Method for monitoring failure of coated particles in fuel elements in core of pebble-bed high-temperature gas-cooled reactor

A method for monitoring failure of coated particles in fuel elements in a core of a pebble-bed high-temperature gas-cooled reactor, comprising:

• S10, obtaining actual state information of a pebble-bed high-temperature gas-cooled reactor from the pebble-bed high-temperature gas-cooled reactor in operation;
• S11, determining an inventory Ii of a short-lived noble gas fission nuclide in a nuclear fission reactor based on the actual state information of the pebble-bed high-temperature gas-cooled reactor;
• S12, obtaining a ratio R/Bi of a release rate to a birth rate of the short-lived noble gas fission nuclide based on temperature information of the fuel elements in a core using a Booth diffusion and release model;
• S13, deriving a theoretical expression Ai(F,C) for an activity concentration of the short-lived noble gas fission nuclide in a primary circuit using a migration model of the nuclide in the primary circuit;
• S14, sampling gas at an inlet of a helium purification system in the primary circuit of the pebble-bed high-temperature gas-cooled reactor for a sampling time period, and measuring the gas to obtain an experimental measurement value ai of the activity concentration of the short-lived noble gas fission nuclide in the primary circuit at a sampling moment;
• S15, optimally calculating a failure fraction F of the coated particles in the fuel elements in the core and a share C of uranium contamination in a matrix graphite in the core using a least square method based on the theoretical expression Ai(F,C) for the activity concentration and the experimental measurement value ai;
• S16, maintaining a current operating state of the pebble-bed high-temperature gas-cooled reactor when the failure fraction F of the coated particles in the fuel elements in the core is less than a first preset value;
• adjusting operating parameters of the pebble-bed high-temperature gas-cooled reactor when the failure fraction F of the coated particles in the fuel elements in the core is larger than or equal to the first preset value and less than a second preset value, so that the failure fraction F of the coated particles in the fuel elements in the core is reduced to less than the first preset value;
• initiating a shutdown procedure of the pebble-bed high-temperature gas-cooled reactor when the failure fraction F of the coated particles in the fuel elements in the core is larger than or equal to the second preset value for more than a preset duration.