Well.....your last quote isn't quite correct because in this terminology we mostly refer to "ionizing radiation" rather than just "electromagnetic"
yeah energy is mass and eternal, kind of, sort of, timey wimy wibbly wobbly
even black holes evapourate (we think)
one of the nasty things is "neutron" radiation, which isn't strictly speaking, "ionizing"
only found in reactors and bomb detonations, neutrons "activate" elements they hit, turning them into different isotopes
lot of the new isotopes are actually not harmful, but because they are truly different, they can mess up chemical bonds, hence the metals, concrete etc in a reactor can decay etc far more rapidly than normal.
this is why the materials used in such construction have to be extremely finely designed/manufactured, and need replaced every few years. Some elements cannot be used or allowed in alloys and others are added etc.
the problem with Fukushima and where the "corium" is in Chernobyl, is this neutron activation over time, increases amounts of different, dangerous radioactive elements and can dangerously affect stability of engineering/architecture that is essential
"Concrete cancer" is well known problem in building trade caused by simple chemical problem it's not a health threat to humans except by accidents, just problem so stability of the concrete, a spreading "rot"., neutron activation is in ways similar, but also incredibly toxic
Chernobyl the reactor material has cooled and so very few neutron events compared to Fukushima, but it seems at the very least one reactor core is in complete runaway, maybe 2 others at Fukushima.
this is vastly beyond Chernobyl for risk.
generally the big "baddies" are strontium, caesium, cobalt and iodine
certain isotopes of them the body thinks are other elements, so strontium gets into your bones where it triggers leukaemia's by damaging bone marrow
iodine gets into thyroid and causes cancer there
cobalt-60 is a swine as it has a half-life that's much longer than other isotopes of similarly nasty power of their emissions
as general rule, the more powerful the radiation emitted the more likely the isotope has a very short half-life "the
candle that burns twice as bright burns half as long" *he says like Tyrell*
cobalt 60 is in unfortunately, a "sweet spot" where it has half life effectively of decades and extremely harmful "tuning" as it were of the radiation
neutron activation in all these man cores and pools means more filth is bred every day so the radiation is NOT decaying (in sense of radionuclides harmful to us)
more uranium gets converted each day to heat + plutonium (but of lesser mass) + neutrons + materials nearby are "activated"
the Russians "quenched" Chernobyl by dropping sand and beryllium to "choke" the neutron cycle, like putting a guard up around a fire so it suffocates itself as it can't get enough oxygen, also, they put metal pyramids under the melting core so it hit these and got splattered around into smaller chunks which didn't have enough mass to sustain reactions, like pulling coals or logs out of a fire
So, looking at how Humans rung things...yeah, I'm a Vulcan, screw it!
"They put SIX nuclear fission reactors on top of the most highly tectonic area on the planet, by the SEA shore?!
Fascinating...tell, me, exactly how much LSD does your average leader consume, on a daily or yearly basis?"