scholarly journals Separation of Fission Products in High-Level Liquid Waste

2021 ◽  
Vol 37 (10) ◽  
pp. 1319-1320
Author(s):  
Akira OHASHI
2012 ◽  
Vol 560-561 ◽  
pp. 637-643
Author(s):  
Yong Li ◽  
Xue Gang Liu ◽  
Jin Chen

The proper management of spent fuel arising from nuclear power production is a key issue for the sustainable development of nuclear energy. While conventional reprocessing process, PUREX process, was successful to recover uranium and plutonium, in recent years some countries have turned to focus on advanced reprocessing process, which features of partitioning of minor actinides (MA) and long-lived fission products(LLFP). Most advanced reprocessing processes under development involve new extractants and additional extraction cycles. In China, TRPO extraction process has been developed to partition MA/LLFP from high-level liquid waste(HLLW) since early 1980’s. In parallel to R&D work on separation technologies, studies on concentration & denitration process have been evolved to prepare feed solutions to suit qualifications of extraction. Industrially, concentration & denitration is the internationally recognized standard to treat HLLW released from PUREX before vitrification. It enables to minimize the volume of interim storage, to restrain the corrosion of storage tank, to recover nitric acid in HLLW and to reduce the required evaporation duty of the vitrification process. Generally, the constitution of concentrated HLLW has little impact on the following vitrification process. But when concentration & denitration acts as pretreatment process of partitioning, the composition of actinides, fission products, and nitric acid in concentrated HLLW solution plays significant role in extraction process. A series of technical issues relevant to the connection between concentration ﹠denitration and extractions should be solved. This paper describes current status of concentration & denitration technology utilized in industry and under reprocessing plants. The specific separation requirements in advanced reprocessing process and challenges to apply concentration & denitration process are addressed. Besides, concentration & denitration process was tested in laboratory to adjust feed solutions for TRPO and Cyanex301 partitioning. Results demonstrate its promising prospect in advanced reprocessing process.


2012 ◽  
Vol 482-484 ◽  
pp. 58-61 ◽  
Author(s):  
Ming Fen Wen ◽  
Bo Yu ◽  
Min Luo ◽  
Jing Chen

The presence of long-lived radionuclides is a challenge to the management of high level liquid waste (HLLW). Separation of minor acitinides and long-lived fission products from the HLLW by partitioning process has the potential of significantly decreasing the costs of the immobilization and disposal of the radioactive waste by minimizing waste volumes. Several solvent extraction processes have been developed and demonstrated at the Institute of Nuclear and New Energy Technology (INET) for the separation of transuranic elements, 90Sr and 137Cs. In this work, using modified zeolite molecular sieve as a sorbent carrier, four kinds of solidification were prepared by soakage- absorption- calcination methods. It was found that the sample (HZCS-75) calcinated at 750°C was formed pollucite, a zeolite mineral, which will provide an option to immobilize the radioactive cesium and strontium.


2004 ◽  
Vol 92 (7) ◽  
Author(s):  
Laurent Couston ◽  
M. C. Charbonnel ◽  
J. L. Flandin ◽  
Christophe Moulin ◽  
F. Rancier

SummaryImprovement of the nuclear fuel reprocessing involves separating the minor actinides (Am(III) and Cm(III)) from the fission products. In the French strategy, the first step consists in the separation of the trivalent actinides and lanthanides from high-level liquid waste, for which malonamides RR´NCO(CHR´´)CONRR´ are promising ligands. These molecules have been optimized for reprocessing but still require basic chemical studies to describe the complexation mechanisms at a molecular scale. This paper discusses a thermodynamic and structural study of a Ln(III)-malonamide complex formed with the hydrosoluble tetraethylmalonamide ligand (TEMA=(C


Author(s):  
Isao Yamagishi ◽  
Masaki Ozawa ◽  
Hitoshi Mimura ◽  
Shohei Kanamura ◽  
Koji Mizuguchi

