[en] The document is intended to supply the NRC and nuclear power plant licensees with basic data on the times required to penetrate forcibly the types of barriers commonly found in nuclear power plants. These times are necessary for design and evaluation of the physical protection system required under 10CFR73.55. Each barrier listed is described in detail. Where minor variations in the basic barrier construction result in essentially the same penetration time, the variations are described. Figures of barriers requiring further clarification are presented in sequential order. For each barrier, the penetration time listed is that for the hand-carried portable countermeasure which would allow fastest penetration. If two alternative countermeasures could penetrate a given barrier in about the same time, both are given. The approximate weights of countermeasures are given in order to allow estimation of the total weight of equipment which might be required to penetrate a given series of barriers. In some cases, different kinds of countermeasures are specified for very similar barriers. For example, in the discussion of walls, heavy hand tools are specified in some cases and explosives in others. This apparent lack of consistency is due to a lack of systematically collected data. In all cases, only penetration times are cited which can be substantiated by reference to the literature, and thus consistent data were not always available. The penetration times are listed with a standard deviation range. This range is intended to give some idea of the possible variations in penetration times which might be expected between several roughly equally experienced adversaries. The source of the time listed is given for each barrier, and a complete list of the references used appears at the end of the report