Modular High-Temperature Helium-Cooled Nuclear Reactor with Spherical Fuel Elements for Electricity and Hydrogen Production

Филиппов, Г. А.; Bogoyavlenskii, R. G.; Ponomarev-Stepnoi, N. N.; Gol’tsev, A. O.

doi:10.1023/b:aten.0000030915.37320.26

Cited by 7 publications

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“…For a fixed fraction of the melt, the amount of fissioning material per unit volume of the nuclear reaction zone is constant, and only the isotopic composition and thickness of the layer change as a result of burnup. The operation of a natural nuclear reactor can be compared with a high-temperature reactor -feeding of fuel (from above) in the form of spherical fuel elements into the core [17].…”

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Nuclear Fission Chain Reactions of Nuclides in the Earth’s Core over Billions of Years

2005

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Numerical simulation is used to study the possibility of long-term chain nuclear reactions deep inside the Earth over 4 billion years. The active layer (the natural nuclear reactor operating on fast neutrons in lakes) can form when uranium oxides or carbides precipitate from a liquid layer onto the Earth's solid interior core. A mechanism of uranium concentration in the Earth's core is studied, experiments are performed, and it is shown that a nuclear chain reaction with breeding of fissioning nuclides could have occurred in such a layer. The basic neutron-physical characteristics of such a natural nuclear reactor are calculated. It most likely operates in a pulsed mode. The critical condition for the duration of the reaction is the power level. It is found that for certain optimal power this process in the Earth's core can last for more than 4 billion years up to the present time.The Earth emits more heat (~45 TW) than it could as a result of only cooling [1]. Additional heat (~40%) is released as a result of the decay of radionuclides. A substantial quantity of radioactive elements is found not only in the Earth's crust but also in the lower mantle [2]. The heat flux from the Earth's core due to cooling and crystallization of its material ranges from 5 to 10 TW [3]. It is known that because of the differences in the half-lives of 235 U and 238 U the fraction of the former nuclide decreases with time, and billions of years ago uranium contained more 235 U [4]. It follows from the present-day concentration of uranium in pitchblende that about 2 billion years ago and earlier, when the 235 U fraction exceeded 3%, a spontaneous fission chain reaction could have occurred in rich uranium deposits. In 1972, traces of a natural nuclear reactor were discovered in West Africa in a uranium deposit at Oklo (Gabon) [5]. Later about 20 reactor zones were found in the same region. Investigations of other locations of actinide concentration and operation of natural nuclear reactors, not only in the Earth's crust but also in the Earth's core, have been started [3,6,7].The yield of fission products, which migrate from the chain reaction zone and reach the Earth's surface, is analyzed to determine the characteristics of natural nuclear reactors. The ratio 3 He/ 4 He is instructive [3]. Approximately 1 of 10,000 fissions of actinides occurs not into two but three fragments, one of which is tritium, which after undergoing β decay converts into 3 He. Thus, the ratio 3 He/ 4 He in volcanic lava in Hawaii is almost 40 times higher than its value in the Earth's atmosphere. Data confirming these facts in other locations (actually over the entire Earth) exist [8]. Other fission products of the actinides from a natural nuclear reactor, which have reached volcanic lava, are also being studied. Electron antineutrinos, which arise as a result of the β decay of the fission products from fissioning of heavy nuclei during a nuclear chain reaction [9], can be anoth-

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Nuclear Fission Chain Reactions of Nuclides in the Earth’s Core over Billions of Years

2005

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Physical characteristics and problems of developing a sodium-cooled fast reactor as a source of high-potential thermal energy for hydrogen production and other high-temperature technologies

et al. 2009

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Hydrogen as an energy carrier will play a considerable role in the future structure of energy production when nuclear reactors will replace fossil fuels. Investigations performed in recent years have shown that the production of large quantities of energy with high efficiency can be accomplished on the basis of thermochemical cycles using reactors with coolant temperature at the exit from the core of about 900°C. A variant of such a fast reactor with sodium as the coolant is proposed. The main physical characteristics and the main problems which must be solved to build such a reactor are presented. According to its properties, this reactor will meet the modern requirements for nuclear and radiation safety. It can also be used in other promising high-temperature technologies, for example, high-efficiency production of electricity.According to modern ideas, reactors with coolant temperature ~900°C at the exit from the core will play a large role in the future structure of nuclear structure. They will make it possible to solve important problems such as the production of hydrogen in large quantities, making electricity production more efficient, and expanding the use of high-temperature technology in industry.High-temperature helium-cooled reactors are now being considered for this purpose. For example, designs of a modular thermal helium reactor GT-MHR [1] with gas-turbine energy conversion and a fast GFR [2] for use in hydrogen production using an iodine-sulfur water separation cycle without the formation of greenhouse gases are being developed in the USA and some other foreign countries. In our country, a group of enterprises at the forefront with the Russian Science Center Kurchatov Institute [3] has developed a technical proposal for developing an electrotechnical facility on the basis of a thermal high-temperature helium HTGR for a chemical-industrial process for steam conversion of methane or products of gasification of coal with a low calorific value.

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Cooling and Thermal Concepts

Joyce¹

2018

Nuclear Engineering

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Modular High-Temperature Helium-Cooled Nuclear Reactor with Spherical Fuel Elements for Electricity and Hydrogen Production

Cited by 7 publications

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Nuclear Fission Chain Reactions of Nuclides in the Earth’s Core over Billions of Years

Nuclear Fission Chain Reactions of Nuclides in the Earth’s Core over Billions of Years

Physical characteristics and problems of developing a sodium-cooled fast reactor as a source of high-potential thermal energy for hydrogen production and other high-temperature technologies

Cooling and Thermal Concepts

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