• 제목/요약/키워드: Work-Net

검색결과 1,105건 처리시간 0.026초

Study on volume reduction of radioactive perlite thermal insulation waste by heat treatment with potassium carbonate

  • Chou, Yi-Sin;Singh, Bhupendra;Chen, Yong-Song;Yen, Shi-Chern
    • Nuclear Engineering and Technology
    • /
    • 제54권1호
    • /
    • pp.220-225
    • /
    • 2022
  • Perlite is one of the major constituents of the radioactive thermal insulation waste (RTIW) originating from nuclear power plants and, for proper waste management, a significant reduction in its volume is required prior to disposal. In this work, the volume reduction of perlite is studied by high-temperature treatment method with using K2CO3 as a flux. The perlite is ground with 0-30 wt% K2CO3, and differential thermal analysis/thermogravimetric analysis is used to monitor the glass transition temperature (Tg) and weight loss. The Tg varied between ~772.2 and 837.1 ℃ with the minima at ~643.5 ℃ with the addition of ~10 wt% K2CO3. It is observed that compared to the pure perlite the volume reduction ratio (VRR) increases with the addition of K2CO3. The VRR of 11.20 is observed with 5 wt% K2CO3 at 700 ℃, as compared to VRR of 5.56 without K2CO3 at 700 ℃. The X-ray photoelectron spectroscopy and scanning electron microscopy are used to characterize perlite samples heat-treated without/with 5 wt% K2CO3 at 700 ℃. Moreover, the atomic absorption spectroscopy indicates that the proposed heat-treatment procedure is able to completely retain the radionuclides present in the perlite RTIW.

Experimental investigation on the degradation of SiGe LNAs under different bias conditions induced by 3 MeV proton irradiation

  • Li, Zhuoqi;Liu, Shuhuan;Ren, Xiaotang;Adekoya, Mathew Adefusika;Zhang, Jun;Liu, Shuangying
    • Nuclear Engineering and Technology
    • /
    • 제54권2호
    • /
    • pp.661-665
    • /
    • 2022
  • The 3 MeV proton irradiation effects on SiGe low noise amplifier (LNA) (NXP BGU7005) performance under different voltage supply VCC (0 V, 2.5 V) conditions were firstly experimental studied in this present work. The S parameters including S11, S22, S21, 1 dB compression point and noise figure (NF) of the test samples under different bias voltage supply were measured and compared before and after 3 MeV proton irradiation. The total proton irradiation fluence was 1 × 1015 protons/cm2. The maximum degradation quantities of the gain S21 and NF of the test samples under zero bias are measured respectively 1.6 dB and 1.2 dB. Compared with the samples under 2.5 V bias supply, the maximum degradation of S21 and NF are respectively 1.1 dB and 0.8 dB in the whole frequency band. It is noteworthy that the gain and NF of SiGe LNAs under zero-bias mode suffer enhanced degradation compared with those under normal bias supply. The key influence factors are discussed based on the correlation of the SiGe device and the LNA circuit. Different process of the ionization damage and displacement damage under zero-bias and 2.5 V bias voltage supply contributed to the degradation difference. The underlying physical mechanisms are analyzed and investigated.

Deuterium ion irradiation impact on the current-carrying capacity of DI-BSCCO superconducting tape

