Shielding and activation studies around the proton beamline for the MYRRHA design


Shielding and activation studies around the proton beamline for the MYRRHA design

Ferrari, A.; Merk, B.; Konheiser, J.

Accelerator-driven systems (ADS) are one of the options studied for the transmutation of nuclear waste in the European Community. The design of sub-critical ADS requires high energy and high power proton accelerators, of the order of hundreds MeV and some MW for the proposed demonstration experiments. The use of high energy Mega-Watt proton beams, in combination with a nuclear reactor core operating in sub-critical or critical mode, presents many challenges for various aspects of the design. Radiation shielding and minimization of the induced activation are key points.
The present study has been done in the framework of the Central Design Team european project (CDT), which has the goal to design the FAst Spectrum Transmutation Experimental Facility (FASTEF), able to demonstrate efficient transmutation of high level waste and associated ADS technology. The heart of the system is a 100 MW LBE cooled reactor, working both in critical and sub-critical modes. A beamline aims to transport a 600 MeV, 4 mA proton beam produced by a linear accelerator up to the spallation target for the neutron production, which is located inside the reactor core. Based on the FASTEF design, the MYRRHA facility, which should enter the construction phase in 2015, will be built at SCK•CEN in Mol (Belgium). MYRRHA is conceived as a multi purpose facility: as technology demonstrator for lead-bismuth cooled fast reactor, as demonstrator for efficient transmutation, and as high flux irradiation facility for material testing and medical isotope production.
An extensive simulation study has been done to assess the shielding of the reactor building and the proton accelerator, as well as to fix the activation problems that have a heavy influence on the beamline and building design. Here the shielding assessment around the proton accelerator is presented, together with the optimization of the elements of the beamline that are devoted to the partial or total beam absorption (beam dump, collimators). This study has been fully carried out by using the FLUKA code, which has the unique feature to perform the transport of the residual radiation via a full Monte Carlo method, allowing in addition modifications in the geometry and material characterization from the prompt to the residual radiation transport. It will be shown how a suitable material configuration, with the introduction of low-activation materials, is a key issue: it will improve the accessibility and the long-term treatment of the irradiated elements allowing to maintain - and sometimes to improve – the shielding efficiency.

Keywords: Accelerator-driven systems; radiation transport; Monte Carlo; shielding

  • Lecture (Conference)
    International Conference of Transport Theory (ICTT-22), 12.-16.09.2011, Portland, Oregon, USA

Permalink: https://www.hzdr.de/publications/Publ-17426
Publ.-Id: 17426