• Energy Research

We investigated induction of chromosome aberrations (CA) in human lymphocytes when exposed to 150 MeV and spread out Bragg peak (SOBP) proton beams, and 199 MeV/u carbon beam which are currently widely used for cancer treatment and simultaneously are important components of cosmic radiation. For a comparison, the boron ions of much lower energy 22 MeV/u and a 60Co γ rays were used. Dose-effect curves as well as the distributions of CA were studied using Poisson and Neyman type A statistics. Systematics of experimentally determined parameters, their dependence on applied doses and irradiation quality are presented.

The EROI (Energy Returned On Invested) has been calculated for various systems, especially power plants, applying several different methodologies. This quantity is often used as an argument in discussions about economics to emphasize the performance of a certain technology. Contrary to that, the publications often answer different questions,e.g.analyses of emissions or material flows, rendering the EROI unphysical. The present work introduces a physical approach based on exergy flows for EROI calculation to pinpoint and compare the efficiency of different power plant technologies.

This study is based on our already published experimental data (Kowalska et al. in Radiat Environ Biophys 58:99-108, 2019) and is devoted to modeling of chromosome aberrations in human lymphocytes induced by 22.1 MeV/u 11B ions, 199 MeV/u 12C ions, 150 MeV and spread-out Bragg peak (SOBP) proton beams as well as by 60Co γ rays. The curvature of the dose-effect curves determined by the linear-quadratic model was considered in the frame of a simple analytical approach taking into account increase in the irradiation dose due to overlapping interaction regions of ion tracks. The model enabled to estimate effective interaction radius which could be compared with the physical expectations. The results were also compared to the Amorphous Track Structure Model of Katz which allows to get some additional information about the ion track structure. The analysis showed that the curvature of the experimental dose-effect curves mainly results from highly efficient repair processes of the DNA damage.

This study presents the design and computational fluid dynamics (CFD) analysis of a mini demonstrator for a dual fluid reactor (DFR). The DFR is a novel concept currently under investigation. The DFR is characterized by the implementation of two distinct liquid loops dedicated to fuel and coolant. It integrates the principles of molten salt reactors and liquid metal cooled reactors; thus, it operates in a high temperature and fast neutron spectrum, presenting a distinct approach in the field of advanced nuclear reactor design. The mini demonstrator serves as a scaled-down version of the actual reactor, primarily aimed at gaining insights into the CFD analysis intricacies of the reactor while minimizing computational costs. The CFD modeling of the MD intends to add valuable data for the purpose of modeling validation against experiments to be conducted on the MD. These experiments can be used for DFR licensing and design optimization. The coolant and fuel utilized in the mini demonstrator are of low Prandtl number (Pr = 0.01) liquid lead, operating at two distinct inlet temperatures, namely 873 K and 1473 K. The study showed a rapid increase in turbulence due to intense mixing and abrupt changes in flow areas and directions, despite the relatively low inlet velocities. Hot spots characterized by elevated temperatures were identified, analyzed, and justified based on their spatial distribution and flow conditions. Flow swirling within pipes was identified and a remedy approach was suggested. Inconsistent mass flow rates were observed among the fuel pipes, with higher rates observed in the lateral pipes. Although lower fuel temperatures were observed in the lateral pipes, they consistently exhibited higher heat exchange characteristics. The study concludes by giving physical insights into the heat transfer and flow behavior, and proposing design considerations for the dual fluid reactor to enhance structural safety and durability, based on the preliminary analysis conducted.

The energy returned on invested, EROI, has been evaluated for typical power plants representing wind energy, photovoltaics, solar thermal, hydro, natural gas, biogas, coal and nuclear power. The strict exergy concept with no “primary energy weighting”, updated material databases, and updated technical procedures make it possible to directly compare the overall efficiency of those power plants on a uniform mathematical and physical basis. Pump storage systems, needed for solar and wind energy, have been included in the EROI so that the efficiency can be compared with an “unbuffered” scenario. The results show that nuclear, hydro, coal, and natural gas power systems (in this order) are one order of magnitude more effective than photovoltaics and wind power.

Abstract The Dual Fluid Reactor, DFR, is a novel concept of a fast heterogeneous nuclear reactor. Its key feature is the employment of two separate liquid cycles, one for fuel and one for the coolant. As opposed to other liquid-fuel concepts like the Molten-Salt Fast Reactor (MSFR), both cycles in the DFR can be separately optimized for their respective purpose, leading to advantageous consequences: A very high power density resulting in remarkable cost savings, and a highly negative temperature feedback coefficient, enabling a self-regulation without any control rods or mechanical parts in the core. In the current reference design the fuel liquid is an undiluted actinide trichloride based on isotope-purified Cl-37, circulating at an operating temperature of 1000 °C. It can be processed on-line in a small internal processing unit utilizing fractional distillation or electro refining. Medical radioisotopes like Mo-99/Tc-99m are by-products and can be provided right away. In a more advanced design, an actinide metal alloy melt with an appropriately low solidus temperature is also possible which enables a reduction of the core size and allows a further increase in the operating temperature due to its high heat conductivity. For the reference design, pure Lead as coolant is the best choice. It yields a very hard neutron spectrum, fostering a very good neutron economy and therefore making the DFR a preferred thorium breeder but also a very effective waste incinerator and transmuter. With its high coolant temperature the DFR achieves the same ambitions as the Generation IV concept of the very high temperature reactor (VHTR), with all its advantages like electricity production with high efficiency and the synthesis of carbon-free fuels, but with overall production costs competitive with today’s refined oil. The specific combination of the liquids in the very high temperature regime requires structural materials withstanding corrosive attacks. Because of the small size of the reactor core the utilization of these expensive materials would have no significant impact on the overall energy (and also economic) efficiency, measured by the EROI (Energy Return on Investment), which is more than 20 times higher than for a light-water reactor (LWR). The DFR inherits the positive properties of the lead-cooled reactor (LFR) and of the MSFR, especially its outstanding passive safety features.