Study On Critical Cracking Heat Transfer Of Z - Pinch - Driven Fusion Fission Mixture

Fusion-fission hybrid reactor, colligating the fusion and fission technology, is an important way for nuclear energy to realize the sustainable development. Z-FFR uses the stable pulsing burning device, Z-Pinch, as the fusion neutron source which drives the water cooling subcritical blanket. The energy release of subcritical blanket has obvious pulse characteristics that means it happens in a very short time and the pulse power is extremely high. The pulse may induces non-Fourier heat conduction effect resulting in heat transfer deterioration, so the program to evaluate the security features of subcritical blanket must include the non-Fourier heat conduction model.Based on this background, the paper completes the heat transfer analysis of the Z-FFR subcritical blanket, mainly consisting of the following work.(1) We deduce the non-Fourier heat conduction governing equation with internal heat source, and discus the difference with classical heat transfer theory. The mathematic model for subcritical blanket heat transfer analysis is established. With the model, we solves the heat transfer problem of a one-dimensional infinite plate.(2) The calculation program including non-Fourier heat conduction model is developed with finite volume method, and it use second-order upwind difference scheme and dual-time stepping method to solve the unsteady problem. Calculation examples demonstrate the reliability of the program.(3) On the base of concluding the subcritical blanket’s energy source features and clearing the blanket structure, we do the transient heat transfer analysis of the subcritical blanket. The time for establishing stable periodic changes in each area is got, also the radial position and formation time of the hot point. The changing processes of the fuel region and first wall temperature field is showed. According to the thermal result of the two dimension radial model and the law of energy conservation, we work out the mean coolant temperature of the outlet and get the DNBR with W-3 formula to verify the security characteristics of the subcritical blanket. For the coolant pipe block accident, the subcritical blanket is safety with pipe block rate up to 8.3%. Finally, the influence of relaxation time to the blanket thermal field is discussed that the contribution of heat source fluctuation is amplified with huge relaxation time.