Unit specific level 1 probabilistic safety assessment (PSA) models and results are available for the four VVER-440/213 type units of the Paks nuclear power plant, Hungary. The Paks PSA is updated annually within the framework of a living PSA program. The major purpose of the updates is to obtain a quantitative expression of safety impacts from plant modifications. Numerous modifications have been made in the past 15 years including design changes, procedural improvements, administrative measures, etc. Replacement of the earlier emergency operating procedures (EOPs) with new, symptom-oriented procedures is a recent modification. It is a complex task to determine the...