Supercritical water (SCW) can be an effective cooler for nuclear reactors. All sorts of research on the subject of SCW are very important, especially bearing in mind that SCW is a non-polar solvent, while subcritical water is a polar solvent. Irradiation leads to an increase in corrosion and migration of some metals into the volume of the SCW. The transition from the supercritical state to the normal state and inversely contributes to the synthesis of substances in the SCW. On the inner surface of the convection loop, a film of corrosion products is formed, which are minerals that can protect the metal from corrosion.

The specific heat of water at the critical point increases abruptly and therefore supercritical water (SCW) can effectively cool a nuclear reactor, it would be promising to use SCW in nuclear energy. However, at high temperatures and due to radiolysis in which, along with hydrogen, oxygen, free electrons, hydrogen peroxide and free radicals are formed, SCW has increased corrosion activity.

The synchronization system is based on STM32F407VG and DP83848. The system generates pulses with a frequency of 1 to 600 Hz, a length of up to 2500 ns to synchronize the operation of the klystron modulator, master oscillator, source modulator, control equipment of LINAC. The setting of the delay of the synchronization pulses is adjustable from 0.01 to 20 μs. Synchronization system control is implemented via USB or Ethernet network via TCP/IP protocol. Implemented a set of applications for the organization of system management and monitoring of LINAC, compatible with Windows XP/7/10.

Made of austenitic steel at the NSC KIPT, the supercritical water convection loop Loop-1a was running for more than 500 hours in the first experimental session (in 2011). The materials tested in the loop were placed into a stream of water (more than 50 g/s) at a temperature of 350…400°C, a pressure of 23…25 MPa, and were irradiated by an electron beam with an energy of 10 MeV. Sediments that emerged on the inner surface of the loop were examined. The sediment mainly consisted of compounds of calcium and iron mixed with other elements. There is a possibility to increase corrosion induced by radiation due to dislocation damage, hydrogenation of metal and under the impact of active oxygen.

To study experimentally the stress enhanced corrosion of structural materials in a water coolant flow under electron irradiation, a novel design of the target irradiation cell was developed. The stress application scheme is described and the stress-strain state of samples is calculated. Hydraulic resistance of the stainless steel 12X18H10T samples loaded cell has been measured at a dedicated facility and is discussed in terms of hydraulic and hydrodynamic models. System Thermal Hydraulics calculations have shown the device capability to operate efficiently in a natural convection driven Supercritical Water Circulation Loop.

We developed planar multilayered photonic-plasmonic structures, which support topologically protected optical states on the interface between metal and dielectric materials, known as optical Tamm states. Coupling of incident light to the Tamm states can result in perfect absorption within one of several narrow frequency bands, which is accompanied by a singular behavior of the phase of electromagnetic field. In the case of near-perfect absorptance, very fast local variation of the phase can still be engineered. In this work, we theoretically and experimentally demonstrate how these drastic phase changes can improve sensitivity of optical sensors. A planar Tamm absorber was fabricated and used to demonstrate remote near-singular-phase temperature sensing with an over an order of magnitude improvement in sensor sensitivity and over 2 orders of magnitude improvement in the figure of merit over the standard approach of measuring shifts of resonant features in the reflectance spectra of the same absorber. Our experimentally demonstrated phase-to-amplitude detection sensitivity improvement nearly doubles that of state-of-the-art nanopatterned plasmonic singular-phase detectors, with further improvements possible via more precise fabrication. Tamm perfect absorbers form the basis for robust planar sensing platforms with tunable spectral characteristics, which do not rely on low-throughput nanopatterning techniques.

The specially designed in the NSC KIPT Supercritical Water Convection Loop (SCWCL) with an irradiation chamber coupled to an electron accelerator LPE-10 gives an opportunity for corrosion and mechanical tests of materials under electron irradiation. Specimens in water flow are irradiated by the 10 MeV/10 kW electron beam of the LPE-10 linear accelerator at 23...25 MPa and 350...400 degrees C. Presented are the irradiation regime parameters for the 500 hours long work session of the SCWCL.

It was studied the effect of irradiation with high-energy (10 MeV) electrons on the optical properties of nanocrystalline carbide film system silicon / sapphire substrates in a wide range of fluences of 5•1014 to 9•1019 cm–2 and subsequent annealing in vacuum in the range of 200—1200°C. It was found that radiation-induced changes in the optical properties of nc-SiC films is primarily manifested in the UV region of the spectrum associated with interband transitions, as well as in the region of the spectrum due to the absorption of intrinsic defects and disordered regions. It was established in the beginning of the annealing of defects in irradiated films has been observed at 200°C, which indicates the high concentration of carbon vacancies with the lowest activation energy. Significant changes in the optical properties of sapphire begin at fluence 5•1017 cm–2, which should be considered when using these materials under conditions of intense radiation impact.

