Radiation Monitoring System Research Articles

РАДІАЦІЙНИЙ СТАН ЗОНИ ВІДЧУЖЕННЯ В 2023 РОЦІ ЗА РЕЗУЛЬТАТАМИ РАДІАЦІЙНО-ЕКОЛОГІЧНОГО МОНІТОРИНГУ

The article presents results of radiation and environmental monitoring in the Exclusion Zone for the year 2023, after de-occupation of the territory, which was carried out in accordance with the current regulation of work, with the exception of objects on which it is temporarily impossible to carry out work due to the lack of safe access. In 2022, due to the full-scale invasion of russian federation, radiation monitoring of the environment was interrupted, monitoring of radiation-hazardous objects and environmental components of the Exclusion Zone was not carried out. Implementation of priority measures to restore the radiation and environmental monitoring system in the Exclusion Zone, after occupation by russian troops, made it possible to resume the work of the automated radiation monitoring system points, to create an additional network of measurement of gamma radiation indicators in the Exclusion Zone, to restore work of the central analytical laboratory and to restore the work of aspiration units. Thus, the enterprise resumed obtaining the necessary data on the dose rate of gamma radiation, information on the radiation state of the surface layer of the atmosphere, radiation state of surface and underground waters, radiation state of landscapes and places of residence of self-settlers. According to the results of radiation and environmental monitoring in the Exclusion Zone in 2023, important analytical data were obtained: - Maximum power values of the ambient dose equivalent of gamma radiation are characteristic of the territories in the northern and western 'traces' of radioactive fallout; - Radiation state of the Exclusion Zone air environment and its dynamics during 2023 were determined by the nature of surface contamination of the territory, man-made and biological factors, as well as meteorological conditions. Control levels exceeding by 2.5 times of 137Cs volumetric activity in the air was recorded in Chornobyl; - Surface waters remain an important route of radionuclide removal beyond the Exclusion Zone. Removal of 90Sr from Pripyat River in the area of Chornobyl in 2023 was at a level that was 2.4 times higher than the average value for the last 5 years; - As a result of observations of the radiation state of underground waters, it was determined that the average value of radionuclide contamination of eocene and cenomanian-lower cretaceous water-bearing complexes does not exceed 1 Bq/m3 for 137Cs and 5.7 Bq/m3 for 90Sr; - Monitoring results at landscape landfills indicate that the most contaminated component of the environment is the top layer of soil cover; - Radiation survey results of unauthorized residence places of the population in the Exclusion Zone showed that over the years there is an increase in the intake of 90Sr in the food products of 'self-settlers'.

An investigation of γ radiation detection with a CMOS imaging sensor.

In this study, a feasibility of γ radiation detection using complementary metal-oxide semiconductor (CMOS) image sensors with a neural network algorithm to extract the γ rays interacted pixels has been investigated. The responses characteristics of the CMOS imaging sensor to γ-ray is studied by placed in a γ fields produced by standard60Co or137Cs isotope sources. The supported preview frame rate of the CMOS image sensor is 25 fps, establishing the functional relationship between the gray level histograms and the dose rate through the neural network, the high energy γ-ray from60Co and137Cs source radiation dose rate in µSv/h level can be detected using the CMOS imaging sensor. The results show that the proposed method can effectively identify the number of photon particles which detected by the radiation monitoring system based on CMOS image sensor, and infer that the CMOS imaging sensor with a radiation signal extraction algorithm can be used as a dose warner for radiation protection purpose.

Early Warning Design for Environmental Radioactivity Using Unmanned Aircraft in a Radiation Monitoring System as an Effort to Maintain Public Health

Early Warning Design for Environmental Radioactivity Using Unmanned Aircraft in a Radiation Monitoring System as an Effort to Maintain Public Health

Bayesian non-parametric modeling by mixture of Kibble-Pólya tree to detect Low-Activity uranium contamination

Accurate detection of low-level radioactivity is critical for decommissioning projects in nuclear facilities, particularly in the design of radiation monitoring systems with a low false alarm rate. Utilizing a non-parametric Bayesian continuous probability distribution enables reliable mapping of potential contamination. Our method introduces a statistical test based on a Pólya tree prior, applied to radiation detection. The detection efficiency of this proposed Bayesian test is quantified using receiver-operating characteristic (ROC) curves and compared to a Bayesian test based on the Kibble bivariate gamma distribution developed for the same purpose. The results demonstrate that the new Bayesian test generally outperforms the previous method in terms of detection performance under very low signal-to-noise ratios, with improvements ranging from 3% to 28% against both stationary and non-stationary radiological backgrounds, respectively. This superiority is further reaffirmed through comparisons with alternative Bayesian and frequentist hypothesis tests, with gains estimated at 52% and 4%, respectively.

