ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Rocky Flats Plant – Site 

Description

Document Number:

ORAUT-TKBS-0011-2 

Effective Date: 01/10/2004

Revision No.: 00 

Controlled Copy No.: ________

Page 1 of 58

Subject Experts: Susan Flack, Robert Meyer

Document Owner

Approval: Signature on File_____________ Date: 01/20/2004 Robert Meyer, TBD Leader

Approval: _ Signature on File ____________Date: 01/20/2004

Judson L. Kenoyer, Task 3 Manager

Concurrence: _ Signature on File _________Date: 01/28/2004

Richard E. Toohey, Project Director

Approval: __ Signature on File __________ Date: 01/30/2004 James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

Record of Issue/Revisions ...................................................................................................................

Page

3

Acronyms and Abbreviations ...............................................................................................................4

2.1 Introduction................................................................................................................................. 5

2.2 Purpose ......................................................................................................................................5

2.3 Scope .........................................................................................................................................5

2.4 Site Activities and Processes ......................................................................................................5

2.4.1 History and Mission .............................................................................................................6

2.4.2 Site Development ................................................................................................................6

2.4.3 Functional Areas..................................................................................................................7

2.4.3.1 Component Manufacturing.........................................................................................7

2.4.3.2 Material Recovery and Purification .......................................................................... 10

2.4.3.3 Process Waste ........................................................................................................ 12

2.4.3.4 Research and Development .................................................................................... 13

2.4.3.5 Plant Support........................................................................................................... 15

2.5 Releases to the Outdoor Environment ...................................................................................... 16

2.5.1 Airborne Emissions............................................................................................................ 16

2.5.2 Waterborne Emissions....................................................................................................... 17

2.6 Accidents ..................................................................................................................................17

2.6.1 Accidents and Contamination Control................................................................................ 18

2.6.2 Accidents Involving Plutonium ........................................................................................... 18
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2.6.3 Tritium at Rocky Flats ........................................................................................................ 23

2.6.4 Accidents Involving Uranium.............................................................................................. 24

References ........................................................................................................................................25

Glossary ............................................................................................................................................26

2A Rocky Flats Buildings and Operations ........................................................................

Attachments

32

2B Rocky Flats Job Titles and Descriptions .....................................................................42

2C Operational Accidents and Incidents at Rocky Flats Plant .......................................... 44

2D Figures .......................................................................................................................46

2E Partial List of Potential Hazards Associated with Various Job 

Descriptions and Locations.........................................................................................56

LIST OF TABLES

Table

2-1 Plutonium release estimate distributions by event..................................................................

Page

23

LIST OF FIGURES

(Attachment 2D)

Figure

1 Location of the Rocky Flats Plant in Colorado........................................................................

Page

46

2 Rocky Flats facility as it appeared in 1990 ............................................................................. 47

3 Rocky Flats ponds and creeks ............................................................................................... 48

4A Rocky Flats site waste disposal areas.................................................................................... 49

4B Rocky Flats site waste disposal areas.................................................................................... 50

5 Plutonium air emission sources.............................................................................................. 51

6 Reported gross alpha radioactivity emissions from Rocky Flats plutonium facilities ............... 52

7 Sites of major accidents at the Rocky Flats Plant................................................................... 53

8 Tritium air emissions sources................................................................................................. 54

9 Uranium air emission sources ................................................................................................ 55
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 09/04/2003 00-A Technical Basis Document for the Rocky Flats 

Plant – Site Description. Initiated by Robert 

Meyer.

Draft 09/12/2003 00-A Incorporates updated references. Initiated by 

Robert Meyer.

Draft 09/24/2003 00-B Incorporates informal comments from B. Ulsh, J. 

Shipman, J. Kenoyer. Initiated by Robert Meyer.

Draft 12/19/2003 00-C Incorporates OCAS and ORAU comments.

Initiated by Robert Meyer.

01/10/2004 01/10/2004 00 First approved issue. Initiated by Robert Meyer.
Effective Date:01/10/2004 Revision No. 00 Document No. ORAUT-TKBS-0011-2 Page 4 of 58

ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

AEDE Annual Effective Dose Equivalent 

CAM continuous air monitor

CCl4 carbon tetrachloride

D&D decontamination and decommissioning

DAC Derived Air Concentration

DOE U.S. Department of Energy

DU depleted uranium

EEOICPA Energy Employees Occupational Illness Compensation Program Act

HEPA high-efficiency particulate air (filters) 

HEU highly enriched uranium

IREP Interactive RadioEpidemiological Program

MDA Minimum Detectable Activity

NIOSH National Institute for Occupational Safety and Health

NTA Nuclear Track Emulsion

MSE Molten Salt Extraction

OCAS (NIOSH) Office of Compensation Analysis and Support 

ORAU Oak Ridge Associated Universities

PA posterior-anterior (medical X-ray)

PPE Personal Protection Equipment

R Roentgen

RBE Relative Biological Effectiveness

RCT Radiation Control Technician

rep Roentgen equivalent physical

RFP Rocky Flats Plant

TBD technical basis document

TCA 1,1,1 - trichloroethane

TCE trichloroethylene

TLD thermoluminescent dosimeter

TRU transuranic

ZPPR Zero Power Plutonium Reactor
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2.1 INTRODUCTION

The National Institute for Occupational Safety and Health (NIOSH) is responsible for developing the 

technical capabilities and guidance for the implementation of the Energy Employees Occupational 

Illness Compensation Program Act (EEOICPA). Oak Ridge Associated Universities (ORAU) leads a 

team, the ORAU Team, to support NIOSH in the performance of this program. This technical basis 

document (TBD) represents a specific area of support to the ORAU Team related to documentation of 

historic practices at the Rocky Flats Plant (RFP). The information in this document is for the 

evaluation of internal and external exposures to unmonitored and monitored workers and may either

supplement or substitute for individual monitoring data. 

2.2 PURPOSE

The purpose of this TBD is to provide a RFP profile that contains technical basis information used by 

the ORAU Team to evaluate the total occupational dose for EEOICPA1

2.3 SCOPE 

claimants. This section 

provides information on RFP facilities and operations.

RFP operations played an important role in the U.S. nuclear weapons program. Operations included 

production of fissionable material components. This TBD contains supporting documentation to assist 

in the evaluation of worker dose from RFP operations and processes. Additional guidance is found in

OCAS-IG-001, External Dose Reconstruction Implementation Guideline (NIOSH 2002a) and OCASIG-002, Internal Dose Reconstruction Implementation Guideline (NIOSH 2002b). 

The methods used to measure radiation exposure to workers have evolved since the beginning of 

RFP operations. An objective of this TBD is to provide supporting technical data to evaluate the total 

RFP occupational dose that can reasonably be associated with worker radiation exposure as covered 

under EEOICPA. This dose includes occupational external and internal exposure in RFP facilities, 

RFP occupationally required diagnostic X-ray examinations, and onsite exposure to RFP 

environmental releases. The document addresses evaluation of unmonitored and monitored worker 

exposure, and missed dose. 

In addition, this TBD presents Information on measurement uncertainties, and describes how the 

uncertainties for RFP exposure and dose records are evaluated. 

Section 2 describes RFP facilities and processes. Sections 3 through 6 provide historic information 

related to worker medical X-ray, internal, and external exposures, and environmental data for use if 

outdoor monitoring data are unavailable. Attachments related to sections 3 through 6 provide detailed 

data and tables for dose reconstructors to perform dose reconstructions.

2.4 SITE ACTIVITIES AND PROCESSES

A comprehensive history of the Rocky Flats Plant was prepared as part of Rocky Flats health studies 

conducted by the Colorado Department of Public Health and Environment during the 1990s (see 

reference list). Information in this TBD section is from these 1990s reports except as otherwise noted. 

 

1. The Energy Employees Occupational Illness Compensation Program Act, Public Law 106–398, provides for the 

payment of compensation benefits to covered employees and, where applicable, survivors of such employees, of the 

U.S. Department of Energy, its predecessor agencies, and its contractors and subcontractors.
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2.4.1

The U.S. Atomic Energy Commission announced its decision on March 23, 1951, to build the Rocky 

Flats Plant in Colorado (see Figure 2-1). Ground-breaking occurred in July of 1951 for what is now 

building 991. In general, the primary mission and general activities at the plant remained essentially 

the same from the time the plant opened until 1989, when the U.S. Department of Energy (DOE) 

suspended plutonium operations. The Rocky Flats site had two major missions – production of 

plutonium triggers (or “pits”) for nuclear weapons and processing of retired weapons for plutonium 

recovery. From the beginning the plant was a manufacturing facility. Plutonium triggers are 

components of fission bombs, used to initiate the second-stage fusion reaction in hydrogen bombs. 

The plant received plutonium from production sites (the Savannah River and Hanford Sites), and from 

retired warheads and residues. Parts were formed and machined from plutonium and uranium, and 

beryllium, stainless steel, and other nonradioactive materials (ChemRisk 1992).

History and Mission

In 1984, the site was proposed as a Superfund site and, in 1989, it was included on the National 

Priorities List for cleanup of environmental contamination. In December 1989, DOE suspended 

plutonium processing to review and upgrade the plant’s safety systems. EG&G, Inc., assumed 

operation of the site on January 1, 1990, working toward the resumption of operations in the 

plutonium buildings. With the President’s 1992 announcement of cancellation of the W-88 Trident 

Warhead Program, the Rocky Flats production mission ended permanently. In 1993, the Secretary of 

Energy formally announced the end of nuclear production at Rocky Flats. In 1994, the last defense 

production-related shipment was sent from Building 460. Kaiser-Hill is now managing permanent site 

closure, planned for completion in 2006.

There have been only three basic pit designs since the beginning of plant operations, with the 

manufacturing of the first two designs phased out within the first 5 years of production. The first two 

designs built at Rocky Flats were solid units made mostly of uranium. Design changed around 1957 

to focus primarily on plutonium (ChemRisk 1992). 

2.4.2

The following paragraphs describe the chronological development of RFP facilities and operations. 

Figures at the end of this section show the location of these facilities as they were constructed. 

Attachment 2A lists facility functions by building.

Site Development

1951–1954

Ground-breaking for the first permanent buildings at the Rocky Flats Plant began in July 1951 for what 

is now known as Building 991. Later that year, construction began on Buildings 771, 444, and 881. 

By April 1952, production operations reportedly had begun, but no production or shipment details are 

available for 1952 or the first part of 1953. At the beginning of 1953, some of the onsite utility facilities 

were still incomplete; water came from Boulder in tank trucks, and a locomotive brought to the site 

provided steam heat. Nevertheless, the first products were completed and shipped that year. By 

1954, the plant was fully operational, with initial construction essentially complete with about 700,000 

square feet of building space. Employment grew steadily from 133 people in 1951 to 3,101 in 1963.

Originally, the plant had four operational areas – A, B, C, and D Plants –- identified according to four 

primary types of work. The A Plant included Building 444 operations, which involved the fabrication of 

depleted uranium parts. Later known as Building 881, the B Plant recovered enriched uranium and 

manufactured enriched uranium components. The C Plant (later Building 771) housed plutonium 

operations, and the D Plant in Building 991 was the center of final product assembly operations. 

There were large spans of meadow between the areas, with gravel roads connecting them. Very few 
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people had clearances to get into more than one building, and most employees had no idea what 

occurred in areas other than their own. Plant employees were bussed from the front gate to their 

buildings, because personal vehicles were not allowed on the site. 

1955

A major facility expansion began in 1955, referred to as Part IV construction.

1956–1957

This period saw the construction of Buildings 447, 776, 777, 883, 997, 998, and 999; and the 

expansion of Buildings 444, 881, and 771. These additions were directly related to the change of the 

weapon concept to a hollow unit and anticipated production increases. A few years later, roughly 

coincident with the onset of the Cold War, RFP became the primary manufacturer of pits under the 

single-mission concept. The result was a dramatic rise in production at the plant in the 1960s. By 

1964, the workforce reached a level of around 3,000 people that lasted for about 15 years. 

1967–Early 1970s

Buildings 559, 440, 707, 750, and 865 were constructed.

Early 1980s–1990

DOE built Buildings 371 and 460 during this period. The period showed a significant upturn in Rocky 

Flats employment, with a peak at 5,990 in 1984.

By 1990, total building space had grown to approximately 2.5 million square feet. Figure 2-2 shows 

the 1990 RFP layout, including the structures identified in the previous paragraphs.

2.4.3

Rocky Flats operations included the following functional areas:

Functional Areas

• Component Manufacturing and Assembly

• Material Recovery and Purification

• Research and Development

• Waste Processing

• Plant Support

To manufacture a fissionable product, RFP developed facilities, equipment, and personnel to conduct 

precision metalworking and to assemble fissionable and nonfissionable materials. Key nonfissionable 

components were made of beryllium, aluminum, and stainless steel. 

Early work at the plant involved both 235U and 239Pu as fissionable materials. Enriched uranium 

contract work transferred to the Oak Ridge Reservation in 1964. Americium-241 recovery did not 

start until 1957, functioning as a step in the plutonium recovery process and producing a marketable 

product. Beryllium was not used in full-scale production operations until 1958. Stainless-steel

component work began in 1966. Stainless-steel operations (known as the "J Line”) took place in 

Building 881 until 1984, when they moved to Building 460. 

2.4.3.1 Component Manufacturing

When the A Plant (Building 444) started operations in 1953, it was devoted entirely to depleted 

uranium manufacturing. Operations included casting and machining of components. While no details 

are available, processing of depleted uranium is not generally considered to be a significant hazard 
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from either an external (photon) or internal (alpha-emitter) perspective. RFP originally received 

depleted uranium from Paducah, Kentucky and, later, as feed material from the Feed Materials 

Production Center in Fernald, Ohio, as ingots in sealed cans. While TBD reviewer comments indicate 

that Paducah was processing recycled U beginning in 1953, available Rocky Flats records do not 

indicate whether fission product or TRU-contaminated U was processed at Rocky Flats.

Enriched uranium operations occurred in B Plant (Building 881), and initially involved a heavy 

workload. The basic operations involved casting and machining. The components were solid pieces 

of uranium, machined to particular shapes, which were assembled with plutonium, stainless-steel, and 

depleted uranium components in D Plant. 

With development of new designs, the revised concept required a significant amount of rolling and 

forming of depleted and enriched uranium, and space in existing facilities became inadequate. 

Building 883 was built to handle the rolling and forming of uranium. Depleted uranium was cast in 

Building 444, but was shipped to Building 883 to be heated and rolled into sheets from which blanks 

were cut and formed to the required shape. The shaped pieces were shipped back to Building 444 to 

be turned, trimmed, and polished. In some cases, the component was coated with protective 

materials. 

