Analysis of cesium isotope compositions in environmental samples by thermal ionization mass spectrometry – 1. A preliminary study for source analysis of radioactive contamination in Fukushima prefecture

Shibahara, Yuji; Kubota, Takumi; Fujii, Toshiyuki; Fukutani, Satoshi; Ohta, Tomoko; Takamiya, Koichi; Okumura, Ryo; Mizuno, Satoshi; Yamana, Hideaki

doi:10.1080/00223131.2014.891954

Cited by 52 publications

(63 citation statements)

References 16 publications

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“…Cs were determined by TIMS, and a TaO activator was used to enhance the counting efficiency. The effect of isobaric barium can be ignored owing to the fact that it has a different ionization energy than cesium does [6].…”

Section: Methodsmentioning

confidence: 99%

“…The seaweed sample was dried and incinerated without cleaning. An aliquot of these incinerated samples was dissolved in HNO 3 and then purified with ammonium phosphomolybdate (AMP) [6] in order to recover the cesium fraction. The seawater sample was treated with AMP-PAN in order to concentrate the cesium, which was eluted with NH 4 OH.…”

Section: Methodsmentioning

confidence: 99%

“…In the ionization process, isobar nuclides (in this study, cesium and barium) are separated according to their different ionization energies. We investigated various environmental samples by using TIMS [6], which is suitable for determining the isotopic ratios of radioactive cesium in the environment for long periods of time.…”

Section: Introductionmentioning

confidence: 99%

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Isotopic Ratio of 135Cs/137Cs in Fukushima Environmental Samples Collected in 2011

Kubota

Shibahara

Ohta

et al. 2016

Radiological Issues for Fukushima’s Revitalized Future

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The isotopic ratios of radioactive cesium derived from the Fukushima accident were determined by "-spectrometry and thermal ionization mass spectrometry (TIMS). In order to ascertain the initial ratios at the time of the accident, environmental samples collected during 2011 were used for the analysis. Soil, litter, and seaweed were incinerated, and the cesium contained therein was adsorbed into ammonium phosphomolybdate powder. The cesium in the seawater was adsorbed into AMP-PAN resin (Eichrom Technologies, LLC); its recovery ratio was almost one without the carrier being added. Incinerated samples and the AMP-PAN resin were then measured by "-spectrometry. The cesium solution recovered from adsorbers was subjected to TIMS measurements. The isotopic ratios of 134 Cs/ 137 Cs and 135 Cs/ 137 Cs were found to be independent of the type of sample in question, as well as the sampling location; the ratios were 0.07 and 0.36 (decay correction: 11 March 2011), respectively, which differ from the results of atmospheric nuclear tests (i.e., 0 and 2.7, respectively). This difference in the ratio of 135 Cs/ 137 Cs will contribute to estimations of the origin of radioactive contamination in the future.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Isotopic Ratio of 135Cs/137Cs in Fukushima Environmental Samples Collected in 2011

Kubota

Shibahara

Ohta

et al. 2016

Radiological Issues for Fukushima’s Revitalized Future

Self Cite

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“…Figure 11.1 shows the appearance and cross-sectional drawing for the CZT detector assembly (Kromek GR1 TM ) used in this study. The sensitive region of the detector is made of CdZnTe semiconductor crystal, and the dimension of the sensitive region is 1 cm 3 .…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, high dose rates more than tenth Sv h 1 impede the precise spectrometry using the Ge detectors caused by their own high sensitivity to gamma rays. In our measurement campaign for investigating the isotropic ratio of radiocesiums [3,4], the Ge detector used was not able to show its high energy resolution when measured in higher-dose rate areas. This was caused by broadening each peak in the pulse height spectrum due to overlapping of too many events incoming the detector sensitive region.…”

Section: Introductionmentioning

confidence: 99%

In Situ Environmental Radioactivity Measurement in High–Dose Rate Areas Using a CdZnTe Semiconductor Detector

Kowatari

Kubota

Shibahara

et al. 2016

Radiological Issues for Fukushima’s Revitalized Future

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For the purpose of determining a surface deposition density on soil for radio-cesiums, a CdZnTe (CZT) semiconductor detector whose crystal has dimensions of 1 cm cubic was applied to the in situ environmental radioactivity measurement in deeply contaminated areas in Fukushima region. Even in highdose rate areas where pulse height spectra weren't able to be properly obtained by the conventional high-purity Ge (Hp-Ge) semiconductor detector, proper pulse height spectra were obtained by the CZT detector with certain accuracy. Results of deposition density on soil for 134 Cs and 137 Cs derived from net peak areas by the CZT detector seemed consistent, comparing with those measured by the Japanese government. Air kerma rates were estimated by the same pulse height spectra for determining surface deposition density on soil for radio-cesiums. Estimated results showed almost the same values as obtained by the NaI(Tl) scintillation survey meter. The results indicate that the CZT detector can be applied to rapid and simple in situ gamma ray radioactivity measurement in higher-dose rate areas whose dose rates exceed several tenth Sv h 1 . The study also strongly supports that the CZT detector is one promising candidate for the detector to be used for checking the effect of decontamination works and for long-term monitoring in heavily contaminated areas.

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Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

Snow

Snyder

Delmore

2016

Rapid Comm Mass Spectrometry

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Cesium isotopic analyses provide a powerful tool for source term discrimination of environmental radiocesium contamination at the FDNPP site. For higher precision source term attribution and forensic determination of the FDNPP core conditions based upon cesium, analyses of a larger number of samples from locations to the north and south of the FDNPP site (particularly time-resolved air filter samples) are needed.

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Analysis of cesium isotope compositions in environmental samples by thermal ionization mass spectrometry – 1. A preliminary study for source analysis of radioactive contamination in Fukushima prefecture

Cited by 52 publications

References 16 publications

Isotopic Ratio of 135Cs/137Cs in Fukushima Environmental Samples Collected in 2011

Isotopic Ratio of 135Cs/137Cs in Fukushima Environmental Samples Collected in 2011

In Situ Environmental Radioactivity Measurement in High–Dose Rate Areas Using a CdZnTe Semiconductor Detector

Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

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