Information technologies in the construction of the field of radiation pollution of the locality and forecasting

The article examines the improvement of information technologies in the construction of the field of radiation contamination of the area based on the measured values of the impact factors of a nuclear explosion. Forecasting uses summaries of radioactive contamination centers and meteorological information. This process is quite well formalized and its practical implementation does not present great difficulties in automated systems for monitoring the radiation environment.Studies have shown that with a large heterogeneity of the source data by location (the presence of significant zones in which measurements were not carried out), this approach can unjustifiably overestimate or underestimate the calculated values in these zones. The local interpolation method was used to correct this effect. It is based on the assumption of the presence of local linear dependencies in the source data.In automated radiation monitoring systems, interpolation methods are used in the presence of a widespread network of stationary sensors connected to communication channels.The interpretation of radiation reconnaissance data using interpolation methods does not allow using a priori information about the parameters of the cell and the conditions for the formation of radiation contamination of the area. Joint accounting in the processing of these data allows you to combine the stages of forecasting and detection of the actual situation into a single process.

Ensuring radiation safety during dismantling, transportation and long-term storage of the SM-3 research reactor core

Described shortly here is a procedure of demounting, removal, transport and long-term storage of the SM-3 core, based on the previous experience of reactor refurbishment undertaken in 1991. Prior to performing refurbishment, computations and calculated data analysis were performed to prove radiation safety of this work, which included estimation of the activity level for activation products in the structural materials of the nuclear research reactor core and the radiation conditions at different stages of its handling. As evidenced by the calculated data, the activity of the main dose-forming radionuclide 60Co attains equilibrium in about 12 years of radiation exposure. Taking into account the fact that the time period between two refurbishments was longer than 12 years, the calculated values of the equivalent dose rate were normalized to the radiation monitoring data obtained during the previous refurbishment, taking into account the calculated activity of 60Co radionuclide. The normalization made it possible to confirm reliability of estimates. The obtained activity data of activation products and taking into account the time spent during the SM-3 refurbishment in 1991, the radiation impact on personnel was estimated. Calculated values of the anticipated effective radiation exposure doses to the personnel engaged in the refurbishment revealed that the main limits of the personnel radiation exposure established in accordance with NRB-99/2009 were not exceeded. Comparison of the results of calculating the equivalent dose rate with the results of radiation monitoring at various points allowed us to establish that during the calculation and analytical justification of the radiation safety of work, the assessment of reflected radiation was significantly underestimated. But the radiation monitoring data, personal radiation monitoring, as well as recorded data of automatic radiation monitoring system show that all work was performed in compliance with the requirements of regulatory documents in the field of radiation safety.

A statistical method for the assessment of metrological characteristics of reference materials

Standard reference materials of the composition and properties of substances and materials are used in both industrial and non-industrial sectors of society to ensure measurement uniformity and traceability in those types of measurements that cannot be provided using standards.
 During times of war and increased nuclear threat due to a full-scale invasion by an aggressor state, there is a need for heightened attention to the verification of ionizing radiation detection blocks, measurement channels of radiation monitoring systems, radiometers, and radiometric installations, as well as alpha, beta, and gamma radiation spectrometers.
 The aim of the paper is to demonstrate the method to evaluate the measurement uncertainty of reference materials (Europium-152 (Eu-152), Сaesium-137 (Cs-137), and Thorium-232 (Th-232)) when they are generated and calibrated according to the international regulations. The evaluation of the measurement uncertainty of a radioactive reference material with a natural half-life period is relevant and valid, considering its homogeneity properties and stability. To assess the properties, as well as the measurement uncertainty, one-variant variance analysis was performed.

