fundamental modes of waste form degradation in repository environments. An important aspect of waste form science is the behavior of the materials under intense irradiation from decaying actinides and fission products. This irradiation induces a wide range of defects and disorder, the details of which depend on the specific waste form material. At the present time, it is not fully explained how radiation effects will influence the performance of nuclear waste forms and their long-term retention of fission products and actinides under operational conditions. The complex defect behavior and radiation damage must be understood over a range of length scales, from the initial atomic-scale defect structure to the long-range observable material modification. This is particularly challenging and requires advanced characterization techniques. This contribution describes how pair distribution function (PDF) analysis obtained from neutron total scattering experiments can be applied in the research field of waste form science to uniquely characterize radiation effects in a wide range of materials, including crystalline complex oxides and waste glasses. Neutron scattering strength does not have an explicit Z-dependence; this allows access to many low-Z elements, such as oxygen, that cannot be accurately studied with X-rays. In many cases, this can permit a detailed analysis of both cation (often high-Z) and anion (often low-Z) defect behavior. In contrast to traditional crystallography, which relies on long-range order, PDF analysis probes the local defect structure, including changes in site occupation, coordination, and bond distance. This is particularly important when characterizing aperiodic waste glasses with no long-range order at all. In contrast to X-ray characterization which requires very little sample mass (∼0.1 mg), neutron characterization (even at state-of-the-art spallation facilities) requires relatively large sample mass (∼50 - 100 mg). Obtaining this quantity is challenging for studies of irradiated materials, but by tailoring our experimental approach to use high-energy ions (GeV) with very high penetration depth, we are able to produce the required mass.

Corrosion Testing of Stainless Steel-Zirconium:Metal Waste Forms

1999 ◽  
Vol 556 ◽  
Author(s):  
D. P. Abraham ◽  
L. J. Simpson ◽  
M. J. Devries ◽  
S. M. Mcdeavitt
Keyword(s):  
Stainless Steel ◽  
Spent Nuclear Fuel ◽  
Fission Products ◽  
Waste Form ◽  
Waste Forms ◽  
Immersion Corrosion ◽  
Corrosion Studies ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Nuclear Waste Forms

AbstractStainless steel-zirconium (SS-Zr) alloys have been developed as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The waste forms incorporate irradiated cladding hulls, components of the alloy fuel, noble metal fission products, and actinide elements. The baseline waste form is a stainless steel- 15 wt% zirconium (SS-15Zr) alloy. This article presents microstructures and some of the corrosion studies being conducted on the waste form alloys. Electrochemical corrosio n, immersion corrosion, and vapor hydration tests have been performed on various alloy compositions to evaluate corrosion behavior and resistance to selective leaching of simulated fission products. The SS-Zr waste forms immobilize and retain fission products very effectively and show potential for acceptance as high-level nuclear waste forms.

A Study of Radiation Effects in Curium-Doped Gd2Ti2O7 (Pyrochlore) and CaZrTi2O7 (Zirconolite)

1981 ◽  
Vol 11 ◽  
Author(s):  
J.W. Wald ◽  
P. Offemann
Keyword(s):  
Radiation Damage ◽  
Nuclear Waste ◽  
Radiation Effects ◽  
Laboratory Data ◽  
Primary Host ◽  
Waste Forms ◽  
Rare Earth Titanate ◽  
Effects Of Radiation ◽  
Similar Phase ◽  
Nuclear Waste Forms

Radiation effects studies in both glass and glass ceramic nuclear waste forms have identified a rare-earth titanate phase of the general formula (RE) 2Ti207 which is capable of acting as a host phase for actinides.1,2 Ringwood and co-workers3 have also proposed a structurally similar phase, zirconolite (CaZrTi2 07), as one of the primary host phases in the SYNROC waste form. Data from these and other previous studies, as well as mineralogical information available on these titanate phases, have not provided an unambiguous interpretation of the effects of radiation damage relative to nuclear waste forms. This paper reports new laboratory data concerning radiation damage effects in both of these phases.

TEM Analysis of Corrosion Products From a Radioactive Stainless Steel-based Alloy

2000 ◽  
Vol 6 (S2) ◽  
pp. 368-369
Author(s):  
N.L. Dietz ◽  
D.D Keiser
Keyword(s):  
Stainless Steel ◽  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Fission Products ◽  
Waste Form ◽  
Metallic Sodium ◽  
Geologic Repository ◽  
Tem Analysis ◽  
Waste Forms

Argonne National Laboratory has developed an electrometallurgical treatment process for metallic spent nuclear fuel from the Experimental Breeder Reactor-II. This process stabilizes metallic sodium and separates usable uranium from fission products and transuranic elements that are contained in the fuel. The fission products and other waste constituents are placed into two waste forms: a ceramic waste form that contains the transuranic elements and active fission products such as Cs, Sr, I and the rare earth elements, and a metal alloy waste form composed primarily of stainless steel (SS), from claddings hulls and reactor hardware, and ∼15 wt.% Zr (from the U-Zr and U-Pu-Zr alloy fuels). The metal waste form (MWF) also contains noble metal fission products (Tc, Nb, Ru, Rh, Te, Ag, Pd, Mo) and minor amounts of actinides. Both waste forms are intended for eventual disposal in a geologic repository.