Building 883 was designed with two functional areas to prevent cross-contamination; the B side 

handled enriched uranium, and the A side rolled and formed depleted uranium. The plant was so 

pressed to begin production of the new type of weapon components that operations began in Building 

883 before the roof was completed. To prevent emissions from these early operations and to protect 

machinery and materials from the elements, enclosures were placed around the process equipment. 

Details concerning early ventilation and other worker protection systems during this period were not 

found in the available literature.

Research and development (R&D) of depleted uranium-niobium alloys involved an electron-beam 

furnace. Alloying work began in 1966, although full-scale production did not occur until the early 

1970s. An arc furnace installed in the mid-1970s provided the capability to produce depleted uraniumniobium alloys. This furnace melted elements such as zirconium and niobium more effectively than 

induction casting furnaces, thereby creating a more homogenous alloy casting. 

In the early 1960s, Building 881 was idle while the enriched uranium areas were decontaminated and 

decommissioned. Conversion to accommodate stainless-steel operations began in 1966. Machining 

of depleted uranium continued in Building 444. In 1964, the B side of Building 883 was converted to 

beryllium rolling and forming. 

After the Oak Ridge Reservation took over enriched uranium operations in 1964, it supplied RFP with 

finished uranium components for incorporation in final pit assemblies. RFP still received site returns 

that contained enriched uranium components. The plant processed those components with a spray 

leaching process to remove external plutonium contamination, and returned the oralloy parts to Oak 

Ridge for reprocessing. Oralloy leaching operations were originally in Building 881, but were moved 

to Building 771 in the mid-1960s. The oralloy leaching process remained in Building 771 through 

1989 (ChemRisk 1992).

Early during facility operations, C Plant (Building 771) housed essentially all plutonium manufacturing 

and recovery. In the early years, plutonium metal was machined in a dry state (i.e., without oils, using 

only carbon tetrachloride as a coolant), with as little machining as possible. Handling the dry material 

required extra care to prevent spontaneous combustion. Plutonium components were cast, pressed 

into shapes, minimally machined to true them, and plated with cadmium, which enabled handling with 
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reduced personnel exposure to neutrons and alpha particles. The first weapons were designed such 

that they were to be armed (final assembly) in the aircraft on the way to the target. The protective 

coating grounded the parts against static electricity that might be generated while handling them in the 

field. The coating changed to nickel within a few years, using a process that employed nickel 

carbonyl. The use of nickel carbonyl lasted at least into the late 1960s, although its use in later years 

was reduced, due to design changes that enabled remote arming. 

Building 776 machining operations (also involves Bldgs. 771, 777, 881, 460, 991, 707, 881, and 

444) 

Higher-volume machining of plutonium began in 1958, with new operations in Building 776 using Shell 

Vitrea, a cutting oil, followed by washing with carbon tetrachloride. Building 776 housed a centralized 

collection and separation point, and the solid and liquid fractions were sent separately to Building 771. 

In Building 771 most of the carbon tetrachloride was distilled from the oil, and the plutonium cuttings 

were recovered from the solids. At that time, Building 777 was the focal point for assembly 

operations. Facility staff members were unable to develop a satisfactory method for handling spent 

oils and residual solvents, which were placed in storage barrels outdoors to the east of the plant. 

Buildings 776 and 777 went into service in 1958 to handle the increased plutonium workload, and 

Building 771 undertook recovery operations. Building 776 performed plutonium machining; Building 

777 handled assembly operations. Building 991 was used for storage and R&D, although it was 

several years, (records indicate 1960), before all assembly operations had left the building. In 1969, 

a major fire in Buildings 776 and 777 resulted in some operations moving to other buildings. The 

machining and foundry operations in the fire-damaged areas of Building 776 became part of the 

operations in the new 707 assembly building. Those operations remained in Building 707, and solid 

waste treatment operations and size reduction moved into Building 707 after Building 776 returned to 

operation in 1972. (Building 776 in 1972 was being used for waste storage and waste size reduction.)

Final assembly of the early products was initially a relatively simple operation. The original final 

assembly building was D Plant, now known as Building 991. Later, the hollow-core weapons design 

involved more assembly complexity. As a result, Building 777 in 1957 began to provide assembly 

facilities. Operations involved drilling, welding, brazing, turning, and polishing. Building 707 began 

final assembly operations shortly after the 1969 fire, which shut down Buildings 776 and 777. Final 

assembly operations occurred in Building 707 through 1989. 

Stainless-steel operations, the J-Line, began in Building 881 in 1966 and remained there until the 

completion of Building 460 in 1985. Stainless-steel operations from Building 881 and some 

operations from Building 444 were consolidated in Building 460 at that time. A significant portion of 

the stainless-steel work was the fabrication of empty tritium reservoirs. The reservoirs were later filled 

with tritium gas under high pressure at the Savannah River Site 

In 1957, the new weapon design required beryllium components. There had been some beryllium 

operations in Building 444 in preparation for regular pit production, and in 1958 beryllium operations 

became a significant portion of RFP activities. The components manufactured in Building 444 no 

longer went directly to the Pantex Plant. Rather, they were incorporated in the final assembly 

operations in Building 777. The depleted uranium workload decreased significantly as beryllium use 

increased (ChemRisk 1992). 

Beginning in 1952, thorium was used onsite in quantities small enough that effluents were not 

routinely analyzed for Th. Thorium quantities varied from as little a none to as much as 238 kg in a 

given month. The principal use was fabrication of metal parts from natural thorium metal (232thorium) 

and from various thorium alloys. Thorium oxide might have been used as a mold-coating compound 
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in limited experiments. Thorium compounds were used in analytical procedures. In addition, twice 

between 1964 and 1969, thorium “strikes” were performed to remove gamma-emitting 228thorium from 

uranium-233 metal needed for fabrication of test devices. The strikes involved a fluoride precipitation 

and filtration process using natural thorium. Photon radiation from 228Th decay products would have 

been monitored by standard gamma dosimetry badges in use at the plant. In addition, thorium was 

used as a stand-in for plutonium or uranium components in development programs (ChemRisk 1992).

2.4.3.2 Material Recovery and Purification

Manufacturing produced wastes, which consisted of fissionable and nonfissionable materials, 

associated lubricating and cleaning compounds, and other materials such as rags, slags, clothing, 

tools, and paints. Wastes were stored in barrels in the 903 area just outside the main fence. In the 

late 1960s, waste oils were eventually treated by fixation in concrete and shipped off the site for 

burial. Cleanup of the 903 area resulted in some potential for worker exposure to airborne plutonium

from disturbance of contaminated soil.

Plutonium Recovery and Purification

When Building 771 became operational in 1953, operations included plutonium recovery (from 

weapons manufacture and later from weapons recycle) and purification, and plutonium component 

manufacturing. Plutonium operations patterned after Los Alamos plutonium facility work began in the 

spring of 1953. Only one "Chem Line" was in operation; it had the capacity to produce plutonium 

buttons of approximately 300-gram mass. Later, in 1955, an "East Chem Line" started, with the 

capability to produce 2-kilogram buttons. Eventually, operational capacity reached 12 kilograms per 

day. In 1965, an expanded production area added five dissolution lines, increasing plutonium 

recovery by a factor of 20 over that of the original line (ChemRisk 1992). In 1968, the decision was 

made to replace Building 771 recovery operations. Groundbreaking took place in 1973 for what was 

to become Building 371. The new facility was plagued with problems from the onset of construction, 

and delays prevented cold startup before 1981. Design flaws resulted in the shutdown of Building 371 

chemical processing in 1985 before achieving full-scale operation. 

Originally, plutonium at Rocky Flats came from Hanford as plutonium nitrate in small stainless-steel 

flasks packaged in cylindrical steel carrying cases. The nitrate was vacuum-transferred into a vessel 

in which plutonium dioxide was precipitated. Chemical reduction converted the dioxide to metal 

buttons. Later, plutonium was received from Hanford in the form of buttons. Occasionally, plutonium 

nitrate feed was received from the Oak Ridge Reservation. In 1959, these shipments were reduced, 

and most of the plutonium feed to recovery and purification operations became recycled material from 

site returns, the foundry, or waste products from the recovery operation. Some plutonium that went 

through the system at this time came from outside sources in the form of plutonium dioxide. Later

shipments of plutonium consisted of metal buttons from the Savannah River Site. 

RFP produced components from other metallic radionuclides on a limited basis for incorporation in 

pits for special-order operations. The inclusion of these radionuclides (237neptunium, 241

americium, 

238plutonium, and 244curium) as tracers into the makeup of the pits enabled research elsewhere. The 

Special Recovery area processed the plutonium tracer materials. Eventually, leftover tracer materials 

had to be removed from the plutonium streams, which became part of Special Recovery operations. 

Special Recovery operations included the Oralloy and Part V Leaching lines, in which surface 

impurities were removed from enriched uranium and plutonium components.

The recovery process was often described in terms of functional divisions - "fast" and "slow" recovery 

operations. The fast cycle processed plutonium nitrate solution, turning the liquid to a solid (powder) 

and then to metal. The slow cycle received materials with higher concentrations of impurities 
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(requiring a greater degree of preprocessing before entering the fast cycle metal conversion process). 

Before the implementation of the molten salt extraction process in 1968, almost all plutonium-bearing 

materials went through slow recovery operations. These materials had to be converted to plutonium 

nitrate via the slow cycle and then introduced into the fast cycle line for conversion to a solid and 

reduction to metal. Since the introduction of the molten salt extraction (MSE) process in 1968, some 

of the essentially pure plutonium metal, such as the metal from site returns, went through MSE to 

remove americium ingrowth and then directly to plutonium foundry operations in Building 777 for 

casting and subsequent processing into plutonium components. As a result, slow cycle recovery 

received such materials as effluents and waste products from the fast cycle, rags, paper goods, 

sweepings, and other wastes. It no longer processed the purer forms of plutonium.

Slow recovery operations involved a variety of processes. For example, combustible residues such 

as plastic bags and Kimwipes were incinerated to reduce material bulk and to convert the plutonium 

into an oxide form. Before 1960, dissolution was followed by a solvent extraction step that used 

tributylphosphate as the solvent and dodecane as the diluent. The solvent extraction was followed by 

cation exchange. Around 1960, solvent extraction was eliminated from the recovery process line 

because the materials going through the recovery process were becoming more and more varied 

(ChemRisk 1992).

Uranium Recovery and Purification

Building 881 was built in 1952, and housed enriched uranium component manufacturing, including 

machining and fabrication of parts. When the chemical recovery line began enriched uranium 

recovery from metal residues created in the manufacturing processes in 1954, Building 881 housed all 

enriched uranium operations, from casting to forming, machining, assembly, recovery, and 

purification. The raw material came from the Oak Ridge Reservation, primarily in the form of hockeypuck-size “buttons" of pure metal. 

Uranium recovery operations in Building 881 were modeled after processes developed during and 

after World War II at Los Alamos and the Oak Ridge Reservation. The Building 881 process was 

similar to the 1950s plutonium recovery process that included solvent extraction. Uranium recovery 

had fast and slow sides and involved similar chemistry, but dibutylethylcarbutol was used as the 

solvent, rather than the tributylphosphate and dodecane used as the solvent and diluent, respectively, 

in plutonium recovery. Overall, the basic plutonium and uranium recovery operations were similar 

(ChemRisk 1992). 

Americium Recovery

There was a pressing need to deal with the americium in the plutonium handled at RFP, because ingrowth of 241Am from 241Pu decreases the effectiveness of the plutonium and creates a gamma 

exposure problem. The plant had a backlog of americium-containing sludge generated from a 

plutonium recovery process. As a result, in 1957 an americium line began operation in Building 771. 

From the late 1950s until the late 1970s, americium was recovered and purified at the plant for resale. 

The demand for americium declined in the late 1970s, and the americium removed in the plutonium 

purification process went to Building 774 to be processed as a radioactive waste. Information for this 

period concerning the chemical form of extracted 241Am was not discovered during our review.

Americium operations were limited to MSE operations needed to purify plutonium metal.

In 1962, a slight change was made to the ammonium thiocyanate process by adding oxalate 

precipitation and calcination steps, which resulted in an americium oxide product that was preferred 

because of its stability. The process during this period was cumbersome, resulted in a 

disproportionate quantity of waste solutions, and created personnel alpha-contamination exposure

problems due to required manual operations and maintenance. 
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In 1967, the MSE process became the feed source for americium purification. In MSE, molten 

americium-bearing plutonium came into contact with molten NaCl-KCl-MgCl2 salt. Oxidationreduction reactions with the salt separated the americium from the plutonium by equilibrium 

partitioning. There were alpha-contamination personnel exposure problems associated with the 

hydroxide precipitation step, and in 1973 it was replaced with a cation-exchange procedure. The 

entire process underwent another major change in 1975, when the ammonium thiocyanate steps were 

eliminated and the americium was recovered from the anion effluent by oxalate precipitation with 

subsequent calcination to form the more stable oxide.

After 1976, MSE salts were sent to a “salt scrub” process rather than to americium purification. (A salt 

scrub removes Am and Pu from MSE salts.) Salt scrub made a "scrub alloy" of americium, plutonium, 

and gallium that was shipped to Oak Ridge for further processing. Americium recovery and 

purification operations shut down in 1980, and work was limited to that required to extract americium 

from plutonium metal in site returns (ChemRisk 1992).

2.4.3.3 Process Waste

When Building 774 was built in 1952, its primary purpose was to support Building 771 by treating its 

radioactive aqueous waste. The general mission of the waste operations was to reduce the volume of 

wastes. Liquids transferred to Building 774 were subjected to pH adjustment and sent through a 

precipitation step to remove radionuclides. The resulting slurry was sent to vacuum filters. The solids 

removed from the filters were combined with cement or another solidifying agent and shipped to longterm storage as transuranic (TRU) mixed waste. The aqueous waste from this first stage went 

through the process again. Before 1973, aqueous wastes from this process went to either the solar 

evaporation ponds or to the "B" series of holding ponds, depending on the concentrations of 

radioactivity. Maintenance and eventual cleanup of the solar ponds introduced potential worker 

exposure scenarios (Meyer and Till 1999).

