高燃耗下UN-FeCrAl燃料元件稳态及瞬态热力学性能分析

UN-FeCrAl燃料元件作为耐事故燃料高燃耗应用的主要方案之一，需要评价其在高燃耗下的热力学性能。本研究基于FUPAC软件对UN-FeCrAl燃料元件在燃耗68000 MW·d·t?1(U)下的稳态和瞬态热力学性能进行了预测。分析结果表明，稳态工况下UN-FeCrAl燃料元件热力学性能表现良好；瞬态下UN燃料的芯块中心温度最高仅为862℃，可满足芯块温度设计要求，但FeCrAl包壳的瞬态应力最大将达到459 MPa，且瞬态应变量相比于稳态应变量最大增加了0.23%，这可能会使FeCrAl包壳面临瞬态应力和瞬态应变准则超限的风险。因此后续研究应重点关注FeCrAl包壳的瞬态应力和瞬态应变性能。 

Steady and Transient Thermodynamic Performance Analysis of UN-FeCrAl Fuel Element under High Burnup

The UN-FeCrAl fuel element is one of the main schemes for high burnup application of accident tolerant fuel, and the thermodynamic property of the fuel element under high burnup needs to be evaluated. The steady and transient thermodynamic property of UN-FeCrAl fuel element under 68000 MW·d·t?1(U) was predicted by FUPAC software, and the analysis results showed there is a good thermodynamic property of UN-FeCrAl fuel element under steady condition. Under transient conditions, the maximum pellet center temperature of UN fuel is only 862℃, which can meet the requirements of pellet temperature design, but the maximum transient stress of FeCrAl cladding will reach 459 MPa, and the transient strain will increase by 0.23% compared with steady-state strain, which may make FeCrAl cladding face the risk of transient stress and transient strain criterion exceeding the limit. Therefore, the subsequent research shall focus on the transient stress and transient strain of FeCrAl cladding.