bluuebunny/crossref_metadata_2025 huggingface dataset:
CRISPR‐BETS: a base‐editing design tool for generating stop codons
Authors: Wu Yuechao , He Yao , Sretenovic Simon , Liu Shishi , Cheng Yanhao , Han Yangshuo , Liu Guanqing , Bao Yu , Fang Qing , Zheng Xuelian , Zhou Jianping , Qi Yiping , Zhang Yong , Zhang Tao
Published: October 2021

Cytosine base editors (CBEs) can install a predefined stop codon at the target site, representing a more predictable and neater method for creating genetic knockouts without altering the genome size. Due to the enhanced predictability of the editing outcomes, it is also more efficient to obtain homozygous mutants in the first generation. With the recent advancement of CBEs on improved editing activity, purify and specificity in plants and animals, base editing has become a more appealing technology for generating knockouts. However, there is a lack of design tools that can aid the adoption of CBEs for achieving such a purpose, especially in plants. Here, we developed a user‐friendly design tool named CRISPR‐BETS (base editing to stop), which helps with guide RNA (gRNA) design for introducing stop codons in the protein‐coding genes of interest. We demonstrated in rice and tomato that CRISPR‐BETS is easy‐to‐use, and its generated gRNAs are highly specific and efficient for generating stop codons and obtaining homozygous knockout lines. While we tailored the tool for the plant research community, CRISPR‐BETS can also serve non‐plant species.
Introduction of the Effective Photon Concentration Variable for Studying the Mechanism of Crystal Violet Photodegradation
Authors: Arabameri Mojtaba , Bashiri Hadis
Published: October 2021

In this work, we have proposed a new approach to study the mechanism of crystal violet (CV) photodegradation on TiO2 surface using kinetic Monte Carlo simulation. The TiO2 surface was considered as a set of reactive centers, which is essential in dye photodegradation. A new variable "the effective photon concentration" (Ieff) is defined. A detailed chemical understanding of the photocatalytic reaction is provided. This approach provides a simple and effective method to find the optimal conditions of the studied system. This goal was achieved by investigating the effects of some operational parameters, including initial concentration of CV, pH, loading TiO2, light intensity and volume, on the degradation percent, and also, on the effective photon concentration. The perfect agreements between the experimental and simulated data at different conditions confirmed the proposed approach for describing the CV photodestruction. Also, the simulation results indicated that: (1) a significant fraction of the scattered UV irradiation into the reaction vessel does not lead to charge carrier generation; (2) the generation and recombination of charge carriers have crucial roles in the photodegradation. This is the first time that a method based on the reactive centers is employed to investigate the dye degradation by a photocatalyst.
ASMTL‐AS1 impedes the malignant progression of lung adenocarcinoma by regulating SAT1 to promote ferroptosis
Authors: Sui Xiujie , Hu Na , Zhang Ze , Wang Yirong , Wang Pengbo , Xiu Guanghong
Published: October 2021

Lung adenocarcinoma (LUAD) is difficult to cureradically. Long non‐coding RNAs (lncRNAs) in LUAD are a hotspot in molecular research, however, the role of lncRNA ASMTL‐AS1 in LUAD is still unknown. Our study explores the role and mechanisms of ASMTL‐AS1 in LUAD. Quantitative reverse transcription PCR or western blot was utilized to analyze the expression of RNAs or proteins. The influences of ASMTL‐AS1 and SAT1 on LUAD cells were analyzed by functional assays. Biological instruments were applied to observe ferroptosis‐related markers. In vivo assays were performed to uncover the impact of ASMTL‐AS1 on LUAD. Moreover, mechanism assays were done to confirm the relationship among ASMTL‐AS1, SAT1 and U2AF2. Results showed that ASMTL‐AS1 was down‐regulated in LUAD cells and ASMTL‐AS1 up‐regulation resulted in retarded LUAD cell and xenograft tumor growth along with stimulated ferroptosis. ASMTL‐AS1 recruited U2AF2 to stabilize SAT1 mRNA. Furthermore, SAT1 exerted a cancer suppressor role in LUAD cells. In conclusion, we first demonstrated that ASMTL‐AS1 positively regulated SAT1 to promote ferroptosis and could stabilize SAT1 mRNA via recruiting U2AF2, shedding a light on a novel molecular mechanism in LUAD progression.
Export adjustment to input trade liberalization: The role of import wholesaling services
Authors: Imbruno Michele
Published: October 2021

This paper studies how input trade liberalization affects export performance, by stressing the important role played by import wholesaling services. Using data from China, we find that input tariff cuts imply a decline in aggregate export revenues in mostly direct‐importing sectors, through the exit of varieties from the export market (extensive margin), and a decrease in the foreign sales of surviving varieties (intensive margin). These effects are due to within‐variety efficiency losses, associated with efficiency gains from market share reallocations across varieties. Opposite results are found in sectors that generally rely on wholesalers when importing intermediate inputs.
Stayers or leavers? Spatial (im)mobility patterns of young university graduates living in rural areas in Poland
Authors: Matysiak Ilona
Published: October 2021

