10. Health Physics and Waste Management

概要

CO10-1 Application of KURAMA-II to Radiation Monitoring of Soil Separation Facilities
in Fukushima Prefecture
A. Maekawa, H.Hada1, H. Inoue and M. Tanigaki2
Fukushima Prefectural Centre for Environmental Creation
1
Interim Storage Facility and Decontamination Management Division, Fukushima Prefectural Government
2
Institute for Integrated Radiation and Nuclear Science,
Kyoto University
INTRODUCTION: KURAMA (Kyoto University RAdiation MApping system)-II is a radiation measurement system characterized by its compactness, autonomous operation, and acquisition of pulse-height spectrum data (Fig. 1)
[1]. KURAMA-II measures ambient dose equivalent rate
(hereafter referred to as air dose rate) and GPS position
and automatically transmits them to a dedicated cloud
server. We used a backpack-style KURAMA-II (Fig. 2) for
the radiation monitoring of soil separation facilities in an
interim storage facility to assess whether the radioactive
material was scattered under demolition.

A CsI (Tl) scintillation detector (C12137-4034, Hamamatsu Photonics) was used for measurement. The air dose rate
and GPS position were measured every second. For 1st
measurement, the air dose rate was measured by walking
along the facility's boundary under demolition. After the
demolition, 2nd measurement was carried out in the whole
area of the facility. The measurement data were averaged
in a 15-meter mesh and visualized to the colored air dose
rate maps using GIS software (QGIS 3.20.3). Several
points of the boundaries of facilities were measured by a
NaI (Tl) scintillation survey meter.
RESULTS: The air dose rate maps are shown in Fig.3-6,
and the ranges of the air dose rate are summarized in Table
2. No apparent differences were found between 1st and 2nd measurements at both
facilities. KURAMA-II results were comparable to those of the survey meter. As
shown in Fig.5 and 6, no apparent contamination was found in the study area. In
conclusion, no clear effect of the demolition of the soil separation facilities on the
air dose rate was found in the present study.

Fig. 1. A typical example of pulse-height spectrum
obtained by KURAMA-II measurement.

Fig. 3. 1st measurement
at facility A.

Fig. 4. 1st measurement
at facility B.

Fig. 5. 2nd measurement
at facility A.

Fig. 6. 2nd measurement
at facility B.

GPS

Detector

Fig. 2. KURAMA-II in a backpack.
EXPERIMENTS: The air dose rates of two soil separation facilities (facility A and facility B) were measured on
foot with a KURAMA-II in a backpack. The date of the
measurement and the demolition period are shown in Table
1.
Table 1. The date of the measurement and the demolition
period.
Facility A
Facility B
Apr. 2022
Jun. 2022
Demolition
- Nov. 2022
- Oct. 2022
1st measurement
13 Jul. 2022
13 Jul. 2022
2nd measurement 16 Dec. 2022
16 Dec. 2022

Table 2. The air dose rates measured by KURAMA-II and
by survey meter (Sv/h). The range of KURAMA-II (1st)
was calculated from the mesh measured in both measurements.
Method
Facility A
Facility B
KURAMA-II
0.06-0.11
0.07-0.40
1st
Survey meter
0.08-0.11
0.11-0.28
KURAMA-II
0.07-0.11
0.09-0.35
2nd
Survey meter
0.08-0.12
0.10-0.33
REFERENCES:
[1] M. Tanigaki et al., Nucl. Instrum. Meth. Phys. Res., 781
(2015) 57-64.

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CO10-2 Effective Measures on Safety, Security, Hygiene and Disaster Prevention in Laboratories
T. Iimoto1, M.M. Hasan1, H. Koike1, Y. Cai1, T. Miyazaki1, K. Takamiya2
1

The University of Tokyo
Institute for Integrated Radiation and Nuclear Science,
Kyoto University
2

INTRODUCTION:
Important aspects of the study can be found in the following keywords, such as safety, security, hygiene and
disaster prevention. Nuclear research reactor is one of
representative facilities together with these keywords
under their operation. It is effective to investigate the
latest status on practical measures on these keywords in
various facilities including nuclear research reactors, to
compare each other among facilities, and to discuss more
optimized ones for our positive safety management.
Through this process, it is also essential to investigate the
latest international and/or national regulations and the
movement of revision of them. In addition, development
of human resource and public literacy on nuclear science
and technology is also within the scope of the research.
The total discussion contents and their fruits are directly
useful for all relating laboratories.
RESEARCH APPROACH:
General research approach is as follows.
- Measures of safety management during operation or
standstill status of the real facilities would be investigated. This information would be used for our research
discussion on the positive and more optimized safety
management.
- It would not be a single year research, but maybe two to
three years research for one theme.
- Information source of facilities would not be only KUR,
KUCA or the other facilities in Kyoto University, but
also the Kindai university research nuclear reactor or the
facility of National Institute of Fusion Science, etc. This
research is an active joint-research with these relating
facilities and positive researchers on safety management.
- One of the distinctive features of this research is to involve office staffs as cooperators as well as researchers
and technical staffs. In The University of Tokyo, most of
the members in Division for Environment, Health and
Safety are office staffs who knows real situation of
safety management in laboratories very well.
Concrete discussion target in FY of 2022 was determined
as the followings; “developing a set of educational videos
for safety managers and researchers in universities using
accelerators” and “analysis of effects on radiation education in secondary schools.

