If you're concerned that your microwave might be leaking radiation, there are a few things you can do to check. First, look at the door seal and make sure it's tight and free of any gaps. If the seal is damaged or loose, radiation could be escaping from the oven.
Another way to check for leaks is to put a cell phone or other electronic device inside the oven while it's running. If the device doesn't work properly or experiences interference while in the microwave, that's a sign that radiation is leaking out.
Of course, the best way to know for sure if your microwave is leaking radiation is to have it tested by a professional. But if you want to take some precautions on your own, these tips should help you out.