HPGe Detector Research Articles

Assessment of natural radioactivity in the Higher and Tethys Himalayan Rocks along Manali-Leh Highway, India.

The Higher and Tethys Himalayan region of NW-Himalaya is less explored from the natural radioactivity mapping assessment, though geologically and tectonically, this region is still active. The concentration of primordial radionuclides (226Ra, 232Th, and 40K) in rock samples of the Manali-Leh Highway region of the Himalayas is determined in the present study using the HPGe detector. The radiological hazard parameters are also estimated in terms of radium equivalent activity (Raeq), annual effective dose (Ein and Eout), hazard indices (Hin, Hex, Hα, and Hγ), and gamma absorbed dose rate. SEM-EDS analysis was used to understand the mineralogical composition of the rocks. The activity concentration of 226Ra, 232Th, and 40K radionuclides varies from 1.4 ± 0.9 to 25.3 ± 1.2, 0.7 ± 0.5 to 59.6 ± 1.6, and BDL (below detection limit) to 830.3 ± 45.7Bqkg-1, with an average value of 13.0 ± 1.0, 21.7 ± 1.0, and 243.7 ± 25.2Bqkg-1, respectively. The average of Raeq in the study region lies within the safe limit of 370Bqkg-1. The hazard indices have values < 1, indicating no radiological hazards to the population from the rocks. The annual effective dose also has values less than the global average value. This study revealed that the rocks of the Higher Himalayan region have a higher concentration of natural radioactivity, while the Tethys Himalayan rocks have lower concentrations of 226Ra, 232Th, and 40K radionuclides. The origin of rocks from different lithologies may be the reason for the natural radioactivity variation. The average concentrations of primordial radionuclides in the region are within the world average indicating that the rocks of the region are safe to be used for different purposes.

Radionuclides' Dispersion from Coal-Fired Brick Kilns: Geo-Environmental Processes, Potential Risks and Management.

In order to investigate the distributions and possible dispersion mechanism(s) of naturally occurring radioactive materials (NORMs: 226Ra, 232Th, and 40K) from coal-based brick kilns, a systematic set (n = 60) of coal, ash, surface-soil, and subsurface soil samples were analyzed. High-quality analytical data of U, Th and K obtained from HPGe detector and TRIGA Mark-II research reactor-based neutron activation analysis were converted to the corresponding radioactivities. Average (n = 10) radioactivities of 226Ra, 232Th, and 40K in coal samples were 15.6, 16.7, and 145.5Bq.kg-1, respectively, where only 40K surpassed the corresponding global mean value. Average (n = 10) radioactivities of 226Ra, 232Th, and 40K in ash samples were 62.7, 88.5, and 521Bq.kg-1, respectively, where only 226Ra was within the established limit. In soil samples, average (n = 40) activities of 226Ra, 232Th, and 40K were 62.7, 95.1, and 641Bq.kg-1, respectively, which have surpassed the corresponding worldwide mean values. The observed differences in activity levels between soil samples collected near and far from the kilns, as well as between topsoil and subsoil samples, suggest the presence of distinct transport mechanisms for NORMs within the pedosphere. Dispersions of NORMs from the brick kilns to the ambient pedosphere are largely governed by aerodynamic convection and hydrodynamic leaching. These mechanisms are also influenced by geochemical mobility and relative solubility of NORMs, as well as factors such as rainfall patterns and wind-flow direction. Radiological indices invoke long-term carcinogenic-risks, whereas aerodynamic convection of finer particles (coal fly ash) from chimneys can cause significant health hazards to the nearby dwellers. Scientific processes as well as public awareness are essential to mitigate the risks.

