S. Syarip 1), Sri Nitiswati 1), Y. Sardjono 1), Tegas Sutondo 1), T.W. Tjiptono 1), Paul Stathers 2), R. Blevins 2), Kevin Thorogood 2)

Abstract:
A root cause analysis (RCA) related to the swelling problem in Kartini reactor have been done. Three areas of interest were observed from the inspection of Kartini reactor tank liner conducted in 2001 i.e.: a small area with apparent thinning, a small crack that was analysed as an original manufacturing defect, and there were two areas of swelling (bulges) observed under the thermal column. The visual inspections each year by the video equipment and replication indicate that the swelling parts observed in 2001 had grown in size. Recent examination 2006-2007 showed that the size of bulges relatively constant, and the peak of the bulges appears to contain tears (cracks). Therefore, RCA has been conducted to evaluate the problem and the result shows that probable root cause of swelling are as follows: it is probable that the seal on the cover plate in the service pool has deteriorated and allowed water to enter both the thermal column and the space between the aluminium reactor pool liner and the concrete. The water will also saturate the concrete and has the potential to corrode the steel reinforcement close to the surface of the concrete. It is believed that water leakage from the bulk storage facility (BSF) has entered the area behind the aluminium pool liner and has saturated the concrete, and also believed the carbon steel reinforcement close to the inner surface of the reactor block has corroded. The expanding corrosion product (rust) has the forced layer of concrete covering the steel reinforcement and subsequently pushing the aluminium pool liner inwards, causing the swelling. As the evidence, it has been shown that water has penetrated the concrete block of the service pool, and this is supposed to be a probable cause of the swelling. As a remedial action is to dry the concrete block to attempt to remove the conditions that are causing the defects, and the BSF would then be lined to prevent future water penetration of the concrete.