Evaluation of the Non-Transient Hydrologic Source Term from the CAMBRIC Underground Nuclear Test in Frenchman Flat, Nevada Test Site

Tompson, A B; Maxwell, R. M.; Carle, Steven F.; Zavarin, Mavrik; Pawloski, G A; Shumaker, D.E.

doi:10.2172/881893

Cited by 21 publications

(172 citation statements)

References 11 publications

(16 reference statements)

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“…To be conservative, allowing transport of a larger quantity of tritium, the modeling presented here assumes that none of the tritium is contained in the melt glass and thus all of the tritium produced is available for gas transport. This is consistent with source term modeling performed for underground nuclear tests at the Nevada Test Site (NTS) (Tompson et al, 1999).…”

Section: Conceptual Transport Modelsupporting

confidence: 86%

Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Cooper¹,

Ye²,

Chapman³

2008

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EXECUTIVE SUMMARYThe U.S. Department of Energy (DOE) and its predecessor agencies conducted a program in the 1960s and 1970s that evaluated technology for the nuclear stimulation of lowpermeability natural gas reservoirs. The second project in the program, Project Rulison, was located in west-central Colorado. A 40-kiltoton nuclear device was detonated 2,568 m below the land surface in the Williams Fork Formation on September 10, 1969. The natural gas reservoirs in the Williams Fork Formation occur in low permeability, fractured sandstone lenses interbedded with shale. Radionuclides derived from residual fuel products, nuclear reactions, and activation products were generated as a result of the detonation. Most of the radionuclides are contained in a cooled, solidified melt glass phase created from vaporized and melted rock that re-condensed after the test. Of the mobile gas-phase radionuclides released, tritium ( 3 H or T) migration is of most concern. The other gas-phase radionuclides ( 85 Kr, 14 C) were largely removed during production testing in 1969 and 1970 and are no longer present in appreciable amounts. Substantial tritium remained because it is part of the water molecule, which is present in both the gas and liquid (aqueous) phases.The objectives of this work are to calculate the nature and extent of tritium contamination in the subsurface from the Rulison test from the time of the test to present day (2007), and to evaluate tritium migration under natural-gas production conditions to a hypothetical gas production well in the most vulnerable location outside the DOE drilling restriction. The natural-gas production scenario involves a hypothetical production well located 258 m horizontally away from the detonation point, outside the edge of the current drilling exclusion area. The production interval in the hypothetical well is at the same elevation as the nuclear chimney created by the detonation, in order to evaluate the location most vulnerable to tritium migration.A three-dimensional geologic model was developed of the local Williams Fork Formation at the Rulison site that includes a sequence of sandstone and shale lenses conditioned on observations at two site wells. The dominant flow and transport direction is east-west, in agreement with the direction of regional fractures in the area. The average sandstone lens length is approximately 161 m, and mean thickness is 7.5 m. The sandstone lenses are characterized by very low intrinsic permeability in core measurements (on the order of 10 -18 m 2 ), while reservoir tests often indicate higher permeabilities (up to 10 -16 m 2 ) presumably as a result of fractures encountered at the field scale. Porosity of Williams Fork sandstone units is generally reported as being between 0.01 and 0.1. Shale units are considered barriers to flow, with intrinsic permeability of 10 -20 m 2 .A conceptual flow and transport model for the area around the emplacement well (where the nuclear device was located) was developed to investigate the rates of tritium transport in...

