TWO-REGION FAST PULSED REACTOR BARS-5М
Research reactor BARS-5M is a two-region pulsed fast aperiodic self-extinguishing reactor designed for irradiating large-sized samples by neutron high-power short pulse. The BARS-5M is an upgraded version of reactor BARS-5. In 2013 the BARS-5 reactor was shut down and subjected to deep modernization, after which it got a new name, BARS-5М. Currently, the first criticality of BARS-5М reactor is in progress.
The reactor consists of two cores with a common mechanical test bed which design allows varying the distance between their centers in the range from 33 to 150 cm. This is achieved by remotely controlled moving of one core (movable) relative to another one (fixed). Each core is provided with an independent neutron source, a mechanism for remotely controlled charging of test samples into the central experimental channel, and a set of neutron detectors (movable and fixed, respectively). Reactor BARS-5М can operate with a core in one of the three configurations that differ in the central channel sizes and the number of fissile parts.
The basic core configuration is a cylinder comprised of six complete rings 3 cm thick each. The rings are assembled on a central steel support tube. The rings are spaced by titanic pads coming in contact with the discs along the outer edges.
A communication controller can be positioned in the space between the reactors in order to control the coupled system reactivity by varying the neutron interaction between the cores.
A pulsed rod is shaped as a sheet enveloping the outer cylindrical surface of the core. A reactance regulator (a neutron trap) containing a neutron absorber is installed in the central channel and represents an aluminum-encased cylinder made of polystyrene-boron mixture.
Each core is covered by a boron case.
A uranium-molybdenum alloy is used as a fissile material in the BARS-5M reactor core. The BARS-5 core is cooled by compressed air.
Research Guidelines:
• Development, modernization, performance study, commissioning (decommissioning) of pulse reactors with metallic core, including multiple-region reactors.
• Investigation into radiation resistance of radio electronic equipment and its circuitry.
• Investigation into physical properties of fissile materials.
• Operation of reference measuring equipment for validation of neutron fields of facilities.
• Validation of neutron fields of RFNC-VNIITF facilities.
PULSED SOLUTION REACTOR IGRIK-2
The pulsed homogeneous reactor (IGRIK-2) within the framework of the test system is designed to generate fission pulses with the duration of no less than 2 μs and to operate under static conditions on power of up to 40 kW. When developing the IGRIK-2 reactor, we incorporated the operating experience of reactors IGRIK and JAGUAR.
The reactor consists of a core vessel with a mechanism of pulsed rods containing a neutron absorber; a test bed comprised of a rack-mounted bed plate and an observation platform and designed to accommodate the core vessel; process equipment for storing and feeding the fuel into the core vessel; and a control board.
The reactor fuel is a uranyl sulfate solution (UO2SO4) in light water doped with a homogeneously-loaded absorber (salt CdSO4). The volume of the solution in the technological system does not exceed 136 liters. The primary structural element of the reactor is the core vessel constituting a thick-walled hollow cylindrical vessel with a central channel for irradiated samples. The core vessel of reactor IGRIK-2 has a rather complex design.
The power contour is made of steel 30 CrMnSiN and consists of four welded pieces bolted at the top for additional strength. Inside the core vessel, there is a cavity of a complex shape for fuel solution. At the top, the cavity has «a labyrinth» designed for dissipation of kinetic energy of the dispersed solution following the fission pulse. The cavity also houses shell cases of pulsed rods and an emergency shut-down rod. To avoid the contact of the solution with the power contour material, the entire inner surface of the cavity is covered by a stainless steel weld with the total thickness of about 5 mm. Such a design implements to some extent the earlier solutions applied at reactor JAGUAR that is also protected by a rust-resisting jacket. However, as for the core vessel of reactor IGRIK-2, we managed to raise the concept of power contour sealing to a completely new technological level. The core vessel manufacturing was accompanied a considerable amount of research and testing. The core vessel of reactor IGRIK-2 is undoubtedly a high-technology product manufactured with a high degree of accuracy, intended for and tested at peak loads that occur during the reactor operation, with appropriate safety factor.
