Non-destructive assessment method for radiation damage of reactor pressure vessels in nuclear power plants

Abstract

The invention discloses a method for nondestructively evaluating the irradiation damage of a reactor pressure vessel in a nuclear power station. The method comprises the following steps: measuring the initial value of initial coercive force (HC) of a monitored part of reactor pressure vessel steel; measuring the coercive force HC of the same monitored part subjected to irradiation damage at any point in time; computing the coercive force change rate delta HC of the reactor pressure vessel steel during the process of irradiation damage according to the initial coercive force (HC) and the coercive force HC measured at any point in time, computing the real-time RTNDT, USE, Rm and Rp0.2 of the reactor pressure vessel during the process of irradiation damage, and performing analysis and evaluation on the irradiation damage degree of steel of the reactor pressure vessel steel. Compared with the prior art, the method has the advantages that the method is economical, environmental-friendly, safe and efficient, not only can perform real-time on-line evaluation, but also is accurate in data and good in testing operation safety, and can monitor the irradiation damage degrees of multiple parts of the reactor pressure vessel at the same time.

Description

Technical field [0001] The present invention belongs to the field of nuclear power technology. More specifically, the present invention relates to a method for non-destructively evaluating the radiation damage of a reactor pressure vessel in a nuclear power plant. Background technique [0002] The reactor pressure vessel is one of the most critical large-scale equipment in the nuclear island of a nuclear power plant. Its main function is to contain and support the steel pressure vessel of the core nuclear fuel assembly, control assembly, reactor internals and reactor coolant. It has been used for a long time in a strong radiation, high temperature, and high pressure environment. Among them, neutron radiation damage is one of its main failure modes. The specific manifestation is that the strength of the reactor pressure vessel steel increases, the toughness decreases, and the material hardens during the embrittlement process of the reactor pressure vessel steel. [0003] In order to...

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Problems solved by technology

[0008] (1) Due to the limitation of the internal space of the reactor pressure vessel, the number of loaded irradiation supervision tubes is very limited. Since the existing technology cannot realize the installation of radiation supervision tubes after a period of operation, it must be installed once before the first fuel loading operation. This method cannot fully meet the requirements for radiation supervision of reactor pressure vessels during the life extension of nuclear power plants in the future;

[0009] (2) At present, there are only two hot cell institutions in Sichuan and Beijing in China. After the radiation supervision tube is extracted from the reactor pressure vessel, it must be transported from the nuclear power plant to the designated hot cell institution over long distances across provinces. It has very high and strong radioactivity, so the security requirements during transportation are very high, the transportation cost is very high, and the cycle is long;

[0010] (3) Since the mechanical performance test of the irradiation supervision sample is a destructive test, a large amount of radioactive waste will be generated after the test is completed, and the subsequent treatment of the three wastes will be large and costly;

[0011] (4) Since the radiation monitoring samples come from the rest of forgings in the core area, this method can only monitor the damage degree of the reactor pressure vessel core area as a whole, and does not have the ability to monitor other parts of the reactor pressure vessel. , especially the degree of radiation damage at a specific location;

[0012] (5) It does not have the ability to monitor the radiation damage of reactor pressure vessel steel, and can only obtain the radiation damage degree of reactor pressure vessel steel at certain specific time points (depending on the extraction time of the radiation supervision tube)

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