scholarly journals Characterization of NIS neutron irradiation facility for calibration and metrological application

2021 ◽  
Vol 12 ◽  
pp. 9
Author(s):  
Ahmed R. El-Sersy ◽  
Eman A. Sayed ◽  
Salwa H. Nagib ◽  
Reham Hamdy Bakr ◽  
Randa M.M. Mahmoud
Keyword(s):  
Dose Rate ◽  
Neutron Irradiation ◽  
Neutron Monitor ◽  
Standard Dose ◽  
Dose Ratio ◽  
Dose Rates ◽  
Calculated Dose ◽  
Combined Uncertainty ◽  
Standard Neutron ◽  
Scattering Contribution

In this study, the Neutron Irradiation Facility (NIF) of the National Institute of Standards (NIS) was characterized for metrological applications to improve the accuracy of the calibration process. The NIS neutron irradiation facility consists of a 5 Ci Am-Be and 0.1 μg Cf-252 sources. The flux and dose rate of the Am-Be source was calculated by using MCNP5 code simulation at different distances from the source. The dose rate delivered by the source was determined using NM2-neutron monitor at different source-to-detector distances. A comparison between the measured and the calculated dose rate was performed and the deviation between them was explained in the skeletal arrangement of room scattering contribution. A shadow cone was designed and constructed to determine the scattering contribution at different source-to-detector distances. The optimum source-distance used for calibration was specified. It was found that the Am-Be calculated flux vary with distances from about 107–104 (n/cm2.S−1). The measured and the calculated dose rates were in agreement up to 150 cm distance from the source center after which the measured dose was greater than that calculated. The determined neutron scattering calculated from the measured-to-calculate dose ratio increased from 7% to 25% with increased distances from 150 to 300 cm. Moreover, the standard dose used in the calibration should be measured by a standard neutron monitor at each distance due to the higher value of the room scattering contribution where the optimum distance for calibration was 150 cm. The combined uncertainty of the measured neutron dose was 4.04%.

scholarly journals Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828) on the coast of Ceara, Brazil

2010 ◽  
Vol 58 (spe4) ◽  
pp. 25-32 ◽  
Author(s):  
Wagner de S. Pereira ◽  
Alphonse Kelecom ◽  
Delcy de A. Py Júnior
Keyword(s):  
Dose Rate ◽  
Standard Dose ◽  
Natural Radionuclides ◽  
Absorbed Dose ◽  
Threshold Value ◽  
Average Dose ◽  
Absorbed Dose Rate ◽  
Dose Rates ◽  
A Value ◽  
Lead 210

A methodology was developed for converting the activity concentration of radionuclides (Bq kg-1) into absorbed dose rate (Gy y-1), aiming an approach to environmental radioprotection based on the concept of standard dose limit. The model considers only the internal absorbed dose rate. This methodology was applied to the cubera snapper fish (Lutjanus cyanopterus, Cuvier, 1828) caught off the coast of Ceará. The natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. The absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. The average dose rate due to these radionuclides was 5.36 µGy y-1, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 10³ mGy y-1), and similar to that found in the literature for benthic fish. Ra-226 and U-238 contributed 67% and 22% of the absorbed dose rate, followed by Th-232 with 10%. Ra-228 and Pb-210, in turn, accounted for less than 1% of the absorbed dose rate. This distribution is somewhat different from that reported in the literature, where the Ra-226 accounts for 86% of the absorbed dose rate.

scholarly journals Gross Gamma Dose Rate Measurements for TRIGA Spent Nuclear Fuel Burnup Validation

2002 ◽  
Author(s):  
P. L. Winston ◽  
J. W. Sterbentz
Keyword(s):  
Dose Rate ◽  
Spent Nuclear Fuel ◽  
Gamma Ray ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Primary Concern ◽  
Examination System ◽  
Dose Rates ◽  
Calculated Dose ◽  
Fuel Elements

Gross gamma-ray dose rates from six spent TRIGA fuel elements were measured and compared to calculated values as a means to validate the reported element burnups. A newly installed and functional gamma-ray detection subsystem of the In-Cell Examination System was used to perform the measurements and is described in some detail. The analytical methodology used to calculate the corresponding dose rates is presented along with the calculated values. Comparison of the measured and calculated dose rates for the TRIGA fuel elements indicates good agreement (less than a factor of 2 difference). The intent of the subsystem is to measure the gross gamma dose rate and correlate the measurement to a calculated dose rate based on the element s known burnup and other pertinent spent fuel information. Although validation of the TRIGA elements’ burnup is of primary concern in this paper, the measurement and calculational techniques can be used to either validate an element’s reported burnup or provide a burnup estimate for an element with an unknown burnup.

