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Science and Technology of Nuclear Installations
Volume 2012, Article ID 351985, 9 pages
http://dx.doi.org/10.1155/2012/351985
Research Article

Development of a Secondary SCRAM System for Fast Reactors and ADS Systems

1Institute for Advanced Nuclear Systems, SCK.CEN, 200 Boeretang, 2400 Mol, Belgium
2Laboratory for Agricultural Machinery and Processing, Katholieke Universiteit Leuven, 30 Kasteelpark Arenberg, 3001 Heverlee, Belgium
3Institute of Mechanics, Materials and Civil Engineering, Catholic University of Leuven, 2 Place du Levant, 1348 Louvain-la-Neuve, Belgium

Received 15 November 2011; Accepted 14 February 2012

Academic Editor: Alberto Talamo

Copyright © 2012 Simon Vanmaercke 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.

Abstract

One important safety aspect of any reactor is the ability to shutdown the reactor. A shutdown in an ADS can be done by stopping the accelerator or by lowering the multiplication factor of the reactor and thus by inserting negative reactivity. In current designs of liquid-metal-cooled GEN IV and ADS reactors reactivity insertion is based on absorber rods. Although these rod-based systems are duplicated to provide redundancy, they all have a common failure mode as a consequence of their identical operating mechanism, possible causes being a largely deformed core or blockage of the rod guidance channel. In this paper an overview of existing solutions for a complementary shut down system is given and a new concept is proposed. A tube is divided into two sections by means of aluminum seal. In the upper region, above the active core, spherical neutron-absorbing boron carbide particles are placed. In case of overpower and loss of coolant transients, the seal will melt. The absorber balls are then no longer supported and fall down into the active core region inserting a large negative reactivity. This system, which is not rod based, is under investigation, and its feasibility is verified both by experiments and simulations.