PR8

Development on Neutron Imaging Application

Y. Saitoframe rate neutron radiography to measure the film
thickness distribution.
ARS-2 applied neutron radiography to heat transfer
study on an adsorption refrigerator. In this ARS, visualization of adsorption amount distributions of ethanol in an
activated carbon powder bed, using Umbra method inneutron radiography.
ARS-3 visualized the flow in a tubular flow reactor for
supercritical hydrothermal synthesis of nanoparticle using neutron radiography. Measured mixing behaviors in
the tubular flow reactor were compared with the size
distributions of the synthesized nanoparticles.

Research Reactor Institute, Kyoto University
1. Objectives and Allotted Research Subjects
Neutron imaging provides valuable information whichcannot be obtained from an optical or X-ray imaging. The
purpose of this project is to develop the imaging method
itself and also the experimental environment for expanding the application area of the neutron imaging. The allotted research subjects are as follows:
ARS-1 Measurements of Multiphase Dynamics by Neutron Radiography (Y. Saito et al.)ARS-2 Quantitative Measurement of Adsorbed Ethanol
Amount in Activated Carbon Adsorber for Adsorption Heat Pump (N. Takenaka et al.)
ARS-3 Neutron Radiography on Tubular Flow Reactor
for Supercritical Hydrothermal Synthesis of
Nanoparticles (T. Tsukada et al.)
ARS-4 Characteristics of the Void Fraction under Transient Condition (H. Umekawa et al.)
ARS-5 Neutron imaging and optics development using
simulation of VCAD Systems (Y. Yamagata etal.)
ARS-6 Water and Salt Distribution in a Rice Hull Medium under Sodium Chloride Solution Culture(U. Matsushima et al.)
ARS-7 Measurement of Water Content in Hardened
Cement Paste by Neutron Imaging (T. Numao et
al.)
ARS-8 Hydrazine Thickness Measurement by NeutronRadiography at a Catalyst Bed during Operation(H. Kagawa et al.)
ARS-9 Development of Neutron Imaging Devices (H.
Iikura et al.)
ARS-10 Evaluation of the Moisture Movement in
High-Performance Concrete Subjected to Heating (M. Kanematsu et al.)
ARS-11 Effect of gravity on coolant distribution in
FGHP heat spreader (K. Mizuta et al.)
ARS-12 Study on Visualization of Organic Materials
between Metals for Advance of Industrial Products (A. Uritani et al.)
ARS-12 Study on Visualization of Organic Materials
between Metals for Advance of Industrial Products (A. Uritani et al.)
ARS-13 Visualization of Flow inside Fine Scale of Heat
Pipe (Y. Tsuji et al.)

ARS-4 was not performed this year.
ARS-5 was trying to develop a visualization techniquefor molding process by using neutron radiography andalso a neutron focusing mirror. A 100mm rotational ellipsoid mirror was fabricated and its focusing performance was investigated at the CN-3 port
ARS-6 was not performed this year.
ARS-7 was not performed this year.
ARS-8 was not performed this year.
ARS-9 was not performed this year.
ARS-10 evaluated the water distribution in the hardened cement paste (HPC) using neutron radiography. In
this study, experiments were carried out to investigate
two-dimensional moisture movement in HPC.
ARS-11 applied neutron radiography to observe coolant distributions in a flat heat spreader (FGHP). The effect of gravity on coolant distribution in the FGHP wasinvestigated by varying the heat load to the FGHP. At
present experimental conditions, at least 0.1 mm thickliquid layer in the wick area exists in the middle plates of
the FGHP.
ARS-12 applied neutron radiography to observe organic materials between metals for advance of industrial
products. Experiments were conducted at the E-2 port
and the test samples were bearing with and without
grease. From the CT reconstruction of the neutron images,
the grease distributions could be clearly observed.
ARS-13 applied neutron radiography to observe working fluid distributions in a house-made heat pipe, to understand the heat transfer process on a solid surface. Experiments were conducted at the E-2 port, and the heatpipe was visualized by changing he heat load from 6W to
30W. Cross sectional distributions of the working fluid
could be measured by the neutron radiography.

