scholarly journals GAMMA DOSE RATE ANALYSIS IN BIOLOGICAL SHIELDING OF HTGR-10 MWth PEBBLE-BED REACTOR

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
Hery Adrial ◽  
Amir Hamzah ◽  
Entin Hartini
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Minimum Thickness ◽  
Critical Height ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
The Core ◽  
Rate Analysis

GAMMA DOSE RATE ANALYSIS IN BIOLOGICAL SHIELDING OF HTGR-10 MWth PEBBLE BED REACTOR. HTGR-10 MWth is a high-temperature gas-cooled reactor. The fuel and moderator are pebble shaped with a radius of 3 cm. One fuel pebble consists of thousands of UO2 kernels with a density of 10.4 gram/cc and the enrichment rate of 17%. The core of HTGR-10 MWth is the center of origin of neutrons and gamma radiation resulting from the interaction of neutrons with pebble fuel, moderator and biological shield. The various types of radiations generated from such nuclear reactions should be monitored to ensure the safety of radiation workers. This research was conducted using MCNP-6 Program package with the aim to calculate and analyze gamma radiation dose in biological shield of HTGR-10 MWth. In this study, the biological shield is divided into 10 equal segments. The first step of the research is to benchmark the created program against the critical height of HTR-10. The results of the benchmarking show an error rate of ± 1.1327%, while the critical core height of HTGR 10 MWth for the ratio of pebble fuel and pebble moderator (F:M) of 52: 48 occurs at a height of 134 cm. The rate of gamma dose at the core is 3.0052E + 05 mSv/hr. On the biological shield made of regular concrete with a density of 2.3 grams/cc, the rate of gamma dose decreases according to an equation y = 0.0042 e-0.03x. Referring to Perka Bapeten no 4 of 2013, the safe limits for workers and radiation protection officers will be achieved if the minimum thickness of biological shield is 115 cm with gamma dose rate of 0 mSv/hour.Keywords: Gamma dose rate, HTGR 10 MWth, biological shield, pebble

Primary Shielding Design for an Optimized Molten Salt Reactor

2013 ◽  
Author(s):  
Zhihong Zhang ◽  
Xiaobin Xia ◽  
Jianhua Wang ◽  
Changyuan Li
Keyword(s):  
Molten Salt ◽  
Dose Rate ◽  
Gamma Dose ◽  
Acceptable Level ◽  
Gamma Dose Rate ◽  
Molten Salt Reactor ◽  
Thermal Shield ◽  
Oak Ridge ◽  
The Core ◽  
Shielding Design

Molten salt reactor (MSR) system, a candidate of the Generation IV reactors, has inherent safety, on-line refueling and good neutron economy as typical advantages. An optimized MSR is developed by changing the size of fuel channel and the graphite-to-molten salt volume radio, based on the Molten-Salt Reactor Experiment (MSRE), which was originally developed at the Oak Ridge National Laboratory (ORNL). In this paper, shielding calculations for the optimized MSR are presented. The goal of this study is to determine the necessary shielding to decrease the neutron and gamma dose rate to the acceptable level according to national regulations. The operating temperature of the optimized MSR is designed in the range of 500 °C–700 °C, heat removal is also considered in the shielding design. The shielding calculations are carried out by using Monte Carlo method. The shielding system of the optimized MSR consists of 7 zones: the core, the core can, the reactor vessel, the thermal shield, the reactor cell containment, the shield tank and the concrete wall. The combinations of shielding materials in the thermal shield were evaluated. The thermal shield filled with carbon steel balls and circulating water gets an excellent shielding performance and heat removing effects. The neutron spectra and dose distributions, as well as the energy deposition over different shields have been analyzed. The total neutron dose rate outside the thermal shield is attenuated by a factor of about 104, and the gamma dose rate by a factor of about 103. These results show that the shielding design could low dose rate to an acceptable level outside the shielding and far below dose limit required.

Atmospheric radioactivity measurements at the SMEAR Estonia Station

2020 ◽  
Author(s):  
Heikki Junninen ◽  
Jussi Paatero ◽  
Urmas Hõrrak ◽  
Xuemeng Chen
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Aerosol Particles ◽  
Chem Phys ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Air Ions ◽  
Atmospheric Radioactivity ◽  
Atmospheric Radon ◽  
Radioactivity Measurements