Ion Implantation Studies of Nuclear Waste Forms

1981 ◽  
Vol 6 ◽  
Author(s):  
Clyde J. M. Northrup ◽  
George W. Arnold ◽  
Thomas J. Headley
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Alpha Decay ◽  
Lead Ions ◽  
Waste Form ◽  
Elastic Recoil ◽  
Elastic Recoil Detection ◽  
Waste Forms ◽  
Basic Studies ◽  
Nuclear Waste Forms

ABSTRACTThe first observations of physical and chemical changes induced by lead implantation damage and leaching are reported for two proposed U.S. nuclear waste forms (PNL 76–68 borosilicate glass and Sandia titanate ceramics) for commercial wastes. To simulate the effects of recoil nucleii due to alpha decay, the materials were implanted with lead ions at equivalent doses up to approximately 1 × 1019 a decays/cm3 . In the titanate waste form, the zirconolite, perovskite, hollandite, and rutile phases all exhibited a mottled appearance in the transmission electron microscope (TEM) typical of defect clusters in radiation damaged, crystalline solids. One titanate phase containing uranium was found by TEM to be amorphous after implantation at the highest dose. No enhanced leaching (deionized water, room temperature, 24 hours) of the irradiated titanate waste form, including the amorphous phase, was detected by TEM, but Rutherford backscattering (RBS) suggested a loss of cesium and calcium after 21 hours of leaching. The RBS spectra also indicated enhanced leaching from the PNL 76–68 borosilicate glass after implantation with lead ions, in general agreement with the observations of Dran, et al. [6,7] on other irradiated materials. Elastic recoil detection spectroscopy (ERD), used to profile hydrogen after leaching, showed penetration of the hydrogen to several thousand angstroms for both the implanted and unimplanted materials. These basic studies identified techniques to follow the changes that occur on implantation and leaching of complex amorphous and crystalline waste forms. These studies were not designed to produce comparisons between waste forms of gross leach rates.

Interpreting Uranyl Mineral Diffraction Patterns

1998 ◽  
Vol 4 (S2) ◽  
pp. 560-561
Author(s):  
Edgar C. Buck
Keyword(s):  
Corrosion Behavior ◽  
Nuclear Waste ◽  
Equatorial Plane ◽  
Waste Form ◽  
Spent Fuel ◽  
Secondary Phases ◽  
Form Complex ◽  
Waste Forms ◽  
Diffraction Patterns ◽  
Nuclear Waste Forms

Secondary phases that form during the corrosion of nuclear waste forms may influence both the rate of waste form dissolution and the release of radionuclides [1]. The identification of these phases is critical in developing models for the corrosion behavior of nuclear waste forms. In particular, the secondary uranyl (VI) minerals that form during waste form alteration may control uranium solubility and release of radionuclides incorporated into these phases [2].The U6+ cation in uranyl minerals is almost always present as a linear (UO2)2+ ion [3]. This uranyl (Ur) ion is coordinated by four, five, or six anions (ϕ) in the equatorial plane resulting in the formation of square (Urϕ4), pentagonal (Urϕ5), and hexagonal (Urϕ6) bipyramids, respectively [3]. These bipyramid polyhedra may polymerize to form complex infinite sheet structures. The linking of Urϕ5 is observed in a number of uranyl minerals formed during waste glass and spent fuel corrosion [2,4], such as weeksite [Na,K(UO2)2(Si205)3*4H2O] and β-uranophane [Ca[(UO2)(SiO3OH)]2*5H2O].

Progress at ANSTO on a Synroc Plant for Intermediate-Level Waste from Reactor Production of 99Mo

2014 ◽  
Vol 94 ◽  
pp. 111-114 ◽  
Author(s):  
Eric R. Vance ◽  
S.A. Moricca ◽  
M.W.A. Stewart
Keyword(s):  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Liquid Waste ◽  
Fission Products ◽  
Intermediate Level ◽  
Waste Form ◽  
Production Plant ◽  
Reducing Atmosphere ◽  
Nuclear Waste Forms ◽  
Reactor Production

