Comparative radiological impact of LOCA and RDD scenarios: An AI-enhanced assessment using HotSpot code

Abstract

This study provides a comprehensive radiological assessment of two hypothetical incidents: a Loss of Coolant Accident (LOCA) at a nuclear reactor and a Radiological Dispersal Device (RDD) detonation, both simulated in Dhamar City, Yemen, using the HotSpot Health Physics Code. We evaluated the dispersion of radioactive materials under consistent atmospheric conditions to assess their environmental and human health impacts. Our analysis was based on two parameters: sampling time and exposure duration. For sampling time, the Total Effective Dose Equivalent (TEDE) was measured at specific intervals. After 2000 min, the TEDE for LOCA was 47 Sv, significantly higher than 0.0033 Sv for the RDD within a 1 km² area. In the initial moments of the explosion, the doses were 340 Sv for LOCA and 0.042 Sv for RDD, showing a dramatic decrease over time. For exposure duration, the LOCA scenario, results in a TEDE of 150 Sv after one year. In contrast, the RDD leads to a TEDE of 0.17 Sv after the same period. The LOCA scenario results in higher radiation doses due to multiple radionuclides with varying decay rates, causing a rapid increase in dose. In contrast, the RDD scenario shows a slower dose accumulation due to the long half-life of ¹³⁷Cs. This study introduces an AI-enhanced approach to radiological assessments of LOCA and RDD incidents, using an Artificial Neural Network (ANN) model comprised of classification and regression sub-models. The classification sub-model accurately identifies the nature of the radiation event, while the regression sub-model estimates the distance of the explosion within 80 km radius from the explosion epicenter. With a predictive accuracy of 100 % in classification and over 99 % in regression, the model significantly improves the effectiveness and speed of emergency response strategies, offering critical advancements in radiological safety measures. The impact on human organs was more severe in LOCA, with doses to the liver, skin, lungs, thyroid gland, brain, and kidneys exceeding those from the RDD by factors ranging from 55 to 6000. The findings stress the need for strong safety measures, long-term monitoring, and preparedness, especially in regions like Yemen, while highlighting the potential long-term environmental and health impacts of nuclear incidents and the importance of effective response and recovery plans.