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Journal Articles

Study on migration behaviour of $$^{237}$$Np and $$^{241}$$Am in near-surface environments

Tanaka, Tadao; Ya-Anant, N.*

Radiation Protection Dosimetry, 146(1-3), p.303 - 306, 2011/07

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

Laboratory scale experiments were performed to investigate migration behavior of $$^{237}$$Np and $$^{241}$$Am, which were deposited onto the ground surface from spent fuel reprocessing facilities, in near-surface environment. Column migration experiments were conducted by varying the volume of eluting solution, for a sandy soil and a reddish soil. There seemed to be two chemical species of $$^{237}$$Np in the sandy soil column; one is cationic and the other is particulate form. The particulates moved without significant interaction with the sandy soil. The sorption of cationic $$^{237}$$Np was controlled by both a reversible ion-exchange reaction and irreversible reactions. Most of $$^{241}$$Am formed rather large particulates and trapped in the sandy soil column. The $$^{237}$$Np and $$^{241}$$Am loaded into the reddish soil column moved deeper with increasing eluting volume. The sorption was mainly controlled by ion-exchange reaction. The migration behavior could be significantly evaluated by the distribution coefficient.

Journal Articles

WAZA-ARI; Computational dosimetry system for X-ray CT examinations, 1; Radiation transport calculation for organ and tissue doses evaluation using JM phantom

Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji*; Yoshitake, Takayasu*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Ban, Nobuhiko*; Kai, Michiaki*

Radiation Protection Dosimetry, 146(1-3), p.241 - 243, 2011/07

 Times Cited Count:16 Percentile:80(Environmental Sciences)

A web-system of WAZA-ARI is being developed to assess radiation dose to a patient in a Computed Tomography (CT) examination. WAZA-ARI utilizes a set of organ and tissue doses in a database for the dose assessment, according to the given resources with a consideration of the examination condition. The organ and tissue doses in the database have been derived with the Particle and Heavy Ion Transport code System, PHITS. Modeling of the patient was a significant issue in the radiation transport calculation. JM phantom, whose height (171 cm) and weight (65 kg) are near to those averaged over Japanese male adults, was incorporated to PHITS as a human model. Since JM phantom consisted of about 1 mm$$^{3}$$ size voxel, the shapes could be realistically reproduced even for small organs such as thyroid, adrenals. Masses of most organs could be also adjusted to the averaged values of Japanese male adults. In addition, our calculations introduced a new phantom without arms based upon JM phantom, because the patient usually puts arms toward the head direction in a torso examination. Some of organ doses calculated by JM phantom were compared with results, which were derived with a MIRD-type phantom. Differences could be seen in some organ doses between the phantoms, if photon attenuations in a shaping (Bow-tie) filter were taken into account to a source model in PHITS.

Journal Articles

WAZA-ARI; Computational dosimetry system for X-ray CT examinations, 2; Development of web-based system

Ban, Nobuhiko*; Takahashi, Fumiaki; Ono, Koji*; Hasegawa, Takayuki*; Yoshitake, Takayasu*; Katsunuma, Yasushi*; Sato, Kaoru; Endo, Akira; Kai, Michiaki*

Radiation Protection Dosimetry, 146(1-3), p.244 - 247, 2011/07

 Times Cited Count:16 Percentile:80(Environmental Sciences)

We are developing a web-based system, WAZA-ARI, for the dose calculation of patients undergoing X-ray CT examinations. Tissue doses were calculated in a Japanese adult male phantom (JM phantom) using a Monte Carlo code, PHITS, and the normalized dose coefficient data are stored as XML files. The system is implemented in Java on a Linux server running Apache Tomcat, which is accessed via a web browser over a network. Users are requested to choose scanning options and to input parameters in the data entry screen. The corresponding dose data are called upon input, and they are summed over the scan range specified by the user to estimate unit tissue doses. Tissue doses are computed based on the radiographic exposure (mAs), the beam pitch and air kerma at the beam center on the axis of rotation. Users can also use their own air kerma, CTDI vol and DLP values for the dose computation instead of the default setting. Although the dose coefficients are prepared for only limited CT scanner models currently, our system has achieved high usability and easy maintenance without commercial software. Possibility of further expansion for the practical application is also discussed.

Journal Articles

Impact of the introduction of ICRP publication 103 on neutron dosimetry

Sato, Tatsuhiko; Endo, Akira; Yasuda, Hiroshi*; Niita, Koji*

Radiation Protection Dosimetry, 146(1-3), p.183 - 185, 2011/07

 Times Cited Count:1 Percentile:11.72(Environmental Sciences)

A set of the conversion coefficients from fluence to the effective dose has been calculated for neutrons and protons over wide energy ranges based on the instruction given in ICRP 103, using the PHITS code. The calculated values are generally smaller than those based on ICRP Publication 60, predominantly owing to the revision of $$w$$$$_{R}$$ for those particles. The impact of the introduction of ICRP 103 on the dosimetry for high-energy particles will be discussed by comparing between the ICRP 103- and ICRP 60-based effective doses for aircrews as well as workers in high-energy accelerator facilities.

