Gamma Radiation Environment Research Articles

A gamma radiation scene image clarification method based on spatiotemporal combination

For the problems of complex noise and color cast in the images captured by complementary metal oxide semiconductor image sensors in the gamma radiation environment, this paper proposed a joint temporal correlation denoising and color cast correction approach for the gamma radiation scene image clarification. Concretely, we first adaptively stretch the difference between noise and background to improve the salience of weak noise, making noise detection results more accurate. Secondly, the temporal transient characteristics of gamma radiation noise are utilized for noise detection, and these noisy pixels are repaired by exploiting the temporal correlation characteristics of background pixels. Lastly, the Bayer-Guided auto white balance method is proposed to solve the problem of dysregulated color in the gamma radiation scene image, and the color level remapping approach is applied to eliminate the problem of insufficient dynamic range. Extensive experiments are carried out on the images captured from the Co60 gamma radiation scene. Compared with the source images, our method improves the peak signal to noise ratio by 6.3(dB) and structural similarity by 0.34. Experimental results demonstrate that the proposed method enjoys state-of-the-art performance in improving the clarity of gamma radiation scene images.

Gamma Radiation Image Noise Prediction Method Based on Statistical Analysis and Random Walk.

The gamma radiation environment is one of the harshest operating environments for image acquisition systems, and the captured images are heavily noisy. In this paper, we improve the multi-frame difference method for the characteristics of noise and add an edge detection algorithm to segment the noise region and extract the noise quantization information. A Gaussian mixture model of the gamma radiation noise is then established by performing a specific statistical analysis of the amplitude and quantity information of the noise. The established model is combined with the random walk algorithm to generate noise and achieve the prediction of image noise under different accumulated doses. Evaluated by objective similarity matching, there is no significant difference between the predicted image noise and the actual noise in subjective perception. The ratio of similarity-matched images in the sample from the predicted noise to the actual noise reaches 0.908. To further illustrate the spillover effect of this research, in the discussion session, we used the predicted image noise as the training set input to a deep residual network for denoising. The network model was able to achieve a good denoising effect. The results show that the prediction method proposed in this paper can accomplish the prediction of gamma radiation image noise, which is beneficial to the elimination of image noise in this environment.

High efficient low cost gamma-ray radiation sensor based on IoT platform

In the radiation sensing community, it's very important to detect gamma-ray radiation using remote sensing like IoT platforms. In this paper, high efficient low cost gamma-ray radiation sensor is designed to monitor and early detect radioactive materials that are present in the environment, and this is to be achieved based on IoT platform. Such platform provides a safer monitoring technique that helps avoiding the direct exposure to radiation and allows the exploration of inaccessible places. This paper conducts a deep informed study of N-channel (NMOS) and P-channel (PMOS) MOSFETs to be used as a dosimeter and sensor for gamma-ray radiation. The proposed technique herein uses the active load configuration of MOSFETs to detect the output current or the channel on resistance.MOSFET drain current and channel resistance values are changed based on variations of threshold voltage (VT) that are affected directly by the dose of absorbed gamma-ray radiation. For the purpose of sensing the ionizing radiation, the change ratios of output current or channel resistance values; due to threshold voltage shifting, are measured. A complete prototype of the proposed gamma-ray radiation IoT monitoring solution has been built and tested in a real gamma radiation environment over a dose range from 10 Gy up to 40 Gy. The highest current sensitivity of the proposed dosimeter was 0.579 mA/Gy and 0.529 mA/Gy for NMOS and PMOS respectively. The practical results show that the IoT monitoring radiation system is able to efficiently detect the gamma radiation remotely using low cost MOSFET transistors.

Investigation of the Combined Effect of Total Ionizing Dose and Time-Dependent Dielectric Breakdown on PDSOI Devices.

