1.4 Conclusion
In this work, the effectiveness of transmutation with laser Compton scattering for
reducing fission products was quantitatively investigated. The transmutation of
137 Cs is effective with photon flux greater than 10
18 /s, which results in 10 %
reduction for 24 h irradiation. However, transmutation with photon flux 2 Â 10
12 /s,
which is achievable with present maximum accelerator systems, is not effective,
and the reduction rate is approximately two orders of magnitude less than the
natural decay rate.
Nuclear transmutation with laser Compton scattering can transmute selectively a
medium mass nuclide
A X into
AÀ1 X, and its reduction rate is independent of
isotopes. Because the transmutation with laser Compton scattering can almost
exclusively generate desired nuclides, this method will be useful for the generation
of isotopes for medicine [1].
1×10
–5
1×10
0
1×10
5
1×10
10
1×10
15
1×10
20
1×10 25
0
5
10
15
20
Number of Cs Isotopes
Irradiation Time (h)
137 Ba generated by Natural Decay of
137 Cs
137 Cs
136 Cs
135 Cs
Fig. 1.6 Number of Cs
isotopes when 1 g
137
Cs is
irradiated with photon flux
2 Â 10
12
/s. Dotted line
shows the number of
137
Ba
that are generated by the
natural decay of 1 g
137
Cs
Table 1.1 Generation rate of
AÀ1
X from 1 g of fission product
A
X with photon flux 2 Â 10
12
/s
Target (
A
X)
[B (n), B (2n)] (MeV)
E GDR (MeV)
σ
tot
GDR (bÁMeV)
N (
AÀ1
X) (/s)
129
I
[8.83, 15.7]
15.3
2.25
1.24 Â 10
10
135
Cs
[8.76, 15.7]
15.2
2.31
1.31 Â 10
10
137
Cs
[8.28, 15.1]
15.1
2.37
1.19 Â 10
10
90
Sr
[7.81, 14.2]
16.7
1.58
4.71 Â 10
9
10
S. Takai and K. Hagino