Nagaoka, Mika; Fujita, Hiroki; Aida, Taku*; Guo, H.*; Smith, R. L. Jr.*
Applied Radiation and Isotopes, 168, p.109465_1 - 109465_6, 2021/02
The radioactivities in the environmental samples are analyzed to monitor the nuclear power facilities. The pretreatment of radioactive nuclides of alpha and beta emitters in the environmental samples is performed with acid to decompose organic matter and extract object nuclide such as Sr, U and Pu. However, the pretreatment methods are time-consuming and used many concentrated acid solutions that are unsafe and hazardous. Therefore, we develop to the new pretreatment method using supercritical water instead of acid. Hydrothermal pretreatment of soils (Andosols) from Ibaraki prefecture (Japan) was used to improve methods for monitoring radioactive Sr and U. Calcined samples were pretreated with subcritical or supercritical water (SCW) followed by extraction with 0.5 M HNO solutions. With SCW pretreatment, recoveries of Sr and U were 70% and 40%, respectively. Experimental recoveries obtained can be described by a linear relationship in water density. The proposed method is robust and can lower environmental burden of routine analytical protocols.
Ikebe, Yurie*; Oshima, Masumi*; Bamba, Shigeru*; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi*; Bi, C.*; Seto, Hirofumi*; Amano, Hikaru*; et al.
Applied Radiation and Isotopes, 164, p.109106_1 - 109106_7, 2020/10
Boron Neutron Capture Therapy (BNCT) is a radiotherapy for the treatment of intractable cancer. In BNCT precise determination of B concentration in whole blood sample before neutron irradiation is crucial for control of the neutron irradiation time and the neutron dosimetry. We have applied the Charged Particle Activation Analysis (CPAA) to non-destructive and accurate determination of B concentration in whole blood sample. The experiment was performed at JAEA Tandem Accelerator using an 8 MeV proton beam. The 478 keV ray of Be produced in the B(p,)Be reaction was used to quantify the B, and rays of Co originating from the reaction with Fe in blood was used to normalize the -ray intensity. The results demonstrated that the present CPAA method can be applied to the determination of the B concentration in the blood sample.
Rodriguez, D.; Rossi, F.; Takahashi, Toon; Seya, Michio*; Koizumi, Mitsuo
Applied Radiation and Isotopes, 159, P. 109083_1, 2020/05
Yamamoto, Masahiko; Taguchi, Shigeo; Do, V. K.; Kuno, Takehiko; Surugaya, Naoki
Applied Radiation and Isotopes, 152, p.37 - 44, 2019/10
An online measurement system using an alpha liquid scintillation counter (-LSC) coupled to microchip solvent extraction has been developed. A flow-through cell of -LSC has been prepared by packing PTFE tube into glass tube to combine microchip. Two-phase flow in microchannel has been stabilized by using coiled tube. The Pu in organic phase has been mixed with scintillation cocktail by T-junction connectors. The system separates and detects Pu by online with detection limit of 6.5 Bq/mL, generating only L-level wastes.
Tomita, Jumpei; Takeuchi, Erina
Applied Radiation and Isotopes, 150, p.103 - 109, 2019/08
A rapid analytical method for determining Sr in urine samples (1-2 L) was developed to assess the internal exposure of workers in a radiological emergency. Strontium in a urine sample was rapidly separated by phosphate co-precipitation, followed by extraction chromatography with a tandem column of Pre-filter, TRU and Sr resin, and the Sr activity was determined by ICP-MS/MS. Measurement in the MS/MS mode with an O reaction gas flow rate 1 mL min showed no tailing of Sr at m/z = 90 up to 50 mg-Sr L. The interferences of Ge, Se and Zr at m/z = 90 were successfully removed by chemical separation. This analytical method was validated by the results of the analyses of synthetic urine samples (1.2-1.6 L) containing a known amount of Sr along with 1 mg of each of Ge, Se, Sr and Zr. The turnaround time for analysis was about 10 h, and the detection limit of Sr was approximately 1 Bq per urine sample.
Rodriguez, D.; Rossi, F.; Takahashi, Toon; Seya, Michio; Koizumi, Mitsuo
Applied Radiation and Isotopes, 148, p.114 - 125, 2019/06
Yokoyama, Kaoru; Ohashi, Yusuke
Applied Radiation and Isotopes, 145, p.19 - 23, 2019/03
Dismantled materials generated from nuclear facilities are reused or directed to repository sites. If scrap metals with complicated shapes can be cleared, the amounts of radioactive waste can be reduced. A clearance verification system is constructed to determine the amount of uranium in decontaminated metals in a drum using the 1.001 MeV gamma rays of Pa, produced in the decay of U. The experimental study with simulated waste drums demonstrated that the quantification errors of uranium fall within 25% for 0.5g of uranium.