Assessment of radioactive nuclides and heavy metals in soil and drink water in Lahij city, Yemen

This study was conducted in Lahij city, Yemen, to evaluate the concentrations and potential health risks of natural radioactive nuclides and heavy metals in soil and drinking water. A total of 21 soil samples and 17 water samples were collected from various locations. A high-purity germanium gamma detector HPGe was used to measure the concentrations of 40K, 232Th, and 226Ra in all samples, along with the concentrations of heavy metals. In soil samples, the average concentrations of 40K, 232Th, and 226Ra were 731.5, 30.7, and 28.16 Bq kg−1, respectively. While some samples showed higher than permissible levels for 226Ra and 232Th, the overall average remained within acceptable limits. However, 40K levels were almost twice the recommended global limits. In water samples, the average concentrations of these nuclides were 5.38, 0.73, and 0.66 Bq L−1, all within the global safety limits. Radiological risk assessments for soil indicated an average radium equivalent activity (Raeq) of 124.4 Bq kg−1, absorbed dose rate in air of 59.9 nGy h−1, annual effective dose rate of 0.07 mSv y−1, outdoor excess lifetime cancer risk (ELCR) of 0.26 × 10−3, and annual gonad equivalent dose (AGED) of 336.6 mSv y−1. Risk indices, including the activity concentration index (Iγ), external hazard index (Hex), and internal hazard index (Hin), averaged 0.48, 0.34, and 0.41, respectively, all below global limits except for AGED, which slightly exceeded the recommended level. For drinking water, the total ingestion dose was calculated for different age groups. The average doses for infants, children, and adults were 0.15, 0.27, and 0.19 mSv y−1, respectively. The doses for children and adults exceeded the permissible limits, while those for infants were within safe levels. Heavy metal concentrations were measured in all samples, and the Hazard Quotient (HQ) was calculated. In soil samples, HQ values for all metals >1, indicating potential health risks. In water samples, HQ values were also >1 for all metals except vanadium (V) and iron (Fe). To reduce the dangers associated with radioactive nuclides and heavy metals, regular monitoring and cleanup are crucial, and further research is needed to understand contamination sources and long-term health impacts.

Gamma ray registration efficiency simulation of a HPGe detector with PHITS

Gamma ray registration efficiency simulation of a HPGe detector with PHITS

A feasibility study of the measurement of kaonic lead X-rays at DA[formula omitted]NE for the precise determination of the charged kaon mass

An HPGe detector equipped with a transistor reset preamplifier and readout with a CAEN DT5781 fast pulse digitizer was employed in the measurement of X-rays from kaonic lead at the DAΦNE e+e− collider at the Laboratori Nazionali di Frascati of INFN. A thin scintillator in front of a lead target was used to select kaons impinging on it and to form the trigger for the HPGe detector. We present the results of the kaonic lead feasibility measurement, where we show that the resolution of the HPGe detector in regular beam conditions remains the same as that without the beam and that a satisfactory background reduction can be achieved. This measurement serves as a test bed for future dedicated kaonic X-rays measurements for the more precise determination of the charged kaon mass.

Production and evaluation of the polyester composites containing pyrite and niobium diboride for radiation protection

The presented study focused on investigating the radiation shielding properties of polyester/pyrite/niobium diboride (FeSNbB) composites. Various gamma-ray shielding parameters were evaluated with help of a HPGe detector system. Theoretical and simulation results are further evaluated by WinXCOM, GEANT4 and FLUKA codes, and the obtained results are compared with experimental values in the energy region 59.5 keV–1332.5 keV. The prepared samples are additionally evaluated using kerma relative to air values and Exposure build-up factors. Then, for the evaluation of neutron radiation shielding, effective removal cross sections for fast neutrons were determined for FeSNbB composites. Electron attenuation efficiency (AE%) for the produced composites was assessed across the energy spectrum of 4 MeV–18 MeV, utilizing experimental data from a Linac machine and theoretical predictions from Eclipse TPS. The results were found to be compatible with each other. FeSNbB50 has the best shielding properties among the studied composites.