2. Main results and the contents of this report
In ARS-1, simultaneous measurements of water film
distribution in an air-water two-phase flow were performed by using a Liquid Film Sensor (LFS) and a high

採択課題番号 26P8
（京大・原子炉）齊藤泰司

中性子イメージングの高度化と応用

35

プロジェクトPR8-1

Dynamic Observation of Two-Phase Flow using Neutron Radiography

Y. Saito and D. Ito
Research Reactor Institute, Kyoto University
INTRODUCTION: Neutron radiography (NRG) is a
powerful tool for fluid flow visualization as well as
two-phase flow research. Gas-liquid two-phase flows in a
metallic pipe have been visualized clearly by using NRG.
However, it would be still difficult to obtain dynamic
information on such flows by NRG, because of insufficient neutron flux from neutron sources and poor efficiency of imaging devices. In this work, our imaging
system was improved and a denoising method for acquired image sequence was developed for high frame rate
NRG. Then, they were applied to air-water two-phaseflow measurements in a narrow rectangular channel. In
addition, a simultaneous measurement with an electricalconductance method was performed to investigate thedetailed structure of the two-phase flow.

Fig. 1. High frame-rate neutron radiography systema

EXPERIMENTS: Experiments were performed at theB-4 supermirror neutron guide facility [1] of the Research Reactor Institute, Kyoto University. The neutron
flux of the B-4 port is 5×107 n/cm2s and the beam widthand height at the beam exit are 10 mm and 75 mm, respectively. An imaging system for high frame rate NRG
consists of a neutron converter, a dark box with a single
mirror, a megapixel lens, an image intensifier and a highspeed camera, as shown in Fig.1. NRG images acquiredby this system were used to estimate the void fraction in
the channel gap. Since the measured data include severe
signal noises due to the statistical error in counting neutrons, a spatio-temporal filter was applied to enhance thequality of the void fraction distributions [2].
The test section has a rectangular cross section with 12
mm width and 2 mm gap. The vertical channel wasplaced at 1 m away from the neutron beam exit. The test
fluids are air and tap water at room temperature. A liquidfilm sensor (LFS) [3] based on an electrical conductancemeasurement was applied to visualize the water film
flowing in the narrow channel, which was installed on
one side of the channel walls. LFS has 7×32 measurement points and the distance between the points was 1.5
mm. The temporal resolutions of both measurements
were 200 Hz for NRG and 10,000 Hz for LFS.

b

c

d

Fig. 2. Measured and filtered results of void fraction distribution

Thickness [m]

2000

1500

bubble thickness (NRG)
film thickness (LFS)
film thickness (estimated)

1000

500

0

3

6

9

12

Distance [mm]Fig. 3. Bubble and liquid film thickness profiles
The typical results obtained by a simultaneous measurement with NRG and LFS were shown in Fig.3. The horizontal profiles of the bubble and film thicknesses are
represented. It is seen that the bubble occupies most of
the gap in the channel. Thin film on the LFS could bemeasured by LFS. The film thickness on the opposing
wall, which was estimated from the measured data of
NRG and LFS, is also plotted in Fig. 3. This thickness
profile agreed well with LFS result. Thus, the possibilityof liquid film measurement on another wall was shownby the hybrid measurement with NRG and LFS.

RESULTS: The typical void fraction distributions
measured by NRG are shown in Fig.2 (a) and (b). Highvoid fraction values indicate where the bubble exists, andthe size of bubbles could be roughly estimated from the
distribution. However, several signal noises were found
not only in the liquid phase region but also in the gas
phase. Thus, the 3-D non-local mean filter was applied tothe original images. The distributions filtered from Fig.2(a) and (b) are shown in (c) and (d), respectively. The
remarkable noises were reduced by the filtering process.

REFERENCES:[1] Y. Saito, et al., Nucl. Instr. Meth. Phys. Res., A, 651(2011) 36-41.
[2] Y. Saito and D. Ito, Proc. WCNR-10, (2014).
[3] D. Ito, et al., Exp. Fluids., 51-3 (2011) 821-833.

採択課題番号 26P8-1 中性子ﾗｼﾞｵｸﾞﾗﾌｨを用いた混相流のﾀﾞｲﾅﾐｯｸｽ計測に関する研究（京大・原子炉）齊藤泰司、伊藤大介
36

プロジェクトPR8-2

Quantitative Measurement of Adsorbed Ethanol Amountin Activated Carbon Adsorber for Adsorption Heat Pump

H. Asano, K. Murata, N. Takenaka, H. Murakawa, K.
Sugimoto, Y. Saito1, D. Ito1, Y. Kawabata1

relationship could be obtained for the adsorbed ethanolby the umbra method as plotted with the symbol of ●.
The measured values by neutron radiography wascompared with those reported by El-sharkawy et al. [2] inFigure 7. They proposed the Dubinin–Astakhov equation
for adsorbed ethanol amount on the same activatedcarbon based on the experimental results. It was
confirmed that the adsorbed refrigerant amount could bemeasured quantitatively by the neutron radiography.

