Patent ID: 6026137
Filing Date: 2000-02-15
Classification: G21C,Y02E

Abstract:
A method of backfitting a nuclear reactor having at least one outlet nozzle, an upper core support plate defining two mounting pin holes having a hole geometry and control rod guide tubes adjacent the outlet nozzle, each guide tube mounted to the upper core support plate by a two pin mounting system having two pins extending into the upper core support plate holes having a geometry, comprising the steps of:removing the two mounting pins in the two pin mounting system supporting the guide tube adjacent the outlet nozzle; andreplacing the two mounting pins with no more than two austenitic stainless steel mounting pins, the replacement pins extending into the two holes with the same hole geometry in the two pin mounting system for supporting the guide tube adjacent the outlet nozzle whereby the control rod guide tubes adjacent the outlet nozzle of the backfitted reactor vessel may be supported by two replacement pins without enlarging or drilling additional holes in the upper core plate.