Around 1965, an evaporator was installed in Building 774 to treat liquids that had accumulated in the 

solar evaporation ponds. Water and volatiles evolved from the evaporation process were discharged 

to the atmosphere. The concentrate from the evaporator was fed to a double drum dryer, on which 

the salt solution dried for removal by a scraping blade. Water vapor and volatiles from the dryer went 

through a scrubber and demister before venting to the stack, with the liquids from the scrubber and 

demister returning to the aqueous treatment process. The evaporator was removed from service in 

1979, and liquids from the second stage of treatment and the solar ponds were transferred to Building 

374. Figure 2-3 shows the locations of these ponds.

Building 374 went into operation in 1980 as an integral part of the new plutonium recovery facility, 

Building 371. Building 374 was designed to handle wastes generated in Building 371. The processes 

used in Building 374 were essentially the same as those used in Building 774, with more efficient 

equipment. Building 374 was also designed to provide greater safety of operation through improved 

containment, control systems, and separation of workers from operations.

While most hazardous and radioactive wastes were shipped off the site for disposal, approximately 

178 inactive waste sites existed within the plant boundaries as production operations were completed 

in the late 1980’s, some of which had been the sites of burial, incineration, and land application 

(ChemRisk 1992). 

Liquid sanitary waste operations were kept separate from the liquid process waste operations to 

prevent contamination of the sanitary waste streams. Holding tanks upstream from the treatment 

plant were sampled to check for plutonium contamination. Standard waste treatment was provided. 
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Final disposition of sludges has changed over the years. From 1954 to 1968, 100 tons of sanitary 

sludges were disposed of in onsite trenches (T-2 through T-8). At that time, some floor drains in the 

manufacturing buildings were not isolated from the sewage treatment plant, and the sanitary sludge 

became contaminated with uranium and plutonium. A second landfill that opened in 1968 received 

sludges until 1969. At that time, the sludges were declared low-level radioactive waste and shipped 

off the site to approved disposal sites. 

There were instances of onsite burial of contaminated materials, most notably soils that were 

contaminated as a result of the 1969 fire and other soils excavated during cleanup of the laundry 

waste outfall formerly located on the north side of Building 771. In the early years of plant operation, 

laundry waste was discharged directly to Walnut Creek. The released water met then-current 

standards for concentrations of plutonium and uranium. On December 21, 1973, the release of 

laundry waste to Walnut Creek ended.

The original RFP landfill, on the south side of the plant, opened in 1952 and closed in August 1968. 

An incinerator was in operation at that time, in Facility 219 on the west access road. With a few 

exceptions, nonradioactive combustible waste was burned in the incinerator and the resultant ashes 

were buried adjacent to the incinerator. It is estimated that fewer than 100 grams of depleted uranium 

were incinerated in general plant waste between 1952 and 1968 (ChemRisk 1992).

Figure 2-4 shows the locations of waste disposal areas at the site.

2.4.3.4 Research and Development

Rolling of enriched uranium foil was conducted in 1964 in the northeast comer of the plant garage, 

Building 331. Interviews suggest that this area was also used for the development of depleted 

uranium and uranium alloy casting techniques, using electron beam heating, and uranium coating 

studies until Building 865 came on-line in 1970 (ChemRisk 1992). 

In the mid-1960s, R&D work became a larger part of the activities at the plant, as Buildings 779, 559, 

and 865 were constructed. Much of this work focused on examining site returns to determine the 

effects of time and field conditions on the weapons, including corrosion and other forms of 

deterioration. 

Building 779, a plutonium R&D facility, was constructed in 1965. Its purpose was to study the 

chemistry and metallurgy of plutonium and its interactions with other materials. In addition, Building 

779 housed efforts to develop improvements to manufacturing processes, to find new ways to recover 

plutonium and associated actinides, and to better understand the aging characteristics and shelf-life of 

RFP products. 

Building 865 began operations in 1970. It served as an R&D facility primarily for manufacturing 

processes using uranium and beryllium. The work involved metalworking and metallurgy techniques. 

The metallurgical operations involved the development of alloys and alloying processes, and 

fabrication of prototype hardware. Metalworking operations include melting and casting, forging, 

press forming, extrusion, drawing, rolling, diffusion bonding, hydrospinning, swaging, cutting and 

shearing, and heat treating. In addition, glove-box operations involved high-purity beryllium powder 

and machining operations that generally involved nonfissionable materials.

After 1964, Building 881 became a multipurpose facility for research and development, analytical 

work, plant support, and administrative offices. Operations included analytical laboratories, 

generation of chemical standards, activities to machine small parts for weapons and energy 
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generation research, gold plating of parts, assembling microscopic parts, and some large machining 

operations. The Special Weapons Projects group was involved in the development of engineering 

prototypes and full-scale models for military training. Recovery Technology activities included 

materials development, process instrumentation and control, and equipment design and development. 

The Waste Chemistry group supported engineering and development of onsite waste treatment 

processes, and Joining Technology conducted operations to join non-nuclear metals including 

beryllium, in some cases using brazing alloys including nickel. Other operations in Building 881 

included Nondestructive Testing, Records Management and Storage, and various maintenance shops 

and activities.

Explosive bonding experiments occurred at the explosive forming area near Building 993 from 1965 

until approximately 1968. The experiments were designed to explosively bond together flat plates of 

stainless steel and uranium alloy using dynamite. The explosive events took place below grade. No 

information was identified to indicate whether releases to the environment occurred during these 

tests, which typically involved relatively small amounts of explosives (192 grams of 40% dynamite 

were routinely used in the bonding tests). While available records do not indicate the isotopic 

composition of uranium used in these tests, the tests were designed to examine the chemical/physical 

characteristics of the explosive bonding process, and it is unlikely that enriched uranium would have 

been used in such tests. 

Work for Others

The plant conducted Special Order work for other facilities in the weapons complex, the Department 

of Defense, or other Federal departments or agencies. Most Special Order work did not involve 

materials other than types used in production activities. The tracer work noted above was an 

exception. Neptunium-237 tracer work associated with uranium and plutonium components took

place in Buildings 771 and 881. Exact dates of production and later recovery of these tracers (from 

recycled materials) are not readily available – such work was occurring at Rocky flats from the mid60’s to the late 70’s, based on our interpretation of available information. There was considerable 

effort devoted to keeping tracer materials separate from the regular production material streams, and 

Special Recovery operations focused on recovering the materials. 

For the Zero Power Plutonium Reactor (ZPPR) project, RFP manufactured approximately 4,000 

stainless-steel-clad fuel elements consisting of plutonium, molybdenum, and uranium during 1967 and 

1968. The plant manufactured the fuel rods for installation in the reactor at Argonne National 

Laboratory. These elements were made by alloying uranium and molybdenum in Building 444. The 

uranium-molybdenum alloy was sent to Building 771, where it was alloyed with plutonium by casting 

into plates of various sizes. The “ternary alloy” plates were clad in stainless-steel envelopes in 

Buildings 776 and 777 and sealed by welding. The plutonium used in this project originated in the 

United Kingdom and contained a higher percentage of 240Pu than most Rocky Flats plutonium, so the 

project took care to keep it separate from other plutonium recovery and waste streams. TBD Section 5 

provides additional details concerning the radionuclide makeup of ZPPR fuel. 

During the late 1970s and early 1980s, RFP made thousands of calorimeter plates from depleted 

uranium for Sweden, Harvard University, and Brookhaven National Laboratory. In a large project that 

involved processing hundreds of tons of depleted uranium in Building 883 in the mid-to-late 1980s, the 

plant made armor plates for the M1A1 tank. In the mid-1980s, the U.S. Army developed an advanced 

type of layered Burlington armor that incorporated depleted uranium. 

RFP was involved in "Project Plowshare,” the effort to develop technology for using nuclear 

explosives for peaceful applications, such as excavation and uncovering of deep mineral deposits. 
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This involvement lasted from 1959 to the mid-1970s. An objective of the project was to use as little 

fissionable material as possible to limit fission product production. 

2.4.3.5 Plant Support

The plant had a number of support organizations, including administration and finance, utilities, 

facilities management, and health and safety personnel. The plant also had some unusual support 

organizations, including the Criticality Laboratory (or Nuclear Safety Group), which was responsible 

for identifying and directing control of the potential for criticalities in plant activities. Another unique 

support function was provided by the Filter Testing group formed in 1979, which performed pre- and 

postinstallation testing of the high-efficiency particulate air (HEPA) filters used in ventilation exhaust 

systems and of personnel respirators.

The Nuclear Safety Group was at the plant beginning in 1953. At that time, the group did not have its 

own facility. In the early years, the group performed its work in the areas in which production 

materials were handled. The in situ experiments were always subcritical; neutron count rates were 

observed as criticality was approached (ChemRisk 1992).

In more recent years, the Nuclear Safety Group conducted its work in Building 886, which was 

commissioned in 1965. Since that time, this group conducted about 1,600 critical mass experiments 

using enriched uranium, and plutonium, in solutions (800 tests), compacted powder (300), and 

metallic forms (500). After 1983, criticality experiments were not conducted with solid materials; they 

were conducted primarily with uranyl nitrate solutions, which were reused. Building 886 housed the 

Critical Mass Laboratory, some offices, and a small electronics and machine shop. 

Approximately half of the 1,600 criticality experiments in Building 886 achieved criticality. 

Experiments in the RFP laboratory generally involved power levels of no more than 10 milliwatts, for 

no more than an hour. Approximately six high-power experiments were taken to between 10 and 100 

times the power of typical tests. Using a conversion factor of 3xl016 fissions per megawatt-second, 

this power level and duration corresponds to a maximum of 1.01x1012 fissions from a typical RFP 

criticality experiment and a maximum of 1x1014 fissions from a high-power experiment. Records 

indicate that there were no incidents at Rocky Flats in which the power level of fissionable material 

became uncontrollable. The experiments were controlled by bringing the materials slowly to nearcriticality, observing the neutron flux to observe the reaction state. There is no indication in the 

available records that gamma exposure or exposure to created fission products was a worker 

exposure problem during these experiments.

Beginning in 1965, airborne effluents from Building 886 were sampled for radioactive particulates. 

Between 1971 and 1989, reported plutonium effluents from Building 886 were no more than 5% of the 

site total (in 1978) and enriched uranium emissions were no more than 10% of the site total (in 1976).

Release of waterborne radioactivity from the Critical Mass Laboratory was limited to several incidents 

involving spills of uranyl nitrate solution (enriched uranium) and disposal of wastewater from such 

activities as mopping floors. The Laboratory floors were sealed and bermed to contain such spills. 

From the late 1960s to the late 1970s, wastewater from activities such as mopping was collected and 

periodically transferred to the solar evaporation ponds, after sampling and analysis indicated that the 

enriched uranium content of the water was much less than 1 gram per liter. 

The Health Physics Laboratories, located in Building 123, performed analyses of personnel 

dosimeters and all airborne sample analyses, including stack samples and general room air samples. 

The laboratories were originally in Building 441. The Standards Laboratory, in Building 125, prepared 
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analytical stock solutions for the other laboratories and performed analyses on incoming radiological 

sources for quality assurance/quality control purposes. In addition, the Standards Laboratory 

performed equipment calibration and standardization. The Plutonium Analytical Laboratory in Building 

559 conducted analyses to determine the purity of plutonium, concentrations of impurities, and 

makeup of plutonium alloys. The Building 881 Laboratories, also called the General Laboratories, 

opened in 1952 to perform wastewater, sludge, surface-water, and groundwater sample analyses. 

These laboratories analyzed production control samples from Buildings 460 and 444. When enriched 

uranium processes were in operation in Building 881, the laboratories also performed analyses of the 

products. 

The Filter Testing Group formed in 1979 after an audit identified the need for independent in-place 

leak testing of HEPA filters. In-place testing began in response to a filter change, when there was 

visible damage to the filter or the supporting framework, when plenum monitoring indicated a problem, 

and according to the routine testing schedule for that particular bank of filters. In addition, the Filter 

Testing Group conducted quality assurance testing on a fraction of new filters (preinstallation testing).

Laundry Services provided cleaning, sorting, and distribution of coveralls and other reusable garments 

required in the manufacturing areas. Available information does not indicate whether or not there were 

contamination concentration limits on laundry to be processed. Laundry water was sent to the forced 

evaporation operations in Building 374. Before Building 374 became operational in 1980, laundry 

water was sent to the second stage of Building 774 aqueous waste operations and then through the 

Building 774 evaporator if (presumably alpha-emitter) concentrations were above 1,667 pCi/l. Below 

this level, laundry water was sent to Pond B-2. In the very early days, Buildings 881, 771, and 991 

had their own laundry facilities, and Building 444 laundry went to Building 442. Around 1958, Building 

778 became the laundry facility for all plutonium-handling buildings. When enriched uranium 

processing ended at Rocky Flats in 1964, laundry from Building 881 went to Building 778. Beginning 

in 1976, laundry from Building 444 depleted uranium operations was sent to Building 778 (ChemRisk 

1992). 

Attachment 2B lists RFP job categories and descriptions. Attachment 2E is a partial list of types of 

radiation exposures associated with various job categories. The data in Attachment 2E are not 

presumed to be comprehensive, but were developed from several readily available documents.

2.5 RELEASES TO THE OUTDOOR ENVIRONMENT

2.5.1

Section 4 of the Rocky Flats TBD contains details concerning stack and other effluent monitoring 

operations through the life of the facility. The RFP began onsite ambient air monitoring at a single 

station in 1952. By early 1953, 10 onsite stations had been established. The July 1953 monthly site 

survey report states that calibration and regulation of samplers to a flow rate of 2 cubic feet per minute 

(cfm) was under way. In February 1954, Whatman 41 filter paper was substituted for HV70 paper on 

all offsite samplers, because HV70 filters ruptured during the week-long sampling. This implies that 

HV70 filters continued to be used for onsite (daily) sampling. In March 1956, manometers were 

installed on onsite units. In 1969, two more stations were added, for a total of 12 stations (ChemRisk 

1992). Figure 2-5 shows key operations and notes plutonium air emissions associated with each 

facility during 1988. 

Airborne Emissions

For a large part of the operational history of the Rocky Flats Plant, emissions were measured in terms 

of long-lived alpha radioactivity. This was true from 1953 to 1973 for plutonium and americium, and 

from 1953 to 1977 for uranium. From 1974 through 1984, 239/240Pu releases through routine 
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operations were monitored by analytical techniques specific for the radionuclides. Americium-241 

was not included in the monitoring scheme. Between 1985 and 1989, 239/240Pu and 241Am were 

routinely sampled and monitored by alpha spectrometry following radiochemical separation but 241Pu 

was not included. Reporting of total long-lived alpha activity continued for uranium facilities until 

about 1977. Even after 1978, not all uranium isotopes were routinely analyzed. For example, only 

238U and 233/244U emissions were reported for 1978 to 1980 and 1984 to 1989. For 1981 to 1983, only 

total uranium emissions were reported. Beginning in 1974, annual airborne tritium release totals were 

reported in annual RFP environmental reports. In 1974, data were reported for 12 vents, which 

expanded to 18 in 1977 and 23 in 1981 (ChemRisk 1992). 

