Evolution of neutron beam instrumentation in Argentina: from early Neutron Physics spectrometers to the LAHN Facility at RA-10 (Instrument design and construction)

• Javier Santisteban (Comisión Nacional de Energía Atómica-LAHN)

The Atomic Energy Commission of Argentina started the development of neutron beam instruments in the early 1970s, by the design, construction and testing of a 17 metres long time-of-flight neutron spectrometer dedicated to Neutron and Reactor Physics studies, using a pulsed neutron source at the 25 MeV electron linear accelerator of Centro Atómico Bariloche. Sustained work on the design, construction, installation and operation of neutron beam instrumentation continued until the present day, with additional beamlines installed at the Bariloche LINAC and at the CNEA research reactors in Buenos Aires and Bariloche, broadening the focus to multidisciplinary applications in materials science, technology, and health. The experience gained over the years contributed to the definition of the scientific and technical scope of the project for the Argentine Neutron Beam Laboratory (LAHN), which will use the neutron beams of the RA-10 reactor for the provision of neutron techniques to the Argentine and Latin American user communities. This contribution will present a historical and technical overview of operational and decommissioned neutron instruments in Argentina, emphasizing their design goals, main achievements, besides key technical and operational challenges. Furthermore, it will introduce the scientific scope and main technical requirements of the initial instrument suite of the LAHN, and the requirements posed on the neutron delivery system to provide a complete suite of fourteen instruments for the full scope of the laboratory.

NOMAD Secondary Collimation Project Update: From Additive Manufacturing Concepts to a B₄C Sheet-Metal Design (Neutron optics)

• Cassandra Scully (ORNL)

This presentation summarizes the development and deployment of upgraded secondary collimators for the NOMAD diffractometer at the Spallation Neutron Source, building on previously reported prototype studies. The project initially investigated an additively manufactured design based on the hypothesis that hydrogen-rich materials could provide sufficient neutron attenuation through scattering without requiring neutron-absorbing materials. Experimental testing demonstrated that this approach was ineffective, as scattering from the collimators increased background and degraded instrument performance. Subsequent prototype studies evaluated boron-loaded paint, cadmium coverings, and alternative grid spacings, leading to a sheet-metal secondary collimator design incorporating boron carbide (B₄C) as the neutron absorber. The completed system has been installed on NOMAD with favorable results, improving collimation performance while meeting requirements for manufacturability, assembly, and integration with the detector array. This presentation discusses the design evolution, experimental findings, and successful implementation of the final collimator system.

LEU Fission Plate Design for Order-of-Magnitude Enhancement of UCN Density at LANL (Neutron optics)

• Christopher O'Shaughnessy (Los Alamos National Laboratory)

Ultracold neutrons (UCN) enable precision measurements of fundamental neutron properties through their unique ability to be stored and manipulated at velocities below 5-7 m/s. At sufficient UCN densities, these measurements can probe beyond-standard-model (BSM) physics with sensitivity comparable to or exceeding high-energy collider experiments, while also enabling novel applications in surface science characterization. Current UCN sources are limited by maximum allowable target irradiation currents, constraining achievable densities. We present a low-enriched uranium (LEU) fission plate design that enhances UCN production by a factor of 8-15 without increasing beam current. This approach leverages uranium’s high fission cross-section to amplify the primary neutron flux output from the UCN production target. Our presentation will detail the design optimization, including: neutron transport modeling, thermal management solutions for elevated heat loads, fabrication methodology, operational lifetime projections, and integration with the existing UCN source design. The fission plate configuration provides an optimal neutron source while mitigating typical challenges associated with high-intensity neutron environments, paving the way for next-generation fundamental physics measurements.

Beam axis – Definition, communication, best practice (Neutron optics)

• Janno Büchi (SwissNeutronics)

The beam axis of any neutron instrument is a very important property, with wide-ranging implications for beam shaping, shielding, and component interfaces. New instruments and institutes employ more complex trajectories for their neutron beams to further optimise performance and for operational reasons. While this is not inherently a problem, the precise definition and communication of the axis- and interface-specifications to suppliers is a key challenge to ensure components meet scientists’ requirements. Due to the complex dependencies between subsystems, errors or uncertainties can delay a project significantly. In this presentation, I outline the aspects of a neutron guide system design affected by the axis layout. I demonstrate different approaches to the beam axis definition used by customers in the past, potential pitfalls, and propose initial guidelines towards best practices that accommodate the uniqueness of individual instruments while enabling clearer, more efficient communication between instrument designers and component suppliers

Neutron Guide Replacement under Extreme Space Constraints (Mechanical structures)

• Elbio Calzada (Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II))

The REFSANS horizontal reflectometer uses a unique system of focused neutron guides to the cold source to enable advanced reflectometry studies. These rectangular-cross-section guides are twisted and rotate through 90 degrees over a distance of 36 meters. During a recent reactor shutdown, work began on the complete replacement of this specialized guide system, which was already 20 years old. However, the decommissioning and reinstallation process faced severe spatial and structural constraints, particularly within a transition zone known as the Kasematte. This specific room presents extraordinary logistical hurdles: it is accessible only via a single 80 cm wide entrance, completely lacks crane infrastructure, and possesses a ceiling unsuited for suspended loads. Furthermore, the handling is complicated by two adjacent beamlines with heavy shielding located just 60 cm above the floor. Navigating this environment required maneuvering vacuum vessels weighing two tones each, while maintaining a critical clearance distance between the guides of only 0.5 mm. This presentation describes the technical solutions, handling equipment, and the procedures implemented to address these geometric and weight requirements. Additionally, the operational experiences and lessons learned from this instrument upgrade under confined conditions will be discussed.

Novel Collimator Features for SKADI at ESS: Beam Shaping and Operational Efficiency (Instrument design and construction)

• Sylvain Desert (ESS)

**Abstract** This presentation introduces the new design features implemented in the collimator of the European Spallation Source small-angle neutron scattering instrument SKADI. The first part focuses on the flexible beam-shaping concept achieved through a set of adjustable slits, allowing a wide range of experimental configurations. The integration of a VSANS option is also presented, extending the instrument capabilities toward very small scattering vectors. The second part describes the practical and ergonomic features of the telescopic collimator nose. Its foldable design greatly facilitates access during maintenance operations, while its manual extension and retraction can be performed smoothly and with minimal effort, even when the collimator is under vacuum. These developments aim to improve both instrument performance and operational usability for users and technical staff.

