CO3-1

Development of In-reactor Observation System Using Cherenkov Light (VI)

T. Takeuchi, K. Yamamoto, N. Otsuka, H. Shibata,A. Shibata, N. Takemoto, K. Tsuchiya, T. Sano1,H. Unesaki1, Y. Fujihara1, Y. Takahashi1
and K. Nakajima1

the change rates of the brightness are larger and smaller
than that of the total output power, respectively. The difference in the change rate between the TC and D2O sides
is thought to be due to an inhomogeneous distribution ofoutput power, resulting in the difference in the amount ofthe Cherenkov light. On the other hand, the absolute value of the brightness of the TC side was smaller than thatof the D2O side at from 1 to 2 MW. A possible explanation is that the shadow of the control-rod guide tubes andthe other irradiation equipment were included in image ofthe CCD camera. To suppress the effect of the shadow on
the analyses of the brightness, the observations of theCherenkov light from various positions using a numberof cameras might be required.

Neutron Irradiation and Testing Reactor Center, JAEA
1Research Reactor Institute, Kyoto University
INTRODUCTION: The surveillance system which
can visualize and quantitatively evaluate reactor statuses
will contribute to reactor operation management. We
started the development of the on-line reactor core imaging system using Cherenkov light[1] in 2009. Previously,
the total reactor power of the KUR can be estimated using the CCD camera by the method of dissolving the total
image brightness to the RGB brightness components[2]. In
this study, the correlation between the reactor power andthe image brightness of the Cherenkov light from a specific fuel element was evaluated in an effort to evaluate
the output power of each fuel element.

CONCLUSION: As part of the development of thevisible on-line core surveillance system, the Cherenkov
light at the core of KUR observed by a CCD camera wasanalyzed on the correlation between the image brightnessof the Cherenkov light and the output power about a specific fuel element. The results indicate that the inhomogeneous distribution of output power and the shadow of
the control-rod guide tubes and the other irradiationequipment have significant effects on the brightness of
the Cherenkov light. These effects could be suppressedby using a number of cameras located at various positions.

EXPERIMENTS: The CCD camera (AEC-100ZL, Q·IInc.) was inserted into core-observation pipe of KUR
during increasing the reactor power from 1 to 5 MW. The
output of the CCD camera was collected by an image
recorder. The Cherenkov light from the target fuel element shown in fig. 1 was analyzed. The brightness signalof the output image from the CCD was dissolved to RGB
color signals (R:700nm, G:546.1nm, B:435.8nm)[3]. TheR component without halation was used to correct thetotal image brightness.

REFERENCES:[1] J.V. Jellry, Cherenkov Radiation and its Applications(Pergamon, New York, 1958).
[2] N. Otsuka, et al., KURRI Progress Report, (2013) P.
215.
[3] Commission internationale de l'Eclairage proceedings,
1931, Cambridge.

RESULTS: Figure 2 shows the results of the analysesof the Cherenkov light from the TC and D2O sides of thetarget fuel element. Although the averaged brightnesschanges at an almost same rate as that of the total output
power, at the TC and D2O sides of the fuel element,

TC sideD2O sideFig. 2. The change rate of the brightness of theCherenkov light from the target fuel element withthe reactor power.

Fig. 1. The array of the fuel elements at the core ofKUR. The red boxed fuel is the target one. The blackband at the middle of the fuel element is the handle.

採択課題番号 26040 チェレンコフ光を用いた試験研究炉の炉内監視手法の研究開発 通常採択
（原子力機構）土谷邦彦、武内伴照、大塚紀彰、柴田裕司、柴田 晃、山本圭一、竹本紀之（京大・原子炉）中島 健、宇根崎博信、佐野忠史、藤原靖幸、高橋佳之
108CO3-2 Neutron Irradiation Effect of High-density MoO3 Pellets for Mo-99 Production (2)After the dissolution of irradiated MoO3 pellets andextraction of 99mTc solution, 99Mo and 99mTc activities
were measured in the Mo solution and 99mTc solution by
the germanium detector. From the result of the -ray
spectrum of Mo solution and 99mTc solution, the ratio of
measured value and calculated value (M/C) was 1.05 andit was confirmed that the calculated 99Mo marched themeasured one within an error of ±5% by the previous
method [3]. On the other hand, 92mNb observed in theMo solution as impurities. 92mNb was not measured in
the 99mTc solutions. Table 2 shows the result of 99mTc
recovery rates from the Mo solution. The recovery rateof the 1st and 2nd runs achieved the target values (>80%).
The 3rd and 4th runs were less than 60%. In this experimental, different MEKs were used for the extraction tests
and it seems that the 99mTc recovery rate affected purityof MEK.
Impurities such as Al, Mo and MEK, radiochemical
purity and radionuclidic impurity were measured with the99m
Tc solution in the 1st run and the high purity 99mTc solution was obtained by this method.

