SI26421A - Research reactor simulation system - Google Patents

Abstract

The Research Reactor Simulation System solves the problem of the relatively poor accessibility of research nuclear reactors for a more accurate study of reactor physics. The simulator is a teaching aid for lectures, but it can also help prepare students for hands-on exercises with a real physical nuclear reactor. The simulation system includes a console with buttons and warning lights connected by suitable connections to the microcontroller; a computer with a display connected to the microcontroller via a communication means; the simulator software code that runs on the microcontroller; computer program code that runs on the display computer. The simulator has a user interface that has buttons, switches and warning lights and other light displays.

Description

Research reactor simulation system

Field of the Invention

The present invention belongs to the field of reactor physics and simulations of nuclear reactors, as well as to the field of control systems and user interfaces. According to the international patent classification, the invention belongs to class G09B9 - Simulators for teaching or training and to class G21C1 - nuclear reactors. The invention relates to a system for simulating a research reactor.

Background of the Invention and Technical Problem

The teaching of reactor physics and nuclear engineering, as well as the training of future operators of nuclear power plants and research nuclear reactors, currently relies on standard teaching equipment (chalk and blackboard) and on practical exercises carried out on small research reactors, such as TRIGA (Training, Research, Isotopes , General Atomics) reactor.

Most educational institutions around the world do not have their own research reactors or do not have access to any of the research reactors. The percentage of research reactors and suitable pedagogical equipment for use in lectures, as well as the difficulties in successfully preparing for practical exercises on research reactors, indicate the need for a computer simulator or a simulator of physical nuclear reactors.

The technical problem addressed by the present invention is therefore the design of a research reactor simulator that will effectively and reliably simulate all aspects of the operation of nuclear reactors. At the same time, it is desirable that the solution is affordable and quickly responsive to user inputs.

Known state of the art

Some companies develop reactor simulators, but their products are intended for training nuclear power plant operators and are not suitable for classroom use. Existing simulators are less flexible and consequently less suitable for learning nuclear reactor physics and studying the characteristics of nuclear reactor cores. Furthermore, conventional simulators must create the entire control room platform present in real reactors or power plants, which increases the cost of such simulators. Such solutions are described, for example, in documents US3916444A and US3916445A.

There is little literature or other publicly available publications on simulators used to train nuclear power plant crews and predict nuclear reactor responses.

Patent application US3082546A describes a nuclear reactor simulator including movable control rods, a flexible heat source, a control means for the heat source operatively connected to said movable control rods, a heat-sensitive transistor circuit, the transistor of which is exposed to the heat source, and a display, including at least a meter adapted to display the response of the transistor circuit to the heat source as an indicator of the response of the nuclear reactor to the position of the control rods. This solution differs from the present invention in terms of user interface and performance characteristics.

Micro-simulation Technology has developed TRIGA (http://www.microsimtech.com/triga/) a simulator that mainly focuses on reactor secondary systems and less on reactor core physics. The simulator itself is conceptually flawed, as it includes borated water, which TRIGA reactors do not use. As a result, the simulation processor does not reflect the real conditions in TRIGA reactors. Furthermore, this simulator does not allow changing the physical parameters of the reactor, such as characteristics of delayed neutrons (effective fractions of delayed neutrons, lifetimes of prompt neutrons, decay constants of delayed neutrons and progenitors of delayed neutrons), values of control rods, and the like. This simulator is also too slow to show the behavior of the reactor in real time.

The simulator, built at the Czech Technical University in Prague, is intended for promotional, not educational, purposes. It has a control panel with a joystick to move the control rods and buttons to control the simulation, as well as a computer screen that shows the simulation parameters: reactor power and fuel temperature. More information about this simulator is not available.

In Brazil, IPEN (Instituto de Pesquisas Energeticas e Nucleares) developed a reactor simulator (Ricardo Pinto de Carvalho and Jose Rubens Maiorino, A Research Reactor Simulator for Operators Training and Teaching, PHYSOR-2006, ANS Topical Meeting on Reactor Physics, Organized and hosted by the Canadian Nuclear Society. Vancouver, BC, Canada. 2006 September 10-14), which is very similar to this company's microsimulation technology and is focused on secondary systems rather than the reactor core. The reactor is controlled via a user interface on a computer screen. The functionality of the simulator differs from the present invention.

