233
and operate such devices already knows that an easy way to substantially increase
the yield is to detonate one on top of a nuclear powerplant. Thus, many valid reasons
remain for removing spent nuclear fuel from major cities and constructing an underground, high-level radioactive waste repository.
No technical issues have been identified that disqualify Yucca Mountain as a
high-level nuclear waste repository. It is located in the Mojave Desert in an area that
gets an average of four to 6 inches (10–15 cm) of rainfall in a year. It sits on government land, straddling the boundary between the Nevada National Security Site (formerly known as the Nevada Test Site), the Nellis Air Force Base bombing range,
and Bureau of Land Management (BLM) land.
About the only way nuclear materials could escape from a Yucca Mountain
repository is by being dissolved in groundwater and carried along with the flow. The
water table under Yucca Mountain is nearly 2000 ft (600 m) below the crest. This
creates a very thick unsaturated zone for storing nuclear waste in tunnels deep
underground but still high above the groundwater. Movement of groundwater percolating vertically through the unsaturated zone and then flowing laterally under the
mountain toward Death Valley is very slow, on the order of tens of thousands to
hundreds of thousands of years. Death Valley is a closed basin below sea level with
no connection to any other watersheds. Anything that ends up in Death Valley
stays there.
The mountain itself is a tilted fault block composed of layers of volcanic ash
called tuff that erupted some 12–13 Ma in the Late Miocene (Day et al. 1998) from
an unidentified, extinct volcanic caldera probably to the north. Several of these layers are so thick that the trapped heat caused the individual ash particles to fuse
together and form welded tuff, which is almost as hard as granite. As part of the site
characterization studies in the 1990s, a tunnel was excavated from north to south
beneath the crest of the mountain. Called the Exploratory Studies Facility or ESF,
the tunnel is five miles (8 km) in length by 25 ft (7.6 m) in diameter, and large
enough to handle shipments of high level radioactive waste (Fig. 12.2).
Politicians in the state of Nevada are almost uniformly opposed to using Yucca
Mountain as a high-level radioactive waste repository. The reasons for this have
much to do with the history of the nuclear waste program in the United States,
including some heavy handed decisions that seemed expedient at the time but later
turned out to be problematic.
When commercial nuclear power first became established in the mid-1950s, the
U.S. Congress set up a trust fund for dealing with the anticipated large volumes of
high-level radioactive waste. Income for the trust fund came from a tariff imposed
on nuclear-generated electricity. This fund was used to support the characterization
and design of a permanent repository for the high-level radioactive waste. When the
nuclear waste fund was established, it was expected that an operational repository
would be available to accept power plant waste by the early 1980s.
An underground repository option for high level waste had been recommended
by the National Academy of Sciences in 1957. The idea behind a “repository” was
that the waste could be monitored, and even retrieved if necessary due to corrosion
and leakage of a storage canister, or in case large stocks of fissionable materials
12.1 Technological Solutions
and operate such devices already knows that an easy way to substantially increase
the yield is to detonate one on top of a nuclear powerplant. Thus, many valid reasons
remain for removing spent nuclear fuel from major cities and constructing an underground, high-level radioactive waste repository.
No technical issues have been identified that disqualify Yucca Mountain as a
high-level nuclear waste repository. It is located in the Mojave Desert in an area that
gets an average of four to 6 inches (10–15 cm) of rainfall in a year. It sits on government land, straddling the boundary between the Nevada National Security Site (formerly known as the Nevada Test Site), the Nellis Air Force Base bombing range,
and Bureau of Land Management (BLM) land.
About the only way nuclear materials could escape from a Yucca Mountain
repository is by being dissolved in groundwater and carried along with the flow. The
water table under Yucca Mountain is nearly 2000 ft (600 m) below the crest. This
creates a very thick unsaturated zone for storing nuclear waste in tunnels deep
underground but still high above the groundwater. Movement of groundwater percolating vertically through the unsaturated zone and then flowing laterally under the
mountain toward Death Valley is very slow, on the order of tens of thousands to
hundreds of thousands of years. Death Valley is a closed basin below sea level with
no connection to any other watersheds. Anything that ends up in Death Valley
stays there.
The mountain itself is a tilted fault block composed of layers of volcanic ash
called tuff that erupted some 12–13 Ma in the Late Miocene (Day et al. 1998) from
an unidentified, extinct volcanic caldera probably to the north. Several of these layers are so thick that the trapped heat caused the individual ash particles to fuse
together and form welded tuff, which is almost as hard as granite. As part of the site
characterization studies in the 1990s, a tunnel was excavated from north to south
beneath the crest of the mountain. Called the Exploratory Studies Facility or ESF,
the tunnel is five miles (8 km) in length by 25 ft (7.6 m) in diameter, and large
enough to handle shipments of high level radioactive waste (Fig. 12.2).
Politicians in the state of Nevada are almost uniformly opposed to using Yucca
Mountain as a high-level radioactive waste repository. The reasons for this have
much to do with the history of the nuclear waste program in the United States,
including some heavy handed decisions that seemed expedient at the time but later
turned out to be problematic.
When commercial nuclear power first became established in the mid-1950s, the
U.S. Congress set up a trust fund for dealing with the anticipated large volumes of
high-level radioactive waste. Income for the trust fund came from a tariff imposed
on nuclear-generated electricity. This fund was used to support the characterization
and design of a permanent repository for the high-level radioactive waste. When the
nuclear waste fund was established, it was expected that an operational repository
would be available to accept power plant waste by the early 1980s.
An underground repository option for high level waste had been recommended
by the National Academy of Sciences in 1957. The idea behind a “repository” was
that the waste could be monitored, and even retrieved if necessary due to corrosion
and leakage of a storage canister, or in case large stocks of fissionable materials
12.1 Technological Solutions