The present disclosure relates to a method for monitoring failure of coated particles in fuel elements in a core of a
pebble-
bed high-temperature gas-cooled reactor, which is related to the technical field of
nuclear reactor engineering and includes the following steps: S11, calculating an inventory of a short-lived
noble gas fission nuclide; S12, obtaining a ratio of a release rate to a
birth rate of the short-lived
noble gas fission nuclide based on a temperature of the fuel elements using a Booth
diffusion and
release model; S13, deriving a theoretical expression 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, obtaining an experimental measurement value of the
activity concentration of the short-lived noble gas fission nuclide in the primary circuit at a sampling moment by gas sampling; S15, optimally calculating a failure fraction of the coated particles in the fuel elements and a share of
uranium contamination in the matrix
graphite in the core based on the theoretical expression and the experimental measurement value. The present disclosure can provide key parameters for the performance and status of the fuel elements in the core, which are required for
radiation safety studies, source term calculations and
accident analysis of the
pebble-
bed high-temperature gas-cooled reactor.