Pulsed Neutron Source and the Complex of Spectrometers

Participating countries and international organizations:

Argentina, Armenia, Azerbaijan, Belarus, Bulgaria, China, Cuba, Czech Republic, Egypt, France, Germany, Hungary, IAEA, India, Italy, Japan, Kazakhstan, Latvia, Mongolia, Poland, Romania, Russia, Serbia, Slovakia, South Africa, Spain, Sweden, Switzerland, Tajikistan, USA, Uzbekistan, Vietnam.

The problem under study and the main purpose of the research:

Revealing the relationships between the structural features of materials and their physical properties at the microscopic level is one of the fundamental tasks that determine the development of modern concepts in the field of condensed matter physics, materials science, chemistry, geophysics, engineering, biology and pharmacology. The unique advantages of using neutron research methods make their application the most optimal, and in some cases the only approach for solving a wide range of topical fundamental and applied problems. For the successful implementation of the neutron research program, it is of utmost importance to support and develop large infrastructures, encompassing the neutron source and the suite of spectrometers.

The main task of the project for the development of the existing neutron source is to increase the efficiency in the use of the
IBR-2 research nuclear facility for implementation of the program of experimental investigations, to ensure operational reliability and safety of the reactor. Regular operation of the IBR-2 research nuclear facility is carried out in accordance with the Rostekhnadzor license with an average power of up to 2 MW. The IBR-2 facility is equipped with modern safety control systems, systems of analysis and diagnostics of the reactor state, systems for radiation monitoring and control of radiation situation.

The main objective of the project for the development of the complex of spectrometers is the continuous improvement of experimental techniques available to the scientists. It is achieved mostly through increasing the number of controlled parameters, number of detectors, and sample environment systems used in the experiment. The quality is enhanced also by their sophistication, heightened requirements for accuracy and operation speed of data acquisition equipment, necessity to provide remote control over spectrometer subsystems and the experiment. The user policy carried out at the IBR-2 spectrometers imposes additional requirements for the equipment of the spectrometers, control systems, and data acquisition systems, which should be easy to master and easy to use, should have convenient graphic interface and provide access to measurement results via the Internet.

The development of the concept of the new pulsed fast reactor was included in the JINR Seven-Year Development Plan for
2017–2023, which is of key significance for the successful continuation of the neutron-based research program after the end of the IBR-2 service life. Based on the results of joint research work of JINR and JSC NIKIET (Rosatom State Corporation), which consisted in analyzing variants of a high-flux pulsed neutron source, the concept of the NEPTUN pulsed fast reactor with neptunium-nitride fuel was chosen for further elaboration. The main stages of the development of the concept of the new NEPTUN reactor include: development of a preliminary scientific program and determination of the composition of a suite of scientific instruments for conducting neutron research, development of technical specifications for preliminary design and infrastructure projects, scientific and technical rationale for the design of the new neutron source, as well as the implementation of the research and development program, which includes the study of the dynamics of pulsed reactors, optimization of the design of the main reactor systems, development of neptunium-nitride fuel and neptunium-nitride-based fuel rods, optimization of the configuration of the moderator complex, development of prototypes or special test stands.

 Project/Subprojects: 

Brief annotation and scientific rationale:

The main task of the project is to increase the efficiency in the use of the IBR-2 research nuclear facility for implementation of the program of experimental investigations, to ensure operational reliability and safety of the reactor.

Regular operation of the research nuclear facility IBR-2 is carried out in accordance with the Rostekhnadzor license with an average power of up to 2 MW to provide neutron beams for conducting physics experiments The IBR-2 facility is equipped with modern safety control systems, systems of analysis and diagnostics of the reactor state, systems for radiation monitoring and control of radiation situation.

Expected results upon completion of the project:

After completion of work on the subproject, JINR will continue to operate a world-class high-flux neutron source for research in the field of condensed matter physics and nuclear physics – the IBR-2 research nuclear facility of advanced safety and reliability. The suite of equipment of the IBR-2 will comprise:

1. cryogenic moderators that ensure the implementation of a cutting-edge and competitive program of physics research.

2. advanced equipment for safety-related systems of the IBR-2.

3. reserve movable reflector MR-3R, which will be fully prepared for operation to ensure guaranteed functioning of the IBR-2 nuclear facility.

Expected results of the project in the current year:

1. Obtaining a license from Rostekhnadzor for the right to operate IBR-2.

2. Check assembly, adjustment and trials of the MR-3R reserve movable reflector at the FLNP test stand.

3. Phased replacement and upgrading of the IBR-2 basic technological and electrical equipment, which is important for the safe operation of the IBR-2 nuclear facility.

4. In cooperation with the Mayak Production Association, working out and consideration of the possibility of manufacturing and supplying an additional batch of fresh fuel for the IBR-2 core in order to extend the service life of the reactor for physics experiments until 2040-2042. 

Subproject:

Brief annotation and scientific rationale:

In the framework of the theme “Development of the IBR-2 Facility with a Complex of Cryogenic Neutron Moderators”, phased realization of the project “Construction of a complex of cryogenic moderators at the IBR-2 facility” continues. The unique complex of cryogenic moderators being constructed (using a mixture of aromatic hydrocarbons of mesitylene and metaxylene in a ratio of 3 to 1, in a solid frozen phase, in the form of beads with a diameter of 3.5-3.9 mm) makes it possible to significantly increase the cold neutron flux for experimental condensed matter research.