This article aims to explore the (im)mobility patterns of 92 young university graduates living in 10 selected rural municipalities in Poland interviewed within a qualitative study. This is achieved by dividing them into stayers, returnees and newcomers, and looking at their motivations to live in the countryside, plans about their future places of residence as well as their integration into rural communities where they live by analysing their local socializing practices and community engagement. The results show that in each group, those who plan to stay put outnumber the potential leavers—that is, those who would prefer to live elsewhere. The main motivations to stay include a community and family attachment, as well as an aversion to the city or a lack of interest in an urban lifestyle. Having children, property and a social life in the village also contribute to staying. The findings indicate, however, that a university education may affect the interviewees’ integration into the community in terms of weakening their relationships with peers without a university degree and shaping their aspirations and preferences, which do not always match those dominating a rural community.
Recognition of the HLA‐B*51:185 allele in a Taiwanese individual
Authors: Yang Kuo‐Liang , Li Chi‐Cheng , Lin Py‐Yu
Published: October 2021

One nucleotide substitution in codon 77 of HLA‐B*51:01:01:01 results in a novel allele, HLA‐B*51:185.
Training junior doctors to lead rapid responses
Authors: Cetrone Emily , Rozansky Hallie , Ramani Subha
Published: October 2021

Background

Transitions during medical training are a significant source of stress, and junior doctors (residents) primarily learn new skills through on‐the‐job training. As residents transition from postgraduate year (PGY) 1 to 2, they take on new responsibilities, including the management of clinically unstable patients in rapid response (RR) scenarios.

Approach

In 2018, the internal medicine training programme at Brigham and Women's Hospital implemented a ‘Transitions Retreat’ to prepare PGY‐1s for Year 2. In an informal survey, residents endorsed feeling underprepared to lead RRs. We designed a simulation‐based curriculum to teach these skills. Participants completed a questionnaire pre‐simulation and post‐simulation exploring their perceived preparedness. Volunteer residents assessed performance on the simulation using skills checklists and led structured debriefing sessions. We audiotaped, transcribed and thematically analysed these sessions.

Evaluation

Forty‐eight of 58 (82%) PGY‐1s participated. Pre‐intervention, 12.5% felt ‘well‐prepared’ or ‘very well‐prepared’ to lead RRs, compared with 33% post‐intervention. Through qualitative analysis, we identified four key themes in our post‐simulation debriefing conversations: (1) the chaos of RRs, (2) emotional reactions during RRs, (3) challenges and goals of task management and (4) value of interdisciplinary collaboration.

Implications

Though the majority of residents indicated that the curriculum enabled their preparedness to lead RRs and allowed them to process complex emotions in a safe space, we do not know how well this experience translates to the clinical setting. Therefore, we aim to collect follow‐up data 6 months into the PGY‐2 to explore residents' reflections on real‐life experiences as well as whether the simulation impacted their preparedness to lead real‐life RRs.
Impact of immunosuppression on the immune response to SARS‐CoV‐2 infection: A mechanistic study
Authors: Hall Victoria G. , Ferreira Victor , Kumar Deepali , Humar Atul
Published: October 2021

The optimal management of immunosuppression in transplant patients infected with COVID‐19 is unknown. We performed an in vitro study to determine the effect of individual immunosuppressive agents on SARS‐CoV‐2‐specific T‐cell cytokine expression. Convalescent peripheral blood mononuclear cells from eleven non‐immunosuppressed patients with COVID‐19 were preincubated with clinically relevant concentrations of immunosuppressive drugs (tacrolimus, mycophenolate, sirolimus, prednisone) and then stimulated with a SARS‐CoV‐2 peptide pool. Supernatants were analyzed by 14‐plex high sensitivity T‐cell cytokine array. With increasing concentrations of tacrolimus, there was a trend to reduction in the release of IL‐2 (p = .0137), and IFN‐γ (p = .0147) in response to peptide stimulation. There was also a subsequent trend toward a Th2 phenotype, indicated by lower IFN‐γ:IL‐13 ratio (p = .0663) and IFNγ:IL‐4 ratio (p = .0176). Sirolimus appeared to be associated with a proinflammatory cytokine release, including TNF‐α (p = .0027) and IL‐1β (p = .0016), in response to SARS‐CoV‐2 peptides. In contrast, mycophenolate and prednisone did not influence the SARS‐CoV‐2‐specific cytokine response. These are preliminary findings only, with larger studies required to inform clinical recommendations.
An analysis of the trade policy review of the European Union
Authors: Jackson Karen
Published: October 2021

This paper provides an analysis of the latest World Trade Organisation Trade Policy Review of the European Union. The review period was one of heightened trade tensions, where the dynamic between China–US–EU dominated the policy agenda. A number of key findings emerge from the review, broader literature and events after the review period: (i) much remains to be negotiated as part of Brexit, (ii) there has been a change of approach whereby trade and investment agreements tend to be separate; this has important implications for the speed of implementation, (iii) strategic oversight regarding extra‐EU investment inflows hinges on national screening mechanisms, (iv) rival infrastructure development schemes are emerging, suggesting that the EU will struggle to create space for their own initiative, (v) free trade agreements are increasingly covering a broader range of issues such as labour rights and environmental protection and (vi) digitisation and a tax schedule for digital services is still work in progress. Overall, the review is an extremely useful reference document. However, a critical assessment of the factual information is necessary.
Embedding spheres in knot traces
Authors: Feller Peter , Miller Allison N. , Nagel Matthias , Orson Patrick , Powell Mark , Ray Arunima
Published: October 2021

