modelling incineration of minor actinides in the experimental … · 2005-02-24 · modelling...
TRANSCRIPT
Modelling Incineration of Minor Actinides
in the Experimental ADS MYRRHA
E. Malambu, V. Sobolev, W. Haeck, H. Aït Abderrahim
SCK·CEN, Boeretang 200, Mol, Belgium
February 16-18, 2005ARWIF-2005, Oak Ridge, USA
Contents
1. Introduction
2. Irradiation conditions
3. Fuel targets
4. Results of modelling
5. Conclusions
1.1. Introduction
• High level radioactive waste (HLW) is the problem of a high importance in countries using nuclear energy. About 105 t of HLW are into intermediate storages. 2000 t are produced every year in USA and 2500 t in EU(15).
• Pu, MA (Np, Am, Cm) and some LLFP give major contribution to the long term radiotoxicity. Spent fuel -> 10 kg/t Pu, 1.4 kg/t MA, 1.2 kg/t LLFP.
• P&T allows to reduce significantly the amount and radiotoxicity of HLW going to geological disposal.
• Subcritical ADS can be an effective and safe solution for transmutation of MA and Pu burning.
• The Belgian nuclear research Centre SCK·CEN in collaboration with other countries is developing an experimental ADS (MYRRHA) for MA and LLFP transmutation studies and demonstration.
1.2. Introduction: ADS in double strataADS in double strata
1st strata: Recovered Pu and UEnriched U
Standard fuel fabrication Spent fuel reprocessing
MA, depleted Pu, LLFP
Partitioning
Dedicated fuelfabrication
Short-lived FP +remnant
MA, depleted Pu, LLFP
ReprocessingADS-
transmuter
MA, depleted Pu, LLFP
NPP
2nd strata:
Disposal
1.3. Introduction: MYRRHA ADSMYRRHA ADS
Proton beam line
Subcritical core
Reactor vessel Primary coolant
Spallation loop
Secondary coolant
Main performances:
• Proton source: Ep~350 MeV, Ip~ 5 mA
• Liquid Pb-Bi spallation source and coolant
• Highly enriched MOX in the sub-critical core
• keff limited to ~ 0.95
• Total power ~ 50 MW(th)
• Maximal fast neutron flux ~ 1015 n.cm-2s-1
Proton accelerator
1.4. Introduction: MYRRHA ADS coreMYRRHA ADS core
Experimental channels
Reflector zone
Active zone
Spallation target
Experimental channels
Reflector zone
Active zone
Spallation target
Experimental channels
Reflector zone
Active zone
Spallation target
• 99 + 3 hexagonal cells (“macro-cells”) • Target-block hole is made by 3 removed FA in the central region • Surrounding active zone composed of 45 (or more) FA• Outer reflector zone composed of 54 (or less) reflector assemblies
1.5. Introduction: MYRRHA ADS spectrumMYRRHA ADS spectrum
1.0 E -4
1 .0 E -3
1 .0 E -2
1 .0 E -1
1 .0E + 0
1 .0 E -7 1 .0 E -6 1 .0E -5 1 .0E -4 1 .0 E -3 1 .0 E -2 1 .0 E -1 1 .0 E + 0 1 .0E + 1 1 .0E + 2 1.0 E + 3
N eu tron E n ergy (M eV )
Neu
tron
flux
per
leth
argy
uni
t
L B E -targ etT 91 - w a llF A [1 0 0 ]R efl[1 4 0 ]
1.6. Introduction: MYRRHA ADS fluxMYRRHA ADS flux
2.1. Irradiation conditions:Transmutation core optionTransmutation core option
Coolant. channels with dummy steel rods
LLFP rod bundles
Coolant (opened) channels
U-free MA fuel assemblies
(U-Pu)O2 fuel assemblies
LBE spallation target
Coolant. channels with dummy steel rods
LLFP rod bundles
Coolant (opened) channels
U-free MA fuel assemblies
(U-Pu)O2 fuel assemblies
LBE spallation target
D
D
D
A
A
A
2.2. Irradiation conditions : Neutron spectrum in A and DNeutron spectrum in A and D
1.0E-4
1.0E-3
1.0E-2
1.0E-1
1.0E+0
1.0E-4 1.0E-3 1.0E-2 1.0E-1 1.0E+0 1.0E+1 1.0E+2
Energy (MeV)
Neu
tron
per
leth
argy
uni
t
MAs in A
MAs in D
2.3. Irradiation conditions:Flux regimeFlux regime
0
1
2
3
4
0 120 240 360 480 600 720
Time, d
Tota
l ave
rage
neu
tron
flux,
1015
n c
m-2
s-1
Constant flux regime
Constant beam current
Constant LHGR regime
3. Fuel targets:
Composition:40 vol.% (Cm0.1Am0.5,Pu0.4)O1.88 + 60 vol.% MgO
Density 90 % TDFuel column diameter x height: 5.35 x 40.0 mm
Initial fuel isotopic vectors: 2nd strata option.
