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Journal Articles

LaCl $_{3}$ (Ce) scintillation detector applications for environmental -ray measurements of low to high dose rates

Tsutsumi, Masahiro; Tanimura, Yoshihiko

Nuclear Instruments and Methods in Physics Research A, 557(2), p.554 - 560, 2006/02

https://doi.org/10.1016/j.nima.2005.11.117

Times Cited Count：14 Percentile：68.12(Instruments & Instrumentation)

A new cerium-doped LaCl $_{3}$ (Ce) scintillator is evaluated with respect to the application in environmental -ray dosimetry and spectrometry. The scintillator is very attractive for -ray spectrometry in the case of high count rate, because it has excellent energy resolution and fast decay time. The performance characteristics of a scintillator with a 25.4 mm 25.4 mm LaCl $_{3}$ (Ce) crystal are studied and compared to those of a NaI(Tl) scintillator with the same size crystal. Acquired pulse-height spectra are converted to dose rates by using the G(E) function method. Though the LaCl $_{3}$ (Ce) crystal itself produces a rather high background in the crystal itself, the scintillator provides good energy information and dose-rate readings from low to high-level (several mGy/h) by subtracting the self-background. The properties of LaCl $_{3}$ (Ce) scintillator suggest that the scintillator could be a promising candidate for monitoring at high-dose levels as in emergencies, as well as at ordinary levels of background radiation.

Journal Articles

Time-dependence of differential G-values of OH radicals in water under Ne ion radiolysis

Taguchi, Mitsumasa; Kojima, Takuji

JAEA-Review 2005-001, TIARA Annual Report 2004, p.181 - 182, 2006/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2005-001-p0127-p0267.pdf

The yields of OH radicals in water containing phenol have been investigated for several ten MeV/n C ion and Ne ion having the same LET value, as a function of the residual ion energy at the specific depth in water. In this study, beside such energy dependence, the dependence of reaction time of OH radical yield was examined by changing the concentration of phenol as solute. The defferential G'-values of OH radicals, those G-values per kinetic energy of ions increase with specific energy of Ne ions. The G'-value just after irradiation(1.5ns) is relatively high but become lower with reaction time to be the value (2.7) obtained for $^{60}$ Co -rays. It suggests the diffusion behavior of OH radicals locally induced in water.

Journal Articles

Decomposition of -nonylphenols in water and elimination of their estrogen activities by $^{60}$ Co -ray irradiation

Kimura, Atsushi; Taguchi, Mitsumasa; Otani, Yoshimi*; Takigami, Machiko; Shimada, Yoshitaka*; Kojima, Takuji; Hiratsuka, Hiroshi*; Namba, Hideki

Radiation Physics and Chemistry, 75(1), p.61 - 69, 2006/01

https://doi.org/10.1016/j.radphyschem.2005.05.016

Times Cited Count：13 Percentile：65.83(Chemistry, Physical)

Decomposition of -Nonylphenols (NPs) in water at 1 mol dm $^{-3}$ was decreased exponentially with absorbed dose when NPs were irradiated by $^{60}$ Co-rays. Two products having molecular weight of 236, presumably OH adducts of NPs, were detected by LC-MS analyses. The elimination of estrogen activity of aqueous NPs solution including such irradiation products at 5000 Gy (J kg $^{-1}$ ) was confirmed by the yeast two hybrid assay. These results should expand the application of ionizing radiation to the treatment of NPs.

JAEA Reports

Estimation methods of blood boron concentration and error evaluation during boron neutron capture therapy for malignant brain tumor

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%.

Journal Articles

Development of PVB film for low-dose dosimetry in radiation processing

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 $^{-5}$ 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 $^{60}$ Co -rays.

JAEA Reports

Development of elemental components in NDA systems for certifying radioactive wastes with the clearance level

Tsutsumi, Masahiro; Oishi, Tetsuya*; Yamasoto, Kotaro; Yoshida, Makoto

JAERI-Research 2004-021, 43 Pages, 2004/12

JAERI-Research-2004-021.pdf:8.55MB

We have designed and developed a measurement system to certify radioactive wastes below the clearance level. By advancing non-destructive -ray assay technology, it aims at quantitative determination of radionuclides contained in 200 litter drum/container wastes. Unlike the waste from a nuclear power plant, you have to assume that the waste originating from radioisotope usage and nuclear research laboratory have a variety of contents and a complex mixture of radionuclides, and furthermore the uniformity of activity concentration is unknown. To cope with the problems, we have developed the -ray measuring instruments (units) with effective improvement of capability against each problem. They are (1) germanium spectrometry unit for enhanced peak identification, (2) positioning detection unit for positioning of interactions and (3)high-efficiency detection unit for separation of low-energy component. This report summarizes the direction of the clearance level measuring system and the three developed measuring units with their performances.

