VIII-Ⅱ-1. Project Research
Project 10

PR10Creation of Unique Neutron Irradiation Experiments Using B-2 Beam Hole of KUR

K. Takamiya
Research Reactor Institute, Kyoto University

Objective: New neutron irradiation apparatus had been
installed in B-2 beam hole of Kyoto University Research
Reactor (KUR) in 2012. Samples loaded on a carrier canbe transported from a station at an experimental room toan irradiation field in the B-2 beam hole by the apparatus.
The carrier can transport a sample of sizes up to 6 cm x 6
cm x 30 cm and weight up to 10 kg. And the carrier canbe connected with wires or tubes to monitors or instruments located at the experimental room. Various uniqueneutron irradiation experiments, such as an irradiation to
circulating liquid sample and online monitoring of neutron-irradiated materials, can be performed using the apparatus. In this project work, basic experiments as thefirst steps for applications of advanced neutron irradiation
experiments in various research fields has been carriedout.

We have six themes in the project research. One is for measurements of fundamental
data about irradiation fields, three are basic researches
for advanced irradiation experiments, and two are developments for advanced experiments. The respective
subjects of the research groups of this project are described as follows;
P10-1: Measurement of neutron flux at various irradiation positions in B-2 beam holeP10-2: Basic research for application to biological experiments
P10-3: Development of irradiation method for circulating liquid sample
P10-4: Basic research for application to neutron activation analysis (NAA)
P10-5: Basic research for application to fundamental
chemistry
P10-6: Development of irradiation method for biological samples
In this year period, experiments of P10-6 were not carried out because of a trouble of a sample carrier.
Research Subjects:

Results: In the measurement of irradiation characteristics in B-2 beam hole, the flux and uniformity of irradiated neutrons and the Cd ratio were measured by activation method. The flux measurements were performed at
positions of 0 to 300 cm from the reactor-side edge of theB-2 beam hole at intervals of 50 cm. The wide range ofneutron flux that is from 108 to 1012 n/cm2/s was observed at 1 MW operation. The uniformity of neutron
flux was measured by activation method using PET films
at positions of 0 to 300 cm at intervals of 100 cm. The
neutron flux was found to be uniform by IP images ofirradiated PET films. The Cd ratios were measured at thepositions of 100 to 120 cm with/without a polyethylene(PE) shield. The Cd ratio without the PE shield decreases
as the range from the reactor-side edge. On the other side,
The Cd ratio with the shield increases and seems to besaturated at the position of 15 cm from the shield surface.
This means irradiating neutron spectrum is controllable
by using shield materials for the purpose of each experiment.
In the basic researches for biological, NAA, chemical
studies, various irradiation tests has been carried out. In
the irradiation tests for biological samples, the gamma-ray dose rate has been measured by thermoluminescence detectors (TLDs) at positions of 100 to 300 cm atintervals of 50 cm because not only neutrons but also
gamma rays affect biological samples strongly. And thesuitable irradiation time for alpha autoradiography technique to obtain intracellular boron distributions with highposition resolution is estimated by measured neutron
fluxes at B-2 beam hole and irradiation results by TC-Pn.
For application to NAA experiments using B-2 beamhole, irradiation tests for large volume samples (1.0 g, 10
g and 40 g) of quartz sand in 20 mL polypropylene (PP)bottles have been carried out. After the irradiation, there
found no irradiation damages to PP bottles, and radioactivities of the samples were analyzed by γ spectrometry.
On the basis of obtained data, experiments on environment samples and longtime irradiation are planned.
Irradiation tests for liquid samples have been performed as the first step of chemical experiments using
activated liquid samples. Irradiation damages to polyethylene bottles were checked and also irradiation test to
water in the bottle was performed. In the water sample
irradiation, the sample of 15 mL pure water in a PE bottle was irradiated for 2 min at the position of 150 cm.
After the irradiation, radioactivity of the sample was analyzed by γ spectrometry.
For the development of irradiation method for circulating liquid samples, radiation tolerance of a PFA tube
that is a main material of the liquid circulation system
has been checked. PFA tubes were irradiated by neutron
at the position of 0 cm for 10 min or at 200 cm for 60
min. And the tubes were also irradiated by Pn-2 irradiation hole for 1 or 10 min. After the irradiations, tensile
test was performed and it was found that the dose of
7.2×1014 n/cm2 does not cause serious problems on theperformance of the PFA tube. Therefore, the safety for
2-hour irradiation at the position of 0 cm in B-2 beamhole is confirmed.

