Mobilization and Management of Tellurium in Severe Accident Scenarios
Doktorsavhandling, 2022
Safety is one of the highest priorities in any industry. In the nuclear industry, safety is in the essence since in case of a nuclear accident, the consequences can be long-lasting, hazardous, and devastating to the public, environment, and the industry. Although only two accidents of highest significance have occurred, their influence is still present today. One of the most severe consequences of a severe nuclear reactor accident is the release of radioactive material to the environment. Different characteristics, such as volatility, toxicity, and half-life, of the released elements determine their effect and significance. Among the released radionuclides is tellurium. The tellurium isotopes released in the major accidents are highly volatile and have half-lives long enough to make tellurium important especially in the early stages of an accident. The released tellurium isotopes can cause increased radiation dose to the public during the first weeks after the accident. Moreover, many of the tellurium isotopes released decay to iodine isotopes which is also a concern due to the increased risk of thyroid cancer iodine can cause.
The aim of this work was to investigate phenomena involving tellurium occurring inside the containment building during a severe nuclear accident. The work is divided into mobilization of tellurium species and their management. The results obtained in this research provide valuable information on the behavior of tellurium in severe accident scenarios. The reactions leading to increased solubility and volatility were shown. High emphasis was put on the formation, stability, and mitigation of organic tellurides. The formation of a variety of organic tellurides from paint solvents under gamma irradiation was observed. This causes concerns about possible re-volatilization leading to post-accident releases. In addition to the increased mobility, this work provides information on the mitigation of tellurium species in accident scenarios. The containment spray system was found to be relatively effective in removing tellurium species from the containment atmosphere. In addition, activated charcoal materials trapped dimethyl telluride well. However, some reversibility was observed which raises interest on the adsorption mechanism. The results presented in this work lay the foundation for further studies on tellurium behavior in the containment. The evidence showing the formation of organic tellurides is especially significant since that could potentially lead to increased releases.
The aim of this work was to investigate phenomena involving tellurium occurring inside the containment building during a severe nuclear accident. The work is divided into mobilization of tellurium species and their management. The results obtained in this research provide valuable information on the behavior of tellurium in severe accident scenarios. The reactions leading to increased solubility and volatility were shown. High emphasis was put on the formation, stability, and mitigation of organic tellurides. The formation of a variety of organic tellurides from paint solvents under gamma irradiation was observed. This causes concerns about possible re-volatilization leading to post-accident releases. In addition to the increased mobility, this work provides information on the mitigation of tellurium species in accident scenarios. The containment spray system was found to be relatively effective in removing tellurium species from the containment atmosphere. In addition, activated charcoal materials trapped dimethyl telluride well. However, some reversibility was observed which raises interest on the adsorption mechanism. The results presented in this work lay the foundation for further studies on tellurium behavior in the containment. The evidence showing the formation of organic tellurides is especially significant since that could potentially lead to increased releases.
nuclear
gamma irradiation
source term
severe accident
tellurium
10:an, Kemigården 4, Chalmers
Opponent: Professor Clara Wren, Chemistry Department, Western University, Ontario, Canada
Författare
Anna-Elina Pasi
Chalmers, Kemi och kemiteknik, Energi och material
Organic Telluride Formation from Paint Solvents Under Gamma Irradiation
Nuclear Technology,;Vol. In Press(2022)
Artikel i vetenskaplig tidskrift
Tellurium retention by containment spray system
Annals of Nuclear Energy,;Vol. 164(2021)
Artikel i vetenskaplig tidskrift
Tellurium Behavior in the Containment Sump: Dissolution, Redox, and Radiolysis Effects
Nuclear Technology,;(2020)p. 1-11
Artikel i vetenskaplig tidskrift
Tellurium transport in the RCS under conditions relevant for severe nuclear accidents
Progress in Nuclear Energy,;Vol. 139(2021)
Artikel i vetenskaplig tidskrift
Pasi, A. E., Foreman, M. R. S. J., & Ekberg, C. Study of the Removal Efficiency of Activated Charcoals for Organic Tellurides
Radiolytic degradation of dimethyl telluride in aqueous solutions
Radiation Physics and Chemistry,;Vol. 207(2023)
Artikel i vetenskaplig tidskrift
Nuclear power has been an important source of electricity for decades. Low carbon emissions, stable and high production of energy make nuclear power an appealing option to not only battle climate change but also the current energy crisis. However, one of the major drawbacks of the use of nuclear energy is the possibility for an accident, and the devastating consequences it can cause. Severe nuclear reactor accidents that have occurred, one might say in regular intervals, have raised great concerns about the safety of nuclear power. The consequences of a severe accident can be extremely severe and far-reaching including increased risk of thyroid cancer due to radioiodine, restricted use of highly contaminated area and phycological consequences caused by evacuation and lack of communication. However, the accidents have also led to major improvements and better understanding of accident progression and other phenomena occurring inside the reactor building. This again has led to more efficient management systems, better communication, and overall improvement of the safe use of nuclear power.
In severe accident scenarios, the highest activity of the radionuclides released comes from the most volatile fission products, noble gases, iodine, cesium, and tellurium. In addition to the radioactivity, other factors such as health consequences, half-life or toxicity increase the significance of the released elements. One of the significant radionuclides released is tellurium. The main tellurium isotopes released in an accident scenario have half-lives of a few days, making them important in the early stages of the accident. In addition, many of the tellurium isotopes decay to iodine. This further increases the significant since tellurium can indirectly contribute to the risk of thyroid cancer via its daughter nuclides.
In this work, the phenomena involving tellurium occurring inside the containment building during a severe nuclear accident were investigated. The work is divided into two parts: reaction leading to mobilization of tellurium species and their management. High emphasis was put on the formation, behavior and trapping of organic tellurides, extremely volatile species potentially leading to increased releases. The results obtained in this research provide knowledge on the behavior of different tellurium species inside the containment. This work paves the way for further studies on tellurium in severe accident scenarios, especially those focusing on organic tellurides.
In severe accident scenarios, the highest activity of the radionuclides released comes from the most volatile fission products, noble gases, iodine, cesium, and tellurium. In addition to the radioactivity, other factors such as health consequences, half-life or toxicity increase the significance of the released elements. One of the significant radionuclides released is tellurium. The main tellurium isotopes released in an accident scenario have half-lives of a few days, making them important in the early stages of the accident. In addition, many of the tellurium isotopes decay to iodine. This further increases the significant since tellurium can indirectly contribute to the risk of thyroid cancer via its daughter nuclides.
In this work, the phenomena involving tellurium occurring inside the containment building during a severe nuclear accident were investigated. The work is divided into two parts: reaction leading to mobilization of tellurium species and their management. High emphasis was put on the formation, behavior and trapping of organic tellurides, extremely volatile species potentially leading to increased releases. The results obtained in this research provide knowledge on the behavior of different tellurium species inside the containment. This work paves the way for further studies on tellurium in severe accident scenarios, especially those focusing on organic tellurides.
Infrastruktur
Chalmers infrastruktur för masspektrometri
Styrkeområden
Energi
Ämneskategorier
Kemiteknik
Kemi
ISBN
978-91-7905-736-7
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5202
Utgivare
Chalmers
10:an, Kemigården 4, Chalmers
Opponent: Professor Clara Wren, Chemistry Department, Western University, Ontario, Canada