Method for equivalently simulating bending of fuel assembly in pressurized water reactor core

Abstract

The invention discloses a method for equivalent simulation of bending of fuel assemblies in a pressurized water reactor core, and the method comprises the steps: solving the width of a water gap between each fuel assembly in each axial layer after the fuel assembly is bent based on the width of the water gap when the pressurized water reactor fuel assembly is not bent and the bending size of the fuel assembly; based on an atom number conservation principle of water gap materials around the fuel assembly before and after bending, the water gap width before and after bending is kept unchanged, and an equivalent model of the fuel assembly after bending is established; and based on the established equivalent model after the fuel assembly is bent, carrying out transport calculation by adopting a transport calculation program which is the same as that when the assembly is not bent, so as to realize the influence analysis of the bending of the fuel assembly on the neutron-flux density. The method provided by the invention has the advantage of simple modeling, and can realize the rapid simulation analysis of the bending of the fuel assembly along with the time change by updating the nucleon density of the material on line. The method can be used for optimization design and analysis of the pressurized water reactor, the economical efficiency of the pressurized water reactor is improved, and the operation safety of a nuclear power station is enhanced.

Description

technical field [0001] The invention relates to the technical field of nuclear reactor core design, operation and safety, in particular to a method for equivalently simulating the bending of fuel assemblies in a pressurized water reactor core. Background technique [0002] In the long-term operation of the pressurized water reactor, the fuel assembly is in an environment under the combined action of its own thermal expansion, coolant flow, compaction force, irradiation burnup and other factors, the fuel assembly will bend, and the bending of the fuel assembly will The size of the water gap between the fuel assemblies is directly changed, which in turn changes the local neutron moderation of the core, thereby affecting the local power distribution of the core and affecting the safe and stable operation of the nuclear power plant. [0003] In order to accurately simulate the power distribution of the fuel assembly after bending, the Monte Carlo method is mainly used to describ...

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Problems solved by technology

[0002] Under the long-term operation condition of PWR, the fuel assembly is in the environment of the combined effects of thermal expansion, coolant flow, compaction force, radiation burn-up and other factors, the fuel assembly will bend, and the bending of the fuel assembly will be Directly change the width of the water gap between the fuel assemblies, thereby changing the local neutron moderation of the core, thereby affecting the local power distribution of the core, and affecting the safe and stable operation of the nuclear power plant

[0003] In order to accurately simulate the power distribution of the fuel assembly after bending, the Monte Carlo method is currently mainly used to describe the bending of the fuel assembly as realistically as possible through direct geometric modeling, and to analyze the influence of the bending of the fuel assembly on the power distribution of the fuel assembly. Establishing a geometric model is inefficient and difficult to deal with frequent changes in water gaps

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