High Radiation Areas Research Articles

Bayesian approach for inferring two-dimensional location of a radioactive material using distributed detectors

Our research team developed a small probe to measure and analyze the environmental radiation at the sampling site for nuclear inspection. The location and activity of the radiation source are estimated using data obtained from multiple probes. In this study, Bayesian inference was applied to infer the location and activity of the radiation source. The experiments were conducted under the one-source and two-source conditions, with the same area, distribution of the probes, and measurement time. To quantitatively express how well the inferred coordinates represent the actual coordinates, the coefficient of determination was calculated. Root Mean Square Error was used to express the errors in the inferred data. In addition, measurement experiments were conducted in high-radiation areas near the Fukushima Daiichi nuclear power plant. Our model can provide sufficient information for inferring the location of leaked material and evaluating the safety in various environments such as nuclear verification, accidents, or terrorist activities.

External Radiation Dose to the Shore Crab of Chinnavilai, a High Background Natural Radiation Area

The aim of the study was to determine the activity concentration and radiation dose of radionuclides 226Ra, 228Ra & 40K in shore crab Hemigrapsus Sanguineus, in Chinnavilai, Kayakumari district, Tamil Nadu, India. Gamma spectrometry is used for determine activity concentration and radiation dose of radionuclides (226Ra, 228Ra & 40K.). The total dose values due to both internal and external contributions by all three studied radionuclides fell between 26.51 and 53.19 µGy/day. These values are far below the dose limits (10 mGy/day) prescribed for aquatic animals by the US Department of Energy (2002) and hence the animals are safe, radiologically as far as these radionuclides are concerned. The minimum internal dose for 228Ra in shore crab 0.30 and the external dose 16.42. The total dose for 228Ra in shore crab 16.72. The maximum internal dose for 228Ra in shore crab 0.64 and the external dose 30.03. The total dose for 228Ra in shore crab 30.67.

A passive single-cylindrical neutron spectrometer for photoneutron spectrometry in 10 MV Elekta Precise Linac head

Measuring the neutron spectrum on the Linac head using a passive type neutron detector is relatively easier than an active type detector because it does not require the involvement of operators who work in a high radiation area. Neutron spectrum measurements with passive foil activation neutron detectors in a single-moderator are more practical and easier than multi-foil techniques. This technique is quite simple, easy to make, low cost, and the measurement time is relatively short. This spectrometer is designed by placing seven passive Au detectors at varying depths in a single-cylindrical moderator. The response function for each detector is calculated by MCNPX 2.7 program and used ENDF7 as a nuclear data library. Detector foil activity was measured using a gamma spectrometer, and the neutron spectrum was obtained using the unfolding technique using the UMG 3.3 program. The results of measuring the neutron spectrum measurements have been carried out at a position 10 cm below the head of the Elekta Precise 10 MV Linac was 2.73 × 105 n/cm2·s, where the fast neutron from these results are 4% higher when compared to the simulation results using PHITS.

Natural radionuclides and radiological risk assessment in the stream and river sediments of a high background natural radiation area Kanyakumari, India.

The Kanyakumari coast is known to be a high background natural radiation area due to the placer deposits of heavy minerals such as ilmenite, monazite, and rutile. The Kanyakumari river sediments that could be the source of the elevated amounts of natural radionuclides in the coastal sands have been studied in this paper. The activity concentrations of primordial radionuclides 226Ra, 232Th, and 40K were determined using high-purity germanium (HPGe) gamma-ray spectrometry. The mean activity concentrations of 226Ra, 232Th, and 40K were found to be 75Bqkg-1, 565Bqkg-1, and 360Bqkg-1, respectively. The mean absorbed dose rate was 395 nGy h-1. Radiological hazard parameters were studied and compared with the world average values. The contribution of 232Th to the total dose rate was found to be higher than that of the two other radionuclides. The high mean ratio of 232Th/226Ra suggested an enrichment of 232Th and the occurrence of 226Ra leaching due to an oxidizing environment. Principal component analysis (PCA) was carried out for the radionuclides in order to discriminate the source of the sediments. This study provides new insights into the distribution of natural radionuclides in sediments of rivers and streams.

Distribution of naturally occurring radionuclides and gamma dose rate assessment in the soils of high background natural radiation area Odisha, India.

