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- Moiseyenko, Volodymyr, et al.
(author)
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Americium and Curium Burnup in a Fusion Reactor
- 2021
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In: Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion. - : NRC Kurchatov Institute. - 0202-3822. ; 44:2, s. 133-138
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Journal article (peer-reviewed)abstract
- A large amount of spent nuclear fuel (SNF) from nuclear power plants has been accumulated globally to date, and there is still no established strategy for handling it. While SNF can be partitioned, the predominant isotope Uranium-238 can be used to produce secondary fuel in fast nuclear reactors, and plutonium be burned in thermal nuclear reactors as a part of MOX fuel. Fission products can be disposed in geological repositories, as they decay in 200—300 years — much sooner than SNF. A major challenge is to handle minor actinides (MAs), particularly americium and curium, which are long-lived elements and are currently not recycled. They have different nuclear properties and cannot be treated like plutonium. It is possible to have americium and curium effectively burned up (fissioned) through irradiation with fusion neutrons. This paper explores the idea of employing fusion power plants for recycling those elements. An appropriate model was generated, which used americium and curium quantities small enough to avoid any strong impact on the reactor systems and operation. At the same time, the model allowed for high MA burnup rates. Nuclear facility used in the model was a torus-shaped thermonuclear reactor with plasma major and minor radii of 1000 and 300 cm, respectively. Such facility could take up additional 10 t of fuel (americium plus curium) with no significant impact on its physical characteristics. The americium and curium burnup rates, calculated with the MNCPX code, were within acceptable limits. Fission neutrons were found to contribute to the production of tritium, which may be important from the standpoint of the reactor’s self-sufficiency in tritium supply. Calculations proved that the reactivity of the reactor as a fission burner was low, enabling a safe operation. In addition to the MA incineration and tritium breeding capacities, fission reactions provided for a moderate (tens of percent) power gain.
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| 2. |
- Moiseyenko, Volodymyr, et al.
(author)
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Developments for stellarator-mirror fusion-fission hybrid concept
- 2021
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In: Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion. - : NRC Kurchatov Institute. - 0202-3822. ; 44:2, s. 111-117
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Journal article (peer-reviewed)abstract
- Conceptual development activities on a stellarator-mirror-based fission-fusion hybrid system (SM hybrid) are reviewed. Intended fortransmutation of spent nuclear fuel and safe fission energy production, SM hybrid consists of a fusion neutron source and a powerful subcritical fast fission reactor core. Its fusion component is a stellarator with an embedded magnetic mirror. The stellarator allows for theconfinement of a moderately hot (1—2 keV) deuterium plasma. In the magnetic mirror, the hot sloshing tritium ions are trapped andfusion neutrons are generated. The magnetic mirror is surrounded by a fission mantle, where transmutation of minor actinides and energygeneration take place. One candidate magnetic confinement device for the SM hybrid is the advanced DRACON magnetic trap system,which, unlike the «classical» DRACON version, has one short, rather than two longer mirrors with a relatively short size of 3—6 m. Acomparative numerical analysis of collisionless losses occurring in the magnetic trap part of the single-mirror DRACON leads to a conclusion about the possibility for high-energy tritium ions to be fairly well confined in the magnetic trap area. The Uragan-2M (U-2M)stellarator is used to test the SM hybrid concept with experiment. To fit a magnetic trap into U-2M system, one of the toroidal coils hadto be switched off. A radial escape of charged particles may spontaneously give rise to a weak radial electric field, which may result inclosing the particles’ drift trajectories and thereby substantially improve their confinement. Background plasma confinement withoutdestructive instabilities is demonstrated in the stellarator-mirror regime of U-2M) operation. The sloshing ions driven by radio-frequencyheating are detected in the mirror part of the device with NPA diagnostics. A novel fission mantle design for the SM hybrid is proposed.
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| 3. |
- Ågren, Olov, et al.
(author)
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3d coils for a compact min B mirror field with minimal flux tube ellipticity
- 2021
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In: Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion. - : NRC Kurchatov Institute. - 0202-3822. ; 44:2, s. 118-123
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Journal article (peer-reviewed)abstract
- We determine coil arrangements for reproducing a minimum-B mirror magnetic field, optimized with respect to plasma stability, plasma cross-section ellipticity and particle drift surfaces. The reproduction has to be done with precision, as field errors may give rise to plasma instabilities or collisionless plasma losses due to the guiding centres’ drift away from the confinement region. We have developed a set of twisted «fishbone» coils to allow an array of coils to be flexibly stacked, as required for a precise magnetic field reproduction. Results suggest that high mirror ratios of around 10 can be obtained using a fishbone coil arrangement. The mirror ratio can be further increased by finite plasma beta. Parameters representative of a compact 10 MW fusion neutron source have been derived.
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