Journal Articles

Discrimination of neutrons and ray by a neutron detector comprising a superconducting tunnel junction on a single crystal of Li $_{2}$ B $_{4}$ O $_{7}$

Nakamura, Tatsuya; Katagiri, Masaki; Soyama, Kazuhiko; Ukibe, Masahiro*; Ikeuchi, Takashi*; Okubo, Masataka*

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.402 - 404, 2004/08

https://doi.org/10.1016/j.nima.2004.05.020

Times Cited Count：8 Percentile：48.81(Instruments & Instrumentation)

We evaluated the neutron--rays discrimination of the neutron detector comprising a superconducting tunnel junction (STJ) on the single crystal of Li $_{2}$ B $_{4}$ O $_{7}$ . The neutron detector was irradiated with X-rays, -rays and neutrons, and the signal pulses were analyzed including pulse height distributions and rise times. It was found that the most of the signal pulses for the neutron-events exhibited slower rise times than those for X-rays and -rays. This indicated the capability of neutron--rays discrimination of the detector using the differences in the decay time of the signal current.

Journal Articles

Dyed Polyvinyl Chloride films for use as high-dose routine dosimeters in radiation processing

Mai, H. H.*; Duong, N. D.*; Kojima, Takuji

Radiation Physics and Chemistry, 69(5), p.439 - 444, 2004/04

https://doi.org/10.1016/j.radphyschem.2003.08.006

Times Cited Count：21 Percentile：77.78(Chemistry, Physical)

Characteristics of the polyvinyl chloride films containing 0.11wt% of malachite green oxalate or 6GX-setoglausine with 100m in thickness were studied for use as routine dosimeters in radiation processing. These films show basically color bleaching under $^{60}$ 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 [CClCH(OH)] and 0.15% hydroquinone [HOCHOH]. 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 $^{circ}$ C are constant relative to those at 25 $^{circ}$ C, and the irradiation temperature coefficients for 35-55 $^{circ}$ C were estimated to be (0.43 0.01)%/ $^{circ}$ C. The dosimeter characteristics are stable within 1% at 25 $^{circ}$ C before and 60 days after irradiation.

Journal Articles

Applicability study on existing dosimetry systems to high-power Bremsstrahlung irradiation

Mehta, K.*; Kojima, Takuji; Sunaga, Hiromi

Radiation Physics and Chemistry, 68(6), p.959 - 962, 2003/12

https://doi.org/10.1016/j.radphyschem.2003.08.007

Times Cited Count：3 Percentile：25.79(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.

Journal Articles

Design of an anti-compton spectrometer for low-level radioactive wastes using Monte Carlo techniques

Tsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto

Journal of Nuclear Science and Technology, 39(9), p.957 - 963, 2002/09

https://doi.org/10.3327/jnst.39.957

Times Cited Count：3 Percentile：23.41(Nuclear Science & Technology)

An anti-Compton spectrometer with semi-2 Compton suppression is designed to identify the photons emitted from low-level radioactive wastes from radioisotope usage and nuclear research laboratory. Since the objective sample is massive and large, the system has a full opening towards the sample position. The characteristics and features of the system concerning Compton suppression and reduction of the background component due to natural radioactive source are estimated by the Monte Carlo simulations. The anti-Compton technique is shown to be quite advantageous for the reduction of the surrounding natural background radiation, as well as the suppression of the background for the higher energy photons.

Journal Articles

Simulation of the background for detection system in the indoor environments of concrete buildings

Tsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto

Journal of Nuclear Science and Technology, 38(12), p.1109 - 1114, 2001/12

https://doi.org/10.3327/jnst.38.1109

In order to predict the indoor background spectra to gamma detection systems, the gamma radiation field in a concrete building is studied by the Monte Carlo simulations. The parameters of wall thickness, room shape and dimensions were considered in the modeling. The indoor source geometry was simulated by a spherical layer model with the intention of easy and effective calculations. The model was applied to an unshielded germanium detector and the detection system with a more complex shielding configuration. As the results, we found that the indoor radiation field in concrete buildings can be predicted well with the source geometry of a spherical concrete layer of 25cm thickness and with the source of the natural major three components of the $^{238}$ U series, $^{232}$ Th series and $^{40}$ K that are homogeneously distributed. The simulation model is useful for designing and optimizing gamma detection systems or shielding assemblies.