The largest routine releases of plutonium from RFP facilities occurred before 1975, primarily from the 

Building 771 stack and roof vents on Buildings 776 and 777. The largest routine plutonium releases 

from Building 771 occurred between 1957 and 1965; median release quantities after 1965 were below 

1,500 μCi. After 1970, median annual releases were below 500 μCi. Estimated total plutonium 

emissions, summed from the late 1950s to the mid-1960s, range between 1.3 and 6.5 mCi (RAC 

1999c).

2.5.2

There were two series of ponds at the site. The uncovered and unlined holding ponds were 

constructed on Woman Creek and on the north and south branches of Walnut Creek. The first three 

holding ponds were built in the early 1950s; eight more ponds were added over the years. The 

second series of ponds, called solar evaporation ponds, were built in the mid-1950s to enable the 

evaporation of liquids with low levels of radioactivity but high concentrations of nitrates.

Waterborne Emissions

Beginning in 1953, liquid effluent samples from RFP were collected and analyzed. The extent of the 

monitoring program, the spatial distribution of sampling, and the types of materials measured were 

limited until the early 1970s. Under the auspices of the Waste Disposal Unit, the Water Laboratory, 

which was part of the General Laboratory, conducted the analyses. The major focus of the analyses 

in the 1950s was on monitoring total solids and nitrates. With the exception of special circumstances, 

only gross alpha measurements were made before 1970. In general, there was no monitoring of 

plutonium, beryllium, or organic chemicals during this time, even though laundry wastes from Building 

771 and effluents from the sanitary sewer system were discharged directly to Walnut Creek until 

1974. As a result of the May 1969 fire, routine analyses of effluent and environmental water samples 

for plutonium began in September 1969. Plutonium and uranium were isolated from other long-lived 

alpha emitters by ion exchange, and their concentrations determined by alpha pulse-height 

spectrometry. Uranium recovery was determined by 232U tracers. 

2.6 ACCIDENTS

An extensive review of the Rocky Flats accident history occurred during Phases 1 and 2 of the 

environmental dose reconstruction. Researchers evaluated classified and unclassified accidentrelated databases and documents, resulting in the identification of thousands of small-scale releases 

and "accidents" over the 40-year operating history. Many events reviewed during the investigation 

resulted in releases that passed through filtered building ventilation systems. The associated 

releases were recorded as part of normal plant operating emissions. Attachment 2C is a list of some 

accidents and incidents with potential for worker exposures. Not all of the accidents listed in 

Attachment 2C are known to have been associated with worker exposures; several are included only 

because they were likely to have involved significant disruptive mechanical force.

Figure 2-6 shows gross alpha releases to the environment from 1953 to 1977.
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2.6.1

In 1958, site personnel developed a gamma spectrometer wound counter to confirm the presence of 

plutonium in wounds. In August 1961, 55 Alpha Flashers (later Alpha-Mets) were placed on 

gloveboxes in plutonium areas for workers to self-monitor their hands and identify a failed glove 

before spreading contamination. Introduction of “COMBOs”, combination hand and foot monitors, 

included floor areas in the contamination control program. Twenty continuous air monitors (CAMS) 

were in operation by April 1966 (locations unknown). Room air samplers were placed near exhaust 

ducts. Details concerning monitor types, introduction dates, minimum detectable activities, alarm 

characteristics and related information are provided in Rocky Flats TBD Section 5 where available. 

Additional study on the related topic of exposure of unmonitored workers proximate to Rocky Flats 

fires and other accidents has been identified as an important issue for the Rocky Flats TBD team to 

undertake during follow-up work.

Accidents and Contamination Control

Following the two fires that caused major damage to production buildings in 1957 and 1969, there 

were changes to minimize the occurrence and consequences of fires. To reduce the probability of a 

fire, nitrogen atmospheres, minimal combustible loading in all areas, and improvement of fire 

detection and suppression systems were emphasized. The controlled use of automatic water fire 

suppression systems was included in the design of a new plutonium facility, Building 707, in 1967. 

Criticality concerns were addressed by enforcement of fissile limits and prevention of water 

accumulation. 

Figure 2-7 shows the locations of major accidents at the Rocky Flats Plant.

2.6.2

(NOTE: The information in this section is from ChemRisk 1992.) Fire was a continuous hazard when 

working with plutonium at the plant. For example, RFP data indicate 623 reportable fires (most small) 

between January 1955 and December 1974. Of those fires, 387 occurred in plutonium processing 

areas. For perspective, records and interviews indicate that most fires were small and controlled, 

contained in glovebox or other airflow-controlled systems, and resulted in no inhalation exposure 

hazards to workers.

Accidents Involving Plutonium

The accident report on the 1969 fire states that 164 fires were reported to the Fire Department from 

1966 until the 1969 fire. Of these, 31 involved plutonium, of which 10 occurred in Buildings 776 and 

777. Of the remaining 133 fires, 17 occurred in Buildings 776 and 777. There is no reliable estimate 

of the number of plutonium fires not reported to the Fire Department. 

Chips from plutonium machining operations ignite easily if exposed to the air. Plutonium metal bums 

at a temperature near the 640°C melting point of plutonium, and there is no odor, smoke, or flames 

until other combustibles are involved. Small, relatively insignificant, plutonium fires were part of 

normal operations at RFP, and many such fires were not reported if they were confined in the 

production apparatus and there was no evident risk of human exposure. Emissions from most 

plutonium fires occurring during normal operations passed through multistage HEPA filter systems 

and contributed to normal operational releases of radionuclides. The 1957 fire was a significant 

exception.

The September 11, 1957, Fire

The September 11, 1957, fire (see Voillequé 1999a) began when metallic plutonium casting residues 

spontaneously ignited in a glovebox in Room 180 of Building 71 (later Building 771). The fire spread 
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to an exhaust filter plenum, Rooms 281 and 282, consuming a considerable quantity of filters and 

damaging the ductwork and fan system. No major injuries were reported in this fire. 

Chronology of September 11 and 12, 1957:

10:10 p.m. Fire discovered in Room 180.

10:12 p.m. First fire truck arrived.

10:24 p.m. Carbon dioxide extinguishers first discharged at fire.

10:25 p.m. Fan system ordered on high speed.

10:37 p.m. Water spray nozzles discharged at fire.

10:38 p.m. Water shut off. Fire extinguished in Room 180.

10:39 p.m. Explosion in exhaust system; building evacuated due to contamination.

10:40 p.m. Fans went off.

10:58 p.m. Second fire truck called.

11:10 p.m. Electrical power failed in entire building.

11:15 p.m. Water sprayed on filter bank.

2:00 a.m. Filter fire knocked down.

11:28 a.m. Final fire out.

Smoke from a burning glovebox, detected in a building hallway, led two watchmen to discover flames 

extending 18 inches from a Plexiglas window on a glovebox at approximately 10:10 p.m. on 

Wednesday, September 11, 1957. The fire started in a can of plutonium turnings in the “fabrication 

development line” in Room 180 (first floor) of the plutonium processing and fabrication building 

(Building 771). Because large quantities of plutonium were handled and stored in this area, people 

were delayed in fighting the fire until they could don adequate radioactive contamination protection. 

Attempts to fight the fire with carbon dioxide from hand extinguishers and a 100-pound cart were 

ineffective. A water spray nozzle was effective, although there was considerable uncertainty at the 

time about the potential for criticality. 

During this time, the fire spread to the filters, which introduced hot gases through the ventilation 

booster system and the main exhaust duct. Fires in the box exhaust booster filters and main filter 

plenum on the second floor might have started around this time, but were not discovered until 10:28 

p.m. An explosion of collected flammable vapors in the main exhaust duct at 10:39 p.m. resulted in 

spreading plutonium throughout most of the building. The Building 771 exhaust fans shut down at 

about 10:40 p.m. when power was lost. The only draft would have been that created by the natural 

updraft of the stack and through 100 feet or so of horizontal ductwork that leads to the base of the 

150-175 foot stack. Supply fans might have created a positive pressure inside the building for about 

one-half hour. The fire in Room 180 was controlled at 10:38 p.m., but rekindled several times. The 

main filter fire was controlled at 2:00 a.m., and the fire was officially declared out at 11:30 a.m., 

Thursday, September 12, 1957. 

One of the two prefilter systems leading to the main plenum burned through during the 1957 fire. This 

was a two-stage prefilter system for laboratory gloveboxes and hoods and for the production 

development laboratory on the first floor. The exhaust filter plenum consisted of a long concreteblock-walled room into which individual exhaust systems discharged. The 620 Chemical Warfare 

Service (CWS) 24-inch-square filters were held in a structural steel framework. 

Contamination and Dispersal of Soil from the Building 903 Drum Storage Area

In July 1958, an area just east of the main plant site was designated a temporary storage area for 

contaminated oil drums. Many drums developed leaks due to stored chemical interactions, and 

plutonium-contaminated oil was deposited on the soil. Primarily between 1964 and 1969, the 
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contaminated soil was suspended during windstorms (see Meyer at al. 1996; Weber et al. 1999). The 

area was later covered by an asphalt pad.

The following significant events were associated with the Plutonium-Contaminated Drum Storage 

(903) Area:

• July 1958 - Drum storage area established. During subsequent years, drums that contained 

primarily plutonium-contaminated machining oils were continually added.

• July 1959 - First drum leakage discovered. Rust inhibitor, ethanolamine, was added to drums 

prior to storage to minimize corrosion.

• January 1964 - First evidence of large-scale deterioration of drums reported. Soil 

contamination reported increasing.

• January 1966 - Small building added to filter and transfer contaminated oil from leaking drums 

to new drums.

• January 1967 - Last drums added to storage area; removal to Building 774 began. Oldest 

drums shipped first.

• June 1968 - Last drum shipped to Building 774 for processing. High winds spread some 

contamination.

• July 1968 - Radiation monitoring and mapping of area completed. Levels of 2 × 105

 dpm/g of 

soil to more than 3 × 107

 dpm/g were reported. Penetration from 1 inch to 8 inches was 

reported.

• September 1968 - Preliminary proposal for containment cover prepared by RFP Facilities 

Engineering.

• July 1969 - First coat of fill material applied.

• August 1969 - Fill work completed, paving contract let.

• September 1969 - Overlay material, soil sterilant, and asphalt prime coat completed.

• November 1969 - Asphalt containment cover completed, including four sampling wells.

The first indication that drums were leaking in the field was in 1964. Contamination was detected on 

air samplers at the east fence following high winds. As a result, the storage area was fenced and 

contents of leaking drums were transferred to new drums. Approximately 420 drums leaked to some 

extent; of these, about 50 were totally empty. By the end of 1967, plant officials discovered that soil 

contaminated by the leaking drums had been resuspended in the air and redeposited. 

The quantity redistributed was directly associated with the removal of the drums, which exposed 

contaminated soil; physical activity in the area; and the periodic high winds. In November 1968, 

grading began for applying an asphalt cap over the area. Most of the resuspension occurred between 

July 1968 and July 1969. The highest airborne concentration was 0.34 picocurie per cubic meter, 

measured at a monitor approximately 100 m east of the 903 pad, in the prevailing wind direction. 

Installation of an asphalt pad began in July 1969 and ended in November 1969. A round of soil 
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sampling in a 7-mile radius around the plant was completed in late 1989. Plutonium concentrations 

were highest just east of the plant (ChemRisk 1992). 

The May 11, 1969, Fire

A major plutonium fire started in a glovebox in the North Foundry Line in Building 776 on Sunday, May 

11, 1969 (see Voillequé 1999b). The fire burned for several hours, spreading through combustible 

materials in several hundred interconnected gloveboxes in Buildings 776 and 777. The first indication 

of a fire was an alarm in the Fire Station in the North Foundry Line at 2:27 p.m. The Fire Department 

responded promptly, but on its arrival the fire was moving rapidly through the Foundry Conveyor Line. 

The fire spread through an interconnecting conveyor to the Center Fabrication Line. It was brought 

under control about 6:40 p.m., but continued to burn or reoccur in isolated areas through the night. 

On Monday morning, a fire discovered in a glovebox on the South Foundry Line, which was quickly 

extinguished, caused little damage.

The dense smoke, crowded conditions, and presence of large quantities of combustible material in the 

form of Plexiglas windows and Benelex-Plexiglas shielding made the fire difficult to fight and 

extinguish. The fire did not breach the building roof, and ruptured only a minor part of one exhaust 

filter system. As a consequence, most of the smoke and essentially all of the plutonium remained in 

the building. One fire fighter received a significant internal body burden of plutonium. There is no 

evidence that a criticality incident occurred. The damage to Buildings 776 and 777 and equipment 

was extensive. In addition to actual fire and smoke damage, the buildings were grossly contaminated 

with plutonium. Adjacent buildings sustained minor exterior and interior contamination. After the fire, 

processing and production gloveboxes at RFP were converted to an inert nitrogen atmosphere to 

prevent the spontaneous ignition of plutonium.

The first indication of a fire in Building 776 came from an alarm received in the Fire Station at 2:27 

p.m. The fire captain on duty and three firemen responded to the initial alarm. They arrived at the 

west end of Building 776 at 2:29 p.m. On entering the building they saw smoke coming toward them 

from the east. They proceeded further into the building and observed heavy smoke and fire in the 

North Foundry Line. The fire was out of the top of the line with flames about 18 inches high. One of 

the firemen heard two loud reports and saw two fireballs about basketball size go to the ceiling in the 

area of the North Foundry Line. This occurred while the firemen were laying out a fire hose, and 

before any water had been used on the fire. By 2:50 p.m., there was fire along the top of the NorthSouth Conveyor Line. About this time the firemen on the second floor heard a loud noise and felt the 

floor shake. At approximately 3:20 p.m., the fire was spreading to the rolling mill on the Center Line, 

and at 3:40 p.m. the entire area from Columns G-J and 11-13 was glowing orange through dense 

smoke. There was also a fire in the ceiling in the vicinity of the North-South Conveyor Line.

Pressed plutonium briquettes composed of scrap metal and chips generated during rolling, forming, 

and machining operations self-ignited in metal storage containers in a Benelex and Plexiglas

(transparent plastic materials) storage cabinet in the north line. Heat from the burning plutonium 

ignited the Benelex and Plexiglas in the glovebox line, which created large quantities of smoke. 