The complex of cryogenic moderators includes three moderators surrounding the reactor core. Cold neutrons for physics experiments are produced with the CM-202 cryogenic neutron moderator (in the direction of neutron beamlines № 7,8,10,11) and the CM-201 cryogenic moderator (in the direction of beamlines № 1,4,5,6,9). These moderators are currently operating in trial operation mode. The CM-203 neutron moderator is at the stage of development of the technical design specification. The commissioning of the CM-203 cryogenic moderator will make it possible to provide cold neutrons for neutron beamlines № 2, 3.

The operation of the complex of cryogenic moderators at the IBR-2 nuclear facility greatly increases the intensity of cold neutrons compared to the thermal moderator and can significantly shorten the time of experiments and improve the accuracy of the data obtained.

Expected results upon completion of the subproject: 

1. Operation of the complex of cryogenic moderators at the IBR-2 nuclear facility, comprising three moderators CM-201,
   CM-202, CM-203, covering most of the neutron experimental beamlines of the IBR-2 facility. Reliable and trouble-free operation of the complex will allow maintaining and strengthening the leading position of the IBR-2 reactor among the world's most high-intensity research neutron sources used for condensed matter investigations by neutron scattering methods. 

Expected results of the subproject in the current year: 

1. Continuation of work on the optimization of the system of automatic control and regulation of parameters, system of charging/discharging and transportation of the moderator material (frozen mesitylene pellets) in the working chambers and pipelines of the cryogenic complex with the simultaneous use of two cryogenic moderators CM-201 and CM-202 for physics experiments.

2. In order to ensure the most efficient use of the suite of IBR-2 instruments in working with cold neutrons, it is planned to put into operation the second Linde AG cryogenic refrigerator with a cooling power of 1800 W at 10 K (KGU 1800/10). Until the end of 2023, it is planned to carry out the optimization of the operation of the cryogenic complex, develop requirements specification and project documentation for the CM-203 cryogenic moderator for beamlines 2 and 3.   

Brief annotation and scientific rationale:

Within the framework of the project, it is planned to study the structural features, magnetic ordering, dynamics, physicochemical properties of new promising materials and nanosystems that demonstrate important functional properties, the microscopic mechanisms of which are poorly understood. The list of objects of study includes multiferroic materials, alloys with giant magnetostriction and shape memory effects, low-dimensional and geometrically frustrated magnets exhibiting unusual magnetic states and properties, materials promising for use in compact electric current sources, magnetic layered nanostructures demonstrating various proximity effects, for example, the coexistence of superconducting and magnetically ordered states, organic functional materials with hydrogen bonds, complex fluids and polymers with a wide range of potential technological applications, the structural organization and properties of which can change significantly with changes in concentration and chemical composition, biological nanosystems, including lipid membranes, proteins and their complexes, the study of which makes it possible to understand the biophysical processes occurring in living organisms, the mechanisms of action and transfer of drugs, the causes of various diseases, biohybrid materials, structural materials that are widely used or planned to be used in various industrial and manufacturing sectors. In addition, it is planned to conduct applied studies of texture, residual stresses and internal organization of rocks and minerals, structural materials, objects of natural and cultural heritage, aimed at establishing mechanisms of geophysical processes, formation of defects and stressed areas in industrial products, reconstruction and analysis of ancient technologies, evolution and development of classification of fossil organisms.

Expected results upon completion of the project:

1. The realization of the scientific program of the project is expected to result in obtaining new experimental information, which will be of great importance for establishing the relationship between the structural features and dynamics of new functional materials and nanosystems and their physical properties at the microscopic level, as well as for developing modern concepts in the field of condensed matter physics, chemistry, materials science, biophysics and geophysics. A number of the results obtained can later be used to develop scientific foundations for the development of advanced technologies in the field of electronics, compact current sources, pharmacology and medicine. During the implementation of the scientific program, theoretical predictions and models will be experimentally tested, and new phenomena and regularities will be revealed.

2. The implementation of the methodological program will result in the modernization of the available spectrometers and the development and construction of new instruments at IBR-2, which will expand the scope of their application for interdisciplinary scientific research of new functional materials and nanosystems.

Expected results of the project in the current year:

Realization of scientific program

1. Determination of the structural parameters and phase composition of intermetallic functional materials, including magnetostriction Fe-Ga alloys and shape memory alloys.

2. Determination of parameters of the atomic and magnetic structure of low-dimensional magnetic materials in a wide range of thermodynamic parameters (temperature, pressure).

3. Analysis of high-pressure effects on the structural and magnetic properties of functional materials.

4. Analysis of complex structural and microstructural states of solid electrolytes and electrodes for metal-ionic accumulators.

5. Determination of the crystal structure and analysis of the dynamics of functional materials with molecular complexes and ionic liquids.

6. Establishing of phenomena and effects, related to coexistence of magnetism and superconductivity in layered nanostructures composed of transition, rare-earth and other metals.

7. Determination of structural characteristics of carbon nanomaterials, single wall carbon nanotubes on substrates.

8. Determination of structural characteristics and aggregation kinetics in fullerene solutions with different polarity, and in fullerene solutions with various amino adducts.

9. Analysis of structural properties of magnetic nanosystems, including colloids, composites with magnetic nanoparticles, aggregation effects in magnetic fluids and core-shell nanostructures.

