This report provides a methodology for calculating the costs of different options for interim storage of spent fuel produced in reactor cores. It considers different technical features and storage options and defines the factors affecting all options. The report further analyses the major cost categories, calculates the net present value of each option and determines the levelized cost. It also includes a sensitivity analysis, taking into account the uncertainty of the different cost estimates. Contents: 1. Introduction; 2. Spent fuel management; 3. Tech-nical features of spent fuel storage; 4. Storage options and cost considerations; 5. Cost considerations; 6. Method of cost analysis; 7. Cost analysis; 8. Financing the options; Appendix I: AR storage enhancement: Reracking with compact storage racks in Germany; Appendix II: A stand alone AR storage facility: The TVO-KPA pool storage facility at Olkiluoto in Finland; Appendix III: An AFR storage facility: The CLAB pool storage facility at Oskarshamn in Sweden; Appendix IV: An AFR storage facility: Pool storage facilites at the Cogéma processing plant at La Hague in France; Appendix V: An AFR storage facility: The dry cask storage facility at Gorleben in Germany.