採択課題番号 24P10 Ｂ２照射孔を利用したユニークな中性子照射実験の創出（京大・原子炉）高宮幸一

プロジェクトCharacteristics of Neutron Irradiation Field at B-2 Beam Hole in KUR

INTRODUCTION: Neutron irradiation experiments,
such as neutron activation analysis and isotope production, have been performed using various irradiation apparatuses at research reactors. One of the most general
neutron irradiation apparatus is a pneumatic transportsystem, which transports small capsules enclosing samples from a laboratory room to an irradiation hole near areactor core. However, sizes and weights of samples are
restricted by the transporting capacity of capsules. And
furthermore, an irradiation of liquid samples is not permitted because of reactor safety problem in almost all
research reactors. A new neutron irradiation apparatus has
been developed at Kyoto University Reactor (KUR, 5
MW thermal power) to overcome such limitations. The
apparatus transport samples loaded on a carrier from anexperimental room adjacent to the reactor to irradiation
fields in a horizontal beam hole (B-2) of KUR. Positionsof irradiation field can be changed that realizes various
neutron irradiation experiments. In this work, the neutron
flux has been measured at various irradiation positions of
the B-2 beam hole using the irradiation apparatus. And
neutron flux measurements using a polyethylene shield
have been tried to change irradiating neutron spectra for
irradiation experiments by various neutron spectra.

The neutron flux and its Cd ratio
were measured by activation method using gold wires.
The flux measurements were performed at the positions of 0 to 300 cm from the reactor -side edge of theB-2 beam hole at intervals of 50 cm. The Cd ratios
were measured at the positions of 100 to 120 cm
with/without a polyethylene shield (5 cm × 5 cm × 20cm). The uniformity of neutron flux was also measured by activation method using PET films [1] at thepositions of 0 to 300 cm at intervals of 100 cm.

1013
-1

Research Reactor Institute, Kyoto University
1
Graduate School of Engineering, Kyoto University

tion by IP images of irradiated PET films. The results of
Cd ratio (Au) measurement are shown in Fig. 2. Openand closed symbols show Cd ratios (Au) with a polyethylene shield and without it, respectively, at the positionof 100 to 120 cm. The Cd ratio without the PE shielddecreases as the range from the reactor-side edge. On theother side, The Cd ratio of gold shielded by PE increases
and seems to be saturated at the position of 15 cm fromthe PE surface. This means irradiating neutron spectrum
becomes softer by PE shield and is controllable in theirradiation apparatus using shield materials.

-2

K. Takamiya, Y. Yoshida1, T. Sano, H. Yoshino, Y. Iinuma,
R. Okumura and S. Shibata

Neutron flux / n・cm ・s

PR10-1

1012
1011
1010
109
108
107

100

200

300

Range from reactor-side edge / cm
Fig. 1 Neutron flux variation at the B-2 beam hole.

30

Cd ratio (Au)

EXPERIMENTS:

RESULTS: The results of the flux measurements depending on the range from the reactor-side edge at theB-2 beam hole are shown in Fig. 1. The wide range ofneutron flux that is from 108 to 1012 n/cm2/s was observed, which realizes various kinds of neutron irradiation experiments. The neutron flux decrease as the range
from the edge increases. The decreasing trend of neutron
flux changes around the range at 120 cm because thesectional shape of the beam hole changes around here.
The neutron flux was found to be uniform at every posi-

0

20

10

0

0
50
100 150 200
Range from PE surface / mm

250

Fig. 2 Cd ratio of gold with/ without the PE shielddepending on the range from the PE surface
at the position of 100 cm in the B-2 beam hole.
REFERENCES:[1] K. Takamiya, et al, Proc. Radiochim. Act. 1 (2011)63-66.

