Cemented Containers Radiological Data From a Disused Uranium Mine Low-Level Waste Repository: A Calculated-Experiment Cross-Check for Data Verification and Validation

2003 ◽  
Author(s):  
D. G. Cepraga ◽  
G. Cambi ◽  
M. Frisoni ◽  
D. Ene
Keyword(s):  
Experimental Data ◽  
Dose Rate ◽  
Measured Data ◽  
Radioactive Material ◽  
Uranium Mine ◽  
Low Level ◽  
Dose Rates ◽  
Waste Repository ◽  
Central Plan ◽  
Decay Gamma

Code validation problems involve calculation of experiments and a comparison experiment-calculation. Experimental data and physical properties of these systems are used to determine the range of applicability of the validation. Once a sequence-code of calculations has been validated, it has to be underlined that the comparison experimental-calculated results involving “complex systems” or “complex experimental measures” permits also a bi-lateral cross-check between the calculation scheme and the experimental procedures. The results of the testing and the validation effort related to the collection of information and measured data and the comparison between code results with experimental data coming from a “low-level waste” repository are presented in this paper. The Baita-Bihor repository, sited into former disused uranium mine in Transylvania, has been considered as the source of experimental data. The study was developed through the following steps: a) collection and processing of measured data (radioactivity content and dose rate), from the cemented containers of the Baita-Bihor repository; b) decay gamma source calculation by the ANITA-2000 code package (the input data for the calculations are the measured isotope activities for each container); c) decay gamma transport calculation by the SCALENEA-1 shielding Sn sequence approach (Nitawl-Xsdrnpm-Xsdose modules of the Scale 4.4a code system, using the Vitenea-J library, based on FENDL/E-2 data) to obtain dose rates on the surfaces and at various points outside the containers; d) comparison experimental-calculated dose rates, taking into account also the measurement uncertainties. The new version of the ANITA-2000 activation code package used makes possible to assess the behaviour of irradiated materials independently from the knowledge of the irradiation scenario but using only data on the isotope radioactive material composition. Radioactive waste disposed of at Baita Bihor repository consists of worn reactor parts, resins and filters, packing materials, mop heads, protective clothing, temporary floor coverings and tools, the sources normally generated during the day-to-day operation of research reactors, the remediation-treatment stations and the medicine and biological activities. The low and intermediate wastes are prepared for shipping and disposal in the treatment stations by confining them in a cement matrix inside 220 litre metallic drums. Each container consists of an iron cladding filled by concrete Portland. Radioisotope composition and radioactivity distributions inside the drum are measured. The gamma spectroscopy has been used for. The calibration technique was based on the assumption of a uniform distribution of the source activity in the drum and also of a uniform sample matrix. Dose rate measurements are done continuously, circularly, in the central plan on the surface of the drum and 1 m from the surface, in the air. A “stuffing factor” model has been adopted to simulate, for the calculation, the spatial distribution of the gamma sources in the concrete region. In order to guarantee a complete Quality Assurance for codes and procedures, a simulation of the radioactive containers to evaluate the dose rates was done also by using the Monte Carlo MCNP-4C code. Its calculation results are in a very good agreement with those obtained by the Sn approach (discrepancies are around 2%, using the spherical approximation).

DOSE RATE IN A DEACTIVATED URANIUM MINE

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
Wagner De Souza Pereira ◽  
Alphonse Kelecom ◽  
Ademir Xavier Da Silva ◽  
José Marquez Lopes ◽  
Alessander Sá Do Carmo ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Dose Rate ◽  
Electronic Monitoring ◽  
Limit Of Detection ◽  
Monitoring Program ◽  
Radioactive Material ◽  
Uranium Mine ◽  
Treatment Unit ◽  
Thermoluminescence Dosimetry ◽  
Area Monitoring

