Tom Enyeart

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)

• Safety experiment debris
• Primary isotopes transuranics, e.g., Pu, Am

• Physical form individual oxide particles and
  particles attached to rocks, silica glass, or
  other test component residuals
• Particle size 1 20 microns

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)

• Near-surface underground radioactive materials
• Primary isotopes residual fission products and
  activation products from weapons testing
• (e.g., Cs-137, Sr/Y-90)

• Underground leach fields for liquid wastes
• Pits and trenches that contain test debris

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

1. Weapons grade plutonium, principally Pu-239
2. 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)