A collisional radiative model is applied to study the ionization,rnrecombination, and energy loss rates of an optically thin hydrogen plasma in arnTokamak thermonuclear fusion reactor. The effective ionization andrnrecombination coefficients are found to be increasing functions of electronrndensity, the increase being bigger when the temprature is low. The rate ofrnradiative energy loss is significant only in low density plasmas; and the estimaternthat has been used by most plasma modelers is pretty big that it cannot be appliedrnfor dense plasmas.rnEdge plasma cooling due to the interaction of recycling neutral particlesrnnear diverter targets with the scrape off layer is an important effect to reducernthe heat load on Tokamak vessel components. The relevant atomic data forrnhydrogenic atoms are well established, whereas the data base for molecules isrnless complete. Collisional radiative processes are considered to study the effectsrnof hydrogen molecules in the edge plasma boundary. Effective dissociation andrndissociative ionization rate coefficients are calculated. Rate coefficients for thernproduction of neutral atoms from hydrogen molecules are also evaluated. Finallyrnthe rate of electron energy loss per dissociation of molecules into atoms and/orrnions is calculated. The rate of this energy loss is significant and the dissociationrnof the molecules may account for the missing heating power in the divertorrnregion