Visibility was nonexistent due to thick black smoke and the loss of lights in the main fire area. The 

crowded conditions in the fire areas made firefighting very difficult. The first attack on the fire with 

carbon dioxide was ineffective. Less than 10 minutes after the fire alarm was received, the fire 

captain initiated the use of water. Water was used on the fire almost exclusively, although some 

magnesium oxide was used on plutonium. 

Because the conveyor lines and gloveboxes were open, it was impossible to avoid getting water on 

the burning plutonium. As the glovebox windows burned, plutonium oxide was released to the room. 

Because of the extensive plutonium contamination and smoke, personnel entering the area during the 
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fire were required to use self-contained breathing systems, which severely limited their time in the fire 

area. Attempts to pry or knock Benelex shielding from gloveboxes and conveyor lines were not 

successful. Although the firefighters were generally successful in “knocking down” the fire in some 

locations, by the time they returned with new air supplies or from directing their attention to other 

areas, the fire was again intense. 

Some smoke came out the west end doors of Building 776, which were opened at about 2:29 p.m. 

Between 3:20 p.m. and 4:10 p.m., smoke was observed coming from the roof of Building 776. The 

smoke billowed over the side of the building toward Buildings 778 and 750. Firefighters sent to the 

roof saw smoke coming from exhaust vents. Although there were no signs of fire in the roof, the roof 

did soften in one area near the location of the 4 High Mill, Columns H-G and 6-7. The roof was 

sprayed with water and a fire watch maintained until after 5:00 p.m. By 6:40 p.m., the fire was 

contained. Between 7:00 p.m. and 8:00 p.m., a door on the second floor of Building 776 was opened 

and the main building exhaust system was changed from recirculating to single-pass in an effort to 

help clear the heat and smoke. By 8:00 p.m. the fire was largely extinguished, and a fire watch was 

established. During the early morning hours of Monday, May 12, the storage container in Glovebox 

134-24 on the North Foundry Line continued to smolder and reignite. Water and magnesium oxide 

were used on this container. Between 8:00 a.m. and 9:00 a.m. on Monday the fire watch discovered 

a fire in the plutonium storage box on the South Foundry Line (Glovebox 134-70). This fire was 

quickly extinguished by breaking the Plexiglas windows and using water on both the inside and 

outside of the box. This was the only fire in the South Foundry Line.

The fire destroyed the gamma radiation alarm system in Building 776, but the Building 777 alarm 

system remained operational. Neither this system nor those in Buildings 559, 779 and other locations 

on the plant were set off during or after the fire. A Hurst dosimeter retrieved from Building 776 

showed no evidence of being exposed to neutrons or gamma radiation. No one reported seeing a 

visible flash or any other sensory evidence that a nuclear criticality had taken place.

One area of the roof of Buildings 776 and 777 near the exhaust vent from Booster System No. 1 was 

contaminated with plutonium in the range of 105

 - 106 cpm which corresponded to 0.2 μCi/100 cm2. 

Adjoining ground areas and the exterior of Building 777 were contaminated on the order of 105

 - 106

cpm. The ventilating, electrical, and other utility systems on the second floor of Building 776 were 

similarly contaminated with plutonium. Approximately 8 mCi of plutonium appears to have escaped 

from Buildings 776 and 777 and deposited on the roof or adjoining soil (Voillequé, 1999b). It was 

primarily deposited on the roof of the building and on the ground and one building adjacent to 

Buildings 776 and 777 (ChemRisk 1992). 

The 1965 Glovebox Drain Fire

In 1965, a plutonium fire occurred during a maintenance operation on a plugged glovebox drain in 

Buildings 776 and 777 (see Voillequé 1999c). The fire vented to the room air and spread throughout 

the buildings through the normal ventilation system. About 400 employees, many without respirators, 

were potentially exposed to airborne plutonium dioxide. Body counter measurements indicated that 

25 employees received 1 to 17 times the permissible lung burden. Lung concentrations greater than 

0.008 μCi were found in fifteen employees.

At approximately 10:25 a.m. on Friday, October 15, 1965, a fire occurred during a lathe maintenance 

operation in Room 130 of Building 777. The operation involved unplugging a coolant recirculation line 

for a tape-controlled turning machine. Attempts to remove the obstruction from the glovebox end of 

the line failed; attempts were made to unplug the line through a drain leg near the glovebox. A cap 

was removed from the bottom end of the drain leg and a center punch was inserted to dislodge the 
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obstruction. Sparking was observed when the punch was struck, and a fire resulted, burning the bag 

enclosure for the punch and igniting a plastic and paper pen directly beneath the drain leg.

The fire lasted for one-half to 1-and-a-half minutes and was extinguished with carbon dioxide. It 

vented to the room atmosphere and combustion products were widely spread by the normal 

ventilation pattern. Residues of the fire and a drain leg removed from an adjacent lathe were 

analyzed. The analyses indicated that, during the fire, a chemical reaction occurred between 

plutonium and carbon tetrachloride. The burning of plutonium in air is generally nonviolent and 

described as smoldering. The reaction of plutonium and carbon tetrachloride can be violent.

Fifteen employees had greater than 0.008 μCi of plutonium in their chest counts. Plutonium 

contamination was spread through a major portion of Building 776 and through 25,000 square feet of 

Building 777. Major areas of the buildings were cleaned up by Monday morning, October 18, and 

nearly all production operations resumed at that time (ChemRisk 1992).

The 1974 Control Valve Release

Radioactive particulates escaped from an exhaust stack on the roof of Building 707-A following a 

glovebox atmosphere control valve accident at about 9:53 a.m. on April 2, 1974 (see ChemRisk 

1992). At approximately 1 p.m., Wednesday, April 3, 1974, an elevated count was detected on the 

exhaust stack sample of Inert System No. 2 and Downdraft Plenum No. 4. Results of surveys showed 

the path of contamination movement in the inert system. A flow reversal had apparently occurred 

through the recirculating fans resulting in a release to the environment. 

The accident resulted when the inert atmosphere exhaust valve from the Building 707 storage vault 

was being closed during a glovebox maintenance procedure. This resulted in a pressure surge that 

forced contaminated gas back upstream through the inert gas supply system. The contaminated gas 

was pumped into the atmosphere by the purge exhaust fans through the exhaust stack shared by 

Inert System 2 and Downdraft Plenum 4. This transport of contaminated gas in turn contaminated the 

exhaust ducts. In addition, the pressure surge caused contaminated gas to flow out the open window 

of glovebox 7-K-65, which had been removed for maintenance. This contaminated a nearby module

to levels up to 100,000 counts per minute, and tripped the air monitors. 

Table 2-1 summarizes releases to the environment for several Rocky Flats facility events. 

Table 2-1. Plutonium release estimate distributions by event.

a

Release event

Distribution of estimated release quantity (Ci)

5th percentile 50thpercentile 95th percentile

1957 fire 11 21 36

1969 fire 0.013 0.037 0.062

903 Areab 1.4 3.1 15

a. Modified from Grogan et al. 1999).

b. Releases to air, primarily 1964-1969. Includes particles up to 30 μm AED; 

~20% were estimated to be in the respirable size fraction (<15 μm AED). 

Rocky Flats TBD Section 5 considers particle size conventions and methods 

to convert from one system to another. Work remains to be done in this area 

for the Rocky Flats TBD, and this has been noted in TBD Section 5.

2.6.3

Tritium has been present at Rocky Flats since 1964 as trans-shipments, for “special order” work, as 

standards, in contaminated materials, and as nondestructive testing sources. (ChemRisk, 1992). Two 

measurable releases of tritium occurred at the Rocky Flats Plant (ChemRisk 1992, 1994a, 1995). An 

Tritium at Rocky Flats
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accident in 1968 led to the release of several hundred curies and another in 1973 released 500 to 

2,000 Ci. The 1973 release occurred when tritium-contaminated-material was inadvertently 

processed. An estimated 60 Ci of tritium was released in water effluents, 100 to 500 Ci was retained 

in onsite ponds and tanks, and the remainder escaped to the atmosphere. There were five known 

sources of tritium effluent releases at RFP: Building 779; Building 561; Building 777, which released 

tritium in the 1973 incident; Building 774, where tritium-contaminated water was evaporated; and the 

four solar evaporation ponds adjacent to Building 779. The solar ponds were the source of water fed 

to the Building 774 evaporator (ChemRisk 1992). Figure 2-8 illustrates tritium operations locations. 

2.6.4

Based on information gathered during an extensive investigation of accident records during the Phase 

1 and 2 environmental dose reconstruction project, it is believed that incidents involving uranium at 

RFP have been relatively rare. One exception was associated with the practice of onsite burning of 

wood pallets. In May 1965, three depleted uranium sheets were accidentally burned as a result of 

shipment to RFP from Medina, Ohio, in a package that resembled a nonstandard size wooden pallet. 

Improper labeling and the nonconventional packaging apparently caused the depleted uranium to go 

undetected, and the pallet containing 60 kilograms of slightly radioactive depleted uranium was 

destroyed by burning on May 1, 1965.

Accidents Involving Uranium

Figure 2-9 illustrates the locations of uranium operations on the site.
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REFERENCES

ChemRisk, 1992, Reconstruction of Historical Rocky Flats Operations and Identification of Release 

Points, Project Task 3 & 4 for Phase I, Final Draft Report, prepared for Colorado Department 

of Public Health and Environment, ChemRisk, a Division of McLaren/Hart, Alameda, 

California, August. 

ChemRisk, 1994, Estimating Historical Emissions from Rocky Flats 1952-1989, Project Task 5 for 

Phase I, prepared for Colorado Department of Public Health and Environment, ChemRisk, a 

Division of McLaren/Hart, Alameda, California, March. 

ChemRisk, 1995, Dose Assessment for Historical Contaminant Releases from Rocky Flats, Project 

Task 8 for Phase I, prepared for Colorado Department of Public Health and Environment, 

ChemRisk, a Division of McLaren/Hart, Alameda, California, January.

Grogan, H. A., P. D. McGavran, K. R. Meyer, H. R. Meyer, J. Mohler, A. S. Rood, W. K. Sinclair, P. G. 

Voillequé, J. M. Weber, J. E. Till, 1999, Technical Summary Report for the Historical Public 

Exposures Studies for Rocky Flats Phase II, FINAL, Radiological Assessments Corporation, 

Neeses, South Carolina, September.

Meyer, H. R., S. K. Rope, T. F. Winsor, P. G. Voillequé, K. M. Meyer, L. A. Stetar, J. E. Till, and J. M. 

Weber, 1996, Task 2: The Rocky Flats Plant 903 Area Characterization, RAC Report 2-

CDPHE-RFP-1996-FINAL, Radiological Assessments Corporation, Neeses, South Carolina.

Meyer, K. R., and J. E. Till, 1999, Characterization of Releases to Surface Water From the Rocky 

Flats Plant, RAC Report 7-CDPHE-1996-FINAL (Rev. 1), Radiological Assessments 

Corporation, Neeses, South Carolina, August.

Voillequé, P. G, 1999a, Estimated Airborne Releases of Plutonium During the 1957 Fire in Building 

71, RAC Report 10-CDPHE-RFP-1999-FINAL, Radiological Assessments Corporation, 

Neeses, South Carolina, August.

Voillequé, P. G, 1999b, Estimated Airborne Releases of Plutonium During the 1969 Fire in Buildings 

776-777, RAC Report 9-CDPHE-RFP-1999-FINAL, Radiological Assessments Corporation, 

Neeses, South Carolina, August.

Voillequé, P. G, 1999c, Review of Routine Releases of Plutonium in Airborne Effluents at Rocky Flats, 

RAC Report 6-CDPHE-RFP-1998-FINAL, Radiological Assessments Corporation, Neeses, 

South Carolina, August.

Weber, J. M., A. S. Rood, H. R. Meyer, and J. E. Till, 1999, Development of the Rocky Flats Plant 903 

Area Plutonium Source Term, RAC Report 8-CDPHE-RFP-1998-FINAL (Rev.1), Radiological 

Assessments Corporation, Neeses, South Carolina, August.
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GLOSSARY

alloy

A substance composed of two or more metals blended together.

annual dose equivalent

The dose equivalent received in a year, expressed in units of rem (sievert).

alpha particles

Positively charged particles of discrete energies emitted by certain radioactive materials; alpha 

particles usually expend their energy in short distances and will not usually penetrate the outer 

layer of skin; they are a significant hazard only when taken into the body where their energy Is 

absorbed by tissues.

Atomic Energy Commission

Original agency established for nuclear weapons and power production; a predecessor to the 

U.S. Department of Energy.

beta dose

A designation (i.e., beta) on some external dose records referring to the dose from lessenergetic beta, X-ray and/or gamma radiation (SEE ALSO open window, or shallow dose). 

beta radiation

Radiation consisting of charged particles of very small mass (i.e., the electron) emitted 

spontaneously from the nuclei of certain radioactive elements. Most (if not all) of the direct 

fission products emit beta radiation. Physically, the beta particle is identical to an electron 

moving at high velocity.

curie

A special unit of activity. One curie equals 3.7 x 1010 nuclear transitions per second.

criticality

A self-sustaining nuclear fission reaction.

deep absorbed dose

The absorbed dose at the depth of 1.0 cm in a material of specified geometry and 

composition.

deep dose equivalent (Hd) 

The dose equivalent at the respective depth of 1.0 cm in tissue.

detection limit (lower)

The minimum quantifiable exposure or neutron flux that can be detected.

Delayed neutron analysis (DNA)

Method adopted for both enriched and depleted uranium urinalysis analyses in about 1982.

dose equivalent (H)

The product of the absorbed dose (D), the quality factor (Q), and any other modifying factors. 

The special unit is the rem. When D is expressed in Gy, H is in Sieverts (Sv). 

(1 Sv = 100 rem.)
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dose of record

The dose files provided by DOE to NIOSH as part of the individual worker files. 

dosimeter

A device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual. (SEE albedo dosimeter, film 

dosimeter, neutron film dosimeter, thermoluminescent dosimeter.)

dosimetry

The science of assessing absorbed dose, dose equivalent, effective dose equivalent, etc., 

from external or internal sources of radiation. 

dosimetry system

A system used to assess dose equivalent from external radiation to the whole body, skin, or 

extremities. This includes the fabrication, assignment, and processing of dosimeters as well 

as interpretation and documentation of the results.

exchange period (frequency)

Period (weekly, biweekly, monthly, quarterly, etc.) for routine exchange of dosimeters.

exposure

As used in the technical sense, exposure refers to a measure expressed in roentgens (R) of 

the ionization produced by photons (i.e., gamma and X-rays) in air. 

extremity

That portion of the arm extending from and including the elbow through the fingertips, and that 

portion of the leg extending from and including the knee and patella through the tips of the 

toes.

field calibration

Dosimeter calibration based on radiation types, intensities, and energies in the work 

environment.

film

In general, a "film packet" that contains one or more pieces of film in a light-tight wrapping. 

