Explosion-resistance of the cylindrical part of a fast-reactor vessel

Abstract

As one of the safety barriers, the main vessel of a fast reactor must be strong enough to prevent radionuclides from entering the environment during any type of accident, including hypothetical accidents. The most serious accident is an impulsive release of energy with melting of the fuel and boiling of the coolant (liquid sodium). The rate of emission of the boiling sodium from the core determines the growth of excess reactivity, i.e., the rate of energy release in an accident. Some of the energy is transferred through the sodium and the intrareactor equipment to the vessel, which in the process is subjected to dynamical loads, predominantly impulsive loads which are characteristic of explosions. Therefore, one of the most important characteristics of the strength of a vessel is its explosion-resistance.The need for engineering methods of guaranteeing nuclear power plant safety has made it necessary to study experimentally the vessel strength and to develop methodological principles for analyzing it numerically. The All-Russia ScientificResearch Institute of Electrophysical Apparatus (Arzamas-16) and the Special Office of Machine Design (Nizhnii Novgorod) have performed investigations which have made it possible to assess the static strength and explosion-resistance of the vessel of an operating BN-600 reactor and at the design stage of future reactors, and the possible consequences of impulsive loading of the reactors in a hypothetical accident. The experimental part of the investigations was directed toward the solution of several problems.1. Study of the scale effect [i] accompanying the explosive destruction of models or prototypes of the vessel. This is necessary in order to determine the validity of transferring the results of model experiments to a full-scale vessel, since it is impossible to experiment with a full-scale vessel in this manner.2, Study of the properties of chromium-nickel steel (the main material used in fast-reactor vessels) with rapid deformation, characteristic of accidents. It is well known that under a dynamical load the characteristics of steel differ substantially from the static characteristics.3. Study of the effect of the characteristics of an internal impulsive load on the behavior of the reactor vessel: character and rate of impulsive energy release (for correct simulation of energy release in an accident); degree of filling of the vessel with liquid coolant or its analog (for example, water in the case of reactors with liquid sodium); displacement of the focus of impulsive energy release from the center of the core (this degrades the explosionresistance of the vessel); and, intrareactor equipment, which strongly influences the parameters of an impulsive load on the vessel. 4. Study of the explosion-resistance of models of a vessel with detonation of high explosives in the models. 5. Estimation of the explosion-resistance of a full-scale vessel and its carrying capacity under the conditions of offdesign accidents.6. Mathematical analysis of the experiment and comparison of the ...

Dynamic responses of discrete multi-layered explosion containment vessels with the consideration of strain-hardening and strain-rate effects

“…Furthermore, Refs. [4][5][6][7][8] deduced a relationship with the planestrain ring theory between the explosion weight and the maximum plastic deformation. For air-filled ECVs, by using the plane-strain ring theory, Duffey [9,10] obtained the final radial displacement in the explosion section and the displacement along the axial direction, which were both in good agreement with experimental results.…”

Investigation of the rate dependences of the stress of plastic flow and fracture of Mn2-Si steel at normal and elevated temperatures

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