The paper describes the theory and capabilities of the SEURBNUK-2 fluid flow code developed by JRC Ispra and AWRE Aldermaston for use in containment analysis for fast reactor safety studies. It is a 2D Eulerian code and is a major extension of the SURBOUM code developed earlier by Belgonucleaire and Aldermaston. SEURBNUK-2 has a full thin shell treatment for tanks of arbitrary shape and is able to include the effects of compressibility of the fluid. To check on the codes treatment of compressibility, results are presented for SEURBNUK calculations of an Ispra test shot 114 for the expansion of a Belgonucleaire charge in an overstrong water filled vessel. Comparisons are made both with experimental results and with calculations done on the 2D Lagrangian code REXCO-H and ASTARTE-2. A thin external deforming tank is chosen for the first test of the thin shell needed within the code though in this case the fluid was assumed incompressible. The problem has already been studied by REXCO and SURBOUM VD8 and the SEURBNUK results are compared with both experiment and these calculations. Comparisons have been made of the effect of using a full bending theory for the tank as opposed to a simple membrane treatment. It is shown that the inclusion of bending terms does not alter the ultimate strains significantly but does lead to much smoother results and values of the stress components in the wall. Results are presented for calculations on a U shaped tank containing fluid with cover gas simulating a bare primary tank. Three different calculations have been done involving rigid and flexible tanks and an incompressible and compressible treatment for the water. Comparisons are made between the three solutions both as regards final tank shape and energy distributions. The paper concludes with a calculation for a model reactor geometry which includes perforated diagrids dip plate and a deformable inner tank.