This Standard establishes requirements for a Level 1PRA of internal and external hazards for all plantoperating modes (low power and shutdown modes willbe included at a future date). In addition, this Standardestablishes requirements for a limited Level 2 PRA sufficientto evaluate large early release frequency (LERF).The only hazards explicitly excluded from the scopeare accidents resulting from purposeful human-inducedsecurity threats (e.g., sabotage). This Standard appliesto PRAs used to support applications of risk-informeddecision-making related to design, licensing, procurement,construction, operation, and maintenance. Theserequirements are written for operating power plants.They may be used for plants under design or construction,for advanced LWRs, or for other reactor designs,but revised or additional requirements may be needed.This version of the PRA Standard provides specificrequirements for the following hazard groups:(a) Internal Events (Part 2)(b) Internal Floods (Part 3)(c) Internal Fires (Part 4)(d) Seismic Events (Part 5)(e) High Winds (Part 7)(f) External Floods (Part 8)Technical requirements for PRAs of other external hazardsthat may be relevant on a plant-specific basis or forspecific applications are provided in Part 9. In additionto providing technical requirements for detailed PRAsof these hazards, this Standard provides requirementsfor screening and conservative analyses of external hazards(Part 6), and technical requirements for seismicmargin analysis are provided in Part 10.Many of the technical requirements in Part 2 are fundamentalrequirements for performing a PRA for anyhazard group, and are therefore relevant to Parts 3through 9 of this Standard. They are incorporated byreference in those requirements that address the developmentof the plant response to the damage states createdby the hazard groups addressed in Parts 3 through9. Their specific allocation to Part 2 is partially a historicalartifact of theway this PRA Standardwas developed,with the at-power internal events (including internalfloods) requirements being developed first, and thoseof the remaining hazard groups being developed later.However, it is also a reflection of the fact that a fundamentalunderstanding of the plant response to a reasonablycomplete set of initiating events (as defined in 1-2.2)provides the foundation for modeling the impact of varioushazards on the plant. Hence, even though Part 2 is given a title associated with the internal events hazardgroup it is understood that the requirements in this Partare applicable to all the hazard groups within the scopeof the PRA.