Rn Progeny Research Articles

Estimation of radioactivity in plankton deposited on air conditioner filters in the old area of Mosul city, Iraq

ABSTRACT The essential objective of this study was to estimate 222Rn, 238U, and 226Ra concentrations of plankton samples, along with the risk indices defined by PAEC, Ep, AED and CPPP. These analyzes were carried out on plankton samples from fifteen-alley air conditioner filters in the old Mosul area. In this analysis, using the cumulative monitoring technique of the PM-355 nuclear track detector. The maximum concentrations of radon, uranium, radium and risk indices were observed in Bableksh (sample 5) alley at 77.77(Bq. m−3), 3.74(ppm), 21.46(Bq.kg−1), 0.0084(mWL), 0.3465(WLMY−1), 1.962(mSv.y−1), and 35.31(per 106person). Whereas at Al Hadhira alley the minimum was found to be 39.07(Bq.m−3), 2.05(ppm), (10.78 Bq.kg−1), 0.00422(mWL), 0.1741(WLMY−1), 0.9856 (mSv.y−1), and 17.74(per106 person. The average concentrations of radon, uranium, radium and, risk indices of all studied alleys were 59.156 ± 10.7 (Bq. m−3), 2.803(ppm) ± 0.48, 16.34 ± 4.49(Bq.kg−1), 0.00646((mWL)) ± 0.00011 , 0.2662 (WLMY−1)± 0.0517 , 1.506 (mSv.y−1)± 0.279 , and 27.116 (per 106person)± 5.043 , respectively. Alpha indexes were estimated for all surveyed alleys, in addition to the radioactivity tests and the risk indices. Their values varied between 0.053 and 0.107, with an average 0.081 ± 0.0021. Such levels are significantly smaller than the total dose given by the United Nations Scientific Committee on the effects of atomic radiation, especially at Exposure to 222Rn progeny (Ep) which is within the range of 0.2–10 mSv.y−1 (UNSCEAR). Appropriate correlations between radon concentration with uranium and radium concentration (R2 = 0.8739 and 0.896) have been identified, respectively. The results revealed that the amount of background radioactivity of the alleys of old Mosul area would be within acceptable limits.

Indoor PM2.5 Alpha-Radioactivity is Associated with Biomarkers of Oxidative Stress in COPD Patients

Introduction: Radon decays into progeny that attach to indoor air pollution particles and form unattached clusters. After inhalation, we hypothesize that these serve as vectors for radioisotopes that emit radiation (including α-radioactivity) that promote oxidative damage in patients with COPD.Methods: We recruited 140 patients (97% men, mean (SD) age 72.8 (8.3)) with COPD at VA Boston 5/2013-3/2017 who ran a micro-environmental PM2.5 sampler in their home for 1 week up to 4 times a year (n=414 samples). Samples were analyzed for PM2.5 and black carbon (BC). In 2019, α-radioactivity was measured on each PM2.filter. Since 210Pb (t½=22 years), a Rn progeny, is a parent of 210Po (t½=138 days, α-radiation emitter), α-radioactivity reflects formation of 210Po from 210Pb. Based on the 210Pb decay constant and sampled air volume, α-radioactivity during sampling was estimated. Urinary concentrations of oxidative stress biomarkers, 8-hydroxy-2’-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) were assessed. Mixed effects models with a random intercept for each subject were used to examine associations adjusting for age, race, season, urine collection time, BMI, creatinine, diabetes, heart disease, ambient temperature, humidity, and indoor BC and PM2.5.Results: Median (IQR) PM2.5 α-radioactivity=1.5 (0.64) mBq/m3 (equivalent to 0.056 (0.024) pCi/L); PM2.5=6.9 (5.7) µg/ m3; BC=0.58 (0.27) µg/m3. There was a positive association between natural log (α-radioactivity) and 8-OHdG [5.2% increase (95% CI: 0.9-9.7%) per IQR] and MDA [2.0% increase (95% CI: -2.6-6.8%) per IQR]. Results for 8-OHdG were similar adjusting for PM2.5 (5.4%; 95% CI: 1.1-10.0%) and BC (4.6%; 95% CI: 0.1-9.2%). Results for MDA were similar adjusting for PM2.5 (1.9%; 95% CI: -2.8-6.8%) and were reduced adjusting for BC [0.5%; 95% CI: -4.2-5.4%).Conclusions: Indoor PM2.5 α-radioactivity reflecting 210Pb was positively associated with increased DNA oxidation (8-OHdG) and lipid peroxidation (MDA) in participants with COPD.Funding: ES029637, ES019853, USEPA grant RD-835872

