A Neutron Source Based on Spherical Tokamak
Abstract
:1. Introduction
- (i).
- The non-thermal plasma scenario has been demonstrated as a solid tool for plasma operation, as record fusion power was obtained in the JET DTE2 campaign [7,8,9], and it was studied intensively on TFTR [10] and JET DTE1 [11]; the same scenario has been used to obtain a record ion temperature in ST40 in deuterium plasma [12]; it is the optimized scenario for low Q [13] operation.
- (ii).
- (iii).
- Using the previous points and the method described in Section 3, an elaboration of the scaling law, which gives the major radius versus the magnetic field, can be performed, leading to the determination of the plasma parameters of a Q = 1.5 ST neutron source (named ST180, R = 180 cm, Aspect Ratio A = 1.8, B = 4 T).
- (iv).
- Based on the plasma parameters determined, the layout of ST180 tokamak is determined, defining the structural components as well: due to the high neutron flux, the problem of shieldings, which are useful for protecting the superconducting magnets, is solved using (Zr(BH4)4,W) [16,17,18]. The pulse length evaluated from the available flux swing is 58 s, and possible continuous operation of ST180 in the chosen plasma scenario is only limited by the recharging time of the main solenoid.
- (v).
- The ST180 neutron source can be considered suitable for FFHR realization because, using the non-thermal scenario, it is optimized for low fusion gain factors.
- In Section 2, the non-thermal plasma scenario with a spherical tokamak with low fusion gain factor and a new confinement scaling law are introduced;
- In Section 3, the scaling laws for spherical tokamaks are obtained, and the results are used to determine the plasma parameters of a low gain spherical fusion reactor, named ST180, which is useful as neutron source;
- In Section 4, the fusion power of ST180 non-thermal plasma is evaluated;
- In Section 5, the radial build-up of ST180 is briefly described;
- In Section 6, conclusions are drawn.
2. Non-Thermal Plasma Scenario for Spherical Tokamaks
3. Scaling Law for Spherical Tokamak Fusion Reactors in Non-Thermal Supershot-like Scenario
- (i).
- The reactor is working at a value of Q0 = ni τE Ti, where ni is the ion density, Ti the ion temperature, and τE the energy confinement time given by Equation (1)
- (ii).
- The alpha particle slowing down time (τSD) must be less than the energy confinement time; i.e., τSD = ΛSD τE, where ΛSD << 1 is a number
- R = 1.8 m;
- A = 1.8;
- Ip = 6 MA;
- B = 4 T;
- N = 10·1019 m−3;
- n/<n> = 3.5;
- elongation k = 2.9;
- beam energy WB = 80 keV.
4. Fusion Power Evaluation for Non-Thermal Plasmas
5. Radial Build-Up of ST180
- The heating systems technology (ICRH and NBI) needed for ST180 has been already used for long time on all the fusion devices under operation;
- The (high temperature) superconducting magnet technology is available and can be used;
- The neutron flux evaluated for ST180 (3.24 × 1016 n/m2 s) is very close to the ITER value (1016–1018 n/m2 s) [31];
- Being a nuclear device close to the ITER class, the safety rules to be applied must be the same as ITER.
6. Conclusions
- A new energy confinement time for non-thermal plasmas is introduced for ST working in non-thermal plasma scenario;
- A new scaling law for spherical tokamaks is then obtained, linking the major radius with the magnetic field on the axis for STs with fusion gain factors, with QFus = 1, 1.5, and 2;
- From the scaling law, the values of the plasma parameters of a Q = 1.5 ST, named ST180, are obtained (for the first time);
- A new formula for the fusion power for non-thermal plasmas is derived and applied to the evaluation of the neutron flux of ST180;
- A preliminary layout of the ST180 is derived from the plasma parameters and the definition of the material for the shielding of the magnets is performed;
- Being a low Q device, ST180 can be built with technology which is available and has been demonstrated.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
- Murgo, S.; Lomonaco, G.; Orsitto, F.P.; Panza, F.; Pompeo, N. Parametrical Choice of the Optimized Fusion System for a FFHR. Energies 2024, 17, 5121. [Google Scholar] [CrossRef]
- Murgo, S.; Bustreo, C.; Ciotti, M.; Lomonaco, G.; Orsitto, F.P.; Piovan, R.; Pompeo, N.; Ricco, G.; Ripani, M.; Panza, F. RFP-MSR Hybrid Reactor Model for Tritium Breeding and Actinides Transmutation. Energies 2024, 17, 2934. [Google Scholar] [CrossRef]
- Murgo, S.; Ciotti, M.; Lomonaco, G.; Pompeo, N.; Panza, F. Multi-group analysis of Minor Actinides transmutation in a Fusion Hybrid Reactor. EPJ Nuclear Sci. Technol. 2023, 9, 36. [Google Scholar] [CrossRef]
- IAEA TECDOC. Development of Steady State Compact Fusion Neutron Sources; Final Report Vienna, 2022; Barbarino, M., Ed.; IAEA: Vienna, Austria, 1998. [Google Scholar]
- Orsitto, F.P. IAEA FEC 2023 London, Tritium Production in a Fusion-Fission Hybrid Reactor Based on a Spherical Neutron Source, Paper CN 1708. Available online: https://conferences.iaea.org/event/316/ (accessed on 29 December 2024).
