scholarly journals Surrogate Model Development of Spent Fuel Degradation for Repository Performance Assessment.

2020 ◽  
Author(s):  
Paul Mariner ◽  
Timothy Berg ◽  
Kyung Chang ◽  
Bert Debusschere ◽  
Rosemary Leone ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Surrogate Model ◽  
Model Development ◽  
Spent Fuel

Surrogate Model Development for Naturally Ventilated Office Buildings

2020 ◽  
Author(s):  
Marcelo Salles Olinger ◽  
Ana Paula Melo ◽  
Letícia Oliveira Neves ◽  
Roberto Lamberts
Keyword(s):  
Surrogate Model ◽  
Model Development ◽  
Office Buildings

scholarly journals Spent Fuel as a Waste Form - Data Needs to Allow Long Term Performance Assessment Under Repository Disposal Conditions.

1986 ◽  
Vol 84 ◽  
Author(s):  
V. M. Oversby
Keyword(s):  
Performance Assessment ◽  
Waste Form ◽  
High Level Waste ◽  
Detailed Knowledge ◽  
Spent Fuel ◽  
Expected Performance ◽  
High Level ◽  
Term Performance ◽  
Physical And Chemical ◽  
Waste Repositories

AbstractPerformance assessment calculations are required for high level waste repositories for a period of 10,000 years under NRC and EPA regulations. In addition, the Siting Guidelines (IOCFR960) require a comparison of sites following site characterization and prior to final site selection to be made over a 100,000 year period. In order to perform the required calculations, a detailed knowledge of the physical and chemical processes that affect waste form performance will be needed for each site. While bounding calculations might be sufficient to show compliance with the requirements of IOCFR60 and 40CFRI91, the site comparison for 100,000 years will need to be based on expected performance under site specific conditions. The only case where detailed knowledge of waste form characteristics in the repository would not be needed would be where radionuclide travel times to the accessible environment can be shown to exceed 100,000 years. This paper will review the factors that affect the release of radionuclides from spemt fuel under repository conditions, summarize our present state of knowledge, and suggest areas where more work is needed in order to support the performance assessment calculations.

REPRO: Through Diffusion Experiment (TDE) - Diffusion and Porosity Properties of Rock Matrix in Stress Field of Repository Level

2020 ◽  
Author(s):  
Kalle Rahkola ◽  
Antti Poteri ◽  
Lasse Koskinen ◽  
Peter Andersson ◽  
Kersti Nilsson ◽  
...  
Keyword(s):  
Stress Field ◽  
Performance Assessment ◽  
Spent Nuclear Fuel ◽  
Diffusion Experiment ◽  
Spent Fuel ◽  
Tracer Transport ◽  
Rock Matrix ◽  
Safety Case ◽  
Through Diffusion

<p>Radionuclides usually migrate slower than the flowing water due to sorption and matrix diffusion. The performance assessment assumes that retention takes place mostly in the vicinity of the deposition holes. REPRO (<em>REtention Properties of ROck matrix</em>) experiments analyzed the matrix retention properties of the rock matrix under realistic conditions deep in the bedrock in ONKALO underground characterization facility at Olkiluoto, Finland. The objective was to investigate tracer transport in the rock matrix, which was representative to the near-field of the final disposal repository of the spent nuclear fuel, and to demonstrate that the assumptions made in the safety case of the deep geological spent fuel repository were in line with site evidence.</p><p>REPRO is composed of several supporting laboratory and <em>in-situ</em> experiments which investigate the retention properties under different experimental configurations. The first <em>in-situ</em> experiments were water phase diffusion experiments performed 2012-2013. Through Diffusion Experiment (TDE) studies diffusion and porosity properties of rock matrix in stress field of repository level and sorption properties of nuclides in intact rock circumstances.</p><p>The TDE experiment has been performed in three parallel drillholes drilled near to each other. Breakthrough of the radioactive tracer is monitored with on-line measurements and samplings along and perpendicular to the foliation. The non-sorbing radioactive isotope traces of HTO and <sup>36</sup>Cl, as well as slightly sorbing <sup>22</sup>Na and strongly sorbing <sup>133</sup>Ba and <sup>134</sup>Cs were used. TDE was designed to control advective flow, as it had caused problems in previous <em>in-situ</em> tests.</p><p>Supporting laboratory studies were performed for drillcore samples sampled from the experimental drillholes. In these laboratory experiments, i.e. porosity, permeability and diffusion coefficients of the drillcores were determined using different methods.</p><p>The TDE experiment was carried out from 2016 to 2019. A breakthrough was seen in the timeframe predicted by scoping calculations carried out. REPRO has produced data and knowledge to the safety case and the performance assessment. According to the preliminary results, values measured in the laboratory are applicable also in larger scale and <em>in-situ</em> conditions.</p>

scholarly journals Elements Present in Leach Solutions from Unsaturated Spent Fuel Tests

1993 ◽  
Vol 333 ◽  
Author(s):  
P. A. Finn ◽  
J. K. Bates ◽  
J. C. Hoh ◽  
J. W. Emery ◽  
L D. Hafenrichter ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Radionuclide Transport ◽  
Spent Fuel ◽  
Major Fraction ◽  
Transport Models ◽  
Preliminary Results ◽  
J 13

ABSTRACTPreliminary results for the composition of the leachate from unsaturated tests at 90°C with spent fuel for two successive periods of ~60 days each with pretreated J-13 groundwater are reported. The pH of the leachate solutions ranged from 4 to 7. The americium concentration was 104 to 105 greater than that reported for saturated spent fuel tests in which the leachate pH was 8. The major fraction of material in the leachate was present as colloids containing both americium and curium. The presence of actinides in a form not currently directly included in repository radionuclide transport models provides information that can be used in spent fuel reaction modeling, the performance assessment of the repository and the design of the engineering barrier system.

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