Implementation of Optimal Oil Flushing Methodology for Nuclear Steam Turbo Generator Oil circuits - A Case Study

The objectives of this article are to elaborate the various tactics used in flushing of Prototype Fast Breeder Reactor (PFBR) 500 MW e TG oil systems, the difficulties faced while doing flushing and lessons to be remembered before starting the oil flushing of TG oil systems. TG oil circuits flushing was carried out with Turbinol 46 in three stages. Oil samples were also collected periodically to monitor the flushing performance. In this article a simple method was used to find the minimum oil required for starting the flushing and make up requirements of oil during different stages of flushing. An energy balance approach was also used to find the fraction of oil going through cooler and cooler bypass line during thermal shocking process. This study reveals that it will be possible to control the cooling time of lube oil during stage-2 flushing which leads to an increase in number of thermal shocks per day thereby flushing time can be considerably reduced.