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Hakoda, Teruyuki; Kojima, Takuji
Radiation Physics and Chemistry, 74(5), p.302 - 309, 2005/12
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)no abstracts in English
-ray dose components in criticality accident situationsSono, Hiroki; Yanagisawa, Hiroshi*; Ono, Akio*; Kojima, Takuji; Soramasu, Noboru*
Journal of Nuclear Science and Technology, 42(8), p.678 - 687, 2005/08
Times Cited Count：4 Percentile：30.44(Nuclear Science & Technology)Component analysis of -ray doses in criticality accident situations is indispensable for further understanding on emission behavior of -rays and accurate evaluation of external exposure to human bodies. Such dose components were evaluated, categorizing -rays into four components: prompt, delayed, pseudo components in the period of criticality, and a residual component in the period after the termination of criticality. This evaluation was performed by the combination of dosimetry experiments at the TRACY facility using a thermoluminescent dosimeter (TLD) made of lithium tetra borate and computational analyses using a Monte Carlo code. The evaluation confirmed that the dose proportions of the above components varied with the distance from the TRACY core tank. This variation was due to the difference in attenuation of the individual components with the distance from the core tank. The evaluated dose proportions quantitatively clarified the contribution of the pseudo and the residual components to be excluded for accurate evaluation of -ray exposure.
Shibata, Yasushi*; Yamamoto, Kazuyoshi; Matsumura, Akira*; Yamamoto, Tetsuya*; Hori, Naohiko; Kishi, Toshiaki; Kumada, Hiroaki; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Nakai, Kei*; et al.
JAERI-Research 2005-009, 41 Pages, 2005/03
JAERI-Research-2005-009.pdf:1.99MB
The measurement of neutron flux and boron concentration in the blood during medical irradiation is indispensable in order to evaluate the radiation in boron neutron capture therapy. It is, however, difficult to measure the blood boron concentration during neutron irradiation because access to the patient is limited. Therefore we prospectively investigated the predictability of blood boron concentrations using the data obtained at the first craniotomy after infusion of a low dosage of BSH. When the test could not be carried out, the blood boron concentration during irradiation was also predicted by using the 2-compartment model. If the final boron concentration after the end of the infusion is within 95% confidence interval of the prediction, direct prediction from biexponential fit will reduce the error of blood boron concentrations during irradiation to around 6%. If the final boron concentration at 6 or 9 hours after the end of infusion is out of 95% confidence interval of the prediction, proportional adjustment will reduce error and expected error after adjustment to around 12%.
Solomon, H. M.*; Kojima, Takuji
Nucleus, 33, p.16 - 20, 2005/00
Low-dose dosimeters were developed based on the mixture films of polyvinyl butyral (PVB) and the acid-sensitive dye leucomalachite green (LMG). Chloral hydrate (RX) was added to the mixture for enhancement of the radiation sensitivity of the film dosimeters. Different film dosimeter materials were prepared using 9.07 
10
mole LMG per one gram PVB with various RX:LMG molar concentration ratio. The dosimeter response, which is expressed in terms of change in absorbance at 628 nm per unit thickness, increased linearly with dose and RX concentration. The PVB-LMG dosimeter system, in which the ratio of RX concentration to that of LMG is higher than 10, show measurable dose range of 1-100 Gy for 
Co -rays.
Nakamura, Takemi*; Tonoike, Kotaro; Miyoshi, Yoshinori
Radiation Protection Dosimetry, 110(1-4), p.483 - 486, 2004/09
Times Cited Count：2 Percentile：17.16(Environmental Sciences)Dose measurement and evaluation technique in criticality accident conditions with a thermo luminescence dosimeter (TLD) was studied at the Transient Experiment Critical Facility (TRACY) of Japan Atomic Energy Research Institute (JAERI). The tissue absorbed dose can be derived from the ambient dose equivalent given by measurement with a TLD using the conversion factor given by computation. Using this technique, the neutron dose around the SILENE reactor of the Institute for Radioprotection and Nuclear Safety (IRSN) of France was measured in the Accident Dosimetry Intercomparison Exercise (June 10-21, 2002) organized by OECD/NEA and IRSN. In this exercise, the dose was also measured with a TLD. In this report, measurements and evaluation results at TRACY and SILENE are presented.
