Sicherheitstechnische Analyse und Auslegungsaspekte von Abschirmungen gegen Teilchenstrahlung am Beispiel von Spallationsanlagen im Megawattbereich

This paper discusses the shielding of particle radiation from high current accelerators, spallation neutron sources and so called ADS-facilities ($\underline{A}$ccelerator $\underline{D}$riven $\underline{S}$ystems). ADS-facilities are expected to gain importance in the future for transmutation of long-lived isotopes from fission reactors as well as for energy production. In this paper physical properties of the radiation as well as safety relevant requirements and corresponding shielding concepts will be discussed. New concepts for the layout and design of such shielding will be presented. Focal point of this work will be the fundamental difference between conventional fission reactor shielding and the safety relevant issues of shielding from high-energy radiation. Key point of this paper is the safety assessment of shielding issues of high current accelerators, spallation targets and ADS-blanket systems as well as neutron scattering instruments at spallation neutron sources. Safety relevant shielding requirements will be presented and discussed. For the layout and design of the shielding for spallation sources computer base calculations methods are used. A discussion and comparison of the most important methods like semi-empirical, deterministic and stochastic codes will be presented. Another key point within the presented paper is the discussion of shielding materials and their shielding efficiency concerning different types of radiation. The use of recycling material, as a cost efficient solution, will be discussed. Based on the conducted analysis, flowcharts for a systematic layout and design of adequate shielding for targets and accelerators have been developed and will be discussed in this paper. By use of these flowcharts layout and engineering design of future ADS-facilities can be performed

Development of Neutron Extraction Plugs for HBS

Within the Jülich High Brilliance Neutron Source (HBS) project Forschungszentrum Jülich is developing a novel High Current Accelerator-driven Neutron Source (HiCANS). A special feature of the HBS is the concept of supplying neutrons to each instrument from their own adapted moderator, optimized for the desired neutron spectrum. The Moderator Plugs are an essential part of this concept. A neutron extraction plug may contain a cold moderator to modify the neutron spectrum towards lower energies as well as all necessary supply lines and control lines. In addition, it will either contain a neutron guide to transport a larger beam divergence or the beginning of a collimation setup for a highly collimated beam. An HBS target station demonstrator, which has been developed and build at the JULIC accelerator at Forschungszentrum Jülich, is providing neutrons to several experimental instruments since December 2022. The presentation will describe the development of extraction plugs for this demonstrator and the conclusions drawn for future extraction plugs at a possible HiCANS HBS

Technical Specification of the Small-Angle Neutron Scattering Instrument SKADI at the European Spallation Source

Small-K Advanced DIffractometer (SKADI is a Small-Angle Neutron Scattering (SANS) instrument to be constructed at the European Spallation Source (ESS). SANS instruments allow investigations of the structure of materials in the size regime between Angstroms up to micrometers. As very versatile instruments, they usually cater to the scientific needs of communities, such as chemists, biologists, and physicists, ranging from material and food sciences to archeology. They can offer analysis of the micro- and mesoscopic structure of the samples, as well as an analysis of the spin states in the samples, for example, for magnetic samples. SKADI, as a broad range instrument, thus offers features, such as an extremely flexible space for the sample environment, to accommodate a wide range of experiments, high-flux, and optimized detector-collimation system to allow for an excellent resolution of the sample structure, short measurement times to be able to record the internal kinetics during a transition in the sample, as well as polarized neutron scattering. In this manuscript, we describe the final design for the construction of SKADI. All of the features and capabilities presented here are projected to be included into the final instrument when going into operation phase

