@SpookyShadow:
He doesn't need to survive one if he can dodge one. Of course, he needs to KNOW to avoid it in the first place, but....
Speed: At least
High Hypersonic+, likely
Massively Hypersonic
If the only nukes are the Fat Man & Little Boy....
Range:Causes damage
up to a dozen kilometers away
High Hypersonic+ = Mach 50 to 100. Mach 50 is 17.15 kilometers.
With even the biggest range nuke only being able to hit 12 kilometers away & Meruem being able to move 17.15 kilometers per second, if not well in excess of that....
Meruem needs only ONE second, at most, to get away from the nuke's range.
& while it's true he might not know, if he's in the war to win it, & nukes are a very new thing to WWII, odds are he'd be able to find the people researching it, or their documents to learn about nukes, & then learn how to avoid them, their radiation, & possibly treat it.
& Meruem is canonically incredibly well read. As our own page says:
"Meruem possesses immense memory and analytical skills, being able to learn and master nearly anything he comes across in a short period."
I'm very sure he'd be able to learn about nukes, given the resources or opporunities, especially if the enemy suddenly starts acting like it's their only chance.
Lastly, there's his nen abilities. A Little Boy only has range of 1.3 km, but Pre-Rose is 3 KM in range with nen, & Post-Rose is tens of KM with Nen.He can teleport to wherever his photons are, giving a nuke dodging option BESIDES simply moving.
Also, if Meruem really does have all of Shaiapouf's & Menthuthuyoupi's abilities, that'd include being able to split himself at a cellular level, as well as reconstruct his entire body structure using Youpi's abilities. If you combined that with a knowledge of radiation, he might well be able to fight it off.
Yes, Meruem did die to a bomb's poisoning, but he chose to do so, in part because he wanted to find Komugi & spend his moments with Komugi. With Komugi not a factor, & an intent to defeat the army, he could probably invest himself into learning how to counter the bombs.
(Also, he might just be able to deflect the bombs anyway, or prematurely detonate them, such as with Rage Blast.)
TL;DR - I'm confident Meruem could & likely would learn about their existence, & how to beat a nuke, if he was trying to win WWII. & if not, he's easily fast enough to dodge/deflect/destroy one, & likely while it's out of range of him, too.