Experimental device and method for measuring hard shell thickness and growth rate of melt

Abstract

The invention discloses an experimental device and an experimental method for measuring a hard shell thickness and a growth rate of melt. The experimental device is a multipoint thermocouple measuring device designed based on an experiment bench of a 1 / 4 circle two-dimensional slicing structure according to a ratio of 1:1 of a lower seal head of an ACP1000 reactor pressure vessel. The hard shell thickness of the melt is indirectly obtained by utilizing the temperature measured by a multipoint thermocouple; since an obvious temperature difference exists on a phase interface, a temperature reached by the front edge of the hard shell at a certain moment can be obtained according to step change of the temperature of each measuring point; the multipoint thermocouple is arranged at different positions of the wall surface of the pressure vessel on an experimental section, so that the hard shell thickness of the melt at different positions can be measured; the data of the multipoint thermocouple is recorded in the whole experimental section process by utilizing a data acquisition system in the experimental process, transient characteristics of the hard shell thickness of the melt along with time change can be obtained, and the growth rate of the hard shell of the melt can be obtained by analyzing the hard shell thickness at different moments; and the invention provides an important measuring method for a research experiment of nuclear reactor disaster safety.

Description

technical field [0001] The invention relates to the technical field of research on heat transfer characteristics of a head melting pool under a severe accident in a nuclear power plant, in particular to an experimental device and method for measuring the thickness and growth rate of a hard shell of a melt. Background technique [0002] When a serious accident occurs in a pressurized water reactor in a nuclear power plant, if the core cannot be effectively cooled, the core will melt, and the high-temperature core melt may fall into the lower head of the pressure vessel and form in the lower head of the pressure vessel. Melting pool structure; under the action of the decay heat of the core melt, the high-temperature melting pool transfers heat to the wall of the lower head of the pressure vessel, resulting in an increase in the temperature of the wall of the lower head of the pressure vessel, which seriously threatens the integrity of the pressure vessel; if the pressure If th...

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Problems solved by technology

[0004] At present, the experimental research carried out is almost all steady-state experiments, mainly studying the heat transfer characteristics of the molten pool under long-term cooling conditions, and the working fluid and experimental conditions selected in most experiments cannot reflect the heat transfer of the molten pool during the solidification phase transition process. The influence of the characteristics, there are few studies on the transient heat transfer process and the phase transition characteristics of the solidification of the melt before the molten pool is formed and reaches a steady state;

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