Fission reaction of U-235 and/or plutonium generates more than 40 elements and 400 nuclides in the spent fuel. Among them, 31 elements are categorized as rare metals. In a conventional fuel cycle U and Pu are reused but others are vitrified for disposal. Adv.-ORIENT (Advanced Optimization by Recycling Instructive Elements) Cycle strategy was drawn up for the minimization of radio-toxicity and volume of radioactive waste as well as the utilization of valuable elements/nuclides in the waste. The present paper describes the progress on Fission Products (FP) separation in this Cycle. Highly functional inorganic adsorbent (AMP-SG, silica gel loaded with ammonium molybdophosphate) and organic microcapsule (CE-ALG, alginate gel polymer enclosed with crown ether D18C6) were developed for separation of heat-generating Cs and Sr nuclides, respectively. The AMP-SG adsorbed more than 99% of Cs selectively from a simulated High-level Liquid Waste (HLLW). The ALG microcapsule adsorbed 0.0249 mmol/g of Sr and exhibited the order of its selectivity; Ba > Sr > Pd >> Ru > Rb > Ag. The electrodeposition is advantageous for both recovery and utilization of PGMs (Ru, Rh, Pd) and Tc because PGMs are recovered as metal on Pt electrode. Among PGMs, Pd was easily deposited on the Pt electrode. In the presence of Pd or Rh the reduction of Ru and Tc was accelerated more in hydrochloric acid media than in nitric acid. In the simulated HLLW, the redox reaction of Fe(III)/Fe(II) disturbed deposition of elements except for Pd. The deposits on Pt electrode showed higher catalytic reactivity on electrolytic hydrogen production than the original Pt electrode. The reactivity of deposits prepared from the simulated HLLW was higher than that from solution containing only PGM.


2009 ◽  
Vol 1193 ◽  
Author(s):  
E. Chauvin ◽  
C. Ladirat ◽  
R. Do Quang

AbstractIn 2008, AREVA NC Industrial Vitrification of High-Level Liquid Waste blows out its 30th candle, with always two main objectives during all the time: containment of the long lived fission products and reduction of the final volume of waste. During all this time AREVA with the French Atomic Energy Commission (CEA) developed and use in their industrial installations a selection of borosilicate glass that have been demonstrated as the most suitable containment matrix for waste from spent nuclear fuel. Consistent and long-term R&D programs associated to industrial feed back from operation have enabled continuous improvement of the process: throughput and waste loading factor enhancement. The Vitrification Process used and currently implemented in the AREVA facilities will be described.


2003 ◽  
Vol 792 ◽  
Author(s):  
V. Aubin ◽  
D. Caurant ◽  
D. Gourier ◽  
N. Baffier ◽  
S. Esnouf ◽  
...  

ABSTRACTProgress on separating the long-lived fission products from the high level radioactive liquid waste (HLW) has led to the development of specific host matrices, notably for the immobilization of cesium. Hollandite (nominally BaAl2Ti6O16), one of the main phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes consist of short-lived Cs and Cs of high activities and Cs with long lifetime, all decaying according to Cs+→Ba2++e- (β) + γ. Therefore, Cs-host forms must be both heat and (β,γ)-radiation resistant. The purpose of this study is to estimate the stability of single phase hollandite under external β and γ radiation, simulating the decay of Cs. A hollandite ceramic of simple composition (Ba1.16Al2.32Ti5.68O16) was essentially irradiated by 1 and 2.5 MeV electrons with different fluences to simulate the β particles emitted by cesium. The generation of point defects was then followed by Electron Paramagnetic Resonance (EPR). All these electron irradiations generated defects of the same nature (oxygen centers and Ti3+ ions) but in different proportions varying with electron energy and fluence. The annealing of irradiated samples lead to the disappearance of the latter defects but gave rise to two other types of defects (aggregates of light elements and titanyl ions). It is necessary to heat at relatively high temperature (T=800°C) to recover an EPR spectrum similar to that of the pristine material. The stability of hollandite phase under radioactive cesium irradiation during the waste storage is discussed.


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