Oh, I know, Stranger. I toured a school reactor at WPI, a 10 KW thermal job, standard for most university reactors. The operator mentioned her dose for the last quarter had been on the order of 30 mREM. I whistled. She started protesting about how low that was, and then I pointed out that I’d had to do maintenance on a REAL reactor the week before my tour, and got 45 mREM in less than an hour, just from opening a drain valve on the steam generator.
Most crew men on nuclear subs actually get less radiation dose living next to a nuclear reactor when it’s underway than they do when they’re on shore. 200-400 feet of water makes for a great radiation shield.
Whoops, my bad. You’re right about the isotope. The thing of it is, all decay reactions also emit photons. And the photons are easier to detect in your stomach than are the beta particles. (That dead layer of skin and clothing thing, only from the inside, now.) Basically, it’s just easier, at a distance, to detect the gamma rays, or photons from the decay reactions than it is to detect the beta particles. Besides the detector I’d used to get screaming counts off a bunch of bananas was a gamma detector. The uninitiated get VERY nervous when an obvious radiac starts screaming at about 1000 cpm.
