Comprehensive Organizational and Methodical Approaches to Decommissioning of Radwaste Repositories

2019 ◽  
pp. 32-39
Author(s):  
А. Майзик ◽  
A. Mayzik ◽  
И. Кореньков ◽  
I. Korenkov ◽  
А. Цовьянов ◽  
...  
Keyword(s):  
Specific Activity ◽  
Core Sample ◽  
Subsurface Water ◽  
Radiation Doses ◽  
Building Structures ◽  
Dose Equivalent ◽  
Background Values ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Ambient Dose

Purpose: Development of comprehensive organizational and methodical approaches to decommissioning of shallow radwaste (RW) repositories. Material and methods: The following researches were conducted during assessment of radiation and hygiene situation: - assessing the state of physical barriers of repositories (tanks) of solid and liquid RW; - assessing radiation situation at the repository site before and after remediation; - measuring specific activity of 90Sr and 137Cs in ground and subsurface water, core sample, soils, building structures. Methods: on foot gamma survey; gamma-ray spectrometric measurement of radionuclides in environmental samples using a stationary spectrometer; radiochemical extraction of radionuclides and their radiometry. Results: The surveys were performed in 2014–2016. They delivered data on gamma dose rate at the RW repository site, specific activity of 90Sr and 137Cs in ground and subsurface water, core sample, soils, building structures. The surveys showed that content of 90Sr in subsurface water varied from 0.25 to 0.4 Bq/kg, while content of 137Cs was below the detection threshold (0.01 Bq per sample). It was founded that distribution of 90Sr and 137Cs in soil (core sample) forming the top layer of the area is highly uneven. In some cases specific activity of soil exceeded 1000 Bq/kg (C-23 well at the depth of 2.75 m and C-24 well at the depth of 5 m). In all other cases specific activity of the core sample did not exceed 10 Bq/kg, and specific activity of soil was up to 50 Bq/kg which is over background values. The ambient dose equivalent rate at the site varied from 0.1 to 0.3 µSv/h. After remediation activities content of radionuclides in soil and subsurface water was at the levels of background values. More than 6700 measurements were performed (more than 2400 measurements of the ambient dose equivalent rate, more than 4100 measurements of beta-contamination of work surfaces and equipment, and more than 200 measurements of specific and volumetric activity of environmental samples). Conclusions: This work allowed to substantiate technical solutions, procedure of RW accounting and control, using of shelters and mobile systems for radiation safety of the personnel and environmental protection. It was demonstrated that average external radiation doses for the workers involved in decommissioning activities did not exceed 0.7 mSv (variation from 0.16 to 1.7 mSv), while internal radiation doses varied from 0.35 to 3.3 µSv. Density of beta-contamination of the site did not exceed 38 beta-particles/(cm2∙min) which corresponds to background values. The ambient dose equivalent rate of the site was within 0.09-0.15 µSv/h after the work has been done.

scholarly journals Calculating radiation dose rate from online real-time environmental -spectrum using NaI(Tl) detector

2021 ◽  
Vol 11 (1) ◽  
pp. 16-25
Author(s):  
Thu Bac Vuong ◽  
Hoang Tuan Truong ◽  
Duc Thang Duong ◽  
Dac Dung Bui ◽  
Duc Viet Cao ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Real Time ◽  
Specific Activity ◽  
Radioactive Isotopes ◽  
Dose Equivalent ◽  
Radiation Dose Rate ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Ambient Dose

Calculating gamma radiation dose rate from online real-time environmental gamma spectrum using NaI(Tl) detector has been developed into a software named RADAPROC V.1 in the Center for Operating the National Network of Environmental Radiation Monitoring And Warning (CONNERMAW). Currently, hundreds of online gamma spectra per day from online monitoring stations are processed to calculate the total ambient dose equivalent rate and the ambient dose equivalent rate of typical natural radioactive isotopes such as K-40, Bi-214, Tl-208 according to the method of using the function G(E) and the photo-peak area method. The calculated results have been compared with the results of calculating the dose rate from the specific activity of radioactive isotopes in soil samples collected at the same monitoring location and analyzed in the laboratory. The difference between the methods is less than 25%. The ambient dose equivalent rates of typical natural radioactive isotopes are a bit higher than those calculated with SARA-NMC software. The software will be improved shortly for better results.

scholarly journals Radiation survey around “the 30th shipyard” company: 30 years after the accident

