Experimental data showing generation of 4He from a Pd sheet-D2 gas system observed by E. Botta et al. are analyzed by the trapped neutron catalyzed fusion (TNCF) model. The proposed mechanism of 4He generation is not the direct d-d reaction but the reactions between the trapped neutron and a Pd isotope, n-46APd reactions, with a supplemental assumption, decrease of threshold energies for (n,) reactions of 46APd in solids. The arbitrary parameter nn, the density of the trapped neutron, of the model is determined to be ~1012 cm-3, which is consistent with values determined in analyses of data in various events in the cold fusion phenomenon.