JULIC Neutron Platform, a testbed for HBS

The High-Brilliance neutron Source (HBS) project [1] develops a High-Current Accelerator-driven Neutron Source (HiCANS) with a pulsed proton beam, a peak current of 100 mA and an average power at the target of 100 kW. The concept of such a HiCANS was published some years ago [2] indicating the feasibility of such a facility with all of its components: high-current accelerator, target station with integrated moderator-reflector assemblies and neutron instruments. All components require engineering development and testing. The JULIC Neutron Platform was thus developed as a testbed for all components and the investigation of their interplay.The JULIC Neutron Platform uses a cyclotron providing a tunable pulsed proton beam with a low current but a variable frequency and pulse length to a spacious experimental area. A target station shielding is placed in its center with an empty inner core of 1 m3, able to accommodate different moderator-reflector assemblies as well as cryogenic moderators. The target station uses a tantalum target for the conversion of protons to neutrons and has eight spacious flexible ducts where moderator plugs for neutron extraction or blind plugs are placed.First beam on target was achieved in December 2022 with three instruments in operation: reflectometer, diffractometer and detector test stand. Further beamtime in 2023 is planned in order to investigate different cryogenic moderators, to estimate the performance of such a HiCANS and to perform further experiments.At UCANS, we will present the JULIC Neutron Platform, the experiments performed and the possibilities it offers.[1] P. Zakalek, et al, J. Phys.: Conf. Ser., 1401, 012010 (2020)[2] T. Brückel, et al. Conceptual Design Report Jülich High Brilliance Neutron Source (HBS), Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich (2020

A flexible target station for Hi-CANS

The advent of high-current accelerator systems launched the development of high -currentaccelerator-driven neutron sources (Hi-CANS) utilizing low energy nuclear reactions. Thisdevelopment can counteract the increasing shutdown of existing fission -based neutron sources and aresulting decline in available neutron beam days as well as establishing Hi-CANS as the nextgeneration of national neutron sources.A main component of a Hi-CANS is the target station used to convert protons into neutrons, tomoderate the neutrons to the required energy in the meV range, extract the neutrons to the instrumentswith the proper phase space volume as well as to shield the surrounding equipment .Within the High-Brilliance neutron Source (HBS) project, we are developing three target stationsoperated with a short pulse, medium pulse, and long pulse proton beam. The target stations have target/ moderator / reflector geometries optimized to the specific proton beam structure allowing to providetailored neutron beams to each individual neutron instrument. For this, a basic target station setup isused where just the core is modified to fulfill the specific requirements. Such a base layout of the targetstation reduces cost and effort and allows interchangeable composts making it highly modular andversatile.At UCANS 9, we will present the general design ideas of such a Hi-CANS target station and showthe flexibility it offers

KWS-1 high-resolution small-angle neutron scattering instrument at JCNS: current state

The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Jülich Centre for Neutron Science (JCNS) at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. The KWS-1 instrument was updated, from its active collimation apertures to the detector cabling. Most of the parts of the instrument were installed for the first time, including a broadband polarizer, a large-cross-section radio-frequency spin flipper, a chopper and neutron lenses. A custom-designed hexapod in the sample position allows heavy loads and precise sample positioning in the beam for conventional SANS experiments as well as for grazing-incidence SANS under applied magnetic field. With the foreseen in situ polarization analysis the main scientific topic of the instrument tends towards magnetism. The performance of the polarizer and flipper was checked with a polarized 3He cell at the sample position. The results of these checks and a comparison of test measurements on a ferrofluid in a magnetic field with polarized and nonpolarized neutrons are presented

The High Brilliance Neutron Source Target Stations

The advent of high-current accelerator systems launched the development of high-current accelerator-driven neutron sources (HiCANS) utilizing low energy nuclear reactions. This development can counteract the increasing shutdown of existing fission-based neutron sources and a resulting decline in available neutron beam days as well as establishing HiCANS as a next generation national neutron source. A main component of a HiCANS is the target station used to release neutrons, to moderate the neutrons to the required energy in the keV or meV range, to extract the neutrons to the instruments with the proper phase space volume as well as to shield the surrounding equipment. Within the High-Brilliance neutron Source (HBS) project, three target stations will be operated simultaneously with one long pulse, and two medium pulse proton beams. The target stations have target / moderator / reflector geometries optimized to the specific proton beam structure resulting in tailored neutron beams for different groups of neutron instruments. At the ECNS conference, we will present the general design ideas of such HiCANS target stations, show the flexibility they offer and present the resulting TMR assemblies for the HBS project. This work is part of the collaboration within ELENA and LENS on the development of HiCANS