The trace of the$n$-framed surgery on a knot in$S^{3}$is a 4-manifold homotopy equivalent to the 2-sphere. We characterise when a generator of the second homotopy group of such a manifold can be realised by a locally flat embedded$2$-sphere whose complement has abelian fundamental group. Our characterisation is in terms of classical and computable$3$-dimensional knot invariants. For each$n$, this provides conditions that imply a knot is topologically$n$-shake slice, directly analogous to the result of Freedman and Quinn that a knot with trivial Alexander polynomial is topologically slice.
Fabrication of Robust Superhydrophobic Nickel Films on Steel Surface With High Corrosion Resistance, Mechanical and Chemical Stability
Authors: Abd-El-Nabey B. A. , Ashour M. , Aly A. M. , Mohamed M. E.
Published: October 2021

Superhydrophobic films were successfully grafted on a steel substrate using potentiostatic electrodeposition of nickel followed by treatment with myristic acid (MA) as a low surface energy material. A scanning electron microscope (SEM) was used to investigate the surface topography of the prepared superhydrophobic films. The results revealed that the prepared Ni films modified by myristic acid have micro-nano structures. Fourier transform infrared spectrophotometer (FTIR) and X-ray diffraction (XRD) measurements showed that the steel substrate was coated with nickel film modified with myristic acid. Three different nickel films were prepared: the Ni-MA (I) deposited from pure nickel sulfate bath (1.0 M NiSO4), Ni-MA (II) deposited from pure nickel chloride bath (1.0 M NiCl2. 6H2O), and the third Ni-MA (III) film deposited from Watts bath (0.2 M NiCl2. 6H2O and 0.8M NiSO4). The superhydrophobic Ni-MA (I) film has the highest corrosion resistance, chemical stability, and mechanical abrasion resistance, while Ni-MA (II) film has the lowest properties.
Design, Analysis, and Fabrication of Water Turbine for Slow-Moving Water
Authors: Adnan Muaz , Tahir Muhammad Ausaf , Jamal Muhammad Azfar , Aslam Zeshan , Irfan Talha , Umer Muhammad
Published: October 2021

The energy crisis of the modern era may be overcome by hydrokinetic energy, the most readily and free source of energy available, to provide basic electricity needs to remote and urban areas at a low cost. The kinetic energy of flowing water at low speed could be extracted effectively by designing an appropriate design of the blade, as the turbine’s performance is dependent upon the shape of its blade. In this study, the wind turbine model with some modifications was used to design a blade for the hydrokinetic turbine. The horizontal axis turbine model with propeller type configuration was selected for obtaining higher efficiency. The optimum hydrofoil was selected and designed with an optimal twist angle for the maximum energy extraction process. The model was designed in three-dimensional (3D) modeling software solidworks, and then the power analysis was carried out through numerical simulations using the commercial computational fluid dynamics package ansys fluent. The power output was analyzed with a different number of blades, and performance curves were generated for the most efficient system. The calculations exhibited that for 1.5 m/s rated speed of water with the rotor diameter of 0.6096 m provides the rated power of approximately 150 W at 110 RPMs. The power curve of the turbine was analyzed for the selection of an efficient Permanent Magnet Synchronous Generator, and a direct drive system was preferred to reduce the weight and losses. The turbine model was 3D printed for testing and experimentation. The analytical efficiency calculated was 30.52%, and the experimental efficiency achieved was 28.24%. This study shows that the optimum design of hydrokinetic turbines could be integrated into series to provide energy to remote areas where the construction of dams and other resources are not available.
PEGASOS - A New Linking Mechanism for Modular Osteosynthesis Plates in Minimally Invasive Acetabular Surgery
Authors: Trulson Alexander , Küper Markus A. , Leis Artur , Stöckle Ulrich , Stuby Fabian , Hossfeld Max
Published: October 2021

Background: Recently presented minimally invasive endoscopic surgical techniques demonstrated the feasibility of implanting standard osteosynthesis plates for pelvic fractures. The reconstruction and internal fixation of complex acetabular fractures is still challenging. The goal of this study is to introduce a divisible implant, with a positive-locking in situ linking mechanism for plate osteosynthesis, making it possible to stabilize large and complex acetabular fractures with involvement of the quadrilateral surface.

Method: Standard implants were used to recreate a base design. Using computer aided design (CAD), a three-dimensional standard implant was divided into two parts, so they could be re-allocated in situ. A critical objective was to reduce the cross-section of each part (clearance gauge). To connect the separated parts in situ, a new linking mechanism (cone in cone) was created. The new construct also features self-stabilization, self-centering, reinforced positional movement and preloading effects.

