Fiftieth Anniversary of the WWR-K Research Reactor
�The WWR-K reactor is the only multipurpose research reactor in the Republic of Kazakhstan. The first physical startup of the WWR-K reactor was carry out on October 30, 1967 under the supervision 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 design power of 10 MW, and enrichment of uranium-235 with 36%. The reactor operated without any accident until 1988. After the accident at the Chernobyl nuclear power plant, the Gospromatomnadzor of the USSR in October 1988 suspended the operation of the WWR-K reactor until the satisfaction of requirements for justifying the safe operation of the reactor under high seismicity conditions. Specialists of the Institute of Nuclear Physics have done a tremendous job of increasing the seismic safety of the reactor and justified its safe operation under high seismicity conditions. In 1998, the operation of the WWR-K reactor was restarted with a permitted power of 6 MW. Prior to the disruption of the USSR, the main utilizations of the WWR-K reactor were testing of thermionic reactor-converter elements, neutron activation analysis, studies of ultracold neutrons, studies of inert gas plasma parameters, and studies of the electroionization CO<sub>2</sub> and CO lasers. Studies of the possibility of conversion of the reactor to low-enriched fuel with saving operational and experimental capabilities were begun in 2003. As a result, a new fuel assembly WWR-KN, as well as a compact core based on it, was designed to improve the characteristics of the reactor. From 2011 to 2013, the life tests of three lead test assemblies were conducted. As a result of these tests, the WWR-KN fuel assembly was recommended for the conversion of the WWR-K reactor. In the first half of 2016, the 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 density in the center of the core was doubled. The main current utilizations of the WWR-K reactor are: (i) tests of fuel and structural materials of fourth generation reactors, (ii) tests of fusion reactor materials, (iii) production of radioisotopes for medicine and industry, (iv) neutron activation analysis.