AUSTRALIAN CENTRE FOR NEUTRON SCATTERING DEVELOPMENT PLANS (Neutron optics)

• Stan Lee (ANSTO)

ANSTO’s Australian Centre for Neutron Scattering (ACNS) currently operates 15 neutron beam instruments. Throughout its continued operation, development plans for the ACNS have evolved to meet the increasing user and capability demand. With insufficient space for neutron beam instruments, sample environment, laboratories, offices, as well as mechanical, electrical, and electronics workspaces, an expansion of the Neutron Guide Hall has been identified and is currently in planning stages. The extension will allow for new neutron guides to be installed, paving the way for additional neutron instruments. Furthermore, a second guide hall is being scoped, with an intended location on the opposite side of the OPAL Reactor to that of the first guide hall. The second guide hall is anticipated to consist of new instruments that meet the needs of the regional scientific community which are not yet met by our existing instrument suite. This will necessitate significant modifications to the instruments immediately adjacent to the reactor face. One such option is the introduction of a new horizontal cold neutron source at the existing thermal guide 4 location. Also presented are a selection of development projects currently in progress, including a new curved Helium-3 detector for the Wombat diffractometer, neutron optics for the Pelican time-of-flight spectrometer, and facility-wide upgrades to control systems for the safety interlocks and choppers.

Development of a detector housing for the SKADI instrument at ESS (Detectors)

• Romuald Hanslik (Forschungszentrum Juelich GmbH)

Forschungszentrum Juelich has developed a new detector system for the SKADI instrument at the ESS neutron source in Sweden. The detector system is based on Li6 scintillator area detectors with multi-anode photomultipliers. The design incorporates two movable detector housings within a vacuum tube, allowing for measurements at various positions. The readout electronics, housed within the detector housing, are actively cooled via external supply lines. Building on the 2025 presentation at DENIM XIV, this year's session focuses on the challenges and insights gained from designing specialized detector housings with integrated cooling systems. It will also discuss the development and deployment of a custom installation tool used to position the detector inside a vacuum vessel. Finally, the presentation will highlight key lessons learned from manufacturing critical detector components.

FPGA-BASED MULTICHANNEL SIGNAL GENERATOR FOR EMULATION OF NEUTRON DETECTOR (Detectors)

• Alejandro Pinto (CNEA, UTN-HAEDO)

The Argentine Neutron Beam Laboratory (LAHN) will incorporate the Advanced Neutron Diffractometer for Engineering and Science (ANDES), one of the instruments developed entirely by the National Atomic Energy Commission (CNEA), which will operate using neutron beams provided by the RA-10 multipurpose reactor. The ANDES position-sensitive neutron detector is a key component of the instrument; whose output is processed by a data acquisition chain comprising front-end electronics, data acquisition hardware, and reconstruction software to determine the impact position of each neutron. This work presents the design basis and current development status of a device that emulates the pulses generated by the detector in response to neutron interactions, producing signals equivalent to those obtained during real measurements. The system reproduces both the amplifier output signals and the constant fraction discriminator (CFD) output signals of the detector. It is implemented in a module compliant with the Nuclear Instrumentation Module (NIM) standard in both mechanical dimensions and power supply. In addition, it includes a custom-developed application that allows the user to define the impact position of an individual neutron or generate predefined event patterns. The system requirements were established through a comprehensive study of the detector operation and the response of its associated electronics, complemented by preliminary tests aimed at characterizing the signals to be emulated. The objective of this development is to provide a tool for validating and developing the complete data acquisition and processing chain without requiring the availability of either the detector or a neutron beam, thereby facilitating integration, maintenance, and future upgrades of the instrument.

Cartographic measurements of neutron backgrounds at the Institut Laue-Langevin (Detectors)

• Charles Dewhurst (Institut Laue Langevin, Grenoble, France)

Using a portable thermal neutron detector array, we have performed cartographic measurements of the neutron background in the reactor and experimental halls of the Institut Laue-Langevin. Four panels of twelve tube detectors have been mounted on a movable trolley, together with the required electronics and computing hardware, forming a mobile neutron detection instrument. The detectors are shielded at the rear and arranged in a square geometry, allowing directional information, as well as magnitude and temporal variations of neutron backgrounds, to be obtained. These measurements can be correlated with operational parameters such as reactor power and the open/closed status of neutron shutters, guides and instrumentation. Depending on the instrument class, experimental practices and, in some cases, oversights in design and construction, some neutron instrumentation can release non-negligible neutron fluxes into the surrounding environment. These neutrons form a diffuse ‘neutron gas’ or ambient neutron field which, while generally of little radiological significance, can increase and modify the background observed by neighbouring instruments. Recent infrastructure modifications implemented to comply with earthquake resistance requirements have significantly altered the shielding of neutron guides passing from the reactor building to the guide halls. These changes have resulted in a degraded environmental neutron background, negatively affecting the performance of some instruments. Cartographic measurements using thermal neutron detectors allow the spatial distribution and potential sources of environmental neutrons to be identified, providing a route towards reducing neutron background and improving instrument performance.

Seismic Analysis Criteria and Methodology for Shielding Components in Neutron Instruments: A Case Study (Mechanical structures)

• Agustín Hernández Rocha (Comisión Nacional de Energía Atómica)

One of the main challenges in the design of neutron scattering instruments is the design of their shielding structures. These must provide adequate radiological protection for the working area surrounding the instrument, while also being mechanically feasible to fabricate and having their structural capacity verified according to nuclear industry standards. This work presents the seismic verification criteria and methodology developed for the shielding and support structures of the ANDES instrument (Advanced Neutron Diffractometer for Engineering and Science), and illustrates its application through a representative case study. The methodology is based on the equivalent static method, in which the seismic demand is represented by an equivalent static force derived from the peak acceleration of the floor response spectra (or the zero-period acceleration, ZPA, when the component's fundamental frequency exceeds 40 Hz), affected by a conservative static coefficient. Two seismic levels are considered, an Operating Basis Earthquake (SL-1) and a Safe Shutdown Earthquake (SL-2), each associated with a different service level and corresponding stress-intensity acceptance limits, following ASME Section III NF (Design by Analysis) criteria. In addition to stress verification, rigid-body motion checks (sliding and rocking/overturning) are performed following simplified ASCE 4 procedures, comparing the seismic shear and overturning moment at the support interface against the frictional and restoring resistance, respectively. A key modeling challenge addressed in this work concerns the mechanical interaction between shielding blocks. Since the individual shield boxes rest on one another without rigid connection, two limiting modeling assumptions are possible: treating the interfaces as fully bonded, which overestimates stiffness and does not reflect the real load path between parts, or treating them as fully separated (unbonded), which increases flexibility and can amplify seismic demand disproportionately. The friction coefficient and the interlocking interfaces between surfaces (such as pins or coupling plates) play a central role in this assessment, since they govern whether adjacent blocks slide or move relative to one another under seismic acceleration. The work discusses how these considerations are combined in practice, using hand calculations to bound the problem and finite element models to refine the stress verification where geometry and boundary conditions are more complex. Results are presented for the Polychromatic Beam Shielding (SS 0204) of ANDES as an example case. The results obtained show that the developed methodology allows the seismic behavior of the shielding to be characterized with an adequate level of confidence, combining analytical and numerical tools to identify the governing failure modes. These results illustrate how the combination of simplified analytical checks and finite element modeling supports a practical, conservative seismic qualification process for shielding components.

