Refine your search:     
Report No.
 - 
Search Results: Records 1-11 displayed on this page of 11
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Optimization of SIMS-APM for high enrichment uranium particles including higher uranium hydride

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

KEK Proceedings 2021-2, p.146 - 150, 2021/12

no abstracts in English

Journal Articles

Age determination analysis of a single uranium particle for safeguards

Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Esaka, Fumitaka; Yasuda, Kenichiro; Miyamoto, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 328(1), p.103 - 111, 2021/04

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

An analytical technique was developed to determine the age of uranium particles for safeguards. After the chemical separation of uranium and thorium, the $$^{230}$$Th/$$^{234}$$U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a $$^{233}$$U-based reference material comprising a certain amount of $$^{229}$$Th as a progeny nuclide of $$^{233}$$U. The results allowed us to determine the purification age of two certified materials, i.e., U-850 and U-100, which was in good agreement with the reference purification age (61 y). Moreover, the age of a single U-850 particle was determined with a difference of -28 to 2 years from the reference date.

Oral presentation

Cesium isotopic ratio variation about cesium dissolved in river water and included bottom sediment after the FDNPP accident

Tomita, Ryohei*; Matsunaka, Tetsuya*; Honda, Maki*; Satou, Yukihiko; Matsumura, Masumi*; Takahashi, Tsutomu*; Sakaguchi, Aya*; Matsuzaki, Hiroyuki*; Sasa, Kimikazu*; Sueki, Keisuke*

no journal, , 

no abstracts in English

Oral presentation

Chemical state analysis of individual uranium particles with electron backscatter diffraction

Esaka, Fumitaka; Yomogida, Takumi; Tomita, Ryohei; Miyamoto, Yutaka

no journal, , 

Chemical state analysis is important to elucidate the origin of particles and its effect on the environment. However, the analysis is difficult because the amounts of elements in individual particles are considerably small. In the present study, electron backscatter diffraction (EBSD) is applied to the chemical state analysis of individual uranium particles. As a result, uranium particles with diameters of 1$$mu$$m were able to be measured and clear electron backscatter patterns were observed. In addition, the patterns of UO$$_{2}$$ particles were distinguished from those of U$$_{3}$$O$$_{8}$$ particles.

Oral presentation

The Determination of uranium ratios in individual environmental particles

Tomita, Ryohei; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

In the previous study, we developed a combination method of particle manipulation and secondary ion mass spectrometry (SIMS) for removing the interferences from other elements in other particles. Since the particles were selected randomly and manipulated, it caused the problem not to cover the range of $$^{235}$$U/$$^{238}$$U isotope ratio in the sample. In this study, we improved the procedure of analyzing uranium isotope ratios in individual particles by SIMS to cover the range of $$^{235}$$U/$$^{238}$$U in the sample.

Oral presentation

Detailed analysis of individual uranium particles in environmental sample by SIMS and pre-screening measurement introduced into the analysis procedure

Tomita, Ryohei; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

In the previous study, we developed a combination method of individual uranium particle manipulation in scanning electron microscope (SEM) and secondary ion mass spectrometry (SIMS) for removing the interferences from other elements in other particles. Since the particles were selected randomly and manipulated, it caused the problem not to cover the range of $$^{235}$$U/$$^{238}$$U isotope ratio in the sample. In this study, we introduced pre-screening measurement into the procedure of analyzing uranium isotope ratios in individual particles by SIMS to cover the range of $$^{235}$$U/$$^{238}$$U in the sample.

Oral presentation

Isotope ratio analysis of micron sized uranium particle by Large Geometry Secondary Ion Mass Spectrometry instrument

Tomita, Ryohei; Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka

no journal, , 

The research group for safeguards analytical chemistry which belong to Japan Atomic Energy Agency (JAEA) introduced new Large Geometry Secondary Ion Mass Spectrometry (LG-SIMS) instrument (1300-HR$$^{3}$$, CAMECA) to update our capability. LG-SIMS instrument has higher mass resolving power (MRP) than small geometry SIMS (SG-SIMS) instrument we had used. We hope molecular interferences (e.g. Pb, Al, Fe) are removed by LG-SIMS instrument when we analyze uranium bearing particles in environmental sample. In order to obtain the bes LG-SIMS condition for uranium particle analysis, we investigated a relationship between MRP, secondary ion's intensity and peak shape of uranium. One of the most famous molecular interferences of uranium SIMS analysis is PbAl$$^{+}$$ (mass number: 234, 235). If we attempt to remove molecular interferences of the PbAl$$^{+}$$ from uranium mass regions, MRP value of 2741 is required. The MRP of LG-SIMS instrument is defined by entrance and exit slit. We need to keep balance between MRP, secondary ion's intensity and flat-top peak rate. We compared some combination of entrance and exit slit to get better balance. We found the best combination of entrance and exit slit is sized 200 $$mu$$m and 500 $$mu$$m, respectively. LG-SIMS can almost remove PbAl$$^{+}$$ from uranium secondary ions in this condition. This research is part of investigation into safeguards analysis techniques commissioned by nuclear regulatory agency.