The development of reactor IGRIK-2 was driven by the need to study radiation resistance of various objects.
Appropriate design solutions, a large-sized central channel, equipment with a large set of various neutron and gamma-ray photon converters provide for the reactor high performance and its potential use in new applications. The reactor design provides the largest possible values of neutron fluence and gamma-ray photons dose in the maximum possible volume available to accommodate irradiated samples.
The irradiated samples can be housed in the central channel and/or outside of the reactor near the lateral surface of the core vessel, for example, opposite a lead screen, where neutron fluence reaches its maximum values. Samples are loaded into the central channel by means of a special mechanism installed at the loading device.
It is expected to use the reactor as a powerful laboratory source of neutron and gamma radiation.
Main areas of research:
• Physical research and testing of circuitry and radioelectronic equipment for radiation resistance.
• Investigation into mechanical and thermal characteristics of fissile materials.
• Running neutron diffraction and biomedical experiments.
• Investigation into neutron-physical и dynamic properties of research reactors of solution type.
SOLUTION PULSE REACTOR YUAGUAR
The research reactor YUAGUAR (nuclear homogeneous uranium aperiodic reactor) is a pulsed solution-core reactor.
The first stage of the YAGUAR reactor physical start-up began at the end of 1988. The reactor was commissioned for service in June 1990. The reactor control and safety system was modified and the YAGUAR reactor building was reconstructed during the period from 2009 up to 2013, the first criticality after the modification was completed in 2014, the reactor was commissioned for service in 2014 for a term of 10 years.
The YAGUAR reactor configuration comprises a core vessel with radiation protection, a process system and a reactor control and protection system. The reactor vessel with a pulse-rod mechanism is mounted in the reactor hall, where gamma-ray and neutron detector units, actuating element control units with pneumatic drives, and ancillary equipment are located.
During fission pulse generation the control system and the pneumatic drives provide synchronous movement of two pulse rods using a special actuation system for electropneumatic valves, which are available in the pneumatic drive system. The drives allow the rods to be moved independently.
The fuel composition of the YAGUAR reactor core is a high-concentrated solution of uranyl sulphate salt in light water with a small amount of cadmium salt. The core vessel is designed so that during a fission pulse the fuel solution can move vertically as well as horizontally.
Of special note are the unique experiments on direct measurement of the neutron-neutron scattering cross-section performed on the YAGUAR reactor (in cooperation with Joint Institute for Nuclear Research).
Main areas of research:
1. Investigations into radiation resistance of devices and their element base during irradiation experiments.
2. Analysis of thermophysical and stress-strain properties of fissile materials.
3. Neutron and physical studies of fissile material solution systems.
4. Basic research in the field of nuclear physics and elementary particles.
TEST BENCH FOR CRITICAL ASSEMBLIES FKBN-2
The test bench for critical assemblies is designed for determining critical configurations and neutron-physical characteristics of the systems containing metallic fissile materials. The development of the physical vessel of fast neutrons (FKBN) – that was the name of the first test bench for critical assemblies designed for studying critical systems of metallic uranium and plutonium – was started right after the Institute foundation. As early as March 1958, the first FKBN was put into operation. In 1970 it was moved to a new building and substantially modernized. The upgraded facility was called FKBN-M and it remained in operation until the end of 1998, having reached the end of its service life. Using the test benches FKBN and FKBN-M for critical assemblies, a great scope of work was made to study critical parameters of various systems with metallic uranium and plutonium, including the cores of pulse nuclear reactors under construction.
