压水堆嬗变长寿命裂变产物的弹棒事故安全性研究

Study of Rod Ejection Accident Safety of PWR for Long-lived Fission Product Transmutation

为分析压水堆(PWR)嬗变长寿命裂变产物(LLFP)的堆芯瞬态安全性,基于CASMO-4、RSIM以及改进的NLSANMT/COBRA-4程序搭建了程序系统,并利用该系统研究了嬗变堆芯在弹棒事故下的安全特性,分析了寿期初和寿期末事故发生后的功率变化及燃料中心温度变化。数值结果表明:与参考PWR相比,装载99 Tc将会使温度系数变得更负,因此弹棒事故下峰值功率降低,而装载129I则相反;装载这两种裂变产物时,燃料中心温度最高可升高127~157℃,仍距UO2芯块熔化限值温度有较大裕量。

In order to carry out transient safety analysis of PWR cores used for long- lived fission product （LLFP） transmutation, a code system was developed based on CASMO-4, RSIM and modified NLSANMT/COBRA-4. Using this system, the safety feature of LLFP transmuting PWR in rod ejection accidents was studied and the power evolution and maximum fuel center temperature variation were analyzed at both BOL and EOL. The numerical results show that loading 99Tc leads to lower peaking power because of more negative moderator temperature coefficient, while loading 129I results in higher peaking power. Also, loading 99 Te and 129I will make fuel center temperature rise up about 127-157 ℃, which is still within the melting point of UO2 fuel.