[en] Full text: At the WWR-K reactor there is a universal loop facility (ULF), which is designed to provide the necessary test conditions in the experimental channels of the core. By means of the ULF, necessary environment (nitrogen/helium/vacuum at the predefined pressure and temperature) is created in a channel which houses a sample under studies. To support the reactor tests, the ULF is equipped with the measurement/information system, which makes it possible to provide operators and experimentalists with on-line test-related information. The measurement/information system is a complete set of some technical means (microcontrollers, analog and digital signals modules, power supply units, etc.) and software. (authors)

[en] The conversion of the VVR-K research reactor to low-enrichment uranium fuel includes switching to a compact core with low-enrichment uranium and gradually transitioning from a light-water side reflector to a beryllium reflector with restoration of the working reactivity margin without makeup with fresh fuel. In 2015, the reactor was stopped in order to modernize the main elements of the core, the control and protection system for the channels of the working rods, and the emergency electric power source. First criticality of VVR-K with low-enrichment fuel followed by first start of the reactor occurred in spring 2016. The VVR-KN type FA specially developed for VVR-K make it possible to not only preserve but also improve the neutronphysical characteristics of the core. The design-basis reactivity margin of the working core load ~7%Δk/k is adequate for reactor operation for three 20-day cycles with ~10% average burnup reached in the central FA. The beryllium reflector is built up in stages starting at the fourth cycle. The beryllium reflector will make it possible to preserve the radial dimensions of the core and increase the neutron flux density in the central and peripheral irradiation channels.

[en] WWR-K reactor is a unique multipurpose research reactor in the Republic of Kazakhstan. The first physical start-up of the WWR-K reactor had been carried out in October of 1967. WWR-K is a water-water heterogenic reactor with thermal neutrons and design power of 10 MWt and U-235 enrichment of 36 %. It worked without any deviations and emergencies till 1988. After Chernobyl accident in April of 1988 it was adopted by regulatory body of the former Soviet Union the decision to shutdown it permanently in order to carry out works on enhancing of seismic safety of the reactor. Since 1998 the reactor had been put into commission at the power 6 MWt. Since 2003 it was began feasibility studies on conversion from high enriched uranium fuel to low enriched uranium fuel with preservation of operation and experimental features. As a result of these studies it had been designed a new fuel assembly named after VVR-KN. A new reactor core had been elaborated. Life test of three lead test assemblies was carried out and it was reached more 50% of U-235 their burnup. Conversion of the reactor had being carried out within the framework of the IAEA program “Russian Research Reactor Fuel Return” and the International Program on Reduced Enrichment for Research and Test Reactors (RERTR). Taking into account Fukushima Daiichi Accident it had been adopted the decision alongside with the conversion to carry out modernization of the reactor systems under the above mentioned programs. I&C, emergency cooling, emergency core sprinkling, primary cooling, secondary cooling, radiation monitoring, gas and aerosol emissions monitoring systems have been modernized. Physical and power startups of the reactor had been successfully carried out in the first half of 2016. Since September of 2016 the WWR-K reactor operation with low enriched uranium fuel was started. (author)

[en] The Institute of Nuclear Physics using WWR-K research reactor were carried out studies to develop the technology of neutron-transmutation doping of silicon ingot with a diameter of 150 mm and a height of 200 mm. As a result, was obtained silicon ingot with an uneven electrical resistivity at the level of ∼6%. In 2017, together with the Chiyoda Technol Corporation, (Japan) were started the activities to develop a technology of neutron-transmutation doping of large sized silicon with a diameter of more than 150 mm and a height of up to 500 mm for the WWR-K reactor. The main goal is to achieve an irregularity electrical resistivity in terms of the volume of the silicon ingot at the level of 3-4 %. At the first stage, were performed the works on the formation of the thermal neutron field in irradiation device. The object of investigation is a silicon ingot with a diameter of 150 mm and a height of 500 mm. For reduction of the height irregularity are used neutron absorbers arranged along the height of the ingot. The development of irradiation device with a neutron absorber and the corresponding neutron measurements were performed at the critical facility. The silicon ingot is modeled by a block of the aluminium. At the second stage it is planned to perform the works on the WWR-K reactor to test the developed technology with the further irradiation of a silicon ingot. (paper)

[en] The WWR-K is a multipurpose research reactor in the Republic of Kazakhstan. The WWR-K reactor was started up for the first time on October 30, 1967, under the direction of B.T. Dubovsky, V.N. Okolovicha, G.A. Batyrbekova, L.A. Yurovsky, and A.I. Maslova. The WWR-K research reactor is a water-water reactor of a heterogeneous type with a thermal neutron spectrum, a rated capacity of 10 MW, and a 36% enrichment of uranium-235. The reactor operated without any accidents until 1988. After the Chernobyl accident, the USSR Gospromatomnadzor decided to suspend the operation of the WWR-K reactor in October 1988 until the requirements for ensuring safe operation of the reactor under high seismicity conditions were met. Specialists at the Institute of Nuclear Physics endeavored to increase the seismic safety of the reactor and to provide for its safe operation in conditions of high seismicity. In 1998, the operation of the WWRK reactor was resumed with the permitted power of 6 MW. Prior to the collapse of the USSR, the main purposes of the WWR-K reactor were testing the thermionic reactor-converter elements, neutron activation analysis, studies of ultracold neutrons, studies of inert gas plasma parameters, and studies of the electroionization of CO₂ and CO lasers. In 2003, a feasibility study was begun for the conversion of the reactor to lowenriched fuel with preservation of operational and experimental capabilities. As a result, a new fuel assembly, WWR-KN, was designed on its basis—a compact core, which allows improving the characteristics of the reactor. During the period from 2011 to 2013, the life-cycle tests of three test assemblies were conducted; on the basis of the test results, the WWR-KN FA was recommended for the conversion of the WWR-K reactor. In the first half of 2016, successful physical and power startups of the WWR-K reactor with low-enriched fuel were carried out. As a result of the conversion, the thermal neutron flux in the center of the core was doubled. The main current purposes of the WWR-K reactor are the following