In October 2000, a new test bench for critical assemblies was launched. It was called FKBN-2, and in 2001, it was put into operation. Critical parameters of various systems containing metallic uranium and plutonium as well as various fissile materials are still being investigated using the FKBN-2. The main features of the new FKBN-2 are the improved mechanical accuracy of manufacturing parts and nodes of the test bench, including precise knowledge of compositions of materials used; automation and computerization of the neutron flux registration system with recording and storing the measurement protocol on a magnetic carrier; computer audio and video monitoring of the process of assembling with recording the information on a magnetic carrier; equipping the building, the control panel room, and the experimental hall with state-of-the-art physical protection devices.
Currently, the FKBN-2 has five sets of parts made of fissile materials. Sets 1-4 consist of semispherical layers, which when assembled, form spherical systems of highly enriched uranium and plutonium. Set 5 (ROMB) consists of discs made of highly enriched uranium and plutonium, as well as discs and rings made of various non-fissile materials. The FKBN-2 is mainly used for substantiating nuclear safety of technological operations with devices that are developed at the Institute; and for obtaining precise data on characteristics of breeding systems in benchmark experiments for verification of codes and correction of neutron constants.
In 2011, a new method was implemented in the test bench to measure the value, which characterizes fast transient neuron processes in the system under study without regard to its state, i.e. the prompt neutron lifetime. This is a derivative of a constant for prompt neutrons decay in a system with respect to the value, which is linearly related to reactivity. As it turned out, this value is reliably measured and calculated, and can serve as a quality test for calculations of the system state (reactivity) and time characteristics of transient processes on prompt neutrons (prompt neutron lifetime). After implementing this method, critical measurements moved to a new level of quality and became a reliable instrument for determining the reactivity of a system under study without its disassembling, and the fast neutron processes (prompt neutron lifetime).
Main areas of research
1. Development, modernization, performance study, commissioning (decommissioning), operation of test benches, critical assemblies and research reactors.
2. Nuclear physics research using test benches for critical assemblies for substantiating nuclear safety, refinement of nuclear constants and verification of mathematical models and calculations. 3. Identification of physical and radiation properties of nuclear materials and components of subcritical systems.
Miscellaneous
The results of investigations obtained at the complex of facilities described above are used for calculations of many technical devices, including calculations of explosive chambers using chemical explosives to produce artificial diamonds, calculations of atmospheric flows development and currents of the World Ocean in order to study the transport of environmentally hazardous substances.
The research in the fields of high energy density physics, plasma physics, laser thermonuclear fusion, and laser media gave rise to the following achievements: for the first time in the world, an ultraviolet nuclear-pumped laser (the NPL) was put in operation, the effect of thermal overheating on the NPL characteristics was discovered, four new laser media were discovered, and laser generation on six new transitions of atoms and ions was obtained. The developments in the field of diode-pumped solid-state laser are currently underway. A unique physical installation was built on the basis of the first Russian gigawatt frequency diode-pumped solid-state laser.
In the nearest future, plans call for the building of powerful effective laser-reactor devices for their application in the national economy and military science.
Many research results were implemented in the civil economy of Russia. The Neutron Therapy Centre for the treatment of a number of oncological diseases has been established and successfully provides medical services. The development and production of special optical fiber and optical fiber for communication systems (multi-mode and single-mode optical fibers, laser optical fiber) have been rapidly growing in recent years. High-brightness LED production technology is under development (light-emitting diodes for traffic lights, full-color screens, white light sources).
Starting from 1996, RFNC-VNIITF in collaboration with the P.N. Lebedev Physical Institute (LPI) has been implementing the semiconductor quantum-dimensional heterostructures growth technology program. The first practical problem was the development of a technology for production of semiconductor structures for high-brightness light-emitting diodes, though the capabilities of the technology are substantially wider and include:
- quantum-dimensional laser heterostructures for all types of semiconductor laser diodes; - heterostructures for highly effective radiation-resistant space-based solar cells; - infrared photoreceiving heterostructures; - nitride and silicon-carbide semiconductor structures for high-temperature and radiation-resistant microcircuits.
