Refinment of a decontamination technology for radioactively contaminated equipment

Shelenkova, Veronika V.; Kulagina, Tatiana A.

doi:10.25283/2587-9707-2021-1-28-38

Cited by 5 publications

(2 citation statements)

References 6 publications

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“…As a result of decontamination, a wide range and quantity of radioactive waste can be produced, therefore the optimisation of decontamination technologies is a very important issue not only for radiation protection aspects, but in case of radioactive waste management too, to reduce the volumes of secondary wastes generated and/or allow for further processing. (Valencia, 2012;Deng et al, 2020;Shelenkova and Kulagina, 2021). According to the (World Nuclear Waste Report, 2019) 1.4 million m 3 of radioactive wastes will be created by the decommissioning of nuclear facilities in Europe (World Nuclear Waste Report, 2019).…”

Section: Introductionmentioning

confidence: 99%

Optimisation of the chemical oxidation reduction process (CORD) on surrogate stainless steel in regards to its efficiency and secondary wastes

Rivonkar¹,

Katona²,

Robin³

et al. 2022

Front. Nucl. Eng.

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Nuclear Power is a decarbonated technology of electrical energy generation. Using nuclear energy as a power source is currently considered as the best option in the fight against climate change. But the radioactive waste generated from nuclear power plants and their related facilities are matter of concern. Though the high level and intermediate level activity wastes are contained in small volumes (≤10%), significant volumes of lower activity wastes are generated. Metallic wastes are a major component of these radioactive wastes with about 500,000 tons expected in France alone, including 130,000 tons from steam generators. Majority of these metals are made of Stainless steel 316 alloy or Inconel 600. Under the effect of the primary circuit thermal-hydraulic constraints and irradiation, these the resulting corrosion products may be activated when close to the fuel, and be transported throughout the circuit. These products can be deposited on the surface of other metal components, causing contamination of the latter. The contamination can be adsorbed on the surface but can also diffuse in the oxide layers and sub-surface. The oxide layer is composed of an inner layer of Cr oxide under a layer of Ni and Fe oxide. Chemical decontamination is preferred due to the possibility of decontamination of difficult geometries and tube bends. In order to decontaminate these materials, it is important to dissolve the oxide layers chemically and a few micrometers of base metal where it could have diffused. An existing chemical method used to treat these materials is studied in this article, Chemical Oxidation Reduction Decontamination (CORD). Surrogate steel samples were prepared using high temperature induction heating and water vapour after sample preparation and cleaning. The oxide layer was characterised before treatment of the samples in the batch method at different concentrations and its effects are observed on the dissolution of the oxide layers. A protocol is being developed for the treatment of secondary waste effluents by multi-stage precipitation with a goal to reduce the total waste volumes and thus the volumes of ion exchange resins that would otherwise be needed.

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Section: Introductionmentioning

confidence: 99%

Optimisation of the chemical oxidation reduction process (CORD) on surrogate stainless steel in regards to its efficiency and secondary wastes

Rivonkar¹,

Katona²,

Robin³

et al. 2022

Front. Nucl. Eng.

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“…Various decontamination technologies have been developed and implemented to address these challenges. These technologies not only enhance workplace safety but also have implications for radioactive waste management by minimizing the generation of secondary waste and allowing for further processing (Valencia, 2012;Deng et al, 2020;Shelenkova and Kulagina, 2021). As a result of decontamination efforts, a wide range and significant quantities of secondary radioactive waste can be generated.…”

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confidence: 99%

Optimized precipitation process for the treatment of radioactive effluents from Ni-alloy decontamination using a chemical oxidation reduction process

Robin,

Rivonkar,

Suzuki-Muresan

et al. 2024

Front. Nucl. Eng.

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Nuclear power plays a major role in the generation of electricity with low carbon emissions. However, it generates significant amounts of radioactive waste, mainly from contaminated metallic components such as steam generators. Decontamination is essential for the safe handling and eventual recycling or disposal of these materials. Various decontamination techniques can be utilized but chemical processes are recommended for complex geometries such as the tubular parts of steam generators. COREMIX (Chemical Oxidation REduction using nitric permanganate and oxalic acid MIXture) is a process that is similar to the CORD (Chemical Oxidation Reduction Decontamination) process currently utilized in the industry which involves dissolving the contaminated oxide layers from metallic surfaces. This process generates a large quantity of radioactive effluent that requires appropriate treatment. The objective is to reduce metallic concentration and the radioactivity by precipitating metals in solution as hydroxides M(m-n)(OH)n (with m the oxidation number of the metal M). The optimization of a two-step precipitation protocol is presented here, with a study of the contact time (1–24 h) and the reagents used (NaOH and KOH). The resulting precipitates from this process are characterized using several techniques (FTIR, TGA and XRD). Tests were conducted on surrogate samples to demonstrate the viability of the process on more complex samples. Finally, the optimized protocols were implemented on radioactive Ni-alloy samples. Decontamination factors were calculated portraying the efficiency of both the COREMIX and the subsequent two-stage precipitation process. Characterization of the sludge produced during the process shows that the precipitate obtained at pH 8.5 consists mainly of iron (III) oxide-hydroxides, whereas the precipitate obtained at pH 12 is mainly composed of manganese (II,III) oxide. The optimization steps show that the contact time during the first precipitation and the choice of precipitants does not influence the efficiency of the protocol while the destruction of oxalic acid proves to be critical to quantitatively precipitate chromium. Ultimately, the COREMIX process can effectively decontaminate contaminated Ni-alloy samples, removing between 12% and 14% of the contamination in each cycle. Decontamination of effluent using the precipitation protocol results in a very high decontamination factor of between 3000 and 6000.

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Development of the circumpolar territories of the Russian Federation

2021

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This article considers the possibility of sustainable development of the eastern territories of Russia from the Ural to the Pacific Ocean, which concentrate the overwhelming part of the country’s natural resources. An approach for the development of economic policy, making optimal economic decisions in the field of assessing the prevented damage is presented. It is noted that the underestimation of environmental parameters leads to a distortion of the analysis of economic development through traditional indicators of the gross national product, etc., the growth of which may cover the environmental degradation. A new method for assessing the prevented economic damage during environmental protection measures was proposed, which takes into account various technical and design features of dust cleaning systems. By using the proposed methodology it seems possible to assess the expected damage to the environment, the economic efficiency of the project being developed, and select the most profitable area for the location of dust-cleaning equipment at the design stage. A criterion for evaluating the effectiveness when comparing installations of various designs were proposed.

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Refinment of a decontamination technology for radioactively contaminated equipment

Cited by 5 publications

References 6 publications

Optimisation of the chemical oxidation reduction process (CORD) on surrogate stainless steel in regards to its efficiency and secondary wastes

Optimisation of the chemical oxidation reduction process (CORD) on surrogate stainless steel in regards to its efficiency and secondary wastes

Optimized precipitation process for the treatment of radioactive effluents from Ni-alloy decontamination using a chemical oxidation reduction process

Development of the circumpolar territories of the Russian Federation

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