Area Radiation Monitoring Research Articles

The importance of time-resolved personal Dosimetry in space: The ISS Crew Active Dosimeter

Monitoring space radiation is of vital importance for risk reduction strategies in human space exploration. Radiation protection programs on Earth and in space rely on personal and area radiation monitoring instruments. Crew worn radiation detectors are crucial for successful crew radiation protection programs since they measure what each crewmember experiences in different shielding configurations within the space habitable volume. The Space Radiation Analysis Group at NASA Johnson Space Center investigated several compact, low power, real-time instruments for personal dosimetry. Following these feasibility studies, the Crew Active Dosimeter (CAD) has been chosen as a replacement for the legacy crew passive radiation detectors. The CAD device, based on direct ion storage technology, was developed by Mirion Dosimetry Services to meet the specified NASA design requirements for the International Space Station (ISS) and Artemis programs. After a successful Technology demonstration on ISS, the CAD has been implemented for ISS Crew operations since 2020. The current paper provides an overview of the CAD development, ISS results and comparison with the ISS Radiation Assessment Detector (RAD) and the Radiation Environment Monitor 2 (REM2) instruments.

Overall design of radiation monitoring system formaritime nuclear facilities

The Radiation Monitoring System (RMS) is designed to check continuously the reactor at the operating set points, it assures that no individual and persons receive an unnecessary or hazardous exposure to radiation. According to the process and operation characteristics of Small Modular Reactor (SMR), these radiation monitoring channels can be grouped into the process radiation monitoring subsystem, the effluent radiation monitoring subsystem, the area radiation monitoring subsystem and the Post Accident Monitoring Subsystem (PAMS). Based on the architecture design of RMS, the demand of signal interface and power interface is analysed. Through introducing the marine environment, the problems of anti-shock, vibration, inclination and swing of loads are put forward.

Design, manufacture and deployment of a low-cost area radiation monitoring system using Raspberry Pi computers and open-source software.

Monitoring of background radiation levels in radiopharmaceutical laboratories is a key tool in minimising dose to workers. Retrofitting area monitoring systems in an existing laboratory can be disruptive and prohibitively expensive. We set out to develop a flexible low-cost area monitoring system utilising the power of inexpensive single board computers and open-source software. A complete system has been developed which includes local and remote real-time display with local warning, dose rate logging and automated plotting and backup of results from over 20 individual monitors connected via wifi.

Wireless Wide Area Radiation Monitoring Network Using Internet of Things

The nuclear disaster in Fukushima motivated the need for the development of a wireless wide area radiation monitoring network that is capable of measuring and remotely displaying radiation level in the affected zones without the concomitant increase in exposure of radiation to the workers. This paper describes the development of such a system using a commercially available Geiger-Mueller (GM) counter that can be deployed in a radiation-infested area. The GM counter transmits radiation readings at a fixed interval wirelessly to a web interface which is then shared in real time to remote stations. The proposed system employs the Internet of Things (IoT) platform, ThingSpeak, as an interface for sharing the information via the Internet. The system is modular as such that the number of stations can be readily added. The experimental results demonstrate that the proposed monitoring system is feasible for radiation monitoring.

Design and Development of Low-Cost, Highly Stable Regulated High-Voltage Power Supply for Radiation Detector

In this paper we design and develop a highly stable and low cost regulated DC power supply for Geiger Muller (GM) Counter/detector. A regulated high voltage power supply is an important power source to bias gasdischarge tubes, X-ray tubes, and radiation detectors etc. A highly stabilized regulated 575 volts DC power supply was developed using the pulse width modulation (PWM) control technique from a 5 volt supply. It is specially designed for biasing GM detector for the area radiation monitor. The output high voltage can be adjusted at any suitable value by adjusting the preset potentiometer.