The combined effect of total ionization dose (TID) and time-dependent dielectric breakdown (TDDB) of partially depleted silicon-on-insulator (PDSOI) NMOSFET is investigated. First, the effect of TDDB on the parameter degradation of the devices was investigated by accelerated stress tests. It is found that TDDB stress leads to a decrease in off-state current, a positive drift in threshold voltage, and a reduction of maximum transconductance. Next, the degradation patterns of TID effect on the devices are obtained. The results show that the parameter degradation due to gamma radiation is opposite to the TDDB stress. Finally, the combined effect of TID and TDDB is investigated. It is found that the drift of the devices’ sensitive parameters due to TDDB stress decreases in a total dose of gamma radiation environment. The TDDB lifetime is shortened, but the pattern of gate current change remains unchanged. The failure mechanism of the gate oxide layer under TDDB stress is not changed after irradiation.

Study of the Sensing Characteristics of Irradiated Fiber Bragg Gratings and Fabry-Perot Interferometers Under Gamma Radiation

The sensing characteristics of irradiated fiber Bragg gratings (FBGs) and Fabry-Perot interferometers (FPIs) were investigated under a 2 MGy dose of gamma radiation. The study found that the pressure sensitivity of FP sensors after irradiation was stable, while the temperature sensitivity of FBG sensors was unstable, and both wavelengths displayed a shift. These findings offer the possibility for the application of FP pressure sensors in the gamma radiation environments, and FBG sensors require further research to be suitable for application in the nuclear radiation environments.

Investigating Heavy-Ion Effects on 14-nm Process FinFETs: Displacement Damage Versus Total Ionizing Dose

Bulk 14-nm FinFET technology was irradiated in a heavy-ion environment (42-MeV Si ions) to study the possibility of displacement damage (DD) in scaled technology devices, resulting in drive current degradation with increased cumulative fluence. These devices were also exposed to an electron beam, proton beam, and cobalt-60 source (gamma radiation) to further elucidate the physics of the device response. Annealing measurements show minimal to no “rebound” in the ON-state current back to its initial high value; however, the OFF-state current “rebound” was significant for gamma radiation environments. Low-temperature experiments of the heavy-ion-irradiated devices reveal increased defect concentration as the result for mobility degradation with increased fluence. Furthermore, the subthreshold slope (SS) temperature dependence uncovers a possible mechanism of increased defect bulk traps contributing to tunneling at low temperatures. Simulation work in Silvaco technology computer-aided design (TCAD) suggests that the increased OFF-state current is a total ionizing dose (TID) effect due to oxide traps in the shallow trench isolation (STI). The significant SS elongation and ON-state current degradation could only be produced when bulk traps in the channel were added. Heavy-ion irradiation on bulk 14-nm FinFETs was found to be a combination of TID and DD effects.

Design and analysis the operation of Schmitt trigger circuit in radiation environment

The object of research is the effect of gamma radiation on the characteristics of the operation amplifier, and consequently the behavior of the output voltage waveforms of Schmitt trigger circuit. One of the most problematic is the effect of the circuit elements, reference voltage, input frequency, input DC-voltage and bias voltage effects, on the operation of the proposed Schmitt trigger circuit. In the course of the research, the used Op Amp can be exposed to different types of radiation. As a result of the research it is shown that the threshold levels of Schmitt trigger circuit increased when operates in nuclear radiation environment.From the experimental work, computer simulation, and results analysis, the conclusions could be deduced, that Operation of operational amplifiers in gamma radiation environment show serious changes on their electrical characteristics. As a result, the Schmitt trigger circuit exposed to gamma radiation range from 3 kGy up to 20 kGy, at 10 Hz, where, its output voltage waveforms are shown to be independent on the gamma-dose. On the other hand, at frequency of 4.0 kHz, a severe effect are noticed, where the lower threshold level (VLTL) increase from –5.35 V up to –3.58 V, while the upper threshold voltage level (VUTL) is slightly increased from 4.21 V to 5 V, as a function of the same gamma doses. The obtained experimental results are shown to be in close agreement with those obtained from programming the Schmitt trigger equations to computer.In the future, the proposed approaches show that, whenever the Op Amp circuits are used in gamma radiation environment, it preferable to be operate at low frequency levels, where the output voltage waveform of Schmitt trigger circuit are shown to be independent on gamma dose but at high frequency the effect increased as a function of same gamma dose.