Scattering Chamber Design for the Cold Neutron Direct Geometry Inelastic Spectrometer at CSNS-II (Mechanical structures)

• Songwen Xiao (Institute of High Energy Physics, Chinese Academy of Sciences)

The cold neutron direct geometry inelastic spectrometer(CNIS) is one of the planned instruments for the CSNS-II project. The scattering chamber, located at the instrument's end, features a semi‑fan shape covering an angular range of –30° to 138°, with a volume of ~75 m³, a height of ~4 m, and is made of stainless steel. The chamber provides interface for sample environment, supports installation of 1‑inch ³He tubes (3 m length), and maintains a high‑vacuum, low‑background environment at 5×10⁻³ Pa. Detectors operate in “airbox” mode: high‑voltage interfaces, preamplifiers, and digital circuit boards are housed in airtight boxes, connected externally via bellows; the tube high voltage is independent of chamber vacuum. Inside, 12 detector support bases (each accommodating 4 detector units, each unit containing 8 ³He tubes) and one circular guide rail are installed. A maintenance carriage on the rail rotates around the centre to facilitate installation and removal of detector units. Four DN400 top flanges allow crane‑assisted handling of detector units. Eleven isolating plates are mounted between the detector support bases. The detailed design is complete, and the chamber is currently under fabrication. This abstract presents the structural design, detector maintenance procedures, and vacuum system rationale.

Shaping the Future of Neutron Science: ILL's Science Strategy and Long-Term Vision (Project management)

• Jacques Jestin (Institut Laue Langevin)

Following the completion of the Endurance programme, the ILL is the world's leading facility for neutron science, offering the largest suite of state-of-the-art instruments and operating up to 170 days per year. I will present the ILL's recent achievements in instrument operation, neutron technology, sample environment, and data science. We have developed a new Science Strategy for the coming years, introducing initiatives such as Science Hubs and Showcase Experiments to strengthen the contribution of neutron science to addressing major societal challenges and to reinforce collaboration with industry. We are also developing the Institute's long-term strategy to build the momentum needed to sustain ILL's operation over the coming decades while helping to shape the future European neutron landscape.

Challenges faced when 3D printing shielding components for neutron instruments (Shielding)

• Joel Allan Hodder (ISIS)

3D printing is a proven manufacturing method used in all industries, enabling manufacture of forms that would be near impossible using traditional manufacturing techniques. Neutron instruments often require components with demanding geometries and quality requirements, such as thin-walled collimators. In this work, new techniques have been developed to overcome some of the challenges faced when 3D printing with custom-made neutron shielding filaments, such as Boron Carbide and Gadolinium Oxide filaments. When using traditional 3D model slicer software, the user is at the mercy of the slicer algorithm to determine the printhead path routing, which can leave scarring across the delicate printed object. This talk will demonstrate a strategy used to create optimised and deliberate printhead path routing which results in collimator geometry with defect free internal channels.

To make something new out of the old (Mechanical structures)

• Benjamin Giroud (ILL)

Following the Fukushima accident, all nuclear and sensitive facilities have had to address new requirements. One of the most challenging issues is ensuring that all facilities can withstand earthquake intensities previously unimaginable. Like power plants, the ILL is required to ensure that all safety equipment can withstand an “SND” earthquake with an intensity twice that of the region’s most powerful earthquake in the past 1,000 years. Numerous backup systems and reinforcements have been implemented since then, and the latest safety systems are currently being modified to bring the facility into compliance with the new safety standards. I am in charge of the latest work on the casemates and will attempt to give a presentation highlighting the challenges of bringing an old facility into compliance with the latest regulatory requirements.

Post-HBRR Common Vacuum Housing Shielding on HB4 at the High Flux Isotope Reactor (Shielding)

• Kyle Grammer (Oak Ridge National Laboratory)

The High Flux Isotope Reactor at Oak Ridge National Laboratory is plan- ning the replacement of the permanent beryllium reflector. During this outage, all of the cold guide hall instruments will be removed and reinstalled with new supermirror guides, vacuum casings, and modifications/replacement of some ex- isting shielding. The new Cold Guide Hall guide network will have six primary neutron beamlines rather than the current four, which presents challenges due to limited spacing of the neutron beamlines. Additionally, streaming of neutrons and gammas through the vacuum network into the cold guide hall must be mit- igated for personnel dose reasons. The current status of the planned vacuum network through the HB4 tunnel and shielding updates will be discussed.

Generation of correlated surface source distributions for Monte Carlo shielding calculations (Shielding)

• Santiago Bazzana (Comisión Nacional de Energía Atómica, Instituto Dan Beninson (UNSAM))

The design of shielding for neutron instruments often requires the reactor model to be decoupled from the instrument model, allowing multiple calculations to be performed without transporting particles from the reactor core during every design iteration. This approach requires an accurate and efficient representation of the neutron and photon fields at the interface between both models. MCNP provides different approaches for transferring particle distributions between independent calculations. Surface source files (SSR/SSW) preserve complete particle histories but may become impractical when high spatial, energy and angular resolution is required because of the large file sizes involved. Alternatively, source distributions can be reconstructed from surface current tallies and implemented through the SDEF card. However, this approach requires extensive data processing and cannot fully reproduce the angular phase space, since arbitrary azimuthal distributions relative to the local surface normal cannot be represented. Custom MCNP user routines based on tallyx and sourcex were developed to record and sample discretized surface source distributions directly within the transport code. The source is represented by a set of conditional probability distributions for the spatial, energy and angular variables of the particle phase space. This formulation preserves the correlations between position, energy and direction, including the azimuthal angle. The proposed methodology is tested against conventional track-based sources and SDEF-generated source distributions. Neutron and photon flux distributions evaluated along the instrument axis in several energy groups are used to compare the results obtained with the three source representations. The comparison is performed for the ASTOR and ANDES neutron instruments of the Argentine Neutron Beam Laboratory (LAHN).

Post-Endurance instruments projects at the ILL (Instrument design and construction)

• Giuliana Manzin (Institut Laue Langevin)

The ENDURANCE program at the ILL lasted several years and ended in 2024. It allowed the renovation of two major neutron distribution guides and the design and installation of several instruments. Despite this recent milestone, a constant stream of modernization ideas and upgrades have shown once more that in order to consolidate existing strenghts and to adapt to new societal challenges a constant evolution is the key. The most recent examples of new instrument designs are going to be presented.

