Does strong enough magnetic field affect radioactivity of elements? Does strong enough magnetic field affect radioactivity of elements by distorting the orbitals of nucleons in the nuclei?
 A: Yes, this can happen, but it requires fields that are much too big to impose using the kinds of static fields that we would be able to create using magnets in a laboratory. This is the nuclear Zeeman effect. The effect on the single-particle Hamiltonian is sort of to add a term of the form
$V=\frac{1}{\hbar}\mu_N g \textbf{j}\cdot\textbf{B}$
where $\mu_N=e\hbar/2mc$ is the nuclear magneton. Now in reality, this is not quite right, because the $g$ is different for spin and for orbital angular momentum, and is also different for protons than for neutrons. But for the sake of an order of magnitude estimate, this is good enough, and we can take both $g$ and $j/\hbar$ to be of order unity.
To get a noticeable effect on the orbitals, we need the perturbation to the Hamiltonian to be on the order of 1 MeV. The result is $B\sim mV/e\hbar$, or about $10^{13}\ \text{T}$.
In reality, we do see something very much like this in nuclei when they are spinning collectively. In the rotating frame (where the Hamiltonian is not actually an energy), the single-particle Hamiltonian acquires a term $j\omega$, which has the same form as the one above, except that this is now exact, and we don't have $g$ factors.
