Nuclear district heating plants AST-500. Present status and prospects for future in Russia Original Research Article

Development activity in the field of nuclear reactors for district heating purposes was initiated in the ex-USSR in the middle 1970s. It was stimulated by a growing deficiency of fossil fuels needed to provide for the heating of large cities in the European regions of the country. Construction of two pilot twin-reactor nuclear district stations was started in the early 1980s in the cities of Gorky and Voronezh. Nuclear heating reactor AST-500, developed by OKB Mechanical Engineering, has a number of unique engineering features, e.g. integral lay-out of primary systemʹs components, natural coolant circulation, steam-gas self-pressurizing system, additional safety vessel around the reactor unit, etc. All these specific features, which were adopted in order to assure enhanced safety of the reactor plant, required fulfilment of an extensive R&D program. Description of the reference AST-500 design features is given in this paper, as well as respective R&D activities carried out for the design solutions and safety validation. Currently, activity in the field is directed to AST-500 design upgrading and development and also to a whole series of heating-only and co-generation reactor plants ranging from 30 to 600 MW(th) for the new generation nuclear stations.