AMERICIUMIsotope Content
wt.%241Am 66.67243Am 33.33
PLUTONIUMIsotope Content
wt.%238Pu 5.06239Pu 37.91240Pu 30.31241Pu 13.21242Pu 13.51
CURIUMIsotope Content
wt.%244Cm 90.00245Cm 10.00
4.1. Results of modelling:
• ALEPH code system: MCNPX + NJOY + ORIGEN + JEF 2.2 (mod SCK)
• Calculated features:Neutron flux distribution
Neutron spectrum
Effective cross-sections
Fuel isotopic composition evolution
Power density evolution
4.2. Results of modeling:Pu, Am and Cm contentPu, Am and Cm content
0.7
0.8
0.9
1.0
1.1
1.2
1.3
0 240 480 720 960 1200 1440 1680 1920
Elapsed time (days)
Rel
ativ
e m
ass
(m/m
0)
Pu
Am
Cm
Am + Cm
A
A
A
AD
D
4.3. Results of modeling:Cm, Pu and He generationCm, Pu and He generation
( ) ( ) ( )
( ) ( )
16 162241 242 242 238
141242
90%
10%
h d
ym
Am n Am Cm Pu
Am
τ τ
τ
β α= =−
=
+ → ⎯⎯⎯→ + ⎯⎯⎯⎯→ +
→ ⎯⎯⎯⎯→
( ) ( )10.1 18.1243 244 244 240h yAm n Am Cm Puτ τβ α= =−+ → ⎯⎯⎯⎯→ + ⎯⎯⎯⎯→ +
( )87.7238 234yPu Uτ α=⎯ ⎯ ⎯ ⎯→ +
4.4. Results of modeling:He, Xe and Kr generationHe, Xe and Kr generation
0.0E+00
3.0E-04
6.0E-04
9.0E-04
1.2E-03
1.5E-03
0 240 480 720 960 1200 1440 1680 1920
Elapsed time (days)
gram
-ato
ms o
f gas
per
cm
3
He
Kr
Xe
Storage
4.5. Results of modeling:AmAm--isotopes contentisotopes content
0.0E+00
2.0E-01
4.0E-01
6.0E-01
8.0E-01
1.0E+00
1.2E+00
1.4E+00
0 240 480 720 960 1200 1440 1680
Time, d
Con
tent
, g/c
m³
Am-241Am-242mAm-242Am-243
4.6. Results of modeling:Am isotopic compositionAm isotopic composition
0%
10%
20%
30%
40%
50%
60%
70%
80%
start 1stcycle
2ndcycle
3rdcycle
4thcycle
5thcycle
6thcycle
7thcycle
8thcycle
9thcycle
Storage2 y
Isot
ope
frac
tion
Am-241Am-242mAm-242Am-243
4.7. Results of modeling:Cm-isotopes content
0.0E+00
1.0E-01
2.0E-01
3.0E-01
4.0E-01
0 240 480 720 960 1200 1440 1680
Time, d
Con
tent
, g/c
m³ Cm-242
Cm-243
Cm-244
Cm-245
4.8. Results of modeling:Cm isotopic compositionCm isotopic composition
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
start 1stcycle
2ndcycle
3rdcycle
4thcycle
5thcycle
6thcycle
7thcycle
8thcycle
9thcycle
Storage2 y
Isot
ope
frac
tion
Cm-242Cm-243Cm-244Cm-245
4.9. Results of modeling:PuPu--isotopes contentisotopes content
0.0E+00
1.0E-01
2.0E-01
3.0E-01
4.0E-01
5.0E-01
6.0E-01
0 240 480 720 960 1200 1440 1680
Time, d
Con
tent
, g/c
m³. Pu-238Pu-239Pu-240Pu-241Pu-242
4.10. Results of modeling:Pu isotopic compositionPu isotopic composition
0%
5%
10%