<p>The SMEAR Estonia is a Station for Measuring Ecosystem-Atmosphere Relations (SMEAR). It is built on the same concept as the Finnish SMEAR stations <sup>[1]</sup> and belongs to the same measurement network. It is located in a hemiboreal forest at Järvselja, South-Eastern Estonia (58.2714 N, 27.2703 E at 36 m a.s.l.) <sup>[2]</sup>. The Estonian University of Life Sciences runs long-term measurements on meteorological parameters, trace gases and fluxes at the station. Atmospheric aerosol and air ions measurements are deployed by the University of Tartu (UT). </p><p> </p><p>Our main interest at UT lies in characterising atmospheric ions and aerosols, studying their connections to atmospheric new particle formation and cloud processes, and understanding the impacts of these processes on air quality, local weather and climate. Air ions are known to participate in forming atmospheric new particles <sup>[3]</sup>. Newly formed aerosol particles have the potential to modify cloud properties, once they reach big enough sizes via condensational and coagulational growth<sup>[4]</sup>. Air ions are primarily produced by the ionisation of air molecules, with the ionisation energy provided by natural radioactivity present in the atmosphere. The initial ionisation produces are subject to different dynamic processes, including charge transfer, clustering, coagulation and condensational growth <sup>[5]</sup>. At UT, we are launching a five-year project, starting from Jan. 2020, to investigate how atmosphere transforms the new-born air ions to climatically relevant aerosol particles. In order to get insights into the transformation process, atmospheric radioactivity measurements are crucial together with air ion and aerosol measurements.</p><p> </p><p>In the lower troposphere, ionization of the atmospheric originates from the decay of radon and other radioactive nuclides in the air and the Earth's crust as well as cosmic radiation. In collaboration with the Finnish Meteorological Institute, we initiated atmospheric radioactivity measurements at the SMEAR Estonia. The total gamma radiation (50 keV to 1.3 MeV) is measured with a gamma radiation meter (RADOS RD-02L) (since June 2019). The atmospheric radon is monitored using a filter-based Geiger-Müller counter (since Nov. 2019), which is a one-counter variation of an earlier design<sup>[6]</sup>. Atmospheric radon concentration is determined based on deposited beta activity. Preliminary results show that SMEAR Estonia (mean gamma dose rate = 0.03 uSv/h, mean radon conc. = 2.5 Bq/m<sup>3</sup>) has less ionization than SMEAR II station in Finland (mean gamma dose rate = 0.08 uSv/h, mean radon conc. = 2 Bq/m<sup>3</sup>). The linkage of this observation to air ion properties is under progress.</p><p>References:</p><p>[1]       Hari P., Kulmala M., Boreal Environ. Res. <strong>2005</strong>, 10, 315-322.</p><p>[2]       Noe S. M. et al., Forestry Studies <strong>2015</strong>, 63.</p><p>[3]       Tammet H. et al., Atmospheric Research <strong>2014</strong>, 135-136, 263-273.</p><p>[4]       Merikanto J. et al., Atmos. Chem. Phys. <strong>2009</strong>, 9, 8601-8616.</p><p>[5]       Chen X. et al. Atmos. Chem. Phys. <strong>2016</strong>, 16, 14297-14315.</p><p>[6]       Paatero J. et al., Radiat. Prot. Dosim. <strong>1994</strong>, 54, 33-39.</p>

ASSESSMENT OF INDOOR GAMMA RADIATION AND DETERMINATION OF EXCESS LIFETIME CANCER RISK IN TEHRAN IN WINTER AND SPRING 2017

2018 ◽  
Vol 184 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Marjan Hashemi ◽  
Leila Akhoondi ◽  
Mohammad Hossien Saghi ◽  
Akbar Eslami
Keyword(s):  
Cancer Risk ◽  
Gamma Radiation ◽  
Dose Rate ◽  
Annual Effective Dose ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Lifetime Cancer Risk ◽  
Average Value ◽  
Excess Lifetime Cancer Risk

Abstract Natural radiation is a feature of the environment in which we live. One of the contributions of human exposure to ionizing radiation due to natural sources arises from gamma radiation. Therefore, present study was aimed to evaluate and map indoor gamma dose rate in Tehran. The corresponding annual effective dose (AED) and excess lifetime cancer risk (ELCR) were also calculated. All measurements were performed by a Geiger Muller detector in 43 dwellings in Tehran. The average indoor gamma dose rate in Tehran was appointed as 343.2 nGy/h. AED and ELCR were calculated as 2.4 mSv and 10.3 × 10−3, respectively. The evaluated indoor gamma dose rate and calculated AEDs and lifetime cancer risk were found higher than the world average value.

scholarly journals Inter-calibration of gamma dose rate detectors on the European scale

2009 ◽  
Vol 44 (5) ◽  
pp. 777-784 ◽  
Author(s):  
U. Stöhlker ◽  
M. Bleher ◽  
T. Szegvary ◽  
F. Conen
Keyword(s):  
Dose Rate ◽  
Gamma Dose ◽  
Gamma Dose Rate