scholarly journals Enhancement of viability of radiosensitive (PBMC) and resistant (MDA-MB-231) clones in low-dose-rate cobalt-60 radiation therapy

2015 ◽  
Vol 48 (3) ◽  
pp. 158-165 ◽  
Author(s):  
Patrícia Lima Falcão ◽  
Bárbara Miranda Motta ◽  
Fernanda Castro de Lima ◽  
Celso Vieira Lima ◽  
Tarcísio Passos Ribeiro Campos
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Mononuclear Cells ◽  
Standard Dose ◽  
Breast Adenocarcinoma ◽  
Peripheral Blood Mononuclear ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Viability Assay

Abstract Objective: In the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231) cells line and radiosensitive peripheral blood mononuclear cells (PBMC), as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and Methods: The cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min–1 and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: Radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB- 231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48–72 hours post-radiation. Conclusion: Low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer.

scholarly journals Comparison of FLASH Proton Entrance and the Spread-Out Bragg Peak Dose Regions in the Sparing of Mouse Intestinal Crypts and in a Pancreatic Tumor Model

Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 4244
Author(s):  
Michele M. Kim ◽  
Ioannis I. Verginadis ◽  
Denisa Goia ◽  
Allison Haertter ◽  
Khayrullo Shoniyozov ◽  
...  
Keyword(s):  
Dose Rate ◽  
Bragg Peak ◽  
Standard Dose ◽  
Biological Effects ◽  
Entrance Region ◽  
Treatment Modalities ◽  
High Dose ◽  
Proton Radiotherapy ◽  
Dose Rates ◽  
Spread Out Bragg Peak

Ultra-high dose rate FLASH proton radiotherapy (F-PRT) has been shown to reduce normal tissue toxicity compared to standard dose rate proton radiotherapy (S-PRT) in experiments using the entrance portion of the proton depth dose profile, while proton therapy uses a spread-out Bragg peak (SOBP) with unknown effects on FLASH toxicity sparing. To investigate, the biological effects of F-PRT using an SOBP and the entrance region were compared to S-PRT in mouse intestine. In this study, 8–10-week-old C57BL/6J mice underwent 15 Gy (absorbed dose) whole abdomen irradiation in four groups: (1) SOBP F-PRT, (2) SOBP S-PRT, (3) entrance F-PRT, and (4) entrance S-PRT. Mice were injected with EdU 3.5 days after irradiation, and jejunum segments were harvested and preserved. EdU-positive proliferating cells and regenerated intestinal crypts were quantified. The SOBP had a modulation (width) of 2.5 cm from the proximal to distal 90%. Dose rates with a SOBP for F-PRT or S-PRT were 108.2 ± 8.3 Gy/s or 0.82 ± 0.14 Gy/s, respectively. In the entrance region, dose rates were 107.1 ± 15.2 Gy/s and 0.83 ± 0.19 Gy/s, respectively. Both entrance and SOBP F-PRT preserved a significantly higher number of EdU + /crypt cells and percentage of regenerated crypts compared to S-PRT. Moreover, tumor growth studies showed no difference between SOBP and entrance for either of the treatment modalities.

scholarly journals A COMPARATIVE STUDY OF TERRESTRIAL GAMMA DOSE RATE IN AIR MEASURED BY DIFFERENT PORTABLE SURVEY METERS AROUND THE PETROLEUM-PRODUCING AREAS OF THE-QAR PROVINCE, IRAQ

2021 ◽  
Vol 9 (01) ◽  
pp. 1171-1176
Author(s):  
Karwan F. Majeed ◽  
◽  
Yousif M. Zayir Al-Bakhat ◽  
Keyword(s):  
Dose Rate ◽  
Spectroscopic Analysis ◽  
Oil And Gas ◽  
Gas Production ◽  
Soil Samples ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Oil And Gas Production ◽  
Dose Rates ◽  
Calculated Dose

Two different survey-meters are used to measure the gamma dose rate inthe area of oil and gas production of the Thi-Qar province, southeast of Iraq. The obtained results are compared with those previously obtained by the gamma spectroscopic analysis of collected soil samples from the same study regions.The obtained dose rate by using RadEye (PRD) survey-meter was ranged (0.06-0.19)nGyh-1, while those by using Ludlum survey meter were ranged(10.23-33.48) nGyh-1. Gamma spectroscopic analysis of the collected samples showed that the calculated dose rate is ranged(14.77-38.78) nGyh-1which is higher than those obtained by RadEye (PRD) survey-meter and comparable with those obtained byLudlum survey meter. Using the gamma survey meters to determine the dose rates inside these regions cannot be trustedand the long methodology of the gamma spectroscopic analysis of the collected samples is highly required.

