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JAEA Reports

Activity median aerodynamic diameter relating to contamination at Plutonium Fuel Research Facility in Oarai Research and Development Center; Particle size analysis for plutonium particles using imaging plate

Takasaki, Koji; Yasumune, Takashi; Hashimoto, Makoto; Maeda, Koji; Kato, Masato; Yoshizawa, Michio; Momose, Takumaro

JAEA-Review 2019-003, 48 Pages, 2019/03

JAEA-Review-2019-003.pdf:3.81MB

June 6, 2017, at Plutonium Fuel Research Facility in Oarai Research and Development Center of JAEA, when five workers were inspecting storage containers containing plutonium and uranium, resin bags in a storage container ruptured, and radioactive dust spread. Though they were wearing a half face mask respirator, they inhaled radioactive materials. In the evaluation of the internal exposure dose, the aerodynamic radioactive median diameter (AMAD) is an important parameter. We measured 14 smear samples and a dust filter paper with imaging plates, and estimated the AMAD by image analysis. As a result of estimating the AMAD, from the 14 smear samples, the AMADs are 4.3 to 11 $$mu$$m or more in the case of nitrate plutonium, and the AMADs are 5.6 to 14 $$mu$$m or more in the case of the oxidized plutonium. Also, from the dust filter paper, the AMAD is 3.0 $$mu$$m or more in the case of nitrate plutonium, and the AMAD is 3.9 $$mu$$m or more in the case of the oxidized plutonium.

Journal Articles

Development of a new detector system to evaluate position and activity of plutonium particles in nasal cavities

Morishita, Yuki; Yamamoto, Seiichi*; Momose, Takumaro; Kaneko, Junichi*; Nemoto, Norio

Radiation Protection Dosimetry, 178(4), p.414 - 421, 2018/03

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Plutonium dioxide (PuO$$_{2}$$) is used to fabricate a mixed oxide fuel for fast breeder reactors. When a glove box containing PuO$$_{2}$$ fails, such as by rupture of a glove or a vinyl bag, airborne contamination of plutonium (Pu) can occur. If the worker inhale PuO$$_{2}$$ particles, they deposit in the lung and cause lung cancer. The nasal smear and nose blow methods are useful for checking workers for PuO$$_{2}$$ intake in the field. However, neither method can evaluate the quantitative activity of Pu. No alpha-particle detector that can be used for direct measurements in the nasal cavity has been developed. Therefore, we developed a nasal monitor capable of directly measuring the activity of Pu in the nasal cavity to precisely evaluate the internal exposure dose of a worker. Prismatic-shaped 2$$times$$2 acrylic light guides were used to compose a detector block, and a ZnS(Ag) scintillator was adhered to the surface of these light guides. Silicon photomultiplier (SiPM) arrays with 8$$times$$8 channels were used as a photodetector. Actual PuO$$_{2}$$ particles were measured using the nasal monitor. The nasal monitor could be directly inserted in the nasal cavities. The activity distribution of Pu was obtained by the nasal monitor. The average efficiencies in 4$$pi$$ were 11.43% and 11.58% for the left and right nasal cavities, respectively. The effect of $$gamma$$ and $$beta$$ rays on the detection of the alpha particles of Pu was negligible. The difference in the measured Pu activity between the ZnS(Ag) scintillation counter and the nasal monitor was within 4.0%. The developed nasal monitor can solve the uncertainty problem encountered with the nasal smear and the nose blow methods. We expect this monitor to be useful for accurately estimating the internal exposure dose of workers.

