JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

Study on Stability of Cs·Sr Solvent Impregnate Resin
against Gamma Irradiation
H. Hoshi a) , T. Kikuchi a) , Y. Morita a) and T. Kimura b)
a) Division of Fuels and Materials Engineering, NSED, JAEA,
b) Division of Environment and Radiation Sciences, NSED, JAEA
Minimization of radioactive waste from reprocessing
process of spent nuclear fuel is strongly desired. We have
developed an advanced technology for separation of heat
generating elements (Cs and Sr) from high level waste to
optimize radioactive waste by its characteristics. Recently,
some analogues of calix-crown or crown ether extractant
were reported on specific selectivity for Cs or Sr,
respectively 1,2) . In our previous study, prepared adsorbents
indicated promising ability to separate Cs and Sr from other
typical fission products dissolved in nitric acid solution;
besides they maintained significant selectivity for Cs or Sr
after gamma irradiation. Decreasing ratio of static
adsorption capacity by irradiation was also estimated. In this
work, gamma irradiation effect on dynamic adsorption
capacity was examined for the conceptual designing.
An extractant and a modifier were impregnated into
porous silica, which is embedded styrene divinyl benzene
polymer on the surface. These adsorbents contacting with
nitric acid solution were exposed to gamma ray in a vial.
The dynamic adsorption capacity was examined by using
irradiated adsorbents. The irradiated adsorbent was packed
in a glass column as slurry state. After the packed column
was filled with 3 M HNO 3, a break through curve was
obtained by feeding HNO 3 solution containing 10 mM Cs or
Sr.
Initial dynamic adsorption capacity was estimated in
advance and was 70.2 mmol/L, which was obtained by the
product of Cs concentration and the difference between the
break through point and the dead volume. Figure 1 shows
[Cs] / mM
1-15
10
8
6
4
2
Dead
volume
0
0 10 20 30 40 50 60
Effluent volume / cm 3
54.9 cm 3
Fig. 1 Breakthrough curve of Cs adsorbent after gamma
irradiation. Dose rate: 1.82 kGy/h; duration: 16 h;
Dose: 29.1 kGy; soaked in 3 M HNO3. Column: i.d.
10 mm × 100 mm height (bed height: 82 mm); flow
rate: 1 cm 3 /min; mobile phase: 10 mM Cs-3 M HNO3. JAEA-Review 2010-065
the break through curve of Cs adsorbent, which was
irradiated 29.1 kGy in 3 M HNO 3. The breakthrough point
was estimated at 54.9 cm 3 by linear regression (dotted line).
The dynamic adsorption capacity of irradiated adsorbent
was 73.5 mmol/L, which was almost as same as initial one.
This result indicated that this adsorbent has rather high
stability against gamma irradiation.
Figure 2 shows the break through curve of Sr adsorbent,
which was irradiated 29.1 kGy in 3 M HNO 3. While initial
dynamic adsorption capacity was 125 mmol/L, that of
irradiated adsorbent was 87.1 mmol/L; the dynamic
adsorption capacity decreased by around 30%. Thus, some
refinement of process design will be required.
It is concluded that Cs adsorbent maintained its dynamic
adsorption capacity and Sr adsorbent kept 70% of initial
capacity. Decreasing ratio of dynamic adsorption capacity
by irradiation can be estimated from these results. It
contributes significantly for the conceptual design of
separation plant.
Present study is the result of “Development of separation
technology of transuranium elements and fission products
by using new extractants and adsorbents” entrusted to JAEA
by the Ministry of Education, Culture, Sports, Science and
Technology of Japan (MEXT). We are very grateful to
Mr. Yamagata for his valuable cooperation in this study.
References
1) P. V. Bonnesen et al., Solve. Extr. Ion Exch. 18 (2000)
1079.
2) J. F. Dozol et al., EUR 19605EN, 2000.
[Sr] / mM
- 19 -
10
8
6
4
2
Dead
volume
62.3 cm 3
0
0 10 20 30 40 50 60 70 80
Effluent volume / cm 3
Fig. 2 Breakthrough curve of Sr adsorbent after gamma
irradiation. Dose rate: 1.82 kGy/h; duration: 16 h;
Dose: 29.1 kGy; soaked in 3 M HNO3. Column i.d.:
10 mm × 100 mm height (bed height: 80 mm); flow
rate: 1 cm 3 /min; aq. phase: 10 mM Sr-3 M HNO3.