Development of a Gd₂Si₂O₇ (GPS) Scintillator-Based Alpha Imaging Detector for Rapid Plutonium Detection in High-Radon Environments

We developed a Gd2Si2O7 (GPS) scintillator-based alpha imaging detector and demonstrated its effectiveness by evaluating the actual Pu particle and 222Rn progeny. The GPS scintillator plate was prepared by a sintering method. The outer dimensions of the GPS scintillator plate were $5\times 5$ cm, and the scintillator layer was approximately $50~\mu \text{m}$ on a 3-mm-thick high-transparency glass. The plate was optically coupled to a position-sensitive photomultiplier tube (Hamamatsu H8500, Hamamatsu, Japan) with silicone grease. The developed imaging detector exhibited good uniformity; Pu particle activities were accurately evaluated at 14 different positions and the difference in activity was within ±6%. The radon-222 progeny counts were reduced by 65.3% by applying an energy window. Although the Pu/222Rn progeny activity ratio was 1/51, the Pu particle was successfully identified among the 222Rn progeny within the 5-min measurement time. The imaging detector has an excellent ability for detecting Pu among the 222Rn progeny. Thus, this detector is useful for alpha contamination monitoring in high-radon-background environments.

Optimizing parallel particle tracking in Brownian motion using machine learning

In this paper, we present a generic, scalable and adaptive load balancing parallel Lagrangian particle tracking approach in Wiener type processes such as Brownian motion. The approach is particularly suitable in problems involving particles with highly variable computation time, like deposition on boundaries that may include decay, when particle lifetime obeys exponential distribution. At first glance, Lagranginan tracking is highly suitable for a distributed programming model due to the independence of motion of separate particles. However, the commonly employed Decomposition Per Particle (DPP) method, where each process is in charge of a certain number of particles, actually displays poor parallel efficiency due to the high particle lifetime variability when dealing with a wide set of deposition problems that optionally include decay. The proposed method removes DPP defects and brings a novel approach to discrete particle tracking. The algorithm introduces master/slave model dubbed Partial Trajectory Decomposition (PTD), in which a certain number of processes produce partial trajectories and put them into the shared queue, while the remaining processes simulate actual particle motion using previously generated partial trajectories. Our approach also introduces meta-heuristics for determining the optimal values of partial trajectory length, chunk size and the number of processes acting as producers/consumers, for the given total number of participating processes (Optimized Partial Trajectory Decomposition, OPTD). The optimization process employs a surrogate model to estimate the simulation time. The surrogate is based on historical data and uses a coupled machine learning model, consisting of classification and regression phases. OPTD was implemented in C, using standard MPI for message passing and benchmarked on a model of 220 Rn progeny in the diffusion chamber, where particle motion is characterized by an exponential lifetime distribution and Maxwell velocity distribution. The speedup improvement of OPTD is approximatelly 320% over standard DPP, reaching almost ideal speedup on up to 256 CPUs.

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States.

On the basis of lifetime cancer risks, lead-210 (210Pb) and polonium-210 (210Po) ≥ 1.0 and 0.7 pCi/L (picocuries per liter), respectively, in drinking-water supplies may pose human-health concerns. 210Pb and 210Po were detected at concentrations greater than these thresholds at 3.7 and 1.5%, respectively, of filtered untreated groundwater samples from 1263 public-supply wells in 19 principal aquifers across the United States. Nationally, 72% of samples with radon-222 (222Rn) concentrations > 4000 pCi/L had 210Pb ≥ 1.0 pCi/L. 210Pb is mobilized by alpha recoil associated with the decay of 222Rn and short-lived progeny. 210Pb concentrations ≥ 1.0 pCi/L occurred most frequently where acidic groundwaters inhibited 210Pb readsorption (felsic-crystalline rocks) and where reducing alkaline conditions favored dissolution of iron-manganese- (Fe-Mn-) oxyhydroxides (which adsorb 210Pb) and formation of lead-carbonate complexes (enhancing lead (Pb) mobility). 210Po concentrations ≥ 0.7 pCi/L occurred almost exclusively in confined Coastal Plain aquifers where old (low percent-modern carbon-14) groundwaters were reducing, with high pH (>7.5) and high sodium/chloride (Na/Cl) ratios resulting from cation exchange. In high-pH environments, aqueous polonium (Po) is poorly sorbed, occurring as dihydrogen polonate (H2PoO3(aq)) or, under strongly reducing conditions, as a hydrogen-polonide anion (HPo-). Fe-Mn- and sulfate-reduction and cation-exchange processes may mobilize polonium from mineral surfaces. Po2+ occurrence in low-to-neutral-pH waters is attenuated by adsorption.

