Here is the scoop an radiation
Prompt:
Alpha- Fast moveing Helium nuclei that doesn’t get very far because it collides with air, slows down and captures electrons and becomes regular helium.
Beta- Very high energy electrons. The tend to get farther that alpha, but the also dont get far in air.
Gamma- Short wavelength photons. They are beyond X-ray on the spectrum, and if they interact with electons shells, the have quite enough energy to blow the electron right off the molecule/atom, ionizing it. Gamma is the key source of EMP, because it liberates a large number of electron. The urrent generated then causes very high intesity RF waves.
Black body- photons at almost every wavelength. They arent generated by the nuclear reaction, but by the intense heat of the fireball. BBR photon energy levels go all the way to soft x-rays.
Persistent/Delayed
Neutron- Fast moving neutrons that are disruptive enough to tear up cell membranes and and dna. These also are captured by everyday atoms turning them to radioactive isotopes.
Isotopes - Byproducts of the fuel fission include iodine-131, strontium-90 and 89, and cesium-137 which are very biologicly harmful.
Note that Alpha,Beta,Gama, Neutron, and X-ray are all considered ionizing radiation.
And the isotopes are dangerous because you get them on you, and they eventual decay to produce ionizing radiation.
If this all isn’t enough, a 1MT blast creats 5 kilotons of nitrous oxides, significant amounts are injected into the stratosphere where they deplete the Ozone layer.
Have a nice day 