Design of an Internet of Things (IoT)-Based Photosynthetically Active Radiation (PAR) Monitoring System

Photosynthetically Active Radiation (PAR) is an important parameter in the plant photosynthesis process, which can relate to plant growth, crop water use, and leaf gas exchange. Previously, many researchers utilized commercially available sensors to monitor PAR. The high cost of the commercially available PAR sensors has limited researchers, agricultural professionals, and farmers to use and expand PAR monitoring in agricultural lands. Thus, this paper focuses on designing an affordable Internet of Things (IoT)-based PAR sensor monitoring system including 3D-printed enclosures (waterproof) for the sensors, performance evaluation of multiple light sensors, solar powering configuration, cloud setup, and cost analysis. Three sensors, including VTB8440BH photodiode, SI 1145, and LI-190R sensors, were evaluated. The 3D-printed waterproof enclosures were designed for the photodiode and SI 1145. Particle Boron was used for recording and sending the sensor data to the IoT webserver. Both the photodiode and SI 1145 were compared to LI-190R, which is the industry standard. In the calibration process, the R2 values of the photodiode and SI 1145 with LI-190R were 0.609 and 0.961, respectively. Field validation data shows that SI 1145 had a strong correlation with LI-190R. In addition, the performance evaluation data shows the photodiode had a weaker correlation with LI-190R than SI 1145. In conclusion, the study successfully developed and designed affordable and reliable IoT-based PAR sensor monitoring systems, including a 3D-printed housing, hardware, programming, and IoT website. SI 1145 with a glass filter is an alternative sensor to monitor PAR at a low cost and has the advantage of being connected to IoT microcontrollers.

Synthesis of Al quantum dots on porous silicon as an effective radiation detector using extended gate technique

In this study, porous silicon (PS) and aluminum (Al) doped porous silicon were synthesized through an electrochemical method, utilizing carefully selected parameters. The etching procedure was calibrated with a 4:1 HF/ethanol ratio, maintaining a current of 20 mA for 20 min, and incorporating 0.05 g of doping powder. Comprehensive structural analysis using FESEM-EDX revealed the incorporation of Al into the porous silicon matrix. Subsequently, the samples were covered with a finger mask, which facilitated the creation of an interdigitated electrode using a sputtering deposition method. The I–V characteristics of the samples were systematically studied, showing an increase in bias voltage at the source correlated with the measured current. Remarkably, upon X-ray exposure, pulses were successfully measured, highlighting the potential of these materials for radiation detection. These pulses were evaluated under various X-ray irradiation parameters using a sample detector. The study successfully identified the optimal parameters for PS and Al-PS as (90 V, 100 mA, 1 s) and (100 V, 10 mA, 0.5 s), respectively. This research underscores the potential applications of these materials in advanced electronic devices and sensors. The unique properties of synthesized porous silicon, particularly when doped with aluminum, could be beneficial in areas such as photovoltaics, biosensors, and photonics. Additionally, the material's efficiency in detecting X-ray radiation suggests its suitability for medical imaging, security scanning, and radiation monitoring systems. Based on the I–V characteristic studies, these materials may be well-suited for use in electronic components requiring precise control of electrical properties. Overall, this study not only enhances our understanding of porous silicon and aluminum-doped porous silicon but also opens up new avenues for their application in a wide range of sensing technologies.

Development of a novel radiation monitoring system using a variable lofthole collimator

This study aims to develop a variable lofthole (VL) collimator-based gamma camera with a zoom function for detecting radioactive materials in radiation disaster situations. The VL collimator comprises seven layers, each forming a square hole with four tungsten (W) plates. Each layer of a W plate was controlled using four spur gears: external, internal, and rack gears. The VL collimator had a symmetrical structure. The detector was composed of a combination of a gadolinium aluminum gallium garnet scintillator doped with cerium (Ce:GAGG) and a silicon photomultiplier in the form of a two-dimensional array. In addition, a linear actuator was designed to enable precise forward and backward driving of the detector along with driving of the collimator to realize a magnification suitable for this purpose. The experimental results demonstrated that the full width at half maximum (FWHM) for the square hole size of 10 × 10 mm2 to 2 × 2 mm2 of the VL collimator at an acceptance angle of 45 ° decreased from 58.5 to 17.5 %, respectively. When the reception angle was reduced from 45 ° to 16 ° in a VL collimator with a square hole size of 3 × 3 mm2, the magnification increased by a factor of approximately 2.6. As the magnification increased, the spatial resolution improved, and it was confirmed that the two sources were well-distinguished. The results showed that the VL collimator-based gamma camera system designed in this study can be used to image radioactive materials with high sensitivity and resolution in radiation-related disaster situations.