Moderator Test Station at the Spallation Neutron Source: Final Design, Project Lessons Learned, and Path to Operations (Instrument design and construction)

• Kevin Johns (Oak Ridge National Laboratory)

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory currently operates up to 2 MW and 1.3 GeV at the First Targe Station. With the power increase from the Proton Power Upgrade project realized, future performance improvements will increasingly depend on advances beyond the accelerator, including optimization and novel developments in moderator design and operation. The future Second Target Station, also located at SNS, will establish a new benchmark for moderator brightness at a short-pulse neutron facility. Together, the two target stations will provide complementary capabilities that expand the scientific reach of the SNS user program. Moderators are often cryogenic, hydrogenous vessels positioned adjacent to neutron-producing targets that tailor neutron energy distributions for the instrument suites they serve. Many moderators also incorporate neutron poisons, such as cadmium or gadolinium, to further shape the temporal characteristics of the neutron pulse. Moderator geometry, materials, operating media, and thermal conditions all have a significant influence on the brightness, pulse shape, and overall performance of the neutron beam delivered to scientific instruments. At SNS, moderators are integrated within the Inner Reflector Plug (IRP), a complex assembly that is typically replaced only once every five years. The development, qualification, and integration of updated moderator designs begin many years before installation, leaving limited opportunities to validate new concepts under representative operating conditions. Because moderator performance cannot be readily adjusted after installation, reducing technical risk through prototype testing is essential. The Moderator Test Station (MTS) at SNS is being developed to provide a dedicated platform for the evaluation and optimization of next-generation moderator technologies. Numerous promising moderator concepts have the potential to significantly improve neutron brightness and pulse characteristics but require experimental validation prior to deployment in an operating target station. By providing an on-site test facility, MTS will accelerate the maturation of new moderator designs for both the First and Second Target Stations while reducing implementation risk. The MTS project has completed final design, including supporting development activities, and has entered the procurement phase. This presentation will provide an overview of the completed design, summarize the key development and testing efforts that informed it, along with lessons learned, and discuss the upcoming installation activities that will enable accelerated development of future moderator technologies at SNS.

Development and implementation of neutron instruments in RA-10 Reactor (Project management)

• Martín González Fuster (Comision Nacional de Energia Atomica)

LAHN (Argentine Neutron Beam Laboratory Research Centre) is currently working on the development and implementation of neutron instruments, with a range of characteristics and applications, which will be installed at the RA-10 facility. On the one hand, ANDES (Advanced Diffractometer for Engineering and Science) and ASTOR (Advanced System for Tomography and Radiography) instruments, which are being developed from the concept stage through to operation and will be installed in the Reactor hall. Moreover, on the other hand, the polarised neutron reflectometer, the SANS MP (Small-angle Neutron Scattering – Multi-purpose) and the SANS MB (Small-angle Neutron Scattering – Soft Matter), which originate from other international facilities and will be adapted and installed in the reactor’s guide hall. Development and implementation of the aforementioned instruments require the planning, coordination and execution of various activities (calculation, design, specification, procurement, manufacture, assembly, commissioning) and involve interdisciplinary working groups from different technical fields (mechanics, shielding, automation and control, optics, etc.) which address issues specific to the instruments as well as others that may be cross-cutting. Furthermore, many of the components that make up the instruments are highly sophisticated due to the performance required by their design and their functionality under adverse radiological conditions. Component development strategies vary and depend largely on the capabilities, resources and timeframes available within the institution to address them. Currently, the detailed engineering of the instrument components is nearing completion, and the critical components are already at the manufacturing stage. These highly complex projects represent a scientific and technological challenge for the institution and, given their current stage of development, it is expected that their implementation will make a significant contribution to research and development in the nuclear field.

ORNL HFIR Cold Triple Axis Drum Reuse for MANTA (Instrument design and construction)

• Greg Warren (ORNL)

Multi Analyzer Neutron Triple Axis (MANTA) is a proposed instrument for The High Flux Isotope Reactor (HFIR) on NB-6 beamline of the enhanced multiple guide system planned for the next HFIR Beryllium Reflector Replacement (HBRR). The instrument will reuse the CG-4C Cold Source Triple Axis (CTAX) drum and backend. This permits use of existing conventional Sample Environment Equipment (SE) and SE upgrades.

Development and implementation of ASTOR instruments in RA-10 Reactor (Instrument design and construction)

• Alejandro Fasciszewski (CNEA)

The LAHN is currently working on the development and implementation of neutron instruments, with a range of characteristics and applications, which will be installed at the RA-10 facility, ASTOR (Advanced System for Tomography and Radiography) instruments, which are being developed from the concept stage through to operation and will be installed in the reactor hall, require the planning, coordination and execution of various activities (calculation, design, specification, procurement, manufacture, assembly, commissioning) and involve interdisciplinary working groups from different technical fields (mechanics, shielding, automation and control, optics, etc.). The presentation summarizes the progress status of the ASTOR Project, addressing the main technical and management workstreams. It outlines the evolution of the project's overall schedule, including the update of milestones and the planning of critical activities. It also presents the progress in the assembly and alignment of the primary collimator, the verifications carried out to ensure compliance with the design tolerances, and the preparatory tasks for its integration with the instrument. It also reports the development status of the collimator drum, covering the basic engineering and the procurement process for its manufacturing and supply. Regarding the bunker, it describes the progress in the design and manufacturing of its main components, the progress of the cold assembly to validate interfaces, alignments, tolerances, and assembly sequences, and the planning of the final assembly in the Hall, including the considerations for future maintenance and disassembly tasks. Taken together, these advances help reduce risks during the final installation and ensure the proper integration of the ASTOR system into the LAHN.

LoKI’s Transition to Operations: Commissioning, Upgrades, and Operational Readiness of ESS’s First SANS Instrument (Project management)

• Hannah Burrall (European Spallation Source, 224 84 Lund, Sweden)

LoKI, a small-angle neutron scattering (SANS) instrument, is one of the first instruments to come online at the European Spallation Source (ESS). The instrument recently passed Toll-Gate 5 (TG5), a major milestone marking the completion of the instrument System Acceptance Review (SAR) and Safety Readiness Review (iSRR). This milestone represents LoKI’s transition from construction and cold commissioning toward operation. Since achieving TG5 in early 2026, significant effort has been focused on preparing LoKI for operations through continued instrument commissioning, system upgrades, automation development, and establishment of operational processes. This contribution highlights recent activities undertaken to support operational readiness, including completion of the detector upgrade project, commissioning of sample environment systems, validation of data acquisition and processing pipelines, and development of standardized measurement and maintenance scripts. In addition to technical commissioning activities, preparation for operations has included the development of operation and maintenance procedures, shutdown and startup sequences, maintenance tracking strategies, spare parts management, and improvements to supporting infrastructure such as sample storage and operational documentation. This talk provides an overview of the recent activities undertaken to prepare LoKI for reliable user operation and presents the planned work for the remainder of the year in preparation for Beam on Target (BoT).

