Mouse hole, gas heating pipe and insulation foam

Hi!!!

We just moved and found a few gaps as well as what looks like a small mouse hole by one of our gas radiators. We wanted to try filling the holes with spray foam insulation however with one being very close to a pipe that runs from one radiator to another it made us worried about the foam then flaming up.

Does anyone have any suggestions as to what type of foam insulation we could use or if the radiator would even get hot enough to burn any insulation we place there???