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Radiation Sources and Isotopes of Concern at the Nevada National Security Site

Radiation Sources and Isotopes of Concern at the Nevada National Security Site. Tom Enyeart Senior Nuclear Engineer NNSA Nevada Site Office Community Environmental Monitoring Program Workshop July 25, 2011. Legacy Radioactive Material. Aboveground test residuals

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Radiation Sources and Isotopes of Concern at the Nevada National Security Site

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  1. Radiation Sources and Isotopes of Concern at the Nevada National Security Site Tom Enyeart Senior Nuclear Engineer NNSA Nevada Site Office Community Environmental Monitoring Program Workshop July 25, 2011

  2. Legacy Radioactive Material • Aboveground test residuals • Primary isotopes: Cs-137 and Sr/Y-90 • Physical form: irregular shaped fused silica glass (a.k.a. Trinity glass) • Ranges in size from fraction of millimeters to several centimeters across

  3. Legacy Radioactive Material(continued) • Physical form: individual oxide particles and particles attached to rocks, silica glass, or other test component residuals • Particle size: 1 – 20 microns • Safety experiment debris • Primary isotopes: transuranics, e.g., Pu, Am

  4. Legacy Radioactive Material(continued) • Soil activation from aboveground testing • Primary isotopes: Eu-152, 154, 155 present as a result of neutron activation of stable Eu in soil • Contamination levels low and not a control issue

  5. Legacy Radioactive Material (continued) • Underground leach fields for liquid wastes • Pits and trenches that contain test debris • Near-surface underground radioactive materials • Primary isotopes: residual fission products and activation products from weapons testing (e.g., Cs-137, Sr/Y-90)

  6. Legacy Radioactive Material (continued) • Residuals from drilling and decontamination activities • Primary isotopes: residual fission products and activation products from weapons testing (e.g., Cs-137, Sr/Y-90) • Residual surface and subsurface contamination as a result of decontaminating equipment or post-shot drilling into subsurface test cavities • Residuals from ordinance tests involving depleted uranium • Primary isotopes: U-238, U-235, U-234 • Ranges from small particles to chunks weighing several pounds or more

  7. Legacy Radioactive Material (continued) • Underground testing residual source term • Primary isotopes: Tritium, Kr-85, Sr/Y-90, Cs-137, Pu • Mega-curies of radioactivity located mostly in Pahute Mesa, Yucca Flat and Frenchman Flat • With exception of tritium, most of the residual source term is thought to remain in the melt glass in the original cavity

  8. Special Nuclear Material • Weapons grade plutonium, principally Pu-239 • Highly enriched uranium, principally U-235 • Examples • Nuclear materials staged at Device Assembly Facility (DAF) • Sub-critical tests assembled at DAF, executed at U1a • Joint Actinide Shock Physics Experimental Research Facility (JASPER) target materials

  9. Radioactive Waste • Low-level and mixed low-level radioactive wastes received from off-site generators for disposal at Area 5 Radioactive Waste Management Site • Principal isotopes: tritium, Fe-55, Co-60, Zn-65, Sr/Y-90, Tc-99, Cs-137, Th isotopes, U isotopes, Pu isotopes

  10. Radioactive Waste (continued) • Transuranic wastes stored at the Area 5 Radioactive Waste Management Complex from 1974-2009 prior to disposal at WIPP • Principal isotopes: Am-241, Pu-238, Pu-239, Pu-240, Pu-241

  11. Sealed Radioactive Sources NNSA/NSO tenant organizations own approximately 400 sealed radioactive sources • Principal isotopes: Co-60, Ba-133, Cs-137, U-235, U-238, Am-241, Pu-239, Cm-244, Cf-252 • Range from micro-curie instrument check sources to kilo-curie Co-60 and Cs-137 sources • Accountable sealed radioactive sources are inventoried and leak tested every six months

  12. Radiation Generating Devices (RGDs) • RGDs include • Devices that must be electrically energized to produce ionizing radiation, e.g., X-ray machines • Sealed radioactive sources that emit radiation continuously • Examples of RGDs used at NNSS facilities • X-ray machines with energies up to 9 MeV (DAF) • Neutron generators with energies up to 14 MeV Dense Plasma Focus • 1,200 Ci Co-60 source (North Las Vegas, Bldg. A-1 source range)

  13. Offsite Detection for Potential Release Air Sampler Pressurized Ion Chamber Thermo Luminescent Dosimeter CEMP stations are designed to collect data to analyze the amount of radiation received as energy waves (gamma rays) and as radioactive particles (gross alpha and beta)

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