The Supercritical Water Convection Loop with an irradiation chamber is created in KIPT. The Loop is made from stainless steel. It measures 1.2 by 1.5 m. The plant makes possible to carry out simulation corrosion tests of potential structural materials for Generation IV reactors with the Supercritical Water-Cooling (SCWR) under irradiation. Specimens in water flow at 350...400 degrees C, 23...25 MPa are irradiated by the 10 MeV/10 kW electron beam of LUE-10 linear accelerator. The monitor with powerful permanent magnets in the turning components is being devised for expeditious control of the flow water velocity.

Multilayered photonic-plasmonic structures can exhibit topologically protected zero reflection if they are designed to support Tamm plasmon modes. Sharp phase changes associated with the Tamm mode excitation dramatically improve sensitivity of optical detectors.

The 1.2x1.5 m sized Supercritical Water Convection Loop with four-channel irradiation cell was created in KIPT. The stainless steel made plant opens the possibility to carry out simulation corrosion tests of candidate structural materials for Generation IV Supercritical Water-Cooled Reactors (SCWR) under irradiation. Specimens in water flow at 350...400 degrees C, 23...25 MPa are irradiated by 10 MeV/10 kW electron beam of LPE-10 linear accelerator. The results of the four-channel cell application for 500 hours long irradiation Zr and Inconel samples are presented.

A method of remote on-line control of the temperature of objects heated by an electron beam has been developed and researched. The method is based on analysis of object radiation in optical and infrared ranges and determination of temperature using the calibration data. Experimental study of the method was conducted at an accelerator LU-10 KIPT in a mode with electron energy from 8 to 10 MeV and beam power up to 10 kW. To monitor the temperature of the irradiated samples, a Transcend video camera with a matrix of 1.3 MP operating both in visible and infrared spectrum bands was used. The camera calibration in the infrared range was executed by electric heating of a sample at the test bench. Measuring the temperature of the sample was carried out using a Chromel-Kopel thermocouple and digital meter TERA.

An electron accelerator in which magnetron guns with secondary-emission cathodes of two types are used as a particle source is described. The electron-beam parameters are investigated in an electron energy range of 20–150 keV at a pulse length of 10–50 μs. Results of target irradiation by an electron beam are represented. The target surface structure is studied by the metallographic method, and the microhardness and strength of zirconium materials are measured. The possibility of beam current control by factors of 2.5–3.5 with various methods is shown.

The paper describes the results of the work on improvement of electron linac LUE-40. This linac has been designed for nuclear physics research in the electron energy range 40...100 MeV. The main purpose is to reduce the energy spread, emittance and long-term instability of the beam characteristics. For this purpose the system of klystron high voltage stabilization and the beam loading compensation system have been developed. The improved injector has been put into operation. A new DC power supply system of the magnetic spectrometer has been installed and tested.

The system for visual monitoring of the electron beam was developed and implemented. The technique is based on registration of optical radiation, which is generated under object-beam interaction. The system comprises image transferring channel, remote-controlled digital photo-camera, connected with PC by USB-interface as well as proper software. The images obtained give information on the beam density distribution over the surface of the object being irradiated. 40 keV and 10 MeV electron beams were researched.

Control of beam parameters is important for maintenance of linac operating conditions, as well as, for securing a high-speed protection of exit channel components against the beam damage. For this purpose the beam current, beam center position and ellipse cross-section (10 MeV, 10 kW, 1 A/pulse, 300 Hz, 3.5 mu s) are measured at the output part of linac. Two similar current sensors, position sensor and water-cooled copper collimator in the gap between the current sensors were used. All the sensors of a magnetic induction type have windings on ferrite coils placed in vacuum. The system is described and the component calibration results are reported. The coefficient of beam losses during the transit through the collimator is calculated with the use of a special microprocessor placed in the ADC module which receives the signal from two current sensors. An algorithm of signal digitization eliminates the failures under the action of pulse interference. When the set threshold of beam losses is exceeded, the signal from the electron source blocking enters into the linac synchronization unit. Control of position sensor signals is carried out without beam chopping by the on-line comparison between the four position sensor signals and the current sensor signal being placed in the same case. The data on the beam parameters are displayed on the PC screen. The system is successfully used during several years.

Since 2009, the Kharkov Institute of Physics and Technology is working towards the development of equipment and methods for testing the materials for reactors SCWR (STCU project P4841). Supercritical water convection loop with a vessel, which is exposed to electron irradiation of the electron accelerator LU-10 (8 ... 10 MeV, 10 kW), provides an opportunity to study corrosion and mechanical damage of sample materials. Small quantity water sample (1 ... 3 ml) dispenser is designed for sampling the water out of the loop which is under 23.5 MPa pressure.

The Convection Loop control system for research of water parameters in supercritical and "nearby" critical state is considered. Results of experiments are presented.

The first results of the NESTOR facility commissioning are presented. 60 MeV electron linac injector has been tested and the first electron beam with project parameters was registered at the screen monitors. Electron beam was passed through the transportation channel and injection system. The beamh of electrons was observed and controlled in the screen monitors in the expected range.