Parameter sensitivity analysis of the theoretical model of a CR-39-based direct 222Rn/220Rn progeny monitor

Abstract The deposition-based direct indoor 222Rn and 220Rn progeny measurement techniques are mostly affected by the indoor environmental conditions, such as the ventilation, concentration of condensation nuclei, and reactions with the structure and its furnishings. In this study, a theoretical model of a direct 222Rn and 220Rn progeny monitor based on allyl diglycol carbonate (ADC or CR-39) was established to analyse the factors that influence the detection process by using the parameter sensitivity analysis. The aerosol parameters contributed the highest to the variance, followed by the aerodynamic parameters. With respect to the result of the Spearman’s correlation analysis, the aerosol-related and the room-related parameters are positive, whereas the aerodynamic parameters – which affect the turbulence of indoor deposition – are negative. It means that both the attachment process and the deposition process of 222Rn and 220Rn progenies are important to the performance of the progeny monitor.

Intercomparison study of atmospheric <sup>222</sup>Rn and <sup>222</sup>Rn progeny monitors

Abstract. The use of the noble gas radon (222Rn) as a tracer for different research studies, for example observation-based estimation of greenhouse gas (GHG) fluxes, has led to the need of high-quality 222Rn activity concentration observations with high spatial and temporal resolution. So far a robust metrology chain for these measurements is not yet available. A portable direct atmospheric radon monitor (ARMON), based on electrostatic collection of 218Po, is now running at Spanish stations. This monitor has not yet been compared with other 222Rn and 222Rn progeny monitors commonly used at atmospheric stations. A 3-month intercomparison campaign of atmospheric 222Rn and 222Rn progeny monitors based on different measurement techniques was realized during the fall and winter of 2016–2017 to evaluate (i) calibration and correction factors between monitors necessary to harmonize the atmospheric radon observations and (ii) the dependence of each monitor's response in relation to the sampling height and meteorological and atmospheric aerosol conditions. Results of this study have shown the following. (i) All monitors were able to reproduce the atmospheric radon variability on a daily basis. (ii) Linear regression fits between the monitors exhibited slopes, representing the correction factors, between 0.62 and 1.17 and offsets ranging between −0.85 and −0.23 Bq m−3 when sampling 2 m above ground level (a.g.l.). Corresponding results at 100 m a.g.l. exhibited slopes of 0.94 and 1.03 with offsets of −0.13 and 0.01 Bq m−3, respectively. (iii) No influence of atmospheric temperature and relative humidity on monitor responses was observed for unsaturated conditions at 100 m a.g.l., whereas slight influences (order of 10−2) of ambient temperature were observed at 2 m a.g.l. (iv) Changes in the ratio between 222Rn progeny and 222Rn monitor responses were observed under very low atmospheric aerosol concentrations. Results also show that the new ARMON could be useful at atmospheric radon monitoring stations with space restrictions or as a mobile reference instrument to calibrate in situ 222Rn progeny monitors and fixed radon monitors. In the near future a long-term comparison study between ARMON, HRM, and ANSTO monitors would be useful to better evaluate (i) the uncertainties of radon measurements in the range of a few hundred millibecquerels per cubic meter to a few becquerels per cubic meter and (ii) the response time correction of the ANSTO monitor for representing fast changes in the ambient radon concentrations.

A REMOTE CONTINUOUS AIR MONITORING SYSTEM FOR MEASURING AIRBORNE ALPHA CONTAMINATION.

