Nuclear power is stagnating during the last forty years, and very unevenly distributed among the nations. Difficulties in its implementation should obviously have natural causes. Thus, the only nuclide available for fission is ²³⁵U present in a meagre amount of 0.7%. The most abundant isotopes ²³²Th and ²³⁸U require two neutrons (n) to release energy, referred to as “fertile”. Most importantly, highly radioactive fragments (marked in red) form during the fission chain reaction. Moreover, these act as n scavengers/poisons. If stable isotopes (in black interval) were created in a chain reaction, setting free 10 to 20 n, most heavy nuclei could easily be split:

²³⁵₉₂U + ¹₀n → ^78-86,91₃₆Kr + ^130-138,142₅₆Ba + 3¹₀n + 200 MeV.

              Constant need to remove products adds controversy to nuclear energy. As nominally CO₂-free energy source, fission is currently under reconsideration in SMRs, with <5 MW to 300 MW output power, using U fuel enriched to 5-20% [1,2]. In public reports the benefits of SMRs are predominately underlined, at the same time downplaying costs of U mining, milling and enrichment, as well as those of chemical reprocessing and management of wastes. The talk will focus on these less profitable aspects of nuclear technology. We conclude that SMRs are preferable to the existing large reactors. About 100 designs of SMR are awaiting construction and testing [2]. Neutron production with accelerators would lead to near complete utilization of fertile atoms present in depleted U and used fuel rods, so the latter should not be buried deep underground irretrievably.

[1] https://en.wikipedia.org/wiki/Small_modular_reactor.

[2] Advances in Small Modular Reactor Technology Developments, 2022, 424 pp. https://aris.iaea.org/Publications/SMR_booklet_2022.pdf.

Physicum seminars are meant for a broad auditorium of physicists and materials scientists, as well as for interested people from other natural and exact sciences (including bachelor level students) and aim at introducing what is important and new in a certain field, or where a specific research direction has reached today.