高温气冷堆在线燃耗测量系统的设计考虑--燃料球的冷却时间对燃耗测量的影响

利用堆芯总量程序包KORIGEN和蒙特卡罗程序MCNP4A软件分别模拟计算燃料球的燃耗和高纯锗(HPGe)探测器的响应,研究球床式高温气冷堆的燃料球在不同燃耗和不同冷却时间等测量条件下的燃耗测量不确定性问题。通过HPGeγ谱仪对燃烧过的燃料元件进行模拟!谱结果分析,如果用裂变核素137Cs作为燃耗测量的标示核素,要使燃耗测量系统的计数统计不确定度达到5%水平,燃料球的冷却时间不能低于6d,且燃耗测量时间至少需要15s。

Design Consideration of On-line Burnup Measurement System for High Temperature Gas-cooling Reactor: Influence of Cooling Time for Fuel Sphere on Burnup Measurement

Fuel spheres of the pebble bed high temperature gas-cooled reactor were non-destructively monitored on-line to ensure whether they reach their end-of-life burnup limit (80GWD/MTU).The core inventory Code (KORIGEN) and Monte-Carlo Code (MCNP4A) was used to simulate the burnup of fuel sphere and the response of HPGe detector, respectively. Uncertainty of burnup measurement was studied under different burnup values and cooling times. If indicator fissile nuclide of burnup measurement is 137Cs and counting statistical certainty of 5% for the bunrnup measurement system is met,the cooling time of the fuel shpere will be more than 6 d and the time of burnup measurement will be more than 15 s after the simulation results of the HPGe gamma-ray spectrometer for the irradiated fuel spheres are analyzed .