Investigation of kinetics of radiation gassing from polyethylene

Gas evolution from polyethylene (PE) with additions of amorphous finely-divided boron under the effect of mixed radiation of reactor as well as gamma-irradiator has been investigated. It is established that gas evolution intensity increases with the increase of boron content in the sample up to 5 weight %, which is conditioned by the increase of the absorbed dose rate due to greater contribution of the reaction 10B(n, α)7Li. Further increase of boron content does not change total absorption dose rate which is explained by the effect of thermal neutron-screening with boron. Parameters of radiation chemical reactions, proceeding in PE with hydrogen formetion (reactions of cross-linking in the amorphous phase, cross-linking in crystal phase, formation of transvinylene bonds) are presented. A conclusion is made that the values of the parameters obtained can be used for practical forecast of radiation gas evolution from biological shield of nuclear installations on the basis of the material studied