Journal Articles

Verification analysis of thermoluminescent albedo neutron dosimetry at MOX fuel facilities

Nakagawa, Takahiro; Takada, Chie; Tsujimura, Norio

Radiation Protection Dosimetry, 146(1-3), p.140 - 143, 2011/07

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

Radiation workers engaging in the fabrication of MOX fuels are exposed to neutrons, and hence thermoluminescent albedo dosemeters (TLAD) need to be used at JAEA-NCL. Because estimating the doses using TLADs are susceptible to the neutron energy spectrum, the authors have issued TLADs incorporating Solid-State Nuclear Tracks Detectors (SSNTDs) to selected workers who are routinely exposed to neutrons and been analyzing the relationship between the SSNTD and the TLAD (T/Rf) over the past 6 years. Consequently, the $$T$$/$$R$$$$_{rm f}$$ in each year was 10-20 (3.363 mm$$^{-2}$$)/(mSv $$^{137}$$Cs eq.), which is smaller than the data during 1991-1993, although the neutron spectra had not changed compared with that of the early 1990s. This decrease of the $$T$$/$$R$$$$_{rm f}$$ implies that the ratio of work carried out nearby the gloveboxes to total work decreased.

Journal Articles

Management of cosmic radiation exposure for aircraft crew in Japan

Yasuda, Hiroshi*; Sato, Tatsuhiko; Yonehara, Hidenori*; Kosako, Toshiso*; Fujitaka, Kazunobu*; Sasaki, Yasuhito*

Radiation Protection Dosimetry, 146(1-3), p.123 - 125, 2011/07

 Times Cited Count:13 Percentile:71.79(Environmental Sciences)

The National Institute of Radiological Sciences (NIRS) has helped the airlines companies to follow the guideline, particularly for the calculation of aviation route doses. The presentation will show the annual individual doses of aircraft crew calculated for the 2007 fiscal year.

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:11.72(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:1 Percentile:11.72(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

Dose evaluation from multiple detector outputs using convex optimisation

Hashimoto, Makoto; Iimoto, Takeshi*; Kosako, Toshiso*

Radiation Protection Dosimetry, 146(1-3), p.65 - 68, 2011/07

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

A dose evaluation using multiple radiation detector outputs can be improved by the convex optimisation. It enables flexible dose evaluation corresponding to the radiation field. The neutron ambient dose equivalent is evaluated using a mixed-gas proportional counter. The reliability of evaluated dose values are comparable with current dosimeter. An application to neutron individual dose equivalent measurement is also investigated. The combination of dosimeters with high orthogonality of response characteristics tends to show good suitability for dose evaluation.

Journal Articles

Computer simulations for internal dosimetry using voxel models

Kinase, Sakae; Mohammadi, A.; Takahashi, Masa; Saito, Kimiaki; Zankl, M.*; Kramer, R.*

Radiation Protection Dosimetry, 146(1-3), p.191 - 194, 2011/07

 Times Cited Count:4 Percentile:36.36(Environmental Sciences)

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:4 Percentile:36.36(Environmental Sciences)

Journal Articles

The Investigation and consideration for introduction of surface contamination evaluation method based on JIS

Usui, Toshihide; Takashima, Hideki; Iwasa, Atsutoshi; Hamazaki, Masaaki

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

Journal Articles

Monitoring network of atmospheric Radon-222 concentration in East Asia and backward trajectory analysis of Radon-222 concentration trend at a small solitary island on Pacific Ocean

Okura, Takehisa; Yamazawa, Hiromi*; Moriizumi, Jun*; Hirao, Shigekazu*; Guo, Q.*; Tojima, Yasunori*; Iida, Takao*

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

Monitoring network of $$^{222}$$Rn concentration in air which was measured in Beijing, Nagoya, Hegura-jima, Hachijo-jima and Hateruma-jima, as a tracer for long-range transport in East Asia was established. At inland sites, Beijing and Nagoya, high concentrations $$^{222}$$Rn were measured, at marine sites, Hachijo-jima and Hateruma-jima, $$^{222}$$Rn concentrations level was very low. Seasonal variations of the $$^{222}$$Rn concentration show that $$^{222}$$Rn concentration was the lowest in the summer and the highest in the winter. Diurnal variations were measured at inland sites. At marine sites several-day-cycle variations were measured. It was pointed out by this study that the several-day-cycle variations at Hachijo-jima were dependent on synoptic-scale atmospheric disturbance. Backward trajectory analysis of the relationship between atmospheric $$^{222}$$Rn concentrations at Hachijo-jima and transport pathway of air mass indicates that atmospheric $$^{222}$$Rn at Hachijo-jima has much to do with transport pathway of air.

