17. Concrete buffers for the containment of high-level radioactive waste: casting conditions and THM behaviour

Title: 17. Concrete buffers for the containment of high-level radioactive waste: casting conditions and THM behaviour
Author(s): B. Craeye, G. De Schutter, H. Van humbeeck, W. Wacquier, A. Van cotthem
Paper category : conference
Book title: NUCPERF 2009 - Long Term Performance of Cementitious Barriers and Reinforced Concrete in Nuclear Power Plants and Waste Management
Editor(s): V. L'Hostis, R. Gens, C. Gallé
Print-ISBN: 978-2-35158-072-1
e-ISBN: 978-2-35158-087-5
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 153 - 166
Total Pages: 14
Nb references: 12
Language: English

Abstract: In the framework of the feasibility demonstration program of the Belgian Supercontainer concept, extensive laboratory tests and finite element calculations were performed to accurately simulate the Thermo Hydro Mechanical (THM) behaviour of the Supercontainer concrete Buffer during construction and to predict and prevent early-age crack formation.

The Supercontainer is the current Belgian reference concept for the final disposal of heat emitting waste designed by ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials. The concept is based on a multiple barrier system where every component has its own specific safety function or role requirements. In this reference concept, the vitrified High Level Waste (HLW) and Spent Fuel assemblies (SF) are encapsulated into a watertight carbon steel overpack surrounded by a cylindrical concrete Buffer which will then be disposed in a deep clay layer.

The laboratory test program was finalised and has allowed to characterize the mechanical, thermal and maturity-related behaviour of the two types of concrete currently considered for the choice of the cementious Buffer: a Self-Compacting Concrete (SCC) and a Traditional Vibrated Concrete (TVC). The measured data were then used to simulate the behaviour of the concrete Buffer during construction by using a 2.5D (2D axisymmetrical) thermal and crack modelling program. This includes the fabrication of the concrete, the emplacement of the heat-emitting waste canisters, and the closure of the container. That way, it is possible to take into account different casting conditions. The simulations showed that through-going cracks in the concrete Buffer, which will considerably ease the transport mechanisms inside the Supercontainer and reduce the radiological shielding role of the buffer, are not expected.

Online publication: 2009-11-16
Publication type : full_text
Public price (Euros): 0.00