We developed a remote continuous air monitoring (RCAM) system. The RCAM system consisted of a personal air monitor and a robot. The personal air monitor (poCAMon, SARAD, Germany) had a 400-mm2 ion-injected silicon detector and a membrane air filter with 25 mmφ. The personal air monitor provides the alpha energy spectra for any measurement time interval. Demonstration measurements were taken underground at the Mizunami Underground Research Laboratory and at a poorly ventilated concrete building. The RCAM system was remotely operated and successfully measured the 222Rn progeny even though the relative humidity was almost 100%. In the measured alpha spectra, the peaks of 218Po (6.0-MeV alpha) and 214Po (7.7-MeV alpha) were clearly identified. Our developed monitor is promising for alpha dust monitoring in a high gamma-ray environment or contaminated areas where a worker cannot safely physically enter.

ASSESSMENT OF DOSE DUE TO AMBIENT Rn222/Rn220 PROGENY IN DIFFERENT DWELLINGS OF JAMMU AND KASHMIR STATE, INDIA.

The un-attached part of radon (222Rn) progeny is one of the imperative variables for the definitive evaluation of the effective dose from the radon exposure perspective, and it might fluctuate enormously in various ecological conditions. Therefore, estimate dispersion of 222Rn/220Rn progeny, un-attached part and aerosol concentration was estimated in an indoor domain of Jammu and Kashmir State, India utilizing progeny deposition based sensors. Distinctive sorts of residence were picked up for this exploratory examination and maximum 222Rn and thoron (220Rn) descendants concentration was found in working environments or workplaces when contrasted from other abodes because of low ventilation rate. The average evaluated portions of an unattached for 222Rn and 220Rn are 0.29 and 0.26 and in addition, observed to be most extreme in work environments. The age-dependent dose has furthermore been determined utilizing attached and un-attached 222Rn/220Rn progeny concentrations. The dose to trachea-bronchial region and aerosol concentrations has additionally been estimated.

Radon and its progenies variation in the urban polluted atmosphere of the Mediterranean city of Thessaloniki, Greece.

Radon and Rn progenies' concentrations were determined in the urban polluted atmosphere of Thessaloniki's city center using two experimental procedures: (i) filter with 0.8-μm porosity measured using α-counting technique determining the radon equilibrium equivalent concentration (CEER), which varies from 2.6 to 8.9 Bq m-3, and (ii) filter with 0.3-μm porosity measured in the laboratory using γ-spectrometry determining 214Pb activity concentration 1.3-7.5 Bq m-3 and 214Bi activity 3.1-11.5 Bq m-3. Strong daily correlation with the relative humidity is presented, in association to an inverse correlation with the temperature gradient. Radon and its daughter's concentration correlate well smoke particles' content because radon is trapped inside them due to their high effective porosity, and so the Rn daughter collection in the filter increases. Gas pollutants have similar daily distribution with the radon activity, while SO2 levels are correlated the best with 214Pb and 214Bi concentrations, as Pb is more chemically associated to sulfuric complex ions than nitric formation in presence of vapors. The lower 214Pb/ 214Bi activity ratio appeared during the highest temperature gradient and amount of vapors, smoke, and gases giving rise to high formation of ultrafine aerosol particles. The ultrafine aerosol creation boosts 214Pb recoil effect taken place during 218Po α-decay, so 214Pb nuclei become free starting the clustering process yet again having ingrowth coefficient ~ 0.1 nm2 s-1 regarding accumulation mode aerosols.

The determination of equilibrium factor of radon and thoron using LR-115 type II detector in a selected area from Basra Governorate, Iraq

The inhalations of radon 222Rn progeny are the most important source of irradiation of the human respiratory. Studies of underground miners of uranium and other minerals have provided reasonably firm estimates of the risk of lung cancer associated with exposure to radon progeny. It is well established that the absorbed radon dose in the lung is mainly due to radon progeny, but not the radon gas itself. Therefore, long-term measurements of the concentrations of radon progeny or the equilibrium factor F, together with a measurement or an estimation of the aerosol size distribution, are needed to accurately assess the health hazards contribution from radon progeny. Radon, thoron and their progeny are present in the indoor atmosphere as free and bound fractions. The ventilation level in the house played an important effect on the equilibrium between them. This paper presents the results of the measurement of the equilibrium factor F between radon, thoron and their progenies in dwellings and estimates an experimental relationship for the F-factor based on track density instead of typical value of UNISCEAR (about 0.4), which varies significantly with time and place. In this paper, we described a method of theoretical calculation of F and experimentally determined the F-factor using LR-115 type-2 plastic track detectors in closed and bare mod. The exposures were made with a cup and bare dosimeters distributed in 34 houses distributed in different locations of Basra Governorate. The measured F-factor between radon and progeny varied from 0.01 to 0.98 with an average value of 0.38 while the same factor for thoron and progeny was found to vary from 0.0004 to 0.3794 with an average value of 0.0877. These values were in a good agreement with the global F-factor estimated by ICRP. In present investigation about the F-factor, theoretical calculations using graphical solutions supported by experimental technique have been carried out. It is found that the globally assumed F-factor from UNSCEAR and our experimentally obtained value are in good agreement. For a more accurate estimation of the effective dose, one should measure the F-factor at each site considering all the effective parameters like the ventilation factors. The equilibrium factor was found to be small in some houses due to the very intensive ventilation system in the house.

