More of i think that a full nucleus is a kind of tore not only nucleons. FF will be in this way the tore diameter.
This way well explains the atoms nuclei clustered because the most of the FF don't stay at nuclei giration axis.
You should rather think as nucleon tores included inside a bigger nucleus tore as below.
This way well explains the spin precession for example.
I have done this in SO(4) physics with the Clifford torus the only possible "simple" minimal Lagrangian for carrying nuclear flux.