.Since an ordinary neutron that's "free" (not bound to the nucleus of an atom) will decay in an average of 15 minutes, then why doesn't a neutron star decay? The answer seems to be that the intense gravity counteracts any forces that would cause decay. However, if two neutron stars get close enough that the gravity is neutralized, it seems that they could decay - and possibly explosively.
Our simulations also make two predictions that could be tested. First, they predict that some of the ejecta expand so rapidly that some of the neutrons might escape capture by seed nuclei during the decompression. The neutrons would then decay on a timescale of minutes and produce a bump in the UV bands on a time scale of an hour. in the first hour of the merger. Second, the radio fluency from GW170817 might reveal the presence of a substantial amount of fast-moving ejecta in the next few months or years.
Neutron star mergers generically result in the ejection of a small fraction (0.1% - 1%) of a solar mass of neutron rich material. As these ejecta expands and cools, they may undergo the so-called r-process and produce heavy nuclei, like gold. The radioactive decay of by-products of the r-process can power an UV/optical/infrared transient known as kilonova.
During the merger, material is ejected from the neutron stars because of tidal torques and shocks. Most of this material is bound and forms an accretion disk around the merger remnant, a massive neutron star or a black hole. A small fraction achieves velocities in excess of the escape velocity and is unbound. Additionally, a substantial fraction of the disk (10% - 40%) becomes unbound over a timescale of a second due to magnetic and neutrino processes in the disk.