scope:

This standard establishes time response design criteria for safety-related operator actions to be used in the design of light water reactor (LWR) nuclear power plants. The criteria are used to determine the minimum response time intervals for safety-related operator actions that are taken to mitigate design basis events (DBEs) which result in an automatic reactor trip. This standard specifies time requirements that are to be met to receive credit in the safety analysis for operator actions that initiate or control safety-related functions.

Specifically, the criteria provide bases:

(1) For establishing certain requirements for determining whether a particular action to initiate or control a safety-related system might be accomplished by operator action or must be accomplished by an automatic action.

(2) For determining when design modifications can obviate the need for automatic actions that would otherwise be required.

(3) For general guidance for hardware, such as instrumentation, controls, indicators, and annunciators necessary to support safetyrelated operator actions.