A Radiation-Tolerant Wireless Communication System for Severe Accident Monitoring Without Relying on Rad-Hardened Electronic Components

One of the most important considerations in the design of electronic systems for post-accident monitoring in a nuclear power plant is how to deal with the complex and uncertain radiation environments. Without using special design methodologies and adequate protection, nonradiation-hardened commercial-off-the-shelf (COTS) electronic components can easily be damaged. In this paper, a new design methodology is proposed so that COTS components can be used in building post-accident monitoring systems (PAMSs). To validate the effectiveness of the methodology, a prototype wireless post-accident monitoring system has been designed, implemented, and evaluated in a 60Co gamma radiation environment. It has been concluded that even at a dose rate of 20 krad (Si)/h, the prototype system operates satisfactorily even after being irradiated for 21 h. The system also operates satisfactorily at a low dose rate of 200 rad (Si)/h. It can be concluded that, even with COTS components, the proposed design can effectively extend the lifespan of post-accident monitoring systems in different radiation environments. Based on the experimental results, it can be said with confidence that the developed radiation-tolerant wireless monitoring system can operate for at least 8 h under the highest observed dose rate (530 Sv/h) encountered during the Fukushima Daiichi nuclear disaster and would have been able to provide crucial information to first responders following the accident.

An LTspice Simulation Model of Gamma-radiation Effects and Annealing in a Voltage Regulator With a Lateral Serial PNP Transistor With Round Emitters

The aim of this paper was to determine the reasons for a complex radiation response of the commercial-off-the-shelf LM2940CT5 low-dropout voltage regulator. Examination of this circuit in a gamma-radiation environment disqualified its use when operated with relatively high output currents, while its radiation tolerance was satisfactory when load current was approximately one-tenth (or lower) of the nominal value. In order to obtain a more thorough insight into the radiation response of this integrated circuit, a detailed SPICE model was developed. This model enabled mutual comparison of the influence of serial and driver PNP power transistor parameters: forward emitter current gain, knee current and emitter resistance. The serial lateral PNP power transistor with round emitters was identified as the weakest element that crucially affected the entire circuit radiation tolerance. The effects of gamma-radiation were examined for total doses up to 500 Gy followed by three sequences of isothermal annealing. Detailed characteristics of Beta(Ic) were procured for four different kinds of bias and load conditions during irradiation. The emitter resistance increase of the serial power transistor was a primary reason for the low radiation tolerance of the entire voltage regulator; it was much more influential than the perceived decline of the PNP power transistor forward emitter current gain. The influence of bias and load conditions were analysed with buildup of interface traps and the oxide-trapped charge, which affected the radiation and post-irradiation response of the serial power transistor.

Structural and optical studies of gamma irradiated N-doped 4H-SiC

In this paper, the gamma irradiation effects on the structural and optical properties of N-doped 4H-SiC (n-4H-SiC) is presented up to a cumulative gamma radiation dose of 1500 kGy. The studies showed marginal and inconsistent variation in the c- and a-axis lattice constants of 4H-SiC due to the accumulation of gamma-induced defect states. The modifications in the longitudinal optical plasmon-phonon coupled (LOPC) modes, Biedermann absorption bands, Urbach energy (EU) and defect related photoluminescence (DPL) bands are discussed at different (500, 1000 and 1500 kGy) irradiation doses. Despite these effects, the overall gamma-induced disorder (1-Anorm) and variation in the free carrier concentrations (n) are found to be negligible and demonstrating the radiation resistant property of n-4H-SiC under gamma radiation environment.