Harmonized radon data in the European Atlas of Natural Radiation

2021 ◽  
Author(s):  
Giorgia Cinelli ◽  
Peter Bossew ◽  
Marc De Cort ◽  
Valeria Gruber ◽  
Tore Tollefsen
Keyword(s):  
Ionizing Radiation ◽  
Dose Rate ◽  
Radon Concentration ◽  
Indoor Radon ◽  
Gamma Dose ◽  
European Countries ◽  
Gamma Dose Rate ◽  
Research Centre ◽  
Natural Radiation ◽  
Natural Sources

<p>As the scientific and knowledge service of the European Commission, the mission of the Joint Research Centre (JRC) is to support EU policies with independent evidence throughout the whole policy cycle. In particular, the JRC provides this support to the Directorate General for Energy by collecting, evaluating and reporting artificial environmental radioactivity measurements both for routine (REM database) and emergency preparedness (European Radiological Data Exchange Platform) purposes.<br>However, with the exception of potential large scale nuclear accidents, natural ionizing radiation is the largest contributor to the collective effective dose received by the world population. To gain a clearer overview of the natural sources of radioactivity, the JRC launched the European Atlas of Natural Radiation with the aim to provide insight into geographical variability of exposure components and their relative importance for total exposure to ionizing radiation.</p><p>The Atlas presents contributions from 100 experts in various fields, from 60 institutions such as universities, research centres, national and European authorities, and international organizations. In the first place, this Atlas aims to provide reference values and generate harmonised data for the scientific community and national competent authorities. It also offers an opportunity to the public to become familiar with the radioactive part of its natural environment. Intended as an encyclopaedia on natural radioactivity, the Atlas explains its different sources, i.e. cosmic and terrestrial radiation, and describes the current state-of-the art of knowledge by means of text, graphics and maps.</p><p>Being responsible for half of the natural dose, particular attention has been given to indoor radon, of which over one million measurements of long-term indoor radon concentration in ground-floor rooms of dwellings from 36 European countries were collected and aggregated as means within 10 km × 10 km grid cells. The updated version of the European Indoor Radon Map (December 2020) will be presented as well as the statistical analysis of the input data.</p><p>Geogenic Radon Potential and Geogenic Radon Hazard Index quantify the contribution of geogenic to indoor radon and are constructed using geogenic quantities, such as uranium concentrations in the ground, geology, soil permeability, soil radon concentration and terrestrial gamma dose rate.<br>Therefore, it was decided to focus the Atlas on the development of maps that display natural sources of radiation and also serve as quantities which predict geogenic radon. Maps of uranium, thorium and potassium concentrations in soil, covering most European countries, were created, while maps of uranium, thorium and potassium concentrations in bedrock are only available for some countries. A methodology for estimating the terrestrial gamma dose rate (based on ambient dose equivalent rate measurements) has been established, while the European terrestrial gamma dose rate map has been created using uranium, thorium and potassium concentration in soil. The practical use of the maps of the Atlas as geogenic quantities will be illustrated through different examples of scientific studies.</p><p>The Atlas is available in digital format and can be ordered as a printed version at https://remon.jrc.ec.europa.eu/ .</p><p> </p>

ASSESSMENT OF RADON AND THORON EXHALATION FROM SOILS AND DISSOLVED RADON IN GROUND WATER IN THE VICINITY OF ELEVATED GRANITIC HILL, CHIKKABALLAPUR DISTRICT, KARNATAKA, INDIA

2020 ◽  
Vol 190 (2) ◽  
pp. 185-192
Author(s):  
C G Poojitha ◽  
B K Sahoo ◽  
K E Ganesh ◽  
T S Pranesha ◽  
B K Sapra
Keyword(s):  
Ground Water ◽  
Dose Rate ◽  
Detailed Analysis ◽  
Physicochemical Parameters ◽  
Soil Samples ◽  
Gamma Dose ◽  
Gamma Dose Rate ◽  
Exhalation Rate ◽  
Groundwater Samples ◽  
Activity Measurements

Abstract In this paper, we intend to evaluate the rate of radon and thoron exhalation from soil with reference to the underlying bedrock and gamma dose rate in the environment of elevated granitic hill—Nandi hills of Karnataka. The measurement of exhalation rates for all the soil samples collected from study area was carried out using a continuous radon–thoron monitor (Smart RnDuo monitor). The surface exhalation rate of thoron from soil samples were found to vary from 4160 ± 326 to 21 822 ± 634 mBq m−2 s−1. The mass exhalation rate of radon from soil samples were found to vary from 76 ± 6 to 269 ± 19 mBq kg−1 h−1. Concentrations of radon activity measurements were carried out for all the groundwater samples from study area. A detailed analysis along with physicochemical parameters of water has been made and discussed in this research paper.

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