Intermediate level waste from ANSTO’s expanded 99Mo production plant will consist of ~5000L/year of 6M NaOH + 1.4 NaAlO2 + fission products. Detailed engineering is being carried out on a synroc plant to immobilise this waste in a glass-ceramic, with completion scheduled for 2016. The liquid waste will be mixed with precursors and dried before being calcined in a reducing atmosphere to control fission product volatility. The calcine will be transferred to 30L metal cans which will be hot isostatically pressed at 1000°C/30MPa for 2h, then cooled to room temperature and stored preparatory to final disposal. Laboratory scale waste form material will pass 90°C PCT tests. In addition, legacy intermediate level uranyl nitrate-based liquid waste from 99Mo production at ANSTO between the 1980s and 2005 via irradiation of UO2 targets will also be immobilised by the same process to form a Synroc-type waste form. Some examples illustrating the wide applicability of hot isostatic pressing to consolidate nuclear waste forms will be given showing the advantages for particular wastes, notably high waste loadings and the absence of off-gas in the high temperature consolidation step. The immobilisation of a variety of low-level liquid and solid wastes from 99Mo production will also be discussed.

scholarly journals Radiation Effects Issues Related to U.S. Doe Site Remediation and Nuclear Waste Storage

1994 ◽  
Vol 353 ◽  
Author(s):  
William J. Weber ◽  
Rodney C. Ewing
Keyword(s):  
Nuclear Waste ◽  
Radiation Effects ◽  
Nuclear Waste Storage ◽  
Radiation Fields ◽  
Waste Storage ◽  
Waste Forms ◽  
Site Restoration ◽  
Physical And Chemical ◽  
The Impact ◽  
Nuclear Waste Forms

AbstractSite restoration activities at DOE facilities and the permanent disposal of nuclear waste generated at the same DOE facilities involve working with and within various types and levels of radiation fields. Radionuclide decay and the associated radiation fields lead to physical and chemical changes that can degrade or enhance material properties. This paper reviews the impact of radiation fields on site restoration activities and on the release rate of radionuclides to the biosphere from nuclear waste forms.

scholarly journals Radiation Damage of a Glass-Bonded Zeolite Waste Form Using Ion Irradiation

1997 ◽  
Vol 481 ◽  
Author(s):  
B. G. Storey ◽  
T. R. Allen
Keyword(s):  
Long Range ◽  
Crystalline Phase ◽  
Spent Nuclear Fuel ◽  
Ion Irradiation ◽  
Fission Products ◽  
Small Region ◽  
High Energy ◽  
Radioactive Isotopes ◽  
Waste Form ◽  
Retention Capacity

ABSTRACTGlass-bonded zeolite is being considered as a candidate ceramic waste form for storing radioactive isotopes separated from spent nuclear fuel in the electrorefming process. To determine the stability of glass-bonded zeolite under irradiation, transmission electron microscope samples were irradiated using high energy helium, lead, and krypton. The major crystalline phase of the waste form, which retains alkaline and alkaline earth fission products, loses its long range order under both helium and krypton irradiation. The dose at which the long range crystalline structure is lost is about 0.8 dpa for helium and 0.1 dpa for krypton. Because the damage from lead is localized in such a small region of the sample, damage could not be recognized even at a peak damage of 50 dpa. Because the crystalline phase loses its long range structure due to irradiation, the effect on retention capacity needs to be further evaluated.

scholarly journals A Review of Radiation Effects in Solid Nuclear Waste Forms

1983 ◽  
Vol 60 (2) ◽  
pp. 178-198 ◽  
Author(s):  
William J. Weber ◽  
Frank P. Roberts
Keyword(s):  
Nuclear Waste ◽  
Radiation Effects ◽  
Waste Forms ◽  
Nuclear Waste Forms

scholarly journals Microstructure and Leaching Characteristics of a Technetium Containing Metal Waste Form

1999 ◽  
Vol 556 ◽  
Author(s):  
S. G. Johnson ◽  
D. D. Keiser ◽  
M. Noy ◽  
T. O'Holleran ◽  
S. M. Frank
Keyword(s):  
Stainless Steel ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Fission Products ◽  
Point Of View ◽  
Waste Form ◽  
Nominal Composition ◽  
Spent Fuel ◽  
Waste Forms ◽  
Metal Waste

AbstractArgonne National Laboratory is developing an electrometallurgical treatment for spent fuel from the experimental breeder reactor II. A product of this treatment process is a metal waste form that incorporates the stainless steel cladding hulls, zirconium from the fuel and the fission products that are noble to the process, i.e., Tc, Ru, Pd, Rh, Ag. The nominal composition of this waste form is stainless steel/15 wt% zirconium/ 1–4 wt% noble metal fission products. The behavior of technetium is of particular importance from a disposal point of view for this waste form due to its long half life, 2.14E5 years, and its mobility in groundwater. To address these concerns a limited number of spiked metal waste forms were produced containing Tc. These surrogate waste forms were then studied using scanning electron microscopy (SEM) and selected leaching tests.

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