scholarly journals An Application of Safety Assessment for Radioactive Waste Repository: Non-Equilibrium Transport of Tritium, Selenium, and Cesium in Crushed Granite with Different Path Lengths

2021 ◽  
Vol 11 (20) ◽  
pp. 9750
Author(s):  
Chuan-Pin Lee ◽  
Dongyang Chen ◽  
Yanqin Hu ◽  
Yi-Lin Jan ◽  
Yunfeng Shi ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Breakthrough Curves ◽  
Retardation Factor ◽  
Suitable Model ◽  
Advection Dispersion ◽  
Crushed Granite ◽  
Path Lengths ◽  
High Level ◽  
Non Equilibrium

Advection-dispersion experiments (ADE) were effectively designed for inadequate transport models through a calibration/validation process. HTO, selenium (Se), and cesium (Cs) transport in crushed granite were studied using a highly reliable, dynamic column device in order to obtain the retardation factors (R) and the dispersion coefficients (D) by fitting experimental breakthrough curves (BTCs) for various path lengths. In order to conduct a safety assessment (SA) of a deep geological repository for high-level radioactive waste, radionuclide transport in rock systems is necessary to clarify and establish a suitable model. A dynamic column with a radiotracer (HTO, Se(IV), and Cs) was applied to 2, 4, and 8 cm path lengths using a STANMOD simulation. The results showed similar results between the BTCs of Se and Cs by fitting a non-equilibrium sorption model due to the retardation effect. In fact, there was a relatively obvious sorption of Se and Cs in the BTCs obtained by fitting a retardation factor (R) value higher than 1. In addition, a two-region (physical) and a two-site (chemical) non-equilibrium model with either the lowest sum of squared residuals (SSQ) or the root mean square error (RMSE) were applied to determine the Se and Cs sorption mechanisms on granite.

Safety Assessment of Geological Disposal of High-Level Radioactive Waste in Boom Clay: Relation With the Radionuclide Inventory

2009 ◽  
Author(s):  
Pierre Van Iseghem ◽  
Jan Marivoet
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
High Level Waste ◽  
Spent Fuel ◽  
Geological Disposal ◽  
High Level Radioactive Waste ◽  
Boom Clay ◽  
High Level ◽  
Clay Formation ◽  
Parameter Values

This paper discusses the impact of the parameter values used for the transport of radionuclides from high-level radioactive waste to the far-field on the long-term safety of a proposed geological disposal in the Boom Clay formation in Belgium. The methodology of the Safety Assessment is explained, and the results of the Safety Assessment for vitrified high-level waste and spent fuel are presented. The radionuclides having the strongest impact on the dose-to-man for both HLW glass and spent fuel are 79Se, 129I, 126Sn, 36Cl, and 99Tc. Some of them are volatile during the vitrification process, other radionuclides are activation products, and for many of them there is no accurate information on their inventory in the waste form. The hypotheses in the selection of the main parameter values are further discussed, together with the status of the R&D on one of the main dose contributing radionuclides (79Se).

Modelling velocity and retardation factor of a nonlinearly sorbing solute plume

Soil Research ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 735 ◽  
Author(s):  
M. A. Mojid ◽  
H. Vereecken
Keyword(s):  
Travel Time ◽  
Power Law ◽  
Transport Process ◽  
Breakthrough Curves ◽  
Retardation Factor ◽  
Sodium Fluorescein ◽  
Local Velocity ◽  
Steady State Condition ◽  
Travel Path ◽  
Non Equilibrium

This study, considering evidences of slower sorption rates of reactive solutes in the field than in laboratory, quantifies the velocity and retardation factor of a sodium fluorescein (uranin: C20H10Na2O5) plume over its travel path in a heterogeneous aquifer. The transport process of uranin was evaluated by batch experiments and from breakthrough curves (BTCs) by using solute-transport models. Method of time moments analysed BTCs of uranin and bromide to derive the velocity and retardation factor. A constant velocity of the bromide plume, 0.64 m/day, implies a spatially and temporally uniform velocity field where groundwater flows at steady-state condition. A large dimensionless index (195) of chemical non-equilibrium model and equilibrium distribution coefficient (0.32) of uranin are indicative of chemical non-equilibrium transport process. The travel time of uranin plume increases asymptotically, following power law, with travel path of the plume. Good agreement of the exponent of power law with that of Freundlich isotherm is a result of nonlinear sorption, and provides an independent way of estimating the exponent of the isotherm. The local velocity of the plume decreases asymptotically in time and is predicted by the derivative of the relationship between travel path and travel time of the plume. The retardation factor, which increases in time following power law, when estimated from the local velocity, is considerably larger than that estimated from travel time of the plume.

Evaluated and Estimated Solubility of Some Elements for Performance Assessment of Geological Disposal of High-Level Radioactive Waste Using Updated Version of Thermodynamic Database

2010 ◽  
Author(s):  
Akira Kitamura ◽  
Reisuke Doi ◽  
Yasushi Yoshida
Keyword(s):  
Radioactive Waste ◽  
Performance Assessment ◽  
Safety Assessment ◽  
Thermodynamic Database ◽  
Energy Agency ◽  
Geological Disposal ◽  
High Level Radioactive Waste ◽  
Five Elements ◽  
High Level ◽  
Aqueous Species

Japan Atomic Energy Agency (JAEA) established the thermodynamic database (JAEA-TDB) for performance assessment of geological disposal of high-level radioactive waste (HLW) and TRU waste. Twenty-five elements which were important for the performance assessment of geological disposal were selected for the database. JAEA-TDB enhanced reliability of evaluation and estimation of their solubility through selecting the latest and the most reliable thermodynamic data at present. We evaluated and estimated solubility of the 25 elements in the simulated porewaters established in the “Second Progress Report for Safety Assessment of Geological Disposal of HLW in Japan” using the JAEA-TDB and compared with those using the previous thermodynamic database (JNC-TDB). It was found that most of the evaluated and estimated solubility values were not changed drastically, but the solubility and speciation of dominant aqueous species for some elements using the JAEA-TDB were different from those using the JNC-TDB. We discussed about how to provide reliable solubility values for the performance assessment.

Hydrolysis of trivalent plutonium and solubility of Pu(OH)3(am) under electrolytic reducing conditions

2016 ◽  
Vol 45 (48) ◽  
pp. 19449-19457 ◽  
Author(s):  
Hye-Ryun Cho ◽  
Young-Sang Youn ◽  
Euo Chang Jung ◽  
Wansik Cha
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Safety Assessment ◽  
Radioactive Waste Disposal ◽  
Reducing Conditions ◽  
System P ◽  
High Level ◽  
Hydrolysis Of

This paper focusses on the determination of the thermodynamic data of Pu(iii) hydrolysis, which are important for a long-term safety assessment of high-level radioactive waste disposal in a deep geological system.

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