Area radiation monitoring on ISS Increments 17 to 22 using PADLES in the Japanese Experiment Module Kibo

The measurement of radiation environmental parameters in space is essential to support radiation risk assessments for astronauts and establish a benchmark for space radiation models for present and future human space activities. The Japan Aerospace Exploration Agency (JAXA) is performing a continuous area radiation monitoring experiment using the “PAssive Dosimeters for Lifescience Experiments in Space” (PADLES) system inside the Japanese Experiment Module Kibo on board the International Space Station (ISS). The PADLES dosimeter consists of thermoluminescent dosimeters (TLDs) and CR-39 plastic nuclear track detectors (PNTDs). JAXA has run the Area PADLES experiment since the Kibo module was attached to the ISS in June 2008, using 17 dosimeters in fixed locations on the Pressurized Module (PM) and the Experiment Logistics Module-Pressurized Section (ELM-PS) of Kibo, which are replaced every 6 months or every Increment, respectively. For three monitoring periods, known as Area PADLES experiment series #1 to #3, of 301, 180, and 232 days in June 2008 to April 2010 over ISS Increments 17 to 22, the average absorbed dose (dose equivalent) rates of 12 positions in the PM of Kibo were 319 ± 30 μGy/day (618 ± 102 μSv/day), 276 ± 30 μGy/day (608 ± 94 μSv/day), and 293 ± 33 μGy/day (588 ± 84 μSv/day), respectively. The radiation measurement in the ELM-PS was conducted in only Area PADLES experiment series #3 from August 2009 to April 2010 (232 days) over ISS Increments 21 to 22, the average absorbed dose (dose equivalent) rates of 5 positions was 297 ± 28 μGy/day (661 ± 65 μSv/day). The directional dependence of the radiation field was also investigated by installing PADLES dosimeters located in the zenith of ELM-PS of Kibo.

Simulation Analysis of Ion Chambers for Area Radiation Monitoring System

KAERI (Korea Atomic Energy Research Institute) has been developing ion chambers which are used for an ares radiation monitoring system. Those ion chambers will be placed in the area where it is necessary to monitor radiatior dose all the time. The areas are nuclear plant site, research reactor site, radiation waste disposal site etc.. KAERI is developing a few different types of ion chambers for the above-mentioned purposes. One is an ion chamber having cylindrical shape with the active volume of ~1 l. Another one is also a cylindrical type ion chamber with the active volume of ~10 l. The smaller ion chamber of those 2 detectors will be installed in the place where a compact detectoi is required. Those ion chambers can be filled with gases such as air or Ar or Xe. The characteristics of those two ion chambers can be analyzed by simulation study. The simplified design of air-filled detectors (1.2 l and 13.7 l) was made and simulation study was performed by using the code EGSnrc. The energy of parallel radiation beam was varied from 50 keV to 1.5 MeV to analyze the expected ionization currents and dose as function of beam energy. The 100 keV and 1 MeV point source beams were adopted to investigate the angular dependence of radiation dose absorbed in the detector. We also investigated the change of characteristics of the 1.2 l ion chamber when the type oi filled gas is changed from air. The radiation dose was obtained for the cases of Ar and Xe. The same study was also performed when the pressurized air (2 bar) was filled in the detector.

Development of a New CdTe Area Radiation Monitor using the G(E) Function Method

We developed a small Area Radiation Monitor (ARM) prototype with high accuracy performance by combining a cadmium telluride (CdTe) detector with the G(E) function method. To obtain the measurement accuracy required for ARMs, we created a G(E) function based on detailed spectral responses. The accuracy of the derived dose rate and other expected requirements for practical applications were experimentally evaluated. The accuracy for a CdTe detector with dimensions of 5x5x5 mm3 was within 14% in the 60–300 keV range and within 10% in the 300 keV--1.8 MeV range, which was comparable to a large ARM with an ionization chamber. The accuracy for a CdTe detector with dimensions of 2x2x2mm3 was within 23% in the 60–300 keV range and within 14% in the 300 keV—1.8 MeV range, which was inferior to the 5x5x5 mm3 detector but higher than a small ARM using a silicon PIN photodiode.

