DOE/NNSA Technical Research, Engineering, and Development
Technical Research, Engineering, and Development Services (TREDS) for the DOE/NNSA
DRI’s contract with the Department of Energy (DOE) is one of the Institute’s largest multi-disciplinary research programs, drawing from personnel in all three divisions. DRI contributes to nearly all of the DOE Nevada Field Office’s major programs, but in particular DRI applies its expertise to environmental restoration and waste management, for groundwater modeling and sampling, for environmental monitoring, science and technology development, natural resource planning for long-term stewardship, and for management of historic and cultural resources to nonproliferation and treaty verification applications.
Although much of DRI’s work for DOE is directed to the Nevada National Security Site, DRI also conducts research on other DOE and Department of Defense sites through its contract where the DOE Nevada Field Office has responsibilities. Much of the research has been collaboration with other organizations including Los Alamos, Livermore, and Sandia National Laboratories; with the U.S. Geological Survey; and with private sector companies including NSTec, Stoller, and Navarro.
828 underground nuclear tests were conducted at the Nevada National Security Site during the period of January 1951 through September 1992. Approximately 1/3 of these tests were conducted at or below the water table, depositing significant quantities of radionuclides that are potentially susceptible to transport via groundwater flow. The DOE funds a major program, the UGTA project, to understand the nature and extent of contamination in the saturated zone. The strategy for achieving this objective is dependent upon an iterative approach of field characterization followed by groundwater flow and contaminant transport modeling. The ultimate objective is to predict, with a high degree of confidence, where and how rapidly groundwater may transport contaminants and at what concentration. DRI supports this effort through a variety of projects that utilize geochemistry, geophysics, groundwater hydraulics, geostatistics, and groundwater modeling in the achievement of the research objectives.
DRI’s UGTA research endeavors fall into the following areas:
- Groundwater Recharge using the chloride mass balance approach as well as an integrated soil physics and vadose-zone modeling approach.
- Well hydraulics and aquifer testing. This includes the application and interpretation of a variety of geophysical tools for determining groundwater flow (as a function of depth) within boreholes under stressed (pumping) and unstressed (ambient) conditions.
- Laboratory investigations of parameters that affect the transport of radionuclides (sorption, matrix diffusion, glass surface area) as well as the measurement of dissolved organic carbon-14, oxygen-18, deuterium, and carbon-13.
- Geochemical modeling of isotopic and ionic tracers. Kinetic and mass-balance models utilize measures of naturally occurring tracers within the groundwater to constrain the results of groundwater flow models based upon potentiometric heads and the distribution of hydraulic conductivity.
- Modeling groundwater flow and transport. This project has previously focused on representing the spatial variability of hydrogeologic parameters and the development of efficient semi-analytical tools and is now moving into decision support analysis and numerical flow and transport modeling.
In addition, various personnel from DRI belong to and support the UGTA Technical Working Group. This group makes recommendations to DOE relative to scientific and technical studies that promote the effective closure of Corrective Actions Units (CAUs) on the Nevada National Security Site (NNSS) and ensure the continuing protection of public health.
The results of DRI’s effort are collaborative in nature and are often published jointly with the USGS, Lawrence Livermore and Los Alamos National laboratories as well various environmental contractors. These reports provide the basis for subsequent numerical modeling and support the Department of Energy in the decision making process requisite to the closure of sites impacted by underground nuclear testing.
Meteorological and micrometeorological methods and models are being developed that will estimate the health risk of various levels of contaminants in the soils on the NNSS. The estimation of the particle size distribution of the contaminants, with particular attention to particles in the respirable range, has been conducted using a suspended soil particle system. Resuspension studies utilizing a wind tunnel have been conducted to develop data on dust transport. These resuspension tests and studies will be conducted prior to, during, and after remediation. The pre-remediation tests serve as a baseline. Data gathered during excavation of the soils are used to evaluate the respiration risk to workers during remediation. Post remediation data is used to calculate risk under various land use scenarios from residual soil contamination that is left on the site.
