Photon Factory Activity Report 2018 #36 (2019)

BL-27B/2018G567

Local structural analysis of fission products attached to reactor structural materials
Koki Koshigoe1, Isamu Sato1, Haruaki Matsuura1*1
Cooperative Major in Nuclear Energy, Tokyo City University,
1-28-1 Tamazutsumi, Setagaya-ku, Tokyo, 158-8557, Japan
1 Introduction
For decommissioning of the Fukushima Daiichi
Nuclear Power Station, it is necessary to manage thedismantling wastes safely and rationally. In order tounderstand the penetration mechanism of radioactivespecies in the structural materials, the penetration of twotypes of constructive confrontation solution and theEXAFS characterization of species after penetration havebeen carried out, and the variation of the coordination
environment depending on the amount of aggregates has
been identified.

and the interatomic distance, as well as the change in thepenetration depth of Cs.

2 Experiment
EXAFS measurements have been performed on
concrete with different aggregate content that wassubjected to Cs penetration test in High Energy
Accelerator Research Organization Photon Factory BL27B by transmission and fluorescence modes. A concrete
test piece has been immersed in aqueous 1 M CsCl or CsI
solution for 1 day was cut by 2.0 mm from the surface
using sandpaper in each 0.5 mm, and the concrete powder
obtained was focused on the CsLIII absorption edge. We
have compared the structural functions depending on
concrete type and immersed solution.

larger.0.5 mm
larger.1.0 mm
larger.1.5 mm
larger.2.0 mm
finer.0.5 mm
finer.1.0 mm
finer.1.5 mm
finer.2.0 mm

3FT|(k)·k | [arb.unit]

3 Results and Discussion
Figure 1 shows the structural functions of concreteswith different aggregate type, larger and finer aggregates
after immersion test using CsI, and Fig. 2 shows Cs
penetration depth of the concretes with different
aggregate type. As shown in Fig. 1, structural function
has been varied depending on the type of aggregates. In
particular, the peak size of CsI decreases around 4 Å infiner aggregates, which is due to decrease of contributionof CsI molecules. It is conjectured that a gap createdbetween the cement and the aggregate exists and CsI
solutions penetrates through it in the concrete with larger
aggregate, while Cs ions penetrate in the concrete withfiner aggregate. The amount of aggregate is considered tostrongly influence on the evaluation of Cs infiltration intoconcrete.
Moreover, focusing on the peak size of larger and finer
aggregates samples around 2 Å in Fig. 2, which is theinteratomic distance between Cs and O tends to increase
as it gets deeper from the surface. Furthermore, theincrease degree of distance increases in the case of larger
aggregates.
We are planning to do fitting to obtain detailedstructural parameters. In addition to the amount ofaggregate variation, it is thought to be a factor thatinfluences the coordination with oxygen in the concreteFig. 1 Structural functions of concretes with different
aggregate type after immersion test using CsI.

01

23R [Å]456Fig. 2 Structural functions of concretes of different
penetration depths after immersion test using CsI.
References[1]Y.Takahashi et al,Surface science,.34(3),pp.122(2013)* hmatuura@tcu.ac.jp