Journal Articles

Performance of Panasonic ZP-1460 electronic personal dosemeter under exposure conditions likely to be found at Fukushima Daiichi Nuclear Power Plant

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya; Momose, Takumaro

JPS Conference Proceedings (Internet), 11, p.070008_1 - 070008_6, 2016/11

Journal Articles

Results of whole body counting for JAEA staff members engaged in the emergency radiological monitoring for the Fukushima nuclear disaster

Takada, Chie; Kurihara, Osamu*; Kanai, Katsuta; Nakagawa, Takahiro; Tsujimura, Norio; Momose, Takumaro

NIRS-M-252, p.3 - 11, 2013/03

A massive earthquake and tsunami on March 11, 2011 resulted in an enormous amount of release of radioactivity to the environment. On the day after the earthquake occurrence, Japan Atomic Energy Agency (JAEA) started emergency radiological monitoring. The measurements with whole body counter (WBC) for the staff members who had returned from Fukushima started at the end of March. The measured activity of $$^{131}$$I due to inhalation for emergency staff varied from LLD to 7 kBq, which corresponded to a range of estimated initial intakes of $$<$$ 1 to 60 kBq when extrapolated back to the date on which the staff started the operation in Fukushima. The measured activity of $$^{134}$$Cs and $$^{137}$$Cs were both in the ranges of LLD - 3 kBq. The range of initial intake of $$^{137}$$Cs to $$^{131}$$I was 11 when taking a median from all the measurements. The maximum committed effective dose of 0.8 mSv was recorded for a worker, a member of the 2nd monitoring team dispatched from March 13 to 14.

Journal Articles

Measurements of $$^{131}$$I in the thyroids of employees involved in the Fukushima Daiichi Nuclear Power Station accident

Kurihara, Osamu*; Kanai, Katsuta; Nakagawa, Takahiro; Takada, Chie; Tsujimura, Norio; Momose, Takumaro; Furuta, Sadaaki

Journal of Nuclear Science and Technology, 50(2), p.122 - 129, 2013/02

 Times Cited Count:5 Percentile:52.28(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Special environmental monitoring around Tokai-mura after the accident of the Fukushima Dai-ichi Nuclear Power Station

Fujita, Hiroki; Nagaoka, Mika; Kono, Takahiko; Takeyasu, Masanori; Kawasaki, Masatsugu; Okura, Takehisa; Tsujimura, Norio; Sumiya, Shuichi; Momose, Takumaro; Furuta, Sadaaki

Proceedings of 13th International Congress of the International Radiation Protection Association (IRPA-13) (Internet), 7 Pages, 2012/05

The nuclear accident at Fukushima Dai-ichi Nuclear Power Station of Tokyo Electric Power Co. (TEPCO) was caused by the Tohoku District-off the Pacific Ocean Earthquake. Various kinds of radionuclides were released from the power station right after the accident occurred and then reached our laboratories. Therefore, environmental monitoring was reinforced by observation of air absorbed dose rate, periodic collection of airborne dust, precipitation. The collected samples were used to determine radioactivity of $$gamma$$ ray emitters by High pure Germanium semiconductor detector. Moreover, rainwater and humidity were collected to do the usual routine monitoring. In some samples, $$^{90}$$Sr, $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs were detected with radioactivity released from the Fukushima station. In other samples such as seawater, seabed soil and etc., similar radionuclides were detected including the influence of the accident.

Journal Articles

Development of a microcalorimeter with transition edge sensor for detection of LX rays emitted by transuranium elements

Nakamura, Keisuke; Maeda, Makoto*; Yasumune, Takashi*; Maehata, Keisuke*; Ishibashi, Kenji*; Tanaka, Keiichi*; Umeno, Takahiro*; Takasaki, Koji; Momose, Takumaro

Radiation Protection Dosimetry, 146(1-3), p.88 - 91, 2011/07

 Times Cited Count:1 Percentile:87.48(Environmental Sciences)

A Transition Edge Sensor (TES) microcalorimeter has been developed for use as an energy dispersive X-ray spectrometer. A TES microcalorimeter is a thermal detector used to measure the energy of an incident photon with increase in temperature. In this work, a TES microcalorimeter with a 5$$mu$$m Au absorber was developed for use in measuring LX rays emitted from transuranium elements. Furthermore, as a cooling system a dilution refrigerator utilizing a Gifford-McMahon refrigerator was used, which needs no liquid helium. The performance of the TES microcalorimeter was evaluated by measuring the LX rays emitted by an $$^{241}$$Am source. This system proved effective in the measurement of the LX rays because the full width at half maximum of the L$$_{beta1}$$X ray was about 80 eV.