Oral presentation

An Examination of environmental sample analyses for safeguard using multi-collector ICP-MS

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

no journal, , 

no abstracts in English

Oral presentation

The Method to reduce particle mixing under automated particle measurement (APM) condition of LG-SIMS

Tomita, Ryohei; Esaka, Fumitaka; Yomogida, Takumi; Miyamoto, Yutaka

no journal, , 

Large Geometry Secondary Ion Mass Spectrometry (LG-SIMS) is one of the strongest tools for analyzing isotope ratios of micron sized uranium particle. LG-SIMS has high spatial resolution of less than 1 $$mu$$m with microprobe mode. However, this capability is bit less under automated particle measurement (APM) condition. If two or more particles are located in a quite narrow area, APM may detect the cluster as one particle. This particle mixing effect shows analytical results including false isotope ratios. In order to investigate how often particle mixing happens and how to solve this problem, we implemented APM to mixed uranium particle standard (U010, U100, U350 and U850) and try to apply particle manipulation with APM. In our experiment, each area (350$$times$$350 $$mu$$m$$^{2}$$) was scanned with an O$$^{2+}$$ primary beam with a current of 1.5 nA for 9 sec. Then, secondary ion images were recorded for circular area with a radius of 8500 $$mu$$m on the center of a sample planchet. The APM detected 5976 particles, and 1943 particles (32%) in them showed false isotope ratios. In addition to particle mixing, U850 cluster was shifted down to around 75% enrichment. The sample showed too high hydride rate, so that $$^{235}$$UH interfered $$^{236}$$U. This interference caused false $$^{236}$$U abundance and lead to false $$^{235}$$U abundance. To solve these problems, 50$$sim$$80 particles were manipulated randomly from another mixed standards planchet and analyzed them by APM.

Oral presentation

Total evaporation for uranium particles generating much uranium hydride formation and isotopic ratio change

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

Secondary ion mass spectrometry (SIMS) analysis of uranium particles for safeguards purpose consists of Automated Particle Measurement (APM) and Microprobe analysis. APM for safeguards sample includes 2400 measurements, each field is analyzed for short time. So, if a sample have particles which generate too much uranium hydride formation on their surface, the APM result, especially $$^{236}$$U abundance, is affected by uranium hydride formation. It causes inaccurate APM result. To investigate what percentage of the entire particle the particle surface causing ratio change account for, total evaporation measurement was implemented for standard uranium particle generating much uranium hydride formation on their surface and uranium isotopic ratio change during the total evaporation measurement was observed. Total evaporation experiment indicated that the number of secondary ions originated from particle surface accounted for 3.1% of all of number of ions sputtered from the entire particle. Based on the total evaporation result, APM conditions, primary beam intensity, measurement time and raster size, combined with the method manipulating particles under scanning electron microscope were optimized to reduce the hydride effect for APM result.

Oral presentation

Quantitative assessment of polyatomic interferences for the measurement of uranium and plutonium isotope ratios at ultra-trace level using MC-ICP-MS

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

no journal, , 

Formation of polyatomic interferences made of an atom of heavy element and atoms in plasma such as argon and oxygen is known to create problems for their measurements using ICP-MS. In this study, quantitative assessment of polyatomic interferences for the measurement of U and Pu isotope ratios at ultra-trace level using MC-ICP-MS was conducted. For U isotopes, significant polyatomic interferences caused by $$^{193}$$Ir$$^{40}$$Ar, $$^{194}$$Pt$$^{40}$$Ar and $$^{196}$$Pt$$^{40}$$Ar were observed at the mass of 233, 234 and 236, respectively. When 1 ppb of natural uranium solution (IRMM184) containing 0.4 ppb of Pt was measured, $$^{234}$$U/$$^{238}$$U isotope ratio was roughly estimated to be two-fold higher than certified value due to the interference. For Pu isotopes, small interference from Pb ($$^{204}$$Pb$$^{40}$$Ar) was observed at the mass of 244 while other obvious interferences were not found.

11 (Records 1-11 displayed on this page)
  • 1