Description of the solution to the technical problem

Currently known simulator solutions have several disadvantages, namely, they are less realistic, slower and less flexible compared to the simulator according to the invention. The aim of the invention is to solve the aforementioned disadvantages. The technical problem is solved as defined in the independent claim, while preferred embodiments are defined in the dependent claims. Part of the simulator according to the invention, especially the physics of its operation, was described in the article by Malec et al. (2020; doi: 10.1016/j.anucene.2020.107630), the contents of which are fully incorporated into this paper.

The essence of the invention is that the simulator system of the research reactor, which is based on three control rods, which are adapted to control the chain reaction in the simulated reactor and consequently its power, includes:

- a computer program that can be executed on a computer, whereby the program is adapted to perform the following:

o simulating the behavior of the reactor core, o selecting and/or adjusting the physical parameters of the reactor core, such as the size of the core, kinetic parameters of the reactor (e.g. effective fractions of delayed neutrons, lifetimes of prompt neutrons, decay constants of delayed neutrons and progenitors of delayed neutrons), peak reactivity, control rod values, neutron power, modes of operation, and the like, with the program including:

- a thermodynamic model that simulates heat transfer from the fuel elements and the effect of said heat on the simulated reactor,

- a physics module that solves the point kinetic equations with fuel temperature and temperature moderator feedbacks for real-time simulation of the reactor core, and said physics module includes:

o a pulsing system that monitors the physical parameters of the pulse and initiates a rapid shutdown of the reactor after the pulse o a control system for controlling the control rods adapted to move the rods between two extreme positions, which position can be determined by the user or by an automatic system that is described below, o calculation of possible core poisoning, which calculates new concentrations of fission products based on the Bateman equations, o calculation of neutron concentration in the next time step, o simulation of the safety system, which monitors thermal power, period, water temperature and fuel temperature, and if necessary initiates a rapid shutdown of the reactor in the event that any of the pre-set threshold values are exceeded, wherein the threshold values can be defined and/or changed by the user, a computer adapted to:

o calculation of all physical quantities of models, o display of simulation information, settings and parameters, such as time dependence of power, reactivity and temperature and display of the position of control rods and other simulator settings, on the screen, o connection to the console and for transmitting signals to the console or console computer,

- a console that acts as an interface between the user and the computer, which is equipped with at least:

- with a connecting means for connecting to a computer,

- with a microcontroller adapted to communicate with a computer and to implement the computer component of the console, which is essentially a loop for exchanging the state of buttons and signals from the computer, and

- with a panel equipped with:

o buttons for controlling the reactor simulation, especially the three control rods, o warning lights, whereby the mentioned buttons and lights are electronically connected to the microcontroller.

The buttons, when lit, generate signals for the following simulations:

- activation of the control rod lifting mechanism;

- lowering the control sticks;

- immediate manual shutdown of the reactor;

- starting the control stick in pulse mode;

- selection of operation mode, which can be automatic, pulse, operation with periodic change of reactivity (sine, saw, steps), or user-defined operation with change of reactivity.

More specifically, the buttons and their functions are as follows:

- "stick up" button • when pressed: if joystick is enabled then moves the joystick and the magnet holding the joystick up • when pressed: if joystick is not enabled then moves the joystick magnet up , but the stick is kept in the fully inserted position, • if the control stick magnet is in the maximum position, then the button light is on, • if the control stick magnet is lower than the maximum position, then the button light is off, "stick down" button:

• when pressed: if joystick is enabled then moves the joystick and the magnet holding the joystick down • when pressed: if joystick is not enabled then moves the joystick magnet down but keeps the stick in the fully inserted position, • if the control rod magnet is in the maximum position, then the button light is on, • if the control rod magnet is lower than the maximum position, then the button light is off, the button to enable the rods:

• when pressed:

• if the bar is disabled:

• SCRAM signals are not triggered: the bar magnet will be activated. If the rod magnet is in the down position, the control rod will start to follow the magnet. The button will light up.

• any SCRAM signal triggers: nothing happens.

• if the bar is enabled:

• the magnet of the rod will be disabled, which will mean that the rod falls into the reactor. The position of the rod will no longer depend on the position of the magnet.

