Management of Radioactive Waste Containing Graphite: Overview of Methods

Fuks, L.; Herdzik-Koniecko, Irena; Kiegiel, Katarzyna; Zakrzewska-Kołtuniewicz, Grażyna

doi:10.3390/en13184638

Cited by 19 publications

(6 citation statements)

References 24 publications

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“…A specific waste stream that is generated during the operation of HTGR and its associated activities is irradiated graphite [25]. Graphite acts as a moderator and reflector of neutrons, leading to the generation of great amounts of low radioactive but still long-lived radioactive material.…”

Section: The Types Of Waste Generated In Htgr Cyclementioning

confidence: 99%

Management of Radioactive Waste from HTGR Reactors including Spent TRISO Fuel—State of the Art

et al. 2022

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In light of the increasing demand for energy sources in the world and the need to meet climate goals set by countries, there is growing global interest in high temperature gas cooled reactors (HTGRs), especially as they are known to be inherently safe nuclear reactors. The safety of HTGRs results, among other, from the nature of the nuclear fuel used in them in the form of coated TRISO particles (tri-structural-isotropic) and the reduction of the total amount of radioactive waste generated. This paper reviews numerous methods used to ensure the sustainable, feasible management and long-term storage of HTGR nuclear waste for the protection of the environment and society. The types of waste generated in the HTGR cycle are presented as well as the methods of their characterization, which are important for long-time storage and final disposal. Two leading nuclear fuel cycle strategies, the once-through cycle (direct disposal or open cycle) and the twice-through cycle (recycling or partially closed cycle), are discussed also in relation to TRISO spent fuel. A short review of the possibilities of treatment of TRISO spent nuclear fuel from HTGR reactors is made.

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Section: The Types Of Waste Generated In Htgr Cyclementioning

confidence: 99%

Management of Radioactive Waste from HTGR Reactors including Spent TRISO Fuel—State of the Art

et al. 2022

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“…The main composition of graphite is carbon (C). In industry, graphite usually appears as an environmentally hazardous waste. , Several studies were held to analyze the effect of additional graphite in the cement. Cai et al found that the addition of graphite improved the strength and deformation resistance of the common Class G cement.…”

Section: Introductionmentioning

confidence: 99%

Effect of Graphite on the Mechanical and Petrophysical Properties of Class G Oil Well Cement

2023

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Casing cementing is one of the most crucial operations in the oil well drilling process since it determines the durability and stability of the well throughout its life. Different additives have been mixed into the oil well cement slurry to improve the properties of both the cement slurry and the solidified cement sheath. Graphite is a waste material with a huge potential to be utilized in cementing to improve the properties of the oil well cement and reduce the graphite waste content in the environment. This study intends to analyze the effect of graphite on alteration in properties of the cement compressive and tensile strength, Poisson’s ratio, Young’s modulus, porosity, and permeability for three days of curing. Based on the trend of the properties during the three days of curing, equations were established to describe the future change in cement properties with time. Two formulas of cement, the base (with no graphite) and graphite-based (with 0.2% by weight of cement graphite) were prepared in this study. The results showed that the graphite successfully increased the compressive strength, tensile strength, and Poisson’s ratio of the cement sheath, throughout the curing process. Young’s modulus was decreased after the incorporation of graphite which indicates an enhancement in cement resistance to shear forces. The porosity and permeability were also decreased indicating formation of a more densified cement sheath.

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“…In particular, first-generation nuclear fission reactors using graphite components as reflectors, moderators, and fuel matrixes have produced large quantities of radioactive carbonaceous waste during the process of decommissioning nuclear facilities. The radioactive graphite waste produced has been stored temporarily at the decommissioning sites, waiting for development of a reliable and safe decontamination technology for final disposal [1][2][3][4][5]. The radioactivity of graphite waste originates from the active radionuclides produced from the nuclear fission reaction and the irradiation of impurities adsorbed on the pore surfaces of the pure graphite matrix [1, [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Single-Phase Flow Model of a Screw Reactor for Decontamination of Radioactive Graphite Waste Using Surface Gasification

Yang

2022

Processes

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A screw reactor is a promising apparatus for decontaminating radioactive graphite waste by uniform gasification under ambient air. However, developing the design equation for a screw reactor is difficult due to the reactor’s fundamentally intricate gas and solid interactions. In this study, we performed three-dimensional computational fluid dynamics simulations to predict and characterize the graphite particles that flow through the screw reactor and are thermally gasified. This was done using the Eulerian single-fluid approach coupled with the experimentally established kinetic model for graphite gasification. The numerical results show that the counter-rotating flow, generated along the rotating screw of the reactor by the relative motion of the reactor wall to the rotating screw, mixes particles spatially and reduces their axial velocity. The diameter of the feed graphite particles can be reduced by as much as 28% depending on the screw rotating velocity and the temperature of the reactor shell, according to the conducted numerical calculations. These numerical simulations can be used to provide proper operating parameters for the laboratory-scale screw reactor by which to decontaminate radioactive graphite waste by gasifying the radiocarbons, together with a part of the graphite matrix, on the surface of the graphite particles.

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Management of Radioactive Waste Containing Graphite: Overview of Methods

Cited by 19 publications

References 24 publications

Management of Radioactive Waste from HTGR Reactors including Spent TRISO Fuel—State of the Art

Management of Radioactive Waste from HTGR Reactors including Spent TRISO Fuel—State of the Art

Effect of Graphite on the Mechanical and Petrophysical Properties of Class G Oil Well Cement

Single-Phase Flow Model of a Screw Reactor for Decontamination of Radioactive Graphite Waste Using Surface Gasification

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