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Title: Long-Term Performance of Transuranic Waste Inadvertently Disposed in a Shallow Land Burial Trench at the Nevada Test Site

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 geologic 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 publicmore » 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
Authors:
;
Publication Date:
OSTI Identifier:
961545
Report Number(s):
DOE/NV/25946--734
TRN: US0903149
DOE Contract Number:
DE-AC52-06NA25946
Resource Type:
Conference
Resource Relation:
Conference: 54th Annual Meeting of the Health Physics Society; Minneapolis, MN; July 12-16, 2009
Research Org:
National Security Technologies, LLC (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NA)
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ALPHA-BEARING WASTES; CONTAMINATION; DOSE EQUIVALENTS; GROUND DISPOSAL; NEVADA TEST SITE; NUCLEAR FUELS; PROBABILITY; RADIATION PROTECTION; RADIOACTIVE WASTE MANAGEMENT; RADIOACTIVE WASTES; REGULATIONS; RELEASE LIMITS; SENSITIVITY ANALYSIS; SITE CHARACTERIZATION; WASTES; WIPP; SPENT FUELS transuranic, Nevada Test Site