Digital neutron and gamma-ray radiography in high radiation environments with an MCP/Timepix detector

The radiation levels from used nuclear fuel make their post irradiation examination very difficult. Handling material removed from assemblies is almost exclusively performed inside shielded hot cells. Neutron radiography provides a non-destructive option for examining the internal structure, location and integrity of irradiated fuel. This paper addresses the performance and stability of a neutron imaging detector comprised of microchannel plates (MCPs) and a Timepix readout in gamma and neutron radiation environments. The detector is being considered as an alternative to the currently used activation foils and photographic film measurement techniques. The MCP/Timepix detector was used in neutron radiography experiment on a beam line at the Neutron Radiography Reactor (NRAD) at Idaho National Laboratory (INL). The detector was installed ∼17.5 m from the reactor core with a line of sight view to the core, which results in a fast and epithermal neutron spectrum as well as high intensity gamma radiation. The gamma-ray dose rate in the beam line was 812 mSv/hr. Complementary measurements were made using 137Cs and 60Co isotopic sources at gamma dose rates in excess of 6 Sv/hr. The detector functioned normally over several hours in this environment. These conditions are comparable to planned radiography of irradiated nuclear fuel assemblies. Experimental results using ASTM sensitivity and beam purity indicators suggest that a spatial resolution of <100 μm may be possible in neutron radiographic measurements using this detector for studies of irradiated nuclear fuel. Potential radiographic and tomographic applications are discussed. The results of present experiments are not limited to the studies of irradiated fuel assemblies, but rather are relevant to any experiment where imaging needs to be performed in a high radiation environment.

Progress Toward Rice Seed OMICS in Low-Level Gamma Radiation Environment in Iitate Village, Fukushima.

Here, we present an update on the next level of experiments studying the impact of the gamma radiation environment, created post-March, 2011 nuclear accident at Fukushima Daiichi nuclear power plant, on rice plant and its next generation-the seed. Japonica-type rice (Oryza sativa L. cv. Koshihikari) plant was exposed to low-level gamma radiation (~4 μSv/h) in the contaminated Iitate Farm field in Iitate village (Fukushima). Seeds were harvested from these plants at maturity, and serve as the treated group. For control group, seeds (cv. Koshihikari) were harvested from rice grown in clean soil in Soma city, adjacent to Iitate village, in Fukushima. Focusing on the multi-omics approach, we have investigated the dry mature rice seed transcriptome, proteome, and metabolome following cultivation of rice in the radionuclide contaminated soil and compared it with the control group seed (non-radioactive field-soil environment). This update article presents an overview of both the multi-omics approach/technologies and the first findings on how rice seed has changed or adapted its biology to the low-level radioactive environment.

Study on a Low-Cost and Large-Scale Environmentally Adaptive Protocol Stack of Nuclear and Space Wireless Sensor Network Applications Under Gamma Radiation

With the advancement of computer and communication technologies, wireless sensor networks (WSNs) are increasingly used in nuclear and space applications of radiation dose monitoring, earth observation, etc. In both cases, intensive radiation effects on electronic survivability are a concern. Gamma-ray damaging mechanisms in semiconductor devices are described as, and specifically linked to, semiconductor property changes in detectors, transistors, and integrated circuits. Radiation damage is cumulative and can result in the premature failure of WSN nodes. Thus, radiation-resistant electronics are commonly used for space and nuclear applications. However, these devices present a significant cost, especially when monitoring large areas. This paper focuses on studying a protocol stack that achieves an effective compromise in the cost and performance in a large-scale gamma radiation environment. The probability density function of a Weibull distribution is used to model failures of individual nodes in simulated WSNs. The distribution parameters are based on results of radiation-damage tests performed on semiconductor devices in the Gamma-220 facility (60Co source) at the Canadian Nuclear Laboratories (CNL). The simulation of the protocol stack proposed in this paper through network simulator 2 (NS2) and the resulting performance analyses could provide useful design insights and considerations for nuclear and space applications. Our work is the first study on designing an environmentally adaptive protocol stack in a large-scale gamma radiation environment for nuclear and space applications.

