New evaluated radioxenon decay data and its implications in nuclear explosion monitoring

Publication date: Available online 7 March 2018
Source:Journal of Environmental Radioactivity
Author(s): Monica Galan, Martin Kalinowski, Abdelhakim Gheddou, Kassoum Yamba
This work presents the last updated evaluations of the nuclear and decay data of the four radioxenon isotopes of interest for the Comprehensive Nuclear-Test-Ban Treaty (CTBT): Xe-131 m, Xe-133, Xe-133 m and Xe-135. This includes the most recent measured values on the half-lives, gamma emission probabilities (Pγ) and internal conversion coefficients (ICC). The evaluation procedure has been made within the Decay Data Evaluation Project (DDEP) framework and using the latest available versions of nuclear and atomic data evaluation software tools and compilations. The consistency of the evaluations was confirmed by the very close result between the total available energy calculated with the present evaluated data and the tabulated Q-value. The article also analyzes the implications on the variation of the activity ratio calculations from radioxenon monitoring facilities depending on the nuclear database of reference.



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Radionuclide distribution in soil and undecayed vegetative litter samples in a riparian system at the Savannah River Site, SC

Publication date: Available online 7 March 2018
Source:Journal of Environmental Radioactivity
Author(s): Chieh-Ming Wu, Olorunfemi Adetona, Luke Naeher, Brian J. Viner, Tim Jannik, Allan Hepworth, Eric Doman, Teresa Eddy
The aim of this study is to comprehensively investigate radionuclide concentrations in surface soil and un-decayed vegetative litter along four stream systems (i.e. Fourmile Branch, Lower Three Runs, Pen Branch, and Steel Creek) at the Savannah River Site (SRS), Aiken, South Carolina. Soil and litter samples from systematically spaced 12 pairs (contaminated or uncontaminated) of plots along the four streams were analyzed for 16 distinct radionuclide activities. Lower radionuclide concentrations were observed in soil and litter samples collected along Pen Branch compared to the other 3 streams. The anthropogenic radionuclide with the highest activity was ¹³⁷Cs in soil (10.6–916.9 Bq/kg) and litter (8.0–222.3 Bq/kg), while the naturally occurring radionuclides possessing the highest concentration in the samples were ⁴⁰K (33.5–153.7 Bq/kg and 23.1–56.0 Bq/kg in soil and litter respectively) and ²²⁶Ra (55.6–159.9 Bq/kg and 30.2–101.8 Bq/kg in soil and litter respectively). A significant difference (p < 0.05) of radionuclide concentrations between paired-plots across four streams was observed for ²⁴¹Am, ¹³⁷Cs, ²³⁸Pu, ²³⁹Pu, and ²²⁶Ra in both contaminated and non-contaminated samples. ¹³⁷Cs and uranium isotopes had the highest litter-to-soil correlation in contaminated (rho = 0.70) and uncontaminated plots (rho = 0.31–0.41), respectively. ⁹⁰Sr was the only radionuclide with higher radioactive concentrations in litter (12.65–37.56 Bq/kg) compared to soil (1.61–4.79 Bq/kg). The result indicates that 1) historical discharges of anthropogenic ¹³⁷Cs was the most important contributor of radiation contamination in the riparian environment at SRS, 2) ⁹⁰Sr was the only radionuclide with higher concentration in litter than in soil, and 3) no apparent pattern in deposition density in soil or litter along downstream was observed for the radionuclides measured in this study.



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Radiocesium contamination of the moss Hypnum plumaeforme caused by the Fukushima Dai-ichi Nuclear Power Plant accident

Publication date: Available online 7 March 2018
Source:Journal of Environmental Radioactivity
Author(s): Emiko Oguri, Hironori Deguchi
We investigated ¹³⁴Cs and ¹³⁷Cs activity concentrations in the common Japanese moss species Hypnum plumaeforme collected from 32 sites within ca. 100 km radius of the Fukushima Dai-ichi Nuclear Power Plant. A total of 32 samples of H. plumaeforme were collected during the field surveys from November 2013 to September 2014. The maximum radiocesium activity concentrations in H. plumaeforme were 60.9 ± 1.8 kBq kg⁻¹ for ¹³⁴Cs and 123 ± 2.3 kBq kg⁻¹ for ¹³⁷Cs. The mean value for the ¹³⁴Cs/¹³⁷Cs was 1.17 ± 0.05, and the mean Tag value was 0.09 ± 0.13. Positive correlations were obtained between total ¹³⁴Cs + ¹³⁷Cs activity concentrations in H. plumaeforme and the air dose rate with a correlation coefficient (r) of 0.55 (P = 0.001), and between ¹³⁷Cs activity concentration in H. plumaeforme and ¹³⁷Cs deposition density on soil with r of 0.55 (P = 0.001). These results suggest that the perennial moss species H. plumaeforme could be more suitable and useful as a qualitative indicator for the radiocesium pollution compared to vascular plants spreading over the lowlands including human habitation in Fukushima Prefecture.



