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Yucca Mountain
High-level Nuclear
Waste Repository
Radiation Basics
CRWMS
CIVILIAN RADIOACTIVE WASTE MANAGEMENT SYSTEM
Function of the CRWMS is to "Dispose of Waste” directing
or controlling any physical activity, operation, or process to
accept title to and physical possession of spent fuel and
high-level waste, and transporting these wastes to an
interim facility (if authorized) for storage and the repository
for permanent disposal. Supporting the Dispose of Waste
function are three subfunctions that the CRWMS must
perform: Accept and Transport Waste, Store Waste, and
Emplace and Isolate Waste.
Nuclear Waste Policy Act and Amendments
1982 - NWPA = comprehensive legislation regarding spent
nuclear fuel and high-level waste disposal; many
options (ocean floor, polar ice, outer space, etc.)
EIS - Deep Underground Geologic Disposal = SAFEST
Site selection Process = 9 sites in 6 states initially
Site list reduced to 5; 3 approved for study:
Hanford, WA; Deaf Smith Co., TX; Yucca Mtn., NV
1987 - NWPA Amendments Act to direct DOE to study
one site: Yucca Mountain
(If found unsuitable, studies to be stopped immediately)
Lawrence Livermore
National Laboratory
Designs for highlevel nuclear wastes
of two types:
1) spent fuel from
nuclear power plants
2) borosilicate glass
containing other
high-level waste
1
2
Night view of the starter tunnel
LM300 drill rig
Environmental
Considerations
Geology of Yucca Mountain
• Geology
• Geohydrology
• Tectonics
• Seismology
• Volcanology
GOAL:
Performance Assessment
Rock Layers at Yucca Mountain
Unsaturated
Zone
Non-welded tuff
Welded tuff
Water table
Fault
Saturated
Zone
Tuff with zeolites
Welded tuff - rhyolite composition, SW Idaho
(plain light photomicrograph, ~4 mm view)
Molecular model of Clinoptilolite, a zeolite
mineral, K-rich variety of heulandite.
BM = Bare Mountain; WT-7; T-14 = Trench 14; BB = Busted Butte;
SC = Solitario Canyon; SR = Stagecoach Road fault
Aeromagnetic Survey
Across Crater Flat and Yucca Mtn
U.S. Geological Survey
---------------------------------------------------------------------Help locate and identify the sources of anomalies in the
Earth's magnetic field. Magnetic anomalies may be related
to near-surface geology or to geologic structural features
within the Earth's crust.
(Magnetic data may reveal the existence of faults, the distribution of stratigraphic units,
the presence of intrusive bodies, the thickness and shape of sedimentary basins, and
the depth to the bottom of magnetic sources. Magnetic anomalies will tend to form along
boundaries where there is a vertical offset of beds.)
Aeromagnetic Survey Data
USGS
Detailed Aeromagnetic Map
USGS
Earthquakes and Faults
Field investigations of faults,
monitoring of earthquakes, and tests
involving nuclear explosions at the NTS
suggest that underground structures
can withstand ground motion.
Trenches allow better exposure of
faults and help to understand the
history of movement.
Desert Climate - Deep Water Table
This makes it possible to put a repository about 300 meters
(1,000 feet) underground and still have it be about 240
meters (800 feet) above the water table.
Low Rainfall at Yucca Mountain
Precipitation
Evapotranspiration
Infiltration
Runoff
Unsaturated
Zone
Recharge
Recharge
Percolation
Water
Table
Saturated
Zone
~16 cm (6”) rainfall per year
small fraction available for infiltration
lateral diversion indicated
DEEP WATER TABLE
Thermohydrologic Modeling of Yucca Mountain
• One- and two- dimensional simulations of the unsaturated zone (UZ).
• Three-dimensional simulations of the saturated zone (SZ).
• Thermo-hydrologic response following emplacement of heat-generating
waste packages with an assumed heat load of 83 kW/acre.
Objectives
1) describe the different thermal regimes
2) assess the thermally driven alterations to the hydrologic conditions
3) quantify the time to return to ambient conditions, and
4) identify the most likely and significant scenarios that may lead to
radionuclide releases.
Heating of the repository occurs from approximately 0 to 1000 years, followed by cooling
for tens of thousands of years. A large boiling zone develops above the repository because
of buoyant convection, extending nearly 200 m above the repository between 500-1000 years.
The boiling zone collapses entirely after several thousand years, but the region continues to
cool for tens of thousands of years.
Volcanic Activity
Caldera Formation
The caldera complex,
the source of Yucca
Mountain's welded tuffs,
is about 20 miles across
and centered about 17
miles north of the
mountain.
Volcanic History
“Volcano that formed Yucca Mountain
is long extinct, but scientists are
studying seven small and long
inactive volcanoes in the Yucca
Mountain area. They want to
determine if one might erupt in the
next 10,000 years and if an eruption
might affect an underground nuclear repository. By studying
layers of soil and rock to learn about past volcanic activities,
scientists have been able to make predictions about the future.
The probability of a future volcanic eruption directly
intersecting a repository at Yucca Mountain is estimated to be
about one in 70,000,000 per year, as confirmed by an
independent panel of experts. This is in line with earlier
estimates by Project scientists.” source: OCRWM
Performance Assessment for Radioactive Waste Disposal
Yucca Mountain, Nevada
Simple drawings show an underground repository under different sets of
conditions that might occur during its period of performance.
Y’all come on in; make yourself at home…..