New capabilities of the PAT plutonium analysis program

The Plutonium Attribute Test (PAT) is a software program originally developed for determining the category of a plutonium sample. The premise for its development was that, to assign Pu samples to particular categories, it is not necessary to determine the abundance of all its isotopes. Rather, it is sufficient to determine only 239Pu abundance, which is universally used to establish a category assignment, i.e., >90 wt% 239Pu is low burnup (LBPu), <70 wt% is high burnup (HBPu), and the abundances in between could be considered medium burnup (MBPu) plutonium grade. In contrast to previous Pu isotopic analysis programs which analyse spectra taken with HPGe detectors, the algorithms developed in PAT analyses use spectra taken with medium resolution detectors such as LaBr3(Ce) and CZT detectors. As demonstrated by initial tests, PAT was found capable of not only assigning the material category, but also accurately determining 239Pu abundance, with several per cent typical relative combined standard uncertainty. Furthermore, an advanced algorithm (A-PAT) was added to allow full isotopic characterization of samples. This paper presents further enhancements of the PAT/A-PAT algorithms towards analysis of heavily shielded samples, samples with varied size and age, as well as mixed oxide (MOX) materials.

Radiation doses assessment and radon exhalation rate from the soils of Albyda area, Yemen

This work focuses on evaluating the potential health hazards posed by natural radionuclides in soil samples collected from 20 different sites in the Albyda area, Yemen. The activity concentrations of 226Ra, 232Th and 40K and radon exhalation rates in the soil samples were investigated. Alpha GUARD detector was used to estimate 222Rn concentration, while activity levels for natural radionuclides were measured by HPGe detector. The average values obtained for 226Ra, 232Th, and 40K were 27.60 ± 2.40 Bq/kg, 35.07 ± 2.45 Bq/kg, and 544.71 ± 48 Bq/kg, respectively, and for 222Rn concentrations were 135 ± 15 Bq/m3. Our findings show that the concentrations of radionuclides were within the limits of the world average established by UNSCEAR, except the concentrations of 40K, which was slightly higher than the world average (420 Bq/kg), while the average 222Rn concentration was lower than the ICRP reference level of 300 Bq/m3, and the average area exhalation rate 3.46 × 10−5 Bq m−2 s−1 was lower than the UNSCEAR world average of 0.016 Bq m−2 s−1. Therefore, the soil in this study does not pose any radiological hazard to the population due to the harmful effects of ionizing radiation. The results of the current study highlight the potential health hazard posed by radon and radioactivity levels in the soil samples from Albyda area, Yemen, which will help to increase awareness of the radiological hazard and the data could also be used as a reference for future research on radioactivity mapping in the study area.

Development of a charged particle-[formula omitted] coincidence system for nuclear structure and reaction studies at TIFR

A new detector system for measurements of charged particles and γ-rays in coincidence has been developed at TIFR Mumbai, by coupling an annular double-sided segmented Si detector with an array of Compton-suppressed clover HPGe detectors. Digital data acquisition system has been configured for the setup, which has been calibrated and tested using the 229Th radioactive source that emits α-particles along with γ-rays. The functionality and performance of the coincidence apparatus for Doppler correction of γ-transitions emitted during the in-flight de-excitation of the projectile and the target in the 30Si + 197Au Coulomb excitation experiment have been demonstrated.

A study on the interaction parameters of charged and uncharged radiation types with some indoor plants

This study investigates how gamma rays, neutrons, and electrons interact with five commonly found indoor plants: Spathiphyllum wallisii (SW), Ficus elastica (FE), Dieffenbachia camilla (DC), Schefflera arboricola (SA), and Ficus benjamina (FB). Utilizing experimental measurements (with HPGe detector), Monte Carlo simulations (GEANT4 and FLUKA), and theoretical calculations (ESTAR and WinXCOM), some radiation interaction parameters for gamma rays, fast neutrons, thermal neutrons, and electrons were determined. Secondary particle generation was also analyzed to provide a comprehensive assessment. The determined linear attenuation coefficients with the help of the WinXCOM are 0.1376, 0.1662, 0.1385, 0.1651 and 0.1698 cm-1 for SW, FE, DC, SA and FB, respectively. The calculated total macroscopic cross sections for indoor plants in the same sample order are 2.0290, 2.0350, 2.0285, 2.0363 and 2.0362 cm-1. Among the investigated plants, FB exhibited the highest gamma ray interaction, while SA and FB showed superior interaction against fast neutrons compared to SW and DC. The findings reveal significant variations in interaction effectiveness and secondary radiation production across these plants, offering valuable insights for radiation safety and environmental health evaluations.

