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Severe Accident Modeling

The Fukushima Daiichi nuclear disaster of 2011 focused renewed attention beyond design factors to severe accident nuclear plant procedures and guidelines. A severe accident model integrated with the current plant full-scope simulator allows much more in-depth and realistic training on severe accident management guidelines. It allows realistic simulation of the impact on the reactor core and its impact on related plant systems, such as the containment building, auxiliary buildings and spent fuel pool.

GSE Systems' PSA-HD™ severe accident model simulation software allows user to:

  • Demonstrate safety of current plant designs to regulators, stakeholders and public.
  • Identify issues with current severe accident management guidelines (SAMG).

GSE's PSA-HD software integrates EPRI's Modular Accident Analysis Program (MAAP5) into a real-time simulation environment connected to all of the other plant systems in the simulator. This gives realistic plant behavior, allowing operators to:

  • Assess accident scenarios in a holistic environment;
  • Practice severe accident management guidelines; and
  • Experiment with alternative action scenarios.

Models developed in PSA-HD address both in-vessel and out-of-vessel progressions of a severe accident, up to the boundaries of the containment and auxiliary building. The model includes the neutronics calculations for the spent fuel, simulates possible pool structure damage, and integrates the supporting cooling systems and inventory.

In addition to single-unit events, Fukushima pointed out the need to look at site-wide events. To easily do that, GSE created PSA-HD Desktop severe accident model software.

This version of PSA-HD provides a multi-unit analysis capability while still providing realistic boundary conditions for plant performance. Visualization tools help analysis experts picture what is happening during an event. The PSA-HD provides a flexible, accurate platform modeling the entire nuclear plant site. Multiple units, including multiple reactor coolant systems (RCS), containments and auxiliary buildings, as well as interactions between them, can be simultaneously simulated. Different events and human interventions can be applied to different units, and the consequences can be evaluated at the site level.

*EPRI (www.epri.com) conducts research and development relating to the generation, delivery and use of electricity for the benefit of the public. An independent, nonprofit organization, EPRI brings together its scientists and engineers as well as experts from academia and industry to help address challenges in electricity, including reliability, efficiency, health, safety and the environment. EPRI does not endorse any 3rd party products or services. Interested vendors may contact EPRI for a license to MAAP 5.0.