[en] The purpose of this report is to present the results of a common mode failure analysis for the LOFT systems that have been identified as engineered safeguard features, hereinafter referred to as plant protection systems (PPS). The qualitative analysis was performed to identify potential problem areas within the LOFT facility where secondary events such as fires, missiles, etc may cause a common mode failure of redundant PPS subsystems. Thus the analysis identifies areas where additional detailed studies may need to be performed to determine if design changes are necessary such that redundant PPS subsystems will not fail as a result of secondary events. The plant was analyzed in accordance with the design existing in September 1977; that is, no assumptions were made as to the existence of proposed design changes nor of systems not yet installed