Results: A linking system for plate osteosynthesis was developed entitled PEGASOS ("Percutaneous Endoscopic Guided Acetabulum-Stabilizing Osteosynthesis System"). Endoscopic implantation and in-situ-linking could be performed in a human cadaver. Therefore, we could demonstrate, that buttressing the quadrilateral surface of the acetabulum could be performed minimally invasive using a divisible suprapectineal buttress plate.

Conclusion: We created a linking mechanism to couple two plates in situ. This mechanism enables an extremely strong, positive-locking connection, whereas its geometric shape allows for different relative movements during the locking procedure, with a single screw.
Measurement and Analysis of Power Losses in Sintered Cores for Power Electronic Devices in Renewable Energy Systems
Authors: Lasek Pawel , Stepien Mariusz
Published: October 2021

Measurement of power losses in inductive devices in highly efficient power electronic systems is crucial for choosing appropriate components. A calorimetric method for measuring power losses below 10 W is presented in the following paper to decompose the inductive devices’ power losses. A fully enclosed double-jacked calorimetric chamber is constructed to measure the temperature with digital temperature sensors TMP275, providing a resolution of 0.1 W/K. The finite element method is used with analytical calculation to estimate core and conduction losses to decompose power losses. Power losses are measured for an inductor with a 3C95 ferrite core and four types of windings, where three were made of wire with a different number of strands, whereas the fourth has been made using copper foil. All windings have similar cross-sectional areas for comparison.
Research of a Fast Sample Preparation Method for Water Radioactivity Measurement
Authors: He Shuijun , Wang Xiangwei , Liang Manchun , Su Guofeng , Chen Anying , Zhang Chao , Li Ke
Published: October 2021

Radionuclide activity concentration in drinking water cannot be measured directly at normal conditions. The water samples need to be concentrated under mild boiling conditions according to relevant standards. However, the method takes too long a time that it can hardly handle emergency measurements. A fast concentration method based on vacuum and low temperature is proposed in this study. The method was validated in the gross alpha and gross beta measurement of drinking water samples. The sample preparation time based on liquid scintillation counting (LSC) is only about 80 minutes, and the recovery percent of alpha certified sample is more than 80%, and that of beta certified sample is more than 90%. The experimental results show that the method can be used not only for the preparation of samples of gross alpha and gross beta measurement, but also for the preconcentration of specific nuclides measurement.
Experimental Study on Aerosol Transport Behavior in Multiple Cells With Expandable Connecting Pipe for Safety Assessment of Sodium-Cooled Fast Reactors
Authors: Umeda Ryota , Kondo Toshiki , Kikuchi Shin , Kurihara Akikazu
Published: October 2021

Sodium fire is one of the accidental events in case of sodium leak of sodium-cooled fast reactor. This event is basically the reaction between liquid sodium and oxygen with exothermic heat. The transport behavior of the aerosol as reaction product (sodium oxide) by sodium fire through the air duct between cells may cause damage and failure of the control devices and harmful effect against human body. Previously, many experimental works on sodium fire have been carried out in single cell. However, the finding on the sodium fire experiments using multiple cells is quite limited. Thus, the elucidation of aerosol transport phenomenon between cells is indispensable for validation of sodium fire analysis code.

In this study, in order to obtain the fundamental information on aerosol transport behavior between cells, the development of Multiple cells with Expandable connecting pipe Test (hereinafter referred to as “MET”) facility and related experimental devices have been carried out since 2016. The MET facility comprises 3 cells and several expandable connecting pipes and has the flexible cells arrangement capability for desired multiple cells layout. Also, the size of the cell was determined on the basis of Grashof number to simulate the condition of natural convection heat transfer in case of sodium fire. Each cell comprises 6 wall panels made of both acryl and matte black coating aluminum. For simulant of sodium fire aerosol, silica particle (approximately 2.2 g/cm3, 1μm) was used to simulate the density of sodium oxide produced by sodium fire and primary particle size of the aerosol based on the results obtained by in-situ measurement using laser diagnostics for sodium-oxygen counter flow in our previous work.

The preliminary experiments using 2 cells connected with horizontal or vertical pipe were performed to observe the particle diffusion and transport behavior. The stable particle supply was confirmed in the particle supply cell, and the basic feature on transport behavior between 2 cells was observed by using video camera. After experiment, the particle settled in the floor of each cell was collected and weighed. As a result, certain amount of particle sedimentation was detected in the adjacent cell, which is evident from observation of the particle diffusion and transport behavior. Thus, the basic feature on transport behavior and sedimentation of the particles in the MET facility were confirmed.
Experimental Study on Heat Transfer Characteristics of Water Injection on Molten Pool With Low Mass Fraction of Zirconium
Authors: Li Zongyang , Chang Huajian , Fang Fangfang , Han Kun , Hao Botao , Chen Lian
Published: October 2021

