The Manhattan Project Resources

U.S. Department of Energy

Office of Environment, Health, Safety and Security

Office of History and Heritage Resources

Plutonium: The First 50 Years


Over the 50 year history of the U.S. plutonium programs, there have been many different facilities involved in the production, processing, and utilization of U.S. plutonium. DOE-owned plants and equipment include reactors for the production of plutonium, isotopes and other reactor products; facilities for the fabrication and testing of weapons; reactors for testing materials and equipment components; reactor prototypes; and research laboratories.

Figure 2 is a map showing the location of the Department's plutonium facilities mentioned in this report.


Significant amounts of information concerning plutonium have been declassified. The following are examples of information declassified since 1993 concerning U.S. plutonium inventory data.

  • The total and annual quantities of plutonium produced at the Hanford Site.
  • The total and annual quantities of weapon grade plutonium produced at the Savannah River Site.
  • Plutonium produced at Government-owned nonproduction reactors.
  • The approximate total quantity of plutonium at Savannah River after August 1988.
  • The United States total production of weapon grade plutonium.
  • Current total plutonium inventories at DOE sites, excluding the Pantex Plant near Amarillo, Texas.
  • Current and historical inventory differences for plutonium in the DOE complex.
  • Total quantity of plutonium expended in all U.S. nuclear tests including wartime detonations, nuclear weapons tests, and peaceful nuclear explosions.
  • Quantity of weapon grade plutonium involved in fires at the Rocky Flats Plant in 1957 and 1969.

For greater specifics on declassified information, refer to Drawing Back the Curtain of Secrecy, Restricted Data Declassification Policy, 1946 to the Present, RDD-1, U.S. Department of Energy, Office of Declassification, June 1, 1994.


The following is a summary of newly declassified information being released by this report.

  • Total DOE/DoD plutonium inventory.
  • Combined DOE/DoD plutonium inventory at the Pantex Site, near Amarillo, Texas, and in the U.S. nuclear weapons stockpile.
  • Total plutonium received by barter from the United Kingdom (U.K.) under the 1958 U.S. and U.K. Mutual Defense Agreement.
  • Total quantities of tritium and enriched uranium transferred to the United Kingdom by barter under Mutual Defense Agreements.

In addition, this report also summarizes 50 years of unclassified information including the following:

  • Total plutonium received from other countries under bilateral agreements for international cooperation in the peaceful uses of atomic energy.
  • Total plutonium transferred or sold to other countries under bilateral agreements for international cooperation in the peaceful uses of atomic energy.
  • Total plutonium received from U.S. civilian industry including separated plutonium from the Nuclear Fuels Services facility located near West Valley, New York.
  • Total plutonium transferred to U.S. industry.
  • Total plutonium in waste as identified in NMMSS.


Plutonium is a silvery, metallic radioactive element with an atomic number of 94. Although found naturally in trace quantities in uranium ores, plutonium is abundantly produced in reactors by neutron bombardment of uranium. Plutonium has 15 isotopes [note 6] ranging from Pu-232 to Pu-246 and half-lives [note 7] from 20 minutes to 76 million years. The NMMSS tracks plutonium in three distinct categories, Plutonium, Plutonium-238, and Plutonium-242.

  • Plutonium, sometimes referred to as Plutonium-239, is the most common plutonium isotope and is capable of sustaining a nuclear chain reaction and is used in nuclear weapons and for nuclear power production.
  • Plutonium-238 [note 8] is used in general purpose heat sources and radio isotope thermoelectric generators to produce electricity in spacecraft and is not addressed in this report.
  • Plutonium-242 [note 9] is used as target material for the production of other nuclear materials, and in nuclear physics research and is not addressed in this report.

Plutonium is identified as either weapon grade, fuel grade, or power reactor grade based on the percentage of Plutonium-240 that is contained in the plutonium. Weapon grade plutonium contains less than 7 percent Pu-240. Fuel grade plutonium contains from 7 percent to less than 19 percent Pu-240, and power reactor grade contains from 19 percent and greater Pu-240.

The U.S. plutonium inventory is composed of 85.0 MT of weapon grade, 13.2 MT of fuel grade, and 1.3 MT of reactor grade (Figure 3). Of the 85.0 MT of weapon grade plutonium, 38.2 MT have been declared excess to national security needs. The composition and location of this 38.2 MT can be found in Appendix A.

Figure 4 shows the location of the DOE/DoD 99.5 MT of plutonium as of September 30, 1994. In addition to the eight sites identified in Figure 4, DOE plutonium is also located at other DOE sites, primarily at the West Valley Demonstration Project located near Buffalo, New York. Small quantities are also located in foreign countries, and at NRC licensees. Plutonium in waste (e.g., in cribs, tanks, settling ponds, and waste disposal facilities) is not considered part of the DOE/DoD inventory, and is therefore not included in the 99.5 MT.

Most of the plutonium in waste -- technically "normal operating losses" -- has been removed from DOE/DoD inventory that requires safeguards and security. While this report refers to normal operating losses as waste, not all plutonium in waste is necessarily derived from normal operating losses. Other plutonium in DOE waste can be accounted for as accidental losses, approved write-offs, and inventory differences. In addition, some plutonium in waste has been received from sources outside of DOE. Further discussion of plutonium in waste can be found in Appendix B.


The data used to prepare this section were obtained primarily from the Department's nuclear material control and accountability system. The plutonium acquisition and removal categories used in this report contain the following elements:

  • Plutonium acquisitions are divided into four distinct categories: plutonium produced in government production reactors; plutonium produced in government nonproduction reactors; plutonium acquired from U.S. civilian industry; and plutonium acquired from foreign countries.
  • Plutonium removals are divided into seven categories: plutonium expended in wartime and nuclear tests; plutonium inventory differences; plutonium waste; plutonium expended in fission and transmutation; plutonium lost to decay and other removals; plutonium transferred to U.S. civilian industry; and plutonium transferred to foreign countries.

As shown in Table 1, the U.S. Government produced and acquired from 1944 to September 1994 a total of 111.4 metric tons of plutonium. During the same period of time, 12.0 MT of plutonium was removed resulting in an actual ending inventory of 99.5 MT [note 10].

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