Oxidative decomposition of ammonium ion with ozone in the presence of cobalt and chloride ions for the treatment of radioactive liquid waste

2021 ◽  
Vol 139 ◽  
pp. 103872
Author(s):  
Haruka Aihara ◽  
Sou Watanabe ◽  
Atsuhiro Shibata ◽  
Lina Mahardiani ◽  
Ryoichi Otomo ◽  
...  
1998 ◽  
Vol 13 (8) ◽  
pp. 2151-2160 ◽  
Author(s):  
A. Guerrero ◽  
S. Hérnandez ◽  
S. Goñi

The durability of a specific backfilling pozzolanic cement mortar, which is employed in Spain, in concrete containers for the storage of low (LLW) and medium level wastes (MLW), has been studied by means of the Köch–Steinegger test at the temperature of 40 °C during a period of 365 days. Mortar samples were immersed in a simulated radioactive liquid waste very rich in sulphate (0.68 M), phosphate (0.89 M), and chloride (0.51 M) ions. The changes of the microstructure were followed by x-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). Pore solution was extracted at different periods in order to see the changes of the chemical composition caused by the diffusion of those ions inside the microstructure.


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.


2002 ◽  
Vol 90 (3) ◽  
Author(s):  
Y. Sugo ◽  
Y. Sasaki ◽  
S. Tachimori

SummaryHydrolytic and radiolytic stabilities of a promising extractant, N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA), for actinides in high-level radioactive liquid waste from nuclear fuel reprocessing were investigated in air at room temperature. Hydrolysis by nitric acid was not observed, whereas radiolysis by gamma irradiation was notably observed. The radiolysis study showed that an amide-bond, an ether-bond, and a bond adjacent to the ether-bond tended to be broken by gamma irradiation, and dioctylamine and various N,N-dioctylmonoamides were identified as the main degradation products by GC/MS and NMR analyses. The


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