Journal Articles

Development of new analytical method based on $$beta$$-$$alpha$$ coincidence method for selective measurement of $$^{214}$$Bi-$$^{214}$$Po; Application to dust filter used in radiation management

Sanada, Yukihisa; Tanabe, Yoichiro*; Iijima, Nobuo; Momose, Takumaro

Radiation Protection Dosimetry, 146(1-3), p.80 - 83, 2011/07

 Times Cited Count:0 Percentile:100(Environmental Sciences)

The radionuclide pair $$^{214}$$Bi and $$^{214}$$Bi which belongs to the uranium-series interferes with airborne radionuclide measurement, needed for the radiation management of a nuclear facility. Time intervals between $$^{214}$$Bi ($$alpha$$) and $$^{214}$$Po ($$beta$$) are much shorter than artificial radionuclides due to the short half-life of $$^{214}$$Po (164 $$mu$$s). Measurement of airborne radionuclides can subtract this background by the selective measurement of $$^{214}$$Bi-$$^{214}$$Po. The purpose of this study is to develop of a new analytical method (Time interval analysis: TIA) based on the beta-alpha coincidence method for selective measurement of $$^{214}$$Bi-$$^{214}$$Po. The developed method was applied to an actual dust-filter measurement.

Journal Articles

Radiation protection at nuclear fuel cycle facilities

Endo, Kuniaki; Momose, Takumaro; Furuta, Sadaaki

Radiation Protection Dosimetry, 146(1-3), p.119 - 122, 2011/07

 Times Cited Count:2 Percentile:77.85(Environmental Sciences)

JAEA Reports

Re-evaluation of a method for monitoring airborne radioiodine discharge and its contribution to development of an advanced method

Koarashi, Jun; Mikami, Satoshi; Miyauchi, Toru; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Nakada, Akira; Akiyama, Kiyomitsu; Momose, Takumaro

JAEA-Technology 2010-039, 34 Pages, 2010/12

JAEA-Technology-2010-039.pdf:1.13MB
JAEA-Technology-2010-039(errata).pdf:0.08MB

The current methodology for monitoring airborne radioiodine at the Tokai reprocessing plant (TRP) was reviewed, and some investigations were made to re-evaluate collection and measurement techniques in the methodology. The investigations focused particularly on: (1) in situ collection efficiency of an iodine sampler for $$^{129}$$I and its dependence on sampling flow rate; (2) evaluation of $$^{129}$$I and $$^{131}$$I activities collected in an activated charcoal cartridge; (3) $$^{129}$$I collection capacity of an activated charcoal cartridge under reprocessing off-gas conditions; and (4) real-time monitoring system for $$^{129}$$I in airborne effluent. The results obtained gave not only the validity of the TRP's monitoring method, but also technical aspects required for establishing a more reliable and effective monitoring method for radioiodine isotopes.

Journal Articles

Replacement of the criticality accident alarm system in the Tokai Reprocessing Plant

Sanada, Yukihisa; Ishii, Masato*; Hasegawa, Ichiro; Kanazawa, Nobuyuki; Chikazawa, Tatsuya*; Momose, Takumaro

NEA/CSNI/R(2010)4 (Internet), p.351 - 370, 2010/11

A criticality accident alarm system (CAAS) was installed in the 1980s as part of criticality safety management at the Tokai Reprocessing Plant (TRP) to reduce the chance of workers being exposed to radiation in the rare case of a criticality accident. From a compliance point of view processing at TRP cannot take place without the criticality monitoring provided by the CAAS. This paper gives an overview of the process of the CAAS being replaced as part of aging management.