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Section: Conceptual Transport Modelsupporting

confidence: 86%

Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Cooper¹,

Ye²,

Chapman³

2008

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“…The radiologic source term is typically separated into two fractions: the exchange volume and the nuclear melt glass volume (Tompson et al, 1999(Tompson et al, , 2004(Tompson et al, , 2005Pawloski et al, 2001;SNJV, 2004SNJV, , 2005a. Spatially, the exchange volume is typically visualized as a spherical volume centered about the working point.…”

Section: Radionuclide Source Termmentioning

confidence: 99%

“…Given models M i and M j and their probabilities are P(M i ) and P(M j ), the probability odds are As a first example of the effectiveness of the analytical solution, the temperature history of the glass zone at the Cambric site is examined. Hydrologic source term simulations being conducted in fiscal year (FY) 2005 (Tompson et al, 2005) have examined the temperature history of the Cambric site at great detail. Although little direct information is available on the cooling history of the glass at the Cambric site, it is known that the glass zone temperature decreased to near ambient within 10 years of the test.…”

Section: Appendix a Recharge Model Elicitationmentioning

confidence: 99%

“…Although little direct information is available on the cooling history of the glass at the Cambric site, it is known that the glass zone temperature decreased to near ambient within 10 years of the test. This result was predicted based on nonisothermal flow and transport calculations conducted at Lawrence Livermore National Laboratory (Tompson, 2005). In these simulations, the initial glass zone temperature was set to the boiling temperature of water under hydrostatic conditions (170 °C) and both conductive and convective heat loss were simulated.…”

Section: Appendix a Recharge Model Elicitationmentioning

confidence: 99%

“…Details regarding the surface complexation and ion exchange modeling approach and the relevant surface complexation, ion exchange, and speciation constants can be found in those and other recent model validation efforts (Zavarin et al, 2002 Np,238,239,240,241,242 Pu, and 241 Am. The surface complexation of Ni was added only recently to the database of sorption reactions (see Tompson et al, 2005). The water chemistry and rock mineralogy used in the model are presented in detail below.…”

Section: Appendix a Recharge Model Elicitationmentioning

confidence: 99%

See 2 more Smart Citations

Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

Pohlmann¹,

Ye²,

Reeves³

et al. 2007

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Analysis of radionuclide migration through a 200-m Vadose zone following a 16-year infiltration event

Tompson

Hudson

Smith

2006

Advances in Water Resources

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The CAMBRIC nuclear test was conducted beneath Frenchman Flat at the Nevada Test Site on May 14, 1965. The nuclear device was emplaced in heterogeneous alluvium, approximately 70 m beneath the ambient water table, which is itself 220 m beneath the ground surface. Approximately 10 years later, groundwater adjacent to the test was pumped steadily for 16 years to elicit information on the migration of residual radionuclide migration through the saturated zone. The pumping well effluent -containing mostly soluble radionuclides such as tritium, Ru -was monitored, discharged to an unlined ditch, and allowed to flow towards Frenchman Lake over one kilometer away. Discharged water and radionuclides infiltrated into the ground and created an unexpected second experiment in which the migration of the effluent through the unsaturated zone back to the water table could be studied. In this paper, the pumping and effluent data are being utilized in conjunction with a series of geologic data, new radionuclide measurements, isotopic age-dating estimates, and vadose zone flow and transport models to better understand the movement of radionuclides between the ditch and the water table. Measurements of radionuclide concentrations in water samples produced from a water table monitoring well 100 m away from the ditch indicate rising levels of tritium since 1993. The detection of tritium in the monitoring well occurs approximately 16 years after its initial discharge into the ditch. Modeling and tritium age dating have suggested 3 to 5 years of this 16-year transit time occurred solely in the vadose zone. They also suggest considerable recirculation of the pumping well discharge back into the original pumping well. Notably, there have been no observations of 14 C or 85 Kr at the water table, suggesting their preferential retention or volatilization during transit to the water table. Overall, the long term nature of the experiment, the variety of chemical measurements and isotopic interpretations, and their incorporation into a unified modeling analysis, have contributed to a unique perspective for interpreting radionuclide migration in a deep unsaturated system. 2

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Evaluation of the Non-Transient Hydrologic Source Term from the CAMBRIC Underground Nuclear Test in Frenchman Flat, Nevada Test Site

Cited by 21 publications

References 11 publications

Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

Analysis of radionuclide migration through a 200-m Vadose zone following a 16-year infiltration event

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