Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Calculational approach and results of the safe shutdown earthquake event for the pebble bed modular reactor

Conference ·
OSTI ID:22039745
; ;  [1]
  1. Reactor Design and Fuel Management Group, PBMR Pty Ltd., PO Box 9396, Centurion, 0046 (South Africa)
The Pebble Bed Modular Reactor (PBMR) concept can be described as a high-temperature helium-cooled, graphite-moderated pebble-bed reactor with a multi-pass fuelling scheme. The fuel is contained in 6 cm diameter graphite spheres containing carbon-based coated UO{sub 2} kernels. An online fuel reload scheme is applied with the fuel spheres being circulated through the reactor. The pebble-bed reactor core thus consists of fuel pebbles packed in the core cavity in a random way. The packing densities and pebble flow is well known through analysis and tests done in the German experimental and development program. The pebble-bed typically has a packing fraction of 0.61. In the event of an earthquake this packing fraction may increase with the effect that the core geometry and core reactivity will change. The Safe Shutdown Earthquake (SSE) analysis performed for the PBMR 400 MW design is described in this paper, and it specifically covers SSE-induced pebble-bed packing fractions of 0.62 and 0.64. The main effects governing the addition of reactivity in the SSE event are the changes in core neutronic leakage due to the decreased core size and the decreased effectiveness of the control rods as the pebble-bed height decreases. This paper describes the models, methods and tools used to analyse the event, the results obtained for the different approaches and the consequences and safety implications of such an event. (authors)
Research Organization:
American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
OSTI ID:
22039745
Country of Publication:
United States
Language:
English