scholarly journals A Large Block Heater Test for High Level Nuclear Waste Management,

1994 ◽  
Vol 353 ◽  
Author(s):  
Wunan Lin ◽  
D. G. Wilder ◽  
J. A. Blink ◽  
S. C. Blair ◽  
T. A. Buscheck ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Near Field ◽  
Radioactive Decay ◽  
Test Site ◽  
Constant Load ◽  
Large Block ◽  
Field Environment ◽  
Before And After ◽  
Pressure Chemical ◽  
High Level

AbstractThe radioactive decay heat from nuclear waste packages may, depending on the thermal load, create coupled thermal-mechanical-hydrological-chemical (TMHC) processes in the near-field environment of a repository. A group of tests on a large block (LBT) are planned to provide a timely opportunity to test and calibrate some of the TMHC model concepts. The LBT is advantageous for testing and verifying model concepts because the boundary conditions are controlled, and the block can be characterized before and after the experiment. A block of Topopah Spring tuff of about 3 × 3 × 4.5 m was sawed and isolated at Fran Ridge, Nevada Test Site. Small blocks of the rock adjacent to the large block were collected for laboratory testing of some individual thermal-mechanical, hydrological, and chemical processes. A constant load of about 4 MPa will be applied to the top and sides of the large block. The sides will be sealed with moisture and thermal barriers. The large block will be heated by heaters within and guard heaters on the sides so that a dry-out zone and a condensate zone will exist simultaneously. Temperature, moisture content, pore pressure, chemical composition, stress, and displacement will be measured throughout the block during the heating and cool-down phases. The results from the experiments on small blocks and the tests on the large block will provide a better understanding of some concepts of the coupled TMHC processes. The progress of the project is presented in this paper.

scholarly journals Selection of Barrier Metals for a Waste Package in Tuff

1983 ◽  
Vol 26 ◽  
Author(s):  
E. W. yyRussell ◽  
R. D. McCright ◽  
W. C. O'Neal
Keyword(s):  
Nuclear Waste ◽  
Lawrence Livermore National Laboratory ◽  
Near Field ◽  
National Laboratory ◽  
Test Site ◽  
Management Program ◽  
Nuclear Waste Storage ◽  
Waste Storage ◽  
High Level ◽  
Selection Of

ABSTRACTThe Nevada Nuclear Waste Storage Investigations (NNWSI) project under the Civilian Radioactive Waste Management Program is planning a repository at Yucca Mountain at the Nevada Test Site for isolation of high-level nuclear waste. Lawrence Livermore National Laboratory is developing designs for an engineered barrier system containing several barriers such as the waste form, a canister and/or an overpack, packing, and near field host rock. In this paper we address the selection of metal containment barriers.

The Salton Sea Geothermal Field as a Natural Analog for the Near-Field in a Salt High-Level Nuclear Waste Repository

1984 ◽  
Vol 44 ◽  
Author(s):  
Wilfred A. Elders ◽  
Judith B. Moody
Keyword(s):  
Nuclear Waste ◽  
Near Field ◽  
Geothermal Field ◽  
Salton Sea ◽  
High Level Waste ◽  
Nuclear Waste Repository ◽  
Natural Analog ◽  
Naturally Occurring ◽  
Wide Range ◽  
High Level

AbstractThe Salton Sea Geothermal Field (SSGF), on the delta of the Colorado River in southern California, is being studied as a natural analog for the near-field environment of proposed nuclear waste repositories in salt. A combination of mineralogical and geochemical methods is being employed to develop a three dimensional picture of temperature, salinity, lithology, mineralogy, and chemistry of reactions between the reservoir rocks and the hot brines. Our aim is to obtain quantitative data on mineral stabilities and on mobilities of the naturally occurring radionuclides of concern in Commercial High-Level Waste (CHLW). These data will be used to validate the EQ3/6 geochemical code under development to model the salt near-field repository behavior.Maximum temperatures encountered in wells in the SSGF equal or exceed peak temperatures expected in a salt repository. Brines produced from these wells have major element chemistry similar to brines from candidate salt sites. Relative to the rocks, these brines are enriched in Na, Mn, Zn, Sr, Ra and Po, depleted in Ba, Si, Mg, Ti, and Al, and strongly depleted in U and Th. However the unaltered rocks contain only about 2–3 ppm of U and 4–12 ppm of Th, largely in detrital epidotes and zircons. Samples of hydrothermally altered rocks from a wide range of temperature and salinity show rather similar uniform low concentrations of these elements, even when authigenic illite, chlorite, epidote and feldspar are present. These observations suggest that U and Th are relatively immobile in these hot brines. However Ra, Po, Cs and Sr are relatively mobile. Work is continuing to document naturally occurring radionuclide partitioning between SSGF minerals and brine over a range of temperature, salinity, and lithology.

