This document establishes requirements for the human-machine interface in the main control rooms of nuclear power plants. The document also establishes requirements for the selection of functions, design consideration and organization of the human-machine interface and procedures which are used systematically to verify and validate the functional design. These requirements reflect the application of human factors engineering principles as they apply to the human-machine interface during plant operational states and accident conditions (including design basis and design extension conditions), as defined in IAEA SSR-2/1 and IAEA NP-T-3.16. This document does not cover special purpose or normally unattended control points, such as those provided for shutdown operations from outside the main control room or for radioactive waste handling, or emergency response facilities. Detailed equipment design is outside the scope of this document. The primary purpose of this document is to provide functional design requirements to be used in the design of the main control room of a nuclear power plant to meet operational and safety requirements. This document also provides functional interface requirements which relate to control room staffing, operating procedures, and the training programmes which, together with the human-machine interface, constitute the control room system. This document is intended for application to new control rooms whose conceptual design is initiated after the publication of this document. If it is desired to apply it to an existing control room, special caution must be exercised so that the design basis is kept consistent.