10. Determination of structural characteristics of polymer systems on substrates, surfactant micelles in bulk and on the surface, surfactant-micelle complexes.

11. Analysis of structural organization of polymer nanomaterials, glass transition of polymers and polymer thin films.

12. Analysis of physical and biological properties of lipid and native membranes, protein interactions, structure and properties of protein and membrane-protein complexes, crystallization of proteins.

13. Determination of structural characteristics and study of properties of biohybrid complexes.

14. Determination of residual stresses and microstrains in constructional materials and bulk products, geological objects.

15. Texture analysis of biological and paleontological objects, construction materials and earth rocks.

16. Analysis of internal organization and construction of 3D models of cultural and natural heritage objects, industrial materials and products using neutron radiography and tomography.

Realization of instrument development program for the IBR-2 spectrometers

1. Installation of elements of the neutron guide system of the small-angle scattering and imaging spectrometer on beamline 10.

2. Development of the neutron guide system for the new DN-6 diffractometer for studies of microsamples, aimed at improving its technical parameters and expanding the available range of high pressures.

3. Improvement of technical parameters and expansion of experimental capabilities of the GRAINS multifunctional reflectometer (startup of a new neutron beam chopper, development of electrochemical and liquid cells for experiments).

4. Modernization of the available IBR-2 spectrometers aimed at improving their technical characteristics, replacing obsolete and failed units.

5. Upgrade of the FSS correlation spectrometer on beamline 13 and improvement of its technical parameters. Further development of the RTOF correlation method.

 Subprojects: 

Brief annotation and scientific rationale:

The subproject is aimed at studying the features of the structure, magnetic ordering, dynamics, physical and chemical properties of novel promising functional and structural materials, complex liquids and polymers, nanosystems, geophysical objects. The explanation of microscopic mechanisms of the formation of their properties is important both for the development of modern concepts in the field of condensed matter physics, materials science, biophysics, chemistry, geophysics, pharmacology, engineering sciences, and new technological applications in energy production, electronics, biology and medicine.

Neutron methods for studying matter (diffraction, small-angle scattering, reflectometry, inelastic scattering, radiography and tomography) provide detailed information about the atomic and magnetic structure and dynamics of materials at the atomic and nanoscale levels. Due to the peculiarities of the interaction of slow neutrons with matter, neutron scattering methods are highly effective in determining the positions of light atoms surrounded by heavy ones, studying the distribution of elements with close atomic numbers, studying isotopic substitution processes and magnetic structures. This provides great advantages when using neutron scattering methods in the study of a wide range of promising functional materials and nanosystems compared to other approaches.

To ensure the solution of the scientific tasks of the project, it is planned to carry out work to ensure the uninterrupted operation, modernization and reconstruction of the existing spectrometers of the IBR-2 reactor, as well as to complete the work on the creation of a new small-angle scattering and imaging spectrometer. Along with neutron methods, complementary methods of
X-ray scattering, Raman, atomic force spectroscopy, etc. with the application of additional laboratory equipment, will be used to improve the efficiency of solving the tasks.

Expected results upon completion of the subproject:

1. The realization of the scientific program is expected to result in obtaining new experimental information, which will be of importance for studying the relationship between the structural features and dynamics of new functional materials and nanosystems and their physical properties at the microscopic level, as well as for developing modern concepts in the field of condensed matter physics, chemistry, materials science, biophysics and geophysics. The obtained results can later be used to develop scientific foundations for the development of advanced technologies in the field of electronics, compact current sources, pharmacology and medicine. During the implementation of the scientific program, theoretical predictions and models will be experimentally tested, and new phenomena and regularities will be revealed.

2. The implementation of the methodological program will result in the modernization of the available spectrometers and the development and construction of new instruments at IBR-2, which will expand the scope of their application for interdisciplinary scientific research of new functional materials and nanosystems.

Expected results of the subproject in the current year:

Realization of scientific program

1. Determination of the structural parameters and phase composition of intermetallic functional materials, including magnetostriction Fe-Ga alloys and shape memory alloys.

2. Determination of parameters of the atomic and magnetic structure of low-dimensional magnetic materials in a wide range of thermodynamic parameters (temperature, pressure).

3. Analysis of high-pressure effects on the structural and magnetic properties of functional materials.

4. Analysis of complex structural and microstructural states of solid electrolytes and electrodes for metal-ionic accumulators.

5. Determination of the crystal structure and analysis of the dynamics of functional materials with molecular complexes and ionic liquids.

6. Establishing of phenomena and effects, related to coexistence of magnetism and superconductivity in layered nanostructures composed of transition, rare-earth and other metals.

7. Determination of structural characteristics of carbon nanomaterials, single wall carbon nanotubes on substrates.

8. Determination of structural characteristics and aggregation kinetics in fullerene solutions with different polarity, and in fullerene solutions with various amino adducts.

9. Analysis of structural properties of magnetic nanosystems, including colloids, composites with magnetic nanoparticles, aggregation effects in magnetic fluids and core-shell nanostructures.

10. Determination of structural characteristics of polymer systems on substrates, surfactant micelles in bulk and on the surface, surfactant-micelle complexes.

11. Analysis of structural organization of polymer nanomaterials, glass transition of polymers and polymer thin films.

12. Analysis of physical and biological properties of lipid and native membranes, protein interactions, structure and properties of protein and membrane-protein complexes, crystallization of proteins.