15%
20%
25%
30%
35%
40%
start 1stcycle
2ndcycle
3rdcycle
4thcycle
5thcycle
6thcycle
7thcycle
8thcycle
9thcycle
Storage2 y
Isot
ope
frac
tion Pu-238
Pu-239Pu-240Pu-241Pu-242
4.11. Results of modeling: kk∞∞
1.3
1.4
1.5
1.6
1.7
1.8
0 120 240 360 480 600 720 840 960 1080 1200
Time, d
k inf
mul
tiplic
atio
n fa
ctor
MOX
IMF
4.12. Results of modeling:Actinide mass balanceActinide mass balance
m0(BOL)
t1/2 3A+3D 3 A 3 D 3 A 3 D 3 A 3 D
Pu-238 87.7 y 366 326 333 93 92 229% 232%
Pu-239 2.4·104 y 2744 -493 -479 -35.9% -34.9%Pu-240 6550 y 2194 -15 -14 66 63 4.7% 4.4%Pu-241 14.4 y 956 -179 -174 -27 -29 -43.2% -42.6%Pu-242 3.76·105 y 978 79 87 16.1% 17.8%
Pu 7237 -282 -232 132 120 -4.1% -3.1%
Am-241 433 y 6030 -1025 -915 21 22 -33.3% -29.6%
Am-242 16 h; 141 y 124 131 -2 -2 (122 g) (129 g)
Am-243 7370 y 3014 -419 -359 -27.8% -23.8%
Am 9044 -1319 -1143 19 20 -28.8% -24.8%
Cm-242 162.8 d 107 104 -102 -99 (5.2 g) (5.0 g)
Cm-243 285 y 6.1 5.9 (6.1 g) (5.9 g)
Cm-244 18.1 y 1626 103.7 74.3 -68 -60 4.4% 1.8%
Cm-245 8500 y 180.7 25.9 22.2 28.6% 24.5%
Cm-246 4730 y 5.8 5.6 (5.8 g) (5.6 g)
Cm 1807 249 212 -170 -158 8.7% 5.9%
-19 -18 -15.2% -13.1%
∆m2=m2(EOS)-m1(EOI) (∆m1+∆m2)/m0(BOL)
Mass in grams
All actinides 18088 -1352 -1162
∆m1=m1(EOI)-m(BOL)
5. Conclusions (I)
• Studies of possibilities of the MA transmutation in the subcritical ADS MYRRHA are under way at SCK·CEN.
• A code system ALEPH has been developed for the burnup-depletion calculations in the MYRRHA core, and is under validation and testing.
• The evolution of the composition of CERCER IMF with Cm0.1Am0.5Pu0.4O1.88 fuel and MgO matrix, placed into two different positions of the fast core for 9 operation cycles (810 EFPD) followed by 2 years storage, have been modelled with ALEPH.
5. Conclusions (II)
• The net actinide destruction is 2.55 kg over the initial amount of 18.1 kg. The mass decrease of 26.8 % is observed for Am, whereas a mass increase of 7.3 % for Cm.
• He generated in the MA fuels contributes significantly to the rare gas production during operation as well as in storage and can affect significantly fuel properties.The amount of the produced He is ~ 1.5 times higher than Xe+Kr at the end of irradiation and 2.2 times higher after the storage.
• A more detailed analysis aiming at optimisation of the design of the MA fuel targets and of the burning strategy is in progress.