Event Sequence [Energy] Law and Legal Definition

According to 10 CFR 63.2 [ Title 10 – Energy; Chapter I -- Nuclear Regulatory Commission; Part 63 -- Disposal of High-Level Radioactive Wastes in a Geologic Repository at Yucca Mountain, Nevada; Subpart A -- General Provisions], the term event sequence means “a series of actions and/or occurrences within the natural and engineered components of a geologic repository operations area that could potentially lead to exposure of individuals to radiation. An event sequence includes one or more initiating events and associated combinations of repository system component failures, including those produced by the action or inaction of operating personnel. Those event sequences that are expected to occur one or more times before permanent closure of the geologic repository operations area are referred to as Category 1 event sequences. Other event sequences that have at least one chance in 10,000 of occurring before permanent closure are referred to as Category 2 event sequences.”