Application of Infrared Thermography to Non-Contact Testing of Varistors

2013 ◽  
Vol 20 (4) ◽  
pp. 677-688 ◽  
Author(s):  
Stanisław Galla ◽  
Alicja Konczakowska
Keyword(s):  
Electronic Devices ◽  
Infrared Camera ◽  
Constant Load ◽  
Test Results ◽  
Partial Loss ◽  
Protective Properties ◽  
Before And After ◽  
Nominal Voltage ◽  
High Level ◽  
Resistance Tests

Abstract Testing of varistors using thermography was carried out in order to assess their protective properties against possible overvoltage phenomena in the form of high-level voltage surges. An advantage of the thermography technique is non-contact temperature measurement. It was proposed to assess the properties of varistors working in electronic devices as protective elements, on the basis of estimating temperature increments on varistor surfaces, registered by an infrared camera during surge resistance tests with standard voltage levels. To determine acceptable temperature increments on a tested varistor, preliminary testing was performed of P22Z1 (Littelfuse) and S07K14 (EPCOS) type varistors, working first at a constant load and presently during surge tests,. The thermographic test results were compared with measured varistor capacity values before and after tests. It was found that recording with thermography temperature increments greater than 6°C for both P22Z1 and S07K14 varistor types detects total or partial loss of varistor protective properties. The test results were confirmed by assessment of protective properties of varistors working in output circuits of low nominal voltage devices.

(Invited) Surface Analysis of Corrosion Products Built up at Interfaces of Different Nuclear Waste Forms in Near-Field Environment

2020 ◽  
Vol MA2020-02 (12) ◽  
pp. 1282-1282
Author(s):  
Xiaolei Guo ◽  
Stephane Gin ◽  
Penghui Lei ◽  
Tiankai Yao ◽  
Hongshen Liu ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Nuclear Waste ◽  
Near Field ◽  
Corrosion Products ◽  
Waste Forms ◽  
Field Environment ◽  
Nuclear Waste Forms

scholarly journals Laser Photoacoustic Spectroscopy for Trace Level Detection of Actinides in Groundwater

1986 ◽  
Vol 84 ◽  
Author(s):  
Mark M. Doxtader ◽  
Victor A. Maroni ◽  
James V. Beitz ◽  
Michael Heaven
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Near Field ◽  
Trace Level ◽  
Field Environment ◽  
Waste Container ◽  
Laser Photoacoustic Spectroscopy ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Radionuclide Release

The Basalt Waste Isolation Project (Rockwell Hanford Operations- BWIP) is investigating the feasibility of building a repository in the Columbia River Basalts for the permanent disposal of high-level nuclear waste. One aspect of this effort is to develop an understanding of the chemical behavior of radionuclides in the near-field environment of the waste container. Such information is needed to determine radionuclide release rates from the waste package and to make long-term projections of repository performance. To accomplish this task, ultrasensitive laser- based techniques, such as laser photoacoustic spectroscopy (LPAS) and laser induced fluorescence (LIF), are being developed as analytical methods for the trace-level detection and speciation of actinides in solutions typical of those encountered in groundwaters near the BWIP repository.

