IEC 61839 pdf download.Nuclear power plants – Design of control rooms – Functional analysis and assignment
1 Scope and object
This International Standard specifies functional analysis and assignment procedures (FA and A, sometimes called allocation of functions) for the design of the control-room system for nuclear power plants and gives rules for developing criteria for the assignment of functions. This standard supplements IEC 60964, which applies to the design of the control-room for nuclear power plants. The purpose of this standard is to provide specific requirements for carrying out the functional analysis and assignment required in 3.1 and 3.2 of IEC 60964, and therefore supersedes the guidance given in A.3.1 and A.3.2 of IEC 60964. This standard is applicable to the design of new control-rooms or to backfits (design renewal and design modifications) to existing control-rooms. In the latter case, particular caution is to be exercised to identify areas indirectly affected as well as those directly affected.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 60964:1 989, Design for control rooms of nuclear power plants IEC 61 771 :1 995, Nuclear power plants – Main control-room – Verification and validation of design
For the purpose of this International Standard, the definitions given in IEC 60964 and the following definitions apply: 3.1 accident conditions set of conditions identified in the safety or transient analysis reports and/or in the emergency operating procedures 3.2 functional assignment distribution of functions among the human and automated constituents of a system 3.3 human machine interface, HMI interface between operating staff and I and C system and computer systems linked with the plant. The interface includes displays, controls, and the Operator Support System interface (see man/machine interface in IEC 60964) 3.4 probabilistic risk assessment (PRA) methodological approach to identify accident sequences that can follow from a broad range of initiating events; it includes the systematic and realistic determination of accident frequencies and consequences 3.5 control function control actions performed by humans or machines for the accomplishment of a functional goal including the associated information acquisition and processing 1 ) 3.6 tasks control actions performed by humans for the accomplishment of a functional goal 1 )
4 Process of functional analysis and assignment
4.1 General description The process of functional analysis and assignment is required in clause 3 of IEC 60964 as a first step for the design of a control-room (see figure 1 ). It aims initially to identify all of the functions required to operate the plant, then to assign the functions to humans or to machines.Two basic steps are required: a) functional analysis; b) assignment of functions. They are defined respectively in clauses 5 and 6 of this standard. 4.1 .1 Functional analysis The identification of the functions (see 5.2) is obtained initially by defining general or fundamental objectives of the plant operation, i.e. safe and effective generation of electrical power, protection of the public from radiological hazards, then by breaking down the top-level functions, allowing those objectives to be fulfilled, into a hierarchy of functions where the lowest set of functions are the control functions which must then be assigned to humans or to machines. The general nuclear power plant functional analysis is a means to the identification of all the functions achieved from the main control-room. The static database of functions of different levels, obtained in the previous step, is completed by the determination of the basic operational information flow and processing requirements for plant operation (see 5.3.1 ).