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Challenges and complexities in remediation of uranium contaminated soils: A review

Publication date: Available online 7 March 2018
Source:Journal of Environmental Radioactivity
Author(s): Rajendran Selvakumar, Govindarajan Ramadoss, Mridula P. Menon, Karuppuli Rajendran, Palanisami Thavamani, Ravi Naidu, Mallavarapu Megharaj
Uranium contamination of soil has been a major concern with respect to its toxicity, accumulation in the food chain and persistence in the environment. Owing to these problems, remediation of uranium-contaminated soils has been investigated by various techniques. This review focuses on the challenges and complexities associated with the remediation of uranium-contaminated soil at field level. Therefore, laboratory studies have been excluded from this review. Challenges faced during remediation of uranium-contaminated soil using various techniques such as microbial/phyto/chemical/material based strategies have been discussed with suitable examples. Various factors that have a major influence on uranium decontamination process in soil such as soil type, uranium speciation, the presence of coexisting ions and organics, etc., have been highlighted. This review brings out the significance of the integrated role of various factors which determine the efficiency of the uranium decontamination process.



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The marine kd and water/sediment interaction problem

Publication date: Available online 7 March 2018
Source:Journal of Environmental Radioactivity
Author(s): R. Periáñez, I. Brovchenko, K.T. Jung, K.O. Kim, V. Maderich
The behavior of marine distribution coefficients is analyzed with the help of numerical experiments and analytical solutions of equations describing kinetic models for uptake/release of radionuclides. The difficulties in measuring true kd in a marine environment perturbed by an external radionuclide source are highlighted. Differences between suspended matter and bed sediment kd are analyzed. The performances of different kinetic models (1-step/2step; single-layer/multi-layer) are studied in model/model and model/experiment comparisons. Implications for the use of models to assess radioactive contamination after an emergency are given; as well as recommendations when kd data are compiled in order to create a useful database.



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Intensity modulated radiotherapy in locally advanced thyroid cancer: Outcomes of a sequential phase I dose-escalation study

To determine the safety and tolerability of dose-escalation using modestly accelerated IMRT in high-risk locally advanced thyroid cancer requiring post-operative radiotherapy, and to report preliminary data on efficacy.

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Treatment of Unruptured, Saccular, Anterior Choroidal Artery Aneurysms with Flow Diversion

Abstract

Background

The region of the brain supplied by the anterior choroidal artery (AChoA) is exquisitely eloquent. Aneurysms arising at or close to the origin of the vessel are not uncommon and damage or occlusion to the vessel can result in devastating consequences. The optimal treatment strategy is yet to be determined.

Objective

We sought to determine the efficacy of flow diversion for the treatment of unruptured AChoA aneurysms.

Method

A retrospective review of our prospectively maintained database was performed to identify all patients with unruptured aneurysms of the AChoA between March 2009 and May 2017. The fundus size, number and type of flow-diverting stent (FD), complications and follow-up data were recorded.

Results

We identified 30 patients (60% female), average age 52.8 ± 10.8 years (range 27–73), with 30 aneurysms. The aneurysms were generally small with a mean fundus diameter of 3.4 mm (range 1–7 mm). Early angiographic follow-up data were available for all patients at which point 15 aneurysms were completely occluded (50%). Delayed angiographic follow-up was available in 24 patients and occlusion was seen in 21 patients (87.5%). Of the patients one developed transient ischemic symptoms after interruption of the antiplatelet medication and another patient had a small embolic infarct with transient symptoms in the periprocedural period.

Conclusion

Flow diversion can be used to successfully treat aneurysms of the AChoA. The treatment carries a high rate of technical and radiological success with a good safety profile.

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