This paper discusses the results obtained during an investigation of WWER-1000 Nuclear Power Plant (NPP) behavior at shutdown reactor during maintenance. For the purpose of the analysis is selected a plant operating s...This paper discusses the results obtained during an investigation of WWER-1000 Nuclear Power Plant (NPP) behavior at shutdown reactor during maintenance. For the purpose of the analysis is selected a plant operating state with unsealed primary circuit by removing the MCP head. The reference nuclear power plant is Unit 6 at Kozloduy NPP (KNPP) site. RELAP5/ MOD3.2 computer code has been used to simulate the transient for WWER-1000/V320 NPP model. A model of WWER-1000 based on Unit 6 of KNPP has been developed for the RELAP5/MOD3.2 code at the Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS), Sofia. The plant modifications performed in frame of modernization program have been taken into account for the investigated conditions for the unsealed primary circuit. The most specific in this analysis compared to the analyses of NPP accidents at full power is the unavailability of some important safety systems. For the purpose of the present investigation two scenarios have been studied, involving a different number of safety systems with and without operator actions. The selected initiating event and scenarios are used in support of analytical validation of Emergency Operating Procedures (EOP) at low power and they are based on the suggestions of leading KNPP experts and are important in support of analytical validation of EOP at low power.展开更多
A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accu...A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accurately,we establish corresponding equivalent mathematical model considering magnetic leakage based on magnetic circuit and circuit dualistic transformation method.The distribution of magnetic leakage field of each winding is analyzed qualitatively,and the analytical calculation formulas of magnetizing inductance and leakage inductance of each winding are derived.Based on this,the analytical calculation formulas of short-circuit impedance and winding current of CRT under different working conditions are derived.The field-circuit coupling finite element model of the magnetic integrated CRT is established to simulate the current of each winding under different working conditions.The results show that the analytical calculation results of each winding current have good consistency with the finite element calculation results,indicating the validity of CRT equivalent mathematical model and correctness of the analytical formulas of leakage inductance,short-circuit impedance and winding current of CRT.The working winding current of CRT is increasing gradually with the operation of control winding in turn to realise the transition of CRT compensation capacity from zero to a rated value.展开更多
With rapid development of nuclear power in China, in view of reactor type selection, this paper analyzes the current situation that faces nuclear power industry, the technical characteristics of optional reactors and ...With rapid development of nuclear power in China, in view of reactor type selection, this paper analyzes the current situation that faces nuclear power industry, the technical characteristics of optional reactors and the tendency of nuclear power technology development in the future. The proposals put forward in this paper include choosing and introducing GW-class advanced PWR as main reactors, carrying out self-supporting projects and technical transfer negotiations, in addition, promoting the design of the advanced generation-Ⅱ PWR and initiating small-scaled construction. The ultimate target is to catch up with the world advanced level by means of technical upgrading and recreation based on technology importation and assimilation.展开更多
Torrefaction is mild thermochemical pretreatment technology that enhances biomass by changing its physico-chemical characteristics to produce a high-quality solid biofuel.The present study evaluated the performance of...Torrefaction is mild thermochemical pretreatment technology that enhances biomass by changing its physico-chemical characteristics to produce a high-quality solid biofuel.The present study evaluated the performance of a continuous screw-auger-type torrefaction system for upgrading agricultural residues rice husk(RH)and wheat straw(WS)into energy-dense,hydrophobic biomass suitable for cofiring applications.Torrefaction experiments were conducted at three temperatures of 250℃,275℃,and 300℃ with a total residence time of 12 minutes.The results revealed that the mass yield decreased with temperature,from 85.60%to 75.00%and from 83.20%to 70.80%for RH and WS,respectively.Higher heating values increased significantly with torrefaction severity,reaching 19.26 MJ/kg for RH and 20.25 MJ/kg for WS when torrefied at 300℃,representing a 22%-25%improvement over raw biomass.Moisture uptake dropped substantially from 38.6%to 1.9%and from 41.5%to 2.1%for RH and WS,respectively,indicating the enhanced hydrophobicity.Combustion indices have also showed desirable trends;the fuel ratio increased to 0.54 and 0.57,and the volatile ignitability exceeded 15 MJ/kg for both biomass samples torrefied at 300℃,indicating improved ignition characteristics suitable for cofiring.Techno-economic analysis revealed a net profit of 138520 Indian rupees/year,with a payback period of 5 years and a benefit-cost ratio of 1.27,supporting the economic feasibility of the system.Overall,the study confirms that torrefied biomass presents improved fuel characteristics and combustion behaviour,making it a viable solution for clean-energy transition and sustainable waste management.展开更多
文摘This paper discusses the results obtained during an investigation of WWER-1000 Nuclear Power Plant (NPP) behavior at shutdown reactor during maintenance. For the purpose of the analysis is selected a plant operating state with unsealed primary circuit by removing the MCP head. The reference nuclear power plant is Unit 6 at Kozloduy NPP (KNPP) site. RELAP5/ MOD3.2 computer code has been used to simulate the transient for WWER-1000/V320 NPP model. A model of WWER-1000 based on Unit 6 of KNPP has been developed for the RELAP5/MOD3.2 code at the Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS), Sofia. The plant modifications performed in frame of modernization program have been taken into account for the investigated conditions for the unsealed primary circuit. The most specific in this analysis compared to the analyses of NPP accidents at full power is the unavailability of some important safety systems. For the purpose of the present investigation two scenarios have been studied, involving a different number of safety systems with and without operator actions. The selected initiating event and scenarios are used in support of analytical validation of Emergency Operating Procedures (EOP) at low power and they are based on the suggestions of leading KNPP experts and are important in support of analytical validation of EOP at low power.
