Confinement improvement during detached phase with RMP application in deuterium plasmas of LHD

In order to explore compatibility of good core plasma performance with divertor heat load mitigation, interaction between cold edge plasma and core plasma transport including edge transport barrier (ETB) has been analysed in the divertor detachment discharges of deuterium plasmas in LHD with RMP (resonant magnetic perturbation) field application. The RMP application introduces widened edge stochastic layer and sharp boundary in the magnetic field structure between the confinement region and the edge stochastic layer. The widened edge stochastic layer enhances impurity radiation and provides stable detachment operation as compared with the case without RMP. It is found that ETB is formed at the confinement boundary at the onset of detachment transition. However, as the detachment deepens resistive pressure gradient driven MHD mode is excited, which degrade the ETB. At the same time, however, the core transport decreases to keep global plasma stored energy (Wp) unchanged, showing clearly core-edge coupling. After gradual increase of density fluctuation during the MHD activity, spontaneous increase of Wp and recovery of ETB are observed while the detachment is maintained. Then the coherent MHD mode ceases and ELM like bursts appear. In the improved mode, the impurity decontamination occurs, and the divertor heat load increase slightly. Key controlling physics in the interplay between core and cold edge plasma is discussed. Comparison between deuterium and hydrogen plasmas show that the hydrogen plasmas exhibit similar features as the deuterium ones in terms of density and magnetic fluctuations, impurity decontamination toward higher confinement etc. But most of the features are modest in the hydrogen plasmas and thus no clear confinement mode transition with clear ETB formation is defined. Better global confinement is obtained in the deuterium plasmas than the hydrogen ones at higher radiation level.

Teresterial Background Ionizing Radiation around Lead/Zinc Mining Site in Ishiagu, Ebonyi State, Nigeria

Background ionizing radiation around Lead/Zinc mining sites at Ishiagu, Ebonyi State was carried out using appropriate equipment. The background ionizing radiation of the environment was determined by measuring the radiation exposure rates using Radalert-200 and Geographical Positioning System (GPS). Radiological health parameters and effective dose to different organs of the body was estimated. The average exposure rate of 0.00017mSv/h (0.017mR/h) measured was relatively higher than the world acceptable value of 0.00013mSv/h (0.013mR/h ). All the radiological risk parameters estimated are relatively high. The result of this work shows that the mining µactivities have enhanced the radiation level of Ishiagu and health status of the populace.

Natural Radionuclide Concentrations and Associated Doses Around Three Dumpsites in Lagos, Nigeria

Monitoring of environmental radiation helps to ascertain healthy vicinity which is a catalyst to the economic development of the area. Activity concentration of naturally occurring radionuclides in three (3) dumpsites in Lagos State, Olusosun Landfill, Ojota, Ilupeju dumpsite and, Gbagada dumpsite Lagos state, Nigeria were investigated using gamma-ray spectroscopy to obtain the level of radioactive exposure hazards experienced by people living in these vicinities. A total of thirty soil samples were randomly collected into a polythene bag. They were oven-dried at 110°C, pulverized, and sieved. Quantities of the samples (400 g) were sealed in cylindrical sample holders and kept for about 28 days to attain secular equilibrium between 226Ra and its decay products before analysis using gamma-ray spectrometry. The mean activity concentration obtained for 40K, 238U, and 234Th at, Ilupeju, Gbagada, and Ojota were 339.23±33.66, 11.83±19.174, 11.95±22.752 Bq/kg, 337.56 ± 36.22, 11.49±22.14, 11.54 ± 19.33 Bq/kg and 334.87±32.44, 11.42±22.39, 11.56±18.52 Bq/kg respectively. The mean absorbed dose nGy/h, annual effective dose mSv/y were calculated and their results were found to be below the global values. The results indicate that the radiation level within the dumpsites poses no significant health risk to the people living close to the dumpsites.

Development of a novel tool for automation of the contamination measurement

Considering that about 100 000 m2 of wall area per nuclear facility must be decontaminated (Hübner et al., 2017), the automation of mechanical decontamination work offers high potential to support people in performing their work and reduce errors in the decommissioning process. Furthermore, the exposure potential for people in contaminated environments is reduced and they are protected from health hazards (Petereit et al., 2019). In the ROBDEKON project, a competence center is being established in Germany to develop practical robotic systems for decontamination work in hazardous environments. To this end, four research institutions are working with industrial partners on the development of (partially) autonomous robotic systems for the decommissioning and decontamination of nuclear facilities, the handling of waste, and the remediation of landfills and contaminated sites (Petereit et al., 2019). At the Institute for Technology and Management in Construction (KIT-TMB), the focus is on development of an automated solution for the (clearance) measurement of near-surface contaminations. A mobile elevating working platform is used as the robotic platform with a contamination array as the tool. The array measures the surface activity on the wall areas and verifies compliance with the thresholds. The contamination array is based on two sensor concepts: measurement and localization. Up to four hand-held contamination-measuring devices are attached to the array to parallelize the measurement. In order to avoid damaging the sensitive detector window foil of the contamination probes, the wall surface to be measured is first examined for imperfections with the help of a laser scanner. For localization of the array, up to four laser sensors are used for distance measurements. Measurement results are automatically saved after each measurement in a table specific to the measurement method and are available to users for documentation purposes at any time. In the further course of the project, the measurement results depending on the radiation level will be overlaid with a geometric 3D environment mapping.