When developed, the film has an image caused by radiation that can be measured using an 

optical densitometer.

film density

SEE optical density.

film dosimeter

A small packet of film within a holder that attaches to a wearer.

fission

The splitting of a heavy atomic nucleus, accompanied by the release of energy.

fissionable

Material capable of undergoing fission.
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gamma rays

Electromagnetic radiation (photons) originating in atomic. Physically, gamma rays are 

identical to X-rays, the only essential difference being that X-rays do not originate in the 

nucleus. 

HEPA filter

High-efficiency particulate air filter; a dense filter capable of removing a high percentage of 

particulate material from an air flow

HEU

Highly enriched uranium

hydrofluorination

Chemical conversion to a form containing fluorine.

ionizing radiation

Electromagnetic or particulate radiation capable of producing charged particles through 

interactions with matter.

isotope

Elements having the same atomic number but different atomic weights; identical chemically 

but having different physical and nuclear properties

minimum detectable activity (MDA)

Limit of radionuclide activity detection for measurements of specific types and energies of 

radiation

near-net shape

Close to final shape.

neutron

A basic particle that is electrically neutral weighing nearly the same as the hydrogen atom.

neutron, fast

A neutron with energy equal or greater than 10 keV.

neutron, intermediate

A neutron with energy between 0.5 KeV and 10 keV.

neutron, thermal

Strictly, a neutron in thermal equilibrium with surroundings. In general, a neutron with energy 

less than about 0.5 eV.

neutron film dosimeter

A film dosimeter that contains a Neutron Track Emulsion, type A, film packet.

Nuclear Emulsion

Often referred to as “NTA” film and used to measure personnel dose from neutron radiation.

Nuclear Track Emulsion, Type A (NTA)

A film that is sensitive to fast neutrons. The developed image has tracks caused by neutrons 
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that can be seen by using an appropriate imaging capability such as oil immersion and a 

1000X-power microscope or a projection capability.

open window (OW)

Designation on film dosimeter reports that implies the use of little (i.e., only security credential) 

shielding. Commonly used to label the film response corresponding to the open window area. 

operating area

Designation of major onsite operational work areas.

optical density

The quantitative measurement of photographic blackening; density defined as D = Log10 (Io/I).

oralloy

Enriched uranium (containing 0.7 to 93% uranium 235) named for “O”ak “R”idge alloy.

pencil dosimeter

A type of ionization chamber used by personnel to measure radiation dose. The results can 

be labeled as “Pen” doses. Other names include pencil, pocket dosimeter, pocket pencil, 

pocket ionization chamber. 

personal dose equivalent Hp(d)

Represents the dose equivalent in soft tissue below a specified point on the body at an 

appropriate depth (d). The depths selected for personnel dosimetry are 0.07 mm and 10 mm 

for the skin and body, respectively. These are noted as Hp(0.07) and Hp(10), respectively. 

photon

A unit or "particle" of electromagnetic radiation consisting of X- or gamma rays. 

pit

Nuclear weapon core, made of fissionable material.

quality factor, Q

A modifying factor used to derive dose equivalent from absorbed dose.

radiation

Alpha, beta, neutron, and photon radiation. 

radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei.

radionuclide

A radioactive isotope of an element, distinguished by atomic number, atomic weight, and 

energy state

relative biological effectiveness (RBE)

A ratio of the absorbed dose of a reference radiation to the absorbed dose of a test radiation 

producing the same biological effects, other conditions being equal.
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rem

A unit of dose equivalent equal to the product of the number of rad absorbed and the quality 

factor.

rep

Roentgen-equivalent-physical (mrep = millirep) used when reporting beta exposures, usually 

recorded in mrep.

Roentgen (R or r)

A unit of exposure to gamma (or X-ray) radiation. It is defined precisely as the quantity of 

gamma (or X-) rays that will produce a total charge of 2.58 x 10-4 coulomb in 1 kg of dry air. 

An exposure of 1 R is approximately equivalent to an absorbed dose of 1 rad in soft tissue for 

higher (~>100 keV) energy photons.

scrub or salt scrub

shallow absorbed dose (Ds) 

The absorbed dose at a depth of 0.007 cm in a material of specified geometry and 

composition.

shallow dose equivalent (Hs) 

Dose equivalent at a depth of 0.007 cm in tissue.

shielding

Any material or obstruction that absorbs (or attenuates) radiation and thus tends to protect 

personnel or materials from radiation.

sievert (Sv)

The SI unit for dose equivalent. (1 Sv = 100 rem.)

silver shield(s)

The 1-mm thick shields covering the film packet in early personnel film dosimeters. 

site returns

Weapons components that have been retired and returned for disassembly and recovery of 

materials.

skin dose

Absorbed dose at a tissue depth of 7 mg/cm2

. 

thermoluminescence

Property of a material that causes it to emit light as a result of being excited by heat.

thermoluminescent dosimeter (TLD)

A holder containing solid chips of material that when heated will release stored energy as light. 

The measurement of this light provides a measurement of absorbed dose. 

transuranic

An element with an atomic number greater than uranium (92); all transuranic elements are 

radioactive and are produced artificially.
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trigger

Fissionable core of nuclear weapon, used to trigger fusion energy release

whole-body dose

Commonly defined as the absorbed dose at a tissue depth of 1.0 cm (1000 mg/cm2

); however, 

also used to refer to the recorded dose.

X-ray

Ionizing electromagnetic radiation of external nuclear origin.
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ATTACHMENT 2A 

ROCKY FLATS BUILDINGS AND OPERATIONS

Buildings 122 and 122S

1953 Building constructed. Use designated as medical.

Building 218

Building 218 was actually two 10,000-gallon, above-ground, nonradioactive nitric acid storage tanks.

Building 371

Plutonium Recovery Facility

1968 A decision was made to replace the Plutonium Recovery Facility (Building 771) with a 

new building (Building 371).

1972 Construction began on Building 371

1976 Building 371 originally scheduled for startup

1978 Some equipment moved to Building 371

1981 Pilot-scale operations conducted. Due to engineering design problems production 

processes in this building never operated beyond pilot scale. Plutonium recovery 

(electrorefining) operations remained in B-771.

1982-1989 No accidents of any significance occurred in this building. In addition, effluent 

emissions were most likely of little significance to the offsite population because this 

building only ran on a pilot scale basis. Monitoring data for radionuclides were 

available for the life of this building. Emissions data are available for tritium, Pu-238, 

Pu-239/240, Am-241, U-233/234 and U-238 through 1989.

Building 374

Process Waste Treatment Facility

1978 Building brought on-line as the process waste treatment facility for many of the 

production buildings. Emissions data available for tritium, Pu-238, Pu-239/240, Am241, U-233/234, and U-238 through 1991.

1980 Second stage of HEPA filters added.

1986-1988 An increase in waste load.

1988-1989 Condensate from the evaporator went to the cooling tower and was discharged to 

Pond B5. In 1989 this discharge was remedied by not allowing the cooling tower to 

overflow. 

1991 The waste treatment facility was supporting the clean-up of the solar evaporation 

ponds and processing waste for Buildings 122, 123, 443, 444, 460. 559. 707, 774, 

776, 778, 779, 865, 881, 883, and 889. 
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Building 439

Modification Facility

1971 Building constructed. Building 439 houses a machine shop, upholstery shop, battery,

and office space for Building 439/440 support personnel. No radionuclides were known 

to have been handled here.

Building 440

Fabrication Facility

1971 Building constructed. Building 440 was a fabrication facility in which rebuild and rework 

operations to modify and maintain DOE vehicles and rail cars were performed. 

Operations in the building included metalworking, painting, electrical fabrication, and 

assembly. No radioactive material is known to have been present.

Buildings 444, 445, 450, and 455

Depleted Uranium and Beryllium Metallurgy

1953 Building 444 came on line in August, beginning DU processing.

1957 Building 445 added.

1958 Beryllium operations began in Building 444. Blanks received from commercial supplier 

were machined.

1968 Buildings 444 and 445 connected.

1980 Beryllium casting ended.

1981 Production plating laboratory began operations.

1983 Construction of new filter system for Building 444.

1984-1985 New filter system came on-line.

1987 Titanium stripping began.

1989 Uranium foundry shutdown

1990 Production plating lab shut down after a fire

B-450. Date of construction unknown. Building 450 houses the exhaust filter plenum and exhaust 

fans that handle a major portion of the air exhausted from Building 444. The plenum was comprised of 

a demister section and two stages of HEPA filters. Each stage contains 192 HEPA filter units 

mounted 32 units wide by 6 units high. Three exhaust fans pull the exhaust air through the filter 

plenum and discharge the air through vent 200 to the atmosphere. Additional facility 

history/equipment modification details are not available.

B-455. Date of construction unknown. This building was an exterior exhaust filter plenum consisting 

of a demister section and two stages of HEPA filtration. The plenum serves the production plating 

laboratory in Building 444. Each stage contains 16 HEPA filter units mounted 4 units high by 4 units 

wide. The exhaust fan for the plenum exhaust system was mounted on the roof of Building 444. The 

fan discharges through vent 82 to the atmosphere. 
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Foundry. Eight vacuum induction furnaces were used to produce ingots from scrap depleted uranium, 

depleted uranium alloys, silver, aluminum, and copper. Casting processes produce small quantities of 

particulates from mold coating compounds and metal oxidation reactions. All off-gases discharge 

through the Building 44 exhaust system to the Building 450 exhaust filter plenum vent 200. 

Particulate emission control consists of two stages of HEPA filtration.

Mold Cleaning. Graphite molds used in the foundry area in Building 444 for casting ingots were 

manually cleaned using wire brushes and other hand tools. The molds were recycled for reuse. 

Residual material in the mold after ingot removal includes Y2O3, depleted uranium oxide, graphite, 

and trace quantities of iron, silica, and other cast metals. This material was collected and transferred 

by house vacuum to a cyclone collector in the Building 444 Utilities Area. The cyclone was 85 percent 

efficient in removing particles greater than 15 microns. According to plant personnel, approximately 

5% of the material was less than 15 microns. Particulates from mold cleaning discharge through vent 

200 after passing through a vacuum cyclone separator and two stages of HEPA filtration.

Robot Crucible Cleaning. A robot device in Building 444 cleans the graphite crucibles used for 

heating and melting metals in foundry furnaces. The removed residue contains depleted uranium 

oxide with trace amounts of iron, silica Y2O3, graphite, and other cast metals from the crucible. 

Controls consist of the cyclone separator and two stages of HEPA filtration.

Depleted Uranium Machining. Depleted uranium machining operations in Building 444 include 

turning, facing, boring, milling, and sawing using numerically controlled lathes and conventional 

machine tools. Parts were fabricated from depleted uranium, depleted uranium alloy, depleted 

uranium with trace amounts of iron, silica, 71, aluminum, and stainless steel.

Buildings 447, 448 and 451

1956 Building 447 constructed. Manufacturing building for a variety of uranium and Be parts 

either for production or special orders.

1962 Building 448 constructed. Shipping, receiving, and storage building. Handling of 

radioactive materials not indicated in information reviewed.

1983 Construction of a new filter system for Building 447.

B-451. Exhaust Filter Plenum Building serves processes and facilities in Buildings 447 and 448.

Electron Beam Welding. An electron beam welder was used for welding vanadium, beryllium, 

aluminum, depleted uranium, and stainless steel. Welding operations are performed inside a vacuum 

chamber.

Electrochemical Milling Operations (ECM). The ECM machine was used for a variety of production 

and special order jobs. Some work involved milling tungsten, brass, copper, aluminum, and depleted 

uranium.

Vacuum Arc Melt Furnace. The vacuum arc melt furnace was used to melt material for casting 

consumable electrodes in 6-inch and 8-incli diameter copper molds. The metals melted include 

depleted U, and depleted uranium alloy with 6% niobium. The molds may be up to 5 feet long.

Chip Roaster. The chip roaster was used to oxidize depleted uranium scrap metal. The chip roaster 

was a four-tier, single-chamber, vertical roaster.
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Building 460

Consolidated Manufacturing Facility

1984 Building constructed. This building was a non-nuclear facility for war reserve and 

special-order parts and assemblies.

Building 549

1957 Building constructed. This building contains the alarm systems.

1991 This building was used exclusively as an electrical maintenance shop and general 

staging support.

Building 559 and 561

Plutonium Analytical Laboratory

1968 Building Constructed. Plutonium Analytical Lab. The building contains laboratory 

facilities for conducting spectrochemical, chemical, and mass spectrometric analyses.

1973 Building 561 constructed. This building houses the exhaust plenums for Building 559.

Metals, liquids, oxides, oils, and sludges were analyzed for uranium content.

Plutonium Oxidation. Plutonium scraps and oxides remaining after sample analyses were oxidized in 

one of two gloveboxes prior to shipping the PuO2 to another process on the plant. Scrap and oxide 

from all processes were collected in the two gloveboxes, and the oxidation process was run as 

needed (about once a month).

Building 566

Laundry Facility

Construction date unknown. This building was designed as a laundry facility for clothing and 

respirators contaminated with radioactive materials. However, available records related to laundry 

services at the plan do not list Building 566 as a laundry processing facility. We have not resolved this 

discrepancy. 

Building 701

Waste Treatment Research and Development Facility

1965 Building constructed. Pilot Plant Development. Building 701 was a research and 

development facility used to design, build, and evaluate bench-scale and pilot-scale 

waste handling and treatment processes.

Building 705

Coatings Laboratory

1966 Building Constructed. This building includes coatings laboratories and associated 

offices. No evidence of radioactive materials use in Bldg. 705 was found.

– Vapor Deposition

– Beryllium Vapor Deposition

– Parts Cleaning

– Beryllium Parts Cleaning

– Polishing

– Sand Blasting

– Water Cooling
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Building 707

Plutonium Fabrication/Pyrochemical Operations

1972 Construction completed. This building provides metallurgical support in the form of 

foundry and casting operations, as well as product assembly. The machining and 

foundry operations for plutonium came from Building 776 after the 1969 fire.

Plutonium Fabrication/Pyrochemical Operations. This building contains foundry and casting 

operations and products assembly.

Module A - Casting Operations. Carbon tetrachloride was used to clean interior glovebox walls where 

casting furnaces were located in which plutonium ingots were made. 

Module J - Casting Operations. Plutonium ingots were made.