  • Rajput, M.;Swami, H.L.;Kumar, R.;Bano, A.;Vala, S.;Abhangi, M.;Prasad, Upendra;Kumar, Rajesh;Srinivasan, R.
    • Nuclear Engineering and Technology
    • /
    • 제54권7호
    • /
    • pp.2586-2591
    • /
    • 2022
  • In the present work, we have irradiated the DI-BSCCO superconducting tapes with the 100 keV deuterium ions to investigate the effect of ion irradiation on their critical current (Ic). The damage simulations are carried out using the binary collision approximation method to get the spatial distribution and depth profile of the damage events in the high temperature superconducting (HTS) tape. The point defects are formed near the surface of the HTS tape. These point defects change the vortex profile in the superconducting tape. Due to the long-range interaction of vortices with each other, the Ic of the tape degrades at the 77 K and self magnetic field. The radiation dose of 2.90 MGy degrades the 44% critical current of the tape. The results of the displacement per atom (dpa) and dose deposited by the deuterium ions are used to fit an empirical relation for predicting the degradation of the Ic of the tape. We include the dpa, dose and columnar defect terms produced by the incident particles in the empirical relation. The fitted empirical relation predicts that light ion irradiation degrades the Ic in the DI-BSCCO tape at the self field. This empirical relation can also be used in neutron irradiation to predict the lifetime of the DI-BSCCO tape. The change in the Ic of the DI-BSCCO tape due to deuterium irradiation is compared with the other second-generation HTS tape irradiated with energetic radiation.

Representative Batch Normalization for Scene Text Recognition

  • Sun, Yajie;Cao, Xiaoling;Sun, Yingying
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • 제16권7호
    • /
    • pp.2390-2406
    • /
    • 2022
  • Scene text recognition has important application value and attracted the interest of plenty of researchers. At present, many methods have achieved good results, but most of the existing approaches attempt to improve the performance of scene text recognition from the image level. They have a good effect on reading regular scene texts. However, there are still many obstacles to recognizing text on low-quality images such as curved, occlusion, and blur. This exacerbates the difficulty of feature extraction because the image quality is uneven. In addition, the results of model testing are highly dependent on training data, so there is still room for improvement in scene text recognition methods. In this work, we present a natural scene text recognizer to improve the recognition performance from the feature level, which contains feature representation and feature enhancement. In terms of feature representation, we propose an efficient feature extractor combined with Representative Batch Normalization and ResNet. It reduces the dependence of the model on training data and improves the feature representation ability of different instances. In terms of feature enhancement, we use a feature enhancement network to expand the receptive field of feature maps, so that feature maps contain rich feature information. Enhanced feature representation capability helps to improve the recognition performance of the model. We conducted experiments on 7 benchmarks, which shows that this method is highly competitive in recognizing both regular and irregular texts. The method achieved top1 recognition accuracy on four benchmarks of IC03, IC13, IC15, and SVTP.

Physics-based modelling and validation of inter-granular helium behaviour in SCIANTIX

  • Giorgi, R.;Cechet, A.;Cognini, L.;Magni, A.;Pizzocri, D.;Zullo, G.;Schubert, A.;Van Uffelen, P.;Luzzi, L.
    • Nuclear Engineering and Technology
    • /
    • 제54권7호
    • /
    • pp.2367-2375
    • /
    • 2022
  • In this work, we propose a new mechanistic model for the treatment of helium behaviour at the grain boundaries in oxide nuclear fuel. The model provides a rate-theory description of helium inter-granular behaviour, considering diffusion towards grain edges, trapping in lenticular bubbles, and thermal resolution. It is paired with a rate-theory description of helium intra-granular behaviour that includes diffusion towards grain boundaries, trapping in spherical bubbles, and thermal re-solution. The proposed model has been implemented in the meso-scale software designed for coupling with fuel performance codes SCIANTIX. It is validated against thermal desorption experiments performed on doped UO2 samples annealed at different temperatures. The overall agreement of the new model with the experimental data is improved, both in terms of integral helium release and of the helium release rate. By considering the contribution of helium at the grain boundaries in the new model, it is possible to represent the kinetics of helium release rate at high temperature. Given the uncertainties involved in the initial conditions for the inter-granular part of the model and the uncertainties associated to some model parameters for which limited lower-length scale information is available, such as the helium diffusivity at the grain boundaries, the results are complemented by a dedicated uncertainty analysis. This assessment demonstrates that the initial conditions, chosen in a reasonable range, have limited impact on the results, and confirms that it is possible to achieve satisfying results using sound values for the uncertain physical parameters.