A study on the activity concentration of primordial radionuclides 226Ra, 232Th and 40K was carried out on the surface soil samples collected from the coastal villages between Chhatrapur and Gopalpur regions of high background natural radiation area Odisha, India, using high purity germanium gamma spectroscopy. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 231, 1692 and 250Bq/kg, respectively. The total mean absorbed dose owing to the presence of 226Ra, 232Th and 40K was 1139nGy/h. The mean annual effective dose was found to be 1397μSv/y and higher than the UNSCEAR average value 70μSv/y.

Estimation of radiation dose due to thoron and progeny inhalation in high background natural radiation area of Odisha, India

Abstract Results of the preliminary measurements of indoor radon, thoron and progeny concentrations showed very high values of thoron concentrations in the eastern coastal region of Odisha, India. Therefore, measurements of thoron and its progeny concentrations were extended to a larger number of houses in this area for the assessment of the radiation dose received by the public. The measured values of thoron concentrations were used for the calculation of annual effective doses. The estimated values of the annual effective dose due to thoron exposure were observed in the range of 0.2–14.7 mSv. The estimated radiation doses responsible for thoron exposure were observed considerably high in the region. The results obtained are compared with those obtained in other studies performed so far in the study area and a review of different studies involving different measurement techniques is presented in the paper. The results of this study support the preliminary studies showing high values of thoron levels in the study area.

Optimization of Personnel Work Paths During Decommissioning of Nuclear Facilities

During the decommissioning process of nuclear facilities, workers are exposed to radiation and face the risk of exceeding safe dose limits. Ensuring the safety of personnel requires not only enhancing radiation protection measures but also optimizing work paths to minimize exposure time and avoid high-radiation areas. This paper proposes a nested optimization algorithm that combines an ant colony optimization (ACO) with an improved A* algorithm for the decommissioning of a nonradiation source. The algorithm aims to minimize the total radiation dose and transforms the original path optimization problem into an equivalent traveling salesperson problem. The improved A* algorithm is employed in the inner layer to calculate the path with the lowest radiation dose for any given sales order. The ACO operates in the outer layer to determine a set of optimal working paths that traverse all target points. The provided solution example demonstrates that the proposed path optimization algorithm effectively integrates the radiation field and obstacles. It successfully identifies a sequence for dismantling with the lowest dose and corresponding optimal work path while ensuring the completion of the dismantling task. These findings are expected to offer valuable insights for optimizing personnel work paths during the subsequent decommissioning process of nuclear facilities.

Progress with the regulation of radiation safety during recovery and removal of spent nuclear fuel from the site for temporary storage at Andreeva Bay on the Kola Peninsula.

In the 1960s, a shore technical base (STB) was established at Andreeva Bay on the Kola Peninsula, in northwest Russia. The STB maintained nuclear submarines and the nuclear icebreaker fleet, receiving and storing fresh and spent nuclear fuel (SNF) as well as solid and liquid radioactive waste (RW). It was subsequently re-designated as a site for temporary storage (STS) for SNF and RW. Over time, the SNF storage facilities partly lost their containment functions, leading to radioactive contamination of workshops and the site above permitted values. The technological and engineering infrastructure at the site was also significantly degraded as well as the condition of the stored SNF. At present, the STS Andreeva Bay facility is under decommissioning. This paper describes progress with the creation of safe working measures for workers involved in site remediation and SNF recovery operations, including the determination of safe shift times in high radiation areas, as part of overall optimization of safety. Results are presented for the successful application of these measures in the period 2019-2021, during which time significant SNF recovery and removal operations were completed without incident. Significant important experience has been gained to support safe removal of remaining SNF, including the most hazardous degraded fuel, as well as recovery of other higher level RW and decommissioning of the old storage buildings and structures.

“Radiation to Materials” at CERN

Irradiation tests are continuously needed at the European Organization for Nuclear Research (CERN), to experimentally assess the radiation tolerance of commercial non-metallic materials for use in high-radiation areas. The ’Radiation to Materials’ R2M activity organizes such tests and provides expertise in the interpretation of results, for the design and upgrade of devices absorbing critical doses during their lifetime. The various activities covered by the R2M are presented. Up to ten irradiation tests per year are organized in external <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co facilities, in which samples absorb up to several MGy of gamma dose at dose rates in the kGy/h range. Cables, O-rings, lubricants, glues, optical materials, and insulators are examples of possible tested materials. In parallel, selected samples are irradiated in a mixed neutron and gamma irradiation station built close to the Neutron Time-Of-Flight facility. Dedicated research studies, mainly focused on oil, greases and elastomeric O-rings, are being performed to deepen the understanding of radiation effects in these critical materials. As an example, the mechanical and structural characterization of two elastomeric EPDM-based commercial materials irradiated in gamma radiation up to 3 MGy of dose is presented.

