How Many Actuation on Nikon d3000 Before it Broke Down?

I wonder how many actuation can my slr survive?
I'm about 8k allover

There's no "set in stone" magic number. Just like a car, it has more to do with how well you take care of it.

The manufacturer could say the "average" MTBF is 100, 000 actuations. Your camera could only last 24, 000 or it could go 1, 000, 000+, there are too many variables to be able to say. BUT, like anything else, the better care you take of it, the longer it should last.

The D3000 is rated for at least 100, 000 actuations. This doesn't mean that when you shoot the 100, 001 frame the shutter will break - it just means that the likelihood of it happening will increase above this figure. It's like car mileage - some shutters will go on considerably longer than this.

Semi-pro DSLR's are rated to 150, 000, pro DSLR's to around 300, 000.

No one knows.

I have an old Nikon D100 made in 2002 that has over 220, 000 shutter actuation's and the shutter has yet to breakdown.

A colleague has a newer Nikon D3 with over a million shutter cycles on it and it is going strong.

My guess is in about 2014 you will want to upgrade your fine D3000 for more advanced features, but the shutter will still be performing very well.

Nikon has had over 50 years experience making cameras and shutters. My guess is that the shutters will outlast the user

I don't know but I must comment on the answer mentioning a D3 that has already done over 1000000 actuations. In three years tops.
That is the equivalent of more than 75 36 shot films every day, no holidays no down time. Thats an 11 hour movie. Is the D3 a cine camera?

Manufacturer's usually rate their dSLRs to last 100, 000 shutter actuations. That is not a guarantee though that the camera will last that long or will stop functioning at that point. There are those that break down way before that number and there are those that are still very much alive after getting past it. The safest thing to do is to take very good care of your equipment so it will serve you as long as possible.