13. Determination of structural characteristics and study of properties of biohybrid complexes.

14. Determination of residual stresses and microstrains in constructional materials and bulk products, geological objects.

15. Texture analysis of biological and paleontological objects, construction materials and earth rocks.

16. Analysis of internal organization and construction of 3D models of cultural and natural heritage objects, industrial materials and products using neutron radiography and tomography.

Realization of instrument development program for the IBR-2 spectrometers

1. Installation of elements of the neutron guide system of the small-angle scattering and imaging spectrometer on beamline 10.

2. Development of the neutron guide system for the new DN-6 diffractometer for studies of microsamples, aimed at improving its technical parameters and expanding the available range of high pressures.

3. Improvement of technical parameters and expansion of experimental capabilities of the GRAINS multifunctional reflectometer (startup of a new neutron beam chopper, development of electrochemical and liquid cells for experiments).

4. Modernization of the available IBR-2 spectrometers aimed at improving their technical characteristics, replacing obsolete and failed units.

5. Upgrade of the FSS correlation spectrometer on beamline 13 and improvement of its technical parameters. Further development of the RTOF correlation method.

Brief annotation and scientific rationale:

An analysis of the state of research in the field of condensed matter dynamics using inelastic neutron scattering (INS) at FLNP has shown that the existing NERA inelastic neutron scattering spectrometer, which some time ago successfully competed with similar facilities in European neutron centers, is now significantly outdated and no longer meets the needs of the user community in the Eastern European region. Therefore, an extremely important task is to upgrade the INS spectrometer in the historically established research area in order to maintain the competitive position of the FLNP JINR in the field of neutron spectroscopy among other world neutron centers.

A promising approach is the creation of a new high-luminosity INS spectrometer that will use modern neutron optics and new design solutions to obtain high-resolution results with a good signal-to-background ratio over a wide range of energy transfer and using the smallest possible mass of the sample under study. This approach is proposed to be used to develop and construct a universal inverse geometry INS spectrometer BJN (Bajorek-Janik-Natkaniec). The combination of the high flux of the IBR-2 pulsed neutron source, modern focusing neutron optics, energy analyzers with a very large surface (two analyzers with an area of ~3.3 m²) will ensure the maximum possible luminosity of the spectrometer being developed, while the gain factor compared to the NERA spectrometer can be up to a factor of 400.

The main range of scientific problems for which the BJN spectrometer will be used, includes:

– investigations of structural phase transitions at the microscopic level;

– study of proton diffusion processes in systems with different types of hydrogen bonds;

– study of the dynamics of protons in molecular crystals in a wide energy-transfer range;

– investigations of associative interactions of chemical particles, including systems with the formation of hydrogen bonds of various types;

– investigations of magnetic dynamics in compounds with 4f and 3d transition metals.

List of research objects:

– molecular crystals and their phase derivatives;

– pharmaceutical preparations in the bulk form and in the form of “micronized” or “amorphous” powders;

– new biologically active compounds, including nanostructured ones;

– energy storage materials;

– intermetallic compounds of 4f and 3d transition metals;

– catalysts;

– photonic materials for industrial applications;

– nanocomposite materials.

Expected results upon completion of the subproject:

1. Development and construction of basic elements of the BJN spectrometer.

Expected results of the subproject in the current year:

1. Development of technical documentation for the creation of a number of spectrometer elements.

2. Purchase of pyrolytic graphite crystals to develop a focusing analyzer.

Collaboration

Brief annotation and scientific rationale:

The conduction of condensed matter investigations at a state-of-the-art level is characterized by continuous improvement of experimental techniques, increase in the number of controlled parameters as well as in the number of detectors and sample environment systems used in the experiment and their sophistication, heightened requirements for accuracy and operation speed of data acquisition equipment, necessity to provide remote control over spectrometer subsystems and the experiment as a whole, and requires constant development of both the spectrometers and IBR-2 research nuclear facility, including in particular, the complex of cold moderators. The user policy carried out at the IBR-2 spectrometers imposes additional requirements for the equipment of the spectrometers, control systems, and data acquisition systems, which should be easy to master and easy to use, should have convenient graphic interface and provide access to measurement results via the Internet, etc.

Expected results upon completion of the project:

1. Commissioning of BSD-A detector at HRFD on beamline 5 of the IBR-2 reactor and obtaining the first experimental results.

2. Development of a vector magnet based on asymmetric Helmholtz coils, with a temperature control device for low (1.5 K) and ultra-low (down to 0.5 K) temperatures for the REMUR reflectometer.

3. Development of technical documentation for the equipment of control systems of the complex of cryogenic moderators of the IBR-2 reactor; commissioning of control systems for the collector unit and cooling pipelines, and cryogenic moderators CM-201, CM-202 and CM-203; installation of a dispatching system with a server that integrates control over the entire complex of cryogenic moderators, commissioning of the dispatching system.

4. Introduction of PLC-based control systems.

5. Installation of a new chopper on beamline 8 of the IBR-2 reactor.

6. Introduction of automatic PLC-based control systems to control the vacuum integrity in the channels.

7. Development and manufacture of PSC with a cathode of different diameters.

8. Development of a test stand to test the characteristics of PSD.

9. Optimization of data acquisition system based on multichannel digitizers.

10. Development of a standard module of a PSD system based on resistive-wire tubes with a cathode diameter of 6 mm.

11. Development and commissioning of a new detector system for the REMUR spectrometer.

12. Modernization of direct beam detectors at the YuMO spectrometer.

13. Development and fabrication of direct-beam monitor at the YuMO spectrometer.

14. Development of the architecture of a multi-gap ¹⁰B-PPRC, manufacture of the prototype and study of its characteristics.