基金Weinan Science and Technology Plan Project(No.2020ZDYF-JCYJ-177)General Special Scientific Research Projects of Education Department of Shaanxi Provincial Government(No.21JK0582)+2 种基金Young and Middle-aged Scientific and Technological Talents Project of Shaanxi Railway Institute(No.KJRC202001)Scientific Research Fund Project of Shaanxi Railway Institute(No.KY2021-34)Science and Technology Innovation Team of Shaanxi Railway Institute(No.KJTD201901)。
文摘A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accurately,we establish corresponding equivalent mathematical model considering magnetic leakage based on magnetic circuit and circuit dualistic transformation method.The distribution of magnetic leakage field of each winding is analyzed qualitatively,and the analytical calculation formulas of magnetizing inductance and leakage inductance of each winding are derived.Based on this,the analytical calculation formulas of short-circuit impedance and winding current of CRT under different working conditions are derived.The field-circuit coupling finite element model of the magnetic integrated CRT is established to simulate the current of each winding under different working conditions.The results show that the analytical calculation results of each winding current have good consistency with the finite element calculation results,indicating the validity of CRT equivalent mathematical model and correctness of the analytical formulas of leakage inductance,short-circuit impedance and winding current of CRT.The working winding current of CRT is increasing gradually with the operation of control winding in turn to realise the transition of CRT compensation capacity from zero to a rated value.
文摘With rapid development of nuclear power in China, in view of reactor type selection, this paper analyzes the current situation that faces nuclear power industry, the technical characteristics of optional reactors and the tendency of nuclear power technology development in the future. The proposals put forward in this paper include choosing and introducing GW-class advanced PWR as main reactors, carrying out self-supporting projects and technical transfer negotiations, in addition, promoting the design of the advanced generation-Ⅱ PWR and initiating small-scaled construction. The ultimate target is to catch up with the world advanced level by means of technical upgrading and recreation based on technology importation and assimilation.
文摘Torrefaction is mild thermochemical pretreatment technology that enhances biomass by changing its physico-chemical characteristics to produce a high-quality solid biofuel.The present study evaluated the performance of a continuous screw-auger-type torrefaction system for upgrading agricultural residues rice husk(RH)and wheat straw(WS)into energy-dense,hydrophobic biomass suitable for cofiring applications.Torrefaction experiments were conducted at three temperatures of 250℃,275℃,and 300℃ with a total residence time of 12 minutes.The results revealed that the mass yield decreased with temperature,from 85.60%to 75.00%and from 83.20%to 70.80%for RH and WS,respectively.Higher heating values increased significantly with torrefaction severity,reaching 19.26 MJ/kg for RH and 20.25 MJ/kg for WS when torrefied at 300℃,representing a 22%-25%improvement over raw biomass.Moisture uptake dropped substantially from 38.6%to 1.9%and from 41.5%to 2.1%for RH and WS,respectively,indicating the enhanced hydrophobicity.Combustion indices have also showed desirable trends;the fuel ratio increased to 0.54 and 0.57,and the volatile ignitability exceeded 15 MJ/kg for both biomass samples torrefied at 300℃,indicating improved ignition characteristics suitable for cofiring.Techno-economic analysis revealed a net profit of 138520 Indian rupees/year,with a payback period of 5 years and a benefit-cost ratio of 1.27,supporting the economic feasibility of the system.Overall,the study confirms that torrefied biomass presents improved fuel characteristics and combustion behaviour,making it a viable solution for clean-energy transition and sustainable waste management.