In-Vessel Retention (IVR) strategy with water injection on the molten pool can ensure the nuclear safety and reduce the possibility of vessel failure. The wATer injectiOn on molten Zirconium-Stainless steel Metallic pool experiment (ATOM) has been performed to investigate the effect of water injection on the heat transfer of the molten pool. The simulant of the molten pool contains the low mass fraction of Zirconium (13%). Two water injections are carried out with the same mass flow. When water is injected on the melt surface, the heat flux transferred to water of the first and the second water injection are about 1.3 MW/m2 and 1.7 MW/m2, respectively. The heat flux in ATOM test is larger than that of the calculated result of Berenson film boiling correlation by 5.3 times for the first water injection and 8.0 times for the second water injection. When water is injected, the melt temperature could be cooled effectively and the heat flux to the sidewall is reduced too. The results indicated that water injection on the surface of the light metallic layer could effectively cool the molten pool and reduce the thermal focusing on the RPV. Neither vapor explosion nor melt ejection is found for the low mass fraction of the Zirconium test.
Steady-State Performance Analysis of a Dual-Cladding Design for Accident Tolerance Fuel
Authors: Deng Qianliang , Li Songyang , Wang Dingqu , Jiang Yueyuan , Liu Zhihong , Xiong Wei , Tian Yalin
Published: October 2021

The 2011 Fukushima Daiichi accident has highlighted the fatal weaknesses of the currently using fuel system, global interest has expanded in exploring an alternative accident-tolerance fuel (ATF) with enhanced performance during not only accident conditions but also normal operation. Therefore, this paper proposed a novel Dual-Cladding design concept to decrease the probability of cladding failure and increase the accident-tolerance ability of fuel rods in 200MW Nuclear Heating Reactor II (NHR200-II). Compared to the single cladding of conventional PWR fuel, the Dual-Cladding rod has bilayer zirconium-based alloy cladding, which means that an extra zircalloy cladding is added outside the inner zircalloy cladding and the total diameter of the rod is unchanged. This concept can directly decrease the probability of cladding failure to 10% of typical value under normal operation according to relevant probabilistic risk assessment theory and increase fuel coping time during accident conditions in NHR200-II. On the other hand, enrichment of the pellet will be adjusted in this design. And there are also some challenges needed to be addressed, such as heat transfer between the two layers of cladding and fabrication of the rod. This paper showed the basic design of the Dual-Cladding fuel rod and analyzed thermal behavior under normal operation. This concept provides a fresh and economical way to improve the accident-tolerance ability of currently using fuel in NHR200-II.
Study on the Applicability of Typical Valve Failure Data to Non-Reactor Nuclear Fuel Cycle Front-End Facilities
Authors: Lyu Dan , Yang Xiao-wei , Lu Yan , Wang Shi-jun , Xu Chun-yan
Published: October 2021

Probabilistic safety analysis (PSA) has played an important role in the safety analysis in the field of nuclear power plant, and it could be the development direction of future safety analysis in the field of non-reactor nuclear fuel cycle front-end facilities. In order to promote the PSA in the field of non-reactor nuclear fuel cycle front-end facilities in China, it is necessary to carry out study on the failure frequency of some common equipment used in the non-reactor nuclear fuel cycle front-end facilities. The valve is a kind of quite common equipment used in the non-reactor nuclear fuel cycle front-end facilities to control the transport of various kinds of materials. Based on the failure frequency of the valve collected and calculated in the field of nuclear power plants in the United States of America, the field of the chemical industry in the United States of America and the field of nuclear power plants in China as well, comparison and assessment of the failure modes and failure frequencies of different types of the valve were carried out, and suggestions for the assignment of the failure frequency of the valve in the field of non-reactor nuclear fuel cycle front-end facilities in China were proposed. The study results show that, the failure frequency of the valve in the field of nuclear power plants in the United States of America, the field of the chemical industry in the United States of America and the field of nuclear power plants in China has a high consistency, and the data of the failure frequency of the valve in these three fields could be used as reference for the PSA work in the field of non-reactor nuclear fuel cycle front-end facilities in China; besides, it is necessary to start the raw data sampling and statistical work for the failure frequency calculation of the valve as early as possible in Chinese non-reactor nuclear fuel cycle front-end facilities, so as to obtain the failure frequency and confidence interval of the valve which is suitable for Chinese nuclear chemical engineering practice.
Research on Tritium Behavior Issues in High-Temperature Gas-Cooled Reactors
Authors: Zhou Ziling , Li Chuan , Gui Nan , Xie Feng , Wen Yanwei , Shan Bin , Fu Jia , Fan Qunchao
Published: October 2021

The very-high-temperature reactor (VHTR) has been included in the conception of the Generation IV nuclear energy system proposed by the United States Department of Energy Nuclear Energy Research Advisory Committee and the Generation IV International Forum. After the Fukushima accident, concern has grown regarding the safety of nuclear power plants. For its inherent safety, superior proliferation resistance, and high thermal efficiency, the VHTR and its prototype, the high-temperature gas-cooled reactor (HTGR), attracted worldwide interest. Tritium exists in the fuel element and graphite reflectors in the core, primary coolant, some liquid and solid wastes, and gaseous effluent of HTGRs. Due to its permeation behavior at high temperatures, tritium is the most important nuclide in the secondary loop of HTGRs. Considering the future application of HTGRs in hydrogen production, tritium will be non-negligible and could be difficult to separate from hydrogen. In addition, the interaction between tritium and graphite is expected to be very strong. The absorption, desorption, and diffusion of tritium at the interface between the primary coolant and graphite are of great interest. Experimental measurements of the diffusion coefficients of tritium and its isotopes do not agree well with theoretical predictions based on the consideration of isotope effects. In this paper, research progress on the permeation, absorption, desorption, and diffusion behaviors of tritium in HTGRs is summarized and discussed. The chemical form of tritium in the primary coolant, and its spectroscopic characteristics, internal structures, and transport behaviors are organized and analyzed. Basic properties related to tritium, such as isotope effect, nuclear spin, radioactivity, etc. are also discussed.
Thermal Hydraulics Analysis of a High-Performance Once-Through Steam Generator With Annular Narrow Slot Tube
Authors: Han Jinyu , He Wen , Guan Shunran , Zhao Chenru , Bo Hanliang
Published: October 2021

