At Nuclear Power Plant (NPP), aging management is performed as part of the Periodic Safety Review (PSR) in accordance with the Nuclear Safety Act. The purpose of the aging management program (AMP) is to manage the integrity of structures, systems and components (SSCs) in NPPs over time and use. Through this, aging deterioration is mitigated to increase equipment life and secure long-term operation safety. Fuel Oil Chemistry is one of the AMPs. Through this program, aging management is performed for storage tanks, piping and other metal components that contact with diesel fuel oil. The program is focused on managing loss of material due to general, pitting, crevice, and microbiologically-influenced corrosion (MIC) and fouling that leads to corrosion of the diesel fuel tank internal surfaces. The fuel oil aging management method currently applied to NPPs in Korea measures the concentration of water and particulate contamination in the oil, analyzed the trend, and periodically cleans and inspect the inside of tanks. Among them, in monitoring MIC, a direct analysis and monitoring of the amount of microorganisms may be more effective. In this study, a method for improving the MIC monitoring system for diesel fuel oil systems was reviewed by reviewing reference documents including NUREG 1801 and examining the methods actually applied in US NPPs.

Recently, ambrosia beetles have become very important pest of 2~5 year old apple trees with M9 dwarf rootstocks in South Korea. The beetles have killed the branches and stems of the young trees, especially, frozen damage trees in winter or drought stressed tree in spring. By the increase in planting area and weaken property in winter of M9 dwarf rootstock, ambrosia beetles are becoming a key pest in Korean apple orchards using M9 rootstock. According to the survey of damaged apple trees by ambrosia beetles, Xylosandrus germanus Blandford, Xyleborus apicalis Blandford and Xyleborinus saxeseni (Ratzeburg). These insects are hosts of the ambrosia fungi. ITS region of rDNA has shown to be a useful source for phylogenetic studies and identifying speices in previous published articles. We analyzed the nucleotide sequences of ITS1, 5.8S and ITS2 region of ambrosia fungi isolated from three ambrosia beetles, in order to observe molecular variation among the fungi strains and to reveal phylogenetic relationships.