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A Closer Look

Nuclear Waste
here are two general categories of age at the plant sites. These rods are “hot”
Tnuclear wastes: (1) low-level wastes in the radioactive sense, producing about
and (2) high-level wastes. The low-level 100,000 curies per cubic foot. They are
wastes are produced by hospitals, universi- also hot in the thermal sense, continuing
ties, and other facilities. They are also pro- to generate heat for months after removal
duced by the normal operation of a nuclear from the reactor. The rods are cooled by
reactor. Radioactive isotopes sometimes heat exchangers connected to storage pools;
escape from fuel rods in the reactor and they could otherwise achieve an internal
in the spent fuel storage pools. These iso- temperature as high as 800°C for several
topes are removed from the water by ion decades. In the future, these spent fuel rods
exchange resins and from the air by filters. will be reprocessed or disposed of through
The used resins and filters will contain the terminal storage.
radioactive isotopes and will become low- Agencies of the U.S. government have
level wastes. In addition, any contaminated also accumulated millions of gallons of
protective clothing, tools, and discarded high-level wastes from the manufacture
equipment become low-level wastes. of nuclear weapons and nuclear research
Low-level liquid wastes are evapo- programs. These liquid wastes are stored
rated, mixed with cement, then poured into in million-gallon stainless steel contain- BOX FIGURE 13.3 This is a standard
55-gal steel drums. Solid wastes are com- ers that are surrounded by concrete. The warning sign for a possible radioactive
pressed and placed in similar drums. The future of this large amount of high-level hazard. Such warning signs would have
drums are currently disposed of by burial in wastes may be evaporation to a solid form to be maintained around a nuclear waste
government-licensed facilities. In general, or mixture with a glass or ceramic matrix, depository for thousands of years.
low-level waste has an activity of less than which is melted and poured into stainless
1.0 curie per cubic foot. Contact with the steel containers. These containers would
low-level waste could expose a person to up be buried in solid granite rock in a stable would provide protection from exposure
to 20 millirems per hour of contact. geologic depository. Such high-level wastes by explosives, meteorite impact, or ero-
High-level wastes from nuclear power must be contained for thousands of years sion. One major concern about this plan
plants are spent nuclear fuel rods. At pres- as they undergo natural radioactive decay is that 100 generations later, people might
ent, most of the commercial nuclear power (Box Figure 13.3). Burial at a depth of 610 lose track of what is buried in the nuclear
plants have these rods in temporary stor- to 914 m (2,000 to 3,000 ft) in solid granite garbage dump.

fusion reaction requirements of (1) temperature, (2) density,
and (3) time (Figure 13.22):
1. Temperature. Nuclei contain protons and are positively
charged, so they experience the electromagnetic repulsion Alpha particle

of like charges. This force of repulsion can be overcome,
moving the nuclei close enough to fuse together, by giving Energy –12

the nuclei sufficient kinetic energy. The fusion reaction of (2.8 ✕ 10 J)
deuterium and tritium, which has the lowest temperature Deuterium Tritium
requirements of any fusion reaction known at the present nucleus nucleus
time, requires temperatures on the order of 100 million°C.
2. Density. There must be a suffi ciently dense concentration

14
3
of heavy hydrogen nuclei, on the order of 10 /cm , so
many reactions occur in a short time.

3. Time. The nuclei must be confined at the appropriate
density up to a second or longer at pressures of at least
10 atmospheres to permit a suffi cient number of Neutron
reactions to take place.
FIGURE 13.22 A fusion reaction between a tritium nucleus
The temperature, density, and time requirements of a fusion and a deuterium nucleus requires a certain temperature, density,
reaction are interrelated. A short time of confinement, for example, and time of containment to take place.
344 CHAPTER 13 Nuclear Reactions 13-22