The integrated small modular reactors (SMR) have been attracting more and more attentions in the field of nuclear energy. For PWR-type SMR with full-power natural circulation, a built-in steam generator with high heat transfer performance is required to enhance the natural circulation capability of the core. The heat exchanger with annular narrow slot tube takes the advantages of heat transfer enhancement of narrow slot and double-sides heat exchange in both internal and external sides, and results in higher heat transfer efficiency compared with the conventional heat exchanger with straight tube. Therefore, it is regarded as a promising design scheme of built-in steam generator with great potential. However, there have been relatively few researches on the design and calculation of steam generator with narrow slot tube. On the other hand, the flow boiling heat transfer in micro/mini channels (generally with hydraulic diameter less than 3 mm) is more complicated than that in a regular flow channel. Heat transfer correlations developed especially for micro/mini-channels with high accuracy are required for accurate predictions.

In the present paper, thermal-hydraulic design calculations and analysis for the once-through steam generator (OTSG) with annular narrow slot tube. The thermal-hydraulic performance was quantitatively evaluated and compared with that of the conventional OTSG with straight tube, such as the OTSG designed by B&W, based on the heat transfer coefficient, heat exchange area, area density, power density, steam generator volume power and other parameters.

Finally, the working performance of the steam generator and the coupled heat transfer characteristics with the primary loop of natural circulation under steady-state operating conditions were studied, and the feasibility and applicability of the OTSG with annular narrow slot tube used in a full-power natural circulation integrated SMR were discussed.
Research on the Diagnosis Model of Break Diameter During the Blowdown Process of SBLOCA
Authors: Ke Bingzheng , Gao Puzhen , Cheng Kun , Wu Lingyan , Wang Bo , Chen Bowen , Tian Ruifeng , Wen Jiming
Published: October 2021

The small break loss of coolant accident (SBLOCA) is a typical accident in the nuclear power plant, and the diagnosis of accident parameters in a small break loss of coolant accident (SBLOCA) is a very important research direction in the field of nuclear safety. The timely and accurate judgment of the break parameters can help the operator understand the serious situation of the SBLOCA and avoid more serious consequences. In this study, a physical model of the blowdown process during SBLOCA was established by using the theory of two-phase critical flow, flash evaporation, and energy conversion. Then a diagnostic model for the break diameter of SBLOCA was established by combining the NSGA-II and the physical model, and the experimental results obtained by the blowdown experiment of simulated pressurizer under a low pressure condition were used to verify the accuracy of results obtained by the diagnostic model. The results show that the diagnosis model can be used to obtain the break diameter during the blowdown process of SBLOCA. In different conditions of the blowdown process, the errors between the diagnosis results and the experiment results do not exceed 20%. The calculation time of the diagnostic model is less than 400s.
Numerical Analysis on the Thermal-Hydraulic Characteristics for the Reactor Main Vessel Cooling System of Chinese Sodium Cooled Fast Reactor
Authors: Song Ping , Feng Tangtao , Zhang Dalin , Chen Lie , Li Shaodan , Lin Yuansheng , Qiu Suizheng
Published: October 2021

As a critical component for pool-type Sodium cooled Fast Reactor (SFR), the main vessel plays a major role in holding the entire sodium in the pool. While the Reactor Vessel Cooling System (RVCS) would contribute to the cooling of the main vessel. This paper develops a one-dimensional code and the numerical analysis has been conducted to evaluate the thermal-hydraulic characteristics for RVCS for China Experimental sodium-cooled Fast Reactor (CEFR). Firstly, the code is applied to the analysis on the steady characteristics of RVCS and the results are compared with the design value. The simulation results show that the main vessel is cooled effectively and the comparison results are in good agreement with the design value. Then, in order to study the transient characteristics of RVCS, the code is coupled with the Transient Thermal-Hydraulic Analysis Code for Sodium-cooled fast reactors (THACS). The simulation finds that a reverse flow in RVCS shows up and RVCS could take the decay heat out effectively, which contributes a lot to the core cooling. The code evaluated the thermal-hydraulic characteristics as well as the decay heat removal capacity of RVCS. The results are very promising but further experimental data is still needed to validate the code.
Corrosion Behavior of Superalloys in High Temperature Gas Cooled Reactor in Impure Helium With Corrosion Time
Authors: Li Haoxiang , Du Bin , Zheng Wei , Wang Qiuhao , Yin Huaqiang , He Xuedong , Fan Hua , Ma Tao
Published: October 2021

