Publications: Conference

Author(s) :R. Luis (ITN), Y. Romanets (ITN), J.C. David (CEA), D. Ene (CEA), I. F. Goncalves (ITN), Y. Kadi (CERN), C. Kharoua (CERN), F. Negoita (NIPNE), R. Rocca (CERN), L. Tecchio (INFN), P. Vaz (ITN)

One of the EURISOL-DS (The EURopean Isotope Separation On-Line Radioactive Ion Beam – Design Study) objectives is to provide a safe and reliable facility layout meeting the following operational parameters: 1. 4 MW proton beam of 1 GeV impinging on the Hg converter 2. High neutron source (~3x1016 neutrons/s ) generated by spallation reactions 3. Fission rate on a fissile target (235U) above 1015 fissions/s In this work, the state-of-the-art Monte Carlo codes MCNPX and FLUKA were used to assess the neutronics performance of the target station but also provide estimations of dose rate and activation for assessing the safety conditions prevailing in the facility. This work aimed to identify the facility regions and components (systems) which may need to be improved or even redesigned. For this purpose, an analysis of the activities and associated dose rates of each of the elements (cladding, cooling systems, cables etc.) of the converter and of the fission targets was carried out, during operation and after shutdown, for diverse cooling times. The results obtained from the safety and radioprotection studies show high activation values in some areas that will require the adjustment of the composition of some materials. Such specific conditions for the operation and maintenance of the facility may require an increase of the complexity of some supply systems. (NEUDOS-11)

Author(s) :R. Luis (ITN), Y. Romanets (ITN), J. Bermudez (INFN) , J.C. David (CEA), D. Ene (CEA), I. F. Goncalves (ITN), Y. Kadi (CERN), C. Kharoua (CERN), F. Negoita (NIPNE), R. Rocca (CERN), L. Tecchio (INFN), P. Vaz (ITN)

The EURISOL (The EURopean Isotope Separation On-Line Radioactive Ion Beam) project aims at producing high intensity radioactive ion beams produced by neutron-induced fission on fissile targets (235U) surrounding a liquid mercury converter. A proton beam of 1GeV and 4MW impinges on the converter, generating, by spallation reactions, high neutron fluxes that induce fission in the surrounding fissile targets. In this work the state-of-the-art Monte Carlo codes MCNPX and FLUKA were used to assess the neutronics performance of the system, which geometry, inspired in the MAFF concept, allows a versatile manipulation of the fission targets. The first objective of the study was to optimize the geometry and the materials used in the fuel and reflector elements of the system, in order to achieve the highest possible fission rates. Indeed, it is shown that the appropriate combination of fission target material and surrounding reflector material leads to the aimed value of 1015 fissions/s per fission target. The second part of this work is related to safety parameters. Dose rate and activation calculations were carried out in order to identify the necessary shielding and access restrictions for each section of the entire facility, including maintenance, storage and remote control spaces. The results presented in this work indicate that there are good prospects for the feasibility of the EURISOL fission target, in its new configuration, considered in this work. The safety analysis indicates that some points of the facility need special attention from the safety and radioprotection points of view. (ICENES'09)

Author(s) :C. Kharoua(1), Y. Kadi(1), L. Blumenfeld(1), W Wagner(2), K. Thomsen(2), R. Milenkovich(2), S. Dementjevs(2), E. Platacis(3), K. Kravalis(3), A. Zik(3) (1)CERN (European Laboratory for Particle Physics),CERN CH - 1211 Geneva 23, Switzerland (2)PSI(Paul Scherrer Institute); Paul Scherrer Institute , 5232 Villigen PSI, Switzerland (3)IPUL (Institute of Physics of University of Latvia); 32 Miera iela, Salaspils, LV-2169 Latvia

