RELAP5 does not contain special input cards for adding the graphite moderator feedback. Consequently, the graphite moderator temperature feedback is calculated in a control system and added to the reactor physics calculation through the additional reactivity cards (30000011 through 30000020). The graphite reactivity versus temperature relationship is obtained from Table 400 based on a constant 6.6x10-4 $/C [ ].
400 Table of Graphite Moderator Feedback
CARD 202TTT00, TABLE TYPE AND MULTIPLIER DATA
Card 20240000
W1(A) TABLE TYPE = reac-t
react-t specifies a table type for reactivity versus time. Although the data in this table does not have to represent reactivity versus time data, it is a common practice to use this option when no units conversion is desired.
CARD 202TTT01 THROUGH 202TTT99, GENERAL TABLE DATA
|
Card Number |
Time after Trip [s] |
Reactivity [$] |
|
20240001 |
0.0 |
0.0 |
|
20240002 |
1000.0 |
6.6 |
LHS graphite reactivity
Next, the graphite reactivity is evaluated. Control functions are written to evaluate the graphite moderator reactivity for all the graphite heat structures.
400 CV-400 = LHS Graphite Moderator Reactivity for Heat Structure 1602001
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20540000
W1(A) ALPHANUMERIC NAME = modfdbk
W2(A) CONTROL COMPONENT TYPE = function
Specifies a function variable. This function variable reads from General Table 400.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 4.42367
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20540001
W1(A) & W2(I) VARIABLE REQUEST CODE V1 = htvat 1602001
Volume average temperature in the LHS graphite blocks, Heat Structure 1602-001
W3(I) GENERAL TABLE NUMBER = 400
General table 400 is read to evaluate the moderator feedback at this graphite temperature.
Control Variables 401 through 413 are identical to Control Variable 400 except successively higher (higher physical location in the core) graphite heat structures are used. For example, Control Variable 401 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 1602002, Control Variable 402 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 1602003, etc.
RHS Channel 1 graphite reactivity
414 CV-414 = RHS (Channel 1) Graphite Moderator Reactivity for Heat Structure 5602001
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20541400
W1(A) ALPHANUMERIC NAME = modfdbk
W2(A) CONTROL COMPONENT TYPE = function
Specifies a function variable. This function variable reads from General Table 400.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 4.42509
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20541401
W1(A) & W2(I) VARIABLE REQUEST CODE V1 = htvat 5602001
Volume average temperature in the RHS Channel 1 graphite blocks.
W3(I) GENERAL TABLE NUMBER = 400
General table 400 is read to evaluate the moderator feedback at this graphite temperature.
Control Variables 415 through 427 are identical to Control Variable 414 except successively higher (higher physical location in the core) graphite heat structures are used. For example, Control Variable 415 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 5602002, Control Variable 416 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 5602003, etc.
RHS Channel 2 graphite reactivity
428 CV-428 = RHS (Channel 2) Graphite Moderator Reactivity for Heat Structure 66020012
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20542800
W1(A) ALPHANUMERIC NAME = modfdbk
W2(A) CONTROL COMPONENT TYPE = function
Specifies a function variable. This function variable reads from General Table 400.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 4.4241
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20542801
W1(A) & W2(I) VARIABLE REQUEST CODE V1 = htvat 6602001
Volume average temperature in the RHS Channel 2 graphite blocks.
W3(I) GENERAL TABLE NUMBER = 400
General table 400 is read to evaluate the moderator feedback at this graphite temperature.
Control Variables 429 through 441 are identical to Control Variable 428 except successively higher (higher physical location in the core) graphite heat structures are used. For example, Control Variable 428 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 6602002, Control Variable 429 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 6602003, etc.
RHS Channel 3 graphite reactivity
474 CV-474 = RHS (Channel 3) Graphite Moderator Reactivity for Heat Structure 76020012
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20547400
W1(A) ALPHANUMERIC NAME = modfdbk
W2(A) CONTROL COMPONENT TYPE = function
Specifies a function variable. This function variable reads from General Table 400.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 4.86813
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20547401
W1(A) & W2(I) VARIABLE REQUEST CODE V1 = htvat 7602001
Volume average temperature in the RHS Channel 3 graphite blocks.
