CAJ | 학술논문

根据现有的设计资料,使用一体化严重事故分析程序 MELCOR1.8.6建立了核电厂一、二回路系统,非能动堆芯冷却系统和安全壳系统的模型,并模拟冷段2英寸(5.08 cm)小破口叠加重力注入失效的严重事故发生后,将冷却剂注入堆芯的情形,分析其对严重事故进程的缓解能力。本文选取3个严重事故的不同阶段,将冷却剂分别以小流量(10 kg/s)、中流量(50 kg/s)和大流量(200 kg/s)的速率注入堆芯,通过比较氢气产生量、堆芯放射性产生量及堆芯温度等数据来评估在严重事故不同阶段再注水的可行性。结果表明：在堆芯损伤初期,可认为10 kg/s以上的流量足以冷却百万千瓦级事故安全。而当严重事故发展到堆芯开始坍塌阶段,200 kg/s的注水流量可认为是基本可行的,而小于此流量的注水应慎重考虑。
근거현유적설계자료,사용일체화엄중사고분석정서 MELCOR1.8.6건립료핵전엄일、이회로계통,비능동퇴심냉각계통화안전각계통적모형,병모의랭단2영촌(5.08 cm)소파구첩가중력주입실효적엄중사고발생후,장냉각제주입퇴심적정형,분석기대엄중사고진정적완해능력。본문선취3개엄중사고적불동계단,장냉각제분별이소류량(10 kg/s)、중류량(50 kg/s)화대류량(200 kg/s)적속솔주입퇴심,통과비교경기산생량、퇴심방사성산생량급퇴심온도등수거래평고재엄중사고불동계단재주수적가행성。결과표명：재퇴심손상초기,가인위10 kg/s이상적류량족이냉각백만천와급사고안전。이당엄중사고발전도퇴심개시담탑계단,200 kg/s적주수류량가인위시기본가행적,이소우차류량적주수응신중고필。
The MELCOR1.8.6 code was applied to a severe accident model of a 1 000 MWe PWR which includes primary system,secondary system,passive core cool-ing system and containment system.For the transient case,a small break LOCA with 2 inch (5.08 cm)break at the cold leg concurrent with failure of gravity injection was selected.After the core was damaged due to the failure of gravity inj ection,it was assumed that the coolant was inj ected into the pressure vessel,and then the water reflooding effectiveness was evaluated and analyzed.In this calculation,the coolant injection into reactor core with the small (10 kg/s),medium (50 kg/s)and large (200 kg/s)mass flow rates respectively at 3 different time stages of the severe accident was simulated.The effectiveness of water reflooding was assessed through hydrogen production,radioactive materials released from core,and core temperature.The results show that the mass flow rate above 10 kg/s is believed to be efficient for cooling a 1 000 MWe reactor at the beginning of core damage.However,with the accident devel-oping to core relocation,a large mass flow rate of 200 kg/s is considered to be applicable for core cooling.As a result,the mass flow rate below this value should be carefully considered when inj ecting water into the core.