Study On Tritium Production Rate Measurement Of Breeding Blanket By Liquid Scintillation Counting Technique

The evaluation of the tritium breeding capability for a breeding blanket is one of the important topics for tritium self-sufficiency of a magnetic confinement fusion reactor based on D-T burning.To achieve the evaluation of tritium breeding capability,the key issue is the accurate measurement of the tritium production rate.In this paper,we studied the tritium production rate measurement by liquid scintillation counting technique and the preparation technology of liquid scintillation sample.The main contents and results of this paper are as follows:The distribution of production tritium in tritium breeding blanket with three different pellets was simulated.As results,tritium production decreased with the increase of tritium breeding blanket depth.The simulation study on the effect of encapsulation materials on tritium production by pellet was carried out.The results show that aluminum foil has the least impact for tritium production of pellet,aluminum foil package the pellet is a better choice.The simulation study on the effect of pellet size on tritium production by pellet was carried out.And the appropriate thickness of the pellet should be 1mm.The preparation method of liquid scintillation sample for tritium production rate measurement based on lithium carbonate pellet was studied.The lithium carbonate pellet dissolved by hydrochloric acid can produce liquid scintillation sample without liquid-liquid separation.Hydrochloric acid dosage should not overdose.Otherwise it will lead to liquid scintillation sample stratification and tritium counting efficiency decrease.The liquid scintillation sample prepared by sodium hydroxide and hydrochloric acid can keep clear fluid without the liquid-liquid separation.To improve tritium counting efficiency and with a good compatibility,liquid scintillation sample for 20 mL should keep least 12-mL liquid scintillation and the temperature during the process of preparation and measurement must be 10~20 centigrades.A method for preparing liquid scintillation sample of lithium orthosilicate pellet was developed.Lithium orthosilicate can dissolve by mixed acid under heated condition.Take a small part of the pellet solution and mixed with liquid scintillation can produce a liquid scintillation sample.The method of liquid scintillation sample preparation of lithium oxide pellet has been studied.In the case of lithium oxide pellet dissolved by hydrochloric acid will produce a lot of white smoke and a lot of energy,and may cause tritium escape.And lithium oxide pellet solution can be prepared a liquid scintillation sample without liquid-liquid stratified.The quenching correction method for the measurement of tritium production by liquid scintillation counting technique has been studied,and puts forward the improvement of the quenching correction method.This work is very important for accurate measurement of the tritium production rate.This paper analyzed the tritium escape during the preparation of liquid scintillation sample with improvement quenching correction method,and the experimental value of tritium escape rate was given.The Aluminum foil coated lithium carbonate pellet was irradiated with the reactor thermal neutron,and a preliminary experimental study on the production tritium measurement by liquid scintillation was carried out.However,due to the experimental conditions do not meet the experimental design,resulting in experimental data and simulation data are some differences,the need for further experimental study.