Evaluation of Distributed OFDR-Based Sensing Performance in Mixed Neutron/Gamma Radiation Environments

We report the study of a radiation resistant single mode optical fiber doped with fluorine exposed to mixed neutron and $\gamma $ -radiation up to $10^{17}$ n/cm2 fluence and >2 MGy dose to evaluate its performances when used as the sensing element of a distributed Optical Frequency Domain Reflectometry (OFDR). The use of complementary spectroscopic techniques highlights some differences between the responses of solely $\gamma $ -radiation (10 MGy) or mixed neutron and $\gamma $ ( $10^{17}$ n/cm $^{2}+>2$ MGy) irradiated samples. Those differences are linked to the defect generation rather than to structural changes of the ${a}$ -SiO2 host matrix. We show that a modification of the refractive index of $\sim 10^{\mathrm {-5}}$ is induced at the highest investigated neutron fluence. However, the feasibility of distributed temperature measurements along the irradiated fiber is demonstrated with an accuracy of 0.1 °C over a sensing length up to ~ 130 m with the tested OBR4600 interrogator. These results are very promising for the integration of OFDR sensors in mixed neutron and gamma radiation environments.

Effects of high energy radiation and thermo-chemical environments on polyetherimide composites: futuristic approach to nuclear waste storage

This research highlights the effect of radiation, chemical and thermal environments on mechanical and thermal properties of polyetherimide (PEI) composites. The tests are conducted on specimens made from PEI and PEI reinforced with modified Carbon Nano Fibre (CNF). The specimens are subjected to gamma radiation doses of 5 MGy, which is equivalent to the cumulative dose of radiation from spent nuclear fuel until the end of complete radioactivity. The exposed samples are further subjected to highly corrosive and thermal environments. Studies under transmission electron microscopy reveal that there is a uniform dispersion of modified CNF in PEI. Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) indicate that there are no significant changes in thermal properties of PEI and PEI composite when exposed to aggressive environments. It is observed that there is a marginal loss in the tensile strength of polymeric samples when exposed to gamma radiation and thermal environments. PEI samples when subjected to alkaline corrosive environments show significant loss in the tensile strength. There is a significant decrease in the molecular weight of PEI under alkaline corrosive environments as seen from Gel Permeable Chromatography (GPC).

Examination of scintillator-photovoltaic cell-based spent fuel radiation energy conversion for electricity generation

Using computational models, this research examined electricity generation from spent nuclear fuel and its possible uses. The proposed approach was based on converting gamma radiation energy into electricity using scintillators and photovoltaic cells. The work includes performing gamma radiation environment analysis around spent fuel, scintillated photon analysis, and photovoltaic cell analysis for electricity generation. The OrigenArp code was used for gamma radiation environment analysis and the MCNPX 2.7.0 code was used for analyzing scintillation process. For the scintillated photon analysis and photovoltaic cell analysis, a new simulation model was developed and validated based on comparison with experimental data. The effect of self-absorption and radiation damage within the scintillator was described by using experimental data. Based on using 14 energy conversion system units in a spent fuel storage pool in a PWR with CdWO4 as scintillator and SiO2 as photovoltaic cell, generation of electric energy was estimated to range between a few hundred watts and a few watts depending on the cooling time. The estimated amount of electric power generation from spent fuel energy conversion was not enough for large scale applications. But the converted electric power could be utilized as emergency power source in an operating nuclear power plant for various detection and monitoring purposes and for the support of spent fuel pool cooling pump operations.

