Nuclear Burning Wave Reactor
Sergii FOMIN
Akhiezer Institute for Theoretical Physics
National Science Center “Kharkov Institute of Physics & Technology”, Kharkov, Ukraine
V.N. Karazin National Kharkiv University
A fast breeder reactor operating in the self-sustaining nuclear burning wave mode1-7 (NBW) is one of the most promising concepts for nuclear fission systems. The unique features of this mode, which ensure the reactor's intrinsic safety at the deepest level, are based on the absence of reactivity margins throughout its entire reactor campaign, as well as on a specific negative reactivity feedback mechanism. Critical conditions in such a reactor are maintained automatically, without any external reactivity control. Fuel for the NBW reactor, except its startup, can be natural or even depleted uranium and thorium, thereby solving the problem of nuclear energy fuel resources for thousands of years to come. Such a reactor can operate for decades without refueling, eliminating the risks of radiation accidents and theft of fissile materials during nuclear fuel transportation and reprocessing. The ability to "afterburn" long-lived radioactive waste (MA) from other reactors could help solve one of the most important environmental problems in nuclear energy.
Significant contribution to the development of this concept using different approaches was made by Lev Feoktistov1, Edward Teller2, Hiroshi Sekimoto3, and others. The privet company TerraPower created with financial support from Bill Gates4 has ambitious plan for the practical realization of this concept called the Traveling Wave Reactor.
In contrast to the aforementioned works, which focused on the study of steady-state of the NBW mode1,3 or attempts of direct Monte Carlo simulation2, we developed an original deterministic approach5-7, which gives a possibility of investigations transient processes during reactor startup, its forced shutdown, and subsequent restart, as well as to study the stability of the NBV regime. Our approach is based on the numerical solution of the non-stationary equation of neutron diffusion in a multiplying medium, along with a set of burnup equations for fuel components and nuclear kinetics equations for delayed neutron precursor nuclei. Recently, we proposed a method for controlling the power of such a reactor by varying the efficiency of its radial reflector. This presentation invites discussion of the following topics:
• The physical nature of slow nuclear burning phenomenon
• Various approaches to describing nuclear burning wave
• Our computational model and FANTENS-2D code
• Results of our calculations and main features of the NBW reactor
• Stability of the NBW mode and a special mechanism of the negative reactivity feedback
• Power control of the NBW reactor: transient processes at startup, shutdown and restart
• Unsolved problems and possible solutions
References
1. L.P. Feoktistov. Preprint IAE-4605-4, 1988; Sov. Phys. Doklady, 34 (1989) 1071.
2. E. Teller. Nuclear Energy for the Third Millennium. Preprint UCRL-JC-129547, LLNL, 1997.
3. H. Sekimoto, K. Ryu, Y. Yoshimura. Nucl. Sci. Engin. 139 (2001) 306.
4. Bill Gates, TED, February 12, 2010. http://www.ted.com/talks/bill_gates.html
5. S. Fomin et al. Annals of Nuclear Energy, 32 (2005) 1435; 148 (2020) 107699.
6. S. Fomin et al. Progress in Nuclear Energy, 50 (2008) 163; 53 (2011) 800.
7. S. Fomin et al. Proceedings of the Int. Conf. “Global 2009” Paper 9456; “Global 2015” Paper 5254. Proceedings of the IC ”Fast Reactors and Related Fuel Cycle” Paper CN-199-457 (2013); Paper CN-291-365 (2022); Paper CN-343-79 (2026).