Journal Articles

Radiation detection and measurement in patients contaminated with alpha emitters

Momose, Takumaro; Kurihara, Osamu; Takada, Chie; Furuta, Sadaaki

Proceedings of 1st International Symposium on Radiation Emergency Medicine at Hirosaki University, p.65 - 72, 2010/07

The basic principle of radiation control at plutonium facility such as characteristics of plutonium and relevant radionuclide which are operated in nuclear fuel cycle facilities is introduced and potential radioactive contaminations in accident is discussed. As a practice, decontamination procedure of skin at Tokai Reprocessing Plant, some of the operating principles and applications of various radiation detection and measurement instruments for contamination control and occupational monitoring for internal contamination are introduced. Special methods of measurement for alpha emitters for performing radiological monitoring such as radio autography of plutonium contamination on smear samples, nasal swab sampling and measurement, in vivo and in vitro analysis for plutonium and uranium have been improved and proven. The internal dose calculation code was originally developed in order to estimate retrospectively in case of accidental intake of plutonium.

JAEA Reports

Radioactive airborne effluent discharged from Tokai reprocessing plant; 1998-2007

Nakada, Akira; Miyauchi, Toru; Akiyama, Kiyomitsu; Momose, Takumaro; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Otomo, Hiroyuki*

JAEA-Data/Code 2008-018, 134 Pages, 2008/10

JAEA-Data-Code-2008-018.pdf:3.23MB

This report provides the data set of atmospheric discharges from Tokai reprocessing plant in Tokai-mura, Japan over the period from 1998 to 2007. Daily and weekly data are shown for $$^{85}$$Kr that is continuously monitored and for the other nuclide (Alpha emitters, Beta emitters, $$^{3}$$H, $$^{14}$$C, $$^{129}$$I, $$^{131}$$I) whose activities are evaluated based on weekly batch-samplings, respectively. The data contained in this report are expected to apply for studying the behavior of the radioactive airborne effluent in the environment.

Journal Articles

Replacement of the criticality accident alarm system in the Tokai reprocessing plant

Sanada, Yukihisa; Nemoto, Makoto*; Suzuki, Kei*; Kawai, Keiichi*; Momose, Takumaro

Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM), 7 Pages, 2008/10

The purpose of this study is to show the design principle and the determination procedures for the adequate relocation of the CADs in TRP. When the alarm trip point was 2.0 mGy/h, it is possible to detect a criticality accident even under conservative conditions (i.e. $$gamma$$: 10 m distances from the equipment to the CAD and 140 cm concrete shield between them; neutron: 15 m distances and both 60 cm concrete shield and 60 cm steel shield). Consequently, it was found the seven CADs at these locations could monitor PCDF adequately. This study was reflected in the determination of the new CAD location.

Journal Articles

Practical action levels for chelation therapy in plutonium inhalation using nose swab

Kurihara, Osamu; Takada, Chie; Takasaki, Koji; Ito, Kimio; Momose, Takumaro; Miyabe, Kenjiro

Radiation Protection Dosimetry, 127(1-4), p.411 - 414, 2007/11

 Times Cited Count:7 Percentile:48.51(Environmental Sciences)

Practical action levels for beginning chelation therapy to remove plutonium in the body are now under discussion in Japan since there has been no experience in administrating agents to a subject in accidental intake in Japan although a first commercial reprocessing plant is about to start operation. Recently, International Commission on Radiological Protection (ICRP) proposed some medical intervention levels for chelation therapy on ICRP Publication 96. These levels are determined based on internal dose however common monitoring methods such as lung counting or excreta analysis are not necessarily suitable in terms of both sensitivity and promptness. As an alternative, the authors paid attention to nose swabs and introduced the practical action levels.

Journal Articles

REIDAC; A Software package for retrospective dose assessment in internal contamination of radionuclides

Kurihara, Osamu; Hato, Shinji; Kanai, Katsuta; Takada, Chie; Takasaki, Koji; Ito, Kimio; Ikeda, Hiroshi*; Oeda, Mikihiro*; Kurosawa, Naohiro*; Fukutsu, Kumiko*; et al.

