Report on “Radiation Disaster Recovery Studies”
Course’ Environmental Radioactivity Protection
Name; Wiseman Chisale Bekelesi○Regarding“Radiation Disaster Recovery Studies”（Describe your thoughts, the process you engaged in and your research progress regarding Recovery from
Radiation Disaster. ）Fukushima Daiichi Nuclear Power Plant accident occurred in March, 2011. We noted with great
concern that the Fukushima nuclear disaster and radiation protection measures introduced during
recovery phases brought significant consequences for the daily life of the afflicted people. For example,
the people had to be reallocated with strict measures and restrictions on foods which made their lives
difficult. The media was also flooded with lots of information which ought to be scrutinized properly
as some added anxiety to the people. Affected people also needed medical attention and examination
for radiation doses.
Therefore, through the Hiroshima University Phoenix Leader Education Program (HiroshimaInitiative) for the “Renaissance from Radiation Disaster”, which was initially funded by the Ministryof Education, Culture, Sports, Science and Technology came up with a worthwhile program fosteringsocial recovery, environmental radioactivity protection and radiation disaster medicine for not only
the people of Fukushima but also in preparation for the future unforeseeable nuclear disasters.
Throughout my studies at Hiroshima university, I have been exposed to all these three
disciplines with much emphasis on my major, Environmental radioactivity protection which was alsoaffiliated to graduate school of science-chemistry department.
This is the course that has been preparing the scientists how they can deal with radiation
catastrophe emanating from natural disasters, even nuclear terrorist attacks. Frankly speaking, I didenjoy this program in that we have had opportunities of hands-on instrumentation in our researchwork and also, we had a lot of education tours during leadership seminars, conferences and field-work
visits where we shared knowledge with experts in the field. We had social recovery gatherings withthe people of Fukushima in which we discussed a number of issues as regards radiation levels inFukushima and also measured the radioactivity of their foods publicly using portable gamma
spectrometer. This reduced panic among the people as they saw for themselves how the radioactivity
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levels in foods had dropped with time. Above all in this program I accumulated a combination of
global skills, management and interdisciplinary skills by encountering with experts in various fields.
We realized lessons that were learned from the Chernobyl disaster had also to be applied to ourprogram for Fukushima nuclear disaster residents. Environmental radioactivity protection program
dealt much more mitigation measures to deal with anthropogenic radionuclides aftermath of nuclear
disaster in particular 90Sr, 134+137Cs and 131I. The half lives of 90Sr, 134Cs and 137Cs are 28.8, 2.1, and30.1 years, respectively. Iodine-131 has a shorter half-life of 8 days and soon after the disaster muchemphasis had been put on it because it accumulates in thyroid gland. Thus, in order to ensure thatpeople were safe in Fukushima we took initiative of venturing into field sampling in Kawauchi village
and Fukushima city where we collected soil and rice samples from disturbed and undisturbed forestry
and paddies. Further, to ensure that people were consuming rice free of radioactivity we had todetermine the transfer factor, i.e. the ratio of amount of radiocesium transferred to the rice plant tothat in soil. We had also studied critically why the transfer factors between Kawauchi and Fukushima
City paddies were different by looking into other physical and chemical properties of soils in the twoareas. Next, we did really collaborate with the University of Tokyo as long-term internship to analyze
the soil core and bulk samples in Kawauchi village and Fukushima city for distinction in migration
between 137Cs and 90Sr, more particularly in undisturbed forestry, lake sediment and disturbed
paddies.
The results were indeed compelling, Kawauchi soil despite having lower concentration of 137Cs
in its soil, it showed 5-fold transfer factor than that of Fukushima. And there was a difference inmigration between 137Cs and 90Sr.
We believe this information can easily be disseminated to the people through social recovery
sensitization programs now that the levels of radioactivity are on their decline although forests arestill containing high levels of radioactivity. The results of this research together with other findings
concerning the lowering of levels of radioactivity in the arable land of Fukushima has given hope tothe displaced people of Fukushima who have so far sought to return to their abandoned areas.
Above all the course on environmental radioactivity protection prepared me to become aspecialist in environmental radiation protection emergency preparation and response.

