Plutonium is a man-made, radioactive element that exists in different isotopes and physical forms. The different isotopes of plutonium have widely varying half-lives, ranging from 20 minutes to 76 million years. These isotopes are used to define the different grades of plutonium that are used in nuclear warheads and as fuel for nuclear reactors. Physically, plutonium exists in several forms—metal, which is relatively stable if packaged correctly, and other forms that are often unstable, such as oxides, solutions, residues, and scraps. During the production era, DOE recycled, purified, and converted the less stable forms of plutonium, which resulted from weapons production activities, into metal for use in nuclear warheads. Much of DOE’s excess plutonium was not in a suitable form or packaged for long-term storage when weapons production ceased. As a result, some packaging and related problems have developed over time. (See app. I.) From World War II to the end of the Cold War, DOE and its predecessor agencies conducted nuclear research, produced plutonium, and manufactured and tested nuclear weapons at sites throughout the United States. No plutonium has been produced for weapons since 1988. The 99.5 metric tons of plutonium that remain in the U.S. government’s inventory today is in the custody of the Department of Defense (DOD) and DOE. DOD has custody of the plutonium in warheads in the nuclear weapons stockpile, which are located at military bases around the world, and DOE manages the rest of the plutonium, which is located primarily at eight DOE sites: Argonne National Laboratory-West, Hanford Site, Idaho National Engineering and Environmental Laboratory (INEEL), Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Pantex Plant, Rocky Flats Environmental Technology Site, and Savannah River Site. (See fig. 1.) Although DOE no longer produces plutonium for weapons, some of the plutonium it produced in the past continues to present environmental, safety, and health hazards, as well as concerns about proliferation, and therefore requires careful management. The hazards and concerns associated with plutonium include the following: Plutonium is extremely toxic and can be fatal, especially when inhaled. Several kilograms of plutonium are sufficient to make a nuclear bomb. Although attempts are made to control access to nuclear materials, thefts have occurred in the former Soviet Union since the end of the Cold War, raising concerns about nuclear proliferation and international terrorism. Today, land, buildings, and equipment used in making nuclear weapons, remain contaminated and present environmental hazards. To address these hazards, DOE expects to spend nearly $229 billion over the next 75 years. Although DOE does not track cleanup costs specifically for plutonium, a major portion of these costs can likely be attributed to plutonium or related activities. Additional information on the dangers of plutonium is provided in appendix I. Even though the United States no longer manufactures new nuclear weapons, some plutonium is still used in nuclear weapons and for research, development, and testing programs. DOD establishes nuclear weapons requirements, and DOE subsequently determines how much plutonium is necessary to support these requirements. The Nuclear Weapons Council (NWC) coordinates nuclear program activities between DOD and DOE and submits documents containing weapons requirements to the National Security Council and the President for approval. The nation’s 99.5-metric-ton inventory of plutonium is divided into two categories—that which is allocated for national security (46.8 metric tons) and that which is designated as excess (52.7 metric tons). The national security plutonium is further allocated among several subcategories. Although DOE could justify most of these allocations, we found that it had no technical basis for the amounts of plutonium allocated for reliability replacement warheads and for the strategic reserve. In 1995, for the first time in the history of the U.S. nuclear weapons program, the United States declared that 38.2 metric tons of weapons-grade plutonium was no longer needed for national security and was, therefore, excess. (In addition, DOE designated 14.5 metric tons of non-weapons-grade plutonium as excess.) According to DOE, this declaration was an important step in implementing the Nonproliferation and Export Control Policy, which was issued by the President in September 1993. This policy calls for the United States to eliminate, where possible, the accumulation of plutonium stockpiles and prevent the proliferation of weapons of mass destruction. According to DOE officials, DOE reviewed its existing plutonium inventory records to determine how much of its weapons-grade plutonium was needed for national security. All weapons-grade plutonium that was in the custody of DOD in the active and inactive stockpile and some of the weapons-grade plutonium assigned to and managed by DOE’s Defense Programs organization was categorized as needed for national security. This