Dynamics of temperature fields during Wigner energy release in bulk graphite irradiated at low temperature

• Published in: Journal of nuclear materials 2019-03, Vol.515, p.303-311
• Main Authors: Pavliuk, A.O., Kotlyarevsky, S.G., Bespala, E.V., Novoselov, I. Yu
• Format: Article
• Language: English
• Subjects: Adiabatic; Adiabatic conditions; Air temperature; Containers; Decommissioning; Energy; Graphite; Heat; Heat effects; Heat transfer; High temperature effects; Internal energy; Irradiation; Low temperature; Parameters; Radioactive waste disposal; Radioactive wastes; Temperature effects; Uranium; Uranium-graphite reactor; Waste disposal; Wigner energy
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2018.12.044

This paper is concerned with determination of parameters associated with release of the energy accumulated in irradiated graphite. These parameters define the conditions and possible consequences of the release – the heat effects, both in the course of the all types of uranium-graphite reactors (UGR) decommissioning work and during the entire irradiate graphite management process, including treatment, storage, and disposal of the graphite radioactive waste (GRW). Results of analysis of the magnitude and dynamics of maximum possible heat effects because of Wigner energy release in the graphite stack and in the volume of graphite parts loaded into large containers were presented. Results of modeling showed the most critical conditions from the standpoint of the potential heat effect values because of Wigner energy release in large volumes of the graphite irradiated at low temperature. Those conditions were achieved when the temperature of the entire graphite volume reached the temperature of self-induced stored energy release (the initiation temperature). In the case, the energy was released within the entire volume simultaneously. This path of accumulated energy release was characterized by the high annealing intensity, and under the heat transfer conditions with the air environment the temperature of graphite could reach the values inherent to adiabatic conditions, ∼800oС. •.A process of Winger energy release in graphite bricks and sleeves is shown.•.Results of modeling of potential heat effect values because of Wigner energy release in irradiated graphite are demonstrated.•.The dependence between measurements of irradiated graphite and peak temperature under Wigner energy release is detected.