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○Title of Doctoral Thesis;
Difference in Migration of Radioactive Element Originating from Fukushima Daiichi Nuclear Power
Plant Accident: Factors affecting transfer factor of 137Cs from soil to rice and Difference in migration
between 137Cs and 90Sr in the Environment○Summary of Doctoral Thesis（Describe so as to be easily understood, by relating it to “Radiation Disaster Recovery Studies”.）
In my doctoral research the focus has been on 137Cs and 90Sr in Kawauchi village and Fukushimacity. This is because both these radionuclides are produced in high yield during nuclear fission
reactions inside core of nuclear reactor. Thus, they are common in radioactive wastes and are present
in the environment following Chernobyl and Fukushima nuclear disasters. 90Sr concentration wasabout 1/1000 that of 137Cs in the soil after FDNPP disaster. The gamma and beta radiation emitted
by the radioactive decay of 137Cs and 90Sr have to be taken into consideration as they may damage thecells of living organisms leading to cancers.
Strontium-90 will be accumulated in the bone and its biological half-life is about 50 years, thus
it is of concern just like 137Cs which affects the whole body although it has a shorter biological halflife of 70-100 days compared to 90Sr. The study of distribution and migration of both nuclides isimportant from the point of protection against external and internal exposure. The present Doctor ofScience (DSc) thesis includes two topics. The first I considered the factors to control transfer factor(TF) of 137Cs from soil to rice plant (First paper). The second I investigated the difference indistribution and migration of 137Cs and 90Sr in the soils of Kawauchi and Fukushima (Second paper).
In the first paper the relation among soil characteristics (soil particle size distribution,exchangeable cation, 137Cs, and 40K, mineral composition, Fe oxidation state and 137Cs transfer factor)
was investigated by analyzing the soil and rice samples from Fukushima City and Kawauchi Village.
This study ensured the comparison of two study areas unlike other studies which have only focusedon one particular area.
The samples were prepared accordingly and analyzed by High Purity Germanium detector. In
order to investigate other physico-chemical properties of the soils following variation in TF between
the two areas. The major exchangeable cations were analyzed by using Inductively Coupled PlasmaAtomic Emission Spectrometry (ICP-AES) after extraction using ammonium acetate, crystal natureof the soils was studied by X-ray diffractometry, while the effect of Fe(II) and Fe(III) on the uptake of137Cs was done by Mössbauer spectroscopy. We also investigated the particle size distribution of thesoils in relation to 137Cs sorption by plants.
Cesium-137 transfer factor between Kawauchi and Fukushima samples was compared. The TFof 137Cs was higher in Kawauchi paddy field compared to that of Fukushima despite the soils ofFukushima being more radioactive than that of Kawauchi.
Cesium-137 was also compared in Fukushima and Kawauchi soils before and after treatment
with 1M ammonium acetate at pH 7. From this, exchangeable 137Cs was obtained for both soils. ThePage 3 of 6amount of exchangeable 137Cs was larger in Fukushima paddy than in Kawauchi paddy. The
percentage (%) of exchangeable 137Cs to total 137Cs was higher in Kawauchi paddy than Fukushima
paddy. On the other hand, % of exchangeable K+ was higher in Fukushima paddy than in Kawauchi
paddy. The results revealed that TF becomes higher when % of 137Cs is higher, while it is restricted
when % of exchangeable K+ is high.
Furthermore, it was shown that Kawauchi soil contains more silt and clay and less coarse andgravel than Fukushima soil. However, Kawauchi soil that contains more silt and clay has higher
percentage of exchangeable 137Cs than Fukushima soil that contains more fine and medium sands.
The finding in this study showed that the 137Cs exchangeable rate cannot be easily explained only
based on the soil particle size distribution.
The analysis of powder X-ray diffraction pattern (PXRD) using Match software showed thatKawauchi soil contains more quartz constituents and slightly less mica minerals than Fukushimasoil and Fukushima soil contains more vermiculite, zeolite and phlogopite. Fukushima soil 137Cs isadsorbed to the clay particles more strongly compared to Kawauchi probably because Fukushima soil
is rich in vermiculite, mica and zeolite which possibly retard 137Cs transfer from the soil to rice plant.
Mössbauer spectra did not show significant magnetic component in Kawauchi soil compared tothat in Fukushima. The ratio of Fe(II)/(Fe(III) + Fe(II)) of Kawauchi soil happened to be larger thanthat of other Fukushima soils. The differences between Fe (II) and Fe (III) signify the influence of theredox potential of the soil. Other studies have shown that microbially mediated reduction of Fe(III)in chlorite and biotite by Shewannella oneidensis MR-1 leads a significant reduction in sorption ofboth Cs and Sr compared to the abiotic system
In the second paper, the difference in distribution and migration between 90Sr and 137Cs in thesoil of disturbed area, Kawauchi (KP) and Fukushima paddy rice fields (FP), and undisturbed area,
Lake Ogi valley sediments (LS) and its catchment forestry area (CA), was investigated. The sediment
to soil ratio for 90Sr and 137Cs was used to analyze the horizontal migration difference between 90Srand 137Cs.
90Sr and 137Cs distributions were investigated by analyzing their concentration in the soil ofKawauchi (KP) and Fukushima paddy rice fields (FP), and the depth distribution of 90Sr and 137Cs in
Lake Ogi valley sediments (LS) and its forestry catchment area soil (CA) and the sediment to soilratio were also investigated. 90Sr is a pure β-emitter and its daughter nuclide (90Y) is also radioactive.
90Sr was extracted from the soil and after the radioactive equilibrium was attained, the radioactivity