Using Software Mitigation Schemes to improve the availability of IoT applications in harsh radiation environment

The integration of IoT infrastructure in the context of particle accelerators promises numerous benefits (reduced costs and maintenance time, increased deployment). However, the use of microcontroller units (MCUs), typical of IoT systems, can potentially compromise future accelerator availability performances. This paper presents Software Mitigation Schemes (SMS) designed to improve the availability performance of MCU-based systems under radiation. Their effectiveness is demonstrated through a radiation test on a CERN Wireless IoT Radiation Monitoring system, also called BatMon. The results underline the IoT devices' feasibility as a viable solution for high-distribution systems in the High-Luminosity Large Hadron Collider (HL-LHC) or Future Circular Collider (FCC).

Real-time radiation monitoring of high energy 1.2-GeV synchrotron accelerator using experimental physics and industrial control system

The high energy 1.2-GeV electron accelerator facility’s radiation detection and monitoring system (RDMS) has greatly evolved to be the effective backbone of real-time radiation monitoring for the new light source 3-GeV synchrotron facility. Experimental Physics and Industrial Control System (EPICS), ethernet hardware connections (Optic fibers), and Web-based software interfaces make up the new RDMS framework, built on well-liked network technology. The problems of monitoring i.e., a lot of manpower, poor monitoring accuracy, and inability to monitor continuously in the high radiation dose are eliminated. EPICS, composed of an Input/Output Controller (IOC) and Client Workstations which can communicate with a Local Area Network (LAN), were applied for remote control and radiation measurement. EPICS has been able to transport and store massive amounts of data for large-scale systems with a wide range and high accuracy. The monitoring data were sent to the server through the optic fibers network system, which is more advantages such as no distance restrictions, low attenuation of the signal, faster responding times, and particularly electromagnetic resistance. The data can be accessed anywhere from client monitors with graphical user interfaces. This system is successfully developed and tested for the high energy 1.2-GeV electron accelerator. The RDMS is useful for radiation safety to monitor the radiation dose level during machine operation to protect occupational workers and the public from radiation hazards.

Quality Control Analysis of Linear Accelerator Radiotherapy Device in the Department of Radiotherapy at Pasar Minggu District Hospital

Radiation accidents pose a significant risk, often stemming from inadequate calibration of radiation output, procedural lapses, and faults in radiation monitoring systems. Addressing these risks is pivotal, particularly in radiotherapy, where the precise functioning of linear accelerator (Linac) devices is crucial. This study delves into the quality control procedures applied to the Linac radiotherapy device within the Department of Radiotherapy at Pasar Minggu District Hospital. Drawing upon the renowned reference standards set by the AAPM Task Group 142 and BAPETEN Regulation No. K2N.2/MT-08, this research, conducted in November 2022, rigorously evaluated the mechanical, dosimetry, and safety aspects of the Linac device. The examination encompassed critical elements, including gantry angles, optical distance indicators, laser precision, collimator angles, light field size, and photon and electron beam outputs. Safety features such as door interlocks, audiovisual indicators, and radiation alert systems were scrutinized. The analysis reveals a reassuring finding: the Linac device at Pasar Minggu District Hospital adheres commendably to tolerance limits specified by reference standards across all measured parameters, indicating robust performance in mechanics, dosimetry, and safety. This meticulous quality control regimen has proven highly effective in ensuring the device's operational integrity and safety, affirming its reliability for precise radiotherapy treatments.

Development of recommendations for improving the radiation monitoring system of Ukraine

The effective functioning of the radiation monitoring network is an all-important task for all countries worldwide because the health of personnel working at radiation-hazardous facilities and the population living in the affected areas depend on it. A critical analysis of the functioning of radiation monitoring systems of various countries worldwide (Ukraine, United States of America, France, Sweden, Germany, South Korea, Switzerland, and China) was valid and showed their advantages and disadvantages. Criteria for displaying data on the electronic map about the state of radiation pollution and criteria for reports on the functioning of the radiation monitoring network have been determined. To improve the functioning of the radiation monitoring system of Ukraine, some recommendations for their improvement have been provided.

A Comprehensive Review on the Thermal Stability Assessment of Polymers and Composites for Aeronautics and Space Applications.