Department of Mechanical Engineering, Kobe University
Research Reactor Institute, Kyoto University

1

INTRODUCTION: Adsorption refrigerator is one of
the efficient tools to recover waste heat at a lowtemperature. A design of the adsorber, in which
refrigerant is adsorbed in adsorbent particle bed, is a key
part for the improvement in the performance. To design
the configuration of adsorber, it is required to clarify theadsorbed refrigerant distribution in the adsorbent particle
bed during adsorption/desorption process. Neutron
radiography was applied to visualize the adsorption
amount distribution of ethanol in an activated carbon
particle bed. The umbra method was applied tocompensate the neutron scattering effect for quantitative
measurement.

3 mm x 3 mm checked grid
Measured area
50×50 pixel
Neutronabsorber
Observed area

Fig. 1 Neutron absorber grid for umbra method.
With the cmpensation by the umbra method
Liquid ethanol
Adsorbed ethanol
Without the compensation
Adsorbed ethanol
2.5
2.0

r m,r r [-]EXPERIMENTS: Activated carbon and ethanol wasused as the adsorbent and refrigerant, respectively. The
activated carbon MAXSORB® III produced by Kansai
Coke and Chemical co., ltd. was used as the adsorbent. At
first, the mass attenuation coefficient of liquid ethanol
was measured using an ethanol step. Then, quantifiability
in the measurement of adsorbed ethanol amount in
activated carbon particle bed was evaluated by themeasurement of an adsorbent step in dry and adsorption
equilibrium condition. The adsorbent temperature was
21.5 °C and the pressure was 4.09 kPa. The umbra
method using neutron absorber was applied to thequantitative measurement. A checked neutron absorber
grid shown in Fig.1 was newly made for two-dimensional
measurements. The offset value for an observed area canbe measured by interpolating the brightness at theposition covered by the neutron absorber surrounding theobserved area. The width of the grid was 3 mm.

1.5
1.0
0.5
0

0
5
10
15
20
25
Thickness of the adsorbent/ethanol step [mm]rr [g/cm2]

Adsorption amount in equibribrium
by El-sharkawy et al. (2008)

Fig. 2 Attenuation of neutron beam for various thickness of the adsorbent or ethanol step.

RESULTS: The measured results of the liquid methanol
step are plotted with the symbol of ▲ in Fig. 2. The
vertical axis shows the product of density, , massattenuation coefficient, m, and thickness along theneutron beam, . The subscript r means ethanol as therefrigerant. A liner relationship between ethanol
thicknesses and rm,rr could be successfully obtained.
The mass attenuation coefficient calculated from thegradient was 3.86 cm2/g. For the measured results ofadsorbed ethanol without the compensation plotted withthe symbol of ○, the values seemed to become saturated
due to the effect of neutron scattering and stray light inthe camera system. It could be seen that the linear

0.6
0.4
0.2
0

0
0.2
0.4
0.6
Adsorption amount measured
by neutron radiographyrr [g/cm2]

Fig. 3 Comparison of adsorption amount in equilibriumwith the calculation by El-sharkawy et al.[2].
REFERENCES:[1] N. Takenaka, et al., Nondestructive Testing and Evaluation, 16-693 (2001), 345-354.
[2] I.I. El-Sharkawy, et al., Int. J. of Refrigeration, 31-8
(2008), 1407-1413.

採択課題番号26 P8-2
中性子ラジオグラフィによる機器内流動の可視化計測
プロジェクト
（神戸大・工）竹中信幸、浅野等、村川英樹、杉本勝美（京大・原子炉）齊藤泰司、伊藤大介、
川端祐司、（神戸大・工）村田健太、中村俊裕、北村信樹、米田久志、澤田将貴、古野正晃
37PR8-3

Neutron Radiography on Tubular Flow Reactor for Supercritical Hydrothermal
Synthesis of Nanoparticles