Pointing stabilization of 140 mJ, 10 Hz UV laser for Laser-Assisted Charge Exchange

This paper details a laser beam delivery and pointing stabilization system designed for the Laser-Assisted Charge Exchange (LACE) experiment at the Spallation Neutron Source (SNS) accelerator. The UV (355 nm) laser beam of 140 mJ pulses at 10 Hz must be transported over 65 m through a retrofitted laser transport line in a high-radiation area of the accelerator, causing the alignment of the beam to jitter and drift significantly on timescales of 0.1–1 s and >1 min, respectively, due to thermal effects and other disturbances. The laser pointing stabilization system is based on a novel technique which uses active feedback between CMOS cameras and a piezoelectric steering mirror controlled by feedback software to make corrections to the horizontal angle and vertical position of the laser beam at 10 Hz. Low frequency drift is easily controlled, and the long-term stability is limited by the amplitude of high frequency components of the spectrum near the Nyquist limit (5 Hz). With feedback turned on, the root-mean-square (RMS) deviations of the horizontal angle and vertical position over 20 min fell from 314 to 157 μrad and 309 to 167μm, respectively, which is below the pulse-to-pulse jitter at 10 Hz of 189 μrad RMS and 180μm RMS.

Distribution of natural radionuclides in NORM samples from North Abu Rusheid area, Egypt

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. 238U and 232Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and 40K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of 238U, 232Th and 40K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of 238U, 232Th and 40K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials.

Rare Earth Elements Geochemistry and 234U/238U, 235U/238U Isotope Ratios of the Kanyakumari Beach Placer Deposits: Occurrence and Provenance

Geochemical studies of rare earth elements (REEs) as well as major and trace elements were conducted on the beach placer sands from the Kanyakumari coastal region, a well-known high background natural radiation area (HBNRA). For the first time, uranium isotope ratios (234U/238U and 235U/238U) were determined in the study area to investigate the provenance and leaching of U from the beach sands. Inductively coupled plasma mass spectrometry was used for the measurement of REEs and trace elements whereas thermal ionization mass spectrometry (TIMS) was used for the measurement of U isotope ratios. ∑REEs were found to be in the range of 778.93 to 15,007. 54 µg/g, whereas ∑Light REEs were in the range of 770.58 to 14,860.80 µg/g and ∑Heavy REEs varied from 8.35 to 146.74 µg/g. The enrichment factor showed the LREEs Th and U were extremely enriched in the Kanyakumari beach placer sands. The 235U/238U isotope ratios were similar to the natural terrestrial ratio value. The 234U/238U activity ratio varied from 0.995 to 1.071, and showed the prevailing secular equilibrium among them. The δ238U results could, to some extent, explain the U fractionation and source.

Chronic exposure effect study on Ramsar high background natural radiation areas (HBNRAs) residents using micronucleus assay

تأثیر پرتوگیری مزمن بر ساکنین مناطق با پرتوزایی طبیعی بالا در شهر رامسر، با استفاده از روش سیتوژنتیک سنجش هستک­های متوقف شده در مرحله سیتوکینز و مقایسه­ی نتایج میان دو گروه مورد مطالعه و کنترل، مورد بررسی قرار گرفت. نتایج نشان داد اختلاف معنی­داری (001/0< P) در میانگین فرکانس هستک­های شمارش شده در لنفوسیت­های خون محیطی گروه مورد مطالعه (ساکن در منطقه­ی با پرتوزایی طبیعی بالای شهر رامسر) و گروه کنترل (ساکن در شهر تنکابن) وجود دارد. هم­چنین، بعد از پرتودهی نمونه­ها، گروه کنترل، افزایش بیش­تری را در فرکانس هستک­ها نسبت به گروه مورد مطالعه نشان داد و این امر، شاهدی بر وجود پدیده پاسخ تطبیقی پرتوی، در ساکنین مناطق با پرتوزایی طبیعی بالا در شهر رامسر می­باشد. همبستگی میان فرکانس هستک­ها و سن، در گروه کنترل بیش­تر از گروه مورد مطالعه مشاهده شد.