Radioactivity Levels, Spatial Distribution, and Radiological Risk Assessment of 226Ra, 228Ra, 40K, and 3H in Water Samples from Dhaka City and Savar, Bangladesh.

This investigation was conducted to measure the radioactivity levels of 226Ra, 228Ra, 40K, and 3H in the 13 most popular branded bottled mineral water (BMW), 12 groundwater sources consumed in Dhaka city, Bangladesh, and six water samples collected from the nuclear object site at Savar, adjacent to Dhaka. The activity of 3H was measured by using a liquid scintillation counter, and a gamma-ray spectrometer with an HPGe detector was used to measure the activity of other radionuclides. The average activity concentrations of 226Ra, 228Ra, 40K, and 3H in BMW samples and groundwater were found to be 1.81 ± 0.43, 1.74 ± 0.40, 43.08 ± 6.23, 2.42 ± 0.16, and 1.61 ± 0.51, 1.69 ± 0.45, 57.42 ± 3.16, and 3.02 ± 0.19 Bq/L, respectively. In addition, the activity concentrations of identified radionuclides in water samples collected from Savar were found to be 1.59 ± 0.43, 1.53 ± 0.50, 99.83 ± 3.05, and 2.95 ± 0.20 Bq/L. With the exception of 3H, the activity concentration and the annual effective dose of 40K, 226Ra, and 228Ra surpassed the acceptable thresholds of the WHO. The combined activity of radium (Rac) also exceeds the USEPA recommended maximum permissible limit of 0.185 Bq/L. The excess lifetime cancer risk results were below the permissible threshold of 10-3 for radiological risks. Groundwater was subjected to an AAS analysis for common metals (Na, Mg, and Ca) and heavy metals (Fe, Cr, Cu, and Pb). The results showed that the heavy metals were below the detection limit. Radionuclide contents in groundwater of Dhaka city were mapped spatially using a GIS technique. Statistical analyses such as one-way ANOVA, one sample t test, and Pearson's correlation analysis were also performed. According to Pearson's correlation analysis, 228Ra is mostly responsible for radiation risk in BMW and groundwater.

Investigation of radioactivity and heavy metal levels in soil samples from neutral and vegetation land of Punjab, India.

In this work, radioactivity investigations of soil samples from neutral and agricultural sites in Punjab (India) have been carried out to study the impact of land use patterns. Analyzing soil samples radiological, mineralogical, and physicochemical attributes has employed state-of-the-art techniques. The mean activity concentration of 238U/226Ra, 232Th, 40K, 235U, and 137Cs, measured using a carbon fiber endcap p-type HPGe detector, in neutral land was observed as 58.03, 83.95, 445.18, 2.83, and 1.16Bqkg-1, respectively. However, in vegetation land, it was found to be 40.07, 64.68, 596.74, 2.26, and 1.90Bqkg-1, respectively. In the detailed activity analysis, radium equivalent (Raeq) radioactivity is in the safe prescribed limit of 370Bqkg-1 for all investigated soil samples. However, the dosimetric investigations revealed that the outdoor absorbed gamma dose rate (96.08 nGy h-1) and consequent annual effective dose rate (0.12mSv y-1) for neutral land and the gamma dose rate (82.46 nGy h-1) and subsequent annual effective dose rate (0.10mSv y-1) for vegetation land marginally exceeded the global average. The soil's physicochemical parameters (pH, EC, and porosity) from both sites were measured, and their correlations with radionuclides were analyzed. Various heavy metals of health concern, namely, chromium (Cr), arsenic (As), copper (Cu), cobalt (Co), cadmium (Cd), lead (Pb), mercury (Hg), selenium (Se), and zinc (Zn), were also evaluated in soil samples using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Pollution Load Index (PLI) and Ecological Risk Index (RI) revealed that vegetation land was more anthropogenically contaminated than neutral land, with maximum contamination from Hg and As.

