What effects would an electron in the nucleus have? Under the understanding of quantum chemistry:


  There is a very miniscule chance that an electron could appear inside the nucleus of an atom.


What could possibly happen if this "phenomenon" were to occur?  Would it wreak havoc upon the atom and tear it apart?  Or will it bind with the protons and create a temporary vacuum?

Under my current research, the electron would jump out of the nucleus as soon as possible because this phenomenon should not occur for more than a fraction of a second. Though it shouldn't leave without some adverse effects.
An electron being at/in the nucleus results in the Fermi Contact Interaction.

This interaction can be observed experimentally through NMR, EPR, and electron capture.  

In NMR of paramagnetic compounds, chemical shifts can be far outside the usual diamagentic range. The contribution to chemical shift of the electron density at the nucleus is referred to as the "contact shift".

For more information on Fermi contact, see "Origin and meaning of the Fermi contact interaction" Theor Chim Acta (1988) 73:173-200.