严重事故堆芯熔融物μ子成像监测系统及重建算法研究

Following the Three Mile Island and Chernobyl accidents, Fukushima in 2011 alerts people once again not to ignore the low-probability severe core debris accident. When a severe accident happens, the status of the core debris is particularly important for tracking accident progression and determining the emergency plan. However, under the ultra-high temperature, strong radiation, corrosion and other harsh conditions along with core melting, there is no conventional technique which can be used to accurately monitor the core status. Cosmic ray muon imaging technique is sensitive to high atomic number materials with high penetration, which has been demonstrated applicable to the monitoring of nuclear materials. This project will focus on imaging monitoring system and reconstruction algorithm for core debris in severe accident. Firstly, a monitoring system based on cosmic ray muon imaging technique will be put forward. Secondly, a system model for nuclear island including the core debris will be developed. And then, muon transport processes will be studied and simulated for generating projection data with the Monte Carlo method. Finally, a new muon imaging reconstruction algorithm with faster reconstruction speed and better reconstruction quality for incomplete data will be proposed. The final reconstructions will help personnel keep abreast of accurate accident progression. This project is ground-breaking in monitoring of core debris under severe accident conditions, and it will do some foundation work for the leading position of our country in this field.

继三里岛和切尔诺贝利事故后，2011年福岛核事故的发生再一次警醒人们不能忽视小概率堆芯融化的严重事故。当发生严重事故时，堆芯熔融物的状态对于跟踪事故进程，进而确定应急方案显得尤为重要。但是，在堆芯融化时超高温、强辐射、强腐蚀等恶劣条件下，目前没有任何一种传统技术能够对堆芯状态进行准确的监测。宇宙射线μ子成像监测技术具有高穿透力、对高原子序数物质敏感等特点，已被证明适用于核材料的监测。本项目将对严重事故堆芯熔融物监测系统及成像算法进行研究。提出一种基于宇宙射线μ子成像技术的监测系统，建立包括堆芯熔融物在内的核岛系统模型，研究μ子输运过程并使用蒙特卡罗方法产生模拟投影数据，然后提出一种新型快速、准确的不完备数据μ子成像算法，最终重建结果适用于应急指挥人员及时了解准确的事故进程。本项目的开展，对严重事故工况下堆芯熔融物监测的研究具有开拓意义，也将为我国在该领域的领先地位奠定基础。

本项目通过广泛调研，建立了严重事故堆芯熔融物μ子成像监测系统及模型；利用蒙特卡罗方法模拟完成了μ子输运过程，并提出了一种适用于μ子图像重建的不完备数据算法；最后提出了一种适用于核事故应急人员及时了解堆芯损伤事故进程的方法，并在此基础上，提出了一种适用于我国目前运行及在建核电厂的快速堆芯损伤评价方法，为我国核事故应急堆芯损伤快速评价系统顶层设计的最终制定提供有利依据。. 本项目共计发表论文11篇，其中EI检索4篇、核心期刊4篇、国际会议论文2篇、国内会议论文1篇；授权3项实用新型专利；培养1名硕士研究生，2名高级工程师，1名工程师。