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Title: RESULTS OF THE PERFORMANCE ASSESSMENT FOR THE CLASSIFIED TRANSURANIC WASTES DISPOSED AT THE NEVADA TEST SITE

Abstract

Most transuranic (TRU) wastes are destined for the Waste Isolation Pilot Plant (WIPP). However, the TRU wastes from the cleanup of US nuclear weapons accidents are classified for national security reasons and cannot be disposed in WIPP. The US Department of Energy (DOE) sought an alternative disposal method for these ''special case'' TRU wastes and from 1984 to 1987, four Greater Confinement Disposal (GCD) boreholes were used to place these special case TRU wastes a minimum of 21 m (70 ft) below the land surface and a minimum of 200 m (650 ft) above the water table. The GCD boreholes are located in arid alluvium at the DOE's Nevada Test Site (NTS). Because of state regulatory concerns, the GCD boreholes have not been used for waste disposal since 1989. DOE requires that TRU waste disposal facilities meet the US Environmental Protection Agency's (EPA's) requirements for disposal of TRU wastes, which are contained in 40 CFR 191. This EPA standard sets a number of requirements, including probabilistic limits on the cumulative releases of radionuclides to the accessible environment for 10,000 years. The DOE Nevada Operations Office (DOE/NV) has contracted with Sandia National Laboratories (Sandia) to conduct a performance assessment (PA) tomore » determine if the TRU waste emplaced in the GCD boreholes complies with the EPA's requirements. Sandia has completed the PA using all available information and an iterative PA methodology. This paper overviews the PA of the TRU wastes in the GCD boreholes [1]. As such, there are few cited references in this paper and the reader is referred to [1] and [2] for references. The results of the PA are that disposal of TRU wastes in the GCD boreholes easily complies with the EPA's 40 CFR 191 safety standards for disposal of TRU wastes. The PA is undergoing a DOE Headquarters (DOE/HQ) peer review, and the final PA will be released in FY2001 or FY2002.« less

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
774333
Report Number(s):
LA-UR-01-597
TRN: US0102611
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Feb 2001
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; CLASSIFIED INFORMATION; ALPHA-BEARING WASTES; NEVADA TEST SITE; NUCLEAR WEAPONS; PERFORMANCE; SAFETY ANALYSIS; RADIOACTIVE WASTE DISPOSAL; RADIOACTIVE WASTE FACILITIES

Citation Formats

J. COCHRAN, and ET AL. RESULTS OF THE PERFORMANCE ASSESSMENT FOR THE CLASSIFIED TRANSURANIC WASTES DISPOSED AT THE NEVADA TEST SITE. United States: N. p., 2001. Web.
J. COCHRAN, & ET AL. RESULTS OF THE PERFORMANCE ASSESSMENT FOR THE CLASSIFIED TRANSURANIC WASTES DISPOSED AT THE NEVADA TEST SITE. United States.
J. COCHRAN, and ET AL. Thu . "RESULTS OF THE PERFORMANCE ASSESSMENT FOR THE CLASSIFIED TRANSURANIC WASTES DISPOSED AT THE NEVADA TEST SITE". United States. doi:. https://www.osti.gov/servlets/purl/774333.
@article{osti_774333,
title = {RESULTS OF THE PERFORMANCE ASSESSMENT FOR THE CLASSIFIED TRANSURANIC WASTES DISPOSED AT THE NEVADA TEST SITE},
author = {J. COCHRAN and ET AL},
abstractNote = {Most transuranic (TRU) wastes are destined for the Waste Isolation Pilot Plant (WIPP). However, the TRU wastes from the cleanup of US nuclear weapons accidents are classified for national security reasons and cannot be disposed in WIPP. The US Department of Energy (DOE) sought an alternative disposal method for these ''special case'' TRU wastes and from 1984 to 1987, four Greater Confinement Disposal (GCD) boreholes were used to place these special case TRU wastes a minimum of 21 m (70 ft) below the land surface and a minimum of 200 m (650 ft) above the water table. The GCD boreholes are located in arid alluvium at the DOE's Nevada Test Site (NTS). Because of state regulatory concerns, the GCD boreholes have not been used for waste disposal since 1989. DOE requires that TRU waste disposal facilities meet the US Environmental Protection Agency's (EPA's) requirements for disposal of TRU wastes, which are contained in 40 CFR 191. This EPA standard sets a number of requirements, including probabilistic limits on the cumulative releases of radionuclides to the accessible environment for 10,000 years. The DOE Nevada Operations Office (DOE/NV) has contracted with Sandia National Laboratories (Sandia) to conduct a performance assessment (PA) to determine if the TRU waste emplaced in the GCD boreholes complies with the EPA's requirements. Sandia has completed the PA using all available information and an iterative PA methodology. This paper overviews the PA of the TRU wastes in the GCD boreholes [1]. As such, there are few cited references in this paper and the reader is referred to [1] and [2] for references. The results of the PA are that disposal of TRU wastes in the GCD boreholes easily complies with the EPA's 40 CFR 191 safety standards for disposal of TRU wastes. The PA is undergoing a DOE Headquarters (DOE/HQ) peer review, and the final PA will be released in FY2001 or FY2002.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2001},
month = {Thu Feb 01 00:00:00 EST 2001}
}