The European Isotope Separation On-Line Radioactive Ion Beam Facility (EURISOL) is set to be the ‘next-generation’ European Isotope Separation On-Line (ISOL) Radioactive Ion Beam (RIB) facility. It will extend and amplify current research in nuclear physics, nuclear astrophysics and fundamental interactions beyond the year 2013. In EURISOL, four target stations are foreseen, three direct targets of approximately 100 kW of beam power and one multi-MW liquid metal proton-to-neutron converter, all driven by a high-power particle accelerator. In the aforementioned multi-MW target assembly, high-intensity RIBs of neutron-rich isotopes will be obtained by inducing fission in several actinide targets surrounding a liquid metal spallation neutron source. This presentation summarises the work carried out for the Multi Megawatt target station of the EURISOL Design Study with particular attention to the coupled neutronic of the liquid converter and the overall performance of the facility, which will sustain fast neutron fluxes of the order of 1014 n/cm2/s. The production of radionuclides in the actinide targets as well as in the liquid metal are also evaluated, showing that the targeted 1015 fissions/s can be achieved. Some of the greatest challenges in the design are the high power densities, entailing large structural stresses, and the heat removal, requiring detailed thermo-hydraulics calculations. Some result of a validation experiment of the Coaxial Guided Stream Design will be presented. Alternatively, a windowless target configuration has been proposed, based on a liquid mercury transverse film design. With this design, higher power densities and fission rates may be achieved, also avoiding the technical issues related to the beam window. Acknowledgements I acknowledge the financial support of the European Commission under the 6th Framework Programme “Research Infrastructure Action Structuring the European Research Area” EURISOL DS Project Contract no. 515768 RIDS. The EC is not liable for any use that may be made of the information contained herein.

Author(s) :D. Ridikas (1) for Task 5 & A. Herrera-Martínez (2) for Task 2 of the EURISOL DS project (1) CEA Saclay, DSM/DAPNIA, 91191 Gif-sur-Yvette, France (2) CERN, CH-1211 Geneva 23, Switzerland

The European Community has launched the design study for a next generation RIB facility able to increase by a few orders of magnitude, the exotic beam intensity and availability in Europe. Forty institutes and laboratories within Europe, North America and Asia are taking part in this consortium, named EURISOL DS project (European Isotope Separation On Line Design Study). In EURISOL, four target stations are foreseen, three direct targets of approximately 100 kW of beam power and one multi-MW (MMW) target assembly, all driven by a high-power particle accelerator. In this MMW station, high-intensity RIBs of neutron-rich isotopes will be obtained by inducing fission in several actinide targets surrounding a liquid metal spallation neutron source. The envisaged increase in RIB intensities at EURISOL means a drastic increase of the radioactive inventory and corresponding radioprotection related issues. Safety aspects of the future RIB production targets (aiming at a few ~1015 fissions/s) will become decisive in limiting the beam intensities, in selecting the production method and materials, and in the final cost of the facility. New technical challenges arise that will in most cases also critically affect the safety approval procedures. The handling and disposal of open radioactive high intensity RIB production targets (e.g. UCx, ThCx) including liquid Hg converter target is yet unexplored. Equally, containment of gaseous radioactivity and its migration will be crucial in the same context. The progress made so far on most of these issues within Task 2 “multi-MW target” and Task 5 “Safety and Radioprotection” will be summarized.

Author(s) :C. Kharoua

This presentation will present some of the greatest challenges in the design of this high power spallation sources with a special attention on the high power densities, entailing large structural stresses, and the heat removal, requiring detailed thermo-hydraulics calculations. Alternatively, a windowless target configuration has been proposed, based on a liquid mercury transverse film design. With this design, higher power densities and fission rates may be achieved, also avoiding the technical issues related to the beam window. In the second part of this presentation a brief summary of the actinide targets will be presented. The thermal simulations as well as the fission rates and isotopes production simulation are important calculation to evaluate the capability of the Multi-Megawatt target station.

