A multitude of things like immediate death, homelessness, loss of food sources and energy, radiation diseases or conditions, among other things
blast effects
In any explosion (conventional or nuclear) most of the damage is from blast effects.
Some of the effects on the human body from a nuclear explosion are death (from thermal energy/blast effects or super lethal radiation exposure), infertility and blood disorders.
nuclear explosion?
Most illnesses were cancer related because of the ionising radiation in the nuclear fall-out after the explosion.
new clear weapons
If you are sufficiently close to the explosions center it is possible.Temperture of explosion center is 300,000,000°C.
When and what explosion? One of the nuclear test shots. If so which?Remember Chernobyl was not a nuclear explosion, it was a steam explosion and graphite fire.
The PTR level is intended to protect people and vehicles on a highway from the effects of an accidental explosion.
Many things. I'd need more details on exactly what effects you are interested in to say.
changes in genes
lots