Mai, H. H.*; Duong, N. D.*; Kojima, Takuji
Radiation Physics and Chemistry, 69(5), p.439 - 444, 2004/04
Times Cited Count：21 Percentile：77.76(Chemistry, Physical)Characteristics of the polyvinyl chloride films containing 0.11wt% of malachite green oxalate or 6GX-setoglausine with 100
m in thickness were studied for use as routine dosimeters in radiation processing. These films show basically color bleaching under Co -ray irradiation in a dose range of 5 to 50 kGy. The sensitivity of the dosimeters and the linearity of dose response curves are improved by adding 2.5% of chloral hydrate [CCl
CH(OH)
] and 0.15% hydroquinone [HOC
H
OH]. These additions extent the minimum dose limit to 1 kGy covering dosimetric quality assurance in radiation processing of food and healthcare products. The dose responses of both films at irradiation temperatures of 20-35
C are constant relative to those at 25C, and the irradiation temperature coefficients for 35-55C were estimated to be (0.43 
0.01)%/ C. The dosimeter characteristics are stable within 1% at 25C before and 60 days after irradiation.
ray dose rate in nuclear fusion reactorSato, Satoshi; Kawasaki, Nobuo*; Kume, Etsuo; Nishitani, Takeo
Journal of Nuclear Science and Technology, 41(Suppl.4), p.62 - 65, 2004/03
no abstracts in English
Mehta, K.*; Kojima, Takuji; Sunaga, Hiromi
Radiation Physics and Chemistry, 68(6), p.959 - 962, 2003/12
Times Cited Count：3 Percentile：25.75(Chemistry, Physical)Applicability of the existing dosimetry systems to high-power Bremsstrahlung irradiation was investigated through a dose intercomparison study, where several dosimeters were irradiated in the dose range 4-12 kGy in identical polyethylene phantoms in a Bremsstrahlung beam obtained from a 5-MeV electron accelerator. Included in the study were alanine dosimeters molded by three different binders, three types of liquid dosimeters:ceric-cerous, dichromate and ethanol-chlorobenzen (ECB), and glutamine powder. The dosimeter responses for Bremsstrahlung radiation were analyzed at the issuing laboratories, and the dose values determined using calibration based on cobalt-60 -ray irradiation. Dose values for all the three dose levels for all dosimetry systems were in good agreement of better than 3%. The results of the study demonstrate that these existing dosimetry systems have a potential for application to high-power Bremsstrahlung irradiation.
Endo, Akira; Yamaguchi, Yasuhiro
Radiation Research, 159(4), p.535 - 542, 2003/04
Times Cited Count：14 Percentile：39.81(Biology)The first criticality accident in Japan occurred in a uranium processing plant in Tokai-mura in September, 1999. In this accident, two workers on the site were heterogeneously exposed to neutrons and rays produced by the nuclear fission. Heterogeneous exposure influenced the clinical course observed in the skin and organs of these workers. By request from medical groups, we attempted to clarify the dose distribution of the two heavily exposed workers with the aid of computer simulation, which is currently the only means by which to address this complicated problem. This paper presents elucidated skin dose distributions, depth dose distributions inside the trunk, and neutron-to- dose ratios.
Takahashi, Fumiaki; Endo, Akira; Yamaguchi, Yasuhiro
Radiation Protection Dosimetry, 106(3), p.197 - 206, 2003/00
Times Cited Count：4 Percentile：31.59(Environmental Sciences)Some data were derived using recent sophisticated methods to convert rapidly specific activity of induced sodium-24 to average dose over a whole body in criticality accidents. Monte Carlo calculations using the MCNP-4B code were performed to study energy spectra of neutrons and gamma rays for some criticality systems with fissile uranium. Absorbed dose to human body and activation of sodium were also analysed against external radiation by simulations using a phantom. It was found that neutron dose assessment from induced 
Na would be important to give an initial guidance of a treatment. The condition of neutron exposure, however, did not influence the quantitative relation dose by gamma rays induced within a body and activity of Na. Analyses were made to clarify the dependence of conversion from Na specific activity to dose on the orientation and the size of human body. This study suggested that the size of uranium solution and material around the fuel should be informed to properly estimate dose against external photons from neutron dose.
