Study on Coupling Characteristics of Multiple Thermal Parameters during the Fuel Assembly Steady-State Irradiation in the Test Loop

The steady-state irradiation in the test loop is a key process to study the anti-irradiation performance of the fuel assembly. In view of the importance of the thermal parameters of the irradiation test loop to the test run, aiming at the steady-state irradiation in the test loop, combined with the requirements of fuel assemblies for the thermal parameters of the steady-state irradiation test, this paper analyzes the coupling characteristics of the key thermal parameters of the loop system under the changes of primary water flow and inlet temperature, the existence of heat exchange in the device and the operation mode of different heat exchangers. The research shows that with the decrease of the primary water inlet temperature and flow rate of the heat exchanger, the maximum heat exchange power of the main heat exchanger decreases significantly. Under the condition of serious deviation from the design condition, there is a risk that the heat exchange capacity of the main heat exchanger can not meet the irradiation operation of the fuel assembly. At the same time, the internal heat exchange of the irradiation device is extremely disadvantageous to the heat exchange of the main heat exchanger. Under the condition that the operating temperature of the loop is high and the internal heat exchange is strong, the design margin of the secondary water flow of the main heat exchanger shall not be lower than the heat exchange ratio in the device, and the margin shall be larger. The advantages of parallel operation of two main heat exchangers are mainly reflected in the large primary water flow, and there is a small primary water flow, which makes the heat exchange capacity of single heat exchanger running independently consistent with that of two heat exchangers running in parallel. When the flow ratio is lower than this, the heat exchange capacity of two heat exchangers running in parallel is weaker than that of single heat exchanger.