I am highly disgusted by some comments, although it was expected.
The only thing I would like to say is that Nickel - Hydrogen reaction (even without lithium) can yield inconsiderable amount of neutrons. From thermal to high energetic.
I can create this on demand and it is little bit worrisome.
If you are targetting for reaching a decent COP, be prepared for this.
To be more precise, you can receive 10mSv in a few minutes.
It is not fun anymore... Take it seriously.
To all replicators: Do not perform your experiments anywhere near your house