T. Tsukada, K. Sugioka, M. Kubo, K. Ozawa, S. Takami 1,
T. Adschiri2, K. Sugimoto3, N. Takenaka3, Y. Saito4
and Y. Kawabata4

in supercritical water. The size distribution of nanoparticles in (b) is much broader than those in (a), and the average sizes and the CV values of synthesized nanoparticles in (a) is smaller than those in (b). Here, the average
size of an octahedral particle was defined by (ls)1/2 withthe lengths of major and minor axes, l and s, of particle.
Such size distribution dependence of nanoparticles onreactor configuration is due to the difference in flow andthermal fields in the reactors. As the results of neutron
radiography show, the stream of supercritical waterflowing down through the vertical tube penetrates into
the horizontal tube, and a thermally, density-stratified
layer is generated in the horizontal tube of (a), while itseems from the temperature distributions in (b) that
thermal buoyancy convection occupies the vertical tube
just above the T-junction.

Dept. of Chemical Engineering, Tohoku University
1
IMRAM, Tohoku University
2
WPI-AIMR, Tohoku University3
Dept. of Mechanical Engineering, Kobe University
4
RRI, Kyoto University
INTRODUCTION: Recently, a variety of metal-oxide
nanoparticles have been synthesized by supercritical hydrothermal synthesis [1]. For the design and optimization of the process, it is important to acquire the correctknowledge about the mixing behavior of cold aqueous
feed solution and supercritical water in a hydrothermal
reactor. Therefore, we used neutron radiography to visualize the flow in a tubular flow reactor for supercriticalhydrothermal synthesis, and investigated the effects ofthe flow rates of two fluids and reactor configurations on
the mixing behavior in the reactor [2-4]. In this work,
CeO2 nanoparticles were actually synthesized by supercritical hydrothermal synthesis under the same conditions
as those in neutron radiography, and then the size distributions of synthesized nanoparticles were discussed
comparing with the flow and thermal fields observed byneutron radiography.

CONCLUSIONS: The relationship between the size
distributions of synthesized nanoparticles and the mixing
behaviors of the metal salt aqueous solution and supercritical water in the reactor was clarified by comparing
between the results of supercritical hydrothermal synthesis and neutron radiography in the reactor.
REFERENCES:[1] T. Adschiri et al., Green Chemistry, 13 (2011) 1380.
[2] S. Takami et al., J. Supercrit. Fluids, 63 (2012) 46.
[3] N. Takenaka et al., Phys. Procedia, 43 (2013) 264.
[4] K. Sugioka et al., AIChE J., 60, (2014) 1168.

EXPERIMENTS: The tubular flow reactor, which wascomprised of a Swagelok union tee and SUS316 tubes
whose outer diameter and wall thickness were 1/8 inch
and 0.71 mm, respectively, was used for synthesizing
CeO2 nanoparticles. Two streams of 10 mM Ce(NO3)3
aqueous solution and supercritical water were mixed andreacted at the T-junction in the reactor under approximately 25 MPa. The size distributions and average diameters of synthesized nanoparticles were evaluated using
SEM (S-4800, Hitachi High-Technologies Co., Japan).
Neutron radiography of the tubular flow reactor was
the same as that in our previous works [2-4], where athermal neutron beam emitted from the B4 port in KUR
was used. The imaging method of neutron radiography
and subsequent analysis of the images were also similar
to those in our previous work [3].
RESULTS:
Figures 1 (a) and (b) shows SEM images
and size distributions of nanoparticles synthesized using
tubular flow reactors with two different configurations,when the flow rates of supercritical water and Ce(NO3)3
aqueous solutions were 8.0 and 1.0 g/min, respectively.
In the figures, the temperature distributions obtained byneutron radiography are also shown. Octahedral CeO2
nanoparticles are found to be synthesized hydrothermally

Figure 1 SEM images and size distributions of synthesized nanoparticles, and temperature distributions observed by neutron radiography.

採択課題番号 26P8-3 中性子ラジオグラフィを利用した超臨界水反応場の in-situ 観察 プロジェクト（東北大院・工）塚田隆夫、杉岡健一、久保正樹、小澤恭兵、（東北大・多元研）高見誠一、（東北
大・WPI）阿尻雅文、（神戸大院・工）杉本勝美、竹中信幸、（京大・原子炉）齊藤泰司、川端祐司
38PR8-4

Neutron imaging and optics development using simulation of VCAD Systems

Y.Yamagata*1, S.Morita*1,J.Guo*1, J.Kato*1, H.Yokota*1,
T.Sera*1*2, Y.Kawabata*3, Y. Saitoh*3, M.Hino*3,
M.Sugiyama*3 ,D.Ito*3

RESULTS:
Fig. 1 shows the photo of the ellipsoid mirror through the
manufacturing process. Fig.2 shows the beamline setup
for ellipsoid mirror testing. The beam cam through pinhole (1mm) and U-shaped slit to eliminate the neutron
beams that will not reflect on the mirror surface. The focused beam is detected by RPMT detector. It was possible to detect neutron beam focusing using this small mirror as shown in Fig.3. Focusing performance using
VCAD software will be conducted in the near future.

