too rapid for this ADS. The operation efficiency, ε o , is 82.1 % assuming 300 days
operation annually.
Design and transmutation performance are summarized in Table 19.5. Volume
fraction of the inert matrix, ZrN, of the MA-ADS core is 69.8 %, adjusted so that
k-effective at the beginning of the cycle (BOC) of the equilibrium core becomes
0.97. The equilibrium core is obtained after calculating ten cycles of burning,
cooling, and recycling. Volume fraction of the Pu-ADS is more and that of the
Pu+U-ADS is almost the same. The inventory at BOC of the heavy metal in
Table 19.5 is proportional to a one-volume fraction of ZrN. An interesting observation is that the amounts of Pu at BOC are equal among three ADSs, which means U
and MA contribute very little to the criticality before depletion. However, impacts on
the criticality drop after depletion is significant (Fig. 19.3). k eff drop of the MA-ADS
is as small as 1.5 %dk, although others lose 14 %dk even at the equilibrium cycle
around 6,000 days, which means MA is a better fertile than
238
U. The Pu-ADS has a
steeper decrease than Pu+U-ADS because of the absence of
238
U. The huge drop of
the Pu- and Pu+U-ADS is not acceptable in the current design of accelerator and
target for the MA-ADS; the acceptable drop is about 3 %dk in the MA-ADS.
The effective transmutation rate and transmutation half-life are listed at the bottom
of Table 19.5. The half-life of the Pu-ADS is shortest because its specific heat is
twofold larger than others although its cycle efficiency, ε c , is much smaller than others.
19.3.4 Result of six-Batch Core
In the one-batch design in the previous section, k eff drop of Pu ADSs is 14 %dk,
which is too large to be compensated by burnable poison or control rods. As the first
step of design improvement, a multi-batch design is introduced. Theoretically, an
Table 19.5 ADS inventories and transmutation half-life for one-batch design (equilibrium core)
ADS case
MA (Ref.)
Pu
Pu+U
Volume fraction of inert matrix (%)
69.8
87.1
68.1
Core inventory at BOC (t)
U
0.19
0.02
2.62
Pu
1.83
1.84
1.88
MA
2.37
0.25
0.18
Core inventory at EOC (t)
U
0.18
0.02
2.39
Pu
1.79
1.60
1.63
MA
1.92
0.25
0.18
Transmutation, BOC-EOC (t)
U
0.00
0.00
0.23
Pu
0.04
0.24
0.26
MA
0.45
0.00
0.00
Specific heat, h (MW/tHM)
182
380
171
λ tr (/year)
2.28E-02
2.96E-02
2.14E-02
T tr (year)
30.5
23.4
32.5
19 Transmutation Scenarios after Closing Nuclear Power Plants
213
operation annually.
Design and transmutation performance are summarized in Table 19.5. Volume
fraction of the inert matrix, ZrN, of the MA-ADS core is 69.8 %, adjusted so that
k-effective at the beginning of the cycle (BOC) of the equilibrium core becomes
0.97. The equilibrium core is obtained after calculating ten cycles of burning,
cooling, and recycling. Volume fraction of the Pu-ADS is more and that of the
Pu+U-ADS is almost the same. The inventory at BOC of the heavy metal in
Table 19.5 is proportional to a one-volume fraction of ZrN. An interesting observation is that the amounts of Pu at BOC are equal among three ADSs, which means U
and MA contribute very little to the criticality before depletion. However, impacts on
the criticality drop after depletion is significant (Fig. 19.3). k eff drop of the MA-ADS
is as small as 1.5 %dk, although others lose 14 %dk even at the equilibrium cycle
around 6,000 days, which means MA is a better fertile than
238
U. The Pu-ADS has a
steeper decrease than Pu+U-ADS because of the absence of
238
U. The huge drop of
the Pu- and Pu+U-ADS is not acceptable in the current design of accelerator and
target for the MA-ADS; the acceptable drop is about 3 %dk in the MA-ADS.
The effective transmutation rate and transmutation half-life are listed at the bottom
of Table 19.5. The half-life of the Pu-ADS is shortest because its specific heat is
twofold larger than others although its cycle efficiency, ε c , is much smaller than others.
19.3.4 Result of six-Batch Core
In the one-batch design in the previous section, k eff drop of Pu ADSs is 14 %dk,
which is too large to be compensated by burnable poison or control rods. As the first
step of design improvement, a multi-batch design is introduced. Theoretically, an
Table 19.5 ADS inventories and transmutation half-life for one-batch design (equilibrium core)
ADS case
MA (Ref.)
Pu
Pu+U
Volume fraction of inert matrix (%)
69.8
87.1
68.1
Core inventory at BOC (t)
U
0.19
0.02
2.62
Pu
1.83
1.84
1.88
MA
2.37
0.25
0.18
Core inventory at EOC (t)
U
0.18
0.02
2.39
Pu
1.79
1.60
1.63
MA
1.92
0.25
0.18
Transmutation, BOC-EOC (t)
U
0.00
0.00
0.23
Pu
0.04
0.24
0.26
MA
0.45
0.00
0.00
Specific heat, h (MW/tHM)
182
380
171
λ tr (/year)
2.28E-02
2.96E-02
2.14E-02
T tr (year)
30.5
23.4
32.5
19 Transmutation Scenarios after Closing Nuclear Power Plants
213