K. Nishikata, T. Ishida, M. Yonekawa, Y. Kato,M. Kurosawa, A. Kimura, Y. Matsui, K. Tsuchiya,
T. Sano1, Y. Fujihara1, Y. Takahashi1 and J. Zhang1
Neutron Irradiation and Testing Reactor Center, JAEA
1
Research Reactor Institute, Kyoto University
INTRODUCTION: As one of effective applications ofthe Japan Materials Testing Reactor (JMTR), JAEA has aplan to produce 99Mo by (n, γ) method ((n, γ)99Mo production), a parent nuclide of 99mTc [1]. In this study, preliminary irradiation test was carried out with thehigh-density molybdenum trioxide (MoO3) pellets in thehydraulic conveyer (HYD) of the Kyoto University Research Reactor (KUR) and the 99mTc solution extracted
from 99Mo was evaluated.
EXPERIMENTS:
The high-density MoO3 pellets
were fabricated by the Plasma Sintering Method [2].
Dimension and density of MoO3 pellets were 18×10 mm
and about 92.5%T.D., respectively. The MoO3 pellets
were irradiated in the HYD of the KUR. Before theirradiation test, neutron flux in the HYD was measured
with the dosimeters (In foil and In-Ni foil with Cd canning). Table 1 shows the irradiation conditions of MoO3pellets in the HYD. After the irradiation tests, the irradiated MoO3 pellets were transported from KUR toJMTR-HL. The irradiated pellets were dissolved with6M-NaOH solution in the Lead Cell and the 99mTc wasextracted from the Mo solution by the solvent extraction
method using methyl ethyl ketone (MEK).

Result of 99mTc recovery rates from the Mosolution
Activity of 99mTc
Recovery rate
No.
(Bq)
(%)
1st run1.09 × 109
82.3
2nd run8.53 × 108
95.7
rd3 run3.09 × 108
56.5
th84 run
2.41 × 10
55.1

Table 2Table 1 Irradiation conditions of MoO3 pellets
Items
Thermal power

1 MW

Thermal neutron flux

1.82 × 10 ± 4.18 × 1015 m-2s-1

Epithermal neutron flux

7.08 × 1016 ± 2.29 × 1015 m-2s-1

Fast neutron flux

7.13 × 1016 ± 1.85 × 1015 m-2s-1

Irradiation time
Irradiation temperature

CONCLUSION: After the irradiation test of thehigh-density MoO3 pellets in the KUR, 99mTc was extracted from the Mo solution and the recovery rate of99m
Tc achieved the target values. The 99mTc solution
also got the value that satisfied the standard value for99m
Tc radiopharmaceutical products by the solvent extraction method.

Values17

3.2 hREFERENCES:[1] K. Nishikata, et al., Fabrication and Characterizationof High-Density MoO3 Pellets, Proceedings of 2012
Powder Metallurgy World Congress & Exhibition(2012) CD-ROM.
[2] K. Tsuchiya, et al., Status of 99Mo-99mTc Production
Development by (n, γ) Reaction, JAEA-Conf
2011-003（2011）.
[3] K. Nishikata, et al., Neutron Irradiation Effect ofHigh-density MoO3 pellets for Mo-99 Production,KURR Progress Report 2013, p242.

below 90°C

RESULTS: After the irradiation test, all of the diffraction peaks corresponding to the orthorhombic crystalstructure (-MoO3) were assigned to MoO3 appeared in
the irradiated MoO3 pellet. The Grain sizes of MoO3 pellet before/after neutron irradiation were almost identical(approx. 1μm). The results suggest that No change ofcrystal structure and grain size was observed in the MoO3
pellets irradiated at low temperature and low fluence.

採択課題番号 26041
高密度 MoO3 ペレットの照射効果に関する研究（JAEA）西方 香緒里、石田 卓也、米川 実、加藤 佳明、黒澤 誠、木村土谷 邦彦（京大・原子炉）佐野 忠史、藤原 靖幸、高橋 佳之、張 倹
109通常採択
明博、松井 義典、