EPICS-Based Sample Environment, Data Acquisition, and Controls Across Spallation Neutron Source Beamlines (Control systems)

• Mariano Ruiz (Oak Ridge National Laboratory)

All Spallation Neutron Source beamlines use the Experimental Physics and Industrial Control System (EPICS) for sample-environment control, data acquisition, and experiment automation. The Beamline Instrument Data Acquisition and Controls Group supports several sample-environment teams focused on low- and ultra-low-temperature systems and magnets; soft matter; automation and robotics; high-pressure and gas systems; and high-temperature furnaces and sample levitation. To interface with sample-environment equipment, we support hardware connections and communication protocols including EtherNet/IP for programmable logic controllers, Modbus, PROFIBUS, text-based TCP/IP, Standard Commands for Programmable Instruments (SCPI), JSON, MQTT, LabVIEW-based systems, and direct analog and digital control. This flexibility allows commercial, in-house custom-built, legacy, and PLC-controlled equipment to be integrated into a common EPICS architecture. Controlled equipment includes magnets of various sizes and operating ranges, including a 14-tesla uncompensated magnet; ultra-low-temperature systems, including dilution refrigerators reaching 30 mK and cryostats; high-temperature furnaces reaching 1,600 °C; rheometers, ultrasonic systems, and high-performance liquid chromatography pumps; high-pressure systems operating up to 70,000 psi; and high-voltage systems operating up to 10 kV. Other examples include gas-mixing systems that combine gases at controlled ratios and flow rates, pneumatic and electrostatic levitators, and robotic arms for automated sample handling, liquid pipetting, and mixing. The control workflow begins with an EPICS input/output controller that communicates with the hardware and publishes read and write process variables through Channel Access on the protected instrument network. CSS/Phoebus graphical interfaces allow users and instrument staff to monitor status, modify operating parameters, and control equipment. EPICS access security determines who may write to restricted process variables. Important sample-environment process variables are archived at configured sampling rates and tolerances and retained indefinitely, providing a long-term record of experimental conditions and equipment performance. EPICS autosave stores setpoints locally so they can be restored after an IOC restart. Selected process-variable values are embedded in the final experimental run file for analysis alongside the neutron-scattering data. Alarm conditions can also generate notifications for Instrument Hall Coordinators, providing continuous operational coverage. Users automate experiments through Scan Server scripting, CSS/Phoebus table scans, and Python scripts. These tools coordinate devices and modify process variables according to predefined sequences or conditions determined by beam exposure time, accumulated proton charge, neutron counts, equipment status, or data from other subsystems. At selected beamlines, authorized users can also securely submit AI-driven experimental sequences from a separate internal network, including workflows for an AI-enabled pipetting robot. This architecture unifies hardware communication, graphical interfaces, access security, archiving, alarms, experiment metadata, and automated execution within EPICS.

Integrated Design for Neutron Instrument Shutter Control: Fail Safe Hardware and PLC Programming Best Practices (Control systems)

• Jorgen Miller (NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA)

At scientific neutron source facilities, instrument shutter systems are the primary mechanism for beam control at an instrument. Given the criticality of these systems, they must be engineered for safety for hazard control, high reliability to minimize scientific downtime, and maintainability across a large fleet of instruments. This presentation details the best practices developed at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) for the integrated design of instrument shutter control systems. On the hardware front, the discussion examines the selection of Programmable Logic Controllers (PLCs) versus custom circuitry, the importance of placement of system components, and the implementation of fail-safe wiring, such as the use of normally closed (NC) circuits for interlocks to ensure positive state determination. Special emphasis is placed on indicate-safe signage, ensuring that a single electrical failure cannot falsely indicate a safe condition. From a software perspective, the work outlines standardized PLC programming patterns designed to eliminate common failure modes. This includes techniques from latch/unlatch logic to state machines and step-complete architectures. Input and output (IO) mapping and abstraction are suggested as well as heavy use of internal variables. Furthermore, the human-machine controls are addressed, focusing on the ergonomics of control placement and the psychological impact of signage and alarms. The work advocates for consideration of color associations, text pairing, and accessibility. Finally, this work presents lessons learned based on failure modes encountered at the NCNR. By synthesizing these experiences into a set of design standards, this presentation provides a roadmap for developing instrument shutter control systems that are safe, reliable, and maintainable to minimize human and system error.

State-Based Automation of the Monochromator Shielding Device for the ANDES Neutron Diffractometer (Control systems)

• Fernando Burgos (CNEA)

ANDES is a neutron diffraction instrument for materials characterization currently under development by the Argentine National Atomic Energy Commission (CNEA) as part of the Argentine Laboratory of Neutron Beams (LAHN) project. One of its key mechanical subsystems, SS03, is responsible for selecting the neutron energy spectrum and orienting the neutron beam by positioning the monochromator assembly. The subsystem comprises two electromechanical devices, including the **Monochromator Shielding Device**, whose operation requires coordinated motion, fault supervision, and safe interaction between pneumatic and electromechanical actuators. The development of the automation system for the Monochromator Shielding Device goes from the conceptual design to its implementation and experimental validation. The development included the definition of the control architecture, hardware and software selection, PLC programming, virtual commissioning through simulation, and commissioning of the physical machine. This works presents the methodology adopted to develop the automation system. The controller was implemented as a **hierarchical finite state machine (HFSM)** in accordance with the **IEC 61131-3** standard and organizes the machine behavior into two operating principal modes: **User Mode** and **Maintenance Mode**. User Mode supports the normal operation of the neutron instrument, whereas Maintenance Mode manages machine initialization, homing, calibration, diagnostics, and recovery from abnormal conditions. State transitions are determined by sensor feedback, operator commands, and safety conditions, allowing the controller to respond predictably while maintaining safe machine operation. The HFSM architecture also simplifies the implementation of fault recovery procedures and facilitates future software maintenance and functional expansion. The controller integrates digital and analog inputs from the machine instrumentation to coordinate two primary actuators: a pneumatic cylinder driven by a proportional 5/3 directional valve and a closed-loop stepper motor that positions the rotating shielding assembly. The implemented logic supervises the complete operational sequence, validates machine states before every motion command, and continuously monitors the process to detect unsafe or unexpected operating conditions. The proposed automation architecture provides a reliable and maintainable control solution for the Monochromator Shielding Device. The methodology developed for SS03 can be extended to other mechatronic subsystems requiring coordinated motion, state-based supervision, and high operational reliability in large scientific instrumentation facilities.

Frontiers of Artificial Intelligence: From Automation in Scientific Instrumentation to Predictive Safety (Data management (Software, AI))

• Leonardo Ibáñez (CNEA)

The integration of Artificial Intelligence (AI) in the nuclear sector ranges from the optimization of scientific instruments and their auxiliary systems to the strengthening of operational safety in reactors. This work presents advances in the development of artificial intelligence models applied to two critical areas: neutron control and instrumentation through synthetic training, and reactor safety diagnostics based on real-world data. In the first line of research, Artificial Neural Networks (ANNs) were designed for a polarized neutron reflectometer with multiple operating modes and for a gas delivery system used as an autonomous sample environment equipment (SEE). Due to the lack of historical records, physical simulation environments were developed to generate synthetic training data. In the SEE, the ANNs perform the automatic operation of flows and pressures, suggest optimal configurations, and run simulations, offering a modular design transferable to other industries. In the reflectometer, the networks assist in the dynamic optimization of the instrument and the analysis of complex experimental data. The second line of research focuses on nuclear safety through the application of ANN for the analysis of digitized sensor signals from real reactor data. Here, these neural networks are deployed to solve shutdown classification tasks (distinguishing between controlled and abnormal events) and for time-series forecasting. Unlike the simulation-based approach, this direct application of ANN to real operating data faces two fundamental challenges in the sector: the extreme scarcity of data associated with failures or anomalies and the imperative need for model interpretability to ensure auditable and safe decision-making. In conclusion, these developments, currently in the design and testing phase, demonstrate the versatility of AI to adapt to diverse scenarios and requirements within the nuclear sector. The ability to transition effectively from the automation and simulation of scientific instrumentation to predictive diagnostics in reactors consolidates AI as a transversal and scalable technology, capable of providing solutions both in frontier experimental research and in the critical operation of safety systems.

