The decay heat distribution calculation in molten salt reactor experiment based on the nuclide flow-transfer-burnup coupling method

The liquid-fueled molten salt reactor (MSR), unique among Generation IV systems, presents novel challenges due to its circulating fuel's multi-phase decay heat distribution. This study develops a nuclide flow-transfer-burnup coupling method to analyze spatiotemporal decay heat characteristics in MSRs. By analyze 8 MW Molten Salt Reactor Experiment (MSRE) primary loop, we find that, Short-lived nuclides (1s-1min half-life) contribute ∼40 % of equilibrium decay heat but rapidly decay when leaving the core, leading to flow-dependent spatial non-uniformity; While most decay heat (∼70 %) remains in salt, long-lived insoluble nuclides accumulate at high-surface-area components (e.g., heat exchangers); After reactor shutdown, salt-phase decay heat drops rapidly while wall-deposited nuclides maintain long-term heat output. Our framework enables accurate decay heat analysis under all operational conditions, revealing significant spatial heterogeneity both within and beyond the fuel salt (wall phase, gas phase, gas-remove systems). These findings are crucial for decay heat removal system design. Current uncertainties in bubble dynamics and mass transfer coefficients require further experimental validation.