DEVELOPING EDUCATIONAL VIDEOS IN UNIV.
FOR USERS OF ACCEARATORS:
A refresher training videos "Accelerator Safety Application for Radiation Workers in The University of Tokyo”
were produced. With the cooperation of the managers and
experts of the off-campus facilities (e.g. J-PARC and
KEK), the contents were carefully examined and included features and safety points for each facility that should
be communicated to radiation workers in advance, not
only for radiation workers of the facilities at The University of Tokyo, but also for ones sent to the off-campus
facilities.
The educational items were subdivided into the following
six issues, which were presented as short videos of 5 to 8
minutes each, with a maximum overall duration of 45
minutes or less. These are (1) types and characteristics of
accelerators, (2) safe handling of accelerators, (3) examples of accidents and troubles related to accelerators, (4)
on-campus accelerator facility - MALT section, (5) domestic accelerator facilities - J -PARC, and (6) domestic
accelerator facilities -KEK. Each facility section of (4) to
(6) includes facility features, main research achievements,
safety considerations and a message from the administrator.
ANALYSIS OF RADIATION EDUCATION EFFECTS IN SECONDARY SCHOOL
A questionnaire survey of secondary schools and their
teachers in eight countries in the Asia-Pacific region, including Japan, was conducted from around the end of
2020 to the end of 2021. The survey asked about the
teachers' values on radiation, an overview of the actual
implementation of the lessons (e.g. the content of each
item), and the students' impressions, knowledge and interest in radiation.
We analyzed the results of questionnaires on the effectiveness of radiation education in secondary schools. The
degree to which students perceive radiation as ”Interesting” became stronger after the STEAM radiation lecture.
Radiation education with the WOW factor is effective. In
the analysis of changes in students’ impressions based on
teacher characteristics, teachers who perceive radiation
as ”Simple” or ”Easy to be understood” are more likely
to teach radiation basics attractively. On the other hand,
in the overall analysis, the degree to which students perceive radiation as ”Interesting” or ”Easy to understand”
decreased when taught by the teacher who perceive it as
“Good”. It is possible the students were influenced negatively by the teachers' strong impressions and messages.

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CO10-3 Study of Penetration/Leaching Behavior from Concrete Contaminated with Cs
-Analysis of changes in mortar structure accompanied by dry-wet cyclesK. Kondo1 and I. Sato1
1

Tokyo City University

INTRODUCTION: Cesium (Cs) penetration/leaching
experiments on concrete of reactor containment structural
materials are contributed to understanding of contamination mechanism by radioactive materials, which is one of
six important issues identified by the Nuclear Damage
Compensation and Decommissioning Facilitation Corporation (NDF). The contaminated concretes are exposed to
the environment changes, which means that Cs concentration behavior may changes.
EXPERIMENTS: Mortar specimens (without aggregates) were made with ordinary Portland cement
(W/C=0.37, S/C=2.1) in a cubic of 15mm×15mm×15mm.
They were embedded into acrylic resin, so that only one
surface remains for penetration/leaching of Cs. The Cs
penetration solution (15 ml) was CsOH solution adjusted
to 10-2M. Table 1 shows four dry and wet conditions
given to mortars. For example, a penetration experiment
using mortar given condition 1 was named P1 and a
leaching experiment was named L1, and P1-P4 and
L1-L4 were prepared. The mortars of P1-P4 were soaked
in CsOH solution for 15 days for penetration. Mortars of
L1-L4 were soaked in CsOH solution for 15 days for
penetration and then in water for 15 days for leaching.
After the experiments, the mortars were scraped with
sandpaper (particle size: #60) to powder. The powders
were analyzed by INAA to determine amounts of Cs remaining in them.

and leaching behavior, it is possible that the different
number of dry/wet cycles may complicate the diffusion
phenomenon by physically and chemically changing the
mortar structure. ...