Journal Articles

Development of a hand-held fast neutron survey meter

Yoshida, Tadayoshi; Tsujimura, Norio; Yamano, Toshiya*

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

A neutron survey meter with a ZnS(Ag) scintillator to measure recoil protons was built. The detection probe weighs approx. 2 kg, therefore providing us with true portability. Performance tests exhibited satisfactory neutron dosimetry characteristics at unmoderated or lightly moderated fission neutron fields and in particular work environments at a MOX fuel facility. This new survey meter will augment a routine neutron monitoring inconveniently being carried out by moderator-based neutron survey meters.

Journal Articles

Prediction analysis of dose equivalent responses of neutron dosemeters used at a MOX fuel facility

Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

To predict how accurately the neutron dosemeters can measure the neutron dose equivalent (rate) in MOX fuel fabrication facility work environments, the calculations of the dose equivalent responses of neutron dosemeters were performed by the spectral folding method. The dosemeters selected included two types of personal dosemeters (a thermoluminescent albedo neutron dosemeter and an electronic neutron dosemeter), three moderator-based neutron survey meters and one special instrument called an $$H$$$$_{rm p}$$(10) monitor. The calculations revealed the energy dependences of the responses expected within the entire range of neutron spectral variation observed in neutron fields at workplaces.

Journal Articles

Development of calculation code for estimating radiation dose for hypothetical accident of nuclear facility considering radioactive decay chain during atmospheric dispersion of released radionuclides

Takeyasu, Masanori; Nakano, Masanao; Sumiya, Shuichi; Nemoto, Hiromi*; Kanno, Mitsuhiro*; Kurosawa, Naohiro*

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 4 Pages, 2010/05

The dose to the public at hypothetical accident of nuclear facility is estimated on the basis of the method described in the Japanese meteorological guideline. However, the radioactive decay during atmospheric dispersion of released radionuclide is not considered in the calculation formula in the guideline. Therefore, when the radionuclide of the half life such as a few min is released, the dose may be excessively over-estimated. In this study, the calculation code was developed which could consider the radioactive decay of the released radionuclide and the generation of the product. The dose calculated on the basis of the developed code was compared with that on the basis of the guideline.

Journal Articles

Equations for estimating chest wall thickness in lung counting at JAEA-NCL

Kanai, Katsuta; Kurihara, Osamu

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

Chest wall thickness (CWT) of the subject is an important modifier to determine the lung burden of inhaled actinides such as Pu isotopes or $$^{241}$$Am through lung counting. CWT prediction equations as a function of biometric indexes have been proposed by many authors based on chest wall measurements made with an ultrasound device. In the present study we derived such equations from CWT data of our subjects and then evaluated their applicability to monitoring with our currently used lung counter, mainly examining the accuracy of determinations of $$^{241}$$Am, useful as a unique indicator that can be detected in most cases of internal contamination with Pu compounds. The error of the equations obtained was found to be within the range of - 8 mm to + 6 mm against actual CWT values of our subjects, complying with the bias performance criteria for direct measurements. However, further studies might be needed to clarify the effect of the difference in posture on the CWT caused by the modification of the counting geometry made for our lung counter.

Journal Articles

Effect of density on absorbed doses in a mouse voxel phantom

Mohammadi, A.; Kinase, Sakae

Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05

Oral presentation

Comparison of calibration factors for dosemeters at $$^{241}$$Am-Be neutron standard fields using new and old sources

Kowatari, Munehiko; Tatebe, Yosuke; Sato, Yasuo; Kawasaki, Katsuya; Yoshizawa, Michio

no journal, , 

For the contribution to the effective operation of $$^{241}$$Am-Be neutron standard fields, experimental studies on the comparison of the calibration factors for neutron dosemeters by old and new sources were made. Measured calibration factors for each dosemeter were compared by estimating their E$$_{n}$$ values. Results of the variation of calibration factor for neutron dosemeters were quite satisfactory and identical calibration factors were obtained at neutron calibration fields by new and old $$^{241}$$Am-Be source.

Oral presentation

Radiation protection guidelines for releasing commodities from radiation controlled areas

Yamamoto, Hideaki

no journal, , 

The Japanese radiation protection criteria for releasing commodities from radiation controlled areas are set in terms of the radioactive contamination concentrations on the surface of the commodities. The current criteria were established more than 40 years ago, based on the knowledge of radiological protection of those days. The Japanese Standardization Committee on Radiation Protection, Japan Health Physics Society has been making some fact-finding studies on the control practices for releasing commodities from radiation controlled areas in some typical nuclear sites. Based on the results from these studies the Committee will develop a new approach to a possible amendment of the release criteria. The current principles of radiological protection suggest that an application of the concept of "clearance of materials from regulatory control" may establish a logical and practical framework for radiological protection for releasing commodities from radiation controlled areas.

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