Validation of a rapid, conservative transuranic alpha activity estimation method in air samples

In air filter assay for radiological emergency response, radon (222Rn) and thoron (220Rn) progeny are known interferents to transuranic activity estimation. Previous work detailed a conservative, graded approach for TRU alpha activity estimation from air samples void of transuranic activity yet containing varying amounts of radon and thoron progeny. Validation of this method to produce rapid, conservative and defensible transuranic alpha activity estimates was accomplished through introduction of surrogate transuranic activity, 239Pu and 230Th check sources, along with the naturally occurring radioactive progeny from an environmental air filter. Following air collection, the filter was centre hole-punched with the transuranic check source placed underneath the filter during counting. With the surrogate transuranic activity introduced into the measurement, verification of the previously studied methodology for rapid transuranic activity estimation was determined with quantifiable conservative bias. 70 environmental filters with various levels of radon progeny and air sampling duration were collected; 35 examined with the 239Pu check source and 35 studied with the 230Th check source. To characterise the expected transuranic activity introduced to the counting experiment without the environmental interferents of radon and thoron progeny, 30 blank filters were counted using the described experimental setup with each of the respective surrogate sources. Following characterisation of the sources with blank filters, transuranic activity estimation comparison against the 70 environmental filters with natural background radioactive progeny interferents was accomplished. This work contributes to the comprehensive analysis of operational air samples by detailing validation results for a rapid and conservative transuranic alpha activity estimation methodology.

Radon Off-Gassing From Military Artifacts.

Military historical artifacts found in museum displays and storage locations were analyzed for their Ra and Rn progeny activities to determine the fraction of Rn lost to the environment. Gamma-ray spectroscopy using high-purity germanium detectors was used to determine Ra activity and infer Rn activity based on Pb and Bi. Analyses were conducted without affecting the structural integrity of the artifacts. Ra was measured directly after correction for solid angle and finite sample-detector distance. Although Rn can be similarly analyzed, the collection in charcoal of Rn off-gassed from the artifact after the establishment of secular equilibrium was preferable. Rn off-gassing rates vary greatly between the six devices studied, with a maximum off-gassing rate of 1,850 ± 50 Bq h. Large variations in off-gassing rate were also observed between an additional 30 nominally identical dials, with a mean and standard deviation of 7.7 ± 7.1 Bq h. The work is not predictive of airborne Rn activity within museums, where building size and ventilation are significant and unique to each location. However, the significant off-gassing rates and their large variation suggest that Rn activities may be elevated in enclosed locations, such as aircraft cockpits and storage facilities.

AN EXPERIMENTAL CHAMBER FOR TESTING ABATEMENT EFFECTS OF RADON EXPOSURE WITH DIFFERENT MEASURES.

For more effective testing the abatement effects of radon exposure with different counter measures, an air-conditioned laboratory room was reformed as an experimental chamber. Based on the well control and real time monitoring of concentrations of 222Rn, its attached and unattached progeny and their size distributions, the chamber could provide three modules corresponding to ventilation, source reduction and filtration for abating radon exposure. Preliminary results showed that the chamber was useful for testing the abatement effect of indoor radon exposure.

