In order to affect the entire northeast power grid, a nuclear weapon would have to be in the hundred kiloton or greater range, and go off at not less than thirty thousand feet, better sixty thousand feet or higher. EMP is a light speed effect, and is absorbed by any matter, and attenuated rapidly if it is produced at ground level.
Fallout is produced in greater amounts at surface burst ranges (where the initial fireball touches the ground, like it did at Trinity.) and is spread farther by as high a center of burst as possible, with surface contact maintained. That lets out something on a ship, or in a truck. It also lets out most foreseen levels of detonation available to first round untested weapons. We were just able to put together a couple of kilotons, and we tested once first.
A poorly designed weapon will produce less blast, and less dispersal of radioactive materials than a well designed weapon, but will also produce a much more highly radioactive detritus (fallout) because so much of its original material will be unfissioned plutonium, or uranium mixed with highly irradiated ground material, and fused. (Chemically fused, that is)
A city might well be rendered uninhabitable, although not completely destroyed, but the great difficulty arises from the fact that the most grievously wounded will be in close proximity to the same area that is most thoroughly contaminated by a ground level burst. It is not good doctrine to expose rescue, and medical responders to this environment at what is possibly the beginning of a period of catastrophic need for such services.
The best response possible for the country at large is for the mature but ambulatory population, (those in their fifties and sixties) to undertake the most dangerous exposures, and try to ameliorate the most egregious suffering, and the most effectual clean up at once. All others remain at distance, and provide hands off support and logistics. This requires a few thousand of our baby boom generation to put up, and then shut up, and die quietly. Every one who has ever studied this stuff knows this. Send out the old women to care for the injured and the old men to try to clean and contain the spread of radiation. Mostly all of them die, and they should be advised of how they will die, if they leave that to natural progression for radiation sickness.
You have to cordon off the area, and keep people out. Idiots will not die quickly enough to prevent contamination being spread by souvenirs. That the idiots will die eventually is only moderately satisfying.
Tris
“The problems that exist in the world today cannot be solved by the level of thinking that created them.” ~ Albert Einstein ~
