Is it true that Flat screen or LCD televisions has no radiations?  

In the early days of cathode ray tubes, the electron guns fired a stream of electrons at the screen and this sometimes resulted in significant amounts of harmful radiation. Later models of CRT screen were adequately screened and the amount of excess radiation has for a long time been negligible, though many people still (wrongly) continue to believe that it can be harmful.

LCD and Plasma screens work on an entirely different system using much lower voltages and consuming much less power. They don't emit the same kind of radiation at all. In fact the only significant radiation they emit is in the visible spectrum (which is what we want, of course!)

The dangers of using any computer or TV screen are actually, as they have always been, much more due to eye strain from looking fixedly at one object for a long time and to physical strain due to poor posture and incorrect heights of desk and chair.

A computer screen should always be at or just below the normal line of sight and directly in front of the operator; the room should be normally lit, especially the area directly behind the screen and on the desktop; the screen should be placed so that there are no reflections of bright objects in the room.

Much the same applies to a TV screen except, of course, that one tends to watch TV while sitting in an armchair or sofa so that one's head is naturally tilted back. A TV is best positioned slightly above one's normal head level when seated. The room lighting, however, is just as important when viewing TV as it is when using a computer.

I never knew that. However, if that is true, that is great news. :)