RIKEN Center for Advanced Photonics, RIKEN*1,
Osaka University*2, Kyoto University Research Reactor
Institute*3

INTRODUCTION:
VCAD System is a cluster of software codes, which cangenerate "real" object model in a computer and perform
various numerical simulation. Those software codes include geometry conversion and input tools, 3D visualization, segmentation and mesh-generation tools, and various FEM-based simulation tools. The authors have been
applied the neutron radiography data to VCAD systems
to generate 3D geometry data and FEM analysis. Those
software also include a simulation code for "real" opticalcomponents. We did a consideration about possible application of neutron radiography for the production process visualization for glass press mold lens and also conducted focusing experiments of small rotational ellipsoid
mirror.

Fig.1 Manufactured ellipsoid mirror (a)aluminum
substrate (b)NiP plated (c)polish finished
L = 2.5 m
PinholeSlit

Chopper
Neutrons

RPMT

EXPERIMENTS:(1)Consideration of visualization of molding process
It was not possible to carry out a neutron radiography,
but we have considered the possibility of neutron radiography to visualization of glass molding process ofaspherical lens. Many lenses for digital cameras today
include at least a few aspherical lenses. Those asphericallenses are manufactured by glass press molding usingtungsten-carbide molding die at very high temperature of
500 to 900 degree. Since the process is done with hightemperature inside tungsten carbide die, it was not possible to visualize the process. Total cross section of tungsten (W) is 23.1 for thermal neutron and considering thatmost glass material contain boron which has very highcross section, it may be possible to visualize the molding
process through tungsten carbide die.
(2) Neutron beam focusing experiment
To manufacture a neutron focusing mirror with relatively lower cost and manufacturing time, the authors
have started the development of neutron focusing mirror
using metallic substrate.[1] The advantage of metallic
substrate are easier mechanical handling and shorter
manufacturing time. A 100mm rotational ellipsoid mirror was fabricated and focusing performance was tested
at CN-3 port.[2]Goniometer stage(6-axis)Ellipsoidal focusing mirror(a=1250, b=7)
Rail

Fig.2 Experimental setup for neutron focusing experimenta. Focusing spotc. 250 mm away from b. mirror-to-detector
mirror center
distance (625 mm )d. Direct beamfrom U slit

Fig.3 Focusing experiment result
REFERENCES:[1] S.Takeda, H.Ohno, H.Sato, M.Furusaka, S.Morita,
Y.Yamagata, M.Hino, "Development of an ellipsoidal
neutron supermirror with metal substrate", International
Workshop on Neutron Optics and Detectors, July (2013)[2] J.Guo, S.Takeda, S.Morita, M.Hino, T.Oda, J.Kato,
Y.Yamagata, and M.Furusaka, "New Fabrication Method
for an ellipsoidal neutron focusing mirror with a metal
substrate", Optics Express, Vol.22 No.20 DOI:
10.1364/OE.22.024666 (2014)

採択課題番号 26P8-5

中性子ラジオグラフィによる工業製品の内部情報取得とVCAD システムによるシミュレーション（京大・原子炉）齊藤泰司、川端祐司、杉山正明、日野正裕、伊藤大介（理研）山形豊、森田晋也、横田秀夫、世良俊博、加藤純一、池上祐司

39

プロジェクトPR8-5

Evaluation of the Moisture Movement in High-Performance
Concrete Subjected to Heating

M. Kanematsu1, S. Bae1, T. Koyama1, R. Inose1,
N. Tuchiya2, M. Tamura3, Y. Nishio3, T. Noguchi3
D. Ito4 and Y. Saitou4(a)1

Department of Architecture, Tokyo University of Science
Building Research Institute, Material Study Group3
Department of Architecture, The University of Tokyo
4
Research Reactor Institute Kyoto University

