Yucca Mountain straddles the west boundary
of the Nevada Test Site in an arid, remote, and
thinly populated region of southwestern Nevada.
It is the potential site of a monitored geologic repository
for the Nation’s commercial and military
spent nuclear fuel, high-level radioactive waste
derived from reprocessing of uranium and plutonium,
surplus plutonium, and other nuclear-weapons
materials. (Collectively, these radioactive
materials are known as high-level waste [HLW]
and are to be distinguished from the low-level radioactive
waste to be stored at the recently opened
Waste Isolation Pilot Plant in southeastern New
Mexico.) Tens of thousands of metric tons of HLW
is presently stored at more than a hundred sites in
40 States (fig. 1). The fundamental rationale for a
geologic repository for radioactive materials is to
securely isolate them from the environment and
its occupants to the greatest extent possible.