Method for analyzing core transient of pressurized water reactor through Pin-by-Pin

Abstract

The invention discloses a method for analyzing a core transient of a pressurized water reactor through Pin-by-Pin. The method comprises the following steps: 1, calculating an initial state of the core to serve as an initial point of transient analysis; 2, considering external disturbance for the next time step, and updating the section by utilizing neutron-flux density of the last time step so as to obtain a coefficient and a source item of an SP3 steady-state equation; 3, expanding the SP3 steady-state equation at the (tn+1)th step subjected to Pin-by-Pin numerical solution time discretization in a nodal time space by utilizing an exponential function, and performing iterative solution convergence to obtain zero-order and second-order neutron-flux density of lattice cells under a new time step; 4, updating delayed neutron precursor concentration; 5, judging whether the current time step is the final time step, if not, repeating 2-4, and if so, stopping calculation, and outputting transient parameters. Compared with an assembly homogenization method, the method disclosed by the invention has the advantages that an error introduced by power reconstruction does not need to be considered; compared with diffusion approximation, only the zero-order neutron-flux density can be obtained, and more reactor core information is remained. Meanwhile, the solution time is not obviously increased.

Description

technical field [0001] The invention relates to the fields of nuclear reactor design and reactor physical calculation, in particular to a Pin-by-Pin method for analyzing the transient state of a pressurized water reactor. Background technique [0002] During the operation of the reactor, it is necessary to control the real situation in the reactor in real time, so that the operator can adjust the reactivity in time, avoid the occurrence of the accident, or control the scope and level of the accident after the accident, and ensure the safety of the staff and the surrounding people. Safety of life and property. This requires the research of a real-time and accurate method for analyzing the transient process of the PWR core, that is, neutron dynamics calculation. There are many kinds of core event-related phenomena, which can be roughly divided into three categories according to the different process time constants: short-time transient, medium-time transient and long-term tra...

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Problems solved by technology

[0003] It is very time-consuming to directly solve the neutron transport equation with the deterministic method, which cannot meet the real-time requirements. Therefore, the traditional method is to solve the neutron diffusion equation approximated by the angle P1. In space, the idea of ​​component homogenization is usually adopted, and the first solution is to obtain The neutron flux density of the components is homogenized, and then the power distribution inside the components is obtained through power reconstruction

However, the neutron flux density and power distribution obtained in this way often have large errors with the actual real results, especially for local non-uniform effects

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