There are trace impurities such as CO, CH4, H2, H2O in helium of main cooling loop of high temperature gas cooled reactor, which will cause corrosion of superalloy materials used in steam generator and intermediate heat exchanger at high temperature. Previous experiments and literatures show that the formation of chromium rich protective oxide layer on the surface of superalloy is an important factor to prevent severe corrosion of superalloy. In this paper, the corrosion tests of four candidate materials Inconel 617, Incoloy 800H, Hastelloy X and T-22 for high temperature reactor steam generator were carried out. The four superalloys were exposed at 950 °C for 50, 100, 150 and 200 hours in helium with a certain impurity content. The corrosion results were analyzed by weighing, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The corrosion of these four alloys occurred in different degrees. In this paper, we mainly analyse the conclusion of 50h and 200h corrosion of these four kinds of superalloys. On the whole, Hastelloy X and T-22 have good corrosion resistance and low mass gain; Inconel 617 and Incoloy 800H have poor corrosion resistance, obvious internal oxidation and high mass gain.
Research on Electric and I&C Equipment Safety Function Classification of Nuclear Power Plant
Authors: Yuqi Wang , Qian Sun
Published: October 2021

Classification of System, Component and Structure (SSC) is the base as well as high level demand of nuclear power plant. Equipment classification including electric and Instrument and Control (I&C) equipment is the precondition of correct design regulation and standard. Safety function classification is key pass of electric and I&C equipment classification. This paper researches the method of nuclear power plant electric and I&C equipment safety function classification. Firstly from view of function, it explains the importance of function classification. Then function analysis and classification of equipment is implemented by design order. Lastly from view of accident analysis, function classification is validated, and a complete approach of function classification is formed. The purpose of this paper is the NPP electric and I&C equipment safety function classification as an example, to study and summarize the method of the electric and I&C equipment safety function classification, and to provide the basis for specific items design work according to design requirements. At the same time, a practical method is provided for other similar NPP electric and I&C equipment classification work. The electric and I&C equipment function classification of nuclear power plant satisfy the basic principles requirement of relative nuclear power rules and codes. It provides an important basis of equipment classification for next nuclear power plants.
Flux Rate Calculation and Analysis of the Integrated Small Pressurized Water Reactor Based on Monte Carlo Method
Authors: Yang Wen , Chao Fei , Tai Yun , Li Longze
Published: October 2021

The neutron and photon flux rates are important parameters for safe reactor operation, refueling and decommissioning, scientific applications and radiation protection. For the Integrated small pressurized water reactor, the advanced reactor core analysis code CORAL, the source calculation code ORIGEN-II and the Monte Carlo code SuperMC are used to establish the reactor flux rate calculation model under normal operation and shutdown refueling condition. The results show that (1) In the normal operation of the reactor, the neutron flux rate is attenuated by 10 orders of magnitude from the outermost component to the inner surface of the pressure vessel, and the shielding effect of the coolant on neutrons is more significant. The neutron flux of the inner surface of the pressure vessel in 40 years is 3.723 × 1014 ncm2; the neutron flux in 60 years is 5.585 × 1014 ncm2. The photon flux rate is reduced by 10 orders of magnitude from the periphery of the core to the outer surface of the pressure vessel. High-quality density materials have better photon shielding effects. (2) In the case of reactor shutdown and refueling, the neutron flux rate is much smaller than the photon flux rate. On the outer surface of the pressure vessel, the maximum neutron and photon dose rates are 7.74 × 10−10 mSv · h−1 and 6.97 × 10−5 mSv · h−1, respectively, which belong to the supervision area. When the cover is opened, the radiation dose value of the workplace at the top of the reactor is less than 0.0025 mSv · h−1, which can ensure the radiation safety of the operation.
Linear Active Disturbance Rejection Control of Steam Bypass System for a Pressurized Water Reactor
Authors: Zhang Xianshan , Sun Peiwei , Wei Xinyu , Gou Xiaolong , Tan Guocheng , Tian Yajie
Published: October 2021

China has recently promised to reach carbon neutral before 2060. To achieve this ambitious goal, it is necessary to substantially increase the electricity production from clean sources, such as renewable power and nuclear power, to replace the previous share of coal power generation. Most of the nuclear reactors currently in operation in China are pressurized water reactors (PWR). The nuclear steam supply system (NSSS) in PWR is a complex nonlinear system. The steam bypass system ensures the steam generator’s cooling capacity in accident conditions and is essential for safe and efficient plant operation. Because of the broad transport delay and non-linearity in the steam bypass control system, it is difficult for the currently widely used proportional-integral-derivative (PID) control to obtain satisfactory control effects. Therefore, it is necessary and meaningful to design a suitable steam bypass control system for NSSS.