Module K - Casting Operations and Stacker Retriever. This operation stores and retrieves plutonium 

metal for distribution to other processes. Metal was weighed, melted in furnace, and formed into 

ingots.

Module B - Rolling and Forming. This process involves the forming and thermal treatment of 

plutonium metal ingots.

Module C - Briquetting. Metal turnings from Module C machining process and Module B scrap cutters 

were put in metal baskets and dipped in five carbon tetrachloride baths.

Module C - Machining Operations. Plutonium parts were machined.

Modules C and D - Inspection. Parts were cleaned with carbon tetrachloride. 

Casting Operations - Module A. Plutonium ingots were cast into feed or production ingots in Casting 

Operations. Ingots were transported by enclosed, interconnected chain conveyors from storage to the 

foundry gloveboxes. The ingots were placed in crucibles and melted in electric induction furnaces, 

which operate under vacuum. Metal was poured through a funnel into the molds, which were allowed 

to cool. Crucibles and funnels were scraped clean and reused until worn.

Casting Operations - Module J. Two types of particulate emissions result from operations in this 

module. The first was from plutonium oxidation and the second was from casting operations.

Casting Operations and Stacker Retriever - Module K. Module K contains the stacker retriever, also 

known as the X-Y retriever, and casting furnaces. These operations were performed in an inert 

nitrogen atmosphere. The stacker retriever was used to store and retrieve plutonium metal for 

distribution to other processes in Building 707.

Module E, Assembly Operations. Cleaning of plutonium parts.

Module F, Assembly-Superdry. Cleaning of plutonium parts before they were assembled and welded 

into a weapons product.

Module G, Assembly-Welding and Cleaning. Ultrasonic cleaner used to clean plutonium parts 

following welding.
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Module G, Assembly-Electron Bombardment Brazing/ Scanning. Cleaning of waste materials 

deposited on the walls of a bell jar during brazing of metals in the jar

Module H Assembly Testing. Cleaning parts prior to testing.

Modules D, E, and G. Assembly ultrasonic cleaners.

Room 173, Radiography. Cleaning plutonium parts prior to radiography (X-ray examination of parts).

Module D, Weighing. Cleaning prior to weighing of parts.

Module E, Eddy Current Testing. To check the depth of weld penetration on plutonium parts moved 

to and from gloveboxes.

Weld Scanners and Fluorescent Penetrant Operations. Area used to qualify welds on plutonium 

parts.

Module D, Production Control Operations. Cleaning plutonium parts following grit blasting.

Modules D and G, Calibration Laboratory. Cleaning gauges before precision measurements.

Building 771

Plutonium Recovery Operations

1953 Building constructed. The principal operation of Building 771 was the recovery of 

plutonium from plutonium-bearing residues.

1957 Americium line started.

1958 Carbon tetrachloride distilled out of the cutting oil and plutonium recovered from solids. 

The cutting oil, carbon tetrachloride mixture came from plutonium machining in B-776.

1958-1988 Incinerator used for the recovery of fissile material.

1953-1959 Purex process used for plutonium purification.

1959 Began using ion exchange for plutonium purification.

1968 Caustic scrubber installed.

1963-1975 Ammonium thiocyanate used for recovery of americium.

1975-1980s Oxalate precipitation process used for recovery of americium.

Early 1980s Discontinued americium purification but not recovery.

Dissolution. Dissolution processes were all similar in concept. The equipment consisted of a series 

of cascade dissolver vessels. Plutonium bearing material was fed into the first dissolver at a 

controlled rate by a special screw feeder.

Feed Evaporation. Feed evaporation was used to concentrate some solutions from previous 

operations. Concentration of these solutions was necessary to yield precipitation feed of an 

acceptable plutonium concentration.
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Peroxide Precipitation. The peroxide precipitation process converted the plutonium pit in solution to a 

solid form.

Chemical Technology. Plutonium chemistry technology in Building 771 supported and developed 

improved methods for recovering, separating, and purifying actinides from acidic streams.

Calcination. The calcination process converted PuO4 to PuO2 and drove out residual water and 

HNO3, leaving a dry, powdered product. The primary contaminant released from calcination was 

PuO2 particulates.

Hydrofluorination. Plutonium oxide was converted to plutonium tetrafluoride (PuF4) in a continuous 

rotary-tube hydrofluorinator.

Plutonium Oxidation. Plutonium oxidation converted pure plutonium metal, which is pyrophoric, to a 

more stable PuO2. The PuO2 was used as a feed to the dissolution operation.

Plutonium Metallurgy and Research and Air Emissions. The plutonium metallurgy group assisted the 

design agency and plant production in the development of processes that require metallurgical 

production of materials and related techniques. All plutonium metallurgy operations were conducted 

in gloveboxes.

Building 774

Process Waste Treatment Facility

1953 Building constructed to support Building 771. Originally designed as a nuclear waste 

packaging facility. Modifications and additions in 1963, 1965, 1966, 1967, 1970, and 

1974.

1981 Converted to storage for Building 771 (drums).

Radioactive Decontamination Treatment. Nitric acid was used in the first stage of this process. This 

caustic precipitation process reduced plutonium and americium concentrations.

Caustic Precipitation. This process was the first stage in radioactive decontamination treatment. It 

was designed to reduce the plutonium and americium concentrations.

OASIS (organic and sludge immobilization system). TRU waste from 707 and 776/777. TCA, oils 

mixed with carbon tetrachloride were solidified with gypsum cement in a glovebox.

Buildings 776 and 777

Assembly and Manufacturing Buildings

1957 Buildings 776 and 777 constructed. Building 776: Manufacturing building; Building 

777: Assembly Building. Assembly operations transferred from Building 991.

1958 First significant machining of plutonium begins using cutting oil, followed by washing 

with carbon tetrachloride.

1969 Fire in Building 776 on May 11, 1969.

1972 Operations in Building 776 transferred to Building 707. Building 776 converted to 

waste storage and waste size reduction.
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1957-1969 Building 776 was the major user of carbon tetrachloride and TCE at RFP.

B-777. Briquetting. The pressing of plutonium metal machine turnings into pucks using hydraulic 

press. Turnings were cleaned in metal baskets that are dipped into four CCl4 baths.

Machining, Rooms 131 and 134A. Parts were cleaned with CCl4 on towels prior to machining.

Inspection, Rooms 130 and 430. Parts were cleaned with CCl4

Disassembly operations. Disassembly occurred in room 430 and involved the disassembling of 

plutonium parts for further processing in the Molten Salt Extraction (MSE) Operation.

Special Weapons Projects. Special weapons projects perform R&D for fabricating classified parts and 

fitting specialty parts and materials. Plutonium oxidation was conducted to convert pyrophoric 

plutonium residues to non-pyrophoric PuO2. 

Tritium Environmental Control. Tritium was released during the disassembly of some types of 

contaminated parts. The tritium environmental control system removes tritium from gas sampling and 

glovebox exhausts by converting it to tritiated water and desiccating the air stream. Tritium water was 

collected in special containers for further processing.

B-777. Foundry Operations, Coatings. 

– Disassembly Operations, Room 430. Pu parts were disassembled for further processing.

– Assembly Superdry, TCA Wash

– Ultrasonic Cleaning System, Room 430.

– Ultrasonic Cleaning System, Room 440.

– Plutonium Metallography Laboratory. TCA was used as a cutting agent for grinding with 

carbide grit to cut plutonium.

– Special Weapons Projects. R&D for fabricating classified parts and fitting specialty parts and 

materials.

Building 779

Plutonium Development Building

1965 Building constructed. Building 779 was an R&D facility that supported production.

Building 865, 867, and 868

Research and Development of Uranium and Beryllium

1972 Building Constructed. Material and process development

B-867. Date of construction unknown. Contained filter plenums for process exhaust routed from 

Building 865

B-868. Date of construction unknown. Contained filter plenums for process exhaust routed from 

Building 865.
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High Bay. The High Bay area of Building 865 supported production through the research and 

development of metalworking processes. Most work was done with depleted uranium, beryllium, 

copper, tungsten, stainless steel, and other steel alloys. Processes include metal casting, machining, 

rolling, heat-treating, and isostatic: pressing. Chemical etching and cleaning were performed to 

prepare the part for inspection and to remove oily residues, respectively.

Metallography Laboratory. The Metallography Laboratory in Rooms 102, 106, and 108 conducted 

quality control analyses on metal samples. 

High Bay. Production through R&D of metalworking processes.

Grit Blasters, Room 172. Surface cleaning of parts containing depleted uranium.

Building 866

Date of construction unknown. Building 866 was a transfer station. It received wastes from Buildings 

865 and 889 and transferred them to Building 374.

Building 881

1953 Building constructed. Building 881 contained laboratories, maintenance shops, and 

plant support facilities. The original building was designed and built for processing 

enriched uranium. Small quantities of other radioactive materials such as 233uranium 

and plutonium were also handled in the building.

Buildings 883 and 879

Beryllium and Uranium Machining Facility

1957 Building constructed as a rolling and forming (more commonly referred to as 

machining) facility for both enriched and depleted uranium. The building was divided 

into two sides: A side and B side. The A side rolled enriched uranium while the B side 

rolled depleted uranium.

1966 Enriched uranium operations curtailed at Rocky Flats. The A side of Building 883 was 

converted to beryllium rolling (this process was not enclosed). Depleted uranium 

rolling continued on the B side.

Mid-1970s Beryllium machining stopped.

1957-1989 Nitric acid commonly used in a 50:50 water/nitric acid mixture for pickling uranium.

1980-1985 Increased processing of depleted uranium.

Rolling. Metal ingots, including uranium, were rolled in a rolling mill to reduce thickness and establish 

desirable grain structures. 

Shearing. Uranium plates were mechanically cut into smaller pieces before being shaped in other 

mechanical processes. Uranium scrap was recycled by sending it to Building 444 for recasting.

Blanking/Trepanning. Uranium cut from a sheet with a press and die, and desired shapes were cut 

with trepanning tool. Uranium turnings are placed in a drum and sent to Building 447/448 for U chip 

roasting.

Forming. Uranium parts were formed into useful shapes.
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Buildings 886 and 875

Nuclear Safety Facility

1965 Building 886 constructed.

1965--

Present

More than 1,600 criticality experiments were performed. Materials used in the 

experiments (uranyl nitrate metal powder) were re-used. Short-lived fission products 

were produced and none were indicated as having been released to the work or 

outdoor environment. The isotopes decayed rapidly and were contained until stable 

(ChemRisk, 1991).

Building 910 and Solar Ponds 207A, B, AND C

1957 Solar evaporation pond 207A put into use. Used to store and evaporate low level 

contaminated waste containing nitrates and radioactive substances (laundry 

wastewater including plutonium and uranium). The history of the ponds is developed 

further in Rocky Flats TBD Section 4.

1960 Solar Evaporation Ponds 207B and C put into service.

1977 Building 910 (Reverse Osmosis facility) constructed.

Building 991

1951 Construction began on D plant, now known as Building 991. This was the first building 

constructed at Rocky Flats.

1952 Final product assembly operations conducted

1958

1960

Building 777 becomes focal point for assembly operations

Building 991 used for storage and R&D. Emissions data for Bldg 991 include Pu-238, 

Pu-239/240, Am-241, U-233/234, and U-238.

Building 995

Air Handling System

1974 Building constructed. Building 985 houses the air handling system that supports the 

underground storage vaults 996, 997, and 999.

Buildings 990, 990a, 995, 988, 228a, 228b (Listed for completeness – no information is readily 

available concerning whether or not potential for worker exposure existed in these facilities.)

B-990 - Pre-Aeration Building 

B-995 - Sewage Treatment Facility 

B-988 - Tertiary Treatment Pump House
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ATTACHMENT 2B 

ROCKY FLATS JOB TITLES AND DESCRIPTIONS

1. Chemical Operators

Primary job duties included highly enriched uranium (Building 881) and plutonium (Buildings 771 and 

371) metal reprocessing using dissolution, fluorination, calcine, and other wet chemistry methods to 

purify metal in preparation for foundry casting operations. Molten salt processing (Building 776) was 

an exceptionally high neutron process. Other typical job duties included waste treatment (Buildings 

774 and 374) for waste solutions generated on the plant.

2. Metallurgical Operators

Primary job duties included casting (Building 881), rolling, and pressing highly enriched uranium 

(Building 883), plutonium (Buildings 776 and 707) and depleted uranium (Buildings 444, 447, and 

883). Exposures tended to be less than those to Chemical Operators. Machinists, Assemblers, 

Material Analysts and Welders had similar exposures. Non-Destructive Testing (NDT) Technicians 

had similar, but probably lower exposures because work was often done on completed pits that 

inherently shielded the fissile materials. Experimental Operators had similar, but probably higher 

exposures because they often worked with prototype systems or processes that lacked shielding and 

other radiological controls as the regular production processes.

3. Maintenance Workers

Typical trades (i.e., machinists, pipefitters, welders, carpenters, painters, electricians) had varied 

exposures because they often did more intrusive work on contaminated systems than production 

personnel. Examples of intrusive work included repairing leaks on process lines (pipefitters), 

refractory replacement in casting and heat treat furnaces (carpenters), repair of mechanical systems 

(machinists), repair of instruments and controllers inside gloveboxes and other systems (electricians), 

and painting over contamination (painters).

4. Support Personnel

Support personnel included clerk packers, metrology technicians, janitors, and handymen who worked 

in process areas but did little or no hands-on work with radioactive materials. Exposures would be 

incidental to working in rooms with process equipment (metallurgical and chemical operations).

5. Analytical Laboratory Technicians

Analytical laboratory technicians worked primarily in Building 559 (plutonium samples) or 881 (highly 

enriched uranium or depleted uranium samples) and probably had lower exposures than operators 

performing hands on-work with significantly larger radioactive material quantities.

6. Site Support Personnel

Stationary operating engineers (SOEs, also known as boiler vent operators, BVOs), security guards, 

shift managers, and configuration control authority personnel, performed little if any hands-on 

radioactive material or radiation work, but had routine access to process areas. SOEs monitored the 

operation of exhaust systems, waste tanks, and process waste lines. Exposures would be incidental 

to working in rooms with process equipment (metallurgical and chemical operations).

7. Radiation Control Technicians

Radiation Control Technicians (RCTs) probably had exposures from supporting production chemical 

and metallurgical processes. Some significant exposures probably occurred during decontamination 
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activities, surveys of contaminated areas, upset conditions. There was no hands-on work per se, but 

RCTs generally worked side-by-side with production operators.

8. Decontamination & Decommissioning Workers

Decontamination and decommissioning (D&D) work included draining actinide systems, 

decontamination, size reduction and removal of contaminated equipment, gloveboxes, piping, 

ductwork, exhaust systems, waste packaging of removed equipment, low-level and TRU wastes. 