Characterization of neutron spectrum of polyethylene-moderated AmBe neutron source using a passive single-cylindrical neutron spectrometer

The changes in the neutron spectrum produced by the AmBe neutron source moderated in the polyethylene sphere need to be characterized. A passive single-moderator neutron spectrometer with indium foil activation neutron detector has been developed to characterize the neutron spectrum of an AmBe source inside a polyethylene sphere. The detector response function was calculated using the MCNPX 2.7 program with IRDFF-II nuclear data library. Measurements were conducted by placing the Single-Cylindrical Neutron Spectrometer (SCNS) on the outer surface of the sphere for 5 h. The 116mIn activity due to neutron activation in each indium foil was measured using a gamma spectrometer with an HPGe detector. By identifying the count value at the peak energy of 1294 KeV and considering an HPGe detector efficiency of 3.2% at the foil position 1 mm above the detector surface, the activity of 116mIn was obtained. The activity value of 116mIn from each indium foil was compared with the MCNPX simulation results. The neutron spectrum was unfolded using the UMG 3.3 program with activity data input of 116mIn for each foil and detector response. A neutron spectrum was obtained with a total neutron flux of 634 ± 60 n/cm2·s, consisting of 25% thermal neutrons, 16% epithermal neutrons, and 61% fast neutrons. When compared with the simulation results, the total neutron flux in the spectrum produced by SCNS-In showed only a small difference of 1%. Based on these neutron spectrum measurements, it was determined that placing the AmBe neutron source inside a 15″ diameter PE-sphere will reduce the fast neutron flux by 78%.

A muon beam monitor for the CHNet-MAXI experiment at the RIKEN-RAL laboratory

The CHNet-MAXI experiment (Muonic Atom X-ray and prompt gamma spectroscopy for Isotopic analysis for cultural heritage) is an INFN Cultural Heritage program funded by Scientific Commission V, aiming at selecting the best figures of merit in the isotopic analysis of lead by means of muonic atom emission. The experiment will be deployed at RIKEN-RAL facility ISIS-STFC (UK), providing a pulsed muon beams with momenta between 15 and 90 MeV/c. The CHNet-MAXI apparatus will be mainly based on a 9 HPGe detectors array and innovative scintillator detectors read-out by SiPMs for the detection of the characteristic X and gamma rays emitted by isotopically enriched targets of Pb 204, 206, 207 and 208, after negative muon irradiation at the RIKEN-RAL beamlines. A muon beam hodoscope will be used as a beam x/y profiler and as a beam intensity monitor. This detector has been designed to provide a few mm spacial resolution, and it is based on 3 mm thick scintillating fibers, each read-out by a single SiPM at one edge. The setup is meant to be portable thanks to desktop HV and innovative open-FPGA DAQ modules. All the phases of the design, assembly, and testing of the CHNet-MAXI hodoscope are illustrated. Finally, first operation tests of this new beam monitor are shown.

Background radioactivity level estimation and passive shield optimization using adjoint Monte Carlo method

The current study proposes a procedure to estimate the activity concentration of natural radionuclides and to optimize passive shielding solutions for HPGe detectors using adjoint Monte Carlo (MC) simulation technique of Geant4 for the first time. The background spectrum is acquired for 1.56 × 106 s using an HPGe detector model (GC3020), set inside a shielding solution, during 2021–2022 to estimate the activity concentration of natural radionuclides inside the shielding. While, a background spectrum for 65,000 s is acquired with shielding removed to estimate the concentration of natural radionuclides in the building materials of the laboratory. The detector design used in the simulations is validated by comparing computed and measured Full Energy Peak Efficiency (FEPE) for point sources 241Am, 152Eu, 137Cs, 133Ba, and 60Co. Adjoint MC simulations are used to compute the activity concentration of natural radionuclides assuming an isotropic distribution. The activity concentration of 40K, 226Ra and 232Th in the building material is found to be 524 ± 140, 83 ± 20 and 65 ± 18 Bqkg−1, respectively. The computed values are found in good agreement with the published data. The natural radioactivity levels of 40K, 226Ra and 232Th measured in lead shielding are 155.7 ± 0.1 mBqkg−1, 24 ± 13 mBqkg−1 and 33 ± 17 mBqkg−1 respectively. The radiological risks arising due to natural radioactivity is assessed by calculating radium equivalent activity (Raeq), indoor radiation hazard index (Hin) and annual effective dose equivalent. All the radiological parameters are found below their permissible limits and building materials may be considered radiologically safe. The optimal lead shield thickness for the detector is determined to be 12 cm, resulting in reduction of background signal by two orders of magnitude compared to an unshielded detector. The adjoint MC simulations in Geant4 are 103-104 times more rapid as compared to normal simulations for shield optimization of HPGe detectors and therefore, are identified as viable computing solution to calculate the activity of the background radiation.