W3(I) GENERAL TABLE NUMBER = 400
General table 400 is read to evaluate the moderator feedback at this graphite temperature.
Control Variables 475 through 487 are identical to Control Variable 474 except successively higher (higher physical location in the core) graphite heat structures are used. For example, Control Variable 474 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 7602002, Control Variable 475 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 7602003, etc.
RHS Channel 4 graphite reactivity
488 CV-488 = RHS (Channel 4) Graphite Moderator Reactivity for Heat Structure 86020012
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20548800
W1(A) ALPHANUMERIC NAME = modfdbk
W2(A) CONTROL COMPONENT TYPE = function
Specifies a function variable. This function variable reads from General Table 400.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 3.95536
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20548801
W1(A) & W2(I) VARIABLE REQUEST CODE V1 = htvat 8602001
Volume average temperature in the RHS Channel 4 graphite blocks.
W3(I) GENERAL TABLE NUMBER = 400
General table 400 is read to evaluate the moderator feedback at this graphite temperature.
Control Variables 489 through 501 are identical to Control Variable 488 except successively higher (higher physical location in the core) graphite heat structures are used. For example, Control Variable 488 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 8602002, Control Variable 489 evaluates the graphite moderator reactivity based on the average graphite temperature in heat structure 8602003, etc.
Total LHS graphite reactivity
The individual LHS graphite reactivities are evaluated and summed together. The weighing functions are based on power squared weighing on the axial power profile.
450 CV-450 = Sum of the LHS moderator reactivities.
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545000
W1(A) ALPHANUMERIC NAME = lhs_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
50% of the total graphite power.
W4(R) INITIAL VALUE = 2.509743
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545001
W1(R) ADDITIVE CONSTANT = See below.
W2(R) GAIN FOR V1 = See below.
Obtained from [ ]
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = See below.
Total fission and decay power to the graphite blocks.
|
Card Number |
Additive Constant |
Gain Factor |
Control Variable |
|
20545001 |
0.0 |
0.027718 |
cntrlvar 400 |
|
20545002 |
0.035009 |
cntrlvar 401 |
|
|
20545003 |
0.039701 |
cntrlvar 402 |
|
|
20545004 |
0.043382 |
cntrlvar 403 |
|
|
20545005 |
0.045078 |
cntrlvar 404 |
|
|
20545006 |
0.045078 |
cntrlvar 405 |
|
|
20545007 |
0.043923 |
cntrlvar 406 |
|
|
20545008 |
0.042227 |
cntrlvar 407 |
|
|
20545009 |
0.040422 |
cntrlvar 408 |
|
|
20545010 |
0.038329 |
cntrlvar 409 |
|
|
20545011 |
0.035009 |
cntrlvar 410 |
|
|
20545012 |
0.029703 |
cntrlvar 411 |
|
|
20545013 |
0.022016 |
cntrlvar 412 |
|
|
20545014 |
0.012405 |
cntrlvar 413 |
|
|
0.500000 |
Total RHS Channel 1 graphite reactivity
The individual RHS Channel 1 graphite reactivities are evaluated and summed together. The weighing functions are based on power squared weighing on the axial power profile.
451 CV-451 = Sum of the RHS Channel 1 moderator reactivities.
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545100
W1(A) ALPHANUMERIC NAME = rhs1_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
50% of the total graphite power.
W4(R) INITIAL VALUE = 2.38017
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545101
W1(R) ADDITIVE CONSTANT = See below.
W2(R) GAIN FOR V1 = See below.
Obtained from [ ]
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = See below.
Total fission and decay power to the graphite blocks.
|
Card Number |
Additive Constant |
Gain Factor |
Control Variable |
|
20545101 |
0.0 |
0.026289 |
cntrlvar 414 |
|
20545102 |
0.033204 |
cntrlvar 415 |
|
|
20545103 |
0.037654 |
cntrlvar 416 |
|
|
20545104 |
0.041145 |
cntrlvar 417 |
|
|
20545105 |
0.042754 |
cntrlvar 418 |
|
|
20545106 |
0.042754 |
cntrlvar 419 |
|
|
20545107 |
0.041659 |
cntrlvar 420 |
|
|
20545108 |
0.040049 |
cntrlvar 421 |
|
|
20545109 |
0.038338 |
cntrlvar 422 |
|
|
20545110 |
0.036352 |
cntrlvar 423 |
|
|
20545111 |
0.033203 |
cntrlvar 424 |
|
|
20545112 |
0.028171 |
cntrlvar 425 |
|
|
20545113 |
0.020880 |
cntrlvar 426 |
|
|
20545114 |
0.011765 |
cntrlvar 427 |
|
|
0.474223 |
|||
Total RHS Channel 2 graphite reactivity
The individual RHS Channel 2 graphite reactivities are evaluated and summed together. The weighing functions are based on power squared weighing on the axial power profile.
