Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 49 (2016)

Nuclear data study for the development of transmutation technology
S. Ebata,∗1 M. Aikawa,∗1 and S. Imai∗2
Nuclear transmutation is a promising technology
for the disposal of nuclear waste with high-level radioactivity. High-level radioactive waste includes theminor actinides (MA), with Z > 89, and long-lived
ﬁssion products (LLFP). For the reduction of MA,
the accelerator-driven system (ADS) has been studied globally, e.g. J-PARC1) plans to establish an ADS
test facility. However, an eﬀective procedure to reduce LLFP has not been found yet. A major hurdle
to development is the lack of reaction data for LLFP,
especially for reactions induced by a charged particle.
The demands for this data is high, although experiments with a LLFP target have diﬃculties related tothe high radioactivity and chemical instability.
Recent progress at the radioisotope beam facility allows us to utilize LLFP nuclei as the beam. Experiments for the LLFP reaction data with inverse kinematics are performed.2) Activities of our data centre
for the transmutation study are to accumulate relateddata, to distribute them to the public, and to estimate
the physical quantities, through the followings:

The TTY strongly depends on the matter properties, but might be useful data for nuclear engineering,
although the cross section is the most fundamental information. To avoid an experiment with the radioactive target directly, we have suggested a conversion
method between the TTYs of the original reaction system and the inverse kinematics system.4) The method
is based on the common cross section between thesesystems and the energy dissipations of the projectilewhich can be described by the stopping power due tothe target matter properties. The conversion coeﬃcient depends on the incident energy of the projectile,
but we found that it can be replaced by a constantvalue in a high energy region. The method is applied
to more speciﬁc systems considering the kinds of projectile and energy, using the PHITS5) simulation.
The excitation function of the cross section has signiﬁcance for nuclear structure (e.g. radius) and for thequantity reﬂected with matter properties (e.g. TTY).
To measure the excitation function, we propose a simple method, which is the thick-target transmission(T3) method.6) The basic concept of the method is theextension of the ordinary transmission method to thatwith a thick target. In the T3 method, the target has
also the role of beam moderator and its thickness corresponds to the energy of the incident particle. Whileadding a thin target ∆x to the target, we count thenumber I(x) of projectile passed through the target
at each thickness x, and can calculate the interaction
cross section, σInt. (x), from the beam attenuation;• Developing a new data format• Thick-target yield (TTY) for the transmutation• Excitation function of the interaction cross section
The new data format is represented in XML which
is both human- and machine-readable.3) We are conﬁrming its availabilities to store and to search data,
including previous one. The labelling of data is key for
an eﬀective data format. Figure 1 shows the format under development. The outline of the format is almost

σInt. (x) ∝ −completed, although there are practical problems, e.g.
the expression of the reaction formula for inverse kinematics. The detailed rules will be determined in thenear future.
∗2(1)If the LLFP beams can be chosen in the T3 method,the σInt. (x) corresponds to the cross section of transmutation. The availability of the T3 method might bedecided from the competition between eﬀorts to change
the thickness and beam energy.
We report the activities for the nuclear data studyof transmutation, and will carry out them with thecooperation among nuclear data, theorists and experimentalists.
This work was funded by ImPACT Program ofCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).

Fig. 1. The parts of data labelled in the Bibliography.

∗1I(x + ∆x)
1ln.
∆x
I(x)

References
1) http://j-parc.jp/Transmutation/en/index.html
2) H. Wang et al., Phys. Lett. B754, 104 (2016).
3) M. Aikawa et al.,RIKENAccel.Prog.Rep.47, 70 (2014).
4) S. Imai et al., RIKEN Accel. Prog. Rep. 48, 98 (2015).
5) T. Sato et al., J. Nucl. Sci. Technol 50, 913 (2013).
6) M. Aikawa et al., In this report.

Faculty of Science, Hokkaido University
Institute for the Advancement of Higher Education,
Hokkaido University- 89 -