IMPLEMENTATION OF RADIATION MONITORING SYSTEM

Multiple atomic accidents urge for the development of radiation monitoring systems which has the capability to measure and display radiation level in the contaminated zones. This paper presents the design and implementation of such systems using Geiger Müller (GM) counter nuclear kit which can be used in any radiation contaminated area. GM counter transmits readings of radiation at fixed intervals to the Arduino microcontroller in real-time. This proposed system utilizes liquid crystal display (LCD) as an interface for displaying the information. This system is easy to use and modular. The experimental data and the obtained results shows that this proposed radiation monitoring system is feasible and efficient.

Diagnosis of Faults Induced by Radiation and Circuit-Level Design Mitigation Techniques: Experience from VCO and High-Speed Driver CMOS ICs Case Studies

In this paper, we discuss the diagnosis of particle-induced failures in harsh environments such as space and high-energy physics. To address these effects, simulation-before-test and simulation-after-test can be the key points in choosing which radiation hardening by design (RHBD) techniques can be implemented to mitigate or prevent failures. Despite the fact that total ionising dose (TID) has slow but destructive effects overtime on silicon devices, single-event effect (SEE) impulsively disrupts the typical operation of a circuit with temporary or permanent effects. The recently released SpaceFibre protocol drives the current requirements for space applications, and the future upgrade of the LHC experiment scheduled by CERN will require a redesign of the electronic front-end to sustain a radiation level up to the 1 Grad TID level. The effects that these two environments have on two different architectures for high-radiation and high-frequency data transmission are reported, and the efficiency of the mitigation techniques implemented, based on simulations and measurement tests, in the commercial 65 nm technology, are exploited.

Fault-Tolerant FPGA-Based Nanosatellite Balancing High-Performance and Safety for Cryptography Application

With the growth of the nano-satellites market, the usage of commercial off-the-shelf FPGAs for payload applications is also increasing. Due to the fact that these commercial devices are not radiation-tolerant, it is necessary to enhance them with fault mitigation mechanisms against Single Event Upsets (SEU). Several mechanisms such as memory scrubbing, triple modular redundancy (TMR) and Dynamic and Partial Reconfiguration (DPR), can help to detect, isolate and recover from SEU faults. In this paper, we introduce a dynamically reconfigurable platform equipped with configuration memory scrubbing and TMR mechanisms. We study their impacts when combined with DPR, providing three different execution modes: low-power, safe and high-performance mode. The fault detection mechanism permits the system to measure the radiation level and to estimate the risk of future faults. This enables the possibility of dynamically selecting the appropriate execution mode in order to adopt the best trade-off between performance and reliability. The relevance of the platform is demonstrated in a nano-satellite cryptographic application running on a Zynq UltraScale+ MPSoC device. A fault injection campaign has been performed to evaluate the impact of faulty configuration bits and to assess the efficiency of the proposed mitigation and the overall system reliability.

41Thyroid Cancers in Fukushima: Critical Review and Analysis of the 1st and 2nd Round Examination

Background After the Fukushima–Daiichi nuclear power plant (NPP) disaster, thyroid ultrasound examination (TUE) has been performed in subjects who were aged ≤18 years. Previous studies reported controversial results. Through critical review, three limitations were identified: arbitrary grouping of 59 municipalities, 2) usage of region as proxy of dose, and 3) separate analyse of the 1st and 2nd round data. Methods To overcome these limitations, this study examined the relationship between radiation dose and the number of participants with thyroid malignancy, using publicly available municipality level data (N = 59). To analyse two wave screening data, multi-level random-effect Poisson regression model was applied. The number of participants with thyroid malignancy was explained by dose estimates. Interaction between dose and screening round dummy (0 for the 1st and 1 for the 2nd) was also introduced to take into account latency. Results Interaction terms between external dose (Akahane et al. 2013) and screening round dummy were positive and significant (β = 0.681, z = 2.05). Similar results were obtained for UNSCEAR estimated thyroid dose (UNSCEAR 2013) (β = 0.128, z = 2.24) and re-estimated thyroid dose (Suzuki et al. 2018) (β = 0.215, z = 2.42). Conclusions These robust results are consistent with the conjecture that the 1st round TUE is the “baseline” that will not correlated with radiation level and the 2nd round TUE detected thyroid cancer caused by radiation from Fukushima NPP that distributed heterogeneously among regions. Key messages This was an ecological study at the municipality level, the results should be examined with individual level data.