scholarly journals Modeling of Nuclear Waste Forms: State-of-the-Art and Perspectives

MRS Advances ◽  
2020 ◽  
Vol 5 (5-6) ◽  
pp. 213-222
Author(s):  
Piotr. M. Kowalski ◽  
Steve Lange ◽  
Guido Deissmann ◽  
Mengli Sun ◽  
Kristina O. Kvashnina ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
State Of The Art ◽  
Mixed Valence ◽  
Scientific Basis ◽  
Atomistic Simulations ◽  
Barrier Materials ◽  
Uranium Oxidation ◽  
Safety Case ◽  
Waste Repositories ◽  
Nuclear Waste Forms

ABSTRACTComputational modeling is an important aspect of the research on nuclear waste materials. In particular, atomistic simulations, when used complementary to experimental efforts, contribute to the scientific basis of safety case for nuclear waste repositories. Here we discuss the state-of-the-art and perspectives of atomistic modeling for nuclear waste management on a few cases of successful synergy of atomistic simulations and experiments. In particular, we discuss here: (1) the potential of atomistic simulations to investigate the uranium oxidation state in mixed-valence uranium oxides and (2) the ability of cementitious barrier materials to retain radionuclides such as 226Ra and 90Sr, and of studtite/metastudtite secondary peroxide phases to incorporate actinides such as Np and Am. The new contribution we make here is the computation of the incorporation of Sr by C-S-H (calcium silicate hydrate) phases.

scholarly journals State-of-the-art review of materials properties of nuclear waste forms.

1981 ◽  
Author(s):  
J. E. Mendel ◽  
R. D. Nelson ◽  
R. P. Turcotte ◽  
W. J. Gray ◽  
M. D. Merz ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
State Of The Art ◽  
Materials Properties ◽  
Waste Forms ◽  
Nuclear Waste Forms

scholarly journals Requirement of the assessment strategy for biosphere in mature safety cases for nuclear waste repositories – Finland case

2015 ◽  
Vol 79 (6) ◽  
pp. 1607-1612 ◽  
Author(s):  
A. T. K. Ikonen
Keyword(s):  
Nuclear Waste ◽  
Waste Disposal ◽  
Nuclear Waste Disposal ◽  
Vital Role ◽  
Simple Boundary ◽  
Safety Case ◽  
Safety Cases ◽  
High Level ◽  
Radionuclide Release ◽  
Waste Repositories

AbstractIn safety assessments for nuclear waste disposal, the biosphere is a completely open system, whereas the bedrock can be treated with comparably simple boundary conditions. The bedrock has a vital role in providing and maintaining favourable conditions for the waste, but the public interest tends to focus on the biosphere. More importantly, the bedrock groundwater does arrive from the biosphere. Also, the regulations usually set the safety criteria in terms of doses occurring in the biosphere. Thus, it is reasonable to address the biosphere as a part of the disposal system, performance of which should be described based on conceptual models that cover phenomena and processes controlling radionuclide release and transport. From these, the actual assessment models and data are expected to be derived based on high-level research and expertise obtained through empirical study. In this paper, the complexity expected of a biosphere assessment within a mature safety case is discussed through the example of the Finnish regulations and recent safety cases for nuclear waste disposal. Both elaborate and complex presentations and stylised approaches have their benefits, and a balance needs to be sought.

Changes of Selected Structural and Mechanical Properties of the Strzelin Granites As Induced By Thermal Loads / Wpływ Obciążeń Termicznych Na Zmiany Niektórych Strukturalnych I Mechanicznych Właściwości Granitów Strzelińskich

2012 ◽  
Vol 57 (4) ◽  
pp. 951-974 ◽  
Author(s):  
Andrzej Nowakowski ◽  
Mariusz Młynarczuk
Keyword(s):  
Mechanical Properties ◽  
Nuclear Waste ◽  
Structural Changes ◽  
Structural Parameters ◽  
Total Porosity ◽  
Fracture Network ◽  
Qualitative Description ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Waste Repositories

Abstract Temperature is one of the basic factors influencing physical and structural properties of rocks. A quantitative and qualitative description of this influence becomes essential in underground construction and, in particular, in the construction of various underground storage facilities, including nuclear waste repositories. The present paper discusses the effects of temperature changes on selected mechanical and structural parameters of the Strzelin granites. Its authors focused on analyzing the changes of granite properties that accompany rapid temperature changes, for temperatures lower than 573ºC, which is the value at which the β - α phase transition in quartz occurs. Some of the criteria for selecting the temperature range were the results of measurements carried out at nuclear waste repositories. It was demonstrated that, as a result of the adopted procedure of heating and cooling of samples, the examined rock starts to reveal measurable structural changes, which, in turn, induces vital changes of its selected mechanical properties. In particular, it was shown that one of the quantities describing the structure of the rock - namely, the fracture network - grew significantly. As a consequence, vital changes could be observed in the following physical quantities characterizing the rock: primary wave velocity (vp), permeability coefficient (k), total porosity (n) and fracture porosity (η), limit of compressive strength (Rσ1) and the accompanying deformation (Rε1), Young’s modulus (E), and Poisson’s ratio (ν).

scholarly journals Ab Initio Investigation of Helium Mobility in La2Zr2O7 Pyrochlore

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 667
Author(s):  
Yanxia Lu ◽  
Qing Peng ◽  
Chenguang Liu
Keyword(s):  
Nuclear Waste ◽  
Density Functional ◽  
Minimum Energy ◽  
Elastic Band ◽  
Waste Forms ◽  
Band Method ◽  
And Migration ◽  
High Level ◽  
Migration Pathways ◽  
Nuclear Waste Forms

The α-decay of incorporated actinides continuously produces helium, resulting in helium accumulation and causing security concerns for nuclear waste forms. The helium mobility is a key issue affecting the accumulation and kinetics of helium. The energy barriers and migration pathways of helium in a potential high-level nuclear waste forms, La2Zr2O7 pyrochlore, have been investigated in this work using the climbing image nudged elastic band method with density functional theory. The minimum energy pathway for helium to migrate in La2Zr2O7 is identified as via La–La interstitial sites with a barrier of 0.46 eV. This work may offer a theoretical foundation for further prospective studies of nuclear waste forms.

Using “radioparagenesis” to design robust nuclear waste forms

2010 ◽  
Vol 3 (1) ◽  
pp. 130-135 ◽  
Author(s):  
C. Jiang ◽  
B. P. Uberuaga ◽  
K. E. Sickafus ◽  
F. M. Nortier ◽  
J. J. Kitten ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Waste Forms ◽  
Nuclear Waste Forms
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