<p>Safeguarding lives against radiations arising after an explosion near nuclear facilities has become a vital, yet underexplored concern. This requires structures with radiation shielding capabilities even after the explosion-induced damages. This paper presents the results of an experimental and analytical study on the effects of severe air explosions on concrete slabs considering two aspects of structural damage and the transmissibility of gamma and neutron particles. Initially, the ratio of neutron and gamma particles transmitted through the slab were measured. Then the slabs were subjected to air explosion, and the amount of damage was evaluated and the ratio of transmitted particles through the damaged slabs was measured. Two approaches were applied for reducing the structural damage and radiation transmissibility of these slabs, including modifying mix design with optimum combination of admixtures and an innovative core confining method. As the first approach, several combinations of minerals, fibers, heavy fine barite and B₄C powder were examined to find the best mixture, in terms of compressive, tensile and flexural strengths and radiation transmissibility. As the second approach, the slab core was confined with spiral reinforcements. The results show that the modified concrete mixture could increase compressive and bending strengths up to 24% and 42% and reduce the transmission ratio of gamma and neutron about 19% and 26% in pre-blast tests, but after explosion, due to the imposed damage, its transmission ratio increased about 35%. The slab utilizing both optimal mix design and confined core showed excellent resistance against blast with negligible damage saving about 94% of its radiation-shielding efficiency after the explosion. The Tested slabs were analyzed in LS-DYNA and their response to explosion was studied. Parametric study showed the higher influence of spiral pitch rather than diameter on decreasing slab damage in terms of plastic strain.</p>