- Orsitto, F.P.; Todd, T.N. Tokamaks as neutron sources for Fusion-Fission Hybrid Reactors: Analysis of design parameters and technology readiness levels. In Proceedings of the 3rd International Conference on Fusion Neutron for Fission (FUNFI3), Hefei, China, 19–21 November 2018; Pizzuto, A., Orsitto, F.P., Eds.; ENEA: Roma, Italy, 2019. ISBN 978-88-8286-384-5. [Google Scholar]
- Maslov, M.; Lerche, E.; Challis, C.; Hobirk, J.; Kappatou, A.; King, D.; Rimini, F.; de La Luna, E.; Monakhov, I.; Jacquet, P.; et al. T-rich scenario for the record fusion energy plasmas in JET DT. In Proceedings of the 64th APS Plasma Physics Division, Spokane, DC, USA, 17–21 October 2022. Paper BI01.00003. [Google Scholar]
- Lerche, E.; Maslov, M.; Jacquet, P.; Monakhov, I.; King, D.; Keeling, D.; Challis, C.D.; Van Eester, D.; Mantica, P.; Maggi, C.; et al. Fundamental ICRF heating of deuterium ions in JET-DTE2. AIP Conf. Proc. 2023, 2984, 03005. [Google Scholar]
- Maggi, C.F.; Abate, D.; Abid, N.; Abreu, P.; Adabonyan, O.; Afzal, M.; Ahmad, I.; Akhtar, M.; Albanese, R.; Aleiferis, S.; et al. Overview of T and D-T results in JET with ITER-like wall. Nucl. Fusion 2024, 64, 112012. [Google Scholar]
- Strachan, J.D.; Bell, M.G.; Bitter, M.; Budny, R.V.; Hawryluk, R.J.; Hill, K.W.; Hsuan, H.; Jassby, D.L.; Johnson, L.C.; LeBlanc, B.; et al. Neutron emission from TFTR supershots. Nucl. Fusion 1993, 33, 991. [Google Scholar] [CrossRef]
- Keilhacker, M.; Gibson, A.; Gormezano, C.; Lomas, P.J.; Thomas, P.R.; Watkins, M.L.; Andrew, P.; Balet, B.; Borba, D.; Challis, C.D.; et al. High Fusion Performance from deuterium-tritium plasmas in JET. Nucl. Fusion 1999, 39, 209. [Google Scholar] [CrossRef]
- McNamara, S.; Asunta, O.; Bland, J.; Buxton, P.; Colgan, C.; Dnestrovskii, A.; Gemmell, M.; Gryaznevich, M.; Hoffman, D.; Janky, F.; et al. Achievement of ion temperatures in excess of 100 million of degrees Kelvin in the compact high-field spherical tokamak ST40. Nucl. Fusion 2023, 63, 054002. [Google Scholar] [CrossRef]
- Jassby, D.L. Neutral Beam-driven tokamak fusion reactors. Nucl. Fusion 1977, 17, 309. [Google Scholar] [CrossRef]
- Orsitto, F.P.; Romanelli, M. Plasma Parameters of Compact Fusion Reactors using Similarity Scaling Laws of Spherical Tokamak Fusion Plasmas. In Proceedings of the 48th EPS Conference on Plasma Physics 2022, P5a.103. Online, 27 June–1 July 2022. [Google Scholar]
- Bell, M.G.; Arunasalam, V.; Barnes, C.W. An overview of TFTR Confinement with intense neutral beam heating. In Proceedings of the 12th IAEA, paper IAEA-CN-50/A-1-2, proceedings. Nice, France,, 12–19 October 1988; Volume 1, p. 27. [Google Scholar]
- Schoof, F.; Todd, T.N. Magnetic field and power consumption constraints for spherical tokamak power plants. Fusion Eng. Des. 2022, 176, 113022. [Google Scholar] [CrossRef]
- Hayashi, T.; Tobita, K.; Nakamori, Y.; Orimo, S. Advanced neutron shielding material using zirconium borohydride and zirconium hydride. J. Nucl. Mater. 2009, 386–388, 119–121. [Google Scholar] [CrossRef]
- Windsor, C.G.; Morgan, J.G. Neutron and gamma flux distributions and their implications for radiation damage in the shielded superconducting core of a fusion power plant. Nucl. Fusion 2017, 57, 11603. [Google Scholar] [CrossRef]
- Costley, A. On the fusion triple product and fusion power gain of tokamak pilot plants and reactors. Nucl. Fusion 2016, 56, 066003. [Google Scholar] [CrossRef]
- ITER Physics Basis, Nuclear Fusion 39. Ch 2 Confinement and Transport. 1999; p. 2206eq. Available online: https://www.afs.enea.it/vlad/Papers/ITERPBch299nf.pdf (accessed on 29 December 2024).
