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Science and Technology of Nuclear Installations
Volume 2009 (2009), Article ID 687634, 11 pages
Research Article

Modelling of HTR Confinement Behaviour during Accidents Involving Breach of the Helium Pressure Boundary

1Unit of Nuclear Safety Research, CIEMAT, Avenida Complutense, 22 28040 Madrid, Spain
2Pebble Bed Modular Reactor (Pty) Limited, 1279 Mike Crawford Avenue, 0046 Centurion, South Africa

Received 30 January 2009; Revised 18 May 2009; Accepted 4 June 2009

Academic Editor: Jim Kuijper

Copyright © 2009 Joan Fontanet et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Development of HTRs requires the performance of a thorough safety study, which includes accident analyses. Confinement building performance is a key element of the system since the behaviour of aerosol and attached fission products within the building is of an utmost relevance in terms of the potential source term to the environment. This paper explores the available simulation capabilities (ASTEC and CONTAIN codes) and illustrates the performance of a postulated HTR vented confinement under prototypical accident conditions by a scoping study based on two accident sequences characterized by Helium Pressure Boundary breaches, a small and a large break. The results obtained indicate that both codes predict very similar thermal-hydraulic responses of the confinement both in magnitude and timing. As for the aerosol behaviour, both codes predict that most of the inventory coming into the confinement is eventually depleted on the walls and only about 1% of the aerosol dust is released to the environment. The crosscomparison of codes states that largest differences are in the intercompartmental flows and the in-compartment gas composition.