In the context of the studies performed at JRC-Ispra for NET/INTOR, a modular stainless steel first wall, water cooled, and separated from the blanket which it envelops like a box has been proposed. During plasma disruption the metallic structure of the first wall is inevitably subject to appreciable electromagnetic forces caused by induced eddy current-magnetic field interactions. These forces produce deformations and stresses in the wall structure, which have to be considered in the design of the first wall. The behaviour of this type of structure under the electromagnetic forces mentioned was analysed. The electromagnetic forces were evaluated by means of a finite element code for shell-type structure in 3-D geometry, for the case of a 20 ms plasma disruption. The deformation and stress distributions in the first wall were quantified at various instants of time by three-dimensional calculations using the ICES-STRUDL code.