An Accurate Evaluation Method for Airborne Radioactive Source Items in Severe Accidents of Underground Nuclear Power Plants

Abstract

The invention discloses a method for accurately evaluating airborne radioactive source items in severe accidents of underground nuclear power plants, which comprises the steps of: 1) calculating core burnup for a specific underground nuclear power plant reactor; 2) determining radioactive activity according to an underground nuclear power plant burnup database Maximum burnup point; 3) Calculate the type and activity of radioactive substances released from the fuel into the pressure vessel; 4) Calculate the activity of radioactive substances released from the pressure vessel to the reactor building; The change of radioactive material activity over time; 6) Evaluate underground nuclear power plant cavern engineering measures and natural barriers, and calculate the activity of radioactive material entering the atmosphere; 7) Calculate the activity of radioactive material finally released into the environment. Combining the characteristics of underground nuclear power plants, the invention realizes the quantitative evaluation of the diffusion behavior of airborne radioactive source items when severe accidents occur in underground nuclear power plants through efficient and precise fuel consumption calculation theory and natural surrounding rock shielding calculation model.

Description

technical field [0001] The invention relates to nuclear power technology, in particular to a method for accurately evaluating airborne radioactive source items in severe accidents of underground nuclear power plants. Background technique [0002] The accident source term refers to the form, quantity, composition and time-varying release characteristics of radioactive substances released into the environment by a nuclear power plant when an accident occurs. Accident source items are the basis of accident management and emergency planning of nuclear power plants, and are divided into design basis accident source items and severe accidents. Severe accident source term is an important input of accident consequence evaluation. After the Fukushima nuclear accident, severe accident source term evaluation has been widely concerned and valued. Estimating airborne radioactive source items in severe accidents and calculating the radiation consequences inside and outside the accident s...

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Problems solved by technology

However, these accident source items are all calculated on the basis of a specific reactor, which are general source items and cannot be accurately calculated for specific reactors.

After the Fukushima nuclear accident in Japan, a large number of studies on the source term of severe accidents have been carried out at home and abroad, but none of them have clearly proposed the combination with precise and efficient fuel consumption calculation methods.

At the same time, underground nuclear power plants have a thicker natural surrounding rock shielding layer outside the plant, which can effectively block the migration of airborne radioactive substances. Evaluation theory of surrounding rock shielding layer, a new calculation method is proposed

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