breed [neutrons neutron] breed [rods rod] globals [ power his-power sma-power control-error proportional integral-part derivative-part control-output colling-water his-control-error ;last controller error used in the derivative part of the PID sma-control-error ] to setup clear-all set-default-shape turtles "circle" set power 0 set control-output 0 set proportional 0 set integral-part 0 set derivative-part 0 set his-control-error [0 0 0 0 0] set his-power [0 0 0 0 0] set sma-power 0 ask patches [nuclear-fuel] reset-ticks end to nuclear-fuel ;; Patch Procedure if (pcolor = black) and (fuel > (random 100)) [set pcolor red] end to release-neutron ; create-neutrons 1 [set color yellow rt (random 360) setxy random-pxcor random-pycor if any? rods-here [die] ] end to rods-in-auto ;button ask neutrons [fd 2 if (sum [count turtles-here] of neighbors > 7 ) [die] if (any? rods-here) [die] if (pcolor = red) [fission] ] controller power-calculation coll-water if not any? neutrons [stop] tick end to rods-in-manual ;button ask neutrons [fd 2 ;if (sum [count turtles-here]of neighbors > 7 ) ;[ die ] if (any? rods-here) [die] if (pcolor = red) [fission] ] power-calculation coll-water tick end to fission ;; Neutron Procedure hatch colling-water [ lt 45 fd 2 ] set power count neutrons end to power-calculation set his-power fput power but-last his-power set sma-power mean his-power end to controller set control-error (power - set-point) set his-control-error fput control-error but-last his-control-error set sma-control-error control-error - (last his-control-error) ;proportional set proportional control-error * control-gain ;integral let integral-sum (control-error * control-gain) / control-integral set integral-part integral-part + integral-sum ;derivative set derivative-part sma-control-error * control-gain * control-derivative ;controller output set control-output (proportional + integral-part + derivative-part) ;controller output calculation if (control-output - count rods > 0) [create-rods control-output - count rods [ set color gray setxy random-pxcor random-pycor] ] if (control-output < 0) [ ifelse (abs control-output > count rods) [ask n-of abs count rods rods [ die ] ] ;kill the remaining rods [ask n-of abs control-output rods [ die ] ] ] end to add-rods ;button create-rods manual-gain [ set color gray setxy random-pxcor random-pycor] end to remove-rods ;button if (count rods > manual-gain) [ask n-of manual-gain rods [ die ] ] end to coll-water if (water < 30.0) [set colling-water 6 ] if (water >= 30.0 and water <= 70) [set colling-water 3] if (water > 70 ) [set colling-water 1] end @#$#@#$#@ GRAPHICS-WINDOW 442 10 813 382 -1 -1 3.0 1 10 1 1 1 0 1 1 1 -60 60 -60 60 0 0 1 ticks 30.0 BUTTON 22 10 85 43 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL 1 BUTTON 21 53 121 86 rods-in-auto rods-in-auto T 1 T OBSERVER NIL NIL NIL NIL 0 BUTTON 207 55 320 88 rods-in-manual rods-in-manual T 1 T OBSERVER NIL NIL NIL NIL 0 BUTTON 117 11 240 44 NIL release-neutron NIL 1 T OBSERVER NIL NIL NIL NIL 1 SLIDER 20 91 192 124 water water 0 100 91.0 1 1 m³/h HORIZONTAL SLIDER 19 127 191 160 fuel fuel 0 50 5.0 1 1 NIL HORIZONTAL PLOT 20 403 813 553 plot 1 NIL NIL 0.0 1500.0 0.0 1500.0 true true "" "" PENS "power" 1.0 0 -2674135 true "" "plot sma-power" "set-point" 1.0 0 -7500403 true "" "plot set-point" SLIDER 19 163 191 196 set-point set-point 0 2000 976.0 1 1 NIL HORIZONTAL SLIDER 19 199 191 232 control-gain control-gain 0 5 1.21 0.01 1 NIL HORIZONTAL SLIDER 19 235 191 268 control-integral control-integral 1 1000 122.0 1 1 NIL HORIZONTAL SLIDER 19 270 191 303 control-derivative control-derivative 0 10 5.0 0.1 1 NIL HORIZONTAL SLIDER 201 91 373 124 manual-gain manual-gain 0 500 41.0 1 1 NIL HORIZONTAL BUTTON 202 128 283 161 NIL add-rods NIL 1 T OBSERVER NIL NIL NIL NIL 1 BUTTON 289 128 391 161 NIL remove-rods NIL 1 T OBSERVER NIL NIL NIL NIL 1 MONITOR 206 195 280 240 NIL sma-power 17 1 11 MONITOR 299 196 371 241 rods count rods 17 1 11 PLOT 199 249 399 399 rods NIL NIL 0.0 10.0 0.0 10.0 true false "" "" PENS "default" 1.0 0 -16777216 true "" "plot count rods" MONITOR 55 333 138 378 NIL colling-water 17 1 11 @#$#@#$#@ ## WHAT IS IT? Nuclear reactor is a machine that produces heat using the nuclear fission. A nuclear reactor is the part responsible to generate steam in a nuclear power plant analogue with a power boiler which can burn oil, gas or other fuel to produce heat and steam. The steam produced in the reactor is used in one or more steam turbine that convert the mechanical energy in electrical energy. One of the benefits of this method over other power generation is that there are no emissions when compared with fossil burning boilers and there are no necessity to flood big areas such as in hydroelectric. Clear disadvantages are