The generated fragments due to the explosion of vessel under pressure may be threats to the surrounding equipments at the impact. The fragment characteristics are number, shape, mass, departure angles, departure velocity. These characteristics are considered as uncertain variables. The authors propose the probability distribution for each variable. A fragment trajectory model concerning its shape is then presented in order to study the impact problem. The numerical simulations using the Monte-Carlo method allow calculating the probability of impact, Pimp between fragments and surrounding equipments.