STATISTICS OF FAILURES AND MONITORING OF THE STATE OF POOLS AND PROTECTIVE HERMETIC FENCES OF NUCLEAR POWER PLANTS

Assessment of the technical condition of the main systems and structures is one of the main stage tasks of technical diagnostics of NPP elements. One of the important elements of the hermetic volume of the protective shells of nuclear power plants is a storage pool (SP) of spent nuclear fuel (SNF). For provision of SNF storage the appropriate systems and structures are used: SNF handling system, SP cooling system and SP by itself. Pools are made of monolithic reinforced concrete with stainless steel lining intended to retain cooling water (boric acid solution) and protect the concrete from direct effect of aggressive environments. Emergency leaks may occur through the SP lining during operation of a nuclear power plant. Materials used for pool structures must be radiation resistant and resistant to a boric acid solution. The structure of the storage pool must be earthquake-proof, must allow monitoring of emergency leaks and maintain a controlled water level in case of leaks for the time period until the fuel will be discharged. Features of failures during operation, results of research and recommendations for extending the service life of storage pools at domestic nuclear power plants with VVER are considered. Assessment of the technical condition of the main structures of the SP provides for specialized research. Thus, the SP survey generally involves visual and instrumental examination of the bottom lining, internal lining, as well as concrete walls and bottom.