the high impact in case of accident, as the famous catastrophes of Chernobyl and Fukushima. Other challenge of this technology is that the part of the nuclear waste needs long time to decay the radioactivity to a level that is not dangerous for the life and environment. In this project I want to show how this technology works using an Agent Based Model to explain the process of a chain reaction, what are the elements used to control it and how can we improve the controllability of this process, using a Proportional Integral Derivative Controller (PID). ## HOW IT WORKS The whole process is based in a chain reaction. The process starts when a neutron is released, then the neutron has a constant speed and when it hits a fuel, it releases other neutrons and release also energy. The control rods are placed inside of the reactor to absorb the free neutrons and keep the reaction under control, avoiding that the numbers of neutrons and energy increases to a point where the reactor was not designed, this in real life would lead to an emergency shutdown. When the control mode is in manual, the operator can define how many rods he wants and insert or retract rods according with the generated energy, in this case the challenge is to reduce the difference between the desired power generation and the real generation. It is quite difficult for the operator to control it well because the constant time of this process is quite short and it can have high variability. With the control in automatic mode, the operator does not need to control the rods, it is controlled automatically by the PID controller. The PID uses the feedback from the energy generation to define how many rods need to be inserted or retracted. ## HOW TO USE IT In order to use the model you can define the amount of fuel, it has a range from 5 to 50. THe first button to press is the setup, it will create all the fuel. Release-neutron must be pressed inorder to release at least one neutron which will initialize the whole chain reation. We have two option to control the reaction: Press the rods-in-manual to start the simulation in manual mode. You should define the manual-gain, when the add-rods or remove-rods button is pressed, the rods are inserted or removed in the amount of the manual-gain Press hte rods-in-auto to start the simulation in auto mode. You should define all the control parameters, such as control-gain, control-integral and control-derivative. Set-point is a variable that is valid for both operation mode and is the set point of the energy generation. The water flow can be increased in order to reduce the speed of the reaction or reduced to let the neutron mode faster inside the reactor An online value in the interface help you to control how the reactor is operating. ## THINGS TO NOTICE See how the energy generation variability changes in manual mode and in automatic mode. ## THINGS TO TRY You can try to change the control-gain, the control-integral and the control-derivative and observe how each parameter has an impact in the process stability and in the average error between setpoint and real value ## EXTENDING THE MODEL There are other components that have an impact in the reaction that can be implemented in the future, e.g. better modelling of the cooling water, it could help in the fidelity of the model. the implementation of a turnine could be also interesting because of a addition of a dead time in the process that would make the process control more challenging for a PID controller ## NETLOGO FEATURES ## RELATED MODELS There are two model in Netlogo that show how a reactor works. one is the Reactor Top DOwn and the second is the Reactor X-Section ## CREDITS AND REFERENCES @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 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260 31 253 31 230 60 206 68 198 75 209 66 228 65 243 82 261 84 268 100 267 103 261 77 239 79 231 100 207 98 196 119 201 143 202 160 195 166 210 172 213 173 238 167 251 160 248 154 265 169 264 178 247 186 240 198 260 200 271 217 271 219 262 207 258 195 230 192 198 210 184 227 164 242 144 259 145 284 151 277 141 293 140 299 134 297 127 273 119 270 105 Polygon -7500403 true true -1 195 14 180 36 166 40 153 53 140 82 131 134 133 159 126 188 115 227 108 236 102 238 98 268 86 269 92 281 87 269 103 269 113 x false 0 Polygon -7500403 true true 270 75 225 30 30 225 75 270 Polygon -7500403 true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 6.0.4 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ setup release-neutron rods-in-auto ticks = 1500 count neutrons sma-power set-point @#$#@#$#@ @#$#@#$#@ default 0.0 -0.2 0 0.0 1.0 0.0 1 1.0 0.0 0.2 0 0.0 1.0 link direction true 0 Line -7500403 true 150 150 90 180 Line -7500403 true 150 150 210 180 @#$#@#$#@ 0 @#$#@#$#@