Some of you may or may not know this but while the thought of a nuclear hand grenade does sound nice in theory, it simply doesn't isn't feasible or possible to make such a device in the real world! Why is this you may ask? Let's take a look at some key reasons why, to date, the nuclear hand grenade is simply pure fantasy:
Critical Mass and Nuclear Fusion
What usually accompanies the production of any type of nuclear weapon? You guessed it...scientists! What does that mean? You guessed it...Nuclear Weapons are darn hard to make! Millions of regular bullets and other "conventional" armaments are made each year in factories all over the world. It's a no-brainer process that has been figured out and improved upon for mass production for LITERALLY decades! Nuclear weapons on the other hand? Not so much...
Nuclear weapons are by definition complicated. That means to make just one weapon or one bomb requires many people that included the best and brightest scientists. They measure factors like "critical mass" and "nuclear fission" and make adjustments before any nuclear weapon is approved. Nuclear fission is a reaction and mass refers to quantity. Without getting heavily into the weeds what we are saying is that essentially, you need the right materials with the right kind of properties that weigh just the right quantity to get a nuclear reaction.
The reality is that we don't have the kind and or/enough material to get the required reactions to make a nuclear weapon as small as a grenade, not to mention the man-power necessary to produce tons of nuclear grenades safely so as to not accidentally decimate an entire military squadron due to a simple "accident,"
If you've been reading the above then you probably know what's coming. And that is the subject of weight. In order to make a grenade feasible and practical, it has to do the most damage to the enemy without being too heavy for the opposing soldier to carry. Unfortunately with today's technology, nothing of the sort can be manufactured successfully and on a massive scale. Nuclear grenades are a nice idea but in reality, they are just too darn heavy!
What good is any weapon if it routinely kills both the enemy and the opposing forces? Probably not very good. Nuclear explosions are supposed to be BIG. This means they are supposed to have a large blast radius and kill a lot of people. The reality is that throwing a grenade with a human arm is simply a poor "weapons delivery" system that would almost certainly result in the death of the soldier throwing such a thing, not to mention those that are in close proximity to him/her. Why? Because human beings are not capable of throwing such a grenade far enough!
The above-mentioned points should make it pretty clear as to why a nuclear hand grenade is to date, impossible but if we factored in the Nuclear Treaty on the Non-Proliferation of Nuclear Weapons then we'd, again, have another obstacle in the way. Moral of the story? Nuclear hand grenades are, for now, an idea of science fiction and not one of feasibility or practicality but probably more appropriate for gaming You decide.