NSUF 18-1471: Controlling the kinetics of radiation induced crystallization in nanoceramics by doping
Light water systems have been the leading technology in the nuclear industry since ’50. However, recent Fukushima events showed the necessity to reconsider this well-consolidated route. Problems related to the evolution of the fuel cladding during accidental conditions must be solved in order to improve the technology. To tackle this detrimental problem, different solutions have been proposed. Among these, the use of coatings deposited on ZIRLO® or Zircaloy seems one of the best option. Recently, at the Istituto Italiano di Tecnologia (IIT), a metallic coating of Chromium has been developed in collaboration with Westinghouse. Films deposited on top of nuclear grade ZIRLO® have been tested inside Westinghouse autoclaves, showing encouraging results. Metallic Cr-based coatings could solve problems related to oxidation up to 600°C. Nevertheless, above this temperature, the stability of the metallic matrix is not guaranteed and Chromium atoms could diffuse through the interface forming eutectic alloys and low-melting intermetallics. To prevent the diffusion at extremely high temperature further addition must be taken in account. Another possible solution to overcome these issues is connected to the development of fast breeder reactors. In the framework of new generation reactors, Lead Fast Reactors (LFRs) shine as one of the most promising concept. One of the key limitations of design of heavy liquid metals (HLMs) technologies regards the ability of structural steels to withstand corrosion at high temperature (above 500°C). Again, coatings are recognized as one of the most promising strategies. In the last years, researches have studied an amorphous-nanocrystalline Al2O3 coating produced by Pulsed Laser Deposition (PLD) for HLMs-cooled nuclear systems. Up to now, the results indicate that the PLD-grown Al2O3 is a suitable material for protecting steels in LFRs environment. Furthermore, these Al2O3 coatings have been already irradiated with different heavy ions in previous campaigns. The good response of PLD-grown Al2O3 coatings under reactors-relevant conditions makes them attractive not only for fast reactors but also as inter-diffusion layer for Zr-based claddings in LWRs. The goal of this work is the in-situ study of Al2O3 films and Al2O3-Cr tandem systems under ion irradiation. In respect to previous tests, the effect of lighter ions will be considered. Moreover, with the in-situ monitoring, new aspects will be evaluated: the interaction between Cr and ZIRLO® in the presence of a buffer layer, the evolution of the films during irradiation and the effect of doping on the radiation-induced crystallization of Al2O3. To gain control on the crystallization processes, amorphous-nanocrystalline Alumina will be doped with allocations of different nature. Species able to promote crystallization like Cr will be employed to accelerate the formation of alpha-Al2O3 (for supercritical water environment) while atoms which retard the phenomenon like Zr or lanthanides will be used to stabilize the amorphous counterpart for LFRs applications. Here, thin TEM foils obtained from coated samples will be irradiated with 1MeV Kr ions up to 20 dpa, in a temperature range from 360 to 800°C.
Additional Info
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| Abstract | Light water systems have been the leading technology in the nuclear industry since ’50. However, recent Fukushima events showed the necessity to reconsider this well-consolidated route. Problems related to the evolution of the fuel cladding during accidental conditions must be solved in order to improve the technology. To tackle this detrimental problem, different solutions have been proposed. Among these, the use of coatings deposited on ZIRLO® or Zircaloy seems one of the best option. Recently, at the Istituto Italiano di Tecnologia (IIT), a metallic coating of Chromium has been developed in collaboration with Westinghouse. Films deposited on top of nuclear grade ZIRLO® have been tested inside Westinghouse autoclaves, showing encouraging results. Metallic Cr-based coatings could solve problems related to oxidation up to 600°C. Nevertheless, above this temperature, the stability of the metallic matrix is not guaranteed and Chromium atoms could diffuse through the interface forming eutectic alloys and low-melting intermetallics. To prevent the diffusion at extremely high temperature further addition must be taken in account. Another possible solution to overcome these issues is connected to the development of fast breeder reactors. In the framework of new generation reactors, Lead Fast Reactors (LFRs) shine as one of the most promising concept. One of the key limitations of design of heavy liquid metals (HLMs) technologies regards the ability of structural steels to withstand corrosion at high temperature (above 500°C). Again, coatings are recognized as one of the most promising strategies. In the last years, researches have studied an amorphous-nanocrystalline Al2O3 coating produced by Pulsed Laser Deposition (PLD) for HLMs-cooled nuclear systems. Up to now, the results indicate that the PLD-grown Al2O3 is a suitable material for protecting steels in LFRs environment. Furthermore, these Al2O3 coatings have been already irradiated with different heavy ions in previous campaigns. The good response of PLD-grown Al2O3 coatings under reactors-relevant conditions makes them attractive not only for fast reactors but also as inter-diffusion layer for Zr-based claddings in LWRs. The goal of this work is the in-situ study of Al2O3 films and Al2O3-Cr tandem systems under ion irradiation. In respect to previous tests, the effect of lighter ions will be considered. Moreover, with the in-situ monitoring, new aspects will be evaluated: the interaction between Cr and ZIRLO® in the presence of a buffer layer, the evolution of the films during irradiation and the effect of doping on the radiation-induced crystallization of Al2O3. To gain control on the crystallization processes, amorphous-nanocrystalline Alumina will be doped with allocations of different nature. Species able to promote crystallization like Cr will be employed to accelerate the formation of alpha-Al2O3 (for supercritical water environment) while atoms which retard the phenomenon like Zr or lanthanides will be used to stabilize the amorphous counterpart for LFRs applications. Here, thin TEM foils obtained from coated samples will be irradiated with 1MeV Kr ions up to 20 dpa, in a temperature range from 360 to 800°C. |
| Award Announced Date | 2018-05-17T11:15:33.457 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Alina Zackrone, Wei-Ying Chen, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Fabio Di Fonzo |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1471 |