Comparative optimization of Be/Zr(BH4)4 and Be/Be(BH4)2 as 252Cf source shielding assemblies: Effect on landmine detection by neutron backscattering technique

  • Elsheikh, Nassreldeen A.A.
    • Nuclear Engineering and Technology
    • /
    • 제54권7호
    • /
    • pp.2614-2624
    • /
    • 2022
  • Monte Carlo simulations were used to model a portable Neutron backscattering (NBT) sensor suitable for detecting plastic anti-personnel mines (APMs) buried in dry and moist soils. The model consists of a 100 MBq 252Cf source encapsulated in a neutron reflector/shield assembly and centered between two 3He detectors. Multi-parameter optimization was performed to investigate the efficiency of Be/Zr(BH4)4 and Be/Be(BH4)2 assemblies in terms of increasing the signal-to-background (S/B) ratio and reducing the total dose equivalent rate. The MCNP results showed that 2 cm Be/3 cm Zr(BH4)4 and 2 cm Be/3 cm Be(BH4)2 are the optimal configurations. However, due to portability requirements and abundance of Be, the 252Cf-2 cm Be/3 cm Be(BH4)2 NBT model was selected to scan the center of APM buried 3 cm deep in dry and moist soils. The selected NBT model has positively identified the APM with a S/B ratio of 886 for dry soils of 1 wt% hydrogen content and with S/B ratios of 615, 398, 86, and 12 for the moist soils containing 4, 6, 10, and 14 wt% hydrogen, respectively. The total dose equivalent rate reached 0.0031 mSv/h, suggesting a work load of 8 h/day for 806 days within the permissible annual dose limit of 20 mSv.

Theoretical simulation on evolution of suspended sodium combustion aerosols characteristics in a closed chamber

  • Narayanam, Sujatha Pavan;Kumar, Amit;Pujala, Usha;Subramanian, V.;Srinivas, C.V.;Venkatesan, R.;Athmalingam, S.;Venkatraman, B.
    • Nuclear Engineering and Technology
    • /
    • 제54권6호
    • /
    • pp.2077-2083
    • /
    • 2022
  • In the unlikely event of core disruptive accident in sodium cooled fast reactors, the reactor containment building would be bottled up with sodium and fission product aerosols. The behavior of these aerosols is crucial to estimate the in-containment source term as a part of nuclear reactor safety analysis. In this work, the evolution of sodium aerosol characteristics (mass concentration and size) is simulated using HAARM-S code. The code is based on the method of moments to solve the integro-differential equation. The code is updated to FORTRAN-77 and run in Microsoft FORTRAN PowerStation 4.0 (on Desktop). The sodium aerosol characteristics simulated by HAARM-S code are compared with the measured values at Aerosol Test Facility. The maximum deviation between measured and simulated mass concentrations is 30% at initial period (up to 60 min) and around 50% in the later period. In addition, the influence of humidity on aerosol size growth for two different aerosol mass concentrations is studied. The measured and simulated growth factors of aerosol size (ratio of saturated size to initial size) are found to be matched at reasonable extent. Since sodium is highly reactive with atmospheric constituents, the aerosol growth factor depends on the hygroscopic growth, chemical transformation and density variations besides coagulation. Further, there is a scope for the improvement of the code to estimate the aerosol dynamics in confined environment.

A novel barium oxide-based Iraqi sand glass to attenuate the low gamma-ray energies: Fabrication, mechanical, and radiation protection capacity evaluation

