A computational modeling method is presented on the fracture process of high-pressure composite shells under nonstationary heating by radiation fluxes of moderate density when physicochemical transformations and thermal inertness of composite material substantially effect the thermal energy propagation. Heat aspect of the problem takes into accaunt physicochemical transformations and their front motion deep into material. Deformation and fracture of multilayer material in the high-pressure composite shell casing are calculated within the limits of the composite material model with a brittle polymer binder. Results are supposed to be presented in the plane of surface density levels of energy and fluxes.