skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Fire as a long-term stewardship issue for soils contaminated with radionuclides in the western U.S

Abstract

On both U.S. Department of Energy (DOE) and U.S. Department of Defense sites in the southwestern United States (U.S.), significant areas of surface soils are contaminated with radionuclides from atmospheric nuclear testing, and with depleted uranium, primarily from military training. At DOE sites in Nevada, the proposed regulatory closure strategy for most sites is to leave contaminants in place with administrative controls and periodic monitoring. Closure-in-place is considered an acceptable strategy because the contaminated sites exist on access-restricted facilities, decreasing the potential risk to public receptor, the high cost and feasibility of excavating contaminated soils over large areas, and the environmental impacts of excavating desert soils that recover very slowly from disturbance. The largest of the contaminated sites on the Tonopah Test Range in Nevada covers over 1,200 hectares. However, a factor that has not been fully investigated in the long-term stewardship of these sites is the potential effects of fires. Because of the long half-lives of some of the contaminants (e.g., 24,100 years for {sup 239}Pu) and changes in land-cover and climatic factors that are increasing the frequency of fires throughout the western U.S., it should be assumed that all of these sites will eventually burn, possibly multiple times,more » during the time frame when they still pose a risk. Two primary factors are contributing to increased fire frequency. The first is the spread of invasive grasses, particularly cheat grass (Bromus tectorum and Bromus rubens), which have out-competed native annuals and invaded inter-spaces between shrubs, allowing fires to burn easier. The second is a sharp increase in fire frequency and size throughout the western U.S. beginning in the mid-1980's. This second factor appears to correlate with an increase in average spring and summer temperatures, which may be contributing to earlier loss of soil moisture and longer periods of dry plant biomass (particularly from annual plants). The potential risk to site workers from convective heat dispersion of radionuclide contaminants is an immediate concern during a fire. Long-term, post-fire concerns include potential changes in windblown suspension properties of contaminated soil particles after fires because of loss of vegetation cover and changes in soil properties, and soil erosion from surface water runoff and fluvial processes. (authors)« less

Authors:
; ; ; ; ; ;  [1]
  1. Desert Research Institute, 755 East Flamingo Road, Las Vegas, Nevada, 89119 (United States)
Publication Date:
Research Org.:
American Society of Mechanical Engineers (ASME), Three Park Avenue, New York, NY 10016-5990 (United States); Technological Institute of the Royal Flemish Society of Engineers (TI-K VIV), Het Ingenieurshuis, Desguinlei 214, 2018 Antwerp (Belgium); Belgian Nuclear Society (BNS) - ASBL-VZW, c/o SCK-CEN, Avenue Hermann Debrouxlaan, 40 - B-1160 Brussels (Belgium)
OSTI Identifier:
21156362
Resource Type:
Conference
Resource Relation:
Conference: ICEM'07: 11. International Conference on Environmental Remediation and Radioactive Waste Management, Bruges (Belgium), 2-6 Sep 2007; Other Information: Country of input: France; 28 refs.; Proceedings may be ordered from ASME Order Department, 22 Law Drive, P.O. Box 2300, Fairfield, NJ 07007-2300 (United States)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; BIOMASS; BURNS; DEPLETED URANIUM; ENVIRONMENTAL IMPACTS; FIRES; GRAMINEAE; PLUTONIUM 239; SHRUBS; SOILS; TONOPAH TEST RANGE