The Ore Treatment Unit is a deactivated uranium mine and milling situated in Caldas, MG, BR. Although disabled, there are still areas considered controlled and supervised from the radiological point of view. In these areas, it is necessary to keep an occupational monitoring program to ensure the workers' safety and to prevent the dispersion of radioactive material. For area monitoring, the dose rate, in µSv∙h-1, was measured with Geiger Müller (GM) area monitors or personal electronic monitors type GM and thermoluminescence dosimetry (TLD), in mSv∙month-1, along the years 2013 to 2016. For area monitoring, 577 samples were recorded; for personal dosimeters monitoring, 2,656; and for TLD monitoring type, 5,657. The area monitoring showed a mean dose rate of 6.42 µSv∙h-1 associated to a standard deviation of 48 µSv∙h-1 with a maximum recorded value of 685 µSv∙h-1. 96 % of the samples were below the derived limit per hour for workers (10 µSv∙h-1). For the personal electronic monitoring, the average of the data sampled was 15.86 µSv∙h-1, associated to a standard deviation of 61.74 µSv∙h-1. 80 % of the samples were below the derived limit and the maximum recorded was 1,220 µSv∙h-1. Finally, the TLD showed a mean of 0.01 mSv∙h-1 (TLD detection limit is 0.2 mSv∙month-1 equivalent to 0.28 µSv∙h-1), associated to a standard deviation of 0.08 mSv∙h-1. 98% of the registered values were below 0.2 mSv∙month-1 and less than 2 % of the measurements had values above the limit of detection. The samples show areas with low risk of external exposure, as can be seen by the TLD evaluation. Specific areas with greater risk of contamination have already been identified, as well as operations at higher risks. In these cases, the use of the individual electronic dosimeter is justified for a more effective monitoring. Radioprotection identified all risks and was able to extend individual electronic monitoring to all risk operations, even with the use of the TLD.

Measurements of the High Dose Rate Profiles Inside a Shutdown CANDU® Reactor

2012 ◽  
Vol 1 (1) ◽  
pp. 27-34
Author(s):  
C. Jewett ◽  
J. Chow ◽  
D. Comeau ◽  
G. Jonkmans ◽  
B. Smith ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Dose Rate ◽  
High Dose Rate ◽  
Measured Data ◽  
High Dose ◽  
Dose Rates ◽  
Diode Detector ◽  
Γ Ray ◽  
Rate Profile

The positions of the components of a reactor can change over time, due to radiation damage, sagging, etc. Thus, it is important to determine their positions. To satisfy this requirement of the staff at the Point Lepreau Generating Station, a method to determine the positions of reactor components has been developed and demonstrated. This method combines the use of dose rate measurements and Monte Carlo simulations. It first involves measuring the high γ-ray dose rates as a function of position within a reactor. Then it entails comparing these measurements with Monte Carlo simulations. In order to perform such measurements, a silicon diode detector and a scan drive system have been developed. In 2009, measurements of the γ-ray dose rate profile of the shut down Point Lepreau Generating Station reactor were conducted. By comparing the locations of the local peaks in the dose rate data, it was possible to determine the distances between the steel reactor components. The measured data were then compared with Monte Carlo simulations to determine how precisely one could locate the positions of the adjuster rods. Using this technique, it was found that the retracted adjuster rods were 440 ± 60 mm below their designed positions.

Measurement of ambient dose rates in tantalite mining sites in Oke ̶ Ogun, southwest, Nigeria

2021 ◽  
Vol 20 (2) ◽  
pp. 1-12
Author(s):  
A.E. Ajetunmobi ◽  
S.K. Alausa ◽  
J.O. Coker ◽  
T.W. David ◽  
A.T. Talabi
Keyword(s):  
Cancer Risk ◽  
Ionizing Radiation ◽  
Dose Rate ◽  
Health Effect ◽  
Radioactive Material ◽  
Annual Dose ◽  
Mining Sites ◽  
Dose Rates ◽  
Safe Limit ◽  
Ambient Dose