The Influence of Thermal Gradients on the Long-Term Evolution of the Near-Field Environment of High-Level Nuclear Wastes Disposal

1997 ◽  
Vol 506 ◽  
Author(s):  
C. Poinssot ◽  
P. Toulhoat ◽  
B. Goffé
Keyword(s):  
Thermal Gradient ◽  
Near Field ◽  
Coupled Processes ◽  
Elemental Distribution ◽  
Thermal Gradients ◽  
Secondary Phases ◽  
Rock Interaction ◽  
Geochemical Model ◽  
Field Environment ◽  
High Level

ABSTRACTThe initial stage of some HLW disposal systems will be characterised by a large thermal pulse in the near-field environment, due to the heat of the radioactivity decay. This will lead to the development of a transient spatial thermal gradient between the hot canister and the cold geological medium, which could significantly affect the composition and the elemental distribution within the near-field environment. A coupled experimental and modelling work is presented in order to determine the influence of a thermal gradient on water-rock interaction processes. First experiments with a simulated nuclear glass evidenced mass transfer processes leading to chemical differentiation in the solid phases between the hot and the cold end of the system. The relevance of these experimental results to the case of a HLW disposal is strongly supported by in-situ experiments at Stripa, in which a realistic EBS under thermal gradient developed exactly the same mass transfers.In order to understand the driving force of these processes, we tried to model simplified experiments by using a mixing cell geochemical model built upon the geochemical code EQ3/EQ6. The discrepancies between modelling and experiments indicate the existence of coupled processes involving irreversible precipitation.Finally, thermal gradients were applied in nuclear glass-clay interaction experiments to enhance elemental migrations. The main results are: (i) a re-crystallisation of the initial clay toward a more silicic one through incorporation of elements released by the glass, (ii) a strong influence of clay chemistry on the nuclear glass secondary phases.

Model Calculations of Porosity Reduction Resulting From Cement-Tuff Diffusive Interaction

1997 ◽  
Vol 506 ◽  
Author(s):  
Peter C. Lichtner ◽  
Roberto T. Pabalan ◽  
Carl I. Steefel
Keyword(s):  
Reactive Transport ◽  
Near Field ◽  
Computer Code ◽  
Diffusive Transport ◽  
Geologic Repository ◽  
Model Calculations ◽  
Porosity Reduction ◽  
Field Environment ◽  
The Matrix ◽  
High Level

ABSTRACTTo determine the potential effects of alkaline plume migration on the near-field environment of the proposed high-level radioactive waste geologic repository at Yucca Mountain, Nevada, calculations are conducted simulating interactions between cement and tuff with pure diffusive transport of solute species. The calculations used the reactive transport submodule GEM of the computer code MULTIFLO [6]. The results suggest that strong alteration of the tuff host rock and of cement in contact with the tuff could result from these interactions. Porosity reduction within the tuff could isolate the matrix from fracture pore water. The model calculations predict calcification of the cement as would be expected. In simulations involving counter-diffusive transport across the cement-tuff contact, calcification is more pronounced in a partially-saturated environment compared to a fully-saturated one.

scholarly journals In-Situ Observation of the Alpha/beta Cristobalite Transition Using High Voltage Electron Microscopy

1989 ◽  
Vol 176 ◽  
Author(s):  
A. Meike ◽  
W. E. Glassley
Keyword(s):  
Water Vapor ◽  
High Voltage ◽  
Amorphous Silica ◽  
Near Field ◽  
In Situ Observation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Field Environment ◽  
High Level ◽  
Temperature Water

ABSTRACTA high temperature water vapor phase is expected to persist in the vicinity of high level radioactive waste packages for several hundreds of years. We have begun an investigation of the structural and chemical effects of water on cristobalite because of its abundance in the near field environment. A high voltage transmission electron microscope (HVEM) investigation of bulk synthesized α-cristobalite to be used in single phase dissolution and precipitation kinetics experiments revealed the presence β cristobalite, quartz and amorphous silica, in addition to α-cristobalite. Consequently, this apparent metastable persistence of β-cristobalite and amorphous silica during the synthesis of α-cristobalite was investigated using a heating stage and an environmental cell installed in the HVEM that allowed the introduction of either dry CO2 or a CO2 + H2O vapor. Preliminary electron diffraction evidence suggests that the presence of water vapor affected the α-β transition temperature. Water vapor may also be responsible for the development of an amorphous silica phase at the transition that may persist over an interval of several tens of degrees. The amorphous phase was not documented during the dry heating experiments.