Citation Formats

Shafer, David S., DuBois, David, Etyemezian, Vic, Kavouras, Ilias, Miller, Julianne J., Nikolich, George, and Stone, Mark. Fire as a long-term stewardship issue for soils contaminated with radionuclides in the western U.S. United States: N. p., 2007. Web.
Shafer, David S., DuBois, David, Etyemezian, Vic, Kavouras, Ilias, Miller, Julianne J., Nikolich, George, & Stone, Mark. Fire as a long-term stewardship issue for soils contaminated with radionuclides in the western U.S. United States.
Shafer, David S., DuBois, David, Etyemezian, Vic, Kavouras, Ilias, Miller, Julianne J., Nikolich, George, and Stone, Mark. Sun . "Fire as a long-term stewardship issue for soils contaminated with radionuclides in the western U.S". United States. doi:.
@article{osti_21156362,
title = {Fire as a long-term stewardship issue for soils contaminated with radionuclides in the western U.S},
author = {Shafer, David S. and DuBois, David and Etyemezian, Vic and Kavouras, Ilias and Miller, Julianne J. and Nikolich, George and Stone, Mark},
abstractNote = {On both U.S. Department of Energy (DOE) and U.S. Department of Defense sites in the southwestern United States (U.S.), significant areas of surface soils are contaminated with radionuclides from atmospheric nuclear testing, and with depleted uranium, primarily from military training. At DOE sites in Nevada, the proposed regulatory closure strategy for most sites is to leave contaminants in place with administrative controls and periodic monitoring. Closure-in-place is considered an acceptable strategy because the contaminated sites exist on access-restricted facilities, decreasing the potential risk to public receptor, the high cost and feasibility of excavating contaminated soils over large areas, and the environmental impacts of excavating desert soils that recover very slowly from disturbance. The largest of the contaminated sites on the Tonopah Test Range in Nevada covers over 1,200 hectares. However, a factor that has not been fully investigated in the long-term stewardship of these sites is the potential effects of fires. Because of the long half-lives of some of the contaminants (e.g., 24,100 years for {sup 239}Pu) and changes in land-cover and climatic factors that are increasing the frequency of fires throughout the western U.S., it should be assumed that all of these sites will eventually burn, possibly multiple times, during the time frame when they still pose a risk. Two primary factors are contributing to increased fire frequency. The first is the spread of invasive grasses, particularly cheat grass (Bromus tectorum and Bromus rubens), which have out-competed native annuals and invaded inter-spaces between shrubs, allowing fires to burn easier. The second is a sharp increase in fire frequency and size throughout the western U.S. beginning in the mid-1980's. This second factor appears to correlate with an increase in average spring and summer temperatures, which may be contributing to earlier loss of soil moisture and longer periods of dry plant biomass (particularly from annual plants). The potential risk to site workers from convective heat dispersion of radionuclide contaminants is an immediate concern during a fire. Long-term, post-fire concerns include potential changes in windblown suspension properties of contaminated soil particles after fires because of loss of vegetation cover and changes in soil properties, and soil erosion from surface water runoff and fluvial processes. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jul 01 00:00:00 EDT 2007},
month = {Sun Jul 01 00:00:00 EDT 2007}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • This paper describes a pilot study that resulted in the generation of draft planning documents for the upcoming transition from remediation construction to long-term stewardship at three national laboratories managed by the U.S. Department of Energy (DOE)-Chicago Operations Office (CH). The remediation construction work at these facilities is being completed under the DOE's Office of Environmental Management (EM) Program. Once the remediation is complete, the responsibility for long-term stewardship (LTS) of the closed waste sites is expected to be transferred to the DOE organization responsible for managing each of the three facilities (i.e., the site landlord). To prepare for thismore » transfer, an extensive planning effort is required. This pilot study utilized the DOE guidance in effect at the time to (1) develop a series of documents identifying applicable requirements that the LTS Programs will need to satisfy, issues that need to be resolved before the transfer can proceed, and criteria to be used to determine when active remediation is complete and a given site is ready for transfer to the LTS Program; (2) examine alternate structures for possible LTS Programs; and (3) develop draft LTS Implementation Plans. This advanced planning effort yielded a number of observations and lessons learned that are applicable to any facility approaching the end of its remediation construction phase.« less
  • A definition of Long-Term Stewardship (LTS) is: "all activities required to protect human health and the environment from hazards remaining after cleanup is complete". "Cleanup" in this sense may mean completion of a prescribed remedy for contaminated soil or buried waste, or it could mean entombment of a nuclear facility or placing nuclear materials in safe, long-term storage. Among the activities included in this definition are long-term monitoring and surveillance, maintenance of engineered barriers, operation and maintenance of long-term remedies (such as groundwater pump and treat operations), institutional controls (e.g., deed restrictions, land use restrictions, permanent markers, etc.), and informationmore » management (including intergenerational transfer of data on residual hazards). The magnitude of the U.S. Department of Energy’s (DOE) LTS commitments, in terms of scope, cost, and time, is beginning to be better understood.« less
