8. Neutron Radiography and Radiation Application

概要

CO8-1

Demonstration experiment of detecting the HEU sample using a low-cost inspection system

M. Komeda1, K. Tanabe2, Y. Toh1, Y. Kitamura3 and
T. Misawa3

tron time distribution were performed by a multi-channel
scaler (MCS) that was synchronized with the disc rotation signal from the servomotor.

Nuclear Science and Engineering Center, Japan Atomic
Energy Agency
2
National Research Institute of Police Science
3
Institute for Integrated Radiation and Nuclear Science,
Kyoto University
1

INTRODUCTION: A compact and low-cost
non-destructive inspection system to detect hidden nuclear material is required in the fields of nuclear security.
We developed a new nuclear material detection method,
called the active rotation method, using a neutron source
of Californium-252. In the method, a neutron source is
rotated at a speed of thousands of rpm by the rotation
machine nearby a measurement object. Meanwhile, it is
possible to detect nuclear materials by confirming the
deformation of the time-distribution spectrum obtained
by a neutron detector near the object. The rotation machine is compact and low-cost. In addition to the rotation
machine, we developed a water Cherenkov detector as a
low-cost neutron detector. In previous studies, we accomplished detections of natural uranium of approximately 8,000 g by using a low-cost non-destructive nuclear material detection system composed of a rotation
machine and a water Cherenkov neutron detector
(WCND) in KUCA[1]. The purpose of this year is to
detect smaller nuclear material, which is approximately 4
g of highly enriched uranium (HEU) using the developed
system.
EXPERIMENTS: The experimental setup is shown in
Fig.1. The dimensions of the neutron rotation machine
are approximately 60cm in width, depth, and height. The
rotation machine can rotate the disk (diameter 32cm),
where a neutron source is installed at its outer periphery,
at a rotation speed between 0 and 4000 rpm. A neutron
source of Californium-252 is set in the disk, the radioactivity was 2.2 MBq. It is noted that the 2.2 MBq is
smaller than the 3.7 MBq of the Japanese-approved devices with a certification label of Californium-252. In
this experiment, we used approximately 4 g of HEU. The
uranium sample was surrounded by polyethylene blocks.
The WCND basically consists of an aquarium
(30x25x30cm) and four PMTs (Photomultiplier tube).
The PMT (2 inches diameter) is the Hamamatsu
H11284-100. A transparent acrylic panel is attached to
the top of the aquarium, installing the PMTs there. Since
water filled up to the top surface, there was no air gap
between the PMT and water. Measurements of the neu-

RESULTS: Figure 2 shows an example of experimental
results of the HEU sample when the rotation speed is
4000 rpm. The measurement time for the experiment was
10 minutes. A comparison between the time-distribution
spectra at 4000 rpm and 300 rpm reveals that the integrated value after the center (around 6000 micro-seconds
at 4000 rpm) increased only for the HEU sample, but not
for a blank sample (sample without nuclear material).
Thus, we have successfully detected approximately 4 g
of HEU using low-cost non-destructive nuclear material
detection system.

Fig. 1. The rotation machine (left), the water Cherenkov
detector (right), and measurement object containing HEU
(middle).

Fig. 2. Neutron events distribution of the HEU sample. The
measurement time was 10 minutes with the rotation speed
of 4000 rpm.
REFERENCES:
[1] K. Tanabe et.al., J. nucl. sci. technol., (2022).
(doi)10.1080/00223131.2022.2143449.

R4CA01
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CO8-2

Establishment of a novel mutation breeding using Boron Neutron Capture Reaction (BNCR)

M. Kirihata, S. Segami1, Y. Hattori, T. Kinouchi2,
Y. Kinashi2
Research Center of BNCT, Osaka Prefecture University
1
Research Institute of Environment, Agriculture and
Fisheries, Osaka Prefecture

Institute for Integrated Radiation and Nuclear Science,
Kyoto University
2

INTRODUCTION: Boron Neutron Capture Reaction
(BNCR) is based on the nuclear reaction of 10B atom with
thermal/epithermal neutron already applied to cancer
treatment (BNCT) [1, 2]. As a new utilization method of
BNCR, this study aims to establish a novel mutation
breeding using BNCR.
The method attempts mutagenesis by immersing plant
seeds in a 10B-enriched boron compound, re-drying, and
then irradiating the seeds with thermal neutrons to induce
BNCR. A similar method has been tried with barley and
observed an effect in the M1 generation and a mutagenic
effect in the M2 generation [4, 5]. Its mutagenic effect depends on chemical and physical factors such as 10B concentration, thermal neutron intensity, and irradiation time.
In our previous experiments, they have tried immersing
seeds in 10B-enriched p-boronophenylalanine (BPA) [3]
and 10B-enriched boric acid (H310BO3) as 10B-enriched
boron compounds in rice. The germination rate of each
treated seed was investigated after BNCR, and the results
showed that there was no decrease in germination rate for
BPA-treated seeds in the 1-100 mM concentration range,
whereas H310BO3 treated seeds showed a concentration-dependent decrease in germination rate. It is assumed that these results are due to differences in the uptake of 10B into plant seeds by different boric acid compounds. Currently, the effects of mutagenesis are being
confirmed. This report selected disodium mercaptoundecahydrododecaborate (BSH), a boron cluster,
as a new boron compound to be examined.

and 2000 ppm BSH for 36 h. The solvent used was PBS
buffer. The samples were washed with water and re-dried.
The seeds in 6-mL tubes were irradiated with thermal
neutron for 90 minutes in the Kyoto University Research
Reactor (KUR). After the irradiation treatment, the seeds
were cultured in petri-dishes with continual moistening of
filter paper at 25℃ under a photoperiod of 16 h light and
8 h dark, and the germination rate was examined 14 and
21 days after sowing. As a control experiment, seeds that
were only treated with BSH soaking and not irradiated
with thermal neutrons were sown in the same method,
and germination rates were investigated.
RESULTS: BSH treatment did not decrease the germination rate with or without BNCR. This result is similar to
BPA treatment. In H310BO3 treatment, seeds immersed for
24 or 36 h in solutions of 50 mM or higher concentration
have been found to significantly decrease the germination
rate of seeds with BNCR, in our results. These results
indicate the selection of boron compounds to be used in
this mutation breeding in BNCR. To determine these differential effects on germination rate, the uptake and localization of 10B in seeds are currently being investigated
using molecular biological techniques. In addition, the
treated M1 and M2 generations are being grown sequentially in the field to investigate mutants.
REFERENCES:
[1] H. A. Soloway et al., Chem. Rev., 98 (1998)
1515-1562.
[2] B. Farhood, et al., Rep. Pract. Oncol. Radiother., 23
(2018) 462-473.
[3] H. R. Snyder, et al., J. Am. Chem. Soc., 80 (1958)
835-838.
[4] Y. Ukai and A. Yamashita, Institute of Radiation
Breeding Tech. News, 30 (1987).
[5] T. Morikawa, et al., KURRI Progress report 2012
(2013) 170.

EXPERIMENTS: The experimental material used Oryza sativa L. cv. Nipponbare. ...