Development And Application Of Tritium Cycle Model For Pulsed Fusion Reactor

Tritium and deuterium fusion reaction requires the lowest fusion triple product to obtain fusion ignition condition,thus,this reaction be recognized as the most feasible way to achieve fusion energy.However,fusion reactor will consume tritium at a very large rate of 55.6kg/GW per full power year operation.Meanwhile,tritium resources on earth are scarce(3.5 kg)and uniformly exist in ocean or atmosphere which makes tritium cannot be supplied by nature resource.Consequently,tritium fuels supply be emphasized as the fundamental problem in fusion research.To obtain tritium from external resources is not only expensive but also strongly affected by authorities.To avoid these difficulties,existing fusion reactor designs produce tritium by blanket breeding.Researchers have designed a series of tritium fuel cycle to make the entire fusion system work correctly,at the same time,it brings issues like leakage,retention,safety problems etc.Consequently,it is essential to show solicitude for tritium cycle research,which includes:(1)Tritium self-sufficiency status will determine how long will the whole fusion system can operate,the amount of tritium bred should fill up all the losses caused by leakage,retention,decay,etc.(2)Tritium inventories in each subsystem are varied with time,respectively.These inventory curves must be monitored to avoid security problems,and to guide the accident analyses.(3)Minimum initial start-up inventory will affect the economy of the fusion reactor.Tritium cycle had been studied for decades all around the world,people have paid much attention to steady operation research,but couldn't emphasize the importance of pulsed operation research.However,pulsed scenarios should be successfully demonstrated before fusion reactor could operate under steady state,thus,tritium cycle research for pulsed fusion reactor should be viewed as equal.In order to figure out how pulsed model could affect the behavior of tritium cycle,it is really necessary to develop a new model to meet all the demands in pulsed fusion tritium cycle research.This work has developed a system dynamic model for tritium cycle of pulsed fusion reactor,which based on the newest research all around the world and mainly draws on the experience of ITER fuel cycle design,along with the addition of the module of tritium breeding blanket.This model not only can give the dynamic inventory changing curves in all subsystems but also rely on the behavior of tritium breeding and tritium consume to analyze the tritium self-sufficiency status and give the minimum initial start-up inventory results.The model was verified with TAS 1.0 and TRIMO.The former was applied for steady operation model verification,while the latter was used for pulsed model.The results show that the model can operate accurately and reliable.On the basis of tritium self-sufficiency influence factors,by merging the factors,which have the same influence on tritium cycle,finally achieved a simplified system dynamic tritium self-sufficiency analysis model.In this work representative design parameters of pulsed fusion reactors as the input parameters has been selected to make a tritium cycle simulation.Accurate trend curve of tritium inventory varying with operation time under different burning scenarios(burn time:450s,3000s;dwell time:450s/1350s,3000s/9000s)has been obtained.The analyses results show that burning scenarios will affect the conditioning strategy of first wall,and it also has influence on minimum initial start-up inventory.But it didn't show any sensitivity on required tritium breeding ratio.Afterwards,simplified system dynamic model was adopted to make sensitivity analyses in a reasonable range.Tritium breeding ratio and minimum initial startup inventory was used as the dependent variables.Results show that duty time,burnup fraction and saturation inventory are the key influence factors of TBRreq.While for minimum initial startup inventory burnup fraction and saturation inventory are of prime concern.For existing fusion technologies,burnup fraction,duty time still needed to be improved and saturation inventory should cut down to promise tritium self-sufficiency of future fusion reactor.