Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: MYRRHA: Design of a windowless spallation target for a prototype accelerator driven system

Abstract

The development of a new nuclear installation that is able to fulfil the economical, social, environmental and technological demands, is a cornerstone for the future provision of sustainable energy. Accelerator Driven Systems (ADS) can pave the way for a more environmentally safe and acceptable nuclear energy production. Fundamental and applied R&D are crucial in the development of ADS technologies and demand the availability of appropriate prototype installations. In answer to this need and in order to update its current irradiation potential, the Belgian Nuclear Research Centre (SCK•CEN), in partnership with Ion Beam Applications s.a. (IBA), is launching the MYRRHA project. It is focussed on the design, development and realisation of a modular and flexible irradiation facility based on the ADS concept. Currently the study and preliminary conceptual design of the MYRRHA system is going on and the basic engineering is being performed. This study will define the final choice of the characteristics of the facility depending on the selected fields of application to be achieved. The MYRRHA concept, as it is today, is based on the coupling of a commercial proton accelerator with a spallation target surrounded by a subcritical neutron-multiplying medium. A 5 mA beam of accelerated protons of 350 MeV hits a liquid lead-bismuth spallation target and produces neutrons needed to deliver the primary neutrons for the neutron amplifier. During this process the beam deposits most of its energy into the Lead- Bismuth. The spallation target system consists of a flow loop designed to form a free surface with access to the downward directed beam and with contact to the beam line vacuum. No conventional window is foreseen between the free surface and the proton beam line vacuum in order to avoid engineering and operational difficulties. The windowless concept distinguishes MYRRHA from other ADS design activities and makes the design very challenging. Indeed, the geometry of the spallation target and more specifically the form of the free surface determines to a large extent the neutronic and thermal-hydraulic characteristics and the technological feasibility of the spallation target. The creation of a stable and controllable free surface flow capable of removing the heat deposited by the beam within the neutronic constraints is of main importance. This paper describes the design activities, which have been and are being performed to study the flow behaviour and to obtain an adequate design. These activities include both experiments and Computational Fluid Dynamics (CFD) calculations and their interaction.

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Reference:

Proceedings of a Committee Meeting (TCM) on “Core Physics and Engineering Aspects of Emerging Nuclear Energy Systems for Energy Generation and Transmutation” held in Argonne, Illinois, U.S.A., 28 November - 1 December 2000

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--1356, pp:279-293