15. Development of a multi-counter system for the inelastic scattering instrument being designed on beamline 2 of IBR-2.

16. Adjustment and testing of the ASTRA-M detector at the FSD spectrometer.

17. Development of a technical design for the BSD-FSD backscattering detector for the FSD spectrometer. Adaptation of scintillation detector manufacturing technologies (existing in the SC Department) for the BSD-FSD detector. Development of mechanical components of the detector, detector electronics and data acquisition and accumulation electronics for
    BSD-FSD.

18. Development and manufacture of a new ±90°-detector with combined electronic and time focusing, similar to the
    ASTRA-M detector on the FSD spectrometer.

19. Development of detector electronics and data acquisition, pre-processing and accumulation systems for new detector systems. Introduction of CAEN digitizers into the measuring systems of IBR-2 spectrometers.

20. Introduction of PLCs into control systems of spectrometers. Equipping spectrometers with video surveillance systems. Introduction of new measuring devices and controllers at the request of instrument responsibles. Automation of the vacuum control system on spectrometers NERA, SKAT, FSD, FSS. Automation of the control system of the magnet current source for the DN-12 cryostat. Unification of temperature control and regulation systems used on IBR-2 spectrometers.

21. Development of a new cryostat for cooling high-pressure chambers at the DN-12 diffractometer.

22. Development and implementation on the IBR-2 spectrometers of a new version of the Sonix+ sotware package and related systems adapted to work with the event list data format.

23. Continuous modernization (in cooperation with LIT) of the FLNP local area network segment.

24. Simulation of spectrometers or its elements for the purpose of modernization of operating spectrometers and for the development of the new one.

25. Commissioning of an automated storage of containers with irradiated samples and an automated sample positioning system at the irradiation facility.

26. Providing of uninterrupted operation of all spectrometers on IBR-2 beamlines.

Expected results of the project in the current year:

1. Manufacture of spare units for the MPD32-USB3 data acquisition and accumulation system.

2. Adjustment of CAEN amplifier modules in accordance with the required parameters.

3. Manufacture of a set (432 pcs.) of I/O and measuring cables.

4. Dismantling of the BSD detector and installation of the BSD-A detector at the HRFD diffractometer on beamline 5 of the IBR-2 reactor.

5. Development of technical design of the magnet.

6. Fabrication of the cryostat stand.

7. Development and testing of the control system of the cryogenic moderator CM-201 in the direction of beamlines
   1, 4, 5, 6, 9.

8. Development of a technical design of a new chopper for beamline 8 of the IBR-2 reactor.

9. Installation and commissioning of ASTRA-M detector at the FSD spectrometer. Development of a detector module and DAQ system for the multidetector system of the DN-12 spectrometer, tests of DAQ elements at neutron beamlines of the IBR-2 reactor. Development of the prototype of the detector module with analogue electronics for the NERA spectrometer. Development of infrastructure for the development of neutron detectors.

10. Development of a technical design of a flow cryostat with He-4 circulation with cooling by a closed cycle cryocooler to achieve a temperature range below 2K. Selection and purchase of equipment and accessories. Fabrication of new windings and assembling of the SC magnet for the DN-12 spectrometer.

11. Simulation of SANS instrument for the future neutron source in FLNP.

12. Introduction of CAEN digitizers into the measuring systems of IBR-2 spectrometers (FSD, FSS, HRFD).

13. Support and development of the SONIX+ software on requests of responsibles, based on USB-3 adaptation of SONIX+ software for the operation with DAQ controllers. Development of the new version of SONIX+ software adjusted for the operation i list mode.

14. Improvement of the concept of the central data repository, taking into account the experience gained in its operation and practical testing of possible ways of its implementation.

15. Study of radiation resistance of different materials at irradiation facility.

16. Incorporation of new measuring devices and controllers at the request of instrument responsibles.

Subprojects: 

Brief annotation and scientific rationale:

At present, the HRFD detector system consists of three detectors, two of which are located at scattering angles of ±152°, and the third one at 90°. The first two detectors are mainly used to study the structure of polycrystals, and the third one is employed to measure internal stresses. The detecting element is Li-glass-based scintillators. From the present-day viewpoint, these detectors have two disadvantages: high sensitivity to γ-background and insufficiently large solid angle (~0.16 sr). Due to this, the resulting diffraction spectra have a rather high background and a low (by modern criteria) data acquisition rate, despite the fact that the neutron flux at the sample position is sufficiently high (10⁷n/cm²/s).

To eliminate these shortcomings, in 2017 it was proposed to replace the existing backscattering detectors shown in Fig. 1 with a new wide-aperture scintillation detector based on the ZnS(Ag)/⁶LiF scintillator using combined electronic-geometric focusing. Its implementation will make it possible to radically improve the parameters of the HRFD diffractometer and bring it to the leading positions in the world. Estimates show that the use of the new wide-aperture detector will allow an approximately two- to three-fold increase in the number of experiments, along with a significant improvement in the accuracy of the obtained structural information, and the expansion of the capabilities of the diffractometer for performing experiments under various external conditions at the sample position.

