The total plutonium removed from the DOE/DoD inventory for the period 1944 to September 1994 was 12.0 metric tons. Of the 12.0 MT removed 3.4 MT were Expended in Wartime and Nuclear Tests, 2.8 MT were Inventory Differences, 3.4 MT were Waste (Normal Operating Losses), 1.2 MT were consumed by Fission and Transmutation, 0.4 MT was Decay and Other Removals, 0.1 MT was transferred to U.S. Civilian Industry, and 0.7 MT was transferred to Foreign Countries.
As stated earlier, the removals detailed in this report do not include plutonium sent to foreign governments under Military Agreements for Cooperation per Section 91C of the Atomic Energy Act of 1954, and DoD losses. These transactions remain classified for national security reasons.
Figure 9 shows a comparison of the quantities of plutonium removed from inventory for the various removal categories that are used in this report.
A total of 3.4 metric tons of plutonium was expended in all U.S. nuclear weapons tests, wartime detonations, and peaceful nuclear explosions. Most of this plutonium was associated with weapons-related research and development. The first test of a nuclear weapon was in the atmosphere on July 16, 1945, in a remote part of New Mexico on what was then the Alamogordo Bombing Range, now called White Sands Missile Range.
Between June 1946 and November 1962, the U.S. conducted atmospheric and underwater tests in the Marshall Islands, Christmas Island, Johnston Atoll in the Pacific Ocean, and over the South Atlantic Ocean. In addition, atmospheric and underground nuclear tests were conducted in Nevada, Colorado, New Mexico, Mississippi, and on Amchitka, one of the Aleutian Islands off the coast of Alaska.
Several of these tests were for the Plowshare Program to develop industrial and scientific applications for nuclear explosives. This program was based on the premise that the tremendous and relatively inexpensive energy available from nuclear explosives could be useful for a variety of peaceful purposes.
On October 31, 1958, President Eisenhower announced a unilateral U.S. moratorium on nuclear weapons tests with the understanding that the Soviet Union would likewise refrain from conducting nuclear tests. The Soviet Union resumed testing in September 1961 with a series of the largest tests ever conducted and, on September 30, 1961, the U.S. resumed nuclear testing at the Nevada Test Site.
The Hatfield-Exon-Mitchell Amendment to the FY 1993 Energy and Water Appropriation Bill (Public Law 102-377) mandated a 10 month moratorium on U.S. nuclear testing and restricted the purposes and numbers of any tests to be conducted before a Comprehensive Test Ban Treaty (CTBT) is concluded. The Hatfield Amendment mandated that only five tests could be conducted per year, with a maximum over a four year period being 15 tests. Further, it stipulated that these tests could only be conducted for the purposes of ensuring the safety of warheads which were installed with modern safety features, or to test the reliability of U.S. nuclear weapons.
President Clinton has extended this moratorium on three occasions, most recently in January of 1995 when he extended the moratorium until a CTBT enters into force (on the assumption that a CTBT is concluded by September 30, 1996). The United States’ goal is to conclude negotiations on a CTBT as soon as possible, so that the treaty can be open for signature at the 51st United Nations General Assembly in the fall of 1996.
As shown in Figure 10, the U.S. conducted 1,030 nuclear tests. The total does not include the two nuclear weapons detonated over Japan in World War II, which are not considered tests.
Information on nuclear tests is available in the DOE report, United States Nuclear Tests, July 1945 through December 1992, DOE/NV-209 (Revision 14), December 1994.
Inventory difference is the difference between the quantity of nuclear material held according to the accounting books and the quantity measured by a physical inventory. The cumulative plutonium inventory difference for the 50-year period from 1944 to 1994 is 2.8 metric tons.
Before 1978 inventory differences were identified as "material unaccounted for" (MUF). MUF was the more frequently used term in early days of nuclear materials accounting. MUF has at various times included the fractional amounts of nuclear materials lost in day to day operations and accumulated and accounted for as normal operating losses, accidental losses, and materials removed from a facility for quality control and safeguards analysis. Most historical data have been normalized over the past decade to the current practice of excluding these losses from the inventory difference calculation. Therefore, today's inventory difference values do not necessarily represent "losses" of nuclear material.
