Researchers from the University of Washington and Los Alamos National Laboratory conducted an accurate simulation of the nuclear fission process using the Summit supercomputer at Oak Ridge National Laboratory. Their work confirmed the existence of "sission neutrons", which had been controversial in the past, and refuted the idea that nuclear fission is a random process. The study focused on the "neck rupture" stage, where the nucleus stretches and splits into two parts. The simulation, which required almost a million hours of supercomputer time, revealed that this process is controlled by more complex and predictable mechanisms than previously believed. It was discovered that minor differences in the density of nuclear material determine the location of rupture long before the nucleus finally disintegrates. One of the most surprising discoveries was that the connection between the two fragments of the nucleus is mainly supported by neutrons. When the nucleus ruptures, an intense and rapid release of energy occurs. The simulation also confirmed the existence of so-called "sision neutrons" emitted at the time of nuclear rupture. These neutrons were previously the subject of debate among experts. We detected these neutrons in two modes. One of them radiates sideways as the fragments move horizontally. The other propagates perpendicular to the direction of movement of the fragments. Moreover, the spectra of these high-energy neutrons differ significantly from those of thermal neutrons, which is particularly interesting for future research.