Boosting Scientific Value Through Instrument Relocation (Project management)

• Gabriela Aurelio (Nuclear Business Development - INVAP S.A.U.)

The Argentine Neutron Beam Laboratory (LAHN), currently under development at the National Atomic Energy Commission (CNEA), will provide the national and regional scientific community with access to neutron scattering techniques for research in materials science, engineering, biology, and several other disciplines. A key element for developing the initial instrument suite has been the transfer of neutron instruments and infrastructure components from leading European neutron facilities through international cooperation agreements. The opportunity for these transfers emerged largely following the shutdown of the BER II research reactor at Helmholtz-Zentrum Berlin (HZB) on December 2019, which triggered a broader process within the international neutron-science community to reallocate and preserve valuable instrumentation and infrastructure for continued scientific use. Within this context, LAHN identified a unique opportunity to accelerate the development of its future instrument suite through the reuse of proven equipment from established facilities. The transferred equipment includes a neutron reflectometer, a Small-Angle Neutron Scattering (SANS) multipurpose instrument, and part of the neutron guide system donated by HZB (Germany), as well as a SANS instrument dedicated to soft matter research donated by the Paul Scherrer Institute (PSI, Switzerland). These transfers involved the relocation of large-scale scientific assets, requiring close coordination among research institutions, governmental agencies, customs authorities, logistics providers, and technical specialists in multiple countries. This presentation reviews the complete transfer process, including instrument assessment and selection, negotiation of donation agreements, preparation for decommissioning and dismantling, export and import procedures, transportation logistics, and final reception in Argentina. Particular attention is given to challenges related to regulatory and administrative requirements associated with the international movement of irradiated equipment, as well as those encountered during customs clearance, documentation management, and cross-border transport. The experience generated several valuable lessons regarding planning, stakeholder engagement, regulatory coordination, risk mitigation, and the preservation of technical knowledge associated with transferred instruments. These lessons may be relevant for other facilities facing similar opportunities to relocate scientific infrastructure and maximize the long-term value of existing neutron instrumentation.

Status of the SNS Second Target Station Project at Oak Ridge National Laboratory (Project management)

• David Anderson (Oak Ridge National Laboratoryl)

The Oak Ridge National Laboratory (ORNL) Second Target Station (STS) Project is a 10+ year, multi-billion (US) dollar project to build a second target station at ORNL’s Spallation Neutron Source (SNS). The STS will deliver a 700 kW, 15 Hz proton beam to a solid tungsten rotating target, producing neutrons for up to 21 neutron scattering instrument end stations. The STS will provide the highest peak brightness cold neutrons in the world. The science capabilities provided by the instrument suite at the STS will complement those of the two existing neutron scattering user facilities at ORNL, the SNS First Target Station (FTS) and the High Flux Isotope Reactor (HFIR). This talk will discuss the status of the project, which completed its most important reviews to-date this year. A brief technical overview update of the Project and its 5 major technical subsystems will be given, including a 3-1/2 minute animated flythrough of the Top-Level Master CAD model. Site preparation progress will be reported, and an update on user community selection of the initial Instrument Suite will be provided. The ORNL Second Target Station Project is funded by the US Department of Energy Office of Science Basic Energy Sciences program.

Twenty Years of Operating Neutron Instruments at the OPAL Reactor in Sydney (Project management)

• Scott Olsen (Australian Nuclear Science and Technology Organisation)

The OPAL reactor achieved first criticality in August 2006. The initial suite of neutron scattering instruments commenced routine user operations during 2007–2008, followed by a second suite commissioned between 2013 and 2014. Today, 14 instruments are in operation, supported by a reactor schedule of approximately 300 operating days per year. As the reactor celebrates its 20th anniversary, a number of significant upgrade and asset renewal projects have been undertaken. These include the complete rebuild of a Laue diffractometer, based on the Institut Laue-Langevin (ILL) design, between 2022 and 2025. In addition, the instrument safety interlock system is being replaced to address component obsolescence, while neutron guide replacements and extensions have been implemented on several instruments over the past five years to enhance performance and capability. The project management framework employed at ANSTO has evolved considerably over the past two decades. A notable recent change has been the introduction of staged funding approvals, whereby project funding is released progressively through stage-gate reviews rather than being committed across the entire project lifecycle at inception. This approach has strengthened governance, oversight, and risk management. The two major instrument construction programs used a program management model, with multiple projects led by dedicated project managers. Early teams typically comprised a scientist, mechanical technician and drafting support, backed by shared engineering expertise in detectors, software, electronics, controls, electrical systems and mechanical engineering. A key challenge in an operating research facility is balancing new instrument and sample environment capabilities against maintenance and replacement of ageing assets. This requires long-term asset planning, lifecycle management and responsiveness to user needs. Instrument group leaders and engineering management review and rank competing upgrade, maintenance and replacement priorities annually. Instrument upgrade projects now incorporate operational dose data into MCNP models, improving predictions of shielding and safety requirements. Engagement with the DENIM and ISNIE communities has reduced development effort and project risk, recently , for example, expertise from STFC ISIS and ORNL SNS has informed ANSTO on our recent neutron Fermi chopper upgrade plans.

Engineering Better Neutron Instruments through Structured Project Management (Project management)

• Tania Claudio Weber (Forschungszentrum Jülich GmbH)

The construction of modern neutron scattering instruments has evolved into a multidisciplinary engineering challenge requiring the coordinated efforts of scientists, engineers, technicians, industrial partners and international research organizations. As projects increase in technical complexity, the application of structured project management methodologies becomes as important as the engineering itself. This presentation summarizes practical project management lessons learned during the development of neutron instruments at Forschungszentrum Jülich (FZJ) for the European Spallation Source (ESS), using the PMBOK® Guide as an overarching framework while adapting established engineering and cost-estimation practices to the specific needs of large scientific infrastructure projects. The presentation follows the complete project lifecycle. Particular attention is given to the importance of investing sufficient effort in project planning, demonstrating how thorough preparation substantially reduces technical and organizational risks during execution. A Systems Engineering V-model is proposed as the backbone for developing a coherent Work Breakdown Structure (WBS), ensuring full traceability from scientific requirements to verification and commissioning activities. Cost estimation is addressed through an adaptation of the AACE Cost Estimate Classification System specifically tailored for neutron instrument projects, enabling estimates of increasing maturity to be aligned with project phases and decision gates. For monitoring and controlling, the presentation discusses the practical application and limitations of traditional earned value metrics such as the Schedule Performance Index (SPI), Estimate at Completion (EAC) and Estimate to Complete (ETC), together with complementary indicators better suited to highly technical research and engineering projects where technical readiness, interface maturity and risk evolution often provide earlier warning than schedule metrics alone. Finally, the importance of project closure is highlighted. Successful projects do not end with technical acceptance but with comprehensive documentation, structured knowledge transfer and effective communication of lessons learned, ensuring that future neutron instrument projects benefit from accumulated experience rather than repeating previous challenges.