Inventory differences are not explained as losses but are explained as follows: (1) high measurement uncertainty of plant holdup [note 22]; (2) measurement uncertainties because of the wide variations of material matrix; (3) measurement uncertainties due to statistical variations in the measurement; (4) lack of measurement technology to accurately measure material; (5) measurement uncertainties associated with waste due to material concentration and matrix factors; (6) unmeasured material associated with accidental spills; and (7) recording, reporting and rounding errors
Since it is not prudent to discount the fact that a small inventory difference could possibly be due to theft, both DOE and contractors operating DOE facilities have always carefully investigated, analyzed and resolved every inventory difference to assure that a theft or diversion has not occurred.
In addition to detecting losses, analysis of inventory differences provides valuable information on the effectiveness of the safeguards system's physical protection and material control measures, as well as a check on the process controls and material management procedures. DOE and the contractors operating DOE facilities analyze and explain all significant inventory differences (i.e., outside strict statistical control limits) as well as missing items. If necessary, an operation may be shut down until any inventory differences are resolved.
As part of the inventory difference evaluation, other security events are reviewed to ensure that inventory differences are not linked to breaches of physical security or insider acts. If there is no evidence of security breaches, then inventory differences are less likely to be caused by malevolent acts, since integrated security and safeguards work to provide defense-in-depth.
Data on inventory differences are presented in Figure 11 as a single, cumulative number for each of the major DOE sites from the beginning of operations through September 30, 1994. The 2,735.8 kg of plutonium identified at the June 27, 1994 Openness Press Conference, has been updated through September 1994. In addition, a single cumulative number for the inventory differences at other Department sites and commercial licensees which processed DOE plutonium is provided.
For a thorough discussion of inventory differences by fiscal year and DOE site, please refer to the Report on Strategic Special Nuclear Material Inventory Differences, ERDA 77-68, August 1977 and the periodic updates published through 1992.
By reviewing the above referenced documents it can be seen that 68% of the inventory difference occurred during the period prior to the late 1960's, when predictive reactor codes (i.e., conversion ratios) and materials measurement technologies were less accurate than today. It should also be noted that contractors operating the highest through-put sites also had the greatest inventory differences, suggesting that inventory differences are largely due to measurement and operations-related activities, and other non-security related events.
Normal operating losses (NOL) occur when quantities of plutonium, determined by measurement or estimated on the basis of measurement, are intentionally removed from inventory as waste because they are technically or economically unrecoverable. As shown in Figure 12, a total of 3.4 metric tons of plutonium was removed from the inventory as waste from normal operating losses.
Some examples of waste are discharges to cribs, tanks, settling ponds, or to waste disposal facilities generically referred to as "burial sites." Major DOE burial sites are located at the Idaho National Engineering Laboratory Site, the Hanford Site, the Savannah River Site, and Los Alamos National Laboratory. Examples of plutonium bearing items sent to burial sites include discarded piping, spent ion exchange equipment, processing resins, and contaminated laundry and shoe covers.
The sites with the largest amount of plutonium in normal operating losses are Rocky Flats (1.0 MT), the Hanford Site (1.1 MT), Los Alamos National Laboratory (approximately 0.6 MT), and the Savannah River Site (0.5 MT). These are shown in Table 9.
The remaining 0.2 MT of plutonium in NOL occurred at the Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Argonne National Laboratory-West (Idaho), Argonne National Laboratory-East (Illinois), and U.S. companies that processed plutonium for the DOE.
