The originally designed drain mode and operation mode of high-pressure steam conducting pipe to TC4F-52 type steam turbines in Qinshan Nuclear Power Plant No.3 have been analysed.It is believe that the large amplitude of fluctuation in electric power generated from the unit is resulted from the problems existing in the design of high-pressure steam conducting pipe

having drain entering into the steam turbine.Regarding to this

modification scheme of the drain mode in high-pressure steam conducting pipe has been put forward.Results of operation show that the drain mode after modification has more thoroughly solved the problems of large amplitude fluctuation in electric power generation from the said unit.