Design of optical transmission line of ITER poloidal polarimeter

ITER Poloidal Polarimeter is laser-aided diagnostics that measures the change of polarization of injected far-infrared laser beam in order to identify plasma current profile. PoPola consists of thirteen measurement chords, and each chord is comprised of a set of optical components. This study shows the design of optics in the ITER vacuum vessel and those in high radiation area outside the vacuum vessel. The design takes into account zero-offset configuration, the minimization of the neutron streaming, remote alignment, accessibility, manufacturability and radiation hardness. The laser power loss due to vignetting loss and absorption is evaluated, and the signal-to-noise ratio at a detector is estimated at 50,000. This study evaluates the acceptable errors of manufacturing and assembly of the optical transmission line on the condition that the demonstrated alignment method using the two steering mirrors outside the vacuum vessel is applied. The evaluation results show that the medium tolerance class of ISO 2768 is basically enough for manufacturing ITER poloidal polarimeter. Only for assembling the in-vessel mirrors to the mirror module, the mirror angles need to be carefully adjusted with accuracy of 0.1° Finally, radiation hardness of a steering mirror is presented. The steering mirror consists of an angle sensor and a piezo actuator. The angle sensors are developed by the authors and free from semiconductor and soft resin. The prototype test results show that angle sensor can measure the mirror angle in the range of ±2.3° with accuracy of 0.37%. As for the piezo actuator, the irradiation test was carried out. The test results show that the piezo actuator is able to operate after the neutron fluence of 3.5 × 1015 n/cm2 and the gamma dose of 0.99 MGy.

Upgraded Cherenkov time-of-flight detector for the AFP project.

We present the results of our performance studies of the upgraded Cherenkov time-of-flight (ToF) detector for the AFP (ATLAS Forward Proton) project. The latest version consists of solid L-shaped fused silica bars, new customized ALD-coated micro-channel plate photomultipliers (MCP-PMTs) miniPlanacon XPM85112-S-R2D2 with an extended lifetime which operate at low gains (order of 103), and an updated construction. The improvements were aimed to increase the efficiency, the lifetime as well as the radiation hardness of the detector which has been designed to operate in high radiation areas (above 400 kGy/year). The detector was finally tested at the CERN-SPS test-beam facility (120 GeV π+ particles) in August 2021 prior to its installation at the Large Hadron Collider (LHC) at CERN. Measurements proved the detector kept its inner timing resolution of 20 ps despite the rather low gain of its photodetector and reduced optical throughput caused by inevitable changes in the detector geometry.

In-beam superfluid-helium ultracold neutron source for the ESS

This paper discusses design principles and possible performances of an “in-beam” ultracold neutron (UCN) source for the European Spallation Source (ESS). The key components of the proposed neutron delivery system are nested-mirror optics (NMO), which image the bright neutron emission surface of the large liquid-deuterium moderator, studied within the HighNESS project, onto a remotely located superfluid-helium converter. Bandpass supermirrors, with optional polarization capability, enable the selective transport of those neutrons that are most effective for UCN production, exploiting the single-phonon conversion process that is possible for neutrons having wavelengths within a narrow range centered on 8.9 A ˚. NMO are capable of extracting and refocusing neutrons with small transport losses under the large solid angle available at the ESS Large Beam Port (LBP), allowing the converter to be placed far away from the high-radiation area in the ESS shielding bunker, where the source stays accessible for trouble-shooting while facilitating a low-background environment for nearby UCN experiments. Various configurations of the beam and converter are possible, including a large-volume converter – with or without a magnetic reflector – for a large total UCN production rate, or a beam focused onto a small converter for highest possible UCN density. The source performances estimated by first simulations of a baseline version presented in this paper, including a saturated UCN density on the order of 10 5 cm − 3 , motivate further study and the development of NMO beyond the first prototypes that have been recently investigated experimentally.

Study on the impact of partition photovoltaic electrochromic windows on building lighting environment and energy saving

Electrochromic (EC) window can adjust the indoor lighting environment, but its control strategy will greatly affect its performance and bring additional energy consumption. Therefore, this research integrates photovoltaic (PV) shading technology and designs an optimized partition photovoltaic electrochromic (PV-EC) window, which mainly includes the PV area covered with crystalline silicon cells, the EC area with electrochromic glass and the transparent area used to ensure lighting environment in cloudy days. Because each area can be controlled independently, under different control strategies, the system can realize the accurate regulation of lighting environment. Moreover, the system can use the energy generated by PV modules to be self-sufficient on energy and can also use PV modules as sunshade device. A partition PV-EC window building internal lighting environment test rig was built to explore the impact of partition PV-EC window on lighting environment under different control strategies. Among four strategies, the useful daylighting illuminance of illuminance strategy is the largest and reaches 79.88 %. Therefore, from the perspective of lighting environment, illuminance strategy should be chosen for partition PV-EC windows. On the grounds of the building energy simulation results, radiation strategy can save energy by 13.71 % compared with that of ordinary Low-E windows in high radiation areas. Therefore, from the perspective of building energy consumption, radiation strategy should be chosen for partition PV-EC windows. The above results show that partition PV-EC windows can be beneficial to create a better lighting environment without bringing additional energy burden and has a certain promotion value.