The work scenarios involved in the mining of tantalite a radioactive material expose the miners to ionizing radiation from the ore and the surrounding environment. The dose level in the mine air may be higher than the safe limit due to various contributory sources of ionizing radiation such as radionuclides from rocks, effluents, sand, and radon gas that emanates from caves and this can be of health detriment to the miners. Measurements of ambient dose rates in four selected mining sites have been investigated. Gamma absorbed dose rates were measured in air onsite at Komu, Sepenteri, Gbedu, and Eluku mining sites in Oke-Ogun areas of Oyo State, Nigeria using GammaRAE II dosimeter. Radiation dose to risk software was used to estimate the cancer risk for the period the miners spent onsite. The measured mean dose rate at the sites falls within the range of (19-240) nSv/y and the estimated annual dose rate, cumulative dose, and cancer risk fall within the range of (37-314) μSv/y, (4.0 ̶ 11.1) mSv and (0.5 ̶ 4.5) E-04 respectively. The upper limits of the range for the radiological parameters are all above the safe limit. The health implication of that is that increased work activities at these mining sites may over the years have a negative health effect on the miners. The exposure time of workers can be reduced through proper planning of working shifts for the miners.

Dose Rate Profile Surrounding a Repository

2013 ◽  
Author(s):  
J. Parson ◽  
A. Brandl ◽  
N. Zoeger ◽  
R. Koppitsch
Keyword(s):  
Monte Carlo ◽  
Dose Rate ◽  
Simulation Data ◽  
Dose Rates ◽  
Monte Carlo Techniques ◽  
Analytical Functions ◽  
Detector Distance ◽  
Waste Repository ◽  
Rate Profile

The focus of this research was to analyze the dose rate profile around a waste repository using Monte Carlo techniques. Dose rates at various heights and distances were analyzed outside of the waste repository using MCNPX [1]. The heights measured extended the height of the building and the distances varied between 0 and 22 m away from the waste repository. The simulation data were fitted by smooth analytical functions for different height levels and distances, such that vertical and horizontal dose rates as functions of source-detector distance were achieved.

scholarly journals Radiation Awareness for Endovascular Abdominal Aortic Aneurysm Repair in the Hybrid Operating Room: An Instant Operator Risk Chart for Daily Practice

2021 ◽  
pp. 152660282110074
Author(s):  
Quirina M. B. de Ruiter ◽  
Frans L. Moll ◽  
Constantijn E. V. B. Hazenberg ◽  
Joost A. van Herwaarden
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Effect Size ◽  
Radiation Risk ◽  
Dose Limit ◽  
Access Site ◽  
Femoral Access ◽  
Dose Rates ◽  
Rate Prediction ◽  
Operator Dose

Introduction: While the operator radiation dose rates are correlated to patient radiation dose rates, discrepancies may exist in the effect size of each individual radiation dose predictors. An operator dose rate prediction model was developed, compared with the patient dose rate prediction model, and converted to an instant operator risk chart. Materials and Methods: The radiation dose rates (DRoperator for the operator and DRpatient for the patient) from 12,865 abdomen X-ray acquisitions were selected from 50 unique patients undergoing standard or complex endovascular aortic repair (EVAR) in the hybrid operating room with a fixed C-arm. The radiation dose rates were analyzed using a log-linear multivariable mixed model (with the patient as the random effect) and incorporated varying (patient and C-arm) radiation dose predictors combined with the vascular access site. The operator dose rate models were used to predict the expected radiation exposure duration until an operator may be at risk to reach the 20 mSv year dose limit. The dose rate prediction models were translated into an instant operator radiation risk chart. Results: In the multivariate patient and operator fluoroscopy dose rate models, lower DRoperator than DRpatient effect size was found for radiation protocol (2.06 for patient vs 1.4 for operator changing from low to medium protocol) and C-arm angulation. Comparable effect sizes for both DRoperator and DRpatient were found for body mass index (1.25 for patient and 1.27 for the operator) and irradiated field. A higher effect size for the DRoperator than DRpatient was found for C-arm rotation (1.24 for the patient vs 1.69 for the operator) and exchanging from femoral access site to brachial access (1.05 for patient vs 2.5 for the operator). Operators may reach their yearly 20 mSv year dose limit after 941 minutes from the femoral access vs 358 minutes of digital subtraction angiography radiation from the brachial access. Conclusion: The operator dose rates were correlated to patient dose rate; however, C-arm angulation and changing from femoral to brachial vascular access site may disproportionally increase the operator radiation risk compared with the patient radiation risk. An instant risk chart may improve operator dose awareness during EVAR.