The investigation of the steam bypass system is performed by MATLAB & Simulink for a large-scale PWR. The nonlinear model is developed by applying the mass and energy conservation equations of fluids and the critical flow correction. The state-space multivariable models are derived by linearizing the nonlinear model at different operation points. Open-loop simulation experiments have been carried out to study the steam bypass system’s dynamic, and the state-space model simulation results are validated by comparing with the results from the nonlinear model. The open-loop results show that the overall system has a considerable transport delay. Thus, a linear active disturbance rejection controller (LADRC) is designed for the steam bypass system. This research assumes that the model and the amount of delay are nearly unknown; however, the proposed controller still performs better than the existing Ziegler-Nichols (Z-N) tuned PID controller. The LADRC has a shorter settling time than the PID controller; the control system can satisfy the design purposes.
Study on the Dynamic Modeling of the Micro-High Temperature Gas Cooled Reactor for Control System Design
Authors: Qiu Leilei , Wei Xinyu , Sun Peiwei , Liao Shengyong
Published: October 2021

The micro-high temperature gas cooled reactor (Mi-HTR) uses Tri-structural iso-tropic (TRISO) particle as fuel, helium gas as coolant, and graphite as moderator and structural material. The reactor adopts complete passive residual heat removal technology and is inherent security. The usage of the Mi-HTR is megawatt-level micro nuclear power plant. Because of the using of hexagonal prism graphite core, the dynamic characteristics of the Mi-HTR are different from large scale high temperature gas cooled reactors and pressurized water reactors. Therefore, the accurate and reliable reactor dynamic characteristics analysis are of significance for the design of the Mi-HTR control system. The neutron kinetics model of the Mi-HTR is built based on the point reactor kinetics with the reactivity feedback mechanism. The core thermal-hydraulic model of the Mi-HTR is built based on the fundamental conservation laws. By coupling the two models, a lumped-parameter model of the Mi-HTR is established. In order to obtain an accurate transfer function model for subsequent control system design, the mechanism model is linearized based on perturbation theory, and then the transfer function model with different inputs and outputs is obtained through Laplace transform.

The developed nonlinear model is implemented on MATLAB/Simulink. By introducing a variety of disturbances, the simulation results of transient responses are presented, which show that the static precision of the dynamic model is satisfactory, and the trend of the transient responses is consistent with the physical laws. The obtained transfer function model and the nonlinear model are introduced with the same disturbances, and the simulation results show that the responses of transfer functions are consistent with those of the nonlinear model. Therefore, the transfer function model can be utilized to control system design for the Mi-HTR.
Preliminary Evaluation on the Relocation Phase of Ex-Vessel Debris of Fukushima Daiichi Nuclear Power Plant Unit-3
Authors: Li Xin , Yamaji Akifumi , Furuya Masahiro , Sato Ikken , Madokoro Hiroshi , Ohishi Yuji
Published: October 2021

To deepen our understanding for the current debris status and investigate the debris-structure interactions in the pedestal region of Fukushima Unit-3, the Moving Particle Semi-implicit (MPS) method is further developed for simulation of multi-component liquid/solid relocation with solid-liquid phase changes aiming for plant-scale practices. The improvement of the existing MPS method mainly consists of two parts, namely 1) the improvement of numerical stability and accuracy, including a) applying second-order corrective matrix to the particle interaction models and b) particle shifting that can optimize particle configurations; and 2) improvement of calculation efficiency, including a) hybrid OpenMP and MPI parallelization and b) particle type-dependent speed-up algorithms to reduce calculation costs for particles with extremely high viscosity and low velocity.

In the current study, the improved MPS method is validated against the experiments carried out at Waseda University, in which molten salt droplets were released to interact with aluminum pillars and solidify on them. Good agreement of the total height of the solidified salt and its distribution on the pillars has been achieved. The successful validation has shown the capability of the current MPS method for simulations of Unit-3 pedestal region.
Configuration Risk Management Support for the Maintenance Rules at Qinshan NPP1
Authors: Wang Li , Wang Zilong , Liu Deyi , Xu Jie , Zhou Jianzhang , Zou Shengjia
Published: October 2021

This article first briefly introduces the “Technical Policy for Improving the Maintenance Effectiveness of Nuclear Power Plants (Trial)” issued by the National Nuclear Safety Administration (NNSA) in August 2017 and the implementation background of the Maintenance Regulations (MR) of the First Plant of Qinshan. Based on the general introduction of the implementation process of MR, the important roles played by the configuration risk management during the implementation of the MR project of Qinshan NPP1 are detailed: 1) The background of configuration risk management and December 30, 2019 “Technical Policy for Nuclear Power Plant Configuration Risk Management (Trial)” issued by the National Nuclear Safety Administration (NNSA); 2) describes the relationship between configuration risk management and maintenance rules and how to apply configuration risk management to implement maintenance rules The scope of activities to carry out configuration risk management and the requirements for the risk threshold of maintenance activities; 3) the method of risk assessment and the establishment of a risk management action matrix on the basis of the EPRI document; 4) the introduction of probabilistic safety assessment (PSA) in the role of configuration risk management; 5) The actual case of configuration risk management is used to show how to configure risk management to solve the requirements of risk assessment in maintenance rules before maintenance activities. As the first operating nuclear power plant in China to formally carry out MR work, the application of Qinshan NPP1 in the implementation of MR configuration risk management can provide a good experience for other domestic nuclear power plants.