Polynomial maximum likelihood estimation-based soft measurement method for temperature field of reactor core of nuclear power plant

Abstract

The invention discloses a polynomial maximum likelihood estimation-based soft measurement method for a temperature field of a reactor core of a nuclear power plant. The method comprises the steps of firstly performing primary reconstruction on a two-dimensional temperature field of the cross section of a reactor core coolant outlet of a pressurized water reactor by taking a temperature measurement point of the reactor core coolant outlet as discrete data through utilizing a maximum likelihood estimation polynomial fitting method; secondly building a reactor core temperature calculation model and a reactor core heat conduction model; thirdly calling coolant thermal parameters and performing calculation by utilizing a heat exchange formula to obtain flow of each coolant channel; and finally, performing forward-reasoning / reverse-reasoning calculation of a temperature value of a next segment by utilizing an iterative method through taking an inlet / outlet cross section temperature as a known condition, so that soft measurement of coolant three-dimensional temperature distribution of the whole reactor core is finally realized. The method has the beneficial effects that the cross section temperature measured by a sensor which cannot be arranged in the reactor core is obtained through the calculation model by utilizing an existing temperature single point measurement value of the reactor core coolant outlet, and further guarantee is provided for safe running of the nuclear power plant.

Description

technical field [0001] The invention belongs to the technical field of thermal measurement, in particular to a soft measurement method for nuclear power plant core temperature field based on polynomial maximum likelihood estimation. Background technique [0002] With the development of my country's economy, the demand for power supply is increasing, and non-fossil energy is gradually replacing the role of fossil energy by virtue of its clean and renewable advantages. Relying on its advantages in resources, environment and economy, nuclear energy has gradually become the new darling of the energy industry. With the development of nuclear energy, people pay more and more attention to nuclear safety issues, and the requirements for effective control and safety control of nuclear power plants are getting higher and higher. [0003] In a pressurized water reactor nuclear power plant, the coolant in the primary circuit leads the heat released by the nuclear fuel assembly out of t...

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Problems solved by technology

When the core temperature exceeds the limit value, melting will occur, resulting in nuclear leakage; although there will be no serious nuclear safety accident if the temperature is not large, it will cause thermal damage to the cladding material of the fuel element, resulting in life loss, and accumulated multiple times It is still possible to cause a serious nuclear accident

[0004] Due to the limited number of setting points in the existing "point" temperature measurement, there is a monitoring blind area, and the core temperature distribution cannot be observed globally

Moreover, even if the temperature measuring points are arranged according to the design parameters such as the hot aisle, in actual operation, with the change of fuel consumption, xenon oscillation, control rod position, etc., the hot aisle and the hot spot will drift, so the arranged temperature cannot be guaranteed. The measuring point can monitor the highest temperature inside the core all the time

At present, there are no records on the research on the soft measurement of the core temperature field in nuclear power plants

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