FIRE button:

• when pressed:

• If the reactor is not in pulse mode, it works in the same way as the “enable rod” button for rod regulation, • If the reactor is in pulse mode, it moves the control rod according to the current position of the control rod magnet, the SCRAM button:

• when pressed:

• de-energizes the control stick magnets, causing the control sticks to drop to the fully retracted position, • “MAN” scram light comes on, • all “stick enable” buttons turn off, mode selector button:

• if set to MANUAL, enables manual stick control, • if set to SQ WAVE, enables step mode operation, • if set to SAVVTOOTH, enables sawtooth operation mode, • if set to AUTO, enables automatic mode, • if is set to PULSE, enables pulse mode, "MAN" scram light:

• lights up when the user presses the “SCRAM” button on the console or on the associated user interface on the computer • turns off when the user resets the SCRAM signals with the user interface “POW” scram light:

• turns on when the reactor power exceeds the value set by the user • turns off when the user resets the SCRAM signals with the user interface, “VVTEMP” scram light:

• lights up when the water temperature exceeds the value set by the user • goes out when the user resets the SCRAM signals with the user interface, “FTEMP” scram light:

• lights up when the fuel temperature exceeds the value set by the user • goes out when the user resets the SCRAM signals with the user interface, “PER” scram light:

• turns on when the reactor period exceeds the value set by the user • turns off when the user resets the SCRAM signals with the user interface.

The invention enables adjustments and changes in the parameters of the reactor core, such as the size of the core, kinetic reactor parameters (effective fractions of delayed neutrons, lifetimes of prompt neutrons, decay constants of delayed neutrons and progenitors of delayed neutrons), excess reactivity, values of control rods, neutron powers, etc. The invention allows all physical parameters to be adjusted in a program running on a computer, with the processor and program making all the necessary adjustments based on the physical model and the thermodynamic model, meaning that the simulator can be adjusted for several different research reactors . Therefore, the simulator is general and not tied to a specific type of reactor. Furthermore, the simulator according to the invention can be used as a tool for training students at all levels of nuclear engineering studies, and not only as a tool for training nuclear reactor operators.

The research reactor simulator according to the invention is primarily intended for educational purposes in countries or institutions that do not have easy access to research reactors and for demonstrations of the behavior of nuclear nuclei in the classrooms of educational institutions. The system is realistic, as it allows parameters to be adjusted, as well as fast and flexible due to the thermodynamic model. Furthermore, the console has the same control buttons and warning lights as conventional rectors. As a result, it provides a real experience of operating a nuclear reactor. The number of buttons is few and their functions are clear, so using the simulator is intuitive and easy.

The method of operation of the research reactor simulation system according to the invention includes the following steps:

a) connecting the console to a suitable computer, preferably via USB or any other connection, and running the program on the computer,

b) setting the parameters of the simulated reactor, whereby the program makes all the necessary adjustments according to the physical model,

c) selection of console operation mode,

d) adjusting the control sticks of the console by pressing the up and down buttons, e) simulating the power, temperature, reactivity according to the set mode of operation and the position of the control sticks, and if any parameter is out of bounds, the simulator will turn off as it would reactor and displays a warning signal.

During operation, the control sticks can be reset, the operation mode can be changed, etc., all adjustments being made by the processor and program according to the physical suit. In addition, the simulator allows the user to speed up or slow down the simulation, which allows teachers to demonstrate long-term phenomena such as reactor response to Xe poisoning or reactor response to small, symmetric periodic changes in reactivity.

The present invention will be described in more detail below with the help of examples and pictures showing:

Figure 1: Schematic of the system according to the invention

Figure 2: A possible design of the console panel

Figure 3: Detailed diagram of the simulator components

As shown in Figure 1, the system console is the user interface of the simulator. It includes a board 1 with buttons and warning lights, a microcontroller 3 and an electronic connection 2 for connecting the board 1 and the microcontroller 3. The latter uses a communication means 4 to communicate with a personal computer 5. The communication between the user interface 1 on the console and the personal computer 5 is two-way, as follows:

i. the console sends the status of all buttons and switches to the PC. The signal is sent via the board 1 via connection 2 to the microcontroller 3 in the console and via the communication means 4 to the computer 5 (example: signal transmission by pressing one of the buttons on the user interface).

ii. The console receives signals from the PC about the status of the simulation signals; SCRAM, control stick positions, stick lift mechanism states and mode of operation. The digital signal from the computer 5 travels via the communication means 4 to the console, where it is processed by the microcontroller 3 and accordingly displayed on the board 1 (example: lighting of one of the warning lights on the user interface).