This review article provides an exhaustive survey on experimental investigations regarding the thermal stability assessment of polymers and polymer-based composites intended for applications in the aeronautical and space fields. This review aims to: (1) come up with a systematic and critical overview of the state-of-the-art knowledge and research on the thermal stability of various polymers and composites, such as polyimides, epoxy composites, and carbon-filled composites; (2) identify the key factors, mechanisms, methods, and challenges that affect the thermal stability of polymers and composites, such as the temperature, radiation, oxygen, and degradation; (3) highlight the current and potential applications, benefits, limitations, and opportunities of polymers and composites with high thermal stability, such as thermal control, structural reinforcement, protection, and energy conversion; (4) give a glimpse of future research directions by providing indications for improving the thermal stability of polymers and composites, such as novel materials, hybrid composites, smart materials, and advanced processing methods. In this context, thermal analysis plays a crucial role in the development of polyimide-based materials for the radiation shielding of space solar cells or spacecraft components. The main strategies that have been explored to improve the processability, optical transparency, and radiation resistance of polyimide-based materials without compromising their thermal stability are highlighted. The combination of different types of polyimides, such as linear and hyperbranched, as well as the incorporation of bulky pendant groups, are reported as routes for improving the mechanical behavior and optical transparency while retaining the thermal stability and radiation shielding properties. Furthermore, the thermal stability of polymer/carbon nanocomposites is discussed with particular reference to the role of the filler in radiation monitoring systems and electromagnetic interference shielding in the space environment. Finally, the thermal stability of epoxy-based composites and how it is influenced by the type and content of epoxy resin, curing agent, degree of cross-linking, and the addition of fillers or modifiers are critically reviewed. Some studies have reported that incorporating mesoporous silica micro-filler or microencapsulated phase change materials (MPCM) into epoxy resin can enhance its thermal stability and mechanical properties. The mesoporous silica composite exhibited the highest glass transition temperature and activation energy for thermal degradation among all the epoxy-silica nano/micro-composites. Indeed, an average activation energy value of 148.86 kJ/mol was recorded for the thermal degradation of unfilled epoxy resin. The maximum activation energy range was instead recorded for composites loaded with mesoporous microsilica. The EMC-5p50 sample showed the highest mean value of 217.6 kJ/mol. This remarkable enhancement was ascribed to the polymer invading the silica pores and forging formidable interfacial bonds.

Preliminary assessment of the radiological consequences of the hostile military occupation of the Chornobyl Exclusion Zone

The full-scale invasion of Ukraine by Russian military forces on 24 February 2022 put the radiological well-being of the people in Ukraine under unprecedented threat. Apart from the risks linked to operating nuclear power plants, there was substantial evidence of looting of facilities of all kinds, including those holding radioactive materials, as well as the scope for physical disturbance of radioactively contaminated areas and waste storage facilities. The actions of Russian military personnel invading Ukraine through the territory of the Chornobyl Exclusion Zone (the ChEZ) were of serious concern. Before its shutdown a few days after the beginning of the occupation, the automated radiation monitoring system of the ChEZ recorded sharp increases in the gamma-background in several areas which indicated some non-typical processes taking place on its territory. The State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) and its technical support organisation, the Scientific and Technical Centre for Nuclear and Radiation Safety (SSTC NRS), as well as the rest of the professional nuclear community in Ukraine and worldwide, recognised the potential for movement of the radioactive contamination (reaching 101–104 kBq m−2 Cs-137 in the most of the territory) by the Russian military machinery and personnel to areas outside the ChEZ, creating locally contaminated spots along the routes taken by the invaders towards Kyiv. Certain apprehensions were caused by the inventory carried out after the liberation of the ChEZ which revealed the theft of calibration sources and radioactive samples from laboratories located in Chornobyl. As soon as this information became available to the public, it caused a wide response and anxiety, as a result of which SNRIU made a decision to conduct a radiation survey of the liberated territories in the Kyiv region. The survey was conducted between June and December 2022 by SSTC NRS specialists with the support of DSA. The scope of the survey was limited by available time and resources; however, the total route of the survey was about 840 km, and covered more than 50 settlements and a limited part of the ChEZ. The radiation survey combined the continuous gamma-dose rate measurements by the detectors installed in the laboratory vehicle and additional manual measurements at specified points. As a result of the radiation survey, no deterioration of the radiation situation was observed in the liberated territories. No contaminated objects, radiation sources, or other radioactive material removed from the ChEZ were found either. Measurements of the Cs-137 soil contamination in the ChEZ, although limited, corresponded to the results which had been obtained before the war. It can be concluded that in the surveyed territories, the direct impact on the public in the form of additional radioactive contamination removed from the ChEZ in February-March 2022 was negligible. The same applies to the radiation consequences of forest fires that occurred in the ChEZ during its occupation. However, due to the damage of the radiation monitoring system, explosive hazard, and destruction of transport infrastructure, the consequences of the occupation of the ChEZ by Russian troops will be long-term.