Mechanical Design Verification of the ANDES Instrument Using Metrology and Performance Testing (Instrument design and construction)

• Fernando Burgos (CNEA)

ANDES is a neutron diffraction instrument for materials characterization being developed by the Argentine National Atomic Energy Commission (CNEA) within the Argentine Laboratory of Neutron Beam(LAHN) project. Subsystem SS03 is responsible for orienting the neutron beam and selecting the incident neutron energy by positioning one of three monochromators within the beamline. Owing to the demanding requirements for positioning accuracy, repeatability, and mechanical stability, the subsystem was designed as two independent electromechanical machines. The first machine, the **Monochromator Shielding System** (_Blindaje de Monocromadores_), is a two-axis mechanism that selects and positions one of two 320 kg neutron shielding blocks through vertical translation and rotary motion. Vertical displacement is provided by a pneumatic actuator, whereas rotational positioning is achieved through a four-stage gear transmission driven by a closed-loop stepper motor. The second machine, the **Monochromator Exchange System** (_Sistema de Intercambio de Monocromadores_), is an eight-axis positioning system composed of three horizontal linear stages, one vertical linear stage, one rotary stage, and three circular-segment stages. This mechanism accurately positions and orients three neutron monochromators to direct the diffracted beam according to the experimental configuration. During operation, the selected monochromator is positioned through the coordinated motion of the corresponding horizontal stage together with the vertical, rotary, and circular-segment axes. This work presents the verification methodology adopted during the development of SS03, combining mechanical metrology, tolerance analysis, manufacturing and assembly validation, and functional performance testing. For the Monochromator Exchange System, position repeatability tests were performed on the three horizontal linear stages to validate the positioning strategy and identify opportunities for design refinement. For the Monochromator Shielding System, the verification process focused on achieving a positioning resolution better than 0.5 mm. The evaluation included geometric inspections of the rotating assembly, including flatness and parallelism runout measurements, as well as characterization of the gear transmission, with particular attention to the pitch diameter runout of the large driven gear. The overall positioning performance was assessed through cyclic accuracy and repeatability tests. The experimental results are presented and discussed together with the design modifications implemented to improve the subsystem performance. The proposed verification methodology demonstrates the importance of integrating metrology, tolerance control, and experimental validation throughout the design process of precision mechatronic systems for neutron instrumentation, providing a systematic approach for achieving the positioning performance required by large-scale scientific facilities.

Metrology in the Assembly of LAHN: Tolerance Analysis for Neutron Beams HAZF1 and HAZT1 Characterization (Instrument design and construction)

• Ezequiel Anacoreto (CNEA)

In the development of instruments for neutron beam techniques, leveraging available state-of-the-art metrology tools is essential. The primary objective is to accurately determine the geolocation of neutron beams originating from the RA-10 reactor to ensure proper installation and periodic surveying of the LAHN instrumentation. The Laser Tracker technique stands out as a portable, high-precision, and rapid measurement solution. To maximize its performance, it is necessary to design and implement a suitable measurement strategy that allows the acquired data to be effectively utilized across the various teams involved in field operations. This paper presents the measurement strategy employed for the spatial characterization of the HAZF1 and HAZT1 beamlines for the ASTOR and ANDES instruments, using the embedded boxes in the RA-10 facility’s Reactor Hall as spatial references. Point cloud maps were generated, error types were evaluated, and reference locations were established for future integration tasks.

Precision Positioning Systems for ANDES Diffractometer (Instrument design and construction)

• Santiago Javier Pincin (Comisión Nacional de Energía Atómica - Instituto Balseiro)

The ANDES diffractometer requires highly precise movement of its neutron components to function optimally. To meet these stringent requirements, we established a comprehensive pipeline to design, manufacture, mount, integrate, and test precision linear positioning systems. This paper describes the development and implementation of six specialized systems. First, a compact dual-axis (< ∅ 150 × 50 mm) XY linear stage was developed for sample oscillation. Second, a monochromatic beam optics system was designed, incorporating three linear stages for prismatic slit positioning. Third, an 8-Degree-of-Freedom (DOF) monochromator interchange system was engineered and partially tested; it features two custom, in-house linear stages providing 800 mm of vertical travel and 50 mm of horizontal movement. Fourth, a novel 2-DOF oscillating collimator was implemented, combining lateral linear and rotational movements to simplify center calibration and enable standard oscillation. Fifth, a modular prismatic slit was developed using additive manufacturing for prototyping, featuring independent blade mechanisms with integrated internal cable routing and minimized backlash. Finally, a standard 4-DOF neutron slit system was designed (two window sizes (150 × 150 mm and 300 × 300 mm)), built, and partially tested, controlled via a custom 4-stepper-motor box using G-code commands over USB serial. This work outlines the developed institutional capacities and discusses critical engineering challenges, including engineering documentation, manufacturing tolerances, operational requirements, and testing methodologies.

Development of in-kind / in-house built 130 m long neutron transport beamline (Mechanical structures)

• Fernando Yamil Moreira (European Spallation Source ESS ERIC)

CSPEC is a cold chopper spectrometer to come operative at the end of 2027. This beamline is unique at ESS as the transport system was developed in-house as an in-kind contribution from TUM/LLB and not procured from one of the known commercial suppliers for this kind of system. We will present the mechanical design of supports, vacuum housing, neutron guides and its integration with the active components of the transport system, i.e. choppers, shutters, monitors, shielding. A qualitative evaluation of this construction approach will be presented, along with the challenges and advantages encountered.

FermiChopper NECTAR (TUM FRM2) (Turning machines (choppers, NVS))

• Rudolf Schütz (TUM FRM2 (MLZ))

In the past years, the instrument NECTAR has been rebuilt from the ground up with many upgrades for thermal neutrons. Continuing in these foot¬steps, NECTAR will further enhance its capabilities for H-quantification and phase mapping via energy-resolved neutron imaging. This will be achieved using a unique and compact chopper design. At its core, the chopper consists of a 100 mm diameter 3D printed boron-containing PLA insert that rotates around its cylindrical axis and contains an array of 684 channels, each measuring 1 × 1 mm². Costs of a portable chopper less than 10,000 Euros (material, machining and electronics). The talk is about the development of the Chopper, its problems of the prototypes and changes.