採択課題番号 24P10-1
Ｂ２照射孔における照射特性（京大・原子炉）高宮幸一、佐野忠史、吉野泰史、飯沼勇人、奥村良、柴田誠一（京大院・工）吉田悠矢

プロジェクトPR10-2

Study on the Improvement of Micro-Imaging for Boron Compounds I

H. Tanaka, K. Takamiya, Y. Sakurai, T. Sano, T. Fujii,
S. Fukutani, K. Ono and Y. Kawabata
Research Reactor Institute, Kyoto University

INTRODUCTION: It is important to develop newboron compounds for Boron Neutron Capture Therapy(BNCT). The accumulation ratio of the tumor to thenormal tissue of the boron compound which can be used
now is about 8 at the maximum. For an expansion of
BNCT adaptation, a boron compound with tens times
accumulation ratio is desired. However, the biologicaleffectiveness of a boron compound cannot be determined
only by an accumulation ratio. Because the boron concentration measured by ICP or prompt gamma ray analysis is the average value of the group of cells with different uptake of boron compound. If cells with same boron
concentration are irradiated by same neutron fluence, thebiological response changes greatly with the kind of boron compounds. In order to confirm the effect of boron
compound, tumor-bearing mouse administrated with boron compound and irradiated with neutrons should bebred for a long time. Then, the prediction of the characteristic of boron compound is performed by comparing
with the boron micro-distribution in a cell. Alpha autoradiography is used as a method of measuring boron micro-distribution in a cell [1,2]. In this research, the highposition resolution and simple measurement technique of
intracellular boron distribution will be developed. Furthermore, evaluation of irradiation time using B-2 irradiation hole is curried out for alpha autoradiography.
EXPERIMENTS: In order to estimate the relationshipbetween the boron concentration and the number of
etched pits created on CR-39 track detector or neutron
fluence. The sample administrated with boron compoundof 2.5, 12.5, 25 ppm was installed on CR-39. The sample
was irradiated by Tc pneumatic tube with thermal neutron
flux of 8x1010 (n/cm2/s) for 1 minute at KUR. After irradiation, CR-39 was etched by 6N NaOH. The etched
CR-39 was observed by optical microscope.
The tissue sample administrated with boron compoundof 25 ppm was also irradiated with thermal neutron. After
irradiation, the tissue sample stained by Hoechst was observed by fluorescence microscope in order to identify
cell nucleus and etched by 6 N NaOH. The etched CR-39
was also observed by optical microscope.
RESULTS: Fig. 1 shows the relationship between thenumber of etched pits in the area of 1.1x104 (m2) andthe boron concentration. The good linearity was obtainedin this experiment. The neutron fluence of 4.2x1012 (cm2)is enough to observe clearly the etched pits image. Fig. 2.

shows the superimposed cell nuclei image strained by
Hoechst and etched pits image. Irradiation time for tissue
sample with boron concentration of 25 ppm using B-2
irradiation hole at 100cm and 50 cm is estimated to 1200
and 95 sec, respectively for alpha autoradiography.

Fig.1. Relationship between the number of etched pits
and the boron concentration.

Fig.2. The superimposed image of etched pits on
CR-39 and cell nucleus strained by Hoechst. Arrows
and the part of enclosed white solid line indicatesetched pits and cell nuclei, respectively,
REFERENCES:[1] S. Altieri, S. Bortolussi, P. Bruschi et. al., Nuclear
Technology, Applied Radiation and Isotopes, 66(2008),
1850– 1855
[2] K. Ogura, A. Yamazaki, H. Yanagie et.al., Radiation
Measurements, 34(2001), 555–558

採択課題番号 24P10-2 ホウ素化合物のマイクロイメージングの高度化に関する研究 プロジェクト（京大・原子炉）田中浩基、高宮幸一、櫻井良憲、藤井俊行、福谷哲、小野公二、川端祐司

PR10-3

On-Line Production of Short Half-Life Nuclides Such as 142Prm Using KUR

H. Kikunaga, T. Ohtsuki1 and K. Takamiya1

mental conditions are summarized in Table 1.

Research Center for Electron Photon Science, Tohoku
University
1
Research Reactor Institute, Kyoto University

RESULTS: The tensile strength (TS) σ [MPa] andtensile elongation (TE) ε [%] are given by the following
equations:
𝐿𝑓
𝐹
σ=
, 𝜀=
𝐴
𝐿0
, where F is the maximum load [N], A is the
cross-section area of the material [mm2], 𝐿𝑓 is the final
length of the specimen, and 𝐿0 is the initial length of thespecimen. The TS and TE obtained are also listed in Table 1. Initially, the TS and TE become larger as theamount of dose increases. On the other hand, TS and TE
at the dose of 7.2×1014 n/cm2 is less than those of the noirradiation specimens, which is due to neutron damage on
PFA samples. However, taking TS and TE values into
consideration, it will be thought that even the dose of
7.2×1014 n/cm2 does not cause serious problems on theperformance of the PFA tube. Therefore, we conclude
that the irradiation for 2 h at the most remote part of B-2
is available. At present the prototype of the on-line irradiation apparatus for solution samples is under construction.

