Simulation method for efficiently solving unsteady heat conduction problem of reactor core fuel rod

Abstract

The invention discloses a simulation method for efficiently solving an unsteady heat conduction problem of a reactor core fuel rod. The method comprises the following steps of (1) carrying out reasonable simplification on an actual fuel rod model, building a geometrical model and carrying out discrete numbering on the model; (2) changing an original second-order partial differential equation into two first-order partial differential equation sets by using an order reduction method; (3) building a relation of physical quantities, about the physical quantities of an initial point, of any point on a mathematic model; (4) solving unknown quantities in the relation by using known boundary conditions; and (5) solving temperature parameters of required positions at different moments. A highest-order matrix is always kept in two-dimension in a calculation process no matter that the geometrical model is transformed, so that the occupied computer resource is small, and the simulation method can be used for quickly and accurately predicting the temperature parameters of the model, and is particularly very effective for solving the heat conduction problem with fast changes in boundary conditions.

Description

Technical field [0001] The invention belongs to the field of temperature measurement and control of nuclear power plants, and particularly relates to a simulation method for efficiently solving the problem of unsteady heat conduction of a core fuel rod. Background technique [0002] The core fuel rods of nuclear power plants are the hottest part of the reactor. Therefore, in order to avoid core meltdown, it is necessary to keep track of the temperature of each position of the fuel rods and control the reactivity of the core to keep the temperature of the fuel rods within a reasonable range. [0003] In order to obtain the temperature of the fuel rods in the core, we insert a temperature detector at the required position. However, the number of detectors is very limited, and in order to avoid damage to the temperature detectors, the temperature detectors are mostly placed at the two ends of the core fuel rods at a lower temperature. Although the temperature parameters obtained by t...

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Problems solved by technology

[0006] (1) Only a few discrete temperature points can be obtained by simply using the temperature detector, and the overall temperature distribution on the fuel rod cannot be obtained;

[0007] (2) The finite volume method has a good application in solving the temperature field, but it adopts the method of regional discretization. The unknown quantity involves the whole domain, so the established matrix is ​​large, the required calculation time is long, and the calculation efficiency is not high.

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