DRI is beginning research on evaluating the effectiveness of in situ, surface soil treatments for preventing wind resuspension of soil contaminants by wind, or transport by sheet wash. If successful, such soil treatments could be a temporary or permanent alternative to excavation of excavation of contaminated soils and their disposal as low-level waste.
DRI is a member of the DOE Containment Evaluation Panel (CEP) that evaluates the design for every nuclear test and other large underground experiments conducted on the NNSS. The responsibility of the CEP is to comment on all aspects related to safe containment of underground nuclear tests. The primary activity of DRI for the CEP is to address the hydrologic implications of each test, as well as other aspects of the containment design. Since each test possesses unique features, the activities that are carried out vary from test to test and may include computer analyses of the data from past tests, including analyses of the geology and materials properties in and around the site of the proposed event, and comparison of these parameters with those of past events. DRI is also a member of the Containment Review Panel (CRP), which evaluates non-nuclear tests.
While no underground nuclear tests are currently being conducted, DOE must maintain the capability to return to testing if necessary. DOE has asked DRI to evaluate different methods of offsite monitoring should testing ever be resumed to ensure the safety of residents off the NNSS. The recent upgrade of the CEMP network, with capability of real-time and remote monitoring of sites, is an example of upgrades in monitoring capability that are being incorporated into plans. DRI is also evaluating the past dispersal of contaminants to determine pathways and receptors that would need to be monitored over a much wider area of the western United States. The WRCC is assisting in the identification of existing monitoring platforms that could be used if underground nuclear testing was resumed.
Community Environmental Monitoring Program (CEMP)
Since the inception of nuclear testing at the NTS, DOE has recognized the necessity of knowing the amount of radiation to which humans and the environment might be exposed. The objectives of the Community Environmental Monitoring Program (CEMP) include augmenting and enhancing collection of airborne radiation data at selected locations in the long-established monitoring network, and involving, in as many ways as possible, the residents of the area surrounding the NTS to increase their understanding of this and other DOE-sponsored activities. The commitment by DOE and the others associated with the program to the protection of the health and safety of these residents is the overriding consideration in the effort.
Beginning in 1999, DRI began a major overhaul of the CEMP stations. All stations have been upgraded with a full suite of meteorological equipment (anemometers, digital barometers, rain gauges, etc.) and new pressurized ion chambers where necessary. In addition, data loggers have been installed to allow for more reliable collection and backup of information. The principal means of communicating the collected meteorological and ambient radiological data is through a cellular phone/land line phone system and satellite systems linked to DRI’s Western Regional Climate Center (WRCC). Data from the 25 stations (located in communities around the NTS and as far east as Delta, Utah) in the network are uploaded regularly and displayed on a publicly-accessible web site on the WRCC home page. Currently, collected data are averaged at 10-minute intervals and web page data are updated every three to four hours for the majority of sites. If needed, stations can be remotely programmed to collect data at even more frequent intervals in the event of an emergency. Efforts are currently underway to equip stations that occur where DSL capabilities are present with modems that will allow direct connections to the internet, providing web data that is updated in near real-time. Monthly summaries of the network data are posted on large bulletin boards that DRI has installed at each community site.
Automation of the CEMP network has had scientific and educational benefits. For example, the ability to take measurements at high frequency allows correlations of ambient radiological readings with meteorological phenomena to be better evaluated. The availability of the information on the WRCC web site allows interested stakeholders, students, teachers, and scientists to independently evaluate patterns and trends at each station as well as to compare results across the network. DRI hopes that the CEMP network can even more effectively contribute to its science education initiatives, particularly in rural Nevada.
Lastly, DRI has further expanded the CEMP by incorporating annual monitoring for tritium in wells chosen by members of participating CEMP communities and ranches. Analytical results from wells located near particular stations are made available at the stations. This process helps to address the concerns of citizens living near the NTS who have apprehensions about potential impacts to their drinking water from past activities conducted on the NTS.
For more information, please visit the CEMP website: cemp.dri.edu
Patrick Sawyer, Ph.D.
Desert Research Institute
755 East Flamingo Road
Las Vegas, NV 89119
Earth and Ecosystem Sciences