تبلیغات
منم! زکریای رازی! - process of recovery of Uranium from indst waste
www.facebook.com\peimanaliasghari
NRC7 - SEVENTH INTERNATIONAL CONFERENCE ON NUCLEAR AND RADIOCHEMISTRY 
 
Budapest, Hungary 24-29 August 2008 

A study on a process for recovery of uranium alone from spent nuclear fuel in a high alkaline carbonate media Kwang-Wook Kim

, Yeon-Hwa Kim, Seong-Min Kim, Heui-Seung Seo, Dong-Yong Chung m Yang, Jea-Kwan Lim, Kih-Soo Joe, Eil-Hee Lee
Korea Atomic Energy Research Institute, 150 Deokjin, Yuseong, Daejeon, 305-353, Republic of Korea

nkwkim@kaeri.re.kr
 
Abstract – A conceptual process to recover uranium alone from spent nuclear fuel in a high alkalin carbonate media with most of the fission products including TRU elements remaining undissolved in solid state in the solutio was studied. The process only used a few precipitation steps and an electrolytic recycle of used chemical salts.The process was evaluated to be helpful for the spent fuel management in views of a volume reduction of high level active waste and recycle of uranium in the spent fuel while greatly enhancing its proliferation-resistance and environmental friendliness.   
Keywords–Uranium, Dissolution, Carbonate, Precipitation   

I. INTRODUCTION 
Recently a great deal of interest has been shown on a complete recovery of uranium and minor actinide elements from spent nuclear fuel to reduce the toxicity of the radioactive elements and to increase the capacity of a disposal repository [1,2]. Most of wet processes studied over world usually adapt a complex combination of solvent extraction methods in acid media, which generates a lot of  organic and aqueous wastes and has a potential flammability.  
 In this work, a process for the purpose of recovery of only uranium from spent nuclear fuel with characteristics of a high proliferation-resistance and almost zero-release of waste was suggested. The process consisted of mainly three parts of an oxidative dissolution of U from the spent fuel by using saltfree oxidant of hydrogen peroxide, a recovery of the dissolved uranium by neutralization-hydrolysis precipitation, and an electrolytic recycle of the used salts., as shown in 

Fig.1.  
Oxidative dissolution of only U from SF in a high 
alkaline carbonate media Precipitates
(TRU, RE, etc) 
U & impurities  
(Tc, Cs, Mo, Te) 
UO44H2O Precipitates
Tc, Cs 
PrecipitatesPrecipitation of Tc, 
Cs by TPPCl, 
NaTPB  U, Mo, Te 
 Na2CO3
 NaOH 
Recovery of salt by electrodialysis  
 HNO3
Mo, Te disposal 
Precipitation of Uand recovery of carbonate salt  Fig.1 Conceptual diagram of a process to recover only U from a nuclear spent fuel in a strong alkaline carbonate media 

II. RESULT AND DISCUSSION 
In the dissolution stage of Fig.1,   U was evaluated  to be dissolved with a sufficiently fast dissolution rate and a high solubility in a sodium carbonate solution of 0.5 ~ 1 M solution at pH of 11~12 containing hydrogen peroxide of about 0.5 M together with dissolution of a few impurity elements of only Cs, Tc, Mo, Te from spent nuclear fuel. At this time, because of the differences in the solubilities and redox potentials of the radio-nuclides, most of  rare earth, TRU, and transient elements were evaluated or confirmed to 
be precipitated as insoluble residue or hydrolysates. The dissolved uranium was in a chemical form of uranyl peroxocabonate complex which was very stable and increased much the uranium solubility in the carbonate solution. The Cs and Tc could be selectively removed from the solution by precipitants of such as sodium tetraphenyl borate and tetraphenyl phosphoium chloride. The dissolved uranium could be recovered with a high precipitation yield of more than 99% by acidification of the solution to pH of 3 to 5 with adding acid in the solution or with using an electrolytic cell with a cation exchange membrane. During the acidification of 
the uranium carbonate solution, the de-carbonation and liberation of oxygen in uranyl peroxo-carbonate complex occurred.  The CO2 released during the acidification of the uranyl carbonate solution could be completely recovered as sodium carbonate by using a gas absorption column into which a NaOH solution was fed.  After the recovery step of uranium, all the chemical salts used in the process such as the carbonate salt, NaOH, and  acid could be almost completely recovered and recycled without any generation of secondary waste by using an electrodialysis  reactor where the Mo andTe were finally separated from the solution. During evaluation of the process, the redox potentials and the characteristics of solution chemistry of major elements in the spent nuclear fuel including TRU elements were investigated or examined in solutions with a variety of carbonate 

concentration and pH.   
Because of minimal generation of waste and the mixed precipitation of TRU elements together with other fission products without their dissolutions during recovery of U alone from the spent fuel, k, the process suggested in this work can said to be very helpful for the spent fuel management in view of a volume reduction of the high level active waste generated from the spent fuel with enhancing greatly the proliferation-resistance, environmental  friendliness, and operational safety. [1] Mathur, J.N., Murali, M.S., Nash, K.I., Solvent Extraction Ion Exchange, 19(3) 357 (2001).   [2] Vandegrift, G.F., et al, Atalanta 2004,
(France, June 21-25 (2004

www.chemicalboys,mihanblog.com      



فریاد زدم در تاریخ 1390/05/22 فریاد پیمان علی اصغری
درباره پیمان علی اصغری
آرام تر سکوت کن...
صدای بی تفاوتی هایت,
آزارم می دهد...
نیستی ببینی...
بعضی اوقات,
آنقدر حس تنهایی غرقم می کند,
که حتی خودم را هم,
دور و بر خودم نمی بینم...
هزگر نمی بخشمت...
پیمان علی اصغری
(ادمین سبز)
نظر سنجی
کاربرد این وبلاگ در چه سطحی قرار داره؟





فریاد
آرشیو فریادها
پیوندهای روزانه


    
قالب وبلاگ