ASSESSMENT AND MANAGEMENT OF AGEING OF CIVIL STRUCTURES OF PAKS NPP

Ageing management review is an essential element of the licence renewal process. Proper ageing management has to ensure that ageing effects will be discovered and handled before the loss of the intended functions of the structures. This practice, the most important and the most frequent degradation mechanisms and effects with the involved concrete structures and structural elements, are presented and summarised in this paper. Two types of ageing management programmes are applied at Paks NPP. Programmes "A" are related to the different structural elements of the buildings or to typical ageing problems (e.g., settlement) which occur at many buildings. Programmes "B" specify the exact methods and conditions of the application of the necessary "A" programmes for the different buildings. Altogether 31 buildings are involved in the ageing management system of Paks NPP. The majority of the identified degradation problems were comparatively minor and involved mainly concrete cracking, leaching, chemical attack, corrosion of carbon steel liners, degradation of sealing and coating materials, and settlement. The main results of monitoring and theoretical analyses (in the fields of heavy-concrete structures, effect of elevated temperature, forecasting of settlement for the end of the extended lifetime, etc.) are also presented.