BNFL Lysimeter Proaramme to Investigate the Leachina of Radlonuclides from Low-Level Radioactive Waste

1992 ◽  
Vol 294 ◽  
Author(s):  
K. Clayton ◽  
R. Clegg ◽  
R.G.G. Holmes ◽  
G.W.A. Newton
Keyword(s):  
Radioactive Waste ◽  
Near Field ◽  
Analytical Data ◽  
Nuclear Fuels ◽  
Gas Generation ◽  
Effective Technique ◽  
Low Level ◽  
Leaching Behaviour ◽  
Radionuclide Release ◽  
Low Level Radioactive Waste

ABSTRACTBritish Nuclear Fuels ple has initiated an experimental programme to measure the leaching behaviour of radionuclides from various low level radioactive waste (LLW) mareials using Lysimeters. The programme commenced in 1986 and to date 10 lysimeters have been commissioned. These have concentrated on simulating shallow trench conditions but a further programme is now planned to study concrete vault environments. The aim of the study is to provide information on leaching processes as part of the ongoing Drigg Near Field Programme, and also to yield input data for radiological assessment purposes. Towards this end, data have been gained from the lysimeters on basic chemistry, gas generation and radionuclide Release Coefficients. This paper concentrates on one of the lysimeters which has recently been decommissioned and for which interim analytical data are available. Some general comments are given on BNFL's experience using lysimeters and their applicability as a rapid and effective technique for studying near field degradation processes.

The biogeochemical behaviour of U(VI) in the simulated near-field of a low-level radioactive waste repository

2006 ◽  
Vol 21 (9) ◽  
pp. 1539-1550 ◽  
Author(s):  
James R. Fox ◽  
Robert J.G. Mortimer ◽  
Gavin Lear ◽  
Jonathan R. Lloyd ◽  
Ian Beadle ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Near Field ◽  
Radioactive Waste Repository ◽  
Low Level ◽  
Waste Repository ◽  
Low Level Radioactive Waste

scholarly journals Near-field/Far-field Interface of a Near-Surface Low-Level Radioactive Waste Site

2003 ◽  
Vol 807 ◽  
Author(s):  
I. R. Beadle ◽  
J. Graham ◽  
S. Boult ◽  
V. L. Hand ◽  
P. Warwick ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Iron Hydroxide ◽  
Near Field ◽  
Experimental Studies ◽  
Far Field ◽  
Near Surface ◽  
Interface Zone ◽  
Low Level ◽  
Modelling Studies ◽  
Low Level Radioactive Waste

ABSTRACTExperimental and Modelling studies have been used to investigate the biogeochemical processes occurring at the interface zone between the near-field and far-field of the Drigg Low-Level radioactive Waste (LLW) trenches. These have led to a conceptual model of interface biogeochemistry, which has subsequently been modelled by the BNFL code known as the Generalised Repository Model (GRM). GRM simulations suggest that as organic rich leachate migrates into the far-field, iron III minerals such as iron hydroxide will dissolve, and reduced iron minerals such as siderite will precipitate due to microbial processes. Batch and column experimental studies have verified this conceptual understanding. Some unexpected processes, such as the presence of nitrate enhancing sulphate reduction, were also observed

Development of a New Mechanistic Low-Level Waste Source Term Model

1996 ◽  
Vol 465 ◽  
Author(s):  
Man-Sung Yim
Keyword(s):  
Source Term ◽  
Transport Model ◽  
Near Field ◽  
Cumulative Probability ◽  
Gas Generation ◽  
Low Level ◽  
Waste Forms ◽  
Term Model ◽  
Radionuclide Release ◽  
Source Term Model

ABSTRACTA new mechanistic low-level waste source term model was developed. Key features of this effort are: use of cumulative probability functions to describe the failures of waste containers; capability to describe diffusion controlled release which is dependent on the conditions of the waste package surroundings; consideration of the effects of gas generation on the source term, and; use of a source inventory characterization routine to provide a built-in capability for defining the distributions of radionuclides in various waste forms and streams. The model is capable of describing the diffusion of radionuclides in waste forms with the use of concentration and flux continuity boundary conditions. Release of radionuclides from various waste streams is modeled by the combination of diffusion, dissolution, and surface release. Failures of waste containers are portrayed by the use of probabilistic failure functions based on Weibull and lognormal distributions. The model for radionuclide release from waste packages is coupled with the near-field transport model to describe the effects of migration and dispersion within the disposal unit. Characteristics of the new model were evaluated through sensitivity analysis and compared with existing source term codes.

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