Hirouchi, Jun; Nishizawa, Yukiyasu*; Urabe, Yoshimi*; Shimada, Kazumasa; Sanada, Yukihisa; Munakata, Masahiro
Applied Radiation and Isotopes, 141, p.122 - 129, 2018/11
Ho, H. Q.; Honda, Yuki*; Hamamoto, Shimpei; Ishii, Toshiaki; Fujimoto, Nozomu*; Ishitsuka, Etsuo
Applied Radiation and Isotopes, 140, p.209 - 214, 2018/10
Ho, H. Q.; Honda, Yuki; Motoyama, Mizuki*; Hamamoto, Shimpei; Ishii, Toshiaki; Ishitsuka, Etsuo
Applied Radiation and Isotopes, 135, p.12 - 18, 2018/05
Shiiba, Takuro*; Kuga, Naoya*; Kuroiwa, Yasuyoshi*; Sato, Tatsuhiko
Applied Radiation and Isotopes, 128, p.199 - 203, 2017/10
We calculated scaled dose point kernels (DPKs) for mono-energetic electron in water (0.015, 0.1, 1.0, and 2.0 MeV) and compact bone (0.010 and 1 MeV) using the latest version of PHITS. Furthermore, we calculated beta-emitting isotopes (Sr, Y, I) DPKs in both water and bone. The simulated results of mono-energetic electron and beta-emitting DPKs were compared with those in literature using different MC codes, such as EGSnrc, GATE6.0, MCNP4C, and FLUKA. All mono-energetic and beta-emitting isotope DPKs calculated using PHITS, both in water and compact bone, were in good agreement with those in literature using other MC codes. The differences were 4% for all mono-energetic electron and beta-emitting isotope DPKs in both water and bone. PHITS provided reliable mono-energetic electron and beta-emitting isotope scaled DPKs in both water and compact bone for patient-specific dosimetry.
Sanada, Yukihisa; Orita, Tadashi; Torii, Tatsuo
Applied Radiation and Isotopes, 118, p.308 - 316, 2016/12
An unmanned helicopter monitoring system (UHMS) was developed to survey the environmental effect of radioactive cesium scattered as a result of the Fukushima Daiichi Nuclear Power Station accident. The UHMS was mainly used to monitor the area surrounding the Fukushima Daiichi Nuclear Power Station six times from 2012 to 2015. Quantitative changes in the radioactivity distribution trend were revealed from the results of these monitorings runs.
Komeda, Masao; Arai, Masaji; Tamai, Kazuo*; Kawasaki, Kozo*
Applied Radiation and Isotopes, 113, p.60 - 65, 2016/07
We designed and fabricated a new type holder that achieved uniform doping under long-term use at JRR-3. The new type holder uses an aluminum alloy and BC particles as filter materials to ensure uniform vertical flux distribution. Although the amount of filter material decreases with long-term use, it was found that the doping distribution did not change by much until 800 h. The lifetime of the new type holder (of the order of hundreds of hours) depends mainly on the amount of trapped radioactive isotopes. This indicates that the decrease in filtering ability over the filter's lifetime is not significant. The filtering ability remains stable for a long time, and the difference in the vertical doping distribution is 1.08 at 1600 h and 1.18 at 4000 h. The irradiation efficiency is expected to increase by 1.7 times when using the new type holder.
Hata, Haruhi; Yokoyama, Kaoru; Ishimori, Yuu; Ohara, Yoshiyuki; Tanaka, Yoshio; Sugitsue, Noritake
Applied Radiation and Isotopes, 104, p.143 - 146, 2015/10
We investigated the feasibility of using support vector machine (SVM), a computer learning method, to classify uranium waste drums as natural uranium or reprocessed uranium based on their origins. The method was trained using 12 training datasets were used and tested on 955 datasets of -ray spectra obtained with NaI(Tl) scintillation detectors. The results showed that only 4 out of 955 test datasets were different from the original labels-one of them was mislabeled and the other three were misclassified by SVM. These findings suggest that SVM is an effective method to classify a large quantity of data within a short period of time. Consequently, SVM is a feasible method for supporting the scaling factor method and as a supplemental tool to check original labels.
