CO10-1 Possibility of Suppression of Cs Elution from Incineration Fly Ash by Adding Soil

Faculty of Engineering, Kyoto University
1Research Reactor Institute, Kyoto University

INTRODUCTION: The procedure to the final disposal of the waste polluted with radioactive Cs in Fukushima
is far from well established. In carrying out a middle
storage of the polluted waste and its final disposal, it isnecessary that behaviors of radioactive Cs in the wastes
are clarified and a realistic method is suggested to prevent leakage of radioactive Cs to the environment in future to establish the safe disposal method of the waste.
This study examines the effectiveness of the method tomix the soil which had strong adsorption ability of the Cs
with incineration fly ash as elution suppression measures.
EXPERIMENTS: At first, behavior of stable Cs-133of the concentration of 500µg/kg and radioactive Cs-134of the concentration of 125,000Bq/kg (2.6ng/kg) is compared when they are added to heat treated forest soil as adecontamination waste. Here, heat treated forest soil
means that the soil is heated for 30min at 500 degree
Celsius by muffle kiln. Soil of experiment forest of Iwate
University is used, because it is thought to be similar toforest soil in Fukushima. Then, the elution rate to waterof Cs from the mixture of a simulated incineration fly ashand heated or unheated forest soil is examined by themethod of elution test of Soil Contamination Countermeasure Law considering the quantity of K as a competitive adsorption element contained in the mixture. Table 1
shows the components of the simulated fly ash. Stable
Cs-133 is used if there is no clear difference in the elusion rate from soil between Cs-133 and Cs-134.
Table 1. Components of simulated incineration fly ash.
fly ash A
fly ash B
componentratio (%)
component
ratio (%)
activated C
3.0 activated C
3.0
KCl
10.0 KCl
4.0
SiO2
86.8 NaCl
4.0
metals
0.2 CaCl2･2H2O
2.0
SiO2
29.0
Al2O3
29.0
CaCO3
29.0
RESULTS: Although the concentration of Cs-133 andCs-134 are 5 order of the magnitude different, there wasno clear difference between in the elution rate of Cs-133
and in that of Cs-134 from heated soil. The elution rate ofCs from heated forest soil was less than 1%. However,28033

the drop of the elution rate from incineration ash by adding heated or unheated forest soil was not so effective as
we expected. Fig.1 shows the elution rate of Cs from themixture of the simulated fly ash and heated or unheatedforest soil. It was necessary to mix the soil of the quantityof a little less than 10 times of fly ash to drop the elution
rate to around several percent. When the soil and fly ash
was mixed, the concentration of [K+] (meq/mL) in thesolution of the elution test would be approximately estimated by the contents of element K of the simulated fly
ash, if the content of K was much bigger than the cationexchange capacity (CEC) of the soil in each mixture. We
found that we could estimate the elution rate of Cs by theequation (1) based on Langmuir type competition adsorption theory when we mixed soil and fly ash.
(1)
elution rate (%) =100/(1+ 0.05/ [K+])When quantity of K in the mixture of soil and fly ash islarger enough than quantity of CEC, [K+] can be approximately estimated as total K minus CEC of the mixture solved in the solution. It was possible to estimate
each observed Cs elution rate with around 10% of errors
by the equation (1). Therefore, it means that it is necessary to suppress [K+] less than 0.5 x 10-3 (meq/mL), or
the contents of Cs in each mixture less than around 0.5 x
10-2 mmol/g to control each elution rate of Cs less than1%. In addition, it was expected that the behavior of Cs
in the mixture would be greatly change if the contents ofCs exceeded the contents of frayed edge site where Cs ispreferentially sorbed. Because the amount of frayed edgesite of the soil used in this study was around 0.0002(meq/g), behavior of Cs in the soil would not be different
if the amount of Cs added to the soil is less than 27mg/kg.
It was also found that when the amount of Cs was morethan the amount of frayed edge site, the elution rate could
be estimated based on the competition adsorption theoryof the Freundlich type, though the effect of the differenceof soil parameters was great.
120

Ash A, unheated soil
Ash A, heated soil
Ash B, unheated soil
Ash B, heated soil

100Cs elution rate (%)

M. Yoneda, Y. Shimada, M. Matsui, A. Taruoka, Y.
Yoshiyama, T. Kometani , D. Setoguchi, S. Fukutani1 andM. Ikegami1806040200020406080

100

mixture rate of soil (%)

Fig. 1. Elution rate of Cs from mixture of simulated incineration fly ash and soil.

