Measures of Geologic Isolation

2004 ◽  
Vol 824 ◽  
Author(s):  
William M. Murphy
Keyword(s):  
Scientific Basis ◽  
Yucca Mountain ◽  
Radiation Doses ◽  
Spent Fuel ◽  
Carbon 14 ◽  
Decay Series ◽  
Regulatory Measures ◽  
Geologic Setting ◽  
High Level

AbstractIsolation in a geologic setting has been the generally favored solution to the high-level radioactive waste (HLW) problem since a scientific basis for nuclear waste management began to be formulated over half a century ago. Although general features of suitable settings have been enumerated, quantitative measures of the safety of geologic isolation of HLW are challenging to devise and to implement. Some regulatory measures of isolation for the proposed repository at Yucca Mountain, Nevada, have be devised and revised involving considerations of global releases, groundwater travel time, and time and space scales for isolation. In current Yucca Mountain specific regulations, the measure of long-term safety hinges on probabilistic estimates of radiation doses to the average member of a maximally exposed group of people living about 18 km down the groundwater flow gradient within 10,000 years after permanent closure of the repository. From another perspective, hydrogeochemical studies provide quantitative measures of system openness and the ability of geologic systems to isolate HLW. Hydrogeochemical data that bear on geologic isolation of HLW at Yucca Mountain include precipitation of radionuclides in stable mineralogical products of spent fuel alteration, ages of natural secondary mineralization in the mountain, uranium decay-series isotopic data for system openness, bomb-pulse isotope occurrences, and ambient carbon-14 distributions.

Risk-Based Evaluation of Long-Term Safety for a Yucca Mountain Repository Using the IMARC TSPA Code

2004 ◽  
Vol 824 ◽  
Author(s):  
John Kessler ◽  
Michael Apted ◽  
Matthew Kozak ◽  
Wei Zhou
Keyword(s):  
Radioactive Waste ◽  
System Performance ◽  
Yucca Mountain ◽  
Electric Power Research Institute ◽  
Performance Assessments ◽  
Total System ◽  
Spent Fuel ◽  
Waste Repository ◽  
High Level

AbstractThe Electric Power Research Institute (EPRI) has conducted independent total system performance assessments (TSPAs) of the proposed Yucca Mountain spent fuel and high-level radioactive waste repository for 15 years. EPRI uses its TSPA code, IMARC, currently in its eighth version. The major results of the IMARC-8 analyses are presented in this paper. In all of the situations evaluated by EPRI using IMARC-8, the results for the reference repository concept for Yucca Mountain are well within the regulatory criteria established in the applicable regulations, 10 CFR 63 and 40 CFR 197. Further analyses indicate that at least two of the repository barriers must fail to function as anticipated for dose risks to rise as much as one millirem per year (1/15th of the regulatory limit).

Evaporative Evolution of Carbonate-Rich Brines from Synthetic Topopah Spring Tuff Pore Water, YuccaMountain, NV

2004 ◽  
Vol 824 ◽  
Author(s):  
Mark Sutton ◽  
Maureen Alai ◽  
Susan Carroll
Keyword(s):  
Pore Water ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
Pore Waters ◽  
Starting Solution ◽  
Sequential Experiments ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Topopah Spring Tuff

AbstractThe evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the wastecontainers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95°C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25°C and 95°C our starting solution should evolve towards a high pH carbonate brine. Results at 95°C show that this solution evolves towardsa complex brinethat contains about 99 mol% Na+for the cations, and 71 mol% Cl-, 18 mol% ΣCO2(aq), 9 mol% SO42- for the anions. Initial modeling ofthe evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in predicting the evolution of carbonate-rich brines during evaporation.

Evaporative Evolution of Brines from Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV

2002 ◽  
Vol 757 ◽  
Author(s):  
Maureen Alai ◽  
Susan Carroll
Keyword(s):  
Pore Water ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Level Nuclear Waste ◽  
Series Of Experiments ◽  
High Level ◽  
Topopah Spring Tuff

ABSTRACTWe are investigating the evaporation of pore water representative of the designated high-level-nuclear-waste repository at Yucca Mountain, NV to predict the range of brine compositions that may contact waste containers. These brines could form potentially corrosive thin films on the containers and impact their long-term integrity. Here we report the geochemistry of a relatively complex synthetic Topopah Spring Tuff pore water that was progressively evaporated in a series of experiments. The experiments were conducted in a vented vessel in which HEPA filtered air flowed over the 95°C solution. Samples of the evaporating solution and the condensed vapor were taken and analyzed to determine the evolving water chemistry and gas volatility. The final solid was analyzed by X-ray diffraction.The synthetic Topopah Spring Tuff water evolved towards a complex brine that contained about 45 mol % Cl, 7 mol% NO3, 43 mol% Na, 4 mol % K, and less than 1 mol % each of SO4, Ca, Mg, HCO3 and Si. Trends in the solution data and identification of CaSO4 solids suggest that fluorite, carbonate, sulfate, and Mg-silicate precipitation minimize the corrosion potential of “sulfate type pore water” by removing F, Ca, and Mg during the early stages of evaporation.

Use of Level 1 PSA in the Frame of EPR Licensing

2014 ◽  
Author(s):  
Gabriel Georgescu ◽  
Patricia Dupuy ◽  
Francois Corenwinder
Keyword(s):  
Probabilistic Methods ◽  
Spent Fuel ◽  
Pressurized Water ◽  
Spent Fuel Pool ◽  
Level 1 ◽  
Water Reactors ◽  
High Level ◽  
Design Construction

The French “Technical Guidelines for the design and construction of the next generation of NPPs with Pressurized Water Reactors” specify that the safety demonstration has to be achieved in a deterministic way, supplemented by probabilistic methods. In this context, for the EPR reactor of Flamanville (EPR-FA3), the PSA has been used from the beginning of the design. In the frame of the application for commissioning of EPR-FA3, EdF has to provide an “as-build” full scope PSA for the reactor and for the spent fuel pool, covering the internal events, as well as the internal and external hazards of significant impact. Some of these probabilistic studies were developed and evolved during the EPR design (PSA for “internal events”, specific studies for practically eliminated sequences, long term accident sequences…) and were analysed by IRSN, as French Safety Authority (ASN) technical support, at different EPR project stages (initial design, detailed design, construction application….) leading to many design and studies improvements. Today, in order to make the analysis of the application for the commissioning of the EPR-FA3 reactor more effective, the “anticipated” analysis of this application is in progress in France. In this context, the updated versions of the level 1 probabilistic studies for internal events and hazards were analysed by IRSN in 2013. The results and conclusions of this analysis were presented by IRSN early 2014 during a dedicated meeting of French Standing Group of experts for Reactors safety (SGR). The paper presents the analysis performed by IRSN of EdF EPR-FA3 level 1 probabilistic studies, highlighting the role of PSA to the achievement of high level of safety of EPR reactor.

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