LOCA工况下环形燃料元件外包壳鼓胀爆破试验研究

为获得环形燃料元件外包壳在压水堆冷却剂丧失事故（LOCA）工况下鼓胀爆破温度和应变的经验关系式，为设计计算提供必要的输入，并初步评价其LOCA工况下的鼓胀爆破性能，在堆外对其开展了LOCA工况下的鼓胀爆破试验研究。在不同的升温速率和内压下，蒸汽环境中，以外表面红外加热的方式对环形燃料元件外包壳进行了鼓胀爆破试验。总结了试验得到的经验关系式，分析了试验中爆破温度和应变的影响因素，并将试验结果与美国核管理委员会出版的NUREG0630中的结果进行对比，验证了试验结果的合理性。获得的试验数据可用于环形燃料的设计、计算和改进。

Swelling and Rupture Experiment Study of Annular Fuel External Cladding under LOCA Condition

Annular fuel is a new type nuclear fuel for pressure water reactor (PWR). An annular fuel element has an external cladding corresponding to external coolant channel and an inner cladding corresponding to inner coolant channel, so the PWR of annular fuel has lower core temperature, less fission gas and higher safety allowance. As a new type nuclear fuel and prior to formally operation in the reactor, it’s necessary to test various performances of annular fuel under loss of coolant accident (LOCA) condition out of pile to ensure the safety of reactor core. In order to obtain the empirical relation of temperature and strain under swelling and rupture condition with LOCA of annular fuel external cladding, providing necessary input for design and calculation, and preliminarily evaluating its swelling and rupture performance, experiment of swelling and rupture of annular fuel external cladding was performed out of pile in China Institute of Atomic Energy. Under different heating rates and different internal pressures and in superheated steam atmosphere, which simulated the condition of LOCA in the actual reactor, the experiments were conducted through infrared heating outside cladding surface by infrared heating furnace. The result of single rod was analyzed and the empirical relations obtained from the entire results were summarized. The measurement error of temperature in the experiment was explained. The influencing factors such as heating rate, degree of oxidation and circumferential temperature difference of rupture temperature and strain under same internal pressure in the experiments were analyzed briefly. The experimental results were compared with NUREG0630 published by US Nuclear Regulatory Commission (NRC) in 1970s to verify the rationality. On the whole, the rupture temperature decreases with the increase of internal pressure and increases with the increase of heating rate, and the variation of rupture strain with rupture temperature is consistent with NUREG0630. The experimental results are in accord with the law, which is in good agreement with the results in NUREG0630. The data obtained from the experiment can be used in the design, calculation and improvement of annular fuel.