Characterization of Gamma Spectroscopy Setup, Efficiency Calibration of HPGe detector used for Radiological substances

Background: Contamination of radiological substances in environment is one of the most important factors and harmful for living beings if the activity is high enough with long half-life.‘Gamma Spectrometry Setup’ is comparatively better for detection and analysis of gamma radiations in any type of specimens. Initiating the data acquisition setup, it’s essential to calibrate the entire setup for accuracy measurement. Materials and Methods:The main purpose of the research work is to characterize the data acquisition setup using137Cs and 60Co point sources. 137Cs emits γ-rays of 661.66 keV and 60Coemits two different γ-rays; 1173.2 KeV &amp; 1332.5 KeV. Setup standardization is an essential part of any research works. Results: The HPGe detector used with the setup is also good enough for γ-energy detection. Detector efficiency calibration is another major task needed for activity calculation, using gamma energy lines detected in a sample detector efficiency can be calculated. Conclusion: Initiating every research experiment, the setup calibration should be checked for accurate results

Record high counting rate of a non-beam-based positron annihilation age–momentum correlation (AMOC) spectrometer achieved by geometrical optimization of detectors

Positron annihilation age–momentum correlation (AMOC) spectroscopy is not only a critical approach to investigate positronium formation and annihilation, but also a powerful technique for materials science to characterize the chemical environment of pores. However, due to the long measurement time (several days to collect 10 million counts for one sample, at a low coincidence counting rate of approximately 20–40 cps) of a conventional non-beam-based AMOC spectrometer, AMOC technique has been rarely applied. In this work, based on the geometrical simulations of detectors using Geant4 program, we developed a new semi-digital AMOC spectrometer with two start detectors. After systematic optimizations of geometrical configurations of detectors, timebase of digital oscilloscope, and the energy windows of start and stop detectors, this instrument achieved the highest coincidence counting rate for a non-beam-based AMOC spectrometer (∼ 180 cps for a narrow stop energy window of 469–589 keV and the shaping time of HPGe detector at THPGeshaping = 6μs, and ∼ 500 cps for a wide stop energy window of 104–589 keV and THPGeshaping = 2μs). The drastic rise of coincidence counting rate will broaden the applications of AMOC spectrometers in positronium physics and materials characterization in future.

Assessment of soil moisture on radon levels, radon exhalation, natural radioactivity, and radiological risks in offices and laboratories in GAEC