Author(s) :C. Kharoua

This presentation summarises the work carried out for the Multi Megawatt target station of the EURISOL Design Study with a special attention to the coupled neutronics of the liquid converter and fission target (MAFF/PIAFE design like) and the overall performance of the facility, which will sustain fast neutron fluxes of the order of 1014 n/cm2/s. The production of radionuclides in the actinide targets as well as in the liquid metal are also evaluated, showing that the targeted 1015 fissions/s can be achieved.

Author(s) :Y. Romanets (1), I. Goncalves (1), A. Herrera-Martinez (2), Y. Kadi (2), C. Kharoua (2), J. Lettry (2), M. Lindroos (2), P. Vaz (1) (1) ITN- Estrada Nacional 10, 2686-953, Sacavém - Portugal (2) CERN- CH-1211, Genève 23, Switzerland

The EURISOL (The EURopean Isotope Separation On-Line Radioactive Ion Beam) project aims at producing high intensity radioactive ion beams produced by neutron induced fission on a fissile target (235U) surrounding a liquid mercury converter. A proton beam of 1 GeV and 4 MW impinges on the Hg converter generating by spallation reactions high neutron fluxes. In this work the state-of-the-art Monte Carlo codes MCNPX and FLUKA were used to assess the neutronics performance of the system which geometry, inspired from the MAFF concept, allows a versatile manipulation of the fission targets. The objective of the study was to optimize the geometry of the system and the materials used in the fuel and reflector elements of the system, in order to achieve the highest possible fission rate.

Author(s) :Adonai Herrera-Martinez*, Yacine Kadi, Morteza Ashrafi-Nik, Karel Samec, Janis Freibergs, Ernests Platacis

The European Isotope Separation On-Line Radioactive Ion Beam project (EURISOL) is set to design the ‘next-generation’ European Isotope Separation On-Line (ISOL) Radioactive Ion Beam (RIB) facility. It will extend and amplify current research on nuclear physics, nuclear astrophysics and fundamental interactions beyond the year 2010. In EURISOL, four target stations are foreseen, three direct targets of approximately 100 kW of beam power and one multi-MW target assembly, all driven by a high-power particle accelerator. In this high power target station, high-intensity RIBs of neutron-rich isotopes will be obtained by inducing fission in several actinide targets surrounding a liquid metal spallation neutron source. This article summarises the work carried out within Task 2 of the EURISOL Design Study, with special attention to the coupled neutronics of the mercury proton-to-neutron converter and the fission targets. The overall performance of the facility, which will sustain fast neutron fluxes of the order of 1014 n/cm2/s, is evaluated, together with the production of radionuclides in the actinide targets, showing that the targeted 1015 fissions/s can be achieved. Some of the greatest challenges in the design of high power spallation sources are the high power densities, entailing large structural stresses, and the heat removal, requiring detailed thermo-hydraulic calculations. The use of a thin martensitic steel beam-window and a well-controlled mercury flow has been shown to reduce the von-Misses stress in the former below the 200 MPa limit, with reasonable maximum flow rates of ~6 m/s. Alternatively, a windowless target configuration has been proposed, based on a liquid mercury transverse film. With this design, higher power densities and fission rates may be achieved, avoiding the technical difficulties related to the beam window. Experimentally, several tests have been performed at IPUL (Riga, Latvia) in order to study the stability of the liquid metal flow and validate the mercury loop design.

Author(s) :Adonai Herrera-Martínez Yacine Kadi

In EURISOL, the production of high-intensity RIBs of specific neutron-rich isotopes is obtained by inducing fission in large-mass actinide targets. In our contribution, the use of Uranium targets is shown to be advantageous to other materials, such as Thorium. Therefore, in order to produce fissions in 238U and reduce the Plutonium inventory, a fast neutron energy spectrum is necessary. The large beam power required to achieve these RIB levels requires the use of a liquid proton-to-neutron converter. This article details the design parameters of the converter, with special attention to the coupled neutronics of the liquid converter and fission target. Calculations performed with the Monte Carlo code FLUKA, suggest the use of a 1 - 2 GeV proton beam and a compact Mercury converter, surrounded by the fission target for efficient use of the spallation neutrons.