Fig. 1. Core arrangement of an LFR core
Fig. 2. Geometric structure of fuel assembly
Fig. 3. Calculation models for assembly group constant computation
Fig. 4. Calculation model of an LFR core with Dragon/Donjon code
Fig. 5. Neutron spectrum of UZr fuel in a fuel assembly using Dragon or RMC code
| item | number of
rods in
assembly
| Hexcan outer
flat-to-flat
size/mm
| Hexcan wall
thickness/mm
| pin
pitch/mm
| pin cladding
inner
diameter/mm
| pin cladding
outer
diameter/mm
| pin cladding
thickness/mm
| | fuel assembly | 271 | 173 | 4.5 | 9.80 | 7.37 | 8.500 | 0.565 | | radial reflector assembly | 91 | 173 | 4.5 | 16.90 | — | 15.838 | — | | CR assembly | 31 | 173 | 4.5 | 22.77 | 18.00 | 19.000 | 0.500 | | | | | | | | | | item | pin cladding
outer diameter,
including wrap
wires/mm
| fuel
pellet
outer
diameter/mm
| fuel pellet
inner hole
diameter/mm
| absorber
pellet
diameter/mm
| rod body
outer diameter
of CR
assembly/mm
| rod body
wall thickness
of CR
assembly/mm
| assembly
(section)
axial
length/m
| | fuel assembly | 8.584 | 7.37 | 4.944 | — | — | — | upper reflector section: 0.5
gas chamber section: 1.1
fuel pellet section: 0.9
lower reflector section: 0.5
| | radial reflector assembly | — | — | — | — | — | — | 3.0 | | CR assembly | — | — | — | 17 | 149 | 2 | absorber pellet section:1.0
lower reflector section: 0.5
LBE section: 1.5
|
|
Table 1. Designed dimensions of fuel, radial reflector and control rod assemblies (293 K)
| group
number
| upper energy limit
of 172-group lib/eV
| upper energy limit
of 295-group lib/eV
| | 1 | 19.6400×106 | 19.6400×106 | | 2 | 10.0000×106 | 10.0000×106 | | 3 | 6.0653×106 | 6.0653×106 | | 4 | 3.0119×106 | 3.3287×106 | | 5 | 2.0190×106 | 1.9014×106 | | 6 | 1.2246×106 | 1.2870×106 | | 7 | 8.2085×105 | 8.6001×105 | | 8 | 4.9787×105 | 4.9400×105 | | 9 | 3.0197×105 | 3.2065×105 | | 10 | 1.2277×105 | 1.6506×105 | | 11 | 1.1109×105 | 1.1562×105 | | 12 | 6.7379×104 | 6.7379×104 | | 13 | 3.6979×104 | 3.6979×104 | | 14 | 1.6616×104 | 2.2699×104 | | 15 | 1.5034×104 | 1.4900×104 | | 16 | 9.1188×103 | 9.1188×103 | | 17 | 5.0045×103 | 5.0045×103 | | 18 | 3.3546×103 | 3.4811×103 | | 19 | 1.5073×103 | 1.8118×103 | | 20 | 1.2341×103 | 1.1347×103 | | 21 | 6.7729×102 | 6.7729×102 | | 22 | 3.7170×102 | 4.1909×102 | | 23 | 3.0432×102 | 2.9592×102 | | 24 | 1.3674×102 | 1.4666×102 | | lower energy limit/eV | 1.0000×10−5 |
|
Table 2. 24 group energy structure for condensation
| solution | kinf | | difference with RMC/10−5 | | UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| | RMC code | 1.33254 | 1.35197 | 1.23743 | | — | — | — | | Dragon code (172-group lib) | 1.31722 | 1.33137 | 1.22903 | | −873 | −1144 | −552 | | Dragon code (295-group lib) | 1.31272 | 1.32382 | 1.22524 | | −1133 | −1573 | −804 |
|
Table 3. Calculation results of kinf in an LFR fuel assembly
| solution | reactivity change of coolant density effect, ΔρLBE/10−5 | | relative difference/% | | UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| | RMC code | 265 | 383 | 214 | | — | — | — | | Dragon code (172-group lib) | 247 | 374 | 224 | | −6.8 | −2.3 | 4.7 | | Dragon code (295-group lib) | 248 | 375 | 223 | | −6.4 | −2.1 | 4.2 |
|
Table 4. Calculation results of coolant density effect in an LFR fuel assembly
| solution | fuel Doppler coefficient, kD/10−5 | | relative difference/% | | UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| UZr fuel
assembly
| UPuZr fuel
assembly
| UO2 fuel
assembly
| | RMC code | −297 | −380 | −743 | | — | — | — | | Dragon code (172-group lib) | −280 | −359 | −715 | | −5.7 | −5.5 | −3.8 | | Dragon code (295-group lib) | −300 | −378 | −725 | | 1.0 | −0.5 | −2.4 |
|
Table 5. Calculation results of fuel Doppler coefficient in an LFR fuel assembly
| solution | keff | | difference with RMC/10−5 | | LFR core with
UZr fuel
| LFR core with
UPuZr fuel
| LFR core with
UZr fuel
| LFR core with
UPuZr fuel
| | RMC code | 1.02934 | 1.03132 | | — | — | | 172-group lib | MCFD | 1.04436 | 1.03005 | | 1398 | −120 | | SP3 | 1.03517 | 1.01923 | | 548 | −1151 | | 295-group lib | MCFD | 1.04139 | 1.02432 | | 1124 | −663 | | SP3 | 1.03102 | 1.01247 | | 159 | −1805 |
|
Table 6. keffand its discrepancy of a LFR core using Dragon/Donjon code (293 K)
| solution | CR worth/10−5 | | relative difference/% | | LFR core with
UZr fuel
| LFR core with
UPuZr fuel
| LFR core with
UZr fuel
| LFR core with
UPuZr fuel
| | RMC code | −10570 | −10022 | | — | — | | 172-group lib | MCFD | −10459 | −10250 | | −1.1 | 2.3 | | SP3 | −11056 | −10787 | | 4.6 | 7.6 | | 295-group lib | MCFD | −10405 | −10235 | | −1.6 | 2.1 | | SP3 | −10985 | −10743 | | 3.9 | 7.2 |
|
Table 7. Discrepancy of control rod worth of an LFR core using Dragon/Donjon code
| XS library | method | relative difference of LFR core with UZr fuel/% | | relative difference of LFR core with UPuZr fuel/% | | Max | Min | RMS | Max | Min | RMS | | CR-P and CR-S
withdrawn
| 172-group lib | MCFD | 1.6 | −4.4 | 1.7 | | 1.7 | −4.8 | 1.9 | | SP3 | 5.5 | −1.5 | 1.8 | | 3.9 | −1.3 | 1.4 | | 295-group lib | MCFD | 3.0 | −8.9 | 3.7 | | 2.7 | −8.3 | 3.4 | | SP3 | 1.4 | −3.9 | 1.4 | | 1.3 | −3.7 | 1.3 | | CR-P at critical
location;
CR-S withdrawn
| 172-group lib | MCFD | 3.2 | −5.4 | 2.3 | | 3.1 | −5.9 | 2.4 | | SP3 | 5.1 | −1.7 | 1.7 | | 3.9 | −1.9 | 1.3 | | 295-group lib | MCFD | 4.7 | −9.9 | 4.3 | | 4.3 | −9.2 | 4.0 | | SP3 | 2.2 | −4.7 | 1.9 | | 2.1 | −4.9 | 1.8 |
|
Table 8. Discrepancy of fuel assembly power of an LFR core using Dragon/Donjon code (D/R-1)