Journal of Nuclear Science and Technology, 44(10), p.1337 - 1346, 2007/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

In the case of internal contamination of radionuclides, it is necessary to perform internal dose assessment for radiation protection. For this purpose, the ICRP has given the dose coefficients and the retention and excretion rates for various radionuclides. However, these dosimetric quantities are calculated only in typical conditions, therefore, are not necessarily covered enough in the case of dose assessment in which specific information on the incident or/and individual biokinetic characteristics should be taken into account retrospectively. This paper describes a developed PC-based package of software REIDAC to meet the needs in retrospective dose assessment. REIDAC was verified by comparisons with dosimetric quantities given on the ICRP publications and several examples of practical use were also shown.

Journal Articles

Development of a neutron personal dose equivalent detector

Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie; Momose, Takumaro; Nunomiya, Tomoya*; Aoyama, Kei*

Radiation Protection Dosimetry, 126(1-4), p.261 - 264, 2007/08

 Times Cited Count:0 Percentile:100(Environmental Sciences)JP, 2005-183862   Patent publication (In Japanese)

The authors developed a new neutron measuring-instrument that was designed to measure neutron personal dose equivalent, $$H$$$$_{rm p}$$(10). This detector is composed a central thermal neutron detector, a core-polyethylene moderator, a front-hemispherical polyethylene moderator and rear-hemispherical boron-contained polyethylene absorber. Dimensions of each part were determined so as to provide energy- and angular-responses close to energy- and angular-dependencies of neutron $$H$$$$_{rm p}$$(10), based on the Monte Carlo calculations.

Journal Articles

Calculations of anisotropy factors for radionuclide neutron sources due to scattering from source encapsulation and support structures

Tsujimura, Norio; Yoshida, Tadayoshi; Momose, Takumaro

Radiation Protection Dosimetry, 126(1-4), p.168 - 173, 2007/08

 Times Cited Count:5 Percentile:59.28(Environmental Sciences)

The authors developed a model calculating angular neutron fluence distributions for radionuclide neutron sources which are heavily encapsulated or surrounded with some source support structures such as a source holder and a source movement system. These structures cause a highly anisotropic neutron fluence distribution, and hence it should be properly corrected for calibration of neutron measuring instruments. The calculations were made for two types of widely used neutron sources, $$^{241}$$Am-Be and $$^{252}$$Cf, by a combination of the in-house code simulating $$^{9}$$Be($$alpha$$,n) reactions and the Monte Carlo code MCNP4C. As a result, anisotropy factors in the direction perpendicular to the source capsule axis for bare neutron sources were evaluated to be 1.012, 1.030 and 1.035 for $$^{252}$$Cf in a standard Amersham X1 capsule, $$^{241}$$Am-Be in a X3 capsule and $$^{241}$$Am-Be in a X4 capsule, respectively. These values are in reasonable agreements with published data. In contrast, anisotropy factors for these neutron sources including support structures increased by approximately 10% due to scattering of neutrons.

Journal Articles

Development of $$^{241}$$Am lung monitoring system using an imaging plate

Hirota, Masahiro*; Kurihara, Osamu; Takada, Chie; Takasaki, Koji; Momose, Takumaro; Deji, Shizuhiko*; Ito, Shigeki*; Saze, Takuya*; Nishizawa, Kunihide*

Health Physics, 93(1), p.28 - 35, 2007/07

 Times Cited Count:4 Percentile:65.46(Environmental Sciences)

A new $$^{241}$$Am lung monitoring system without shielding was devised by using an imaging plate system. The Lawrence Livermore National Laboratory's realistic torso phantom containing a $$^{241}$$Am lung was covered by imaging plates sealed in lightproof bags. The imaging plate system displayed $$^{241}$$Am lung images characteristic of the lung shape of the torso phantom. The imaging plate system's lower detection limits of 14 Bq for 60 min exposure and 6 Bq for 300 min were the same levels as those of the phoswich detectors and the germanium detectors placed in shielded rooms. The imagingplate system for 60 min exposure detected about 2% of the annual limit of 740 Bq for $$^{241}$$Am inhalation. A lung monitoring system using imaging plates is applicable for $$^{241}$$Am lung monitoring.

121 (Records 1-20 displayed on this page)