radiation sources and isotopes of concern at the nevada national security site
Post on 31-Dec-2015
26 Views
Preview:
DESCRIPTION
TRANSCRIPT
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
Page 2Page 2Title83FY11 – 07/25/2011 – Page 2
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
Page 3Page 3Title83FY11 – 07/25/2011 – Page 3
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
Page 4Page 4Title83FY11 – 07/25/2011 – Page 4
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
Page 5Page 5Title83FY11 – 07/25/2011 – Page 5
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
Page 6Page 6Title83FY11 – 07/25/2011 – Page 6
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
Page 7Page 7Title83FY11 – 07/25/2011 – Page 7
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
Page 8Page 8Title83FY11 – 07/25/2011 – Page 8
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
Page 9Page 9Title83FY11 – 07/25/2011 – Page 9
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
Page 10Page 10Title83FY11 – 07/25/2011 – Page 10
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
Page 11Page 11Title83FY11 – 07/25/2011 – Page 11
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
Page 12Page 12Title83FY11 – 07/25/2011 – Page 12
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)
Page 13Page 13Title83FY11 – 07/25/2011 – Page 13
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)
top related