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Volume 58, Issue 5
Displaying 1-7 of 7 articles from this issue
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Articles
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Yutaka KAMEO, Tomoko HARAGA, Atsushi KATAYAMA, Akiko HOSHI, Mikio NAKA ...2009 Volume 58 Issue 5 Pages 153-160
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSA routine analytical method was developed for the determination of 59Ni and 63Ni in low-level radioactive wastes arising from nuclear research facilities. A separation scheme of 59Ni and 63Ni in waste samples was optimized by considering concentration of interference radionuclides and chemical composition of the waste samples. Concentrations of 59Ni and 63Ni in actual radioactive wastes such as pipes and liquid waste could be well determined by the present analytical method. In the determination, the time required for the chemical separation was five to seven days per ten samples. It was concluded that the present method could be applied to a routine determination of 59Ni and 63Ni in low-level radioactive wastes. In the present experiment, radioactivity ratio of 63Ni/59Ni in pipe samples, which were taken from a nuclear research reactor, was estimated by a computer code(ORIGEN2). Radioactivity ratio of 63Ni/59Ni, obtained by the computer calculation, was ranged from 98 to 109 and that obtained by the present analytical method was 118±6.View full abstractDownload PDF (1166K) -
Tatsuhiko OGAWA, Takuya ABE, Takeshi IIMOTO, Toshiso KOSAKO2009 Volume 58 Issue 5 Pages 161-168
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSNeutron shielding experiment with 49 cm-thick ordinary concrete was carried out at the reactor “Yayoi” The University of Tokyo. System of this experiment is enclosed by heavy concrete where neutrons backscattered from heavy concrete likely affected neutron flux on the back surface of shielding concrete. Reaction rate of 197Au(n, γ), cadmium covered 197Au(n, γ) and 115In(n, n´) in the shielding concrete was measured using foil activation method. Neutron transport calculation was carried out in order to simulate reaction rate by calculating neutron spectra and convoluting with neutron capture cross-section in neutron shielding concrete. Comparison was made between calculated reaction rate and experimental one, and almost satisfactory agreement was found except for the back surface of shielding.
To compose adequate simulation model, description of heavy concrete behind the shielding was thought to be of importance. For example, disregarding neutrons backscattered from heavy concrete, calculation underestimated reaction rate by the factor of 10. In another example, assuming that chemical composition of heavy concrete is equal to the composition adopted from a literature, the reaction rate was overestimated by factor of 5. By making the composition of heavy concrete equal to that based on facility design, overestimation was found to be the factor of 2.
Therefore, adequate description of chemical composition of heavy concrete is found to be of importance in order to simulate neutron induced reaction rate on the back surface of neutron shielding concrete in shielding experiment performed in a system enclosed by heavy concrete.View full abstractDownload PDF (2722K) -
Shigeo BABA, Masanobu HORIE, Mashiho YANAGI, Yuka KATO, Tomoyuki YOSHI ...2009 Volume 58 Issue 5 Pages 169-178
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSUtilization of a low background liquid scintillation counter(Low BG LSC)has been proposed for quantification of ultra-low level 14C in urine. The detector of this system is composed of a central counter and a guard counter, both of which are connected electronically with an anti-coincidence circuit. By this device the background(BG) counts can be decreased approximately to one third in comparison with a conventional liquid scintillation counter(LSC). Three photomultiplier tubes are used in Low BG LSC. High counting efficiency is also achieved by this improvement. 5mL of urine spiked with 14C is counted for 100 minutes and analyzed with the optimal window of multichannel analyzer. The limit of quantification(LOQ) that is defined as radioactivity giving10times standard deviation of BG sample is estimated to be 8.5 mBq per mL urine which is two times improved in comparison with accelerator mass spectrometry. The linearities of sub-becquerel 14C counted for 10 and 100 minutes by use of Low BG LSC are compared with those of LSC. The figure of merit is four times improved in Low BG LSC.View full abstractDownload PDF (1494K) -
Hiromi KAMEYA, Hideyuki OGAWA, Hideo NAKAMURA, Yuhei SHIMOYAMA, Mitsuk ...2009 Volume 58 Issue 5 Pages 179-185
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe detection method of gamma ray irradiated nutmeg was studied with photo-stimulated luminescence(PSL)and electron spin resonance(ESR)spectroscopy. The irradiated nutmeg showed no change to photo-stimulated luminescence spectrum. Sharp signals were detected with ESR method. The representative ESR spectrum of the nutmeg composed of a sextet centered at g=2.0, a singlet at the same g-value and a singlet at g=4.0. This reflects the evidence of three independent radicals in the nutmeg before irradiation. Upon gamma ray irradiation, ESR peak intensity of a singlet signal at g=2.0 was increased. Furthermore, a new signal was appeared. The evaluation of radiation-induced radicals and irradiation effects suggested a new detection method. This would call for an advanced method for the detection of irradiated nutmeg using the defatted nutmeg by ESR.View full abstractDownload PDF (858K)
Materials(Data)
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Nagi MASUDA, Maki MUKAI, Tomonori HOKAMA, Dai MOTOMURA, Tatsuma JAHANA ...2009 Volume 58 Issue 5 Pages 187-193
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe absorbed dose rates in air due to terrestrial gamma radiation in Yomitan-son, a part of Okinawa prefecture, were estimated at 590 points by in situ measurements with NaI(Tl) scintillation survey meters. The mean dose rate was estimated to be 51.4 nGy/h(23.0-112.0 nGy/h). The natural radioactivity for the soils was also determined with a Ge semiconductor detector. The mean concentrations of 238U series, 232Th series and 40K were calculated to be 67.1Bq/kg, 54.7Bq/kg and 384.5Bq/kg, respectively.View full abstractDownload PDF (2161K) -
Eriko HAYASHI, Yuya KOIKE, Keiji KIMURA, Takeshi IIMOTO, Toshiso KOSAK ...2009 Volume 58 Issue 5 Pages 195-207
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSCategory management has been discussed for safety handling of various X-ray generators used for researches. X-ray generators used in universities were classified into five categories according to their grade on safety mechanism. The method of safety handling following “Ordinance on prevention of ionizing radiation hazards” for five categories has been proposed.View full abstractDownload PDF (2084K)
Lecture
Serial Review on Clinical PET Tracers
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Hidehiko OKAZAWA, Takashi KUDO2009 Volume 58 Issue 5 Pages 209-219
Published: 2009
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSPhysiologic evaluation of cerebral blood flow (CBF) and oxygen metabolism provides the basic concept of hemodynamics in impaired circulation. 15O-gas PET has been used for the development of evidence-based medicine in neurosurgical treatment for cerebral vascular disease(CVD). Recently, quantitative perfusion SPECT is used for evaluation of baseline CBF and cerebral vascular reactivity (CVR) after the Acetazolamide (Diamox) challenge test. However, measurement of CBF using H215O is a standard PET method for evaluation of hemodynamics in CVD and neurological degenerative changes in clinical diagnosis. Despite the recent rapid spread of PET and PET/CT facilities, the number of patient examinations with 15O-gas PET scans is declining. For simple measurement of CBF using PET, H215O should be used in those PET centers because the scanning time is quite short as compared to 15O-gas PET scans.View full abstractDownload PDF (1136K)
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