Sakamoto, Yukio
JAERI-Research 2002-025, 34 Pages, 2002/11
JAERI-Research-2002-025.pdf:1.91MB
no abstracts in English
-ray dose rates around the duct penetration by three-dimensional Monte Carlo decay -ray transport calculation with variance reduction methodSato, Satoshi; Iida, Hiromasa; Nishitani, Takeo
Journal of Nuclear Science and Technology, 39(11), p.1237 - 1246, 2002/11
Times Cited Count：27 Percentile：83.19(Nuclear Science & Technology)no abstracts in English
Takada, Eiji*; Fujimoto, Nozomu; Nojiri, Naoki; Umeta, Masayuki; Kokusen, Shigeru; Ashikagaya, Yoshinobu
JAERI-Data/Code 2002-009, 83 Pages, 2002/05
JAERI-Data-Code-2002-009.pdf:3.51MB
Dose equivalent rate around the fuel handling machine, the control rod handling machine, stand pipe compartment, maintenance pit were measured during gamma ray measurements from HTTR fuel, which was called as “power distribution measurements". The power distribution measurement was the first time to handle the fuel blocks irradiated in the core. Dose equivalent rate measurement aiming the check of shielding performance of components, the check of unexpected streaming path. The radiation monitoring during operation was carried out. As the results, there was no problem on shielding. The measured data at operation condition were also obtained. The data will be useful to expect operation circumstance in the future.
Tanaka, Shunichi
Journal of Radiation Research, 42(Suppl.), p.S1 - S9, 2002/00
A criticality accident occured on September 30,1999, in a conversion facity at the JCO tokai site. The accident continued for about 19 hours before the criticality could be stopped, during which time neutrons and gamma-rays were emitted continuously due to fission reactions. The total number of fission reactions was 2.5x10
. The accident gave radiation dose to 3 employees and fatal dose to 2 of them. The individual dose was estimated for 234 resident, 169 JCO employees and 260 emergency personnel, of which the maximum dose was 48 mSv.
Endo, Akira; Yamaguchi, Yasuhiro; Sakamoto, Yukio; Yoshizawa, Michio; Tsuda, Shuichi
Radiation Protection Dosimetry, 93(3), p.207 - 214, 2001/00
Times Cited Count：6 Percentile：44.06(Environmental Sciences)no abstracts in English
Shibata, Keiichiro*; Maki, Koichi*; Inoue, Takashi*; Hanada, Masaya; Okumura, Yoshikazu; Yamashita, Y.*
Fusion Engineering and Design, 51-52, p.357 - 362, 2000/11
Times Cited Count：1 Percentile：12.08(Nuclear Science & Technology)no abstracts in English
Co -ray calibration laboratory for radiation processingTachibana, Hiroyuki; Kojima, Takuji; ; ; Yotsumoto, Keiichi; Tanaka, Ryuichi
Radioisotopes, 48(4), p.247 - 256, 1999/04
no abstracts in English
Co -ray dosimetry at JAERI involving a two-way dose intercomparison study with NPL in the dose range 1-50kGyKojima, Takuji; Tachibana, Hiroyuki; ; *; P.H.G.Sharpe*
Radiation Physics and Chemistry, 54(6), p.619 - 626, 1999/00
Times Cited Count：10 Percentile：60.61(Chemistry, Physical)no abstracts in English
Kojima, Takuji; ; ; Tachibana, Hiroyuki; Tanaka, Ryuichi
Applied Radiation and Isotopes, 43(10), p.1197 - 1202, 1992/00
no abstracts in English
; ; Morita, Yosuke; Seguchi, Tadao
Appl.Radiat.Isot., 37(6), p.517 - 520, 1986/00
no abstracts in English
-ray Measurement; ;
JAERI-M 84-003, 30 Pages, 1984/02
no abstracts in English
