Development and characterization of a mobile γ spectrometer and its field deployment for in situ radioactivity measurements

A mobile γ–ray spectrometer (AMESOS) has been developed using a 3”×3” NaI(Tl) detector, a custom–made mounting holder, and portable electronics to perform in situ measurements of radioactivity. The spectrometer was calibrated using standard point sources and its absolute efficiency was determined. As a field test operation, AMESOS was deployed on the premises of the University of Athens Zografou campus focusing on estimating the NORM levels. Data were analyzed and used to create radiological maps for the metropolitan UoA campus for the first time. Besides natural radioactivity levels, trace concentrations of 137Cs were also detected, attributed to the Chernobyl fallout in Greece. An overall steady performance of the spectrometer was observed throughout the field operation. AMESOS is ready to be deployed for in situ studies of environmental radioactivity and radwaste management.

Studying Submarine Groundwater Discharge at the Cape Ayia: a Multi-Tracer Approach

Purpose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to provide a comprehensive study of the submarine groundwater discharge at Cape Ayia using the hydrological, hydrochemical and radiochemical methods, and to determine the flux of submarine groundwater including the nutrients. Methods and Results. The research werecarried out during the coastal expeditions nearby Cape Ayia on March 24, 2019, and on April 22–24, 2019 during the 106th RV “Professor Vodyanitsky” cruise (April 18 – May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2 %), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7 %) with the energy 911.6 keV. The basic elements of the main nutrient cycle were determined photocolorimetrically: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photocolorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known submarine groundwater discharges was studied. The distribution of the 226Ra, 228Ra isotopes was studied for the first time. The data on salinity, specific activity of 226Ra, 228Ra and the nutrients concentration permitted to determine the flows of submarine groundwaters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.

Studying Submarine Groundwater Discharge at the Cape Ayia: a Multi-Tracer Approach

Pupose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to represent a comprehensive study of the submarine groundwater discharge focus at the Cape Ayia using the hydrological, hydrochemical and radiochemical methods, as well as to determine the flux of submarine groundwater including the nutrients. Methods and Results. The scientific investigations were carried out during the coastal expeditions nearby the Cape Ayia on March 24, 2019, and also on April 22–24, 2019 during the 106th cruise of the R/V “Professor Vodyanitsky” (April 18–May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) in 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2%), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7%) with the energy 911.6 keV. The basic elements of the main biogenic cycle were determined using the photo-colorimetric means: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photo-colorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known focuses of the groundwater submarine discharge was studied. For the first time, the distribution of the 226Ra, 228Ra isotopes was studied. The data on salinity, volumetric activity of the 226Ra, 228Ra isotopes and the nutrients concentration permitted to determine the flows of submarine underground waters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.

Activity Concentrations Of Environmental Samples Collected In Samarkand Region Of Uzbekistan

The results of the investigations of the activity concentration of natural radionuclides in certain building materials and foodstuff samples obtained from the Nurabad district of the Samarkand region of Uzbekistan are presented. The gamma radiation spectra of the samples were measured in Marinelli beaker geometry on γ- spectrometer with a Ge(Li) detector and energy resolution 6% on the 1332 keV line of 60Co. A personal computer and standard computer programs were used to accumulate and process the spectra. The characteristic density of the samples ranged from 140 to 1810 g/l. The activity concentration of 40K was observed to be comparatively higher than that of both 226Ra and 232Th in all the studied samples. The results reveal that the low activity of 137Cs in the samples is attributed due to its half-life decay period.

Design of the Sampling Measurement and Radiochemistry Lab in the Nuclear Island of HTR-PM

Radiation monitoring system is very important to the safe operation of the nuclear power plant. The radiation monitor, including the on-line type and the off-line type, can provide the radioactive level for a given system, certain areas, or unique substance promptly. However, as a supplementary method, the sampling measurement can supply more accurate information about the source term. In this paper, we present the design of the sampling measurement in the nuclear island of HTR-PM. The sampling measurement contains the helium sampling from the primary coolant, the radioactive dust sampling from the primary loop, the liquid sampling from the tritiated water and some process systems, the gas sampling from certain areas, etc. The frequency of the sampling measurement depends on regulatory requirements and actual operational demands. The control values of the samples are settled on the basis of the source term analysis and regulatory requirements. The radiochemistry lab has been designed to meet the requirement of the sampling measurement, in which the main instruments include a NaI γ spectrometer, two high-purity germanium γ spectrometers, a four-channel ultralow background α/β analyzer, and a low background liquid scintillation counter. The characteristics of these instruments will be described in details in the paper.