Expected results upon completion of the subproject:

1. Commissioning of BSD-A detector at HRFD on beamline 5 of the IBR-2 reactor and obtaining the first experimental results.

 
Expected results of the subproject in the current year:

1. Manufacture of spare units for the MPD32-USB3 data acquisition and accumulation system.

2. Adjustment of CAEN amplifier modules in accordance with the required parameters.

3. Manufacture of a set (432 pcs.) of I/O and measuring cables.

4. Dismantling of the BSD detector and installation of the BSD-A detector at the HRFD diffractometer on beamline 5 of the IBR-2 reactor.

Brief annotation and scientific rationale:

Reflectometry of polarized neutrons is an experimental method for studying low-dimensional metal heterostructures, polymer films, biological systems, the free surface of liquids, magnetic fluids, and requires experimental equipment that includes a special magnetic system. The developed magnetic system―a vector magnet―will allow changing the direction of the magnetic field in two directions and will have an aperture that allows placing a temperature control device at low and ultra-low temperatures, as well as a neutron and gamma-ray detection system. The vector magnet will be installed on the REMUR reflectometer on beamline 8 of the IBR-2 reactor.

Expected results upon completion of the subproject:

1. Development of a vector magnet based on asymmetric Helmholtz coils, with a temperature control device for low (1.5 K) and ultra-low (down to 0.5 K) temperatures for the REMUR reflectometer.

Expected results of the subproject in the current year:

1. Development of technical design of the magnet.

2. Fabrication of the cryostat stand.

Brief annotation and scientific rationale:

The IBR-2 reactor is a unique neutron source, which is used to study the structure and physical properties of condensed matter. Information about objects under study is obtained using specialized neutron scattering instruments (spectrometers) by applying various research techniques. The quality of the obtained information is largely determined by the characteristics of the neutron source and the quality of experimental equipment. The IBR-2 pulsed reactor is a high-flux neutron source with a power of over 1 MW. The key requirements for the equipment of scientific instruments are the most efficient use of the thermal neutron flux within the framework of the implemented methodology. The equipment of any spectrometer is quite diverse and includes elements that form a neutron beam, systems for detecting neutron and other types of radiation, various systems for monitoring and controlling experiments, special equipment for creating the required conditions at the sample position during measurements, etc. At the same time, all elements and mechanisms must perform their functions under conditions of increased radiation load and ensure uninterrupted operation for long periods of time. Each spectrometer is a unique object even within the framework of the implementation of one and the same technique at the same source. Despite the fact that the equipment of IBR-2 instruments includes a number of standard elements, their configuration is always unique and requires special attention.

This sub-subproject is aimed at fulfilling the tasks of designing and developing reliable and efficient elements of spectrometers for comprehensive support of experimental work and obtaining high-level scientific results.

The high qualification of the personnel of the Department of the IBR-2 spectrometers’ complex (SC) and their extensive experience in the development and operation of equipment and control systems for the IBR-2 spectrometers will undoubtedly make it possible to implement this sub-subproject aimed at further improving the experimental infrastructure of the IBR-2 reactor. The sub-subproject consists of 7 sections, each representing a separate element of the experimental infrastructure.

Expected results upon completion of the subproject:

1. Development of technical documentation for the equipment of control systems of the complex of cryogenic moderators of the IBR-2 reactor; commissioning of control systems for the collector unit and cooling pipelines, and cryogenic moderators CM-201, CM-202 and CM-203; installation of a dispatching system with a server that integrates control over the entire complex of cryogenic moderators, commissioning of the dispatching system.

2. Introduction of PLC-based control systems.

3. Installation of a new chopper on beamline 8 of the IBR-2 reactor.

4. Introduction of automatic PLC-based control systems to control the vacuum integrity in the channels.

5. Development and manufacture of PSC with a cathode of different diameters.

6. Development of a test stand to test the characteristics of PSD.

7. Optimization of data acquisition system based on multichannel digitizers.

8. Development of a standard module of a PSD system based on counters with resistive anodes and a cathode diameter of 6 mm.

9. Development and putting into operation of a new detector system for the REMUR spectrometer.

10. Modernization of direct beam detectors at the YuMO spectrometer.

11. Development and fabrication of direct-beam monitor at the YuMO spectrometer.

12. Development of the architecture of a multi-gap ¹⁰B-PPRC, manufacture of the prototype and study of its characteristics.

13. Development of a multi-counter system for the inelastic scattering instrument being designed on beamline 2 of IBR-2.

14. Adjustment and testing of the ASTRA-M detector at the FSD spectrometer.

15. Development of a technical design for the BSD-FSD backscattering detector for the FSD spectrometer. Adaptation of scintillation detector manufacturing technologies (existing in the SC Department) for the BSD-FSD detector. Development of mechanical components of the detector, detector electronics and data acquisition and accumulation electronics for
    BSD-FSD.

16. Development and manufacture of a new ±90°-detector with combined electronic and time focusing, similar to the
    ASTRA-M detector on the FSD spectrometer.

17. Development of detector electronics and data acquisition, pre-processing and accumulation systems for new detector systems. Introduction of CAEN digitizers into the measuring systems of IBR-2 spectrometers.