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  • In 1986, 21 m3 of transuranic (TRU) waste was inadvertently disposed in a shallow land burial trench at the Area 5 Radioactive Waste Management Site on the Nevada Test Site. U.S. Department of Energy (DOE) TRU waste must be disposed in accordance with Title 40, Code of Federal Regulations (CFR), Part 191, Environmental Radiation Protection Standard for Management and Disposal of Spent Nuclear Fuel, High-Level, and Transuranic Radioactive Wastes. The Waste Isolation Pilot Plant is the only facility meeting these requirements. The National Research Council, however, has found that exhumation of buried TRU waste for disposal in a deep geologicmore » repository may not be warranted when the effort, exposures, and expense of retrieval are not commensurate with the risk reduction achieved. The long-term risks of leaving the TRU waste in-place are evaluated in two probabilistic performance assessments. A composite analysis, assessing the dose from all disposed waste and interacting sources of residual contamination, estimates an annual total effective dose equivalent (TEDE) of 0.01 mSv, or 3 percent of the dose constraint. A 40 CFR 191 performance assessment also indicates there is reasonable assurance of meeting all requirements. The 40 CFR 191.15 annual mean TEDE for a member of the public is estimated to reach a maximum of 0.055 mSv at 10,000 years, or approximately 37 percent of the 0.15 mSv individual protection requirement. In both assessments greater than 99 percent of the dose is from co-disposed low-level waste. The simulated probability of the 40 CFR 191.13 cumulative release exceeding 1 and 10 times the release limit is estimated to be 0.0093 and less than 0.0001, respectively. Site characterization data and hydrologic process modeling support a conclusion of no groundwater pathway within 10,000 years. Monte Carlo uncertainty analysis indicates that there is reasonable assurance of meeting all regulatory requirements. Sensitivity analysis indicates that the results are insensitive to TRU waste-related parameters. Limited quantities of TRU waste in a shallow land burial trench can meet DOE performance objectives for disposal of TRU waste and contribute negligibly to disposal site risk. Leaving limited quantities of buried TRU waste in-place may be preferred over retrieval for disposal in a deep geologic repository.« less
  • Classified transuranic material that cannot be shipped to the Waste Isolation Pilot Plant in New Mexico is stored in Greater Confinement Disposal boreholes in the Area 5 Radioactive Waste Management Site on the Nevada Test Site. A performance assessment was completed for the transuranic inventory in the boreholes and submitted to the Transuranic Waste Disposal Federal Review Group. The performance assessment was prepared by Sandia National Laboratories on behalf of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office using an iterative methodology that assessed radiological releases from the intermediate depth disposal configuration against the regulatory requirementsmore » of the 1985 version of 40 CFR 191 of the U.S. Environmental Protection Agency. The transuranic materials are stored at 21 to 37 m depth (70 to 120 ft) in large diameter boreholes constructed in the unsaturated alluvial deposits of Frenchman Flat. Hydrologic processes that affect long- term isolation of the radionuclides are dominated by extremely slow upward rates of liquid/vapor advection and diffusion; there is no downward pathway under current climatic conditions and there is no recharge to groundwater under future ''glacial'' climatic conditions. A Federal Review Team appointed by the Transuranic Waste Disposal Federal Review Group reviewed the Greater Confinement Disposal performance assessment and found that the site met the majority of the regulatory criteria of the 1985 and portions of the 1993 versions of 40 CFR 191. A number of technical and procedural issues required development of supplemental information that was incorporated into a final revision of the performance assessment. These issues include inclusion of radiological releases into the complementary cumulative distribution function for the containment requirements associated with drill cuttings from inadvertent human intrusion, verification of mathematical models used in the performance assessment, inclusion of dose calculations from collocated low-level waste in the boreholes for the individual protection requirements, further assessments of engineered barriers and conditions associated with the assurance requirements, and expansion of documentation provided for assessing the groundwater protection requirements. The Transuranic Waste Disposal Federal Review Group approved the performance assessment for Greater Confinement Disposal boreholes in 2001 and did not approve the Application of the Assurance Requirements. Remaining issues concerned with engineered barriers and the multiple aspects of the Assurance Requirements will be resolved at the time of closure of the Area 5 Radioactive Waste Management Site. This is the first completion and acceptance of a performance assessment for transuranic materials under the U.S. Department of Energy self-regulation. The Greater Confinement Disposal boreholes are only the second waste disposal configuration to meet the safety regulatory requirements of 40 CFR 191.« less
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