Solution-processed CZTS thin films and its simulation study for solar cell applications with ZnTe as the buffer layer.

Using zinc tellurium (ZnTe) as the buffer layer in the Cu2ZnSnS4 (CZTS)-based solar cells showed an improvement in overall efficiency. ZnTe is investigated as an alternative to replace the conventional toxic Cd-contained buffer layers. It may also reduce the overall cost of these cells as both layers (ZnTe and CZTS) have eco-friendly and earth-abundant constituents. The sol-gel spin coating method is used for the deposition of CZTS thin films on the corning glass substrates. The X-ray diffraction studies showed the peaks corresponding to (112), (200), (220), and (312) planes which confirmed the formation of the essential kesterite phase. The optical band gap of the deposited films was found at around 1.45eV by the UV-visible-NIR spectrophotometer. The optimum thickness of the absorber layer (CZTS) and buffer layer (ZnTe) was investigated based on the performance of the ZnO:Al/ZnO/ZnTe/CZTS/Mo cell structure by using the AMPS-1D simulation tool. In contrast, the tool was molded by the experimentally investigated data for the constituent materials of the cell structure. The solar cells' efficiency was increased by 23.47% at 2500nm and 50nm thickness of the CZTS and ZnTe layers, respectively. In addition, it was analyzed and found that the current density value showed an improvement with operating temperature as it is one of the requirements in the high solar radiation areas where the temperature even rises more than 50°C in the summer.

Dietary exposure of radionuclides and heavy metals in adult residents in a high background natural radiation area using duplicate diet method

Intake of radionuclides and heavy metals through food consumption is one of the important pathways for long-term health considerations. In this paper, the dietary exposure to radionuclides (210Pb, 210Po, 226Ra, 228Ra, 40K, 137Cs and 129I) and heavy metals (As, Hg, Pb, Cd and U) of adult residents in the high background natural radiation area (HBNRA) in Yangjiang, China, was comprehensively assessed using duplicate diet method. The estimated effective dose received by the inhabitants in HBNRA from ingestion of radionuclides was 0.33 mSv/y, and the associated lifetime cancer risk was 1.1 × 10–3. Both the dose and cancer risk to humans were at the acceptable range, and showed no difference between the HBNRA and the control area. With respect to heavy metals, the estimated daily intake of heavy metals (DIM) values for As, Hg, Pb, Cd and U in HBNRA were 0.47, 0.03, 15.0, 0.26 and 0.04 μg/kg bw/d, respectively, and the corresponding target hazard quotient (THQ) were 1.58, 0.09, 3.7, 2.56, 0.18. The DIM and THQ of Cd and U in HBNRA were similar to the control area, but the DIM and THQ of Pb were much higher than the corresponding values of 0.39 and 0.03 in the control area. The hazard index (HI) value of heavy metals in HBNRA was almost twice that of the control area. This suggests that the inhabitants in the HBNRA may have a health risk associated with the heavy metals.

Evaluation of the radiological dose due to 210Po in commercial clupeid fish collected in the near-shore environment of the high background natural radiation area (HBNRA) on the southwest coast of India

In this study, we quantified the tissue concentration of 210 Po in a variety of commercial sardine fish species of the family Clupeidae from an area of high background natural radiation area on the southwest coast of India. The smooth belly sardine Amblygaster leiogaster had the lowest 210 Po concentration in its muscle (45.6 ± 7.9 Bq kg −1 fresh), while the goldstripe sardine Sardinella gibbosa had the highest (103.4 ± 10.1 Bq kg −1 fresh). The Annual Committed Effective Dose (ACED) of fried sardine and sardine curry were 134.3–304.3 μSv y −1 and 226.6–513.5 μSv y −1 , respectively. Of the 210 Po loss, 20 % was due to frying and 10 % to preparing sardine curry. The effective dose was found to be globally comparable and well below the world limit. Consumption of sardines containing 210 Po would not pose a health hazard to the residents of Manavalakurchi. • 210 Po quantified in the muscle tissue of sardine fishes. • The study carried out in the high background natural radiation area. • The annual committed effective dose was computed using raw and cooked sardines. • The effective internal dose does not impact much to the residents.