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Journal Articles

Estimating internal dose coefficients of short-lived radionuclides in accordance with ICRP 2007 Recommendations

Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki

Journal of Nuclear Science and Technology, 56(5), p.385 - 393, 2019/05

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

At high energy accelerator facilities, various radionuclides are produced by nuclear reactions of high energy particles with structure and/or ambient air of the facilities. Consequently, the radionuclides are potential sources of internal exposure for works of the facilities. However, the International Commission on Radiological Protection (ICRP) do not provide dose coefficients, which are committed effective doses per intake, for the short-lived radionuclides whose half-lives are shorter than 10 minutes in accordance with the ICRP 2007 Recommendations. Then, we estimated the dose coefficients for inhalation and ingestion of these short-lived radionuclides in accordance with the ICRP 2007 Recommendations. In addition, we compared the dose coefficients with those in accordance with the ICRP 1990 Recommendations. As a result, a decreasing tendency was shown in the dose coefficients for inhalation cases; an increasing tendency was observed in those for ingestion cases. It was found that these changes in dose coefficients were mainly caused by the revision of the dose calculation procedures, alimentary tract models. The result of this study will be useful for planning of radiation protection at the high energy facilities.

Journal Articles

Variation of half-life and internal-conversion electron energy spectrum between $$^{235m}$$U oxide and fluoride

Shigekawa, Yudai*; Kasamatsu, Yoshitaka*; Yasuda, Yuki*; Kaneko, Masashi; Watanabe, Masayuki; Shinohara, Atsushi*

Physical Review C, 98(1), p.014306_1 - 014306_5, 2018/07

 Times Cited Count:1 Percentile:63.43(Physics, Nuclear)

The nuclear half-life of $$^{235m}$$U has been reported to vary depending on the chemical environment. In this study, both the half-life and the internal-conversion (IC) electron energy spectrum were measured for $$^{235m}$$U with identical chemical environments for the first time. $$^{235m}$$U oxide and fluoride samples were subjected to these measurements, and clear differences in the half-life and the energy spectrum between these samples were observed. The peaks in the energy spectra were identified with the relativistic density functional theory calculation, and the molecular orbital states of the $$^{235m}$$U oxide and fluoride estimated from the energy spectra and the calculation qualitatively explained the difference in the half-lives between the samples.

Journal Articles

Long-term predictions of ambient dose equivalent rates after the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Takahashi, Tomoyuki*; Saito, Kimiaki

Journal of Nuclear Science and Technology, 54(12), p.1345 - 1354, 2017/12

 Times Cited Count:5 Percentile:18.65(Nuclear Science & Technology)

Journal Articles

Analysis of ambient-dose-rate trends in Fukushima; Ecological half-life, effect of snow covering

Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru

Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.

JAEA Reports

Technological study about a disposal measures of low-level radioactive waste including uranium and long-half-life radionuclides

Sugaya, Toshikatsu; Nakatani, Takayoshi; Sasaki, Toshihisa*; Nakamura, Yasuo*; Sakai, Akihiro; Sakamoto, Yoshiaki

JAEA-Technology 2016-036, 126 Pages, 2017/02

JAEA-Technology-2016-036.pdf:7.28MB

At the Radioactive Waste Management and Disposal Project Department Sector of Decommissioning and Radioactive Waste Management, we performed the technological study about the disposal measures of the low-level radioactive waste targeted for uranium-bearing waste and intermediate depth disposal-based waste occurring from the process of the nuclear fuel cycle.

Journal Articles

Prediction of ambient dose equivalent rates for 30 years after the Fukushima accident and its technological development

Kinase, Sakae

Nippon Genshiryoku Gakkai-Shi, 58(6), p.362 - 366, 2016/06

no abstracts in English

Journal Articles

Changes in ambient dose equivalent rates around roads at Kawamata town after the Fukushima accident

Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi*; Yamamoto, Hideaki; Saito, Kimiaki

Radiation Protection Dosimetry, 167(1-3), p.340 - 343, 2015/11

 Times Cited Count:3 Percentile:57.24(Environmental Sciences)

Journal Articles

Prediction of ambient dose equivalent rates for the next 30 years after the accident

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi*; Yamamoto, Hideaki; Saito, Kimiaki

Proceedings of International Symposium on Radiological Issues for Fukushima's Revitalized Future, p.40 - 43, 2015/00

To support recovery and rehabilitation in Fukushima, prediction models have been developed for ambient dose equivalent rate distribution within the 80 km-radius around the Fukushima Daiichi Nuclear Power Plant. The prediction models that are based on bi-exponential functions characterized by ecological half-lives of radioactive caesium for land-use, enable Fukushima residents to obtain distribution maps of ambient dose equivalent rates for the next 30 years after the accident. Model parameters were evaluated using ambient dose equivalent rates through car-borne surveys. The model parameters in deciduous and evergreen forest areas were found to be different from those in other areas. In addition, it was found that distribution maps of ambient dose equivalent rates for the next 30 years after the accident, created by the prediction models would be useful for follow-up of the radiological situation.

