Abstract: A shipping and storage system for exothermic materials where the risk of reaching unacceptably high temperatures is alleviated comprising,a) a container vessel,b) a heat sink material inside the vessel and adapted to hold and be in intimate contact with one or more packages of exothermic material, the heat sink material having an effective high heat capacity and latent heat of melting and/or vaporization such that it absorbs all of the energy produced by the exothermic material, if it reacts by reaching its reaction initiation temperature, andc) optional cooling means in the vessel and surrounding the heat sink material and packaged exothermic material.