As stated earlier, this report refers to "normal operating losses" as "waste." However, normal operating losses are actually just one estimation of the amount of plutonium managed as waste. The NMMSS data base on which this report is based differentiates between normal operating losses and waste. While all normal operating losses are considered waste, the reverse is not true. The total amount of plutonium in "waste" is 3.9 MT of which 3.4 MT is accounted for as NOL. In addition, these waste estimates within NMMSS may not agree with amount of plutonium in waste reported in other Departmental sources, such as the Integrated Database which collects information on waste volumes including plutonium in waste. A more complete explanation for these differences is found in Appendix B.
Fission and transmutation removals account for plutonium consumed by nuclear irradiation as a result of exposure in a reactor. Fission and transmutation can be divided into two distinct categories: isotope production and burn-up. A total of 1.2 metric tons plutonium was removed from the inventory by these processes. Annual fiscal year removals are shown in Figure 13 and Table 10.
Plutonium was transformed to other materials as part of the Department's isotope development program. The objective of the program was to develop, produce and demonstrate applications of radioisotopes for industry, medicine and nuclear and radiation research. The isotope development program aimed to develop technology for the production, separation, purification, and encapsulation of isotopes utilizing resources of both the Department and industry.
This category was used to report plutonium that was transformed to other materials such as Plutonium-242, Plutonium-244, Americium, Curium, and Californium-252.
Californium-252 was produced in the Savannah River Site reactors and in the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor in the late 1960's. Californium-252 is an excellent spontaneous fission neutron source for oil well logging, industrial radiography, reactor start-up, nuclear physics research, and medical applications.
Plutonium-242 was produced in the SRS reactors in the late 1960s. It is useful as target material for production of Plutonium-244, and nuclear physics research and applications in weapons programs. Plutonium-244 was produced in the SRS reactors in the late 1960s for use as a standard reference material for nuclear analysis and in nuclear fuel tagging.
The burn-up category accounts for plutonium that was consumed in the operation of experimental fast neutron and breeder reactors. The fuel for these reactors was fabricated from plutonium provided by the Government. Some of the reactors that used plutonium fuels included Southwest Experimental Fast Oxide Reactor (SEFOR) in Arkansas, the Fast Flux Test Facility (FFTF) in Washington State, and the Experimental Breeder Reactor 2 (EBR 2) in Idaho.
This category accounts for all plutonium lost through radioactive decay, accidental losses, and approved write-offs. A total of 0.4 metric tons of plutonium was removed from the material balance using this category, almost all through decay.
Decay losses are primarily due to the decay of Plutonium-241, which has a half-life of 14.35 years and decays to Americium-241 in aged plutonium. Other isotopes of plutonium have also decayed over time as well, primarily to uranium. A total of 0.4 MT plutonium was removed from the material balance using this category.
Accidental losses occur infrequently and usually involve small quantities of material. A total of 4.5 kg of plutonium was removed from the material balance using this category. Quantities of plutonium removed as accidental losses are shown in Table 11.
Accidental losses are similar to Normal Operating Losses in that these removals generally involve discards to cribs, tanks, settling ponds, or waste disposal facilities referred to as "burial sites." While a Normal Operating Loss is an intentional or planned removal from the inventory, an accidental loss is an unplanned removal.
An example of an accidental loss would be material spilled in a processing cell. The material is collected in a sump, pumped to a holding tank, and measured prior to being transferred to a waste tank.
A total of 4 kg plutonium was removed from the plutonium inventory under this category, and are shown in Table 12.
Approved write-offs occur when plutonium is written off the inventory because accountability is no longer deemed necessary for that material. An example of this would be small amounts of plutonium fixed on concrete in operating cells of process facilities. The plutonium is not easily removed and will eventually end up as a discard to a waste management site. If the facility is later decontaminated and the plutonium is recovered, the previously estimated approved write-off would be debited from the accounting inventory and the actual quantity would be reentered into the inventory. Approved write-offs occur infrequently and require the approval of the cognizant DOE field organization.
This category consists of plutonium that has been sold or permanently transferred by the Department to U.S. civilian industry. A total of 0.1 metric ton of plutonium is included in the material balance using this category.