- Romanelli, M.; Orsitto, F.P. On similarity scaling of tokamak fusion plasmas with different aspect ratio. Plasma Phys. Control. Fusion 2021, 63, 125004. [Google Scholar] [CrossRef]
- Wesson, J. Tokamaks, 2nd ed.; Oxford University Press: Oxford, UK, 1997. [Google Scholar]
- Gryaznevich, M. Experiments on ST40 at high magnetic field. Nucl. Fusion 2022, 62, 042008. [Google Scholar] [CrossRef]
- Menard, J.E.; Gehardt, S.; Bell, M.; Balek, J.; Brooks, A.; Canik, J.; Chrzanowski, J.; Denault, M.; Dudek, L.; Gates, D.A.; et al. Overview of the physics and engineering design of NSTX upgrade. Nucl. Fusion 2012, 52, 083015. [Google Scholar] [CrossRef]
- Harrson, J.R.; Akers, R.J.; Allan, S.Y.; Allcock, J.S.; Allen, J.O.; Appel, L.; Barnes, M.; Ayed, N.B.; Boeglin, W.; Bowman, C.; et al. Overview of new MAST physics in anticipation of first results from MAST Upgrade. Nucl. Fusion 2019, 59, 112011. [Google Scholar] [CrossRef]
- Petrov, Y.V.; Gusev, V.K.; Sakharov, N.V.; Minaev, V.B.; Varfolomeev, V.I.; Dyachenko, V.V.; Balachenkov, I.M.; Bakharev, N.N.; Bondarchuk, E.N.; Bulanin, V.V.; et al. Overview of GLOBUS-M2 spherical tokamak results at the enhanced values of magnetic field and plasma current. Nucl. Fusion 2022, 62, 042009. [Google Scholar] [CrossRef]
- Kovari, M.; Kemp, R.; Lux, H.; Knight, P.; Morris, J.; Ward, D.J. “PROCESS”: A systems code for fusion power plants—Part 1: Physics. Fusion Eng. Des. 2014, 89, 3054. [Google Scholar] [CrossRef]
- Johner, J. Helios: A zero dimensional tool for next step and reactor studies. Fusion Sci. Technol. 2011, 59, 308. [Google Scholar]
- Available online: http://flair.web.cern.ch/flair/ (accessed on 29 December 2024).
- Zohm, H. On the minimum size of DEMO. Fusion Sci. Technol. 2010, 58, 613. [Google Scholar] [CrossRef]
- Kashaykin, P.F.; Tomashuk, A.L.; Vasiliev, S.A. Radiation resistance of single-mode optical fibres with view to in-reactor applications. Nucl. Mater. Energy 2021, 27, 100981. [Google Scholar] [CrossRef]
ST180 | ST40 [23] | NSTX [24] | MAST-U [25] | GLOBUS-M2 [26] | |
---|---|---|---|---|---|
R(m) | 1.8 | 0.4–0.6 | 0.68 | 0.7 | 0.36 |
A | 1.8 | 1.6–1.8 | 1.25 | 1.4 | 1.5 |
Ip (MA) | 6 | 2 | 1.4 | 2 | 0.4 |
B (T) | 4 | 3 | 0.3 | 0.8 | 0.8 |
Pext (MW) | 10 | 2 | 11 | 6 | 0.8 |
ST180 | |||||
---|---|---|---|---|---|
Plasma Parameters | Radial Build-Up | ||||
Q | 2 | Plasma Density [n/1 × 1019 m−3] | 8 | Gap LCMS-VV [m] | 0.05 |
R [m] | 1.8 | Plasma Current Ip [MA] | 4 | Vacuum Vessel Thickness [m] | 0.1 |
A | 1.8 | Pfus [MW] | 15 | Neutron shield (Zr(BH4)4,W) [m] | 0.25 |
B [T] | 4.28 | Neutron Source Intensity [1 × 1018·n/s] | 5 | Thermal Insulator [m] | 0.05 |
WB [keV] | 40 | PAUX [MW] | 7.5 | Total Inboard Thickness [m] | 0.45 |
ST180 | |
---|---|
Confinement time (s) | 2.42 |
Pulse length (s) | 58 |
q95 | 8.71 |
βN | 2.46 |
fCD | 0.05 |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Orsitto, F.P.; Burgio, N.; Ciotti, M.; Lomonaco, G.; Panza, F.; Santagata, A. A Neutron Source Based on Spherical Tokamak. Energies 2025, 18, 2029. https://doi.org/10.3390/en18082029
Orsitto FP, Burgio N, Ciotti M, Lomonaco G, Panza F, Santagata A. A Neutron Source Based on Spherical Tokamak. Energies. 2025; 18(8):2029. https://doi.org/10.3390/en18082029
Chicago/Turabian StyleOrsitto, Francesco P., Nunzio Burgio, Marco Ciotti, Guglielmo Lomonaco, Fabio Panza, and Alfonso Santagata. 2025. "A Neutron Source Based on Spherical Tokamak" Energies 18, no. 8: 2029. https://doi.org/10.3390/en18082029
APA StyleOrsitto, F. P., Burgio, N., Ciotti, M., Lomonaco, G., Panza, F., & Santagata, A. (2025). A Neutron Source Based on Spherical Tokamak. Energies, 18(8), 2029. https://doi.org/10.3390/en18082029