18. Introduction of PLCs into control systems of spectrometers. Equipping spectrometers with video surveillance systems. Introduction of new measuring devices and controllers at the request of instrument responsibles. Automation of the vacuum control system on spectrometers NERA, SKAT, FSD, FSS. Automation of the control system of the magnet current source for the DN-12 cryostat. Unification of temperature control and regulation systems used on IBR-2 spectrometers.

19. Development of a new cryostat for cooling high-pressure chambers at the DN-12 diffractometer.

20. Development and implementation on the IBR-2 spectrometers of a new version of the Sonix+ sotware package and related systems adapted to work with the event list data format.

21. Continuous modernization (in cooperation with LIT) of the FLNP local area network segment.

22. Simulation of spectrometers or its elements for the purpose of modernization of operating spectrometers and for the development of the new one.

23. Commissioning of an automated storage of containers with irradiated samples and an automated sample positioning system at the irradiation facility.

24. Providing of uninterrupted operation of all spectrometers on IBR-2 beamlines.

Expected results of the subproject in the current year:

1. Development and testing of the control system of the cryogenic moderator CM-201 in the direction of beamlines
   1, 4, 5, 6, 9.

2. Development of a technical design of a new chopper for beamline 8 of the IBR-2 reactor.

3. Installation and commissioning of ASTRA-M detector at the FSD spectrometer. Development of a detector module and DAQ system for the multidetector system of the DN-12 spectrometer, tests of DAQ elements at neutron beamlines of the IBR-2 reactor. Development of the prototype of the detector module with analogue electronics for the NERA spectrometer. Development of infrastructure for the development of neutron detectors.

4. Development of a technical design of a flow cryostat with He-4 circulation with cooling by a closed cycle cryocooler to achieve a temperature range below 2K. Selection and purchase of equipment and accessories. Fabrication of new windings and assembling of the SC magnet for the DN-12 spectrometer.

5. Simulation of SANS instrument for the future neutron source in FLNP.

6. Introduction of CAEN digitizers into the measuring systems of IBR-2 spectrometers (FSD, FSS, HRFD).

7. Support and development of the SONIX+ software on requests of responsibles, based on USB-3 adaptation of SONIX+ software for the operation with DAQ controllers. Development of the new version of SONIX+ software adjusted for the operation i list mode.

8. Improvement of the concept of the central data repository, taking into account the experience gained in its operation and practical testing of possible ways of its implementation.

9. Study of radiation resistance of different materials at the radiation research facility.

10. Putting into operation of new measuring devices and controllers at the request of instrument-responsible scientists.

 
Collaboration

Brief annotation and scientific rationale:

In 2020/23, within the framework of the closing theme “Development of the conceptual design of a new advanced neutron source at JINR”, important results were obtained, which are of key significance for the successful continuation of work on the development of a new high-flux neutron source at JINR. Based on the results of joint research work of JINR and JSC NIKIET (Rosatom State Corporation), which consisted in analyzing variants of a high-flux pulsed neutron source, the concept of the NEPTUN pulsed fast reactor with neptunium-nitride fuel was chosen for further elaboration. The development of the concept of the new NEPTUN reactor was included in the JINR Seven-Year Development Plan for 2017–2023.

The main stages of the development of the concept of the new NEPTUN reactor include: development of a preliminary scientific program and determination of the composition of a suite of scientific instruments for conducting neutron research, development of technical specifications for preliminary design and infrastructure projects, scientific and technical rationale for the design of the new neutron source, as well as the implementation of the research and development program, which includes the study of the dynamics of pulsed reactors, optimization of the design of the main reactor systems, development of neptunium-nitride fuel and neptunium-nitride-based fuel rods, optimization of the configuration of the moderator complex, development of prototypes or special test stands (for example, an experimental test stand or a prototype of a reactivity modulator, a prototype of experimental fuel elements, test stand for a mesitylene-based cryogenic moderator with a system for continuous reloading of the working material, etc.).

The work performed is a serious R&D groundwork laid down in the period from 2020 to 2023, requiring the continuation and development of the above stages to move from the concept stage to the stage of the draft design of the new NEPTUN reactor.

Expected results upon completion of the project:

1. Development of the scientific program and the concept of the suite of instruments for conducting research in condensed matter physics, nuclear physics and applied research at the new NEPTUN pulsed reactor.

2. Building a model of the dynamics of pulsed fast reactors.

3. Development of neptunium nitride fuel and neptunium-nitride-based fuel rods.

4. Optimization of the vessel and reactivity modulator of the NEPTUN reactor.

5. Conducting neutron-physics calculations to select optimal materials for use as a cryogenic moderator at the new NEPTUN reactor. 

Expected results of the project in the current year:

1. Preparation of materials for the development of the scientific program and the concept of a suite of scientific instruments of the NEPTUN reactor.

2. Preparation for conducting experiments in accordance with the program of work under the agreement between JINR and RFNC-VNIITF on the development and verification of a mathematical model of the dynamics of the NEPTUN pulsed reactor.

3. Obtaining the first batch of neptunium oxide for testing the technology of manufacturing fuel for experimental fuel rods and conducting pre-reactor studies of fuel compositions under the agreement on the development of neptunium-nitride fuel and neptunium-nitride-based fuel rods between JINR and JSC VNIINM.

4. Preparation of materials for the technical specification for the draft design based on the results of optimization of the reactor vessel and the reactivity modulator.

