From MYRRHA to XT-ADS: the design evolution of an experimental ADS system

The EUROTRANS project is an integrated project in the 6th European Framework Program in the context of Partitioning and Transmutation. It aims to deliver an advanced design of a small-scale Accelerator Driven System (ADS), XT-ADS, as well as the conceptual design of a European Facility for Industrial Transmutation, EFIT. Since 1998, SCK•CEN has been designing a multipurpose ADS for R&D applications – MYRRHA. In its 2005 version, MYRRHA consists of a proton accelerator delivering a 350 MeV*5 mA beam to a windowless liquid Pb-Bi spallation target that in turn couples to a Pb-Bi cooled, sub-critical fast core of 50 MW thermal power. The EUROTRANS partners have accepted the SCK•CEN offer to use MYRRHA as a starting basis for the XT-ADS design. Instead of starting from a blank page, this allowed optimizing an existing design towards the XT-ADS needs within the limits of safety requirements. Many options have been revisited in 2005 – 2006 and the framework is now set up. In this paper we present the general configuration of the XT-ADS core and primary system, with a particular focus on the evolution from MYRRHA and the rationale behind.