2

INTRODUCTION: High-performance concrete (HPC)
has low water-to-binder ratio and it is vulnerable to the fire
exposure, resulting in the explosive spalling of HPC surface at the early stage of fire. The spalling phenomena has
been explained to occur due to the moisture pressure accumulated inside the pore of HPC [1]. However, the actual
mechanism of the spalling has not been fully understood.
To understand the detailed mechanism of spalling in HPC,
2-dimensional moisture movement in HPC subjected toheating was quantitatively assessed in this study.
EXPERIMENTS: The concrete specimen (100×100×20mm3) with water-to-binder ratio of 18 % was prepared.
The initial moisture contents of the specimen was 14.1 %and the heating condition referred to the previous work[2].The TNRF in the B-4 beam-line of neutron flux
1×107n/cm2 was utilized for neutron radiography and thenoise pixel in the images deviating more than 10 grayscalevalues were replaced by the median value of the pixels
around the circle with 2-pixels radius.
RESULTS: Fig.1 presents 2-dimensional distribution ofdifferential moisture contents of paste in the specimen perunit volume. The correlation between the change of watercontent and the intensity of transmitted neutron was examined using specimens with predetermined specific watercontents. As shown in Fig.1, the moisture condensed areas
were observed at the boundary of dried areas, moving up
to the top with the temperature elevation. This phenomenon was also confirmed in our previous work, in the caseof high strength mortar [2]. Furthermore, the presence ofmoisture condensed areas was observed around the coarse
aggregates and the holes created for the internal temperature measurement, which is in good agreement with theprevious numerical model [4]. The interfacial transitionzone around the coarse aggregates is assumed to provide
the space that the condensed moisture can passthrough.The explosive spalling occurred for two times, at
1m26s and 1m27s, respectively. In the area of 0 to 5 mmfrom heating surface, moisture content increase was monitored with the value of 5.0×102 g/cm3 6.0×102 g/cm3 ateach spalling. The influence of vapor pressure induced bymoisture movement on the spalling phenomena of HPC
will be further investigated in the future.
REFERENCES:

(b)

(c)

Fig.1 Two-dimensional distribution of differential moisture contents of paste of HPC per unit volume at (a) 1
min, (b) 4 min, and (c) 8 min after heating[1] T.Z.Harmathy, ASTM, Philadelphia, No.385, 75-95[2] M.kanematsu et al, PJCI, vol36, No.1, 2014[3] J. Zhao, Cem. Concr. Res., 65, 64-75, 2014

採択課題番号26P8-10 高温加熱環境下における高強度コンクリートの水分移動の研究 プロジェクト（東理大・理工）兼松学、Sungchul Bae、小山拓、猪瀬亮（建研・材料）土屋直子（東大・工）田村政道、西尾悠平、野口貴文（京大炉）伊藤大介、齊藤泰司

40

PR8-6

Effect of Gravity on Coolant Distribution in FGHP Heat Spreader

K. Mizuta, Y. Saito 1, D. Ito 1
Faculty of Engineering, Kagoshima University
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Recently, the importance of thermal management in electronic devices has become muchhigher than ever, because the lack in cooling ability insuch devices leads to various reliability problems and low
working efficiency. Particularly, in a light-emitting diode(LED) array, non-uniform temperature distributions
caused by poor heat spreading ability of its substrate ruins the quality of lightning, because the light emitting
efficiency of LED gets lowered with higher working
temperature. To tackle with such problems in thermal
management, vapor chambers would be one of the hopeful candidates as the substrate for its higher effective
thermal conductivity compared with metal heat spreaders[1]. In an ordinary vapor chamber, however, it has beenreported that the heat transfer characteristics are strongly
affected by its installation posture, because the coolant
circulation inside the vapor chamber is strongly affectedby the gravity, which spoils the adoption of vapor chambers for the LED substrate. The authors have been trying
to solve such problems by utilizing a newly developed
vapor chamber called FGHP which is manufactured by
precise etching technique by Molex Kiire Co., Ltd. located in Kagoshima, Japan. In this study, we investigated
the gravitational effects on the coolant distribution in the
FGHP by using neutron radiography at the Kyoto University Research Reactor (KUR).

Fig. 1. Variation of the liquid thickness in the wick areawith input power.
Neutron imaging of the sample was performed at the 1
MW operation mode of the KUR and the exposure timewas 300 s. Neutron images of the sample were utilized to
calculate liquid thickness in the FGHP. The effect ofgravity on the coolant distribution was evaluated by thecalculated liquid thickness in the wick area at different
positions as follows:
1. Vertical position 1 (Top),
2. Vertical position 2 (Bottom),
3. Horizontal position 1 (Left),
4. Horizontal position 2 (Right).
Interrogation window size was 0.41.5 mm2 at each position.

