Does anyone remember the name of this movie or skit?

It takes place in a nuclear power plant control room. Old Joe is retiring after working there from the beginning.
Just before he leaves his coworkers ask him for any words of advice. He calls back to them, “You can’t use too much cooling water” and leaves.
They then have a discussion about what he meant by that. Should we use more water? Less? The camera fades away and in the distance we see a flash and a mushroom cloud rise above the city.
This will be perfect for a retirement party but I just can’t find it. Was it SNL or was it in a movie?