Journal Articles

Research and development activities for accelerator driven system at JAERI

Tsujimoto, Kazufumi; Sasa, Toshinobu; Nishihara, Kenji; Oigawa, Hiroyuki; Takano, Hideki*

Proceedings of International Conference on Physics of Fuel Cycles and Advanced Nuclear Systems; Global Developments (PHYSOR 2004) (CD-ROM), 8 Pages, 2004/04

The Japan Atomic Energy Research Institute (JAERI) is developing an Accelerator Driven System (ADS) for transmutation of nuclear waste such as minor actinide (MA) and long-lived fission product (LLFP). To study and evaluate the feasibility of ADS by physical and engineering viewpoints, the Transmutation Experimental Facility (TEF) is proposed under a framework of J-PARC (Japan Proton Accelerator Research Complex) project. The TEF consists of two facilities named as Transmutation Physics Experimental Facility (TEF-P) and ADS Target Test Facility (TEF-T). The TEF-P consists of a zero-power critical assembly which is operated with a low power proton beam to research the reactor physics and the controllability of ADS. The TEF-T is a facility for material irradiation and partial mockup of beam window which can accept a maximum 600MeV-200kW proton beam into the Pb-Bi eutectic target. The purposes, experimental items and the specifications of the facilities are described.

JAEA Reports

Basic study on ultra high sensitive neutron dosimetry technique based on resonant laser ablation, JAERI's nuclear research promotion program, H12-035 (Contract Research)

Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Uritani, Akira*; Enokida, Yoichi*; Watanabe, Kazuo

JAERI-Tech 2004-010, 62 Pages, 2004/03

JAERI-Tech-2004-010.pdf:2.6MB

no abstracts in English

Journal Articles

Half-life of $$^{228}$$Pu and $$alpha$$-decay energy of $$^{228}$$Np

Nishio, Katsuhisa; Ikezoe, Hiroshi; Mitsuoka, Shinichi; Sato, Kenichiro; Lin, C. J.

Physical Review C, 68(6), p.064305_1 - 064305_6, 2003/12

 Times Cited Count:17 Percentile:26.87(Physics, Nuclear)

We observed two $$alpha$$-decay chains starting from $$^{228}$$Pu in the reaction of $$^{34}$$S+$$^{198}$$Pt, and the half-life was measured to be 1.1$$^{+2.6}_{-0.5}$$ s for the first time. This contradicts the literature value of 4 ms as an upper limit, although the $$alpha$$-decay energy agrees with each other. The present half-life follows the Geiger-Nuttall curve for even-even Pu isotopes, showing the dominant $$alpha$$-decay branch. In this reaction, six $$alpha$$ decays of $$^{228}$$Np were firstly observed. The average $$alpha$$-particle energy was 7097$$pm$$61 keV. The evaporation residue cross sections of $$^{228}$$Pu, $$^{228}$$Np and $$^{225}$$U are reproduced by a statistical model calculation.

Journal Articles

Depth profiles of long lived radionuclides in Chernobyl soils sampled around 10 years after the accident

Amano, Hikaru; Onuma, Yoshikazu*

Journal of Radioanalytical and Nuclear Chemistry, 255(1), p.217 - 222, 2003/01

 Times Cited Count:7 Percentile:54.12(Chemistry, Analytical)

no abstracts in English

Journal Articles

Systematics of cluster decay modes

Poenaru, D. N.; Nagame, Yuichiro; Gherghescu, R. A.*; Greiner, W.*

Physical Review C, 65(5), p.054308_1 - 054308_6, 2002/05

 Times Cited Count:75 Percentile:4.81(Physics, Nuclear)

no abstracts in English

JAEA Reports

Improvement of the technique for stack monitoring based on behavior analysis of natural radio-nuclides; The technique for reducing the value of the exhaust monitor's background

Izaki, Kenji; Noda, Kimio; ; Kashimuta, Yoshio*

JNC-TN8410 2001-005, 30 Pages, 2001/01

JNC-TN8410-2001-005.pdf:0.62MB

Stack monitoring is the most important work in radiation control works. Exhaust monitors used for stack monitoring have the background (which is the counts by natural radio-nuclides) on normal condition, and the values of the background vary with the facilities. Therefore, if the value of background is high, it is difficult to estimate rapidly the radioactive concentration in the exhaust. In order to estimate rapidly the radioactive concentration in exhaust, we analyzed the behavior of natural radioactivity in the facilities and examine the technique fo reducing the value of the background. As a result of the examination, we found that it is possible to estimate rapidly if we change over the monitoring point to immediately after the HEPA filters on the exhaust duct. In this reports, the analyzed results of behavior of natural radio-nuclides in the facilities and the technique for reducing the values of the background are described. To reduce the value of the background has a major effect on not only rapidly estimating the radioactive density in the exhaust but also finding the unusual things on stack monitoring.