5. Analysis of the efficiency of using hydrogen-containing materials (methane, triphenylmethane, liquid hydrogen, deuterium, etc.) as a cryogenic moderator at the new NEPTUN reactor (IBR-3) and their comparison with mesitylene. Development of working design documentation for a chamber-simulator of a cryogenic mesitylene-based moderator with a system for fast loading and unloading of working material.

Subproject: 

Brief annotation and scientific rationale:

In accordance with the roadmap of the NEPTUN project, the next major stage after the completion of the stages of preliminary design and development of a technical proposal is a draft design. A draft design is developed to determine the principal (constructive, schematic, etc.) solutions for the product, giving a general idea of the working principle and (or) the design of the product. On the basis of the draft design, a justification for investments is developed, which is an obligatory document in the development of such a complex facility as a research reactor (Decree of the Government of the Russian Federation N306 of 14.03.1997).

At the draft design stage, the development and selection of basic technical solutions, the study of structural and functional schemes of the product, the selection of basic structural elements, etc. are carried out. As a rule, at this stage, one or two variants of the reactor are considered from among those recognized as feasible at the conceptual design stage.

The choice of a specific core configuration option is the most important moment and the key point of the entire project of construction of the NEPTUN reactor. This is due to the fact that the technical solutions fixed in the draft design, further at the next stages (technical design, working design documentation), being included in the voluminous design documentation, can only be changed with great difficulty. Therefore, already before the draft design stage, a thorough study of all controversial and ambiguous points is required, as well as R&D and calculations (kinematic, electrical, thermal, etc.) that confirm the operability and reliability of the product in all specified operating conditions.

The main goal of the subproject is to conduct research and development work to justify the development of a draft design of the NEPTUN reactor. These R&D include: development of neptunium nitride fuel and neptunium-nitride-based fuel rods; study of dynamics of the pulsed reactor; optimization of the design of the reactivity modulator and the reactor vessel in terms of reducing thermal loads and shape changing; development and implementation of a list of R&D to justify the development of the draft design.  

Expected results upon completion of the subproject: 

1. The scientific program and the concept of the suite of instruments for conducting research in condensed matter physics, nuclear physics and applied research at the new NEPTUN pulsed reactor.

2. A working variant of the dynamic bending model and evaluation of the effect of the pellet-type structure of fuel elements (compared to the pin-type structure) on the reactivity of dynamic bending at the beginning of the fuel lifetime and verification of calculations at RFNC-VNIITF. Technical specification for conducting experiments to check the shape of the bending of a fuel element prototype under rapid heating in the neutron flux of pulsed reactors. Setting up an experiment on pulsed neutron sources of RFNC-VNIITF.

3. Obtaining a permit for the use of nuclear materials that are exclusively in federal ownership (NM EFO). Production of the first batch of neptunium oxide for the refinement of the fuel manufacturing technology for experimental fuel rods and conducting pre-reactor studies of fuel compositions. Development and manufacture of a trial batch of experimental fuel rods based on neptunium nitride.

4. Development of two variants of the reactor vessel design with the lowest thermal load and temperature deformations for the rod-by-rod core configuration and the configuration of the core with jacket fuel assemblies. Development of two variants (with and without a jacket) of the design of the reactivity modulator, operable in all specified conditions. Possibility of developing a technically justified alternative design of the modulator and reactor vessel. A list of R&D activities necessary to substantiate the design of the reactivity modulator, its components and the reactor vessel. Working design documentation for a full-scale stand (prototype) of the reactivity modulator. Start of manufacture of some elements of the stand (prototype) of the reactivity modulator according to the developed working design documentation. Technical specifications for the development of draft design and infrastructure (conceptual) projects.

5. Conducting neutron-physical calculations to select optimal materials for use as a cryogenic moderator at the new NEPTUN reactor. Development of working design documentation for a full-scale test stand of a mesitylene-based cryogenic moderator with a system for fast loading and unloading of working material.

Expected results of the subproject in the current year:

1. Obtaining the first batch of neptunium oxide for testing the technology of manufacturing fuel for experimental fuel rods and conducting pre-reactor studies of fuel compositions under the agreement on the development of neptunium-nitride fuel and neptunium-nitride-based fuel rods between JINR and SC “VNIINM”.

2. Preparation for conducting experiments in accordance with the program of work under the agreement between JINR and RFNC-VNIITF on the development and verification of a mathematical model of the dynamics of the NEPTUN pulsed reactor. Preparation for conducting experiments on vibroacoustic, thermomechanical, hydrodynamic measurements of the parameters of the model of the dynamics of the NEPTUN reactor on the basis of the JINR experimental facilities.

3. Report of SC “NIKIET” on the results of R&D on optimization of the reactivity modulator and the NEPTUN reactor vessel. Development of working design documentation for a test stand (prototype) of the reactivity modulator.

4. Analysis of the efficiency of using hydrogen-containing materials (methane, triphenylmethane, liquid hydrogen, deuterium, etc.) as a cryogenic moderator at the new NEPTUN reactor (IBR-3) and their comparison with mesitylene. Development of working design documentation for a chamber-simulator of a cryogenic mesitylene-based moderator with a system for fast loading and unloading of working material.

5. Preliminary scientific program and the concept of a suite of scientific instruments for conducting research in condensed matter physics, nuclear physics and applied research at the new NEPTUN pulsed reactor (IBR-3).