Rn progeny diffusion, deposition and track distribution in diffusion chamber with permeable membrane

Objective of this work is to define method by which sensitivities of CR-39 and LR-115 in diffusion chamber could be determined. Method is based on initial physical processes that occurs in diffusion chamber: diffusion, deposition and decay of radon (isotopes 222Rn and 220Rn) and their progeny. Cylindrical shape of chamber was considered due to availability of experimental data for validation of presented method. The shape was not limitation factor and can be extended to any geometry. Diffusion equations for radon in two mediums (membrane and chamber volume) and their progeny in volume were solved using Finite Difference Method – FEM, and solutions are their spatial distributions inside of diffusion chamber. Calculation of flux towards the chamber walls determine distribution pattern and deposited progeny fractions. It has been shown that volume and deposited distributions are not uniform. Visible tracks on CR-39 for defined etching conditions are determined by considering range of alpha particles in air and empirical critical angle function θC=θC(E). For LR-115 mean critical angle of 〈θc〉=500 and energy window from Emin=1.7MeV to Emax=4.2MeV was adopted from literature to determine number of visible tracks. The track density distributions on detector are found to be non-uniform and radially dependent.Thickness of permeable membrane has important influence on presence of thoron and its progeny tracks on detector. Sensitivities of CR-39 and LR-115 in diffusion chamber were determined using method presented in this work and compared with other theoretical models and experiment with good agreement. This shown applicability of the presented method.One of important conclusion is that detector sensitivity, given as one simple number, is not the best parameter for calibration due to the existence of radial variation of track density.For cylindrical chamber with 10cm length and 4cm radius, covered with membrane in form of one-layer filter paper 0.25mm thickness, and for equal concentrations of 222Rn and 220Rn in front of the chamber, contribution of 220Rn and its progeny to total track density is about 3%.

Determination of 7Be, 210Pb and 22Na Activity in Air and Rainwater samples by Gamma-ray Spectroscopy

The activity concentration of cosmogenic radionuclides in atmospheric aerosol has been used in many applications, such as air mass transport models and solar activity reconstructions. One of the most studied cosmogenic radionuclides is 7Be which is being monitored at the Nuclear Engineering Department of the National Technical University of Athens (NED- NTUA) since many years, with high accuracy and precision. Sodium-22 is another cosmogenic radionuclide met in such studies, however less reported due to its very low activity concentration, of the order of 1 μBq/m3 [1], [2] – roughly four orders of magnitude lower than that of 7Be. Besides cosmogenic radionuclides, radionuclides of terrestrial origin like the 222Rn progeny 210Pb are also used in atmospheric aerosol studies. Lead-210 serves as an ideal tracer of continental air masses because 222Rn emission from oceans and lakes is negligible (<1%) compared to land sources. However, its deposition exhibits geographic and seasonal variations depending on 226Ra content of the top soils, soil-porosity and meteorology of a particular region [3]. Values reported for 210Pb activity in the air range from 0.1 to 3.4 mBq/m3 [4]. During this research, an investigation regarding the detection of 210Pb and 22Na in atmospheric aerosol and the determination of 7Be/22Na ratio has been conducted at NED-NTUA. Sampling and analysis methods were appropriately selected to allow for the detection of all three nuclides in aerosol samples. In order to study the role of precipitation in surface air 7Be, 210Pb and 22Na activity concentration, a procedure for collecting and analyzing rainwater was also developed. From the results obtained so far it is concluded that with the sampling and analysis procedures followed, 210Pb can be easily determined with reasonable accuracy. As far as 22Na is concerned, it was concluded that it can be detected although with high uncertainty, since its activity concentration is within the limits of detection.

Limitations in the assessment of radon dose: the role of activity measurements in the human body

Radon-222 is classified in the Group I of the human carcinogens. The in situ decay of inhaled 222Rn and its short-lived decay products (T1/2 <30 min) is the main source of radiation burden to the general population of natural origin. The corresponding effective dose is routinely calculated as the product of the 222Rn concentration in air, a predetermined dosimetric constant and a factor that depends on the space type (e.g. residential or public building, cave, mine, etc). However, in practice, there are large spatial and temporal variations in the activity ratio of each progeny to 222Rn in air, the characteristics of the progeny carrying particles and the metabolism of each progeny depending on air quality, as well as differences in the anatomic and physiological characteristics between individuals, that vary substantially even with time. Therefore, the currently employed dosimetric approach may introduce large uncertainties. In the hypothetical case of acute deposition and full retention in the human body of equal activities of all 222Rn progeny, about 93% of the effective dose is due to the decaying 214Po. The 214Po activity can be assessed by measurement of its γ-emitting precursor, 214Bi, which is in full equilibrium with 214Po in the human body. The 214Bi activity can be measured using a high-sensitivity whole-body counter with high counting uniformity, such as the one in use at the Ioannina University Medical Physics Department. Its detection efficiency and its dependence on body shape and size were assessed by Monte Carlo simulations. Measurements carried out in healthy adult volunteers residing at a short distance from the counter, indicated a mean total body 214Bi activity (TBBi) of ~100 Bq during the cold season of the year and lower during the hot one. Higher mean TBBi levels were found in male than in female adults. Therefore, TBBi measurements may allow for accurate radon-related risk assessment on individual base.