Kinetics of DNA Repair Under Chronic Irradiation at Low and Medium Dose Rates in Repair Proficient and Repair Compromised Normal Fibroblasts

2021 ◽  
Author(s):  
Elena K. Zaharieva ◽  
Megumi Sasatani ◽  
Kenji Kamiya
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dose Rate ◽  
Dose Response ◽  
Chronic Irradiation ◽  
Dose Rates ◽  
Chronic Radiation ◽  
Damage Repair ◽  
Kinetics Of ◽  
Medium Dose

We present time and dose dependencies for the formation of 53BP1 and γH2AX DNA damage repair foci after chronic radiation exposure at dose rates of 140, 250 and 450 mGy/day from 3 to 96 h, in human and mouse repair proficient and ATM or DNA-PK deficient repair compromised cell models. We describe the time/dose-response curves using a mathematical equation which contains a linear component for the induction of DNA damage repair foci after irradiation, and an exponential component for their resolution. We show that under conditions of chronic irradiation at low and medium dose rates, the processes of DNA double-strand breaks (DSBs) induction and repair establish an equilibrium, which in repair proficient cells manifests as a plateau-shaped dose-response where the plateau is reached within the first 24 h postirradiation, and its height is proportionate to the radiation dose rate. In contrast, in repair compromised cells, where the rate of repair may be exceeded by the DSB induction rate, DNA damage accumulates with time of exposure and total absorbed dose. In addition, we discuss the biological meaning of the observed dependencies by presenting the frequency of micronuclei formation under the same irradiation conditions as a marker of radiation-induced genomic instability. We believe that the data and analysis presented here shed light on the kinetics of DNA repair under chronic radiation and are useful for future studies in the low-to-medium dose rate range.

scholarly journals Serum Metabolomic Alterations Associated with Cesium-137 Internal Emitter Delivered in Various Dose Rates

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270
Author(s):  
Heng-Hong Li ◽  
Yun-Tien Lin ◽  
Evagelia C. Laiakis ◽  
Maryam Goudarzi ◽  
Waylon Weber ◽  
...  
Keyword(s):  
Dose Rate ◽  
Cumulative Dose ◽  
Low Dose ◽  
Biological Effects ◽  
Serum Samples ◽  
Dose Rates ◽  
Sphingosine 1 Phosphate ◽  
Cesium 137 ◽  
Dose Rate Effect ◽  
Medium Dose

Our laboratory and others have use radiation metabolomics to assess responses in order to develop biomarkers reflecting exposure and level of injury. To expand the types of exposure and compare to previously published results, metabolomic analysis has been carried out using serum samples from mice exposed to 137Cs internal emitters. Animals were injected intraperitoneally with 137CsCl solutions of varying radioactivity, and the absorbed doses were calculated. To determine the dose rate effect, serum samples were collected at 2, 3, 5, 7, and 14 days after injection. Based on the time for each group receiving the cumulative dose of 4 Gy, the dose rate for each group was determined. The dose rates analyzed were 0.16 Gy/day (low), 0.69 Gy/day (medium), and 1.25 Gy/day (high). The results indicated that at a cumulative dose of 4 Gy, the low dose rate group had the least number of statistically significantly differential spectral features. Some identified metabolites showed common changes for different dose rates. For example, significantly altered levels of oleamide and sphingosine 1-phosphate were seen in all three groups. On the other hand, the intensity of three amino acids, Isoleucine, Phenylalanine and Arginine, significantly decreased only in the medium dose rate group. These findings have the potential to be used in assessing the exposure and the biological effects of internal emitters.

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