  • The U.S. Department of Energy (DOE) has managed the Long Term Stewardship and Maintenance activities at DOE sites since 1988. DOE's Office of Legacy Management (LM) was established in December 2003, and its specific mission is to manage the DOE's post-closure responsibilities and ensure the future protection of human health and the environment. LM has control and custody for legacy land, structures, and facilities and is responsible for maintaining them at levels suitable for their long-term use. LM uses DOE Policy 454.1: Use of Institutional Controls (ICs) and Associated Guidance. Many major Federal laws, Executive Orders, regulations, and various othermore » drivers influence the establishment and use of ICs at LM sites. LM uses a wide range of ICs as part of efforts to appropriately limit access to, or uses of, land, facilities and other real and personal property assets; protect the environment; maintain the physical safety and security of DOE facilities; and prevent or limit inadvertent human and environmental exposure to residual contaminants and other hazards. ICs generally fall into one of four categories identified by EPA guidance, and DOE is successfully using a 'defense in depth' strategy which uses multiple mechanisms to provide 'layering' for additional durability and protectiveness: - Proprietary controls - such as easements and covenants. - Governmental controls - implemented and enforced by state or local governments. - Enforcement and permit tools with IC components - such as CERCLA agreements or RCRA permits. - Informational devices - such as state registries or public advisories. An additional practice that supports ICs at LM sites entails the use of engineered controls, such as fences, gates, access controls, etc. to ensure public access to applicable areas is limited. An engineered control that is not an IC is the disposal cell itself with its design criteria that protects the contaminated interior, controls the penetration of precipitation, and the provides a physical barrier to environmental and biological intrusion. Other site engineered controls manage surface runoff, restrict access, and provide a monitoring network to track residual contamination and ensure the integrity of the remedy. These engineered controls are part of the remedy and are not considered to be Institutional Controls. As of fiscal year 2006, LM has long-term surveillance and maintenance (LTS and M) responsibilities at 70 sites in 27 states and Puerto Rico with 23 sites planned for transfer to the office during Fiscal Year 2007. ICs are in place at approximately 44 of the current LM sites and they are being tracked to ensure their integrity. A formal inspection process is used at many LM sites to confirm that remedial action components, including associated ICs, remain in place and are effective. Inspections are also critical for determining if additional maintenance or monitoring is necessary. Inspections may be conducted on an as-needed basis and frequencies can vary widely depending on site-specific policies and conditions, but typically occur on an annual basis. At CERCLA sites, the annual inspections are also incorporated into the Five-Year Review process. Inspection procedures are developed for each site and may contain the following components: - Development an inspection checklist based on previous findings or progressive changes in site conditions. - Physical inspection of engineered structures designed to contain or control waste materials. - Review of completed maintenance work and determination of maintenance needs. - Formal inspection of the physical location of IC areas to ensure continued protection of human health and the environment. - Contact of property owners to ensure continued awareness of ICs on their property. - Inspection of the IC areas to ensure that any restrictions imposed by the IC are not being violated, such as drilling of wells in an area that has groundwater restrictions. - Check of county records to verify that deed notices, easements, and other recorded instruments remain in place. - Preparation of report documenting inspection proceedings and schedule for completion of corrective actions, if any. The inspection process is a successful mechanism for ensuring effectiveness of ICs that allow protection of human health and the environment. As the LM site inventory grows to 131 sites by the year 2015, development and management of ICs will continue as an increasingly critical component of LTS and M programs. (authors)« less
  • The long-term stability of near-surface containment systems designed for the management of radioactive wastes and residues contaminated with naturally occurring radionuclides are compared at the three different sites. The containment designs are: (1) a diked 8.9-m high mound, including a 3.2-m layered cap at a site (humid) near Lewiston, New York, (2) a 6.8-m-high mound, including a similar 3.2-m cap at a site (humid) near Oak Ridge, Tennessee, and (3) 4.8-m deep trenches with 3.0-m backfilled caps at a site (arid) near Hanford, Washington. Geological, hydrological, and biological factors affecting the long-term (1000-year) integrity of the containment systems at eachmore » site are examined, including: erosion, flooding, drought, wildfire, slope and cover failure, plant root penetration, burrowing animals, other soil-forming processes, and land-use changes. For the containment designs evaluated, releases of radon-222 at the arid site are predicted to be several orders of magnitude higher than at the two humid sites - upon initial burial and at 1000 years (after severe erosion). Transfer of wastes containing naturally occurring radionuclides from a humid to an arid environment offers little or no advantage relative to long-term stability of the containment system and has a definite disadvantage in terms of gaseous radioactive releases. 26 references, 3 figures, 4 tables.« less
  • About 11,000 m/sup 3/ of uranium ore residues and 180,000 m/sup 3/ of wastes (mostly slightly contaminated soils) are consolidated within a diked containment area at the Niagara Falls Storage Site (NFSS) located about 30 km north of Buffalo, NY. The residues account for less than 6% of the total volume of contaminated materials but almost 99% of the radioactivty. The average /sup 226/Ra concentration in the residues is 67,000 pCi/g. Several alternatives for long-term management of the wastes and residues are being considered, including: improvement of the containment at NFSS, modification of the form of the residues, management ofmore » the residues separately from the wastes, management of the wastes and residues at another humid site (Oak Ridge, TN) or arid site (Hanford, WA), and dispersal of the wastes in the ocean. Potential radiological risks are expected to be smaller than the nonradiological risks of occupational and transportation-related injuries and deaths. Dispersal of the slightly contaminated wastes in the ocean is not expected to result in any significant impacts on the ocean environment or pose any significant radiological risk to humans. It will be necessary to take perpetual care of the near-surface burial sites because the residues and wastes will remain hazardous for thousands of years. If controls cease, the radioactive materials will eventually be dispersed in the environment. Predicted loss of the earthen covers over the buried materials ranges from several hundred to more than two million years, depending primarily on the use of the land surface. Groundwater will eventually be contaminated in all alternatives; however, the groundwater pathway is relatively insignificant with respect to radiological risks to the general population. A person intruding into the residues would incur an extremely high radiation dose.« less