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Method for calculating structure of molten pool in lower cap of pressure vessel in case of serious accident in reactor

A technology for pressure vessels and serious accidents, which is applied in the field of calculation of molten pool structure in the lower head of pressure vessels, can solve problems affecting reactor safety, accident mitigation technology effectiveness, etc., and achieve the effect of accurate evaluation

Active Publication Date: 2015-10-21
NUCLEAR POWER INSTITUTE OF CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the calculation of the molten pool structure involves the judgment of the effectiveness of the melt retention technology in the lower head of the nuclear reaction pressure vessel in a severe accident, if the molten pool structure cannot be accurately calculated, the actual effect of the severe accident mitigation technology may be caused, thereby affecting the safety of the reactor.

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  • Method for calculating structure of molten pool in lower cap of pressure vessel in case of serious accident in reactor

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Experimental program
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Effect test

Embodiment 1

[0055] In this calculation method, it is assumed that the core melt is liquid and there is no water in the core.

[0056] The calculation method for the molten pool structure in the lower head of the reactor severe accident pressure vessel includes the following steps when the molten material migrates to the lower head in the form of lateral migration:

[0057] step one: According to the calculation and generation file of the severe accident calculation program, when the upper surface of the melt is in contact with the lower surface of the lower support plate of the core, the program is used to calculate the components of the melt in the lower head of the pressure vessel (UO 2 , ZrO 2 , Zr and Fe) quality, enter step two:

[0058] Step two: Judging whether the melt composition is within the miscible range of the (U-Zr-O-Fe) system phase diagram according to the calculation results, if it is within the miscible range, the melt is uniformly distributed, if not, stratificatio...

Embodiment 2

[0086] Since the molten material migrates downward through the side of the head when the molten material migrates downward through the side of the pressure vessel, the level of the molten material in the lower head gradually rises and gradually approaches the lower support plate of the core. The surface, as the melt builds up, gradually floods the lower support plate and dissolves it. In this process, the change of the molten material is more complicated, especially the change of Fe content is very different. It is necessary to calculate and judge the molten material many times in the whole stage, so as to obtain the most accurate structure of the molten pool and accurately judge the next step. Risk of head failure.

[0087] And when the migration mode of the molten material is vertical migration, a large amount of molten material gathers on the core support plate, slowly melts and falls into the lower head together, although a small amount of molten material passed through th...

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Abstract

The invention discloses a method for calculating the structure of a molten pool in a lower cap of a pressure vessel in case of serious accident in a reactor. The method comprises steps of calculating masses of components of a reactor core melt in the lower cap, comparing the result of calculation with a mixing and dissolving scope in a component system phase diagram, determining whether the melt is layered depending on the result of comparison, and comparing the density of each melt layer to obtain the layered result of the melt if the melt is layered. Compared with a method that simply layer the structure of the molten pool, the method can calculate according to different migration modes of the reactor core melt, and fully consider the interaction among components during calculation, so the structure of the molten pool can be more accurately determined, so as to more accurately evaluate the validity of a delay measure in a melt pile in case of a serious accident in a reactor.

Description

technical field [0001] The invention relates to mitigation measures for severe accidents of nuclear power plants, in particular to a method for calculating the molten pool structure in the lower head of a pressure vessel under a severe accident state of a reactor. Background technique [0002] Some current nuclear power plants are designed to adopt the technology of retention of molten material in the lower head of the pressure vessel to alleviate severe accidents. Due to the stratification of the molten pool formed by the core molten material, the thermal focusing effect of the metal layer may be Cause the failure of the lower head of the pressure vessel. Therefore, for the retention technology of the melt pile, the analysis and judgment of the molten pool structure formed by the melt in the lower head of the pressure vessel have a great influence on the effectiveness of the technology. [0003] The melts contained in the molten pool are mainly metals and oxides. According ...

Claims

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Application Information

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IPC IPC(8): G06F19/00
Inventor 刘丽莉余红星邓坚陈彬武铃珺张明张航
Owner NUCLEAR POWER INSTITUTE OF CHINA