Robotized system for retrieving fallen objects within the reactor vessel of a nuclear power plant (PWR)

This paper presents an original teleoperated and robotized system (TRON) designed for retrieving foreign objects within lower internals of the reactor vessels at nuclear power plants (PWR). For performing these operations, the system does not require that the lower internals have to he retrieved or the fuel assemblies unloaded. The remote handler device is an articulated pole for accessing to the lower internals from the lower core plate. This cylindrical pole is capable to reach the 90% of the horizontal surface below the core barrel. In order to carry out such mission, the TRON system must be able to underwater operate inside a very complex environment and exposed to moderate levels of radiation, that could be punctually high or very high. The design and implementation of the teleoperation system is based on generic software architecture. This original architectural model has been a very useful scheme for organising TRON control tasks, since it comprises the main functional subsystems that may appear in a teleoperation system and clearly defines the interconnections among them. The use of a generic architecture for the system development has allowed guaranteed its success. The system has been tested in one of the nuclear power plants where it will work (C.N. Asco).This work has been partially supported by the Spanish Government Programmes for Research and Development (ATYCA I63/96, ATYCA I 1 0/97, ATYCA I07/98 and CDTI,EUREm-MINE TRON EU 1565