• testing fuel and structural materials of reactors of the fourth generation;

• testing fusion reactor materials;

• producing radioisotopes for medicine and industry;

• neutron activation analysis.

[en] A joint research is conducted between KINP and JAEA as a part of the international standard of instrumentation. In this research, the irradiation test of the LVDT is started under the partner project of the International Science and Technology Center (ISTC) from May 2010. The irradiation test is carried out to evaluate the durability of two kinds of LVDTs made of the MI-cable and the ceramic-wire under the neutron irradiation conditions. The nuclear and thermal-hydraulic design of the irradiation capsule was calculated by INP and JAEA. The irradiation capsule with LVDTs installed was developed in JAEA. This irradiation capsule is installed in the cell 5-9 in the WWR-K core. Irradiation tests are started on April 5, 2011. The total time of irradiation is 5465 hours. In each irradiation cycle, the ratio (E) of the primary-minus-secondary to primary-plus-secondary coil voltage and electrical resistance of the LVDTs are measured at various temperatures before and after the WWR-K operation. The value of E obtained for the shutdown reactor, of the MI cable-type LVDT is almost stable within the range from room temperature to 300^oC. On the other hand, the value of E for the ceramic wire-type LVDT changes greatly at 270^oC. The electrical resistance of MI cable-type LVDT is increased proportionally to the temperature. However the electrical resistance of ceramic wire-type LVDT changes at 270^oC. In the operating WWR-K, these phenomena are observed at 6MW. In this presentation, irradiation effect on the studied ratio and electrical resistance of these LVDTs is discussed. (author)

[en] At the research reactor WWR-K (Institute of Nuclear Physics, Ministry of Energy, Almaty, Kazakhstan) work on the creation of a new experimental facility for research using neutron radiography and tomography method has begun. It is planned that the facility will form a neutron beam with a cross section of 200 × 200 mm, with a characteristic parameter L/D of 130, using a vacuum collimator system. To obtain neutron radiographic images, a specially designed detector system based on a ⁶LiF/ZnS scintillation screen and a high-resolution high-sensitivity video camera with a rotated mirror will be used. To protect the video camera from radiation, a two-mirror optical system is proposed. The paper presents a schematic diagram and description of the main components of the experimental setup.

[en] Highlights: • 819 GBq/mg of ¹⁷⁷Lu specific activity would be produced at the WWR-K reactor at the thermal neutron flux of 1.2×10¹⁴ cm^-2s^-1. • The activity of the parasitic radioisotope Lu-177m during this irradiation time is about 2.5% of Lu-177 activity. • K-factor is 1.5 the best match corresponds to experimental data. Production of lutetium-177 using direct nuclear reaction ¹⁷⁶Lu(n,γ)¹⁷⁷Lu by WWR-K reactor neutrons on enriched LuCl₃ (up to 82% of ¹⁷⁶Lu) is described. Calculations were performed by MCNP6 transport code. Two different irradiation positions of the WWR-K research reactor were considered. Estimates of the maximum specific activity of the luthetium-177 are obtained for the reactor irradiation positions located: (a) in the reactor core centre, (b) in the core periphery. In these positions, thermal neutron flux is two times different. Experimental data was shown that k-factor is 1.5 for considered irradiation positions. The study shows that for the position located in the core center, the estimated maximum specific activity of lutetium-177 is 819 GBq/mg, is to be achieved after 15 days of irradiation. For the position located in the core periphery, specific activity of lutetium-177 is 561 GBq/mg, is to be achieved after 20 days of irradiation. Ratio of Lu-177m to Lu-177 specific activity is not more than 0.025 for both irradiation positions.

[en] Lithium ceramics Li₂TiO₃ in spherical granules (pebbles) is one of the most promising functional material for use in breeder blankets of a fusion reactor. In paper the experiments on a study of tritium and helium release from lithium ceramics Li₂TiO₃ (pebbles with a diameter of 1 mm, enrichment in ⁶Li is 96 %, weight ~ 0.37 g) under irradiation at the WWR-K research reactor (Almaty, Kazakhstan) are presented. The experiments showed that the main amount of tritium is released as HT molecules (the HT yield is an order of magnitude higher than T₂ molecules yield). The release of tritium in the form of tritium water molecules was not recorded. The HT molecule yield's significant growth occurs at the initial moment with an increase in the ceramic temperature (while the T₂ molecule release drops), after which the release flux decreases to the average level. The experimental results were evaluated by a qualitative model based on the obtained analytical expression for the tritium flux from a spherical ceramic sample for the given experimental conditions.