452 CV-452 = Sum of the RHS Channel 2 moderator reactivities.
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545200
W1(A) ALPHANUMERIC NAME = rhs2_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
50% of the total graphite power.
W4(R) INITIAL VALUE = 0.1239276
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545201
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = See below.
Obtained from [ ]
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = See below.
Total fission and decay power to the graphite blocks.
|
Card Number |
Additive Constant |
Gain Factor |
Control Variable |
|
20545201 |
0.0 |
0.0013678 |
cntrlvar 428 |
|
20545202 |
0.0017276 |
cntrlvar 429 |
|
|
20545203 |
0.0019591 |
cntrlvar 430 |
|
|
20545204 |
0.0021408 |
cntrlvar 431 |
|
|
20545205 |
0.0022245 |
cntrlvar 432 |
|
|
20545206 |
0.0022245 |
cntrlvar 433 |
|
|
20545207 |
0.0021675 |
cntrlvar 434 |
|
|
20545208 |
0.0020838 |
cntrlvar 435 |
|
|
20545209 |
0.0019947 |
cntrlvar 436 |
|
|
20545210 |
0.0018914 |
cntrlvar 437 |
|
|
20545211 |
0.0017276 |
cntrlvar 438 |
|
|
20545212 |
0.0014658 |
cntrlvar 439 |
|
|
20545213 |
0.0010864 |
cntrlvar 440 |
|
|
20545214 |
0.0006121 |
cntrlvar 441 |
|
|
0.0246740 |
|||
Total RHS Channel 3 graphite reactivity
The individual RHS Channel 3 graphite reactivities are evaluated and summed together. The weighing functions are based on power squared weighing on the axial power profile.
511 CV-511 = Sum of the RHS Channel 3 moderator reactivities.
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20551100
W1(A) ALPHANUMERIC NAME = rhs4_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
50% of the total graphite power.
W4(R) INITIAL VALUE = 0.00504952
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20551101
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = See below.
Obtained from [ ]
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = See below.
Total fission and decay power to the graphite blocks.
|
Card Number |
Additive Constant |
Gain Factor |
Control Variable |
|
20551101 |
0.0 |
4.9497e-6 |
cntrlvar 474 |
|
20551102 |
6.2515e-5 |
cntrlvar 475 |
|
|
20551103 |
7.0894e-5 |
cntrlvar 476 |
|
|
20551104 |
7.7468e-5 |
cntrlvar 477 |
|
|
20551105 |
8.0497e-5 |
cntrlvar 478 |
|
|
20551106 |
8.0497e-5 |
cntrlvar 479 |
|
|
20551107 |
7.8434e-5 |
cntrlvar 480 |
|
|
20551108 |
7.5405e-5 |
cntrlvar 481 |
|
|
20551109 |
7.2183e-5 |
cntrlvar 482 |
|
|
20551110 |
6.8445e-5 |
cntrlvar 483 |
|
|
20551111 |
6.2515e-5 |
cntrlvar 484 |
|
|
20551112 |
5.3041e-5 |
cntrlvar 485 |
|
|
20551113 |
3.9314e-5 |
cntrlvar 486 |
|
|
20551114 |
2.2152e-5 |
cntrlvar 487 |
|
|
8.9286e-4 |
|||
Total RHS Channel 4 graphite reactivity
The individual RHS Channel 4 graphite reactivities are evaluated and summed together. The weighing functions are based on power squared weighing on the axial power profile.
512 CV-512 = Sum of the RHS Channel 4 moderator reactivities.
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20551200
W1(A) ALPHANUMERIC NAME = rhs5_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
50% of the total graphite power.
W4(R) INITIAL VALUE = 9.0149e-4
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20551201
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = See below.
Obtained from [ ]
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = See below.