was measured using liquid scintillation counter. The recovery ratio was measured promptly by
Inductively Coupled Plasma-Mass Spectrometry-Triple Quadrupole (ICP-MS-QQQ).
The rough correlation between 90Sr and 137Cs concentrations was observed. The relation deviatesfrom original point (0, 0), which suggests the global fallout of 90Sr. The coefficient of variation for 90Sr
was larger than that of 137Cs for Fukushima and Kawauchi paddy. Furthermore, the coefficient ofvariation for 90Sr was also larger than that of 137Cs for Ogi Lake Sediment (LS) and its catchment
forestry area (CA). The results suggest that the migration of 90Sr is more affected by external factor.
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The sediment to soil ratio (LS/CA ratio) of 90Sr was greater than that of 137Cs, which might relate
to 90Sr faster horizontal migration than 137Cs.
The depth dependence of 90Sr and 137Cs at Catchment Forestry area was investigated. Cesium137 and 90Sr activity concentrations decrease exponentially with depth. However, the vertical profile
between the two is different, which showed faster 90Sr vertical migration than 137Cs.

Depth

dependence of 137Cs and 90Sr at Lake Ogi sediments (LS) revealed that the exponential change forboth 137Cs and 90Sr was largely interfered near the surface (0 to 4 cm) for the sediment. One of thepossibilities is that surface sediments become relatively uniform by the disturbance near surface (0~4cm). 137Cs adsorbed strongly to sediment becomes uniform, while 90Sr weakly adsorbed to sedimentre-dissolves to the lake water. The re-dissolved 90Sr is absorbed to the sediment again (0~1 cm).
Therefore, the surface sediment (0~1 cm) has significantly higher 90Sr than that of deeper sedimentlayer.
Strontium-90 penetrated more than 137Cs in the soils of catchment forest and LS/CA ratio of 90Sr
is greater than the LS/CA ratio of 137Cs, which might relate to 90Sr faster horizontal migration than137Cs. The 90Sr/137Cs ratio for Fukushima soil and sediment samples ranged from 0.0001 to 0.0019

with an average value of 0.0007±0.0005, which is in good agreement with some previous results.
In conclusion there was a difference in migration between 137Cs and 90Sr. However, in future
research there is need to take core soil samples from the paddies also in order to compare well withthe core samples from undisturbed forestry zones. Further, considering 5 folds values TF of Kawauchi
compared to that of Fukushima, it is vital in future research to consider also how 137Cs transfer factor
might be influenced by the adsorption kinetics.
○Other theses published in academic research journals
・Title of academic research journals（Impact Factor, Peer Review）
1. W.C. Bekelesi, T. Basuki, S. Nakashima,137Cs Soil to Rice Transfer Factor and Soil Properties:
Fukushima and Kawauchi Case Study. Radiation Safety Management Vol. 21 (1–12) (2022).
[doi:10.12950/rsm.220131].
2. W.C. Bekelesi, T. Basuki, S. Higaki, S. Nakashima, Distinction of strontium-90 and cesium-137
migration of Fukushima soil and sediment following Fukushima accident. Radiation Safety
Management Vol. 21 (26–35) (2022).[doi:10.12950/rsm.220527].
・Title of thesis
1. W.C. Bekelesi, E.O. Darko, A.B. Andam, Activity concentrations and dose assessment of 226Ra,228Ra, 232Th, 40K, 222Rn and 220Rn in soil samples from Newmont-Akyem gold mine using
gamma-ray spectrometry. African Journal of Environmental Science and Technology. 2017 May
31;11(5):237-47. https://academicjournals.org/journal/AJEST/article-abstract/759E8E064123
2. W.C. Bekelesi. Thesis, Master of Philosophy Degree (2015).
http://ugspace.ug.edu.gh/handle/123456789/8571.

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・Joint authors
1. T. Basuki, W. C. Bekelesi, M. Tsujimoto, S. Nakashima, Air dose rate to 137Cs activity per unit
area ratio for different land use 7 years after the nuclear accident -Case of the slope catchment,
Ogi reservoir, Fukushima-, Radiation Managements, 137 (2020).
https://doi.org/10.1016/j.radmeas.2020.106424.
2. T. Basuki, W. C. Bekelesi, M. Tsujimoto, S. Nakashima, Investigation of radiocesium migrationfrom land to waterbody using radiocesium distribution and soil to sediment ratio: A case of thesteep slope catchment area of Ogi reservoir, Kawauchi Village, Fukushima, Radiation Safety
Management, 19, 23-34 (2020). DOI 10.12950/rsm.190924.
3. M. A. Habib, T. Basuki, S. Miyashita, W. Bekelesi, S. Nakashima, K. Techato, R. Khan, A. B.K.
Majlis, K. Phoungthong, Assessment of natural radioactivity in coals and coal combustion
residues …… Environmental Monitoring and Assessment, 191: 27 (2019). DOI10.1007/s10661018-7160-y.
4. M. A. Habib, T. Basuki, S. Miyashita, W. Bekelesi, S. Nakashima, K. Phoungthong, R. Khan,M. B.
Rashid, A. R. M. T. Islam, K. Techato, Distribution of naturally occurring radionuclides in soil
around a coal-based power plant and their potential radiological risk assessment, Radiochimica
Acta (2018).DOI 10.1515/ract-2018-3044.

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