Figure 2 shows a possible embodiment of a console panel that includes buttons 7 adapted to control the movement of the three control rods and additional lights and sound signals 8 and/or warning lights 6 adapted to alert the user of manual or automatic shutdown of the reactor (SCRAM signal) due to exceeding the limit value of the reactor period, fuel temperature, thermal power, cooling water temperature, or manual shutdown. Each control stick has a specific set of three buttons 7, namely “raise”, “lower” and “enable”. Further buttons 7 are: - the FIRE button and - the SCRAM button, whose functions are described above.

The console can additionally include an optional switch for selecting the reactor operation simulation method, namely: - manual mode;

- automatic mode;

- pulse mode;

- method of periodic change of reactivity (sine, saw, step).

In manual mode, the control stick is operated by the user with the up/down buttons. In pulse mode, the user simulates pulse experiments, where one of the control rods is quickly withdrawn from the system, which quickly increases the reactivity.

In automatic mode, the simulator checks if the difference between the current reactor power and the desired reactor power is greater than a pre-set limit value and moves the desired position up or down until the pre-set value condition is met. Sawtooth, sinusoidal, and stepper modes of operation move the joystick to follow waveforms set by the user.

Lights 6 on board 1 are:

- "MAN" scram light,

- "POW" scram light,

- "VVTEMP" scram light,

- "FTEMP" scram light, and

- "PER" scram light whose functions are described above.

Figure 3 shows the precise operation of the reactor components. The modules in the image run from left to right as shown in the image. The first module is the process manager 9, which takes care of the connection between the physical model and the graphical interface and the time synchronization 10. The second module is the physical module, which calculates the time-dependent physical parameters of the simulated reactor. It includes a pulsation system 11, a hydrodynamics calculation 12, a control rod simulator 13, a core poisoning calculation 14, a kinetics calculation 15 and a safety system simulation 16. The simulator then calculates the displayed parameters 17, takes care of reading the user signals 18 and updating the display 19 on the screen. Based on the simulation results, the user interface sends some of the simulation signals to the K console.

Claims (9)

