scholarly journals Improvement of the minimum detectable activity of a free release monitor for small articles

2021 ◽  
pp. 18-18
Author(s):  
Serhii Pohuliai ◽  
Igors Krainukovs
Keyword(s):  
Radiation Detector ◽  
Point Sources ◽  
Minimum Detectable Activity ◽  
Hand Tools ◽  
Measuring Chamber ◽  
Detectable Activity ◽  
Radiation Control ◽  
Detector Volume ◽  
Better Than ◽  
Equipment And Instruments

This paper presents results of the development of a small-sized free release monitor designed for the release of materials, various hand tools, equipment and instruments of nuclear enterprises and laboratories staff that weight up to 50 kg, from radiation control. To increase the registration sensitivity of controlled radionuclides, 12 scintillation units based on a 3"x3" sized NaI (Tl) crystal were used as gamma-radiation detector. Volume of the measuring chamber of the monitor amounted to 200 liters, the thickness of the low-background shielding was chosen 50 mm. The values of the minimum detectable activity of the designed monitor for the point sources 123I, 131I, 99mTc, 18F were better than 100 Bq with measurement time not exceeding 60 s.

scholarly journals Absence of Detectable Radionuclides in Breast Milk in Sendai, Japan in 2012 Even by High-Sensitivity Determination: Estimated Dose among Infants after the Fukushima Nuclear Disaster

2021 ◽  
Vol 18 (11) ◽  
pp. 5825
Author(s):  
Zhaoqing Lyu ◽  
Sani Rachman Soleman ◽  
Tomoko Fujitani ◽  
Yukiko Fujii ◽  
Manal A. M. Mahmoud ◽  
...  
Keyword(s):  
Breast Milk ◽  
High Sensitivity ◽  
Minimum Detectable Activity ◽  
Activity Level ◽  
Internal Exposure ◽  
Dietary Intakes ◽  
Detectable Activity ◽  
Nuclear Disaster ◽  
Exposure Limit ◽  
Fukushima Nuclear Disaster

The aim of this study was to estimate radionuclide levels in breast milk and the transferred dose to their infants in Sendai (100 km from Fukushima), Japan after the 2011 Fukushima nuclear disaster. Radionuclide concentrations were analyzed in 101 specimens of breast milk collected in 2012. Median values for minimum detectable activities were 0.39, 0.34, 1.1, 1.89, and 17.1 Bq/kg for 137Cs, 134Cs, 131I, 110mAg, and 40K, respectively. Only radionuclides from 40K were detected. To estimate potential exposure and radiocesium dose, we assumed that the samples contained each minimum detectable activity level. The mean minimum detectable activity concentrations (standard deviation) of 137Cs and 134Cs were 0.42 (0.15) and 0.37 (0.14) Bq/kg, respectively. Means of estimated dietary intakes of 137Cs and 134Cs among infants were 0.35 (0.12) and 0.31 (0.11) Bq/day, respectively. The committed effective doses of radiocesium in infants aged 3 and 12 months via breastmilk were estimated at 5.6 (2.1) and 3.3 (1.2) μSv/year, respectively. Dietary intakes of 137Cs and 134Cs in breastfeeding mothers were back-calculated at 1.9 (0.71) and 1.7 (0.65) Bq/day, respectively. The study verified no discernible exposure to radionuclides among infants. The most conservative estimates were below the Japanese internal exposure limit of 1 mSv/year.

scholarly journals Minimum Detectable Activity of Pb-210 in Skull From In vivo Measurements: Insights From the Literature

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiangpeng Meng ◽  
Yuanyuan Liu ◽  
Bin Wu ◽  
Jianping Cheng ◽  
Li Wang ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Minimum Detectable Activity ◽  
Active Area ◽  
Semiconductor Detectors ◽  
Background Count ◽  
Radon Exposure ◽  
Detectable Activity ◽  
Retrospective Assessment ◽  
History Of

To address the urgent need for the retrospective assessment of the health conditions of people with a history of appreciable radon exposure, a novel technique that directly measures the characteristic γ-rays emitted from Pb-210 in the living skull was developed. Since the first pioneering study in 1968, this technique has experienced continued advancement over more than half a century, where the limit of detection of Pb-210 is a common criterion to assess the performance of the measuring devices. However, researchers have defined the limit of detection in assorted ways, and the measurement conditions often greatly differ from study to study, both of which significantly challenge interstudy comparisons and obscure how various factors make their impacts. In this work, we reanalyze the reported results in the literature according to the minimum detectable activity (MDA) defined by Currie and investigate the effects of key elements therein. Firstly, we focus on the reported background count rates and analyze their dependence on detector’s energy resolution and active area. Secondly, we turn to the reported calibration factors and conduct analysis in the same manner. Thirdly, we calculate MDA for each study and monitor its dependence on the active area of detector and measurement duration. In the limit of the largest achievable active area (∼75000 mm2), it is found that the asymptotic MDA is approximately 6 (4) Bq and 15 (11) Bq under 30 (60) min measurement using NaI-CsI scintillator and HPGe semiconductor detectors, respectively. Finally, we discuss these asymptotic MDA in the context of estimated Pb-210 activity in the skull resulted from a hypothetical history of radon exposure.

scholarly journals Factors Affecting the Minimum Detectable Activity of Radioactive Noble Gases

2018 ◽  
Vol 16 (3) ◽  
pp. 301-308
Author(s):  
Ji-young Park ◽  
Young Gun Ko ◽  
Hyuncheol Kim ◽  
Jong-Myoung Lim ◽  
Wanno Lee
Keyword(s):  
Noble Gases ◽  
Minimum Detectable Activity ◽  
Factors Affecting ◽  
Detectable Activity

scholarly journals High Resolution Imaging Forty Years Ago

1994 ◽  
Vol 158 ◽  
pp. 337-341
Author(s):  
R. C. Jennison
Keyword(s):  
High Resolution ◽  
Point Sources ◽  
Resolving Power ◽  
High Angular Resolution ◽  
Electromagnetic Spectrum ◽  
High Resolution Imaging ◽  
Resolution Imaging ◽  
Optical Telescopes ◽  
Very High ◽  
Better Than

This conference is concerned with the very high resolution imaging of cosmic sources in many parts of the electromagnetic spectrum. Various techniques are now available and the equipment is often automated and highly sophisticated but the term ‘very high angular resolution’ is comparative. Many of the problems existed over forty years ago when the best resolving power was about half a degree and the two major radio ‘stars’ appeared to be point sources. Very high resolution imaging in those days was the struggle to reach one minute of arc and Hanbury Brown had set his sights on considerably better than one second of arc with the concept of the intensity interferometer. The dream was to achieve a resolving power comparable to that of optical telescopes.

Clarification of the calculation of minimum detectable activity in low-level radioactivity measurements

2016 ◽  
Vol 109 ◽  
pp. 449-451
Author(s):  
K.B. Lee ◽  
Jong Man Lee ◽  
Tae Soon Park ◽  
Sang Han Lee ◽  
Meeyoung Jeong ◽  
...  
Keyword(s):  
Minimum Detectable Activity ◽  
Detectable Activity ◽  
Low Level ◽  
Radioactivity Measurements
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