On Nanoceramic Fuel for Perspective Nuclear Reactors

Author(s):  
Pavel N. Alekseev ◽  
Alexander A. Proshkin ◽  
Alexander L. Shimkevich

In developing methods for designing reactor materials with reference to nuclear fuel, a task for micro-structural suppressing the processes of swelling, corrosion, and forming macroscopic defects (phase inclusions, pores, gaseous bubbles, cracks) in the fuel is formulated. For managing the defective structure of materials under irradiation, it is offered to choose their composition that fuel oxide ceramics have consisted of steady-state fractal tetrahedral clusters as the dense part of amorphous matrix (the nano-ceramic structure). In this connection, the search of multi-component systems providing this stable state can become a perspective direction for designing fuel with small swelling and corrosion factor. Such the materials will have high density of equilibrium vacancies that effectively absorb solid and gaseous fission products, and reduce the fuel swelling factor, physical, chemical, and thermal properties.

2021 ◽  
Vol 7 (4) ◽  
pp. 319-325
Author(s):  
Anastasiya V. Dragunova ◽  
Mikhail S. Morkin ◽  
Vladimir V. Perevezentsev

To timely detect failed fuel elements, a reactor plant should be equipped with a fuel cladding tightness monitoring system (FCTMS). In reactors using a heavy liquid-metal coolant (HLMC), the most efficient way to monitor the fuel cladding tightness is by detecting gaseous fission products (GFP). The article describes the basic principles of constructing a FCTMS in liquid-metal-cooled reactors based on the detection of fission products and delayed neutrons. It is noted that in a reactor plant using a HLMC the fuel cladding tightness is the most efficiently monitored by detecting GFPs. The authors analyze various aspects of the behavior of fission products in a liquid-metal-cooled reactor, such as the movement of GFPs in dissolved and bubble form along the circuit, the sorption of volatile FPs in the lead coolant (LC) and on the surfaces of structural elements, degassing of the GFPs dissolved in the LC, and filtration of cover gas from aerosol particles of different nature. In addition, a general description is given of the conditions for the transfer of GFPs in a LC environment of the reactor being developed. Finally, a mathematical model is presented that makes it possible to determine the calculated activity of reference radionuclides in each reactor unit at any time after the fuel element tightness failure. Based on this model, methods for monitoring the fuel cladding tightness by the gas activity in the gas volumes of the reactor plant will be proposed.


Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1060
Author(s):  
Hiroshi Hidaka

Isotopic analyses of elements in the natural reactor materials have often been performed to understand the distribution behaviors of the fission products and to evaluate the function of nuclear reactions since the first discovery of a natural reactor in 1972. Several types of unique microminerals, including significant amounts of fission products, have been found in and around the Oklo and the Bangombé natural reactors. In the past two decades, microbeam techniques using ion and laser probe facilities have been effectively applied for the in situ isotopic analyses of individual microminerals to investigate the migration behaviors of fissiogenic radioisotopes produced in the reactors. This paper presents a review of interpretations of the isotopic results of microminerals found in and around the natural reactors.


2012 ◽  
Vol 2 (4) ◽  
pp. 407-416 ◽  
Author(s):  
Hans Meinhardt

In his pioneering work, Alan Turing showed that de novo pattern formation is possible if two substances interact that differ in their diffusion range. Since then, we have shown that pattern formation is possible if, and only if, a self-enhancing reaction is coupled with an antagonistic process of longer range. Knowing this crucial condition has enabled us to include nonlinear interactions, which are required to design molecularly realistic interactions. Different reaction schemes and their relation to Turing's proposal are discussed and compared with more recent observations on the molecular–genetic level. The antagonistic reaction may be accomplished by an inhibitor that is produced in the activated region or by a depletion of a component that is used up during the self-enhancing reaction. The autocatalysis may be realized by an inhibition of an inhibition. Activating molecules can be processed into molecules that have an inhibiting function; patterning of the Wnt pathway is proposed to depend on such a mechanism. Three-component systems, as discussed in Turing's paper, are shown to play a major role in the generation of highly dynamic patterns that never reach a stable state.


1998 ◽  
Vol 233 (1-2) ◽  
pp. 281-284 ◽  
Author(s):  
C. Chung ◽  
C. Y. Chen ◽  
C. S. Lin ◽  
W. W. Yeh ◽  
C. J. Lee

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