Numerical analysis on transient flow and temperature field during inlet flow blockage accidents of plate-type fuel assembly

Due to its superior performances such as compact structure, higher heat transfer efficiency, and deeper fuel burn-up, plate-type fuel assembly has been more and more widely utilized in new type integrated reactors arid experimental research reactors of which coolant is forced passing through the typical narrow rectangular channels formed by plate-type fuel in the core. Under some postulated accident conditions, such as irradiation damage, materials debris or foreign objects dragged into the core with the coolant circulation, and coolant flow assembly blockage accidents could occur. The accident may cause the reduction of coolant flow, make the fuel plate temperature increased, result in the phenomenon of dry-out, threaten the integrity of fuel cladding, and even cause the release of radioactive material into the reactor coolant system. The transient thermal-hydraulic characteristics of plate-type fuel assembly under inlet 95% partial and total flow blockage transient accidents are numerical simulated using the commercial CFD software ANSYS FLUENT 12.1 code. The liquid-solid conjugate heat transfer between coolant and fuel-plates has been considered in this calculation, and we analyzed the three-dimensional flow field, temperature field and the influencing factors. (authors)