Mandatory government ownership of special nuclear material in the U.S. was ended on August 26, 1964 with the Private Ownership of Special Nuclear Materials Act. As a result of this law, plutonium produced in some AEC-owned and public utility-operated prototype reactors was transferred from the Government to the operators of the utility. For example, in 1974 the AEC transferred the ownership of 42 kg of plutonium to the Dairyland Power Cooperative. The Dairyland Power Cooperative operated the La Crosse boiling water reactor, an AEC owned reactor located on the Mississippi River near Genoa, Wisconsin.
The balance of the plutonium was sold or donated to universities, hospitals, and other industry, primarily in the form of sealed sources.
Removals to foreign countries consists of plutonium transferred under Agreements for Cooperation. A total of 0.7 metric ton of fuel grade plutonium was removed from the material balance using this category.
The Department's international activities are authorized by the Atomic Energy Act of 1954, as amended and the Nuclear Nonproliferation Act of 1978. In addition to authorizing foreign exchanges and sales of nuclear material, these acts require that nuclear material exported under that authority be subject to safeguards and physical protection measures.
Section 3.4 of this report discusses in detail how these requirements are satisfied. Generally, U.S.-origin nuclear material is subject to international safeguards applied by the International Atomic Energy Agency (IAEA) and the determination of the adequacy of physical protection measures of the U.S.-origin material is the responsibility of the U.S. Government. The Department of Energy, in cooperation with the Departments of State and Defense, and the Nuclear Regulatory Commission conducts a program of bilateral reviews of physical protection for U.S.-origin nuclear material at foreign facilities.
Under the Atoms for Peace Program, started during the Eisenhower Administration, the Department exchanged information on peaceful uses of nuclear materials with other nations, including the sale of nuclear fuels for power and research reactors.
Agreements for Cooperation in the civil uses of atomic energy provided the framework for these activities. Almost forty agreements covering foreign exchanges and sales were in effect. An important part of each agreement was the establishment of procedures to assure that the materials or equipment supplied was not diverted from peaceful to military uses.
A total of 0.7 metric ton of plutonium was shipped to foreign countries, primarily to countries participating in the European Atomic Energy Community (Euratom), Japan, and the United Kingdom. Euratom was established in 1957 and originally consisted of six countries (Belgium, France, Italy, Luxembourg, the Netherlands, and Germany). The U.S. also participated in joint projects with the European Nuclear Energy Agency and with individual countries under bilateral agreements. Cooperative research was being conducted in many areas such as fast breeder reactors, reprocessing of nuclear fuels, lowering fuel cycle costs in power reactors, food irradiation, and dual purpose nuclear power-desalting plants. However, the majority of the plutonium exported to foreign countries was for use in breeder reactor research.
Five of the six Euratom countries received approximately 575 kilograms of plutonium from the U.S. Government. This plutonium was shipped in accordance with bilateral agreements with the individual countries or under the United States-Euratom Agreement for Cooperation.
From 1962 to 1991, approximately 114 kg of plutonium were exported to Japan. The largest shipments occurred in 1969 and 1970 when 104 kg of plutonium in the form of reactor fuel elements and oxide were shipped to Japan, primarily to the Fast Critical Assembly at Tokai-Mura.
From 1974 to 1988, approximately 34 kg of plutonium were sent to the United Kingdom. The largest shipments occurred in 1980 and 1981 when 32 kg of plutonium in the form of reactor fuel elements were shipped to the Sellafield fuel fabrication facility.
Austria, Canada, Israel, Switzerland, and Sweden received about 24 kg of plutonium under various Agreements for Cooperation. Most of this plutonium was in the form of fuel elements and oxide.
Twenty-seven additional countries and the IAEA received the remaining 2 to 3 kilograms of plutonium exported under Agreements for Cooperation. Most of this plutonium was in the form of sources. Sources are used for calibration of radiation measuring and monitoring instruments and in nuclear research and development activities.
Quantities of plutonium exported are shown by country in Table 13 and by year in Table 14.