Device for centering and aligning a fuel assembly under an upper core plate of a pressurized water nuclear reactor and method for replacing a centering pin.

摘要

The penetration opening (2) in the upper core plate (1) comprises a central part (2b) and two end parts (2a, 2c) of diameter greater than the diameter of the central part (2b). The centring pin (5) comprises a head (6) which rests via a support part (6a) on a shoulder (3a) of the opening (2), a smooth centring and positioning part (11) and a threaded part (12). The device furthermore comprises a nut (14) which is screwed onto the threaded part (12) of the centring pin (5) until it bears on a shoulder (3c) of the opening (2). The nut (14) is made irremovable by a lock washer (18) welded inside the end part (2c) of the penetration opening (2). IMAGE