The complex of control room equipment systems is all NPP man-machine interface systems, including the main control room, backup control room, emergency control systems, control panels, communications, etc.
Modernization of the complex of equipment systems of nuclear power plant control rooms:

• Improvement of NPP operation efficiency
• Improvement of process safety

The human-machine interface (HMI) includes a wide range of engineering issues and solutions related to the interaction between the human (operator) and the machine (equipment systems) he controls.

The importance of development of HMI systems was recognized as the most important task long before the Chernobyl accident and has always remained in the focus of the IAEA.

In the context of NPP control room equipment, the main points of this topic are:

• The use of video displays in the control interface of control room operators. With the advent of video walls and individual monitors it became possible to integrate a large amount of incoming data and display it compactly and conveniently for the dispatcher.
• Presentation of incoming information in a compressed form, with the help of mnemonic schemes and abbreviations, which greatly simplifies the process of analysis of heterogeneous incoming data.
• Using new knowledge of human psychology and ergonomics in the design of dispatch systems.
• Building alarm systems and data analysis, on the basis of which the alarms are to be output.

Safety considerations are critical in the design and operation of control room systems. The HMI ensures that incoming data about the status of the station are transmitted to the operator. The incoming information should enable him to make the right decisions. If the incoming information is distorted (e.g., due to a malfunction in the display systems), the dispatcher may make an incorrect decision. Consequently, proper operation of the entire chain is of vital importance. If an effort is made to provide all types of equipment systems involved with the highest, "nuclear" class of reliability, the cost of implementing such a perfect system will be so great that it will call into question the feasibility of the plant itself. Engineers and designers of NPP control centers try to solve this problem by creating "design basis accident" scenarios and training operators to deal with situations that could be caused by failure of signaling and data transmission systems.

Alarms and alarm sensors
The differentiation of incoming alarm data and the processing of alarm sensor data is constantly improving due to the development of technology, accumulation and analysis from real-life situations. Big Data technologies as well as neural computer networks are already being used to improve analysis.

Displaying alarms on video screens
To make it easier for station dispatchers to recognize signals coming to the video displays, color-coded signals are used. For example:

Red: Immediate action by the operator in the control center is required

Yellow: A delay in the dispatcher's response to the signal is permitted. The delay time is determined by the nature of the fault and the tools available to the operator.

White: Information indicates a change in some element of the system or an automatic action in response to a change in some parameter.

Green: Automatic action taken by the safety systems. Operators must immediately check the request from the system and execute it.

Along with the output of alarms on the control room video media, audible signals on the loudspeaker systems are also used. These signals are also systematized and coded according to the type of alarm. Auditory coding by frequency is used, but no more than three signals of different types.

Because human controllers play a paramount role in ensuring the safe and reliable operation of a nuclear power plant, control centers must provide them with the most comfortable working environment possible. In the design of control room systems, these are called human operating factors. They consist of:

• work process organization factors
• Work environment organization factors

Communication facilities.
The receipt, analysis, exchange of information and efficiency of the duty shift operators depend on the correct design of the dispatch center communication systems. Efficiency of information exchange between dispatchers of the central point and dispatchers of remote points, technicians and station engineers is of paramount importance. The main requirements here are the speed of information transfer and ensuring that it is transmitted without distortion.

The complex of integrated communication system of nuclear power plant control room includes a variety of equipment:

• paging stations
• telephony
• radio stations
• IP-systems
• videoconferencing systems

It was noticed that the work of wireless communications can interfere with electronic equipment. Therefore when installing such communication systems one should be very careful, use additional shielding of equipment, refuse to use it in premises with highly sensitive electronic equipment, use network transmission more widely.

Centralization of control and distribution of monitoring
For a long time the tendency to increase the role of the plant control room as the main center of accumulation, processing and distribution of information has been preserved. The computer systems of the control room not only collect information, but are also directly involved in its distribution throughout the plant so that it can be used by those who need it: operations personnel, safety engineers, maintenance personnel, engineers, management specialists. Broadband networks allow this information to be shared throughout the plant. The accessibility of the information exchange also imposes strict requirements for its protection. In addition, these computer networks must be protected in the best possible way against the danger of viruses.

Integration
The old view of a control room as an ordinary monitoring center is becoming increasingly a thing of the past. The introduction of modern digital technologies leads to the fact that the dispatch center becomes a place of accumulation of other functions. We can say that center operators are no longer just dispatchers, but information and system managers. They have to deal with huge volumes of information and perform service and engineering functions in managing the performance of the entire plant and equipment.

This new reality also directly affects the comprehensive approach to dispatch center equipment design, which includes:

• Equipment systems to be installed must not only serve the purpose of process monitoring, but also the purpose of monitoring and diagnosing station equipment.
• Creating its own "database" and providing opportunities to work with it for analysis and consultation.
• Combining information systems for dynamic plant monitoring with other functions such as electronic document management, automated procedures, and entering information into databases.
• Using knowledge of engineering psychology when equipping control rooms.
• Use of real-time information transfer technologies.