| In the magnetic confinement fusion reactor,blanket is a key component to achieve the energy conversion and tritium self sufficiency.To effectively enhance the tritium breeding ratio and the energy amplication coefficient,the High Tritum Breeding Ratio Blanket(refeers to HTBB)which adopts natural uranium as the neutron multiplier has been proposed.This promising blanket can reduce the loss of tritium at the same nuclear power,and reduces the requirement of irradiation resistance of structural materials.At the same time,the introduction of fisson material lead to the safety problem of decay heat.To ensure the blanket can meet the design requirement under various operating conditions and typical accident conditions,it’s necessary to conduct thermal-hydraulic safety analysis.Based on the structure-physics design of the blanket,the system code RELAP5/Mod 3.4 and the computational fluid dynamics code FLUENT are utilized to compute and analyze the safety characteristics of HTBB in the total blankets scale,and the details are as follow.Above all,considering there are plenty of pipes,complicated flow,and heat transfer structures in the HTBB,the model method of the fuel zone in a single blanket is discussed,then two different methods are proposed,and the modeling of first wall-tritium breeding zone is completed.To achieve the heat conduction between the fuel zone and the first wall,the heat structures are modified,and an equivalent heat conduction coefficient is computed to stay the heat transfer same.After the single blanket has been modeled,an intact reactor has been built.The calculation results of steady-state show the good agreement with the design values.Then the transient calculation of loss of all coolant flow flux of the fuel zone,loss of off-site power of the fuel zone and loss all electrical power supply with pump rotor lock of the fuel zone are carried out.The results of loss of all coolant flow flux of the fuel zone show that after the main pumps fail to run,the flow flux of coolant begin to reduce,and the residual heat is removed by the steam generator and the first wall-tritium breeding zone cooling system.The first wall-tritium cooling system could remove more heat in the early period.The results of loss of off-site power of the fuel zone show,the first wall-tritium breeding zone cooling system could take the all residual heat away.After two actions of the safety valve,the pressure decreases,and the blanket is always under the safety conditions.To deal with the beyond design basis accident,the Passive Residual Heat Removal system is recruited to the reactor system.The results of the loss of off-site power of the fuel zone and loss all electrical power supply with pump rotor lock of the fuel zone accident show,with the two cooling systems and the PRHRS,the reactor has enough capability to resist this accident.Because the RELAP5 code couldn’t implement the heat conduction between two heat structures,the model is not suitable for the loss of coolant accident.To simulate the LOCA,a three-dimensions blanket model is built,and assume the fuel zone loss of all coolant,then acquire the distribution of temperature under the different residual heat level.The results imply that the first wall-tritium breeding zone cooling system could remove 8.58%relative power.Moreover,we calculate the LOCA,which the break located at the cold leg,and analyze the influences of different break area. |
