Safe evacuation routing due to emergency scenarios in Rooppur nuclear power plant during a beyond design-basis accident

Abstract

In this study, emergency evacuation routing for Rooppur Nuclear Power Plant (RNPP) was studied by combined analysis using Personal Computer Transient Analyzer (PCTran) simulator and ArcGIS software. PCTran VVER 1200 and PCTran RadPuff simulators were used for analysis of two hypothetical accident scenarios at RNPP, one in which LBLOCA was followed by SCRAM and another one in which SCRAM has not been initiated. Station blackout was considered in both cases so that only the passive safety systems were functional. A break size of 1000cm2 in the hot leg of reactor was considered to simulate an extreme accident condition for both scenarios. Transient response and integrated radioactivity release data were generated by PCTran VVER 1200 for both of the two accident scenarios. Then dispersion of the released radioactivity was analyzed by PCTran RadPuff simulator including plume trajectory for four different seasons. Seasonal variation of meteorological conditions such as wind speed, wind direction and stability for RNPP were taken into consideration. Three evacuation zones of 2-mile, 5-mile and 10-mile radius were considered as the plume exposure boundary as per the United States Nuclear Regulatory Commission (USNRC) recommendation. Additional 30-mile plume ingestion pathway boundary was included for emergency facility response and evacuation routing. Emergency facilities within this 10-mile and 30-mile boundaries were identified by Google Earth Pro software. Road network around the RNPP inside a 30-mile boundary was generated in ArcGIS. The network analyst tool of ArcGIS was used to solve the road network for different emergency-response facilities applying classical Dijkstra’s algorithm. Finally, evacuation routing from RNPP to hospitals outside 10-mile plume exposure boundary was developed for emergency transport and treatment of radiation exposed personnel. In this study, it was found that Kr-88 and Xe-133 contributed mostly to the integrated activity release compared to other isotopes. For the second accident scenario, a greater percentage of iodine isotopes made thyroid dose rates higher than TEDE dose rates. In the present work, a total of 22 fire stations, 53 police stations, 24 hospitals and 25 community clinics were identified within the study area. Shortest evacuation routes for each facility location were determined for the fastest emergency response. Evacuation map was established for 17 hospitals outside 10-mile boundary. Moreover, suitability classification of every hospital was done according to the seasonal plume trajectory directions from dispersion analysis.