CO10-2Ethnographic Study on Nuclear Reactor- Safety and Relief in Fukushima, post 3.11. -M. Takagaki, K. Uno and S. Masunaga1
Leuis Pasteur Center of Medical Research
1Research Reactor Institute, Kyoto University
At the end of March 2017, after the seventh year of theearthquake disaster, governmental order for evacuation
was mostly terminated except for Nagadoro where radiation levels are still high. The radiation level in the livingzone of Iitate village has decreased to less than 0.3µSv/hr and it is about 1 µSv/hr even when going to worship deep in the mountain of Yamazumi shrine that worships the local mountain gods (Figure 1). The form of life
style of villagers is varied, after the evacuation order forthem is terminated. Villagers trying to return home in
Iitate immediately will be less than 20%. Most of them
are elderly people with little risk of radiation damage,and it is difficult to regenerate the community. The only
clinic that has restarted at Iitate manages the outpatient
clinic only twice a week in the morning.

Figure 1. GPS-mapping of environmental radiation distribution on Google around the central Iitate. Radiationdose of almost all living areas are less than 0.3µSv/hr(3.16, 2017).
1. Nuclear bio-politics
Is there any justification of the scientific basis for thepolitical evacuation direction against the disaster area?
Unfortunately, it must be said that the scientific basis ofregulation was lacking. Safety standards extrapolated
from model experiments of radiation safety management
and regulation standards in the field are considerably
divergent. It can be said that it is rather a different concept. Experimental condition setting does not reflect thecurrent situation in the field. Sciences (eg, radiobiology)
were ineffective and impossible to regulate the field
based on their experimental results. Nonetheless, the importance of scientific advice for political administrationis recognized as an issue to be discussed more and more
after 3.11 disaster (1). How can scientific advices [scientifically] reflect on political administration? Despite thenecessity of politically neutral think tanks and scientificbrains of politicians, etc. have been advocated, why did
not they work in this 3.11 disaster? I believe that there
was already a problem in the planning and establishment
process of Japanese Basic Nuclear Energy Law (196thDecember 19th Act No. 186).
2. Engine called law to drive bio-politics
Since there is a legal system of nuclear energy policy
starting with the Basic Law of Nuclear Energy, bureaucrats can not "take a step" within the low, and will pro-28034

