Yes. Some may remember the problems with cold fusion. I once went to a packed talk at Stanford where some physicists and chemists were trying to reproduce the effect. They mentioned that in the first attempts, they had radiation alarms set up in case the thing suddenly started emitting substantial amounts of radiation. After a while, it became clear that the effect, if it existed at all, was small, somewhere below twice background radiation, so it wasn't high risk. They discovered that people moving around the apparatus affected the results; humans have a lot of water and are neutron reflectors. Finally they did the experiment inside a "neutron cube", a box made of lead bricks, to eliminate stray neutrons. No neutron generation measured inside the cube.

They worked hard for months getting to a definitive "no".