Declassification of the Amount of Weapon-Grade Plutonium Involved in
Fires at the Rocky Flats Plant, near Denver, Colorado, in 1957 and 1969
U.S. Department of Energy, Office of the Press Secretary, Washington, DC
Declassification of the Amount of Weapon-Grade Plutonium Involved in Fires
at the Rocky
Flats Plant, near Denver, Colorado, in 1957 and 1969
Who Are the Key Stakeholders?
Questions and Answers
The Department of Energy has declassified the amount of weapon-grade
plutonium involved in fires at the Rocky Flats Plant near Denver,
Colorado, in 1957 and 1969.
- Documents on the fires at the Rocky Flats Plant in 1957 and 1969
were previously released with classified information deleted. A report
on the 1957 fire was made public at Secretary O'Leary's December 7,
1993, press conference. A report on the 1969 fire was placed in the
reading room at the Rocky Flats Plant. This action declassifies the
amount of plutonium involved in the two fires and will allow the
documents to be released with minor deletions.
- The "book inventory" is the quantity of material present at a
given time as reflected by accounting records. The "physical inventory"
is the quantity determined to be on hand by first physically
ascertaining its presence and then using techniques that include
measuring, sampling, weighing, and analysis to determine its quantity.
Department of Energy Order 5633.3A defines the "inventory difference" as
the "book inventory" minus the "physical inventory."
- Based on an October 7, 1957, fire report, the total book inventory
of weapon-grade plutonium located in the area of the September 11, 1957,
fire in room 180, building 71 (Chemical Reprocessing and Fabrication
building) was 42.3 kilograms. There had been 14.3 kilograms in material
transferred out but not yet recorded in the accountability system and in
material whose exact amount and location was not known. Therefore, the
total book inventory in room 180 at the time of the fire was, as
accurately as possible, 28.0 kilograms. A study of inventory
differences dated January 6, 1964, looked at the inventory in building
71 at the time of the fire and the amount removed, recovered, and in
measured discards and concluded that the amount of inventory difference
represented a decrease in "book inventory" of 6.0 kilograms as a result of the
- The total "book inventory" of the weapon-grade plutonium involved
in the May 11, 1969, fire in buildings 776 and 777 (Plutonium
Fabrication and Assembly buildings) was 3557 kilograms. The measured
amount, "physical inventory," of plutonium recovered from material
removed from buildings 776 and 777 after the fire was 3651 kilograms.
The measured amount of plutonium in the debris generated as a result of
the fire and sent to waste was 10 kilograms. Thus, an inventory
difference of 104 kilograms more material was removed from the fire than
the book inventory indicated.
- The Rocky Flats Plant has had two major fires in which plutonium
may have been released outside of the affected buildings.
- "Holdup" is material that has adhered to gloveboxes, ducts, etc.,
over the years. While the majority of holdup in the complex is booked
based upon measurements or engineering estimates, the uncertainty of
these values is high. Verification of these values or the establishment
of more accurate values cannot be achieved until large- scale
dismantlement or recovery.
- Plutonium inventory in the buildings involved in the fires at the
Rocky Flats Plant was in different forms, including metals, compounds,
holdup, and scrap. After the fire, plutonium was measured by "physical
inventory." Most was recovered, including that in holdup; this explains
how it was possible to recover more plutonium than was in the "book
- Department of Energy sites perform frequent radiological surveys
to ensure that materials do not leave the site.
- The Department of Energy intends that the independent studies
conducted by the State of Colorado and the Centers for Disease Control
and Prevention should have the most accurate and factual information to
estimate offsite radiation and chemical from the Rocky Flats Plant that
resulted from the fires and to evaluate potential health effects on
citizens and the facility workforce.
- The quantity listed here is based on the evaluation of
the records available. The quantity may be updated or revised in the future
re-evaluation of the methodology used originally.