scholarly journals Geochemistry of Natural Components in the Near-Field Environment, Yucca Mountain, Nevada

2006 ◽  
Vol 985 ◽  
Author(s):  
Zell E. Peterman ◽  
Thomas A. Oliver
Keyword(s):  
Pore Water ◽  
Nuclear Waste ◽  
Near Field ◽  
Major Elements ◽  
Yucca Mountain ◽  
Water Soluble ◽  
Nuclear Waste Repository ◽  
Chemical Compositions ◽  
Seepage Water ◽  
Field Environment

AbstractThe natural near-field environment in and around the emplacement drifts of the proposed nuclear waste repository at Yucca Mountain, Nevada, includes the host rock, dust, seepage, and pore water. The chemical compositions of these components have been analyzed to provide a basis for assessing possible chemical and mineralogical reactions that may occur after nuclear waste is emplaced. The rock unit hosting the proposed repository has a relatively uniform chemical composition as shown by samples with a mean coefficient of variation (CV) of 9 percent for major elements. In contrast, compositional ranges of underground dust (bulk and water-soluble fractions), pore water, and seepage water are large with mean CVs ranging from 28 to 64 percent for major constituents.

Incorporation of Cerium and Neodymium in a Uranyl Hydroxide Solid

2002 ◽  
Vol 713 ◽  
Author(s):  
C.W. Kim ◽  
D.J. Wronkiewicz ◽  
R.J. Finch ◽  
E.C. Buck
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Nuclear Waste ◽  
Spent Nuclear Fuel ◽  
Near Field ◽  
Nuclear Waste Repository ◽  
Migration Behavior ◽  
Spent Fuel ◽  
Field Environment ◽  
Waste Repository

ABSTRACTThe migration behavior of radionuclides in a nuclear-waste repository will be influenced, in part, by their equilibrium solubilities in the presence of radionuclide-bearing solids and/or adsorption affinities as trace components onto the surfaces of solid host phases. Uranium phases that precipitate on the surface of altered spent nuclear fuel may thus influence the mobility of radionuclides released in the near-field environment, since by proximity, these will be the first phases that the radionuclides encounter following their release from the spent fuel matrix.We have evaluated the potential for incorporating radionuclides into crystalline compounds by precipitating uranyl phases from aqueous solutions containing dissolved rare earth elements (REE; 2.1 ppm Ce4+, 4.6 ppm Ce4+, or 286 ppm Nd3+). Rare earth elements serve both as monitors for evaluating the potential behavior of REE radionuclides and as surrogate elements for the actinides (e.g., Ce4+ and Nd3+ for Pu4+ and Am3+, respectively). Although the crystalline compound that formed in the present set of experiments has not been positively identified, x-ray diffraction profiles suggest the presence of a uranyl hydroxide (UO2(OH)2) as the principal reaction product. An analysis of the crystalline products indicate a progressive decrease in concentration of cerium; from 26, to 20, and finally 11 ppm for crystals produced in 7-, 35-, and 190-day tests, respectively (Kd = 14, 11, 3, respectively). Results with neodymium display a similar trend, with concentrations in the solid decreasing from 1240 to 922 ppm between 7 and 35 days of reaction (Kd = 14 and 11, respectively). The decreasing concentration of REEs in the uranyl crystals can be correlated with both a coarsening in crystal size and a decrease in the concentration of dissolved uranium over time. Thus, REE incorporation in the crystalline solids decreases in conjunction with a decrease in the ratio of surface area/volume of the crystals, a decrease in the rate of crystal growth as uranium concentrations are lowered, or both. These data also suggest that adsorption of REE (and by analogy, actinides) onto crystal surfaces and subsequent trapping by crystal overgrowth processes may play key roles in the limiting the mobility of radionuclides in a nuclear waste repository.

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