EXPERIMENTS: Experiment was conducted at theE-2 port of the KUR, where the thermal neutron flux atthe sample position was about 3105 cm2s at 5 MW operation. The size of the test sample of FGHP heat spreader
was 65 mm square and 2 mm thick. The test sample wasset vertically, which means that its bottom and top plate
was placed parallel to the gravitational direction. A ceramic heater of 25251.75 mm3 was attached to thecentral part of the bottom plate as a heat source, and the
top plate was cooled by three pin-fin type aluminum heatsinks of 3535 mm2 under natural convection conditions.
K-type thermocouples were utilized to measure both thesurface temperature of the heat spreader and the atmospheric temperature to estimate the thermal resistance of
the FGHP. A CCD camera (BU-53LN, BITRAN Co.
Ltd.) was utilized, which has 4008×2672 pixels and
6
LiFZnS (50 m thickness) was used as a scintillator
screen. The spatial resolution was 9.0 μm/pixel at thepresent system setup, however, the effective spatial resolution was about 50 μm/pixel due to the scintillator
screen characteristics.

採択課題番号 26P8-11

RESULTS: Figure 1 shows the variation of liquid
thickness with heat input. As shown in Fig. 1, the measured values of the liquid thickness in the wick area takethe smallest at the top and the largest at the bottom positions. The measured values range from 200 to 480 m
and increases along with the gravitational direction.
However the liquid thickness remains nearly constantregardless of the heat input. From the design of the inner
structure of the FGHP heat spreader, the maximum liquid
thickness in the wick area can be estimated as 0.6 mm(about 0.1 mm in the middle plates and 0.5 mm in the top
and the bottom plates), therefore, at least 0.1 mm thickliquid layer would be considered to cover the surface ofthe middle plates as the wick structure, which may suggest the surface of the whole wick area does not dry out
even when the FGHP is installed in the vertical posture.
REFERENCES:[1] J. C. Wang, Int. J Heat and Mass Trans., 53 (2010)
3990-4001.

フラットヒートパイプ型ヒートスプレッダ内部における冷媒挙動に関する研究（鹿児島大・工）水田 敬（京大・原子炉）齊藤 泰司、伊藤 大介
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プロジェクトPR8-7

Study on Visualization of Organic Materials between Metals
for Advance of Industrial Products

K. Hirota1, A. Uritani, K. Watanabe, A. Yamazaki,
D. Sugimoto, Y. Kiyanagi, Y. Shiota, H. M. Shimizu1,
G. Ichikawa1, M. Kitaguchi2, Y. Saito3
Graduate School of Engineering, Nagoya University
1
Graduate School of Science, Nagoya University
2
Kobayashi-Maskawa Institute, Nagoya University
3
Research Reactor Institute, Kyoto University
INTRODUCTION: The machinery industry products
including automobile and aircraft are progressing to highperformance and high precision. One of the desired technique in these development fields of state-of-art technology products is visualization of organic film (oil film
grease, etc.) exist between metals. In the present work we
explore the possibility of observation of the characteristics(shape, nature and the distribution of thickness) of theorganic skin and its dynamic changes.

Fig. 1. Neutron radiography image of the bearings.
Half of these bearings are removed the grease.

EXPERIMENTS:
The measurement was done at E2
beam port in the reactor room. Bearings and an oil pump
are using for the sample materials. The CCD system is
Bitran BU-53LN and the scintillator is 6Li/Zns(Ag) of
thickness 200m, which is prepared RIKEN group andnormally equipped at E2. The neutron (static) radiography image and CT reconstruction images were taken
for both bearings and oil pomp. The CT reconstruction
system is also equipped at E2. The typical exposure timeis one minute for static image in 1 MW mode. This exposure time is decrease to 1/5 at 5MW mode. In the caseof CT measurement, 30 seconds exposure time and 300
images, which are corresponding to 0.6-degree sample
rotation step, are taken.

Fig. 2. CT reconstruction image. Black-and-white
shade is inverted to fig. 1.