2020 ◽  
Vol 99 (7) ◽  
pp. 674-681
Author(s):  
Alexey V. Titov ◽  
Natalia K. Shandala ◽  
Dmitry V. Isaev ◽  
Natalya Y. Novikova ◽  
Vladimir A. Seregin ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Specific Activity ◽  
Soluble Form ◽  
Dose Equivalent ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Solid Radioactive Waste ◽  
60Co Activity ◽  
Radioactive Trace ◽  
Ambient Dose

Introduction. The objective of this work was the radiation survey in the vicinity of “The 30th Shipyard” Company. The studies were carried out during the period between 2014 and 2016 within the supervision area and in the area of the radioactive trace formed after the accident of 1985 in the nuclear submarine.Material and methods. The following methods were used in the course of the survey: pedestrian gamma surveys, gamma spectrometry measurements of radionuclides using a gamma spectrometer, and radiochemical extraction of 90Sr, followed by measurement of its activity at radiometric installations.Results. Gamma ambient dose equivalent rate within the supervision area beyond the radioactive trace varies within the range between 0.09 and 0.18 µSv/h. The specific activities of 90Sr, 137Cs, and 235U in soil do not exceed 11, 34, and 5.8 Bq/kg, respectively. The specific activity of 60Co in the soil of the Dunay village is lower 0.42 Bq/kg and does not exceed 4.9 Bq/kg at the rest part of the supervision area. The area of the radioactive trace limited by 0.13 µSv/h iso-line does not exceed 0.5 km2, while that limited by 0.3 µSv/h iso-line - 0.0063 km2. Within the area of the trace, the highest value of the gamma dose rate accounts for 0.60 µSv/h. Soils contaminated with emergency radionuclides do not belong to solid radioactive waste. Emergency radionuclides migrated in soil up to 20 cm depth. Today, 137Cs is firmly fixed in the soil. 40-45% of 60Co activity is in acid-soluble form. Under specific conditions, it can migrate deep into the soil and be accessible to plants.Conclusions. Within the supervision area of “The 30th Shipyard” Company, except for the area of the radioactive contamination trace induced by the accident, the radiation situation is the same as that in the area of the Primorskiy Krai. The soil of the radioactive trace does not belong to solid radioactive waste. In the future, the improvement of the radiation situation on the trace will be mainly due to the physical decay of radionuclides.

Radiation Survey in the Area of Peaceful Nuclear Explosion «Takhta-Kugulta»

2021 ◽  
Vol 66 (2) ◽  
pp. 13-22
Author(s):  
A. Titov ◽  
N. Shandala ◽  
D. Isaev ◽  
Yu. Bel'skih ◽  
M. Semenova ◽  
...  
Keyword(s):  
Specific Activity ◽  
Nuclear Explosion ◽  
Soil Surface ◽  
Mean Value ◽  
Surface Contamination ◽  
Dose Equivalent ◽  
Tritium Content ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Ambient Dose

Purpose: Radiation survey in the area of peaceful nuclear explosion «Takhta-Kagylta» in the Stavropol Region. Material and methods: Radiation survey was performed on the territory of the protected area and on the territory of the 30-km zone from the explosion site. Methods of pedestrian gamma survey with a portable spectrometric complex Multirad-M were used in the course of the survey, along with gamma spectrometric and radiochemical measurements of radionuclide activities in samples and radiochemical separation of 90Sr and 137Cs. The measurement of tritium activity concentration in water was carried out using a low-background liquid alpha-beta radiometer Quantulus-1220. Results: The highest average value of gamma ambient dose equivalent rate was obtained in the area of the peaceful nuclear explosion site. A value of ambient dose equivalent rate at the area between the site and Kevsala village is lower than on the site, but higher than in Kevsala village and in other settlements. The mean value of the surface contamination of soil with 137Cs on the site was 0.43 kBq/m2, while that of 90Sr was 0.055 kBq/m2. Average values of soil surface contamination with radionuclides in the settlements located in the area of the explosion vary over the range between 0.16 and 0.37 kBq/m2 for 137Cs and between 0.035 and 0.066 kBq/m2 for 90Sr. 241Am specific activity values were below the minimum detectable activity (0.01 – 0.04 kBq/m2 at the time of the soil sample measurement of 10–30 h). The contents of 3H, 90Sr and 137Cs radionuclides in drinking water and water of the surface water reservoirs is significantly lower than the intervention levels established in NRB-99/2009. Conclusions: Radiation situation at the location of the technological well complies with the requirements of SanPiN 2.6.1.2819-10 “Radiation Safety and Protection of the Population Living in the Areas of Peaceful Nuclear Explosions (1965 – 1988)”, and does not pose a threat to the health of the population when staying there. It is necessary to arrange the territory of the protection area and technological (charging) well in accordance with the requirements of SanPiN 2.6.1.2819–10. Within the framework of long-term radiation monitoring, it is necessary to provide for the monitoring of the tritium content in the produced gas and in the groundwater of the Krasnogvardeiskoe deposit (located in the direction of the spread of groundwater from the location of the peaceful nuclear explosion).

