Impact of a security event at a TRIGA reactor

• The fission product inventories of the TRIGA reactor were evaluated by Origen-Arp.
• A security event was considered to happen in the reactor.
• Atmospheric dispersion is done by RASCAL, HOTSPOT and GENII to evaluate the dose.
• A significant difference among codes’ results is found.
• Emergency actions for the near residential area are founded.

The aim of this work is the study of the impact of security-related events and their consequences for research reactors, with particular emphasis on the off-site effects. The study case is done for the ENEA-Casaccia TRIGA RC-1 research reactor near Rome. The RC-1 Safety Report includes three different safety-related accident scenarios, namely the insertion of a step of positive reactivity, the uncontrolled extraction of all control rods at start-up or during a power variation and the emptying of the reactor pool. None of these scenarios imply radioactive releases at all. In this work, the focus is instead the description of the worst case scenario related to a security event and its consequences. Several possible scenarios have been analysed, however, the physical protection measures deter intrusions and, as shown by the Safety Report, even sabotage actions with major effects such as, the emptying of the reactor pool have no consequences on the fuel integrity. For these reasons, the worst security-related scenario considered in this work is a large plane crash with the complete destruction of the reactor hall and the reactor core. Propagation of the source term to the environment and the effective dose calculations have been performed using RASCAL, HOTSPOT and GENII codes following the ICRP-60 standards.