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Declassification of Today's and Historical Inventory Differences for Weapon-Grade Plutonium and Highly Enriched Uranium at the Rocky Flats Plant, near Denver, Colorado

U.S. Department of Energy, Office of the Press Secretary, Washington, DC 20585


Declassification of Today's and Historical Inventory Differences for Weapon-Grade Plutonium and Highly Enriched Uranium at the Rocky Flats Plant, near Denver, Colorado

Table of Contents

Specifically
Background
Benefits
Who Are the Key Stakeholders?
Contact
Attachments
Questions and Answers

The Department of Energy has declassified today's and historical inventory differences for weapon-grade plutonium and highly enriched uranium at the Rocky Flats Plant near Denver, Colorado. Highly enriched uranium is defined as uranium having an enrichment above 20 percent of the fissionable isotope uranium-235. Weapon-grade plutonium contains less than 7 percent of the isotope plutonium-240.

Specifically

Background

Benefits

Who Are the Key Stakeholders?

Contact

U.S. Department of Energy
Office of Public Affairs
Contact: Sam Grizzle
(202) 586-5806


Attachments

Historical Plutonium Inventory Difference at the Rocky Flats Plant

Historical Highly Enriched Uranium Inventory Difference at the Rocky Flats Plant

Today's Total Plutonium Inventory Difference

Today's Total Highly Enriched Uranium Inventory Difference


U.S. Department of Energy, Office of the Press Secretary, Washington, DC 20585


QUESTIONS AND ANSWERS

Q. Is the plutonium and highly enriched uranium missing? If it is not missing, can you account for it?

A. The plutonium and highly enriched uranium related to inventory differences are not "missing." Inventory differences result from reconciling "book inventories" and physical inventories, after adjustments for transactions, removals, decays, corrections, transmutation, and production. The size of the inventory differences results from remeasurements, high measurement uncertainty of holdup of material resulting from processing, and data rounding and input errors. The unavailability of highly precise and accurate measurement capabilities and less rigorous accounting practices prior to the mid-1970's, all of which have largely been overcome today, have significantly contributed to the differences observed during this period.

Q. If you do not know where the material is, isn't it possible that holdup material could undergo a nuclear reaction or explosion?

A. If the material were in any one location in a sufficiently large quantity, it would be easily detected by routine radiation surveys. We monitor our facilities for radiation for just this purpose.

Q. How can you assure us that the material did not go into the environment?

A. Onsite reviews indicate that the material did not go into the environment. The contributions to inventory differences are many. The total amount for any time period is the sum of many smaller differences. Each one arises for one or more of the reasons enumerated. Each inventory difference is investigated to assign its cause and to help assure that no loss, diversion, theft or environmental contamination occurred. Any substantial loss to the environment would be identified by routine radiological surveys.

Q. Why do you think that you will "find" a large quantity of this material when you decontaminate and decommission the plant?

A. From past experience with such actions both here and at other facilities, we find that a large part of the cumulative inventory difference is regained from such extensive cleanup actions. We cannot do such complete cleanup when a facility is in operation because it requires the dismantlement of the facility.

Q. How can you assure us that someone did not steal or divert the material?

A. Stringent security measures have made theft or diversion unlikely. Physical security will respond to design-basis threats based upon specific events and intelligence assessments. These threats include terrorists, nuclear weapon proliferants, and criminals. These threats, in addition to those related to malevolent insiders, have been drivers behind the type and level of safeguards and security measures in place at Departmental nuclear facilities today. These measures prevent, deter, detect, and respond to losses of nuclear material. Prevention measures include barriers and protective forces.

Deterrence and detection are achieved through a combination of personnel security, material access controls, materials accountability, and physical security. Response capabilities exist to interrupt or stop malevolent acts such as diversion/theft of nuclear materials that have negative consequences on national security. These safeguards and security measures give us high confidence that no plutonium and highly enriched uranium was stolen or diverted and that if these acts were attempted or had occurred, they would have been detected.

Q. Didn't inventory differences used to be called "material unaccounted for" or "MUF?"

A. Yes. However, the term "inventory difference" is more descriptive of the actual situation, namely differences between accounting records and inventory by physical identification and measurements. Each inventory difference accounting transaction is investigated and resolved per Department of Energy Orders. The term "MUF" does not accurately convey this process and procedure.


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