The domino effect risk caused by fragments was investigated in consideration of the clapboard and protective layer of polyvinylchloride (PVC) resin based on the plasticity concepts.The effects of the risk reduction were explored and compared by Monte-Carlo simulations.The results showed that the clapboard only prevented the projectiles in the range of its size and reduced the impact probability of the fragments to some extent,but the protective layer cut down the failure possibility of target significantly.The relative deviations demonstrated that more than 90 % reduction in the domino effect risk caused by fragments was performed by the protective layer of PVC resin,accounting for 2 to 3 times of that produced by the clapboard.The risk of domino effect occurrence caused by fragments decreased exponentially according to the thickness of the protective layer of PVC resin,and the relationship between the two variables,of high reliability,as the theoretical basis for the design of the protective facilities of the tanks against the fragment impact,was created by data fitting.The best practice to reduce the possibility of the domino effect to the tank initiated by fragments was the use of the protective layer.