4th EucheMs chemistry congress

Monday, 27-Aug 2012
s636
chem. Listy 106, s587–s1425 (2012)
Environment and Green Chemistry
Environmental Radiochemistry – fukushima and Chernobyl
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BehAvior of rAdioACtive CeSiuM durinG
inCinerAtion of MuniCiPAL wASteS
ContAMinAted By rAdioACtive fALLout froM
the fuKuShiMA nuCLeAr ACCident
h. KurAMoChi 1 , M. oSAKo 1
1 National Institute for Environmental Studies (NIES),
Center for Materia Cycles and Waste Managemnet Research,
Tsukuba, Japan
In Japan, radioactive contamination was widely spread by
radioactive fallout from explosions of the Fukushima Dai-ichi
Nuclear Plant. Within Kanto and Tohoku regions, therefore, not
only soils and plants but also municipal solid wastes and sewage
sludges were contaminated. Incineration of those wastes has been
performed to reduce their volume and mass since before the
accident. Unfortunately, radioactive cesium in their incineration
ash was highly concentrated compared with untreated wastes. In
this study, the incineration of contaminated municipal solid waste
was investigated in terms of the partitioning behavior of
radioactive cesium between fly and bottom ashes. The
investigation shows that the content of cesium in the fly ash,
which is particulate matter in the flue gas, was much higher than
that in the bottom ash, which is coarse residue left on the grate of
waste incinerators. To understand the difference in the content of
cesium between fly and bottom ashes, we tried to calculate the
thermodynamic equilibrium of the combustion system using a
commercial calculation software (FACTSage). The calculated
result indicated that cesium preferred to form cesium chloride
(CsCl) gas at the combustion temperature, and partially formed
solid aluminosilicate (CsAlSi2O6). We considered that the former
was the major cesium component of the fly ash and the latter was
that of the bottom ash. This consideration was in a good
agreement with the additional examination result on a leaching
test of fly and bottom ashes, in which the fly and bottom ashes
predominantly contained water-soluble and water-insoluble
cesium compounds, respectively. Furthermore, the equilibrium
calculation also indicated that the inorganic component of
combustion waste affected the chemical composition of
incineration ash.
Keywords: Radioactive cesium; Waste incineration;
Contaminated municipal waste; Thermodynamic equilibrium
calculation; Radioactive contamination;
Environmental Radiochemistry – fukushima and Chernobyl
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iMPortAnCe of CheMiCAL SPeCiAtion on the
MoBiLity of rAdioCAeSiuM in the
terreStriAL environMent
e. SteinneS 1 , h. thorrinG 2 , r. GJeLSviK 2 ,
L. SKuterud 2
1 Norwegian University of Science and Technology, Department
of Chemistry, Trondheim, Norway
2 Norwegian Radiation Protection Authority, Environmental
protection, Osteraas, Norway
Norway was one of the countries most seriously affected by
the Chernobyl accident. Radioecological research in Norway after
1986 has emphasized the importance of chemical speciation of
the radionuclides for their behaviour in soil, water, and sediments.
The mobility of 137Cs in boreal soils of Scandinavia with high
organic matter content has shown to be much greater than in the
previously studied agricultural soils with high content of mineral
matter including clay minerals fixing Cs ions strongly. Thus the
uptake of Cs in plants from these soils is much greater than
previously experienced, and strongly dependent on the chemistry
of the soil solution. Particularly high mobility of 137Cs is observed
in southernmost Norway where the soils are more acidified than
elsewhere. Results from repeated nationwide surveys of natural
surface soils show that the decline of 137Cs is greater in coastal
regions than in areas farther inland, probably attributable to much
greater deposition of Mg2+ and Na + in the former areas replacing
Cs ions on soil particle surfaces. This effect appears to be
particularly strong near the southern coast where deposition of
NH 4
4 th EucheMs chemistry congress
+ from transboundary pollution is evident in addition to the
marine cations. The effect of precipitation chemistry on the 137 Cs
mobility is found to decline with time, indicating that the 137 Cs
cations are gradually moving to sites where they are more strongly
bound. Experiments where identical soil columns, containing
137 Cs from Chernobyl and freshly added 134 Cs, are exposed to
precipitation of different quality in amounts corresponding to ten
years of deposition, largely confirm the conclusions from the
repeated soil surveys.
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc