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Comment by macintux | Hacker News Reader

When I was in my teens, we took a class trip to a nuclear reactor being built (never completed) in southern Indiana.

I’ve long regretted I didn’t have a camera with me to capture the large sign on one gate that read (paraphrased): “Danger: Microwaves on premises”

I wasn’t sure (still am not) whether they were referring to something industrial, but the thought that household microwave ovens at a nuclear power plant were sufficiently hazardous to require warning signs like that amused me.

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The sign was most likely for pacemaker patients.

Are modern ones still susceptible?

Aren't they encased in some bio-compatible metal, essentially making them a faraday cage that should be immune even to direct exposure?

I was always under the impression that microwaves posed a hazard to pacemakers because of the magnetic fields involved, not the RF emissions themselves.

Pacemakers use magnetic switches inside the sealed device for programming and/or battery shutoff. Lots of things involve pacemaker warnings, including iPhones with MagSafe charging ports in the case.

I believe they use microwaves for inspecting the welds on pipes and such.

That's usually x-rayed if it's critical infrastructure AFAIK. Dad was a pipe fitter for Imperial Oil.

Depends on the size of the cracks you want to observe. For aircraft they use ultrasounds. I assume you dad used x-ray because methane and H2 are extremely small (they can’t be contained in, for example, water pipes, so the same goes for diagnostics and wavelengths).

Hot crude and hydrochloric acid under pressure are two I remember from his stories. He said they checked for hairline cracks. What that actually meant in practice for measurements I’m not sure.

I've done a fair amount of weld inspection / NDT. X-ray would be the only radiation based method used on a construction site. This would typically be done in batches and require the evacuation of an exclusion zone.

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