INTRODUCTION: B-2 beam hole makes it possible
to insert an experimental apparatus up to 1000 cm3 into
the Kyoto University Research Reactor (KUR) [1]. In
order to prepare radioactive sources of short half-life nuclides such as 142Prm (T1/2 = 14.6 min [2]) in various solution, we plan to develop an on-line irradiation apparatus
for solution samples at that place and to irradiate withneutrons while flowing a sample solution. There are few
studies about on-line irradiation of a solution using KUR,
so that, at first, we have studied radiation tolerance of the
PFA tube which is a main material of the irradiation apparatus. In this work, the PFA tubes were irradiated byneutron with various flux and then subjected to tensile
test to measure neutron damage.
EXPERIMENTS: Tensile specimens based on JIS K
6251 No. 8 size were prepared by stamping out from a
PFA tube with an outer diameter of 10 mm and a wall
thickness of 1 mm. The specimens were individually
sealed with a polyethylene film and irradiated with 1 MW
power using a supporting movable base emplaced at B-2
beam hole or Pn-2. The irradiation using B-2 beam hole
was carried out at the most remote part of B-2 for 10 min
with the fast neutron flux of 8.6×1010 n/cm2/s or 200 m
this side from the site for 60 min with 8.0×107 n/cm2/s. In
the Pn-2 irradiation, the specimens were inserted intopolyethylene capsules and irradiated for 1 min or 10 min
with 1.2×1012 n/cm2/s.
After the irradiation, tensile test was performed on these
specimens with a crosshead speed of 5 mm/min. Experi-

ACKNOWLEDGMENT: The authors would like tothanks K. Miyata, technical staff of KURRI, for thehelpful support on the tensile test.
REFERENCES:[1] K. Takamiya et al., in this KURRI Progress report.
[2] R. B. Firestone, in Table of Isotopes, 8th ed.,edited by
V. S. Shirley (Wiley, New York,1996).

Table. 1. Experimental condition and results of the tensile test.

採択課題番号 24P10-3 原子炉を用いた Pr-142 等の短半減期核種のオンライン製造（東北大・電子光セ）菊永英寿（京大・原子炉）大槻勤、高宮幸一

プロジェクトPR10-4

Neutron Irradiation of Large Volume Samples by Using the B2 Irradiation System

S. Fukutani, T. Fujii, R. Okumura and K. Takamiya
Research Reactor Institute, Kyoto University
INTRODUCTION: On analysis of environmental samples, representation of the sample is important and often
discussed. Instrumental Neutron Activation Analysis(INAA) is useful and superior method for elemental
analysis of environmental samples. But about 100mg
sampling for traditional pneumatic neutron activation
analysis, to keep the representation and homogeneity ofsamples is painful. The irradiation system for large volume samples may enable us to reduce the troublesometask of preparing analysis samples, and the system may
improve the representation of samples. The purpose ofthis study is to develop a system of neutron irradiation forlarge volume samples by using the new B2 irradiation
apparatus [1]. At first year of this project, we irradiatedquartz sand samples which were supposed to be stable
and little activation, and checked safety of the system andthe method.
EXPERIMENTS: The sample was irradiated for 2 min
by using the B2 facility of KURRI at a position of 150
cm from the core of the reactor. Experiments were conducted on 1MW operation, and the thermal neutron flux
at the 150 cm position is 9.4  108 n sec-1 cm-2. 1.0g, 10g
and 40g of quartz sand were taken in 20mL vol. polypropylene bottles(Fig.1) and were was irradiated. Afterthe irradiation, radioactivity of the sample was analyzedby  spectrometry.

empty space, and air in the empty space was irradiated at
the same time. It follows that Ar-41(1294 keV, 1.8h)
which is activated Ar-40, one of air components (0.934
vol.%), is detected. The same kind of quartz sand sample
was also irradiated by the orthodox pneumatic method(Pn-2, 1MW, 5.5  1012 n sec-1 cm-2, 30min, 138mg) andGamma spectrum after about 20 minutes cooling time isshown in Fig 3. A major component element ofquartz sand is silicon (Si) and the  ray peak of
Si-31(1266keV, 2.6h) which was activated of Si-30 (natural abundance ratio3.1%, 0.108b) was found clearly in
Fig. 3, but the  ray peak at 1266keV was trace level in
Fig.2. These are due to the difference of neutron flux andirradiation time, and possibility to eliminate interferenceof major matrix components is indicated. Experiments onenvironment samples and longtime irradiation areplanned.

