Tom EnyeartSenior Nuclear EngineerNNSA Nevada Site Office

Community Environmental Monitoring Program WorkshopJuly 25, 2011

Radiation Sources and Isotopes of Concern at the

Nevada National Security Site

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Log No. 2011-225

Legacy Radioactive Material

1. 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

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Log No. 2011-225

Legacy Radioactive Material(continued)

2. 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

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Log No. 2011-225

Legacy Radioactive Material(continued)

3. Soil activation from aboveground testing• Primary isotopes:

Eu-152, 154, 155present as a resultof neutron activation of stable Eu in soil

• Contamination levelslow and not a controlissue

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Log No. 2011-225

Legacy Radioactive Material (continued)

4. 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

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Log No. 2011-225

Legacy Radioactive Material (continued)

5. 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

6. 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

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Log No. 2011-225

Legacy Radioactive Material (continued)

7. 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

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Log No. 2011-225

Special Nuclear Material1. Weapons grade plutonium, principally Pu-239

2. Highly enriched uranium, principally U-235

3. 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

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Log No. 2011-225

Radioactive Waste

1. 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

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Log No. 2011-225

Radioactive Waste (continued)

2. 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

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Log No. 2011-225

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

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Log No. 2011-225

Radiation Generating Devices (RGDs)

1. RGDs include

• Devices that must be electrically energized to produce ionizing radiation, e.g., X-ray machines

• Sealed radioactive sources that emit radiation continuously

2. 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)

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Log No. 2011-225

Offsite Detection for Potential ReleaseAir Sampler Pressurized

Ion ChamberThermo

LuminescentDosimeter

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)