GOOD reality program? Is there such a thing?
They'll stick nick it.. that is, if it's a good one.
What they'll do is nick bits of it and add bits of their own and claim it's their own if you were to dispute it, weather you have your unopened letter or not. And have you got the money to take it court?
You can still try by sending it to the tv companies and there are many of them. But remember that on average 300 of these things from the public land on their desks every week. Gd luck anyway. To be a program creator you need marketing skills, communication skills, audience awareness and research knowledge. If sending the idea it will be required in professional format with a treatment, synopsis, series and program lenght. If it's just on a bit of paper it will go straight into the bin.. HTH