Angell, C.; Pedretti, M.*; Norman, E. B.*
Applied Radiation and Isotopes, 98, p.34 - 39, 2015/04
Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki
Applied Radiation and Isotopes, 96, p.52 - 56, 2015/02
Isotope ratios of uranium and plutonium in individual U-Pu mixed particles with various U/Pu ratios were determined by thermal ionization mass spectrometry with a continuous heating method without chemical separation. Prior to the measurements, micron-sized U-Pu mixed particles with U/Pu ratios of 1, 5, 10, 18 and 70 were produced by using certified reference materials CRM U-010 (1%U enriched, NBL) and SRM 947 (NBS) solutions. As a result of isotope ratio analysis, accurate values for U and Pu ratios, except for Pu/Pu, were successfully determined for the particles with all U/Pu ratios. Although some pre-treatment such as chemical separation would need for accurate determination of Pu/Pu isotope analysis, it was shown that this analytical technique has a potential of powerful tool for nuclear safeguards and forensics.
Saegusa, Jun; Kikuta, Yasuaki; Akino, Hitoshi
Applied Radiation and Isotopes, 77, p.56 - 60, 2013/07
Measurements of -ray pulse height distributions were performed for a fallout sample collected at Ibaraki, Japan during the Fukushima accident in March, 2011. The fallout was collected in a pan of water, then evaporated to dryness on a stainless-steel holder. The sample was measured by a germanium detector three times over a year. In the pulse height distribution of the initial measurement, approximately 140 peaks were observed between 50 and 2048 keV energy region. Most of them were either total absorption peak or the sum peak of Te, I or Cs isotopes. Compared to the fallout sampled at the past nuclear accidents, while some nuclides such as Ce and Ru were not detected, Ag etc was prominently observed. Radioactivity concentration of Cs was estimated to be at least 1.410 Bq m, approximately 14% of which was attributed to rainout.
Applied Radiation and Isotopes, 74, p.144 - 151, 2013/04
Effects of lipid compositions and the content ratios on the membrane permeability of liposome have been investigated using soft X-rays as ionizing radiation (IR) sources. Three-component liposome constituted from an unsaturated phosphatidyl choline (PC), a saturated PC, and cholesterol was selected in a series of the study. As the results, following characteristics of IR-sensitive liposome were discovered: (1) A PC with bis-allylic hydrogen is essential as a component of unsaturated PC., (2) Dilinoleoyl PC (DLOPC) is optimal as a component of unsaturated PC., (3) Either distearoyl PC (DSPC) or dipalmitoyl PC (DPPC) is optimal as a component of saturated PC., (4) Lower dose- rate makes the liposome more IR-sensitive., (5) Lower concentration of liposome makes the liposome more IR-sensitive., (6) There is a region for optimal DLOPC content ratio for the IR-sensitive liposome around 5 20 mol%., and (7) There is a region for optimal cholesterol content ratio for preparing a stable liposome around 30 60 mol%. These fundamental laws for IR-sensitive liposome will contribute to understanding of biomembrane damage by IRs and developing a new-conceptual pharmaceutical available in radiotherapies.
Komeda, Masao; Kawasaki, Kozo*; Obara, Toru*
Applied Radiation and Isotopes, 74, p.70 - 77, 2013/04
A new silicon irradiation holder with a neutron filter designed to make the vertical neutron flux profile uniform was studied. Irradiation methods to achieve uniform flux with a filter were discussed using Monte-Carlo calculation code MVP. Validation of the use of the MVP code for the holder's analyses was also discussed via characteristic experiments. It was found that a uniform profile of the vertical flux could be achieved by using the new type holder designed in this study. The vertical uniformity was 3% when using the new type holder, while it was 19.5% when using the normal holder. By using the new type holder, NTD-Si can be increased to 7 tons per year from 4 tons per year.
Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Murakami, Yukihiro*; Harada, Hideo
Applied Radiation and Isotopes, 70(8), p.1531 - 1535, 2012/08
In this study, the MPGA system was characterized for nondestructive multi-element analysis of geological and cosmochemical samples. Among the three offline sorting modes of coincidence data in MPGA, the add-back mode resulted in relatively high analytical sensitivity and the lowest detection limit. The system is highly sensitive to Sm, Gd and Cd. When MPGA detection limits of the studied elements were compared with other cold neutron facilities, MPGA detection limits for Mg, K, S and Cl were improved around one order of magnitude than other facilities under the present experimental conditions, which consists of 8 Clover and BGO detectors. Analysis of the meteorite Orgueil by both MPGA and PGA imply that MPGA can be used for elemental analysis with sufficient accuracy. For some elements (such as Sm, K and Mg) which can Gnot be determined by conventional PGA, due to the spectral interference or lower sensitivity, it was observed that they could be determined accurately (3%) by MPGA.