RESULTS: Figure 1 shows the neutron radiography
image of bearings. These bearings are all commercial
products. Half of these bearings are removed grease.
White color area means that the neutron beam is easilytransmitted, and black area means absorption. Neutron
beam is expected to be well aborted by grease because ofincluding of hydrogen. Clear grease image were available
to find by comparing the picture between with and without grease. Figure 2 shows the CT reconstruction imageof bearing include grease. Black-and-white shade is inverted to fig. 1. White area indicated the grease in thecase of fig. 2. The grease skin is available to see between
the boll and the frame of the bearing.
We want to observe how to move the grease with bearing rotation as next plan.

採択課題番号 26P8-12

工業製品の高度化に資するためのプロジェクト
金属間有機物の可視化に関する研究（名古屋大・工）瓜谷章、渡辺賢一、山崎淳、杉本大、鬼柳善明、塩田佳徳、（名古屋大・理）
清水裕彦、広田克也、市川豪、（名古屋大・KMI）北口雅暁、（京大・原子炉）齊藤泰司
42

PR8-8Visualization of Flow Inside Fine Scale Wick of Heat Pipe

Y. Tsuji, T. Ito, M. Ogasawara, S. Yanagisawa,
M. Tamaki1, D. Ito2 and Y. Saito2
Graduate School of Engineering, Nagoya University
1
Department of Energy Engineering and Science
Graduate School of Science, Kyoto University
2
Research Reactor Institute, Kyoto University
INTRODUCTION: We study the heat transfer process
on the solid surface covered with liquid water. It is notclearly understand how the heat transfer is enhanced bychanging the condition of solid surface, characteristics ofliquid and flow conditions. We study the heat pipe (Fig.1)
as the simple equipment to study the heat transfer process,and the following points are focused. (1) Character ofsolid surface is changed, such as a water-repellent coat, ahydrophilic coat, and/or a monomolecular film are added
over the solid surface. (2) To change the solid surface
condition as a complicated shape (wick). Such as porous
media is attached on the surface and visualize the boilingprocess inside it. The boiling process is significantly affected by a porous shape and surface condition. (3)Heat
transfer is measured independently, and it is comparedwith boiling process inside the porous media is visualized
by NRG.
The purpose of this study is to enhance the heat transfer
and understand its physical process by analyzing the visualized images by NRG.

Fig.2 Neutron radiography image. (a) air=0ml,(b)air=5ml, (c)air=10ml.
RESULTS: The neutron radio grapy images are shownin Fig.2. We hope to observe the air, vapor and waterphases inside the heat pipe, however it was difficult todistinguish them clearly. The water phase (black) is suppressed in (c) compared with (a) condition. This may be
due to the increase of vapor pressure by adding the air. As
the heat pipe is slightly tilted along the side wall, we canobserve the thin liquid film flowing from top to down.
This is caused by the liquid (water) condensed at the upper region and return to the bottom. On the left-side wall,the liquid film is thicker than that of right wall.
For the qualitative analysis from the digitized image
intensity, the effect of aluminum wall is removed. We
visualized the heat pipe, which does not contain theworking fluid. By using this calibration image, background image is subtracted, that is usually adopted as
NRG procedure. Figure 3 shows the averaged intensity
profiles along the vertical direction of heat pipe. The intensity corresponds to the ratio of water averaged overthe cross direction. The different colors show the conditions (a), (b), and (c), respectively. At the bottom region
close to heater, the intensity of (a) shows the smaller value than other conditions. This indicates the water region
remains much more in (a) condition. However, we can
not distinguish the vapor and air regions. For the final
purpose of our research, the vapor region should be distinguished from other states (water and air phases). The
present techniques are revised in the next stage.

EXPERIMENTS: House-made heat pipe is operated
with supplying the heat by the Peltier module. We change
the conditions of heat transfer with monitoring the NRG
image. The heat pipe is made of aluminum, whose dimension is 20×110×110mm. Heater power is varied
from 6 W to 30W, and the temperature of heater sectionchanges from 40℃ to 70℃. The maximum inside pressure is 36 kPa.
In this measurement, we have to check the basic performance of NRG technique for observing the air, vapor
and water states and their motions. Working fluid is water(20ml), and three different amounts of air (0, 5, 10ml) aresupplied inside the heat pipe. The E2 beam port was used
for NRG experiments.

Fig.3 NRG intensity profiles along the heat pipe.

Fig.1 Schematic view of experimental setup

採択課題番号 26P8-13
微細ウイック内流動のＮＲＧによる可視化に関する研究（名大院工）辻義之、伊藤高啓、小笠原克、玉置昌義（京大・原子炉）齊藤泰司
43

プロジェクト