Studies Of High-sufur?high-sodium?high Radioactivity Liquid Waste Vitrification Formulation

Storage of high level liquid waste of SEPEC poses a pollution threat to the environment,must be solidified into a stable form,so that in the long-term,safe storage.International high level liquid waste solidification treatment usually by vitrification method began in the 50's,vitrification has developed a number of techniques,calcined-melting tank law,Joule heating ceramic furnaces,Leng Ganguo law.Much international is the Joule heating ceramic furnace,electric furnace operation and management in foreign countries have had many success stories,but there are a lot of lessons.SEPEC study on vitrification formulations of high level liquid waste for a long time.Usually glass design and determined to take the following steps:?1?design glass performance requirements,?2?development of glass composition,and?3?experiment,test,to determine the composition,and?4?in the furnace for production testing.Glass preparation work for the VPC project has been awarded the industry standard in China is the main purpose of the characterization of radioactive waste,and waste packages under EJ1186-2005.It consists of the physical and chemical properties of the glass,the quality parameters and so on.And the high sodium content of sulfur in high level liquid waste,corrosion product concentration is also high.This gives us the desired oxide residue only slowly in the top reaction and melting the molten pool,which makes the slow formation kinetics of glass.Sulfur in silicate of boron lower solubility in molten mass,which causes waste glass containment capacity is limited to sulphur.Therefore,sulfur tolerant method of sodium borosilicate glass is very important to this project.Research work carried out in following systematically:First research work to pinpoint the determination solidified object-high level liquid waste processing.Second study,preliminary laboratory studies recommend the prescription of industrial scale bench run the Validate test.Investigation of a long running function;determination of industrial-scale glass unit processing capacity;determination of process performance and product quality evaluation of product homogeneity of glass melting and pouring,;research may appear at the top of the melt pool Huang Xiang;test repeatability.Third research work needed in the laboratory development of a borosilicate glass that will improve the ability of sulphur inclusion to achieve containment rate of at least 16wt%waste oxides in glass,appears at the top of the molten glass pool and avoid the accumulation of yellow and the ability to meet the required standards of waste glass.IV research work developed in the laboratory,in order to increase sulphur containment capacity of waste glass for process validation.By running the verification process:can be easily dissolved VPC simulation of sulfur in liquid waste;performance with the ease of glass melting;glass meet the specified quality requirements.According to high level liquid waste analysis test results show that high level liquid waste oxides in total 108g/l,oxide residues mainly composed of 4-n-oxide compositions,namely:Na₂O 45.1g/l,and Fe₂O₃ 19.7g/l,UO₂8.8/l,and Al₂O₃ 12.4 g/l.SO₃ content for 4.6g/l,the remaining 14.8 g/l of waste oxide is made up of 12 other oxides.In radiation chemistry of the most important components are:Cs₂O 0.73g/l,SrO 0.23 g/l.High level liquid waste containing 1.5mol/l of free nitric acid.Use of laboratory research featured in early formula,respectively in Germany and China conducted four rounds of cold running trials.Verify the test results show that:?1?the process plant processing capacity up to 45l/h;four-wheel-running data has good repeatability.?2?SEPEC higher sulfur content than the high level liquid waste,sulfur has failed to completely dissolve into the wastes in glass,in the form of Na₂SO₄,separated into liquid phase II?yellow phase?,floating on top of the molten glass pool,in concentration during the run up.?3?approximately one-third test of chemical stability of the samples failed to meet China's demand has been awarded the EJ1186-2005 provisions of the standard.?4?testing uniformity,transparency,glass surface quality are very good.Looking for glass have meet the requirements for sulphur containment capacity formula,this goal is not easy to achieve.Sulfur in glass melting and forming a tetrahedral structure for relatively large,they are not easily absorbed through the glass network.Key of waste glass composed design thought is:?1?waste glass composed in the,SiO₂ as main of glass network formed oxides,in Na₂O/?B₂O₃+Al₂O₃?of molecular than is greater than 1,B₂O₃ and Al₂O₃ with formed tetrahedron of composed conditions,up to fill network role,SiO₂,and B₂O₃ and Al₂O₃ to tetrahedron for structure unit composed not rules of continuous network,is waste glass of skeleton.?2?Li₂O,CaO,MgO and BaO etc basic oxide compositions produced mixed alkali effect is maintaining a good technological properties and the quality of waste glass,the glass network depolymerization,conducive to high level liquid waste oxides-inclusive.?3?add oxides such as Sb₂O₅ and V₂O₅,them as glass chemical reactions:SO₄^2-?O^2-+SO₂+1/2O₂ oxygen source,as far as possible in the form of SO₄^2-remain in the glass melt in the body,with more opportunities to network by inclusion into the glass,not in the form of SO₂ or SO₃ into the exhaust.Prepared a total of 180 in the laboratory glass,each containing samples of all waste oxide.Find improving sulphur containment capacity of chemical composition of glass,identified sulphur in the waste glass as seen in chemical form,sulfur tolerant ability to review promising waste glass composition,choose the candidate waste glass composition.Process parameters for waste glass for further measurements and quality parameters,waste glass formula slightly to make a number of improvements to the candidate,to meet the requirements of data in these improvements,waste glass of pre-selection.In the final step,waste glass composition on the preselection further minor improvements have been made,is the result of this work,determine the final waste glass-recommended formula.Last tests for verification of waste glass in Germany FZK-INE PVA.The glass formulation experiment was carried out in order to verify that the process under the scale of these key performance:can be easily dissolved in simulated waste sulfur;performance with ease of glass melting,glass and quality meet the requirements.Air bubble inclusion into the mixing device used to support accelerated sulfur Dynamics process of glass melting.Formed by bubbling tubes made of two Inconel690,immersing them in a glass level,a 3cm place,thus the bubble effect had been achieved,the glass melt is effectively mixed pools of the upper,and inclusion in molten sulfur in the body.In glass during recipe testing,completed 60 glass pouring.During the run,zero waste content of sulfur in glass from the beginning points towards the target level of growth,in treated 1.5m³VPC simulated waste,sulfur content is already in about0.7wt%SO₄^2-in the glass-like magnitude.After produce 3 containers of glass,is starting to reach target values for sulfur in glass?the target value is 0.816wt%?.Process and quality parameters of waste glass for the Chinese and German sides of the comparison of the two laboratories using the same testing method has completed,results on compliance with each other very well and data meet the defined requirements.Borosilicate glass containment capacity to sulphur,primarily depend on the chemical composition of glass.Cooling of sulfur in glass with SO₄^2-tetrahedron appears with two negative charges,negative charge mainly by melting the Na⁺cation balance in the body,and sulfur atoms and glass network without any coordination,it is isolated in the glass.Maintenance of 16wt%waste oxide inclusion rate and the waste sulfur in glass(in the form of SO₄^2-)the maximum concentration of 1.28wt%,technology,the inclusion of sulphur in the waste glass is fairly uniform,its contents could be achieved under simulated liquid sulfur concentration target value.Was not found during the test glass samples in a glass and pour into containers in isolation,yellow phase.