Ab initio calculation of helium behavior in the spallation tungsten

The non-elastic reaction in spallation will produce many new light particles such as hydrogen and helium. At the same time, it also produces many new heavy species. In this manuscript a series of ab initio calculations have been performed to quantify the helium behavior in spallation tungsten, especially the effect of these spallation nuclides on the helium behavior. The following results were found: (i) The formation energies of the main spallation nuclides are positive, except tantalum; (ii) All spallation nuclides trap helium with strong positive binding energy, except tantalum; (iii) The vacancy also is the trap site for the most of spallation nuclides with the positive binding energies between vacancy and the spallation nuclides, except tantalum; (iv) Vacancy is the strong helium trap, which will not be changed with the existence of the spallation nuclides; (v) The strong binding energy between two helium atoms will not be changed by the spallation nuclides; (vi) The spallation nuclides may increase the energy barrier that a tetrahedral helium migrates between two equivalent sites.