Source term dispersion analysis and construction of the probabilistic dispersion map around the Peach Bottom Unit-2 plant using the ASTEC and JRODOS codes

• A short-term Station BlackOut (SBO) severe accident analysis for Peach Bottom Unit-2 NPP was conducted using the ASTEC code. • The fuel inventory of the new GE14 10 × 10 assembly was calculated using the CASMO5 code. • A dispersion analysis database for the year 2021 was generated, incorporating a total of 60,000 JRODOS simulations. • Seasonal total gamma effective dose rate distribution maps were established by applying the central limit theorem. • The spatial distribution of dose rates provides valuable insights for enhancing emergency planning. National regulatory authorities and Emergency Preparedness teams require accurate source term predictions to safeguard the public in the event of radiological emergencies, such as severe accidents at Nuclear Power Plants (NPPs). Consequently, reliable assessments of the radiological impacts of hypothetical Severe Accidents (SA) at NPPs are essential. In order to meet this need, a unique and robust platform of simulation codes has been developed at the Karlsruhe Institute of Technology (KIT) to assess the source term data and corresponding radiological consequences of severe accidents. This platform utilizes the CASMO5 code to calculate the fuel inventory in the reactor core and the European reference Accident Source Term Evaluation Code (ASTEC), developed by IRSN, to analyze the severe accident sequence, from initiation to the release of fission products into the environment. The source term data calculated by ASTEC is then used by the JRODOS code, developed by KIT, to assess the radiological effects of the dispersion. In this study, the described platform is used to evaluate the radiological consequences of a Station BlackOut (SBO) scenario at the Peach Bottom Unit-2 NPP. JRODOS analyses use representative dates to assess radiological impacts, as daily evaluations which are considers the possible each starting point computationally impractical. A methodology was developed to assess severe accident consequences for each grid around Peach Bottom Unit-2 NPP. This approach offers a detailed view of the accident’s scope across the region, aiding in the development of appropriate plans for the early and intermediate phases of the accident. Thus, the proposed methodology provides valuable and detailed insights for evaluating emergency preparedness and response actions in the event of a SA at an NPP.