I was so leary of microwaving when I first heard about it. All my research since tells me it's no big deal. And BTW, I am a RadTech/Radiation Therapist by trade, and my college textbooks talk about this. Under EXACTLY the right circumstances a microwave could BURN you (superficially), or POSSIBLY cause cataracts, but won't cause cancer or prevent you from having kids.
NOTHING that terrible comes out of a microwave except high energy RADIO waves. These waves have less energy than visible light spectrum, the only way they could hurt you is if you sat and stared inside an unshielded microwave as it ran. In any reasonably modern machine, there are no X-rays produced, very few free electrons, and the microwaves are aimed at the food. The rest of the microwave is well shielded. I WOULD suggest you find some way to drill a hole and not take off the door, but standing behind the microwave or walking a short distance away would have greater effect.
Microwave ovens were invented when a RADAR technician's chocolate bar melted in the front pocket of his apron, and there was never any damage to his skin,m testicles, etc..... also the inverse square law shows that the beam intensity drops exponentially.
I have never microwaved a stave, but I have used this method (with my regular indoor microwave) to bend stubborn slats of tropical hardwoods or whatever for recurve overlays or handle build-ups, and it works like nothing else out there. Sometimes I soak the slats or wrap them in wet towels, but they bend like rubber and you better use gloves to handle the wood when it comes out.