The control room simulator at nuclear power plants
In depth - January 13, 2023

The control room simulator at nuclear power plants

The simulator of the control room at a nuclear power plant is an exact replica of the actual control room, down to the last detail. It has several purposes, but it is more specifically designed to train personnel and run tests in order to guarantee safety and the correct operation of the plant.

The control room at a nuclear power plant is a space that brings together all the controls and information necessary to safely manage the site's operation. It is located in the controlled area of the plant.

The control room receives signals from all the equipment, components and systems that make up the plant, which makes it possible to control them from one single location. This is the workspace for the personnel responsible for the plant's operation; here they perform all the necessary activities and tasks, from routine surveillance or maintenance operations to even emergency management.

To guarantee the safety and correct operation of the site, and at the same time train the staff that work or will be working at the control room for this type of site, the simulator is an essential tool, much like the flight simulators used by pilots for their training.

The simulator is an essential tool to guarantee the safety and correct operation of nuclear power plants

A simulator in every plant

All nuclear power plants in Spain have a control room and its corresponding simulator, also known as full-scope simulator. It is an exact replica of the control room at the site, where everything is identical — not just the many devices and control boards but also the chairs, lamps, tables, environment, and so on. It reflects the situation of all the systems on the plant. In other words, it has the same information and conditions that exist in the actual control room.

The control room simulator at nuclear power plants
Simulator of the control room at the Cofrentes Nuclear Power Plant (Photo: Foro Nuclear)
The control room simulator at nuclear power plants
A controller at the control room simulator in Vandellós Nuclear Power Plant (Photo: Foro Nuclear)

The simulator has a powerful computer that reproduces the functioning of all possible operative systems and situations at the plant. The simulation is also supported by virtual panels or software operation interfaces that replicate the hardware panels used to interact with the control devices. This guarantees maximum physical and functional fidelity.

These simulators reproduce all types of situations: routine plant management tasks, programmed events such as revisions or refuelling outages, cleaning activities or even possible accidents and incidents. The simulator's response is exactly the same as that of all the plant's systems in each of these situations. The system makes it possible to analyze and evaluate risks and accidents, as well as make predictive analyses of design changes and modifications at the plant.

Training in a simulator is one of the most important areas of the training program for nuclear operators

The double purpose of the simulator

  • Training for nuclear operators that already work at the plant and must update their training, as well as training for new operators before they take their place at the actual control room. Training in a simulator is one of the most important areas of the training program for nuclear operators. It is one of the initial steps needed to pass the official test from the Spanish Nuclear Safety Council (CSN) to get licensed. After this, they will continue to train in the simulator for the preparatory practices. The practices help operators consolidate their theoretical knowledge, become familiar with the plant's dynamics and acquire the necessary skills to operate it by practicing with start up and shut down as well as normal, circumstantial and transitory operation.
  • It is part of the routine work of the plant's controllers and supports engineering, as they must carry out retraining and ongoing learning activities in order to keep up with the latest advances. Moreover, it is used to simulate results and variables before making any change that could affect the software or the electronic or mechanical devices at the plant and ensure that the changes are safe.

The simulator trains nuclear operators and simulates results and variables before making any change that might affect the plant's systems

Technological components of the simulator

Some of the simulator's components include:

  • A simulation environment to synchronize, execute and supervise in real time the operation of the models, manage the database and debug possible errors.
  • Model generating tools, specialized in the system's typology: electric or hydraulic networks, fluids, logic and control systems, etcetera. They facilitate the automatic development of the models via a graphic interface.
  • Modelling of the thermohydraulic and neutronic area

Apart from the simulator, nuclear power plants use an interactive graphic simulator (SGI) to train their operation, engineering and maintenance personnel. The SGI graphically simulates different conditions of operation, as well as the status and evolution of the most representative components and parameters (pressure, flow, temperature, level, neutronic flow...)

Spanish simulators

The company that built the simulators for the five nuclear power plants and seven reactors operating in Spain is Tecnatom. The company also built and is building similar devices for other countries such as Brazil or the United Arab Emirates. At their headquarters in San Sebastián de los Reyes (Madrid) is the site of the control room simulator for the Trillo nuclear power plant located in nearby Guadalajara. Previously they also housed the simulator for the Almaraz Nuclear Power Plant, but in March 2021 it was transported to a special building inside the plant, which is located in the province of Cáceres. The simulators of the other plants –Ascó I & II, Cofrentes and Vandellós I & II– are in close geographical proximity (in Tarragona and Valencia), inside specially constructed buildings.

The control room simulator at nuclear power plants
Transportation of the simulator at the Almaraz Nuclear Power Plant (Photo: Tecnatom)

Tecnatom's simulators comply with all international rules and standards. The company also builds full-scope simulators globally and for multiple reactor technologies: pressurized water (PWR), boiling water (BWR), and pressurized heavy water (PHWR), etcetera. The company is currently involved in the development of simulators for some designs of the new Small Modular Reactors (SMRs).

Tecnatom is the engineering company that builds the simulators for the control rooms at nuclear power plants in Spain and many others internationally

Simulator maintenance and updating

Nuclear power plants reload fuel periodically. Trillo reloads once a year, Almaraz, Ascó and Vandellós II every year and a half and Cofrentes every two years, approximately. This means modifying the plant's nucleus.

The maintenance process of simulators includes a methodology that determines the impact in training personnel with operating license following the modification of the corresponding plant's nucleus.

Should it be determined that changing a nucleus configuration will impact the operating, the simulator is updated and the appropriate changes are made in the simulation models. Following this, a set of exhaustive tests is run to guarantee that the response from the simulator's nucleus is the same as that of the actual nucleus at the plant.

The control room simulator at nuclear power plants

During the refueling outage, tests are run to guarantee that the response from the simulator's nucleus is identical to that of the nucleus at the actual plant

Control room simulators in other countries

Similarly, all the currently operating nuclear power plants have their own full-scope simulator. Engineering companies such as the American Westinghouse or the French Framatome are continuously updating and renewing their products to ensure that all nuclear power plants can offer reliable training and simulation of their processes to guarantee safety.

Sources: Tecnatom, Foro Nuclear and Revista Nuclear España (SNE).

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