关键词: 路网脆弱性, 元胞传输理论, 烟羽应急计划区, 核应急撤离, 应急管理

Abstract: With the rapid development of the nuclear energy industry, the importance of emergency management of nuclear accidents is increasingly evident. As an important component of nuclear accident emergency management, emergency evacuation is an important measure to reduce residents’ radiation risk and protect residents’ life safety. According to the requirements for the emergency plan, once the nuclear power plant releases radioactive substances to the environment, residents living in the plume emergency plan zone will evacuate from the assembly place of residents, and the terminal point is the decontamination station at the boundary of the outer of the plume emergency plan zone. In the evacuation process, residents should try their best to avoid the roads covered by radioactive plumes, so as to complete evacuation rapidly and safely. If interference events (e.g., natural disasters, traffic accidents, road construction and so on) occur at the same time, resulting in the failure of some roads in the evacuation route, evacuees will be forced to detour and the evacuation time will be increased. More seriously, they may even force residents to pass the roads covered by smoke plume, increasing the risk of residents being exposed to radiation, and causing serious consequences to evacuation. In this study, this system characteristic of road network is called road network vulnerability. It can be found that the vulnerability of the road network in the plume emergency plan zone is an important factor restricting the evacuation of residents. Therefore, this paper researches the vulnerability of the road network in plume emergency plan zone, tries to find the key road sections which restrict residents’ evacuation, and carries out targeted management and repair measures. The research results can effectively mitigate the adverse impact of interference events on residents’ emergency evacuation, so as to ensure that residents’ nuclear emergency evacuation can proceed smoothly.
Considering that road interruption has a serious impact on evacuation time and evacuation risk of residents during nuclear emergency evacuation, a method to evaluate the vulnerability of road network in plume emergency planning zone during nuclear emergency evacuation is proposed. First, the risk time index is constructed to characterize the traffic performance of the road network in the plume emergency planning zone during nuclear emergency evacuation. Next, under the mode of “government organized evacuation+self evacuation under the guidance of the government”, bus drivers are trained strictly and tend to drive along the route arranged in advance. As a limited rational person, private car owners tend to choose their own satisfactory evacuation path according to the path length, evacuation risk and traffic jam degree. Therefore, a “private car road selection rule” is proposed to plan the evacuation route of private cars. Then, based on the cell transmission theory, considering the constraints of vehicle conflict at intersections, full load of buses and road choice of self-evacuating residents, a public evacuation model is built to minimize the risk time, which is used to solve the evacuation route and risk time of residents in any wind scenarios. Then, the invalid road is selected from the evacuation routes of residents in the given wind and deleted from the road network. The resident evacuation model is resolved to get the minimum risk time of resident evacuation. The next road is selected as the invalid road and the above calculation is carried out, until all the routes for residents to evacuate in the given wind are traversed. Finally, the next wind is given and the above calculation is carried out, until all the wind directions are traversed. With wind frequency as the weight, the differences of risk time between road interruption scenario and road network integrity scenario in all wind directions are weighted summed to calculate the road network vulnerability index value and find the key road.
Taking the plume emergency planning zone road network of T nuclear power plant as an example, the vulnerability index values of road network during nuclear emergency evacuation are calculated. The five roads with higher scores are selected as key roads. Through detailed analysis, it is found that the failure of the above roads can prolong the evacuation time of residents and increase the risk of radiation exposure to residents in the evacuation process under multiple wind direction scenarios. The results show that the proposed method can effectively assess the vulnerability of road network in plume emergency planning zone during nuclear emergency evacuation, identify the weak links of the network, and provide scientific basis for the maintenance and reconstruction of road network in plume emergency planning zone and nuclear emergency management.

Key words: road network vulnerability, cell transmission theory, plume emergency planning zone, nuclear emergency evacuation, emergency management