Challenges during the upgrade of a Neutron Velocity Selector (Turning machines (choppers, NVS))

• Zsolt Ludanyi (Mirrotron Ltd.)

Monochromatic neutron beams are essential for most neutron scattering experiments and can be produced using crystal monochromators, the time-of-flight (ToF) method, or neutron velocity selectors (NVS). While crystal monochromators and ToF techniques provide superior wavelength resolution, neutron velocity selectors offer high neutron transmission and widely variable wavelength range, making them indispensable for many neutron instruments, especially in the long wavelength range, where Bragg-crystals are limited. A neutron velocity selector consists of a rotating drum with helical slits coated with a neutron-absorbing material, typically Boron-10 or Gadolinium. The helical geometry transmits only neutrons within a selected velocity range while absorbing neutrons of other velocities. Mirrotron Ltd’s original mechanical neutron velocity selectors were first developed at the KFKI research centre (now Budapest Neutron Centre). The first multidisc (MDR) design, patented in 1988, represented a major breakthrough by replacing conventional heavy drum selectors with a lightweight multidisc structure, enabling significantly improved performance. Following a technology transfer in 1992, Mirrotron began manufacturing and distributing these selectors. In the past 30 years several improvements of the parameters and various technical solutions have been made. Between 2022 and 2024, Mirrotron completed a comprehensive major redesign of both the mechanical and electrical systems. The development required overcoming several manufacturing challenges, implementation of modern manufacturing technologies, optimization of assembly procedures, and the qualification of a reliable Boron-10 coating process. The upgraded design delivers a wider selectable neutron wavelength range through an increased maximum rotation speed, reduced maintenance requirements with keeping the long operational lifetime. This presentation reviews the history of this unique device and compares its original and upgraded designs. It discusses the motivation for the redesign, the principal engineering and manufacturing challenges encountered during development, the implemented design solutions, and the performance of the upgraded neutron velocity selector.

Return to Science at the NIST Center for Neutron Research (Project management)

• Daniel Adler (NIST)

The NIST Center for Neutron Research (NCNR) is returning to scientific operations following an extended outage initiated in January 2021 due to a damaged reactor fuel element. An extensive cleanup effort in 2022 established safe operating conditions within regulatory limits, however, routine operations were inhibited by a small quantity of damaged element debris (~1-3 g) still present in the reactor vessel after the initial cleanup. In 2024 the NCNR kicked off a new project to disassemble the vessel for further cleaning ahead of a return to scientific operations. Concurrent with this reactor recovery project, the facility has executed major upgrades to its three oldest cold neutron guide lines (NG-5, NG-6, and NG-7) and the associated guide support systems. Replacing legacy optics with modern supermirrors and optimized guide geometries will improve data rates by a factor of 2-10 for the nine instruments served by these guide lines. This presentation will detail the key engineering and design challenges associated with the reactor recovery and guide line upgrade projects and will discuss the return to scientific operations and beyond at the NCNR.

Preparing the FRM II Instrument Suite for Reactor Restart: A Framework for Readiness Assessment (Project management)

• Aureliano Tartaglione (MLZ - TUM (FRM II))

The FRM II research reactor has been shut down since March 2020 due to a series of technical issues. Initially, the cold neutron source was found to be defective and subsequently removed. Later, inspections identified problems with the reactor's central channel, which must be replaced before operations can resume. According to the current project schedule, the replacement is planned for 2027. To ensure a successful restart, the entire FRM II instrument suite must be ready when reactor operations resume. However, the status of the 36 instruments varies considerably. While many instruments were fully operational during the last reactor cycle, several have undergone upgrades of varying scope during the shutdown period, and eight instruments are entirely new installations. In January 2026, our team was tasked with collecting first-hand information from the instrument responsible scientists and the central technical groups to provide MLZ management with a comprehensive overview of the readiness of the instrument suite. The objective was to support strategic decision-making and optimize the allocation of limited resources, maximizing the number of reliable instruments available for the first user cycle following the reactor restart. This contribution presents the methodology developed to assess instrument readiness, coordinate information from multiple stakeholders, and support management decisions. It also discusses the key challenges encountered and the lessons learned during this process, which may be relevant for the restart planning of other large-scale scientific facilities following extended shutdowns.

The Argentine Neutron Beam Laboratory: Historical Evolution, Current Status, and Future Perspectives

• Karina Pierpauli (CNEA)

The Argentine Neutron Beam Laboratory (LAHN) represents a landmark initiative designed to coordinate a world-class national facility for advanced neutron scattering techniques. As the first large-scale experimental neutron facility in Latin America, LAHN bridges the regional gap in "Big Science" infrastructure. This summary outlines the genesis of the project, its current implementation milestones, and the strategic roadmaps designed to overcome logistical, financial, and human resource challenges. Historically, world-class neutron scattering facilities—which require high-flux nuclear research reactors or large particle accelerators—have been heavily concentrated in the Northern Hemisphere. This technological disparity restricted Latin American researchers to short-term, competitive experiments abroad. To address this, the project was conceptualized to leverage the construction of the RA-10 Multipurpose Argentine Reactor. Initiated with strategic planning in 2016, early efforts focused on assessing regional demand. A pivotal 2017 workshop co-organized by CNEA and MinCyT established the "Scientific Cases" framework, documenting specific research needs across 28 participating institutions, 63 research lines, and multiple countries in the region. These metrics directly dictated the initial instrumentation suite design. LAHN is currently transitioning from a conceptual framework into a physical reality at the Ezeiza Atomic Center. Reactor Infrastructure: The RA-10 reactor, which provides the high-flux neutron source, has surpassed 95% construction completion. Its flux capacity will be fully competitive with leading international facilities like MLZ (Germany), and ACNS (Australia). Core Team: More than 60 professionals and researchers within CNEA are actively collaborating on the design, development, and management of the facility. International Cooperation: Strong partnerships have led to the acquisition of valuable instrumentation. Notably, the Helmholtz Zentrum Berlin (HZB) has donated a multipurpose SANS instrument and a polarized neutron reflectometer. Additionally, the Paul Scherrer Institut (PSI) in Switzerland has donated a dedicated SANS instrument for soft matter studies. Community Engagement: The center has established a network of over 1,000 connected researchers, trained more than 300 individuals through annual ETNA schools, and hosted five biennial Argentine Neutron Techniques Congresses. To achieve full operational capability as a 24/7 open-access National Laboratory, LAHN must systematically address some critical challenges: Formal cross-institutional agreements within the Argentine Scientific-Technological System must be established. This ensures collective responsibility for the operation, maintenance, and open-access beamtime allocation. While the facility can accommodate approximately 14 instruments, the immediate hurdle is securing sustained funding to relocate, install, and optimize the donated instruments, alongside funding the native CNEA developments (Neutron Imaging and Engineering Diffractometer, etc). The current workforce of ~50 personnel must scale up to a permanent staff of 80 professional. Recruiting and retaining specialized "Instrument Scientists" who lead the technical and scientific evolution of each beamline remains vital.