RMS-R3 – the system for monitoring the region of interactions and background at the LHCB experiment (CERN)

The upgraded Large Hadron Collider beauty (LHCb) detector will provide data taken in Run3 at the instantaneous luminosity of proton-proton collisions increased to 2⋅1033 cm-2s-1 at energies of up to 14 TeV. To ensure the safe operation of the experiment, a new beam and background Radiation Monitoring System (RMS-R3) was built. RMS-R3 is based on metal-foil detector technology developed at the Institute for Nuclear Research, National Academy of Sciences of Ukraine (Kyiv, Ukraine). The system comprises four detector modules with two sensors in each. Their frequency response is proportional to the flux of incident charged particles. The modules are located around the beam pipe at a distance of 2.2 m from the interaction point. The results measured during the Run3 in 2022 testify to the reliable operation of the system. Applying the asymmetry method, high-accuracy data were obtained on the localization of the interactions region and the beam and background contribution.

Space weather monitoring with Health Canada’s terrestrial radiation monitoring network

This work presents a feasibility study of utilizing Health Canada’s terrestrial radiation monitoring network, the Fixed Point Surveillance (FPS) network, for space weather monitoring through demonstrating detections of Forbush decrease and ground level enhancement events. The network is currently comprised of more than eighty sodium iodide spectrometers distributed across Canada. It was designed for terrestrial radiation monitoring but is also capable of registering cosmic radiation in a high-energy channel. Data from fourteen FPS stations for the period from 2003 to 2018 were analyzed and compared with data obtained by other ground-level cosmic radiation monitoring systems. The level of atmospheric impacts on measurements can be well explained, and signatures of both long-term solar cycle variations and sporadic solar events have been detected in the FPS network. The Forbush decrease amplitudes in FPS were found to be comparable to those obtained in the global muon detector network but about 2–3 times lower than those recorded by the global neutron monitoring network. This study suggests that the 20 years of cosmic ray data from the FPS network can be used for climatological space weather studies. In addition, the network can be readily available for real-time space weather monitoring.

Investigation to design, fabricate, and integrate a mobile radiation monitoring system in ocean

Ocean radiation monitoring and warning systems are essential in monitoring radioactive species' contamination levels in an oceanic environment and predicting the radioactive materials propagation caused by nuclear incidents in a marine area. Since the Fukushima nuclear disaster, different types of mobile radiation monitoring devices have been investigated based on modern technologies in electronic – communication. Those types of equipment can directly measure the radioactive contamination in the ocean instead of the traditional laboratory method. This study presents a complete process of researching, designing, manufacturing, and integrating a mobile radiation monitoring system (MRMS) in the ocean. The integrated radiation sensor can both measure radiation dose rate and identify radioactive isotopes on a floating device. The measured data from the sensor is processed and displayed on the electronic block by developed software, or it can be transmitted directly to the mainland by one of three different communication devices. This prototype system is the first product in Vietnam in the development of the MRMS, which is highly promising in terms of performance, low cost, and maintenance.

Comparative study on gamma-ray detectors for in-situ ocean radiation monitoring system

Large-sized crystals and state-of-the-art photosensors are desirable to cope with low environmental radioactivity (e.g., 1–2 Bq∙m−3137Cs in surface seawater) for homeland security purposes. We compared the performances of two different gamma-ray detector assemblies, GAGG crystal + silicon photomultiplier (SiPM) and NaI(Tl) crystal + photomultiplier tube, for our mobile in-situ ocean radiation monitoring system. We performed energy calibration, followed by water tank experiments with varying the depth of a137Cs point source. Experimental energy spectra were compared with MCNP-simulated spectra with identical setup and the consistency was validated. We finally assessed the detection efficiency and minimum detectable activity (MDA) of the detectors. Both GAGG and NaI detectors exhibited favorable energy resolutions (7.98 ± 0.13% and 7.01 ± 0.58% at 662 keV, respectively) and MDAs (33.1 ± 0.0645 and 13.5 ± 0.0327 Bq∙m−3 for 24-h 137Cs measurement, respectively). Matching the geometry of the GAGG crystal with that of the NaI crystal, the GAGG detector outperformed the NaI detector. The results demonstrated that the GAGG detector is potentially advantageous over the NaI detector in detection efficiency and compactness.