Si-31 Ar-41
Mn-56

Na-24
Cl-38

Fig. 2. Gamma spectrum after about 90 minutes
cooling time of the 10g of quartz sand sample (B2)

Si-31

1.0g

10g

40g

Fig.1 1.0g, 10g and 40g of quartz sand samples
RESULTS: After the irradiation, samples and propylene bottles were sound, and no damage was found.
Gamma spectrum after about 90 minutes cooling time of
the 10g of quartz sand sample with the propylene bottle
is shown in Fig. 2. The irradiated bottle with sample had

Fig. 3. Gamma spectrum after about 20 minutes coolingtime of the 138mg of quartz sand sample (pn-2)
REFERENCES:[1] K. Takamiya et al., Proc. 47th KURRI Scientific
Meeting (2013) 124-126.

採択課題番号 24P10-4 環境サンプル中の微量元素分析における高信頼手法の開発（京大・原子炉）福谷 哲、藤井俊行、高宮幸一、奥村 良

プロジェクトPR10-5

Neutron Irradiation of Solutions by Using the B2 Irradiation System

T. Fujii, S. Fukutani, R. Okumura and K. Takamiya
Research Reactor Institute, Kyoto University
INTRODUCTION: Quantitative analysis of elements
dissolved in environmental water is important and quick
nondestructive analytical (NDA) method is useful for the
purpose. Neutron activation analysis is superior to analyze trace amount of elements, but there is no facility inJapan, in which the irradiation apparatus for liquid samples is installed. Generally, trace amounts of elements inliquid samples are recovered by using ion exchange resins or by precipitation methods. Collected samples areonce dried up. For nonvolatile elements, liquid samples
may be directly dried up. The dried samples were thenirradiated for NDA. Every method needs pretreatment ofliquid samples. The irradiation apparatus for liquid samples may enable us to reduce the pretreatment processes.
The purpose of the present study is to develop a systemof neutron irradiation for liquid samples by using the B2
irradiation apparatus [1]. We firstly checked irradiation
damage of polyethylene bottles and then tested neutron
irradiations of water in the bottle.

was about 20 mL and the space was filled with air. A 
ray of 1294 keV was found in the spectrum (Fig. 2a).
This is attributable to the activation of Ar in the air, thatis, 40Ar(n, )41Ar. The air inside the bottle was removed
and analyzed again. As shown in Fig. 2b, no gamma rays
were found. A  ray of 1642 keV found is due to 38Cl. A
trace amount of Cl2 in the air may have been activated.
The bottles were settled in a conveyor of the B2 system
by using Scotch tape. A trace contamination of Al might
have been introduced from the tape. Another possibility is
an impurity of the polyethylene bottle itself. Since thehalf-life of 28Al is short (2.2 min), the  ray of 1778 keV
was quickly disappeared during the analysis (Fig. 2b).

EXPERIMENTS: The sample was irradiated for 2 min
by using the B2 facility (Fig. 1) at a position of 150 cm
from the core of Kyoto University Research Reactor. The
thermal neutron flux at the 150 cm position is 9.4  108 n
sec-1 cm-2. 15 mL of pure water was taken in a polyethylene bottle and this was irradiated. Au foils were irradiated together as a neutron flux monitor. After the irradiation, radioactivity of the sample was analyzed by  spectrometry.
Fig. 2. Gamma spectra of irradiated polyethylene bottle.
a) With air inside the bottle. b) Irradiated air was removed from the bottle.
15 mL of pure water was taken in the polyethylene bottle
and this was irradiated. A few products of water were
tested. Besides the  rays shown in Fig. 2, two additional
 rays were found at 617 keV and 1461 keV. These wereassigned as  rays emitted from 80Br and 40K, respectively.
Intensity of these  rays was as small as that of 38Cl
shown in Fig. 2a.
Fig. 1. B2 irradiation system [1].
RESULTS: Gamma spectra of the polyethylene bottle
irradiated are shown in Fig. 2. The volume of the bottle

REFERENCES:[1] K. Takamiya et al., Proc. 47th KURRI Scientific
Meeting (2013) 124-126.

採択課題番号 24P10-5
Ｂ２照射孔における溶液試料の中性子照射（京大・原子炉）藤井俊行、福谷 哲、高宮幸一、奥村 良

プロジェクト