Patent claims 1. A research reactor simulation system based on a reactor having three control rods adapted to control the chain reaction in the simulated reactor and thus its power, said system including: - a computer program that can be executed on a computer, whereby the program is adapted to perform the following: o simulating the behavior of the reactor core, o selecting and/or adjusting the physical parameters of the reactor core, such as, for example, the size of the core, kinetic parameters of the reactor, peak reactivity, values of control rods, neutron power, modes of operation, and the like, wherein said program includes: o a thermodynamic model that simulates the heat transfer from the fuel to the environment and the effect of heat on the simulated reactor, o a physical model for solving point kinetics equations with feedback effects due to changing fuel temperature and reactor temperature for real-time core simulation, which includes: a pulsing system that monitors the physical parameters of the pulse and initiates a rapid shutdown of the reactor after the pulse, a control system for controlling the control rods, which is adapted to move the rods between two extreme positions, which position can be determined by the user or by an automatic system that is described below, calculation of possible core poisoning, which calculates new concentrations of fission products based on the Bateman equations, calculation of neutron concentration in the next time step, simulation of the safety system, which monitors thermal power, period, water temperature and fuel temperature, and if necessary initiates a fast shutdown of the reactor in the event that any of the pre-set limit values are exceeded, whereby the limit values can be defined and/or changed by the user, - computer adapted for: o calculation of all physical quantities of models, o display of simulation information, settings and parameters, such as time dependence of power, reactivity and temperature and display of the position of control rods and other simulator settings, on the screen, o connection to the console and for transmitting signals to the console or console computer, - a console that acts as an interface between the user and the computer, which is equipped with at least: - with the connecting means (2) for connecting to the computer (5), - with plate (1) equipped with: o buttons (7) for controlling the reactor simulation, especially three control sticks, o warning lights (6), - whereby the mentioned buttons (7) and lights (6) are electronically connected to the microcontroller (3), - and a microcontroller (3) adapted to communicate with the computer (5) and adapted to execute the software component of the console, which is basically a loop for exchanging the state of the buttons (7) and signals (6) from the computer (5). 2. A research reactor simulation system according to claim 1, wherein the buttons (7) of the console, when turned on, are adapted to generate a signal for the following simulations: - activation of the mechanism for raising the control rods; - lowering the control sticks; - immediate manual shutdown of the reactor; - starting the control stick in pulse mode; - selection of operation mode, which can be automatic, pulse, operation with periodic change of reactivity, such as sine, saw, steps, or user-defined operation with change of reactivity. 3. A system for simulating a research reactor according to claim 1 or claim 2, where the kinetic parameters of the reactor are the fraction of delayed neutrons and the decay constant. 4. A research reactor simulation system according to any of the preceding claims, where the lights (6) and buttons (7) on the console and their functions are as follows: - "stick up" button • when pressed: if the control stick is enabled, then moves the joystick and the magnet holding the joystick up, • when pressed: if the joystick is not enabled, then the joystick magnet moves up, but the stick is kept in the fully inserted position, • if the joystick magnet is at maximum position, then the button light turns on, • if the control rod magnet is lower than the maximum position, then the button light turns off, - "stick down" button: • when pressed: if joystick is enabled then moves the joystick and the magnet holding the joystick down • when pressed: if joystick is not enabled then moves the joystick magnet down but keeps the stick in the fully inserted position, • if the magnet of the control rod is in the maximum position, then the light of the button turns on, • if the magnet of the control rod is lower than the maximum position, then the light of the button turns off, - button to enable bars: • when pressed: • if the bar is disabled: • SCRAM signals not triggered: the rod magnet will be activated, where if the rod magnet is in the down position, the control rod will start to follow the magnet, and the button will light up, • any SCRAM signal triggered: nothing happens, • if the bar is enabled: • the magnet of the rod will be disabled, which will mean that the rod will fall into the reactor, and the position of the rod will no longer be influenced by the magnet, the FIRE button: • when pressed: • If the reactor is not in pulse mode, it works in the same way as the "enable rod" button for rod regulation, • If the reactor is in pulse mode, it moves the control rod according to the current position of the control rod magnet, the SCRAM button: • when pressed: • de-energizes the control stick magnets, causing the control sticks to drop to the fully retracted position, • “MAN” scram light comes on, • all “stick enable” buttons turn off, mode selector button: • if set to MAN UAL, enables manual stick control, • if set to SQ WAVE, enables step mode, • if set to SAVVTOOTH, enables sawtooth mode, • if set to AUTO, enables automatic mode, • if set to PULSE, enables pulse mode, "MAN" scram light: • lights up when the user presses the “SCRAM” button on the console or on the associated user interface on the computer • turns off when the user resets the SCRAM signals with the user interface “POW” scram light: • turns on when the reactor power exceeds the value set by the user • turns off when the user resets the SCRAM signals with the user interface, - "WTEMP" scram light: • turns on when the water temperature exceeds the value set by the user • turns off when the user resets the SCRAM signals with the user interface, - "FTEMP" scram light: • turns on when the fuel temperature exceeds the value set by the user • turns off when the user resets the SCRAM signals with the user interface, - "PER" scram light: • turns on when the reactor period exceeds the value set by the user, o turns off when the user resets the SCRAM signals with the user interface. 5. A research reactor simulation system according to any of the preceding claims, wherein the console warning lights (6) are adapted to turn on or off when a signal generated by the program is received on the microcontroller (3) or computer (5). 6. A system for simulating a research reactor according to any of the preceding claims, where the console is equipped with a switch for selecting the simulation mode of reactor operation, namely: - manual mode; - automatic mode; - pulse mode; - method of periodically changing reactivity, such as sine, saw, step. 7. A research reactor simulation system according to the preceding claim, wherein - in manual mode, the stick control is controlled by the user with the up/down buttons, - in pulse mode, the user simulates pulse experiments, where one of the control rods is quickly withdrawn from the system, which quickly increases the reactivity, and - in automatic mode, the simulator checks if the difference between the current power of the reactor and the desired power of the reactor is greater than the pre-set limit value and moves the desired position up or down until the condition of the pre-set value is met. 8. A method of operating a research reactor simulation system according to any one of the preceding claims, wherein the method includes the following steps: a) connecting the console to a suitable computer (5), preferably via USB or any other connection, and running the program on the computer (5), b) setting the parameters of the simulated reactor, whereby the program makes all the necessary adjustments according to the physical model, c) selection of console operation mode, d) adjusting the control sticks of the console by pressing the buttons (7) up and down, e) simulation of power, temperature, reactivity according to the set mode of operation and the position of the control rods, whereby if any parameter is out of bounds, the simulator is switched off just like a reactor and a warning signal is displayed. 9. The method according to the preceding claim, where during operation the control rods can be reset, the mode of operation changed and the like, whereby all adjustments are made by the processor and the program in accordance with the physical and thermodynamic model.