Maintenance Management of Turbine Generator Foundation Affected by Alkali–Silica Reaction

Abstract

A change in distance between the generator rotor axis and the bearing of the table deck in the turbine generator (TG) foundation of Unit #1 of the Ikata nuclear power plant was observed during an inspection in 1979 after the start of operation. This led to measurements of the structure expansion (from 1981), the cracking condition (from 1982), and core sampling of the concrete member (from 1986), based on which deformation and cracking was determined to be the result of an alkali–silica reaction (ASR). However, as the strength of the TG foundation was still in excess of its design value, ASR was not considered to have affected its ability to support equipment. Subsequent analysis of the structural stability of the TG foundation found no change in deformation or concrete strength over a period of continued monitoring, and hence, the TG foundation has been used up to the present time. The aim of this paper is to establish a maintenance management method for similar structures exhibiting cracks caused by ASR.