In the first, the structural integrity of the primary containment was analyzed. The mechanical behaviour of the concrete and the reinforced concrete was evaluated with an equivalent modulus of elasticity. This is a simplified procedure. In a second alternative, the interaction between both materials was introduced in the evaluation. A sub-model was developed. A great number of elements was required. As a result, the computing resources increased. In the third procedure, beam elements were used in a sub-model of the zone of interest. The computing time was reduced. However, the development of the finite element mesh demands the skill of the designer. In all the cases, the results were in agreement.