Investigation of Twenty-Foot Separation Distance as a Fire Protection Method as Specified in 10 CFR 50, Appendix R.

摘要

A combined experimental/analytical program was conducted to examine the adequacy of the 20-foot separation requirement, one of the requirements set forth in Appendix R of 10 CFR 50 for the fire protection of redundant safety systems that are necessary to achieve hot shutdown in nuclear power plants. Specifically, Sections III.G.2.b and d of Appendix R require separation of the redundant safety systems by a horizontal distance of more than 20 feet with no intervening combustibles or fire hazards. Section III.G.2.b also requires installation of fire detectors and an automatic fire suppression system within fire areas. The experimental investigation consisted of six full-scale fire tests of unqualifed and qualified electrical cables separated by 20 feet with no protection, protection with a ceramic fiber blanket and sheet metal covers on the cable trays, and protection with a fire protective coating.