Total fission and decay power to the graphite blocks.
|
Card Number |
Additive Constant |
Gain Factor |
Control Variable |
|
20551201 |
0.0 |
1.1615e-5 |
cntrlvar 488 |
|
20551202 |
1.4670e-5 |
cntrlvar 489 |
|
|
20551203 |
1.6636e-5 |
cntrlvar 490 |
|
|
20551204 |
1.8179e-5 |
cntrlvar 491 |
|
|
20551205 |
1.8890e-5 |
cntrlvar 492 |
|
|
20551206 |
1.8890e-5 |
cntrlvar 493 |
|
|
20551207 |
1.8406e-5 |
cntrlvar 494 |
|
|
20551208 |
1.7695e-5 |
cntrlvar 495 |
|
|
20551209 |
1.6939e-5 |
cntrlvar 496 |
|
|
20551210 |
1.6062e-5 |
cntrlvar 497 |
|
|
20551211 |
1.4670e-5 |
cntrlvar 498 |
|
|
20551212 |
1.2447e-5 |
cntrlvar 499 |
|
|
20551213 |
9.2257e-6 |
cntrlvar 500 |
|
|
20551214 |
5.1983e-6 |
cntrlvar 501 |
|
|
2.0952e-4 |
|||
Change in Moderator Reactivity
RELAP5 calculates a bias reactivity at the initiation of the problem to make keff = 1.0 at the user specified power. Subsequently, changes in reactivity are evaluated to calculate the change in core power. Consequently, it is the change in moderator reactivity rather than the absolute value of the moderator reactivity that is significant. The change in the moderator reactivity is calculated as follows
453 CV-453 = rmoderator = rLHS moderator + rRHS 1 moderator + rRHS 2 moderator
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545300
W1(A) ALPHANUMERIC NAME = new_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 5.01979
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545301
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = 1.0
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = cntrlvar 450
Absolute moderator reactivity for the LHS
Card 20545302
W1(R) GAIN FOR V1 = 1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 451
Absolute moderator reactivity for the RHS 1 core channels
Card 20545303
W1(R) GAIN FOR V1 = 1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 452
Absolute moderator reactivity for the RHS 2 core channels
Card 20545304
W1(R) GAIN FOR V1 = 1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 511
Absolute moderator reactivity for the RHS 3 core channels
Card 20545305
W1(R) GAIN FOR V1 = 1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 512
Absolute moderator reactivity for the RHS 4 core channels
454 CV-454 = D rmoderator = rmoderatorn + rmoderatorn-1
where,
rmoderatorn - current moderator reactivity
rmoderatorn-1 - previous timestep moderator reactivity
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545400
W1(A) ALPHANUMERIC NAME = delt_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 1.203454e-7
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545401
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = 1.0
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = cntrlvar 453
Current timestep moderator reactivity
Card 20545402
W1(R) GAIN FOR V1 = -1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 455
Previous timestep moderator reactivity
455 CV-455 = Control Variable 453 (old time moderator reactivity)
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545500
W1(A) ALPHANUMERIC NAME = old_mod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 5.01979
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545501
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = 1.0
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = cntrlvar 453
Current timestep moderator reactivity
456 CV-456 = Graphite moderator reactivity
CARD 205CCC00, CONTROL COMPONENT TYPE CARD
Card 20545600
W1(A) ALPHANUMERIC NAME = graphmod
W2(A) CONTROL COMPONENT TYPE = sum
Specifies a sum variable.
W3(R) SCALING FACTOR = 1.0
W4(R) INITIAL VALUE = 0.01046287
Initial conditions established after steady state simulation.
W5(I) INITIAL VALUE FLAG = 0
Zero means no initial value calculation and W4 is used as the initial condition.
CARD 205CCCXX, CONTROL COMPONENT DATA CARDS
Card 20545601
W1(R) ADDITIVE CONSTANT = 0.0
W2(R) GAIN FOR V1 = 1.0
W3(A) & W4(I) VARIABLE REQUEST CODE V1 = cntrlvar 454
Change in moderator reactivity
Card 20545602
W1(R) GAIN FOR V1 = 1.0
W2(A) & W3(I) VARIABLE REQUEST CODE V1 = cntrlvar 456
Previous timestep graphite moderator reactivity