[en] The US Nuclear Regulatory Commission's (NRC) Office for Analysis and Evaluation of Operational Data (AEOD) evaluated US Light Water Reactor (LWR) unplanned reactor scram experience in light of ongoing industry scram reduction programs in NUREG-1275, Vol. 5. The purpose of this work which covered the years 1984 through 1987 was to provide feedback to industry, the NRC staff, and the public regarding the trends in unplanned scrams at US commercial power reactors. A primary objective of AEOD's analysis was to determine the major sources of unplanned scrams for the most recent data and to determine whether the scram reduction programs supported by various nuclear steam supply system (NSSS) owners groups were addressing proper areas for future scram reduction. This addendum updates that work through March 1989. 1 ref., 4 figs., 16 tabs