This study investigates the influence of moisture on soil radon exhalation, natural radioactivity in soil, and indoor radon concentrations in offices and laboratories at the Ghana Atomic Energy Commission (GAEC) and their associated radiological risks to workers. Radon exhalation rates were determined using the Sealed Can method. CR-39 SSNTD detectors were used to measure indoor radon concentrations. Gamma spectroscopy using HpGe detector was used to determine the activity concentrations of U-238, Ra-226, Th-232, and K-40 in the soil samples. The results showed mean concentrations of 14.3 ± 2.0 Bq/kg (CI 95%: 10.0–18.0) for U-238, 145.0 ± 10.0 Bq/kg (CI 95%:123.0–167.0) for K-40, 31.5 ± 6.0 Bq/kg (CI 95%: 24.0–39.0) for Th-232, and 15.6 ± 2.0 Bq/kg (CI 95%:14.0–29.0) for Ra-226. The results showed mean surface and mass exhalation rates of 6.9 ± 2.3 × 10−4 Bq/m2/h1 (CI 95%: 5.7 × 10−4 –12.6 × 10−4) and 2.4 ± 0.4 (CI 95%: 1.9–4.2) nBq/kg1/h1 respectively. The findings revealed mean indoor radon concentrations of 93.0 ± 10.0 Bq/m3 (CI 95%: 88.0–98.0), 111.0 ± 12.0 Bq/m3 (CI 95%: 102.0–119.0) and 145.0 ± 13.0 Bq/m3 (CI 95%: 135.0–155.0) in the offices, laboratories, and basements respectively, with laboratories and basements exceeding the WHO reference level of 100 Bq/m3. A strong inverse relationship between moisture levels and exhalation rates (r = −0.8) was observed, leading to a negative correlation (r = −0.3). Between the moisture levels and indoor radon levels. The research findings indicated a mean annual effective dose of 0.6 mSv/yr. (CI 95%: 0.5–0.6) to the workers, which is well below occupational and public dose limits. The lung cancer cases of workers were computed which ranged from 0.9 × 10−8 to 1.2 × 10−8 cases per million people per year, which is less than the limit range of 170–230 per million people per year recommended by ICRP but remaining with safe radiological limits for workers. This study identified moderate radon exposure risks at the GAEC, exceeding the WHO recommendation. The correlation and trend analysis demonstrate strong relationships between moisture, exhalation rates, radium, and indoor radon.

Integration of beta counting system with ORION-DSP coupled to NaI(Tl) detector-a comparative study with an HPGe detector.

The integration of the ORION digital signal processing-based MCA system coupled with a 3″ × 3″ NaI(Tl) detector assembly with a GM detector for counting beta (β) has eliminated the need for a standalone β-γ method in which U3O8 is determined by gross β and gross γ counting. Uraniferous and mixed U-Th samples were taken up for study and compared with the results obtained from Canberra p-type coaxial high resolution gamma ray spectrometry detector. In uraniferous samples, U3O8 values obtained are within ±10%, whereas in the case of mixed U-Th samples, U3O8 values are within ±15%. Regression graphs drawn between the outcomes from the two analytical systems indicate R2>0.95 for Ra(eU3O8) and ThO2. In uraniferous samples, the R2 value for U3O8 was found to be > 0.99, but in mixed U-Th samples, it is 0.92. The closeness of agreement between the results obtained from two methods at various concentrations over the analytical range shows that the integrated system is suitable for the quantitative determination of eU3O8, U3O8, Ra(eU3O8), ThO2 and K in geological rock samples.

Low and high-resolution gamma-ray spectroscopy for the characterization of uranium contamination

Decommissioning is the last step in the life cycle of a nuclear facility. After the evacuation of the facility components, the remaining structures such as concrete walls and floors must be controlled to ensure that no residual contamination remains. As it is a costly and time consuming activity, CEA develops fast measurement methods allowing a complete scanning of very large areas (hundreds of thousands of square meters) in legacy uranium enrichment plants based on gas diffusion, at Pierrelatte nuclear site, France. After fast alpha and beta measurements, HPGe and NaI gamma-spectroscopy detectors are used to characterize more precisely uranium contamination. HPGe has excellent energy resolution but requires very long acquisition times. On the contrary, NaI(Tl) detectors enable rapid measurement, but extracting the contamination signal from the natural background is difficult due to their low resolution. Using an innovative approach based on energy bands of the NaI spectra, contamination activity and enrichment are consistent with that measured with HPGe but in only 15 min vs. 65 h, and with a sufficiently low relative uncertainty of about 15 % and 20 %, respectively, on activity and enrichment. Large area NaI(Tl) detectors will allow cost-effective scanning of the Gaseous Diffusion Plant (UDG) nuclear site (hundreds of thousands of squared meters) within practical times, in complement to alpha and beta contamination detectors.