Feasibility of polyetherketone (PEK) composites: a solution for long-term nuclear waste storage

This investigation highlights the effect of radiation, chemical and thermal environments on mechanical and thermal properties of polyetherketone (PEK) composites and its rationale for long-term nuclear waste storage. The tests are conducted on samples manufactured using PEK and PEK reinforced with modified carbon nano fibre (CNF). The specimens are subjected to gamma radiation doses of 5 MGy, which is equivalent to the cumulative dosage of radiation from spent nuclear fuel until the radioactivity neutralises completely. Studies under transmission electron microscopy (TEM) reveal that there is a uniform dispersion of modified CNF in PEK. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicate that there are no significant changes in thermal properties of PEK and PEK composite when exposed to aggressive environments. It is observed that tensile strength of polymeric samples remains unchanged when exposed to gamma radiation and thermo-chemical environment.

In Situ Gamma Radiation‐Induced Attenuation in Sapphire Optical Fibers Heated to 1000°C

The purpose of this work was to determine the suitability of using instrumentation utilizing sapphire optical fibers in a high‐temperature gamma radiation environment. In this work, the broadband (500–2200 nm, or 0.56–2.48 eV) optical attenuation of commercially available sapphire optical fibers was monitored in situ during continuous gamma irradiation from room temperature up to 1000°C. The gamma dose rate of the irradiation facility was measured to be 370 rad/h (dose in sapphire). Results show rapid growth of an absorption band centered below 500 nm (the minimum detectable wavelength in this work) and extending as far as ~1000 nm that reached a dynamic equilibrium after approximately 4 h of irradiation at room temperature. Increasing temperature generally reduced the added attenuation, although the added attenuation came to a nonzero equilibrium at temperatures of 1000°C and below. No peaks in the added attenuation were observed above 1000 nm, and the added attenuation at 1300 and 1550 nm remained less than 0.7 dB throughout the entire experiment. Fitting the attenuation spectra to Gaussian functions at each temperature revealed a large absorption band near 3 eV that monotonically decreased both in magnitude and width with increasing temperature. A second smaller band near 1.73 eV monotonically increased in both magnitude and width with increasing temperature, suggesting that some interconversion between defects may be occurring at higher temperatures.

Range-Finding Sensor Degradation in Gamma Radiation Environments

The effects of gamma radiation on common sensors used in robots intended for nuclear remediation scenarios are examined. Commercial rangefinders are chosen as an exemplar of the impact of gamma radiation on sensors and systems. This paper illustrates sensor radiation degradation not only in operational failure, but also in changes in the sensor transfer function. Three types of commercial range-finding sensors are considered [infrared (IR) triangulation using a position sensitive detector, sonar using time of flight, and laser rangefinder using triangulation and a CMOS camera]. Experimental results show significant changes in the IR sensor’s static sensitivity with dose, abrupt failure of the laser range finder at low dose, and degradation and abrupt failure for the sonar detector. The input–output relationship of the IR sensor showed further variation after a period of room-temperature annealing. Significant part-to-part variation in radiation response is shown for both the sonar and IR sensor. System level impacts due to sensor input–output relationship degradation and a technique to diagnose the degradation extendable to more complex sensor assemblies are presented.

Failure of the negative voltage regulator in medium-photon-energy X radiation fields

Negative voltage regulators were examined in the effective 60-keV and 170-keV bremsstrahlung fields, as well as in the field of 60Co gamma-radiation. Most devices irradiated in the fields of medium-dose-rate breaking radiation failed to operate after absorption of very small total doses of ionizing radiation, in the range of 37–132Gy(SiO2). However, all samples irradiated in the gamma radiation environment remained completely functional, even after deposition of a total dose of 500Gy(SiO2). Devices irradiated with higher input voltages failed after absorption of low total doses, whereas the load current increase mitigated and even prevented circuit failures in X radiation fields. The high radiation sensitivity of the LM2990T-5 voltage regulators operating in the bremsstrahlung fields was a consequence of the dose enhancement on the gold–aluminum connection between the silicon chip and ground contact. Computer model simulations indicated that the primary failure mechanisms were the generation of radiation-induced leakage currents alongside the npn transistors in the operational amplifier circuit. The difference between the voltage regulator responses in various bremsstrahlung environments was affected by the time-dependent effects, leading to the partial recovery of radiation-induced trapped charge.