mote nuclear power politics endlessly along the law. It isdifficult to change the bureaucratic mind for safety regulation unless the law will be changed (2). Bureaucrats arerobots that run by law. Since nuclear power administration consists of inevitable incorporation of plutonium
cycle from the beginning, abandoning nuclear reactors at
the present time is a politically incompatible choice. In
creating safety regulations, science that fills the gap between the scientific safety and the relief of victims
should be established (for example, regulation anthropology). Many villagers can not return home safely evenif evacuation regulation is terminated. It is not a simple
matter of radiation dose in the field. It is a problem that
there are significant estrangement between environmental safety and victim's feeling for relief.
Case study in which occupational prompt resuming wasreliably connected to victim's relief: Mr. K was 54 years
old (at the time of the disaster), a public officer, has
worked with side jobs for Turkey bellflower, rice andhoney, but after the disaster early retired from officer andevacuated temporarily, but immediately after July 2011
Later, leaving his family at refuge and seeking new
farmland in the neighboring prefecture to start his life
work as a house farmer mainly for Turkey bellflower.
However, there was no administrative support in entrepreneurship in other prefectures, and in the situation that
there was no subsidy payment immediately after the disaster, they were forced to start their own business without any administrative supports.
「From the officers in Iitate village, I was treated as atraitor. But I got into this place with a strong mind that I
could not live any more without resume of my life work.
Initially I had difficulty with village ostracism, harassment etc. But I am now contributing to the rebuilding of
the village for my success in bussiness.」 Regional administration that does not support diaspora-like reconstruction in order to enclose villagers in the village, as aresult, it can not escape from the driving force of the national nuclear power administration. On the other hand, isthe unconscious resistance of the vulnerable people whoare not bound by administrative districts and bricolages
even farmlands might become a sustainable reconstruction power? (3). Many of the villagers were cultivation
pioneers from 2 to 3 generations ancestors (Iitate Son-Shi,1979), culture inherited from ancient times has become
one of the bricolagic driving force through the network
for their recovery. As seen in the Nanohana project (hybrid plant of radiation pollution and nature) in radiation
contaminated environments in Fukushima, the driving
force of reconstruction can be found even in the hybrid
structure with pollution, so in order to fit Latour's scientific theory into a low-level radioactive environment, weshould rethink the real nature and the progress of sciencein his theory.
References:(1) Takeo Arimoto, Yasushi Sato, Keiko Matsuo, Hiroyuki Yoshikawa.: Scientific Advice: Science, Technology, and Policy Making in the Twenty-First Century,
University of Tokyo Press, 2016.(in Japanese)(2) Alan Hunt, Gary Wickham.: Foucault and the Law:
Towards a Sociology of Law As Governance. Pluto Press,1994.
(3) Bruno Latour.: Nous n’avons jamais ere modernes.
La Decouverte, Paris, 1991.

CO10-3 Characteristics Measurement in High Gamma Ray dose Environments for a NeutronDetector and Amplifier Used in an Active Neutron Method
M. Komeda, M. Maeda, H. Tobita, T. Saito1, H. Tanaka1
Japan Atomic Energy Agency
1
Research Reactor Institute, Kyoto University
INTRODUCTION:
We have been working on the development of anon-destructive assay (NDA) of nuclear materials by using the fast neutron direct interrogation (FNDI) methodthat is one of active neutron methods. Now we are proceeding with studies for NDA methods in high gammaray dose environments, and then it is significant to investigate the influence of high gamma ray dose on a neutron
detector. An amplifier of the neutron detector for theFNDI system requires fast pulse shaping to prevent
counting loss. Furthermore, it is important to keep thebase line stable in order to reduce the pile-up due to thehigh count rate. We have produced amplifiers with thedouble delay-line shaping function to satisfy the requirements. The purpose of this experiment is to evaluate theperformance of the amplifiers under high dose-rate gamma ray environments. Note that the irradiation object inthis experiment is not the amplifier but a neutron detector.
EXPERIMENTS:
The experiment was carried out in the Co-60 gamma-ray irradiation facility. Figure 1 shows an amplifier,which is 18 cm in length, 4 cm in width and 3 cm indepth. The experimental setup is shown in Figure 2. We
utilized He-3 neutron detector (proportional counter) thatwas 1 m in length and its pressure was 4 atm. The amplifier was mounted in close proximity to the detector. Leadblocks were set in front of the amplifier in order to reduce
gamma rays. Since neutron signal from the detector wasnecessary, a neutron source (Cf-252) with polyethylene
moderator was attached on the detector. The gamma ray
dose-rate was varied from 1.3 Gy/h to 8.0 Gy/h bychanging the distance between the gamma ray source andneutron source. We measured neutron counts at gamma
ray irradiations.
RESULTS:
Table 1 shows relative neutron counts compared tocounts at 0 Gy/h. It was found that the ratio was reduced
by 25 % at 2.0 Gy/h and 50 % at 4.0 Gy/h though theratio at 1.3 Gy/h was almost constant. These results will
give us important information to develop a new measurement system in high gamma ray dose environments. In
the future, we will examine other neutron detectors foruse in such severe environments. It may enable us toachieve further improvements.

28086

Fig. 1 Amplifier for a neutron detector

Fig. 2 The experimental setup

Table 1 Relative neutron counts
Gamma raydose-rate (Gy/h)

1.3

2.0

4.0

8.0

Neutron counts

1.06

0.75

0.50

0.26