Development of a New CdTe Area Radiation Monitor using the G(E) Function Method

Development of a New CdTe Area Radiation Monitor using the G(E) Function Method

Application of General Purpose Fiber Optic Data Links to Radiation Measurements

In order to take advantage of the inherent qualities of optical fiber, it is proposed to use fiber optic data links (FODLs) for radiation energy measurements. However, since an FODL is only capable of transmitting a digital signal, a technique must be implemented to convey the magnitude of the measured detector signals without a significant loss of fidelity. Two techniques were studied to convert pulse height signals into pulse width signals. In the first system (Method-1), conversion was carried out with a simple comparator circuit. Although the nonlinearity between the pulse height and the pulse width made the energy spectrum measurements difficult, the system's suitability for counting measurements was confirmed. The second system (Method-2) utilized a peak-detecting circuit and a constant-current circuit to make the conversion as linear as possible. By choosing appropriate field effect transistors (FETs), it was possible to measure the pulse height distribution above a gamma-ray energy of 0.2 MeV. The suitability of FODLs for radiation energy measurements was demonstrated with Method-2. In addition, both systems have the potential for multiplexed data collection by applying electrical or optical multiplexing techniques. When it is realozed, this can be a promising tool for wide area radiation monitoring.

Recent applications of microprocessor-based instruments in nuclear power stations

Safety-grade, microprocessor-based instruments and controllers for power plant applications called NUMAC (nuclear measurement, analysis, and control) are discussed. Their modular-based design has a common rack-mounted chassis with keypad and electroluminescent display and menu-driven operation under fixed program control. Past applications for NUMAC instruments and controllers are reviewed, and some instruments that are being installed in operating boiling-water reactors are described. These include instruments for area radiation monitoring, wide-range neutron monitoring, and rod worth minimization. Operating experience is reported. >

A Monte Carlo program to calculate the exposure rate from airborne radioactive gases inside a nuclear reactor containment building.

A program was developed to calculate the exposure rate resulting from airborne gases inside a reactor containment building. The calculations were performed at the location of a wall-mounted area radiation monitor. The program uses Monte Carlo techniques and accounts for both the direct and scattered components of the radiation field at the detector. The scattered component was found to contribute about 30% of the total exposure rate at 50 keV and dropped to about 7% at 2000 keV. The results of the calculations were normalized to unit activity per unit volume of air in the containment. This allows the exposure rate readings of the area monitor to be used to estimate the airborne activity in containment in the early phases of an accident. Such estimates, coupled with containment leak rates, provide a method to obtain a release rate for use in offsite dose projection calculations.

Area Radiation Monitor at the Intense Pulsed Neutron Source

A tissue-equivalent ionization chamber with associated circuitry has been developed for area radiation monitoring in the Intense Pulsed Neutron Source (IPNS) facility at Argonne National Laboratory. The conventional chamber configuration was modified in order to increase the electric field and effective volume thereby achieving higher sensitivity and linearity. Ihe instrument provides local and remote radiation level indications and a high level alarm. Twenty-four of these instruments were fabricated for use at various locations in the experimental area of the IPNS-1 facility.

Area Radiation Monitor System with Logarithmic Indication and Audio-Visual Warning

For five years a neutron detection system (utilizing BF3 detectors with moderators and vacuum tube amplifiers and count-rate circuits) has been in useful service at the Los Alamos large Van de Graaff accelerator. During this time difficulties with the need for increasing counting rate capability as well as component failures have led to a desire for improvement. In addition, the detectors were sensitive to thermal neutrons to an extent which made it difficult to get a legitimate measure of biological danger with various neutron spectra. An improved system was developed to give a more believable measure of biological danger (referred to "first collision tissue damage" described in NBS Handbook 633). The system was to be made more reliable through the minimization of vacuum tubes and relays. The problem of indicating varying levels of neutron flux without changing ranges was solved by a logarithmic count rate meter with a range from 1-5000 mrem/hour. The indicating system was to be expanded to give rapid visual information at the control room and other locations as well as audio alarms in the experimental area. By transistorizing all the electronic circuits and using only low voltages, both reliability and safety is improved. A gamma system, with a range from .01 to 10 r/hour, utilizing ionization chambers and an electrometer tube, is an integral part of the radiation system. It energizes the same alarm system as the neutron detectors. The system block diagram is shown in Fig. 1.