Introduction

Initial nuclear power research by the United States focussed on weapons production for World War II. Shortly after the war, however, the U.S. Government encouraged civilian applications for nuclear power, particularly for commercial electricity.

The development of nuclear power, coupled with U.S. Government encouragement, caused the demand for private industry's components and services to grow, such that by the mid-1960s Federal assistance was no longer necessary to build a nuclear reactor.' As of 1983, nearly 80 commercial nuclear reactors generated electricity in the United States. Figure 1-1 illustrates the status of U.S. nuclear power reactors as of January 1983. Government reactors on Federal sites continue to produce plutonium and tritium for military applications. The United States has more commercial reactors than do other nations, but because of our country's size, these reactors still account for only a relatively small amount of our power output. France, for example, has 32 reactors producing over 40 percent of its national power.*

Nuclear reactor operations result in radioactive waste, which has accumulated in large quantities. Although the principal sources of waste are generated from fueling nuclear reactors, much radioactive material comes from educational, medical, and research institutions as well as from private and government laboratories. Currently, more than 20,000 facilities in the United States are licensed to use radioactive materials as part of their activities. These facilities generate radioactive wastes that exist in various chemical forms and may be solid, liquid, or gaseous. The Federal Government has classified these radioactive materials and placed them into the following categories.

Spent fuel is irradiated fuel discharged from nuclear reactors. In commercial reactors, this material typically contains about 96 percent unused uranium, 1 percent plutonium, and 3 percent other fission products categorized as high-level waste. Of the unused uranium, 99 percent is uranium-238, and 1 percent is fissile uranium-235.9

For continued operation, nuclear power plants require periodic replacement of uranium fuel with fresh fuel, which depends on the amount of reactor operating

time; about one-third of the reactor core fuel is replaced every 12 to 18 months.10 A standard nuclear power reactor discharges about 30 metric tons of spent fuel rods each year."1

Most U.S. spent fuel is stored in pools of circulating water at commercial nuclear power reactor sites. Special government fuels, used for defense and research purposes and not routinely reprocessed, are stored at the Savannah River Plant and the Idaho Chemical Processing Plant."2

High-level waste (HLW) is a term with several different meanings. In the United States, HLW is sometimes defined as only the wastes generated in reprocessing spent fuel." With this definition, most HLW in the United States is the residue from the reprocessing of irradiated fuel in the weapons program. Unprocessed spent fuel, however, is often included in the definition of HLWIS, which thus creates some ambiguity in common usage and meaning. The International Atomic Energy Agency (IAEA) definition of HLW includes all waste, irrespective of source, in which concentrations of radionuclides are high enough to be considered unsuitable for disposal at sea. IAEA currently uses the following limits of activity to define HLW:16

Alpha emitters ............ 1 curie or more/metric ton
Beta or

(For more information on the IAEA definition, see Table III-1 in Chapter III of this report.)

Transuranic wastes (TRU), as defined by U.S. Department of Energy (DOE) Order 5820.2, contain at the end of their institutional control period 100 nanocuries (1 nanocurie = 109 curies) or more per gram of alpha-emitting radionuclides with an atomic number greater than 92 (uranium) and long half-lives (greater than 20 years). TRU arises primarily from the reprocessing of fuel and from the fabrication of plutonium weapons and plutonium-bearing reactor fuel."7

Low-level waste (LLW) is any radioactive waste not classified as mill tailings, HLW, TRU, spent fuel, or by-product material as defined in Public Law 96-573, the Low-Level Radioactive Waste Policy Act of 1980, and Public Law 97-425, the Nuclear Waste Policy Act

of 1982. LLW contains low, but potentially hazardous, amounts of radionuclides, and may have a radiation level high enough to necessitate shielding in handling or transport.18

Active uranium mill tailings are the earthen residue remaining after uranium ore extraction. Although tailings occur in very large amounts, they contain low concentrations of natural radionuclides, such as radon222 and radium-226. The tailings derive from the conventional mining and milling methods to obtain uranium. Of the 26 licensed mills in the United States, 16 are currently active.19

Intermediate waste is not a category officially used by the United States. This term is, however, used by certain European countries to manage nuclear waste

forms that do not require the rigid constraints of HLW but cannot be handled as LLW.20

Airborne waste pertains to krypton-85, iodine-129, carbon-14, tritium, and airborne radioactive particulates that require special treatment. According to DOE, these are considered effluents if released, but once trapped and retained are classified as LLW under current guidelines.21

The Nuclear Fuel Cycle

Most radioactive waste results from the various stages of the nuclear fuel cycle, which consists of all the steps needed for a nuclear power system, plus reprocessing