plutonium is for use in nuclear weapons; the strategic reserve; mutual defense; and research, development, and testing programs. All other plutonium that was assigned to or managed by any other DOE organizations (as well as the plutonium remaining with Defense Programs that was not required for national security) was categorized as not needed for national security. Ultimately, DOE will dispose of this excess plutonium. On the basis of this inventory review, DOE decided that 46.8 metric tons of weapons-grade plutonium should be held for national security and that the remaining 52.7 metric tons of plutonium—including 38.2 metric tons of weapons-grade and 14.5 metric tons of non-weapons-grade—could be declared excess to national security needs. The categorization of the current U.S. plutonium inventory is shown in table 1. Significant changes in the amounts of plutonium dedicated to national security are unlikely in the near future. According to DOE officials, the United States has no plans to formally declare additional amounts of plutonium excess to national security needs. According to one DOE official, any future declarations would depend on international agreements or political decisions, such as (1) Russia’s ratification of the second Strategic Arms Reduction Treaty (START-II); (2) ratification of possible additional weapons reduction treaties, like START-III; or (3) a change in the role of nuclear weapons in the nation’s defense posture. However, even these events would not necessarily result in additional declarations of excess plutonium. Instead, according to a DOE official, decreases in the active stockpile may be offset by reclassifying some of the plutonium from the active stockpile to the inactive stockpile or the strategic reserve. Therefore, even if the number of active warheads decreases, the total amount of plutonium allocated for national security will likely remain at 46.8 metric tons. The national security plutonium is allocated among four categories, and the amounts in these categories are classified. According to DOE, the allocation for the first and second categories, warheads in the active and inactive nuclear weapons stockpile, are in weapons in the custody of DOD. The remainder of the national security plutonium, managed by DOE, is allocated to the strategic reserve and to mutual defense and research and development programs. Although DOE could justify the amounts of plutonium allocated to most of these categories, it could not provide a technical basis for the amounts allocated for reliability replacement warheads within the inactive stockpile and for the strategic reserve. Table 2 lists the allocations of national security plutonium and their principal uses and indicates whether the allocations have a technical basis. As table 2 indicates, DOE appeared to have a technical basis for most of the allocations of national security plutonium. DOE provided the following justifications for these allocations: The allocation for the active stockpile is determined through an annual process driven by DOD’s nuclear weapons requirements. DOD determines the types and numbers of weapons it wants to support national security needs, and DOE determines how much plutonium is needed for the required warheads and for their support. Augmentation warheads in the inactive stockpile are reserved to allow DOD and DOE to raise the active stockpile levels if necessary. Additional warheads in the inactive stockpile are held to replace warheads that are removed from the active stockpile and used for testing. The number of warheads needed as replacements is based on requirements of DOE’s Quality Assurance and Reliability Testing Program. The amount of plutonium held for mutual defense is based on signed agreements between the United States and its allies. The plutonium held for research and development is used by DOE’s laboratories and its amount is based on an established forecast and allotment system. While DOE appeared to have adequate justification for these allocations of national security plutonium, it could not justify the allocations of plutonium for reliability replacement warheads in the inactive stockpile or for the strategic reserve, which represent a significant portion of the national security plutonium: Neither DOE nor NWC officials could demonstrate a basis for the number of reliability replacement warheads being held to replace active stockpile warheads in case they develop reliability or safety problems. DOE and NWC could not demonstrate that an analysis of the failure rate for active warheads had been conducted or that a technical assessment had been done to determine the need for this level of backup support. According to DOE, the plutonium held in the strategic reserve is for rapidly building warheads to respond to unforeseen events (such as warhead failures) that are not already provided for in the inactive stockpile. However, neither DOE nor NWC officials could demonstrate that a technical analysis had been conducted to justify the amount of plutonium held for this purpose.