scholarly journals Radiological impact assessment in the terrestrial environment of Greece using innovative tools – Adaptation of ERICA Tool to actual measurements

2019 ◽  
Vol 24 ◽  
pp. 222
Author(s):  
M. Sotiropoulou ◽  
H. Florou ◽  
G. Kitis
Keyword(s):  
Dose Rate ◽  
Assessment Tool ◽  
Natural Radionuclides ◽  
Internal Exposure ◽  
Terrestrial Environment ◽  
Dose Rates ◽  
Measured Activity ◽  
Calculated Dose ◽  
Poaceae Family ◽  
Radiological Dose

In the present study, the radioactivity levels in terrestrial non-human biota and the transfer pathways in the ecosystem are examined. Grass of Poaceae family and herbivore mammals (ruminants) of Bovidae family and soil samples were collected during the period of 2010 to 2014, from grasslands of the Greek rural territory where sheep and goats were free-range grazing. Natural background radionuclides (226Ra, 228Ra, 228Th) and artificial radionuclides (137Cs, 134Cs, 131I) were detected in the collected samples using gamma spectrometry. The actual measured activity concentrations and site- specific data of the studied organisms were imported in ERICA Assessment Tool (Version 1.2.1, February 2016) in order to provide an insight of the radiological dose rates. Natural radionuclides exhibited significantly higher contribution to the total dose rate than the artificial ones. The radiological exposure to Fukushima-derived radionuclides was quite low and owed to internal exposure, mainly derived through the ingestion pathway. According to the screening levels, the calculated dose rate to the studied non-human biota was below the threshold levels. However, the obtained results may be proved useful in further research regarding the possible impact of protracted low level ionising radiation to non-human biota on the various levels of life’s organization.

Phase-field simulation of dose rate effect on the Cu precipitation with neutron irradiation

2021 ◽  
Vol 23 (7) ◽  
pp. 4217-4229
Author(s):  
Shahid Maqbool ◽  
Yongsheng Li ◽  
Suleman Muhammad ◽  
Zhengwei Yan ◽  
Shujing Shi
Keyword(s):  
Dose Rate ◽  
Neutron Irradiation ◽  
Phase Field ◽  
Volume Fraction ◽  
Rate Effect ◽  
Phase Field Simulation ◽  
Field Simulation ◽  
Cu Alloys ◽  
Dose Rate Effect

Radiation-enhanced precipitation (REP) in Fe–Cu alloys results in higher volume fraction and radius of Cu precipitates.

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.

Performance Assessment of a High-Level-Waste Repository in Clay

1988 ◽  
Vol 127 ◽  
Author(s):  
Jan L. Marivoet ◽  
Geert Volckaert ◽  
Arnold A. Bonne
Keyword(s):  
Performance Assessment ◽  
Maximum Dose ◽  
High Level Waste ◽  
Clay Layer ◽  
Geological Disposal ◽  
Dose Rates ◽  
Consequence Analysis ◽  
Calculated Dose ◽  
Order Of Magnitude ◽  
High Level

ABSTRACTPerformance assessment studies have been undertaken on the geological disposal of high-level waste in a clay layer in the framework of the CEC project PAGIS. The methodology applied consists of two consecutive steps : a scenario and a consequence analysis. The scenario analysis has indicated that scenarios of normal evolution, of human intrusion, of climatic change, of secondary glaciation effects and of faulting should be evaluated. For the consequence analysis as well deterministic “best estimate” as stochastic calculations, including uncertainty, risk and sensitivity analyses, have been elaborated.The calculations performed show that most radionuclides decay to negligible levels within the first fewjneters of the clay barrier. Just a few radionuclides, 99Tc, 135Cs and 237Np with its daughter nuclides 233U and 229Th can eventually reach the biosphere. The maximum dose rates arising from the geological disposal of HLW, as evaluated by the “best-estimate” approach are about 10−11 Sv/y for river pathways. If the sinking of a water well into the 150 m deep aquifer layer in the vicinity of the repository is considered together with a climatic change, the maximum calculated dose rate rises to a value of 3×10−7 Sv/y. The maximum dose rates evaluated by stochastic calculations are about one order of magnitude higher due to the considerable uncertainties in the model parameters. In the case of the Boom clay the estimated consequences of a fault scenario are of the same order of magnitude as the results obtained for the normal evolution scenario. The maximum risk is estimated from the results obtained through stochastic calculations to be about 5×10−8 per year. The sensitivity analysis has shown that the effective thickness of the clay layer, the retention factors of Tc, Cs and Np, and the Darcy velocity in the aquifer are parameters which strongly influence the calculated dose rates.

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