As part of fire protection defense in depth, nuclear power plants and divided into separate fire areas by fire-rated structural barriers. Fire-rated penetration seals are installed to seal certain openings in these barriers. The seals maintain the fire-resistive integrity of the barriers and provide reasonable assurance that a fire will be confined to the area in which it started. The staff of the Fire Protection Engineering Section, Office of Nuclear Reactor Regulation, US Nuclear Regulatory Commission, conducted a comprehensive technical assessment of penetration seals to address reports of potential problems, to determine if there were any problems of safety significance, and to determine if NRC requirements, review guidance, and inspection procedures are adequate. The staff did not find plant specific problems of the safety significance or concerns with generic implications. The staff concluded that the general condition of penetration seal programs in industry is satisfactory. The staff also concluded that actions it had taken in 1988 and 1994 to address potential penetration seal problems increased industry awareness of such problems and resulted in more thorough surveillances, maintenance, and corrective actions. These previous staff actions, together with continued licensee upkeep of existing penetration seal programs and continued NRC inspections, are adequate to maintain public health and safety. The staff recommended several minor revisions to the NRC fire protection regulation and review guidance.