A substantial dynamic heat load of approximately 50 kW with 1800s periodic variation on a cryoplant is expected during Deuterium-Tritium (DT) operation for ITER Tokamak. To reduce the impact on cryoplant operation, the heat load mitigation technique has been proposed to suppress peak-to-peak heat load variation as utilizing the massive Toroidal Field (TF) coil structure (approximately 4000 tons) as a thermal buffer. Two heat load mitigation schemes are being under consideration; one is utilization of a bypass valve for Heat eXchanger (HX) to reduce the thermal energy dissipation at HX, the other is regulation of massflow rate in the cooling loop via cold circulator speeds to impose a time lag for the heat transfer rate at HX. Feasibility tests were successfully completed with the HElium Loop for hIgh lOad Smoothing (HELIOS) facility at CEAGrenoble under the frame work of ITER technical service contract. At the same time, the dynamic simulation model has been developed with a Cryogenic-Process REal time SimulaTor (C-PREST) at NIFS to validate the model against HELIOS data. C PREST has been utilized to model LHe plant which does not have modules to reproduce the thermo-hydraulic behavior of SHe cooling loop. Two unit modules, SHe process piping and SHe circulator, have been developed to implement HELIOS facility in C-PREST. The developed model demonstrated its robustness as reproducing the experimental results fairly well.