Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A compre...Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A comprehensive startup scheme for SNCLFR-100,including primary and secondary circuits,is proposed in this paper.It references existing more mature startup schemes in various reactor types.It additionally considers the restriction conditions on the power increase in other schemes and the characteristics of lead-based coolant.On this basis,the multi-scale coupling code ATHLET-OpenFOAM was used to study the flow instability in the startup phase under different power-step amplitudes and power duration times.The results showed that obvious flow instability phenomena were found in the different startup schemes,such as the short-term backflow phenomenon of the core at the initial time of the startup.Moreover,an obvious increase in the flow rate and temperature to the peak value at the later stage of a continuous power rise was observed,as well as continuous oscillations before reaching a steady state.It was determined that the scheme with smaller power-step amplitude and a longer power duration time requires more time to start the reactor.Nevertheless,it will be more conducive to the safe and stable startup of the reactor.展开更多
In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and t...In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained.展开更多
Motivated to understand the pressure-buildup characteristics in a circumstance of a water droplet immerged inside a heavy liquid metal pool,which is a key phenomenon during a Steam Generator Tube Rupture accident of L...Motivated to understand the pressure-buildup characteristics in a circumstance of a water droplet immerged inside a heavy liquid metal pool,which is a key phenomenon during a Steam Generator Tube Rupture accident of Lead-cooled Fast Reactor,many experiments have been conducted by injecting water lumps into a molten lead pool at Sun Yat-sen University.In order to deepen the understanding of the influence of melt material,this lead experiment was compared with a Lead-Bismuth-Eutectic(LBE)experiment in the literature.For both experiments,a steam explosion occurred in a small part of the experi-mental runs,which generally leads to strengthened pressure buildup.Regarding the non-explosion experimental cases,the impact of all parameters employed in lead experiments(i.e.,water lump volume,water lump shape,molten pool depth,and temperature of water and melt)on the pressure buildup is non-negligible and similar to that in our previous experiments using LBE.Notably,limited pressure buildup with an increase in water lump volume was also observed.A slightly more violent pressure buildup tends to appear in the lead experiments than in the LBE experiments under the same experimental conditions,which may be due to the higher thermal conductivity of lead than of LBE.In a few experimental runs with a relatively low melt temperature close to the melting point of lead,local solidification of liquid lead was observed,restricting pressure buildup.For the lead and LBE experiments,the calculated melt kinetic energy conversion efficiencyηhas a relatively small value(not exceeding 1.6%),and theηvalues have an overall positive correlation with the impulse on the molten pool.展开更多
文摘Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A comprehensive startup scheme for SNCLFR-100,including primary and secondary circuits,is proposed in this paper.It references existing more mature startup schemes in various reactor types.It additionally considers the restriction conditions on the power increase in other schemes and the characteristics of lead-based coolant.On this basis,the multi-scale coupling code ATHLET-OpenFOAM was used to study the flow instability in the startup phase under different power-step amplitudes and power duration times.The results showed that obvious flow instability phenomena were found in the different startup schemes,such as the short-term backflow phenomenon of the core at the initial time of the startup.Moreover,an obvious increase in the flow rate and temperature to the peak value at the later stage of a continuous power rise was observed,as well as continuous oscillations before reaching a steady state.It was determined that the scheme with smaller power-step amplitude and a longer power duration time requires more time to start the reactor.Nevertheless,it will be more conducive to the safe and stable startup of the reactor.
基金supported by Science and Technology on Reactor System Design Technology Laboratory,Chengdu,China(LRSDT2020106)
文摘In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained.
基金supported by the Basic and Applied Basic Research Foundation of Guangdong Province (Nos.2021A1515010343 and 2022A1515011582)the Science and Technology Program of Guangdong Province (Nos.2021A0505030026 and 2022A0505050029).
文摘Motivated to understand the pressure-buildup characteristics in a circumstance of a water droplet immerged inside a heavy liquid metal pool,which is a key phenomenon during a Steam Generator Tube Rupture accident of Lead-cooled Fast Reactor,many experiments have been conducted by injecting water lumps into a molten lead pool at Sun Yat-sen University.In order to deepen the understanding of the influence of melt material,this lead experiment was compared with a Lead-Bismuth-Eutectic(LBE)experiment in the literature.For both experiments,a steam explosion occurred in a small part of the experi-mental runs,which generally leads to strengthened pressure buildup.Regarding the non-explosion experimental cases,the impact of all parameters employed in lead experiments(i.e.,water lump volume,water lump shape,molten pool depth,and temperature of water and melt)on the pressure buildup is non-negligible and similar to that in our previous experiments using LBE.Notably,limited pressure buildup with an increase in water lump volume was also observed.A slightly more violent pressure buildup tends to appear in the lead experiments than in the LBE experiments under the same experimental conditions,which may be due to the higher thermal conductivity of lead than of LBE.In a few experimental runs with a relatively low melt temperature close to the melting point of lead,local solidification of liquid lead was observed,restricting pressure buildup.For the lead and LBE experiments,the calculated melt kinetic energy conversion efficiencyηhas a relatively small value(not exceeding 1.6%),and theηvalues have an overall positive correlation with the impulse on the molten pool.