scholarly journals Study of the screening survey using an ambient dose equivalent rate survey meter in criticality accidents

2019 ◽  
Vol 6 (0) ◽  
pp. 152-155
Author(s):  
Katsuya Hoshi ◽  
Norio Tsujimura ◽  
Tadayoshi Yoshida ◽  
Osamu Kurihara ◽  
Eunjoo Kim ◽  
...  
Keyword(s):  
Dose Equivalent ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Criticality Accidents ◽  
Screening Survey ◽  
Ambient Dose

Correction Coefficients for Measuring the Ambient Dose Equivalent Rate of Neutrons

ANRI ◽  
2021 ◽  
Vol 0 (4) ◽  
pp. 32-40
Author(s):  
Alexander Alexeev ◽  
Vladimir Pikalov ◽  
Pavel Alexeev
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Dose Equivalent ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Ambient Dose

Calculations of the response for the most widely used neutron dosimeters at the Russian nuclear power plant (NPP) have been performed. It is shown that in some cases it is necessary to introduce a correction for the measured value of the ambient dose equivalent rate (AEDR). The experimentally tested values of the correction for measuring AEDR in the containment rooms of NPP with VVER-1200 are given.

scholarly journals Indoor Radon Measurements Using Radon Track Detectors and Electret Ionization Chambers in the Bauxite-Bearing Areas of Southern Adamawa, Cameroon

2020 ◽  
Vol 17 (18) ◽  
pp. 6776
Author(s):  
Saïdou ◽  
Oumar Bobbo Modibo ◽  
Ndjana Nkoulou II Joseph Emmanuel ◽  
Olga German ◽  
Kountchou Noube Michaux ◽  
...  
Keyword(s):  
Indoor Radon ◽  
Geometric Mean ◽  
Reference Level ◽  
Dose Equivalent ◽  
Ionization Chambers ◽  
The Public ◽  
Average Value ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Ambient Dose

The current work deals with indoor radon (222Rn) concentrations and ambient dose-equivalent rate measurements in the bauxite-bearing areas of the Adamawa region in Cameroon before mining from 2022. In total, 90 Electret Ionization Chambers (EIC) (commercially, EPERM) and 175 Radon Track Detectors (commercially, RADTRAK2) were used to measure 222Rn concentrations in dwellings of four localities of the above region. A pocket survey meter (RadEye PRD-ER, Thermo Scientific, Waltham, MA, USA) was used for the ambient dose-equivalent rate measurements. These measurements were followed by calculations of annual doses from inhalation and external exposure. 222Rn concentrations were found to vary between 36 ± 8–687 ± 35 Bq m−3 with a geometric mean (GM) of 175 ± 16 Bq m−3 and 43 ± 12–270 ± 40 Bq m−3 with a geometric mean of 101 ± 21 Bq m−3 by using EPERM and RADTRAK, respectively. According to RADTRAK data, 51% of dwellings have radon concentrations above the reference level of 100 Bq m−3 recommended by the World Health Organization (WHO). The ambient dose equivalent rate ranged between 0.04–0.17 µSv h−1 with the average value of 0.08 µSv h−1. The inhalation dose and annual external effective dose to the public were assessed and found to vary between 0.8–5 mSv with an average value of 2 mSv and 0.3–1.8 mSv with an average value of 0.7 mSv, respectively. Most of the average values in terms of concentration and radiation dose were found to be above the corresponding world averages given by the United Nations Scientific Commission on the Effects of Atomic Radiation (UNSCEAR). Even though the current exposure of members of the public to natural radiation is not critical, the situation could change abruptly when mining starts.

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