1. Field of the Invention
The present invention relates to a dual type lancing device of a secondary side of a steam generator, in which two guide rails and washing robots are installed in both directions of a hand hole, and each washing robot removes precipitates from the center of a steam generator, and therefore precipitates do not flow backwards, thereby completely removing precipitates.
2. Description of the Related Art
A steam generator of a nuclear power plant is a main equipment of a nuclear plant, which generates steam for driving a turbine and a power generator by the heat-exchange of heat energy generated by a nuclear reactor, and functions as a pressure boundary for preventing radioactivity from leaking to the outside.
In nuclear plants, a turbine is operated by a force of steam generated by heating water with heat generated during the nuclear fission of uranium (Ur), and then a power generator is driven by this rotatory power so as to generate electricity. Heat pipes are closely arranged in a steam generator, while high-temperature water that is contaminated with radioactivity is flowing in the heat pipes, and low-temperature water that is not contaminated with radioactivity is flowing out of the heat pipes, heat-exchange occurs. Then, the water that is not contaminated with radioactivity is changed to steam having high- temperatures and high-pressures, and a force of this steam rotates a turbine and a power generator, thereby generating electricity.
However, since sludge accumulates in the steam generator as a time for driving the steam generator elapses, the thermal efficiency of the heat pipe of the steam generator decreases, and the heat pipes are damaged, thereby reducing the lifetime of the steam generator. If not removing iron oxide and copper oxide that are main components of the sludge, these components are condensed and adhered between the heat pipes, thereby generating a temperature stress. In addition, while the sludge is flowing together with water, the sludge may damage the heat pipes.
In order to remove sludge that adversely affects the lifetime of a steam generator, a driving method and equipment for discharging cooling water included in the steam generator during the driving the steam generator have been used. In reality, only with this method, sludge is not removed effectively, and accumulates continuously.
Accordingly, there is a need an apparatus for effectively washing the inside of a steam generator. In addition, it is required to reduce an operation time of 72 hours taken to wash the inside of a steam generator.