船用堆燃料棒包壳疲劳寿命分析

摘要

Background:The maneuverability of nuclear-powered ships requires the sharp step change of the output power of the marine reactor, which causes fluctuation of fuel cladding temperature and coolant pressure. Since the enormous fluctuation leads to fatigue damage of cladding, it is important to analyze the fatigue lifetime of the fuel claddings in marine reactor.Purpose:The purpose is to analyze the effects of cladding temperature, coolant pressure, internal pressure of fuel rod and irradiation on the fatigue lifetime.Methods:By using ANSYS, the thermal- mechanical behaviors of fuel rods in transient operation condition were simulated. The fatigue lifetime of cladding under different conditions was investigated, based on the design curves of the fatigue lifetime for zircaloy cladding. Results:The results indicate that the fatigue lifetime of the fuel cladding in marine reactor will reduce much in transient operation condition and irradiation can reduce fatigue lifetime of fuel cladding. The change of cladding temperature has little effect on the fatigue lifetime of cladding, compared with the change of coolant pressure. Conclusion:The fatigue damage in the fuel cladding in marine reactor is very serious. Suitable measures are suggested to take in order to reduce the fatigue damage of the cladding, under the premise of ensuring the maneuverability of ships.%船用堆瞬态变工况下燃料棒包壳温度和冷却剂压力波动较大,引起包壳的疲劳损伤,因此包壳疲劳寿命分析至关重要.本文利用ANSYS软件模拟船用堆瞬态变工况下燃料棒的热机械行为,结合锆包壳疲劳寿命设计曲线,考察包壳温度、冷却剂压力、燃料棒内压以及辐照对船用堆燃料棒包壳疲劳寿命的影响.计算结果表明,瞬态变工况使得包壳疲劳寿命有很大降低;包壳温度变化与冷却剂压力变化相比,前者对包壳疲劳寿命的影响小;辐照会降低包壳疲劳寿命.在不影响核动力船舶机动性的前提下,可采取一些必要的措施来降低包壳的疲劳损伤.