Ultra Low-Level Calibration Gas Generation by Multistage Dilution Techniques

2009 ◽  
pp. 301-301-19 ◽  
Author(s):  
DP Lucero
Keyword(s):  
Gas Generation ◽  
Low Level ◽  
Calibration Gas

The LLWR’s 2011 Environmental Safety Case

2011 ◽  
Author(s):  
Richard Cummings ◽  
Andrew J. Baker ◽  
Trevor Sumerling ◽  
John Shevelan ◽  
Amy Huntington
Keyword(s):  
Formal System ◽  
Environmental Safety ◽  
Management Control ◽  
Careful Examination ◽  
Supporting Evidence ◽  
Gas Generation ◽  
Low Level ◽  
The Future ◽  
Safety Case ◽  
Level 2

The UK’s Low Level Waste Repository Ltd submitted an Environmental Safety Case (ESC) for the disposal of low-level waste to the Environment Agency on the 1st of May 2011. The ESC is a major submission that will decide the future use of the Repository and has major implications for the success of the UK’s LLW Strategy and decommissioning programme. This paper provides an overview of the work that has been carried out to support the submission. Key aspects of this ESC include: • detailed investigations of existing disposals, based on careful examination of existing records and other investigations, including interviews with former operational staff; • analysis of uncertainties in future disposals; • modelling of the biogeochemical evolution of the disposal system, which provides understanding of the evolution of pH, Eh and gas generation and thence underpinning for radionuclide releases in groundwater and gas; • development of a 3-D groundwater flow model, calibrated against observed heads and with a detailed representation of the engineered features; • analysis of coastal erosion and its impacts; • a major focus on optimisation based on detailed technical studies; • a conclusion that existing disposals do not require remediation; • the choice of a concrete vault design with permeable side walls designed to avoid bathtubbing after the end of management control; • a comprehensive set of assessment calculations, including thorough analysis of uncertainties, which demonstrate consistency with the Environment Agency’s risk and dose guidance levels; • revision of the LLWR’s WAC, based in part on the use of the ‘sum of fractions’ approach; • the use of a safety case document structure that emphasises key safety arguments in a Level 1 document and provides supporting evidence in a series of Level 2 documents; • the provision of a Level 2 document that describes in detail how each aspect of the regulatory guidance has been addressed. In the future, the 2011 ESC will be maintained using a formal system of change control. It will be used as a tool for decision making concerning the future development of the LLWR and waste acceptance.

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 Corrosion Behavior of Iron and Aluminum Under Waste Disposal Conditions

1996 ◽  
Vol 465 ◽  
Author(s):  
R. Fujisawa ◽  
T. Cho ◽  
K. Sugahara ◽  
Y. Takizawa ◽  
Y. Horikawa ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Waste Disposal ◽  
Initial Period ◽  
Safety Analysis ◽  
Hydrogen Gas ◽  
Radioactive Waste Disposal ◽  
Gas Generation ◽  
Low Level ◽  
20 Nm

ABSTRACTThe generation of hydrogen gas from metallic waste in corrosive disposal environment is an important issue for the safety analysis of low-level radioactive waste disposal facilities in Japan. In particular iron and aluminum are the possibly important elements regarding the gas generation. However, the corrosion behavior of these metals has not been sufficiently investigated under the highly alkaline non-oxidizing disposal conditions yet.We studied the corrosion behavior of iron and aluminum under simulated disposal environments. The quantity of hydrogen gas generated from iron was measured in a closed cell under highly alkaline non-oxidizing conditions. The observed corrosion rate of iron in the initial period of immersion was 4 nm/year at 15 °C, 20 nm/year at 30 °C, and 200 nm/year at 45 °C. The activation energy was found to be 100 kJ/mol from Arrhenius plotting of the above corrosion rates.The corrosion behavior of aluminum was studied under an environment simulating conditions in which aluminum was solidified with mortar. In the initial period aluminum corroded rapidly with a corrosion rate of 20 mm/year. However, the corrosion rate decreased with time, and after 1,000 hours the rate reached 0.001 to 0.01 mm/year.Thus we obtained data on hydrogen gas generation from iron and aluminum under the disposal environment relevant to the safety analysis of low-level radioactive disposal facilities in Japan.

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.

scholarly journals The biogeochemistry of gas generation from low-level nuclear waste: Microbiological characterization during 18 years study under in situ conditions

2019 ◽  
Vol 105 ◽  
pp. 55-67 ◽  
Author(s):  
Minna Vikman ◽  
Kaisa Marjamaa ◽  
Mikko Nykyri ◽  
Joe S. Small ◽  
Hanna Miettinen ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Gas Generation ◽  
Low Level ◽  
In Situ Conditions

scholarly journals The biogeochemistry of gas generation from low-level nuclear waste: Modelling after 18 years study under in situ conditions

2017 ◽  
Vol 84 ◽  
pp. 360-372 ◽  
Author(s):  
Joe S. Small ◽  
Mikko Nykyri ◽  
Minna Vikman ◽  
Merja Itävaara ◽  
Liisa Heikinheimo
Keyword(s):  
Nuclear Waste ◽  
Gas Generation ◽  
Low Level ◽  
In Situ Conditions

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

Low-level lead exposure: Are there harmful effects?

1983 ◽  
Vol 28 (1) ◽  
pp. 79-79
Author(s):  
Claire B. Ernhart
Keyword(s):  
Lead Exposure ◽  
Low Level ◽  
Harmful Effects
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