JAEA Reports

None

; *; *

JNC-TN8200 2001-001, 42 Pages, 2001/01

JNC-TN8200-2001-001.pdf:3.16MB

None

Journal Articles

Decay studies of neutron-rich isotopes produced in proton-induced fission of actinides

Ichikawa, Shinichi; Asai, Masato*; Tsukada, Kazuaki; Nishinaka, Ichiro; Nagame, Yuichiro; Osa, Akihiko; Shibata, Michihiro*; Kawade, Kiyoshi*; Kojima, Yasuaki*; Sakama, Minoru*; et al.

Proceedings of 2nd International Conference on Fission and Neutron-rich Nuclei, p.203 - 205, 2000/03

no abstracts in English

JAEA Reports

Influence of naturally-occurring heterogeneous complex-forming materials on the migration behavior of actinides in the geosphere (III)

Tochiyama, Osamu*

JNC-TJ8400 2000-044, 53 Pages, 2000/02

JNC-TJ8400-2000-044.pdf:1.41MB

To estimate the polyelectrolyte effect and the effect of the heterogeneous composition of humic acids, the complex formation constants of Eu(III) and Ca(II) with Aldrich humic acid and polyacrylic acid were obtained, for Eu(10$$^{-8}$$ to 10$$^{-5}$$ M) by solvent extraction with TTA and TBP in xylene, for Ca (10$$^{-10}$$M) with TTA and TOPO in cyclohexane and for Ca(10$$^{-4}$$M) by using ion-selective electrode. By defining the apparent formation as $$beta_{alpha}$$ = [MR$$_{m}$$]/([M][R]), where [R] denotes the concentration of dissociated functional group, [M] and [MR$$_{m}$$] denote the concentration of free and bound metal ion and pcH is defined as-log[H], the values of log$$beta_{alpha}$$ have been obtained at pcH 4.8 - 5.5 in 0.1 - 1.0M NaClO$$_{4}$$ and NaCl. Log$$beta_{alpha}$$ of Eu-humate varied from 5.0 to 9.3 and that of Ca-humate from 2.0 to 3.4..For both humate and polyacrylate, log$$beta_{alpha}$$ increased with pcH or with the degree of dissociation. The increase in the ionic strength O.1 to 1.0 M decreased the log$$beta_{alpha}$$, the decrease in log$$beta_{alpha}$$ of Eu(III)-humate is 1.6, that of Eu(III), polyacrylate 0.7, that of Ca(II)-humate 1.9 and that of Ca(II)-polyacrylate 1.2. While the increase in the metal ion produced no effect on log$$beta_{alpha}$$ of polyacrylate, log$$beta_{alpha}$$ of humate decreased. Depending on the concentration of Eu(III), the coexistence of Ca(II) reduced log $$beta_{alpha}$$ of humate by 0 to 0.8. The dependence of log$$beta_{alpha}$$ of humate on the metal ion concentration suggests the coexistence of strong and weak binding sites in the hmnic acid.

Journal Articles

Superheavy elements; Synthesis of new elements 114, 116 and 118

Nishinaka, Ichiro

Kagaku To Kogyo, 53(5), P. 607, 2000/00

no abstracts in English

Journal Articles

Transfer of long lived radionuclides in Chernobyl soils to edible plants

Amano, Hikaru; Ueno, Takashi; Arkhipov, N.*; Paskevich, S.*; Onuma, Yoshikazu*

Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 6 Pages, 2000/00

no abstracts in English

Journal Articles

$$beta$$-decay half-lives of new neutron-rich isotopes of elements from Pm to Tb

Ichikawa, Shinichi; Asai, Masato*; Tsukada, Kazuaki; Osa, Akihiko; Sakama, Minoru*; Kojima, Yasuaki*; Shibata, M.*; Nishinaka, Ichiro; Nagame, Yuichiro; Oura, Yasutsugu*; et al.

AIP Conference Proceedings 495, p.103 - 106, 1999/12

no abstracts in English

95 (Records 1-20 displayed on this page)