- As part of the Secretary of Energy's Openness Initiative, the
Department of Energy is declassifying information regarding the amounts
of weapon-grade plutonium involved in the 1957 and 1969 fires at the
Rocky Flats Plant. As a result of this declassification, the American
public will have information that is important to the current debate
over proper management and ultimate disposition of plutonium. This
declassification should encourage other nations to release similar
- This newly released information will permit the State of Colorado,
the Center for Disease Control and Prevention, and others to access the
necessary data for their study of the potential environmental and health
effects resulting from these fires.
- This information is useful in other worker and community health
studies and related activities.
- Regulators. The Rocky Flats program unit of the Colorado
Department of Health, the Director of the Colorado Department of Health,
and the Defense Nuclear Facilities Safety Board.
- The Public. Present and former employees and the local citizens
who are following dose reconstruction, environmental, safety and health,
and restoration issues at the Rocky Flats Plant.
- Public Interest Organizations. Stakeholders include
environmental, safety and health groups, historians, archivists,
researchers, scientists and industrial workers, as well as State and
Federal personnel. With this declassification, those interested in
oversight of plutonium related activities will have additional
information regarding the amount of weapon-grade plutonium involved in
fires at the Rocky Flats Plant near Denver, Colorado, in 1957 and 1959.
Public interest organizations which have expressed such an interest
include (but are not limited to): American Friends Service Committee;
Citizens Advisory Board; Colorado Council on Rocky Flats; Energy
Foundation; Environmental Information Network; Friends of the Earth;
Greenpeace; League of Women Voters; Military Production Network;
National Security Archive; Natural Resources Defense Council; Physicians
for Social Responsibility; Plutonium Challenge; Rocky Flats Cleanup
Commission; Rocky Flats Local Impact Initiative; Rocky Mountain Peace
Center; Sierra Club; and Western States Legal Foundation.
U.S. Department of Energy
Office of Public Affairs
Contact: Sam Grizzle
U.S. Department of Energy, Office of the Press Secretary, Washington, DC
Q. What is the health impact of plutonium released offsite and how much
was released from the plutonium fires at the Rocky Flats Plant.
A. Two major fires occurred in 1957 and 1969 at the Rocky Flats Plant.
A toxicologic review and dose reconstruction project, conducted by the
Colorado State Health Department, have quantified the major chemical and
radioactive materials released to the environment from Rocky Flats
during its years of operation. Although data and information on the
accidental releases are very limited, phase I of this study estimated
that between 0.002 and 2.4 curies of fine plutonium particles were
released from the 1957 fire and between 0.0001 and 0.056 curies were
released from the 1969 fire. The estimate of plutonium released from
the 903 Pad, where drums containing solvents contaminated with
plutonium, was 25 curies. As all of these materials did not travel
offsite or find their way into human exposure pathways, the highest
predicted radiation doses to offsite residents were small. For example,
the highest offsite dose resulting from the 1957 fire was estimated to
be 50 mrem and the highest dose from the 903 Pad releases to be 100
Phase I also estimated that a person offsite could have accumulated from
10-35 milligrams of carbon tetrachloride from 903 Pad, which is also a
potential carcinogenic hazard. The second phase of the study will
reevaluate historical records and monitoring data to help fill
informational gaps and reduce uncertainties in the phase I study. It is
currently underway and will be completed in 1996. Reference: "Project
Task 5 Report Estimating Historical Emissions from Rocky Flats," March
1994, Prepared by ChemRisk, Alameda, California.
Q. Can you explain how Rocky Flats could have recovered more plutonium
from the 1969 fire than was on the inventory books?
A. The "book inventory" does not contain the quantity in holdup since
there was no way to measure any holdups at that time. After the 1969
fire, there was a large-scale cleanup of the area which resulted in an
increase in the plutonium inventory. For example, plutonium powder was
recovered from the gloveboxes which increased the inventory during the
decontamination of the equipment. Holdup in the buildings was recovered
and a net gain in plutonium resulted. Incidentally, we expect to
recover additional holdup when the plant is fully decommissioned.
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