Alpha spectrometry with the inexpensive open-source detector Alphaino

Abstract A photodiode-based inexpensive detector working as counter and spectrometer for alpha particles , named Alphaino , is described and analyzed in depth. Prior to detector construction, Monte Carlo simulations by means of MCNPX ver. 2.7.0 code have been carried out to select the most suitable sensitive element for the intended applications. The detector has been tested for low-rate alpha-particle counting and spectroscopy , demonstrating a maximum achievable count rate of 4 ⋅ 1 0 3 s−1, with an energy resolution corresponding to a Full Width Half Maximum of 160 keV over the entire energy range of measured alpha, namely 4 − 6 . 5 MeV, the intrinsic efficiency being 100%. Alphaino can be used for fast and qualitative analyses to radionuclides identification, and quantitative analyses when radionuclides monitored are characterized by well distinguished energy lines in spectra. Its applications will include 222 Rn progeny monitoring by mechanical air sampling on a millipore filter, and disposable applications to qualitative measuring of potentially alpha-contaminated liquids (containing plutonium isotopes) by a droplet put on the photodiode itself, for a quick and cheap evaluation prior to initiate proper chemical treatments to classical alpha spectrometry by electrodeposition . Alphaino is completely open-source. The repository for the project is available on GITHUB at https://github.com/bemxgm/Radon-Monitor .

Quantification of an alpha flux based radiological dose from seasonal exposure to 222Rn, 220Rn and their different EEC species

This study summarizes the seasonal experimental data on the activity concentrations of indoor 222Rn (Radon), 220Rn (Thoron) and their progeny in Mansa and Muktsar districts of Punjab (India) using LR-115 solid state nuclear track detector based time integrated pin-hole cup dosimeters and deposition based progeny sensors for the assessment of radiological dose. The indoor 222Rn concentration was observed higher in the rainy and winter seasons while 220Rn concentration was observed higher in the winter season. However, Equilibrium Equivalent Concentrations (EECs) of 222Rn and 220Rn exhibited distinct seasonal behaviour unlike their parent nuclides. The average equilibrium factors for 222Rn (FRn) and 220Rn (FTn) were found 0.47 ± 0.1 and 0.05 ± 0.01, respectively. The annual arithmetic means of unattached fractions of 222Rn ({f}_{p}^{Rn}) and 220Rn ({f}_{p}^{Tn}) were found to be 0.09 ± 0.02 and 0.10 ± 0.02, respectively. The attachment rate (XRn) and attachment rate coefficients (β) of 222Rn progeny were also calculated to understand the proper behaviour of progeny species in the region. A new alpha flux based technique has been proposed and used for the assessment of absorbed dose rate and annual effective dose rate for radiation protection purpose.

Development of an alpha dust monitor using a GPS scintillator plate

A dust monitor with a silicon surface barrier detector (SSBD) is introduced at a nuclear fuel facility to detect airborne contamination of 238Pu and 239Pu released by past accidents. However, an SSBD frequently produces false alarms, especially in a room with high humidity. To develop a highly reliable dust monitor, we developed an alpha-particle spectrometer based on a cerium-doped Gd2Si2O7 (GPS) scintillator plate and a photomultiplier tube (PMT). The GPS scintillator plate is hexagonal and 50 mm in diameter, and the scintillator layer is approximately 40 μm. An output signal from the PMT is amplified by a preamp and transferred to an MCA. Then, an energy spectrum is displayed in real time. The 241Am alpha source, Rn progeny collected on the air filter, and a PuO2 particle were measured by our developed spectrometer. The energy resolution for 5.5-MeV alpha particles was ∼11.9% ± 0.2% of the FWHM. The efficiency was 92%, and it had a uniform sensitivity. By applying an energy window, the count-rate of the Rn progeny decreased by 77%. The GPS scintillator plate was able to measure the alpha spectrum even though the GPS scintillator got wet. Therefore, the alpha dust monitor using the GPS scintillator plate is ideal for detecting alpha-particle emitters in places lacking temperature and humidity controls, such as the outside of buildings.