  • Al-Saeedi, F.H.F.;Sayyed, M.I.;Kapustin, F.L.;Al-Ghamdi, Hanan;Kolobkova, E.V.;Tashlykov, O.L.;Almuqrin, Aljawhara H.;Mahmoud, K.A.
    • Nuclear Engineering and Technology
    • /
    • 제54권8호
    • /
    • pp.3051-3058
    • /
    • 2022
  • In the present work, untreated Iraqi sand with grain sizes varied between 100 and 200 ㎛ was used to produce a colored glass sample that has shielding features against the low gamma-ray energy. Therefore, a weight of 70-60 wt % sand was mixed with 9-14 wt% B2O3, 8-10 wt% Na2O, 4-6 wt% of CaO, 3-6 wt% Al2O3, in addition to 0.3% of Co2O3. After melting and annealing the glass sample, the X-ray diffraction spectrometry was applied to affirm the amorphous phase of the fabricated glass samples. Moreover, the X-ray dispersive energy spectrometry was used to measure the chemical composition, and the MH-300A densimeter was applied to measure the fabricated sample's density. The Makishima-Makinzie model was applied to predict the mechanical properties of the fabricated glass. Besides, the Monte Carlo simulation was used to estimate the fabricated glass sample's radiation shielding capacity in the low-energy region between 22.1 and 160.6 keV. Therefore, the simulated linear attenuation coefficient changed between 10.725 and 0.484 cm-1, raising the gamma-ray energy between 22.1 and 160.6 keV. Also, other shielding parameters such as a half-value layer, pure lead equivalent thickness, and buildup factors were calculated.

FPGA integrated IEEE 802.15.4 ZigBee wireless sensor nodes performance for industrial plant monitoring and automation

  • Ompal, Ompal;Mishra, Vishnu Mohan;Kumar, Adesh
    • Nuclear Engineering and Technology
    • /
    • 제54권7호
    • /
    • pp.2444-2452
    • /
    • 2022
  • The field-programmable gate array (FPGA) is gaining popularity in industrial automation such as nuclear power plant instrumentation and control (I&C) systems due to the benefits of having non-existence of operating system, minimum software errors, and minimum common reason failures. Separate functions can be processed individually and in parallel on the same integrated circuit using FPGAs in comparison to the conventional microprocessor-based systems used in any plant operations. The use of FPGAs offers the potential to minimize complexity and the accompanying difficulty of securing regulatory approval, as well as provide superior protection against obsolescence. Wireless sensor networks (WSNs) are a new technology for acquiring and processing plant data wirelessly in which sensor nodes are configured for real-time signal processing, data acquisition, and monitoring. ZigBee (IEEE 802.15.4) is an open worldwide standard for minimum power, low-cost machine-to-machine (M2M), and internet of things (IoT) enabled wireless network communication. It is always a challenge to follow the specific topology when different Zigbee nodes are placed in a large network such as a plant. The research article focuses on the hardware chip design of different topological structures supported by ZigBee that can be used for monitoring and controlling the different operations of the plant and evaluates the performance in Vitex-5 FPGA hardware. The research work presents a strategy for configuring FPGA with ZigBee sensor nodes when communicating in a large area such as an industrial plant for real-time monitoring.

Influence of operation of thermal and fast reactors of the Beloyarsk NPP on the radioecological situation in the cooling pond. Part 1: Surface water and bottom sediments

  • Panov, Aleksei;Trapeznikov, Alexander;Trapeznikova, Vera;Korzhavin, Alexander
    • Nuclear Engineering and Technology
    • /
    • 제54권8호
    • /
    • pp.3034-3042
    • /
    • 2022
  • The results of radioecological monitoring of the cooling pond Beloyarsk NPP (Russia) have been presented. The influence of waste technological waters of thermal and fast NPP reactors on the content of artificial radionuclides in surface waters and bottom sediments of the Beloyarsk reservoir has been studied. The long-term dynamics of the specific activity of 60Co, 90Sr, 137Cs and 3H in the main components of the freshwater ecosystem at different distances from the source of radionuclide discharge has been estimated. Critical radionuclides (60Co and 137Cs), routes of their entry and periods of maximum discharge of radioisotopes into the cooling pond have been determined. It is shown that the technology of electricity generation at Beloyarsk NPP, based on fast reactors, has a much smaller effect on the flow of artificial radionuclides into the freshwater ecosystem of the reservoir. During the entire period of monitoring studies, the decrease in the specific activity of radionuclides from NPP origin in surface waters was 4.3-74.5 times, in bottom sediments 10-505 times. The maximum discharge of artificial radionuclides into the reservoir was noted during the period of restoration and decontamination work aimed at eliminating emergencies at the AMB thermal reactors of the first stage of the Beloyarsk NPP.