Work was often in high (>2,000 dpm alpha, removable) contamination areas with high air 

concentrations (see RF TBD Section 5 for exposure details. Personal Protective Equipment (PPE) 

included Air Purifying Respirators, Powered Air Purifying Respirators, or PremAir supplied air

systems. There were some high exposures due to direct work with highly radioactive equipment and 

contamination events (See RF TBD Sections 5 and 6 for details).
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ATTACHMENT 2C 

OPERATIONAL ACCIDENTS AND INCIDENTS AT ROCKY FLATS PLANT

Date Location Description (exposure details – see also RF TBD Section 5)

Nov 21, 1952 Not specified Boiler explosion (disruptive force, no known radionuclide involvement) 

June 14, 1957 Not specified Explosion from chemical reaction (3.2 μg Pu lodged in finger)

Sept 11, 1957 Bldg 771, Rm 180 Fire in a manufacturing building; Pu airborne release.

Oct 25, 1961 Not specified Boiler explosion (disruptive force, no known radionuclide involvement)

Apr/June 1962 Not specified Involved internal Pu exposures to three chemical operators

Mar 16, 1963 Not specified Substation failure due to high-velocity winds, and fire (none)

Mar 19, 1963 Not specified Failure of engine in building’s compressor house (none)

Apr 23, 1963 Not specified Contamination from nitric acid spill (none)

June 20, 1963 Not specified Contamination leak and spill in line carrying high-level Pu solution 

(none) 

June 12, 1964 Not specified Chemical explosion in glovebox. Pu lodged in finger, thumb)

Mar 19, 1965 Not specified Glove failed in a glovebox, releasing Pu resulting in measured lung 

deposition, one worker.

Apr 8, 1965 Not specified Inspected parts knocked off shelf (none)

May 6, 1965 Not specified Product feed sprayed out of loose flange, decontamination of three 

workers, details unavailable.

Oct 15, 1965 Bldg 777, Rm 130 Glovebox drain fire releasing Pu resulting in measured lung 

depositions, ten workers

Nov 9, 1965 Not specified Glovebox fire (12 skin decons; no significant internal exposures)

Nov 27, 1965 Not specified Wind damage to building roof (none)

Jan/Mar 1967 Not specified Pu and Am residues accumulated in a fluorinator glovebox and 

required moving. Resulted in 3 worker exposures, details unavailable.

Jan/Mar 1967 Not specified A process operator handled large Pu charges and castings and large 

amounts of material containing 241Am

Apr 5, 1967 Not specified Employee fell from a tractor, broke leg, died 5 days later. No known 

radionuclide exposures.

Apr/June 1967 Not specified Three employees on the Am line, fluorinator, and oxide dissolution. 

Significant exposures (see RF TBD Section 5).

July/Sept 1967 Not specified A DU-Pu-Mo alloy was processed as normal Pu but high gamma 

readings were reported. Details unavailable – 7 external exposures.

Sept 29, 1967 Not specified Contamination spill from blowout of pipe plug. Nuclide data 

unavailable.

Feb 1968 Tritium release of 600 Ci.

1958-68 903 Pad Plutonium-contaminated oil leaked from drums onto outdoor soil

Oct 14, 1968 Not specified An employee inhaled Pu-239 from a fire in a hot waste drum. Details 

unavailable.

Jan 7, 1969 Not specified High wind damage to buildings.

Apr 23, 1969 Not specified Employee showed an unexplained 239Pu lung burden (0.065 μCi)

May 11, 1969 Bldg 776 Glovebox fire in plutonium processing area. See RF TBD Section 5 

for details.

June 20, 1969 Not specified Molten metal released into furnace interior. Details unavailable.

July 30, 1969 Not specified Fire in tunnel between buildings. Details unavailable.

July 30, 1969 Not specified Two chemical operators screened Pu residues that caught fire when 

later stored (inhaled or ingested 0.15 – 0.99 μg) 

Apr 20, 1970 Not specified Contamination release from a plugged drain line. Details unavailable.

Aug 15, 1970 Not specified Power lead short-circuited to bus bar

Sept 11, 1970 Not specified Acid leaked from storage tank

Jan 20, 1971 Not specified A process operator was exposed to 241Am when removing a canned 

Pu button from a shipping container. Lung count noted contamination.
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Attachment 2C (Continued)

Date Location Description (exposure)

Apr 12, 1971 Not specified Corrosion caused steam condensate line to leak contamination. 

Details unavailable.

Apr 19, 1971 Not specified Contamination spread from reduction furnace gasket failure. Details 

unavailable.

June 15, 1971 Not specified A fire started in a shipment of drummed radioactive waste on its way 

to Idaho and self-extinguished (no exposures)

Aug 22, 1971 Not specified Small container exploded and contamination spread by ignited 

plutonium. Measured lung burdens – two employees.

Sept 2, 1971 Not specified Hole in a barrel liner allowed plutonium oxide to escape into room (<4 

μCi)

Jan 5, 1972 Not specified Electrical faulting of three main substations due to winds and snow

Jan 11, 1972 Not specified Cell shrouding of cooling tower blew away

Apr 10, 1972 Not specified Incinerator glovebox fire. Details unavailable.

Feb 8, 1972 Not specified Incinerator fire and contamination caused by a punctured aerosol can 

(no exposures)

Sept 6, 1972 Not specified Three employees exposed to Pu through a faulty glove on a glovebox

Feb 2, 1973 Not specified Supplied air suits contaminated by ignition of a paper filter in the 

compressor Details unavailable.

Apr 1973 Not specified Tritium release of 500 to 2000 Ci to atmosphere and waste streams 

during the processing of metal scrap

Sept 17, 1973 Not specified Elevated levels of tritium were found in Walnut Creek and Great 

Western

Apr 2, 1974 Bldg 707 Control Valve Release due to filter system design error. Details 

unavailable.

Aug 30, 1974 Bldg 777, Rm 452 Tritium release,1.5 Ci

Nov 30, 1975 Not specified Trailer blown over by high winds. Details unavailable.

May 19, 1976 Not specified Contamination of R&D equipment and instruments. Details 

unavailable.

Aug 18, 1976 Not specified Overheating caused coils in induction furnace to melt

Nov 18, 1976 Not specified Source dropped in office area. Details unavailable.

Sources: 

DOE, Rocky Flats Plant Site: Final Environmental Impact Statement, DOE/EIS-0064. April 1980.

AEC, Operational Accidents Within the USAEC 1943-1975, WASH-1192-REV, Fall 1975. Most of the summaries above were 

taken from this document, which was published in late 1975. We have not discovered a similar accident summary for later 

periods, and chose to incorporate this partial listing rather than not.

McLaughlin et al., 2000, A Review of Criticality Accidents, LA-13638, May 2000.
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ATTACHMENT 2D 

FIGURES

Figure 1. Location of the Rocky Flats Plant in Colorado. 
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Figure 2. Rocky Flats facility as it appeared in 1990. 
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Figure 3. Rocky Flats ponds and creeks. 
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Figure 4A. Rocky Flats site waste disposal areas. 
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Figure 4B. Rocky Flats site waste disposal areas. 
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Figure 5. Plutonium air emission sources. 
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Figure 6. Reported gross alpha radioactivity emissions from Rocky Flats plutonium facilities. 
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Figure 7. Sites of major accidents at the Rocky Flats Plant. 
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Figure 8. Tritium air emissions sources. 
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Figure 9. Uranium air emission sources. 
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ATTACHMENT 2E 

PARTIAL LIST OF POTENTIAL HAZARDS ASSOCIATED WITH VARIOUS 

JOB DESCRIPTIONS AND LOCATIONS

Much of the data in the following table is taken from DOE Uranium Mass Balance Project report found at http://tis.eh.doe.gov/

legacy/reports/rockyflats/section1_2.pdf. This table is not a comprehensive listing of potential radiological exposures associated with 

Rocky Flats, but is a summary of data readily available at this time. 

Job title Process description Building Type of work Begin End Material

Primary 

radiation 

type

Maximum 

energy

Analytical laboratory 

technicians

Sample processing 559 Plutonium sample analysis Pu α 5.16 MeV

Analytical laboratory 

technicians

Sample processing 881 HEU or DU sample analysis 1953 1965 HEU α 4.6 MeV

Assemblers Pit Assembly 700 Handled "War Reserve" components

Assemblers Varied - similar to Metallurgical 

Operators depending on location

Varied Handled metal parts

Boiler vent operators (bvos) Varied - depending on location Varied Monitor exhaust systems, waste tanks, 

and process waste lines

Carpenters Varied - depending on location Varied Refractory replacement in casting and 

heat treatment furnaces

Chemical operators Pu metal reprocessing 371 Handled contaminated reagents

Chemical operators Waste treatment 374 Handled contaminated reagents

Chemical operators Waste handling 447 Handled contaminated reagents 1956 1989 DU α 4.2 MeV

Chemical operators Component cleaning 447 Handled contaminated reagents 1956 1989 DU α 4.2 MeV

Chemical operators Waste handling 447 Processed waste materials ?? ?? DU chips α 4.2 MeV

Chemical operators Electrolytic decon of legacy HEU 

contaminated with Pu

707 Handled contaminated reagents 1997 1999 HEU

Pu

α 4.6 MeV

5.6 MeV

Chemical operators Pu metal reprocessing 771 Handled contaminated reagents; Pucontaminated 235U3O8 oxide1965? 1989 Pu235U oxide α 5.16 MeV

4.2 MeV

Chemical operators Waste treatment 774 Handled contaminated reagents, liquid 

wastes from 881

1953 1989 HEU liquid wastes α 4.6 MeV

Chemical operators Molten salt processing 776 Handled contaminated reagents 1958 1969 Pu-239 α 5.16 MeV

Chemical operators Process DU metal 865 Handled contaminated reagents 1953 1989 DU α 4.2 MeV

Chemical operators HEU metal reprocessing 881 Handled contaminated reagents 1953 1965 HEU α 4.6 MeV

Chemical operators Uranyl nitrate processing 886 Handled contaminated reagents

Clerk packers Varied - depending on location Varied Little hands-on work with radioactive 

materials.

Configuration control 

authority personnel

Varied - depending on location Varied Routine access to process areas; little 

hands-on work

Decontamination & 

decommissioning workers

Varied - depending on location 883 Deconned 1993 1995 HEU

DU

α 4.6 MeV

4.2 MeV

Decontamination & 

decommissioning workers

Varied - depending on location 881 B side Deconned 1965 1967 HEU α 4.6 MeV
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Attachment 2E (Continued)

Job title Process description Building Type of work Begin End Material

Primary 

radiation 

type

Maximum 

energy

Decontamination & 

decommissioning workers

Varied - depending on location Varied Drained systems, removed 

contaminated equipment. Often in 

high airborne contamination areas. 

Often wore PPE, including respirators 

with or without supplied air.

Electricians Varied - depending on location Varied Repair of instruments and controllers 

inside gloveboxes and other systems

Experimental operators Varied - depending on location Varied Operated prototype systems, often 

unshielded

Handymen Varied - depending on location Varied Little hands-on work with radioactive 

materials.

Inspection technicians Dimensional Inspection 881 HEU 1953 1965 HEU α 4.6 MeV

Inspectors Testing 444 Inspected completed parts 1953 1994 DU α 4.2 MeV

Janitors Varied - depending on location Varied Little hands-on work with radioactive 

materials.

Machinists Pit Assembly 700 Handled “War Reserve” components

Machinists Machining of Pu parts 776 Operated machining equipment 1958 1969 Pu-239 α 5.16 MeV

Machinists Plutonium assembly 777 Drilling, turning, polishing 1969 Pu-239 α 5.16 MeV

Machinists Process DU metal 865 Machined DU and DU alloys 1953 1989 DU α 4.2 MeV

Machinists 881 Stainless steel boost reservoirs, etc. 1966 1967

Machinists Rod mill grinding 881 Machined HEU parts 1953 1965 HEU α 4.6 MeV

Machinists Rolling, forming, machining 881 HEU 1953 1965 HEU α 4.6 MeV

Machinists Presses, rolling mills 883 - B Operated machining equipment 1957 1965 HEU α 4.6 MeV

Machinists Roll and press DU into sheets 883 - C Rolling mills, shears 1983 1992 DU α 4.2 MeV

Machinists Rolling, forming, machining 883-A Operated machining equipment 1957 1992 DU, DU alloys α 4.2 MeV

Machinists Varied - similar to Metallurgical 

Operators depending on location

Varied Repair of mechanical systems

Material analysts Varied - similar to Metallurgical 

Operators depending on location

Varied Collected metal samples

Metallurgical operators Casting and machining 444 Operated metal handling equipment 1956 1989 DU α 4.2 MeV

Metallurgical operators Casting and machining 444 Operated metal handling equipment 1980 1984 DU α 4.2 MeV

Metallurgical operators Casting and cleaning 444 Operated metal handling equipment 1967 1969 DU/Mo α 4.2 MeV

Metallurgical operators Trim and polish DU sheets 444 Operated metal handling equipment 1953 1989 DU α 4.2 MeV

Metallurgical operators Roll and press DU 447 Operated metal handling equipment 1956 1989 DU α 4.2 MeV

Metallurgical operators Roll and press Pu 707 Operated metal handling equipment Pu-239 α 5.16 MeV

Metallurgical operators Roll and press Pu 776 Operated metal handling equipment 1958 1969 Pu-239 α 5.16 MeV

Metallurgical operators Plutonium assembly 777 1969 Pu-239 α 5.16 MeV

Metallurgical operators Casting, rolling, forming, shearing, 

and cleaning

865 Operated metal handling equipment 1979 1988 DU, DU alloys α 4.2 MeV

Metallurgical operators Casting, extruding, machining 865 Operated metal handling equipment 1979 1988 DU, DU alloys α 4.2 MeV

Metallurgical operators Process DU metal 865 Machined DU and DU alloys 1953 1989 DU α 4.2 MeV

Metallurgical operators Uranium casting 881 Operated metal handling equipment 1953 1965 Uranium α 4.6 MeV

Metallurgical operators Melting and casting 881 HEU 1953 1965 HEU α 4.6 MeV

Metallurgical operators Annealing 883 - B Operated metal handling equipment 1957 1965 HEU α 4.6 MeV

Metallurgical operators Roll and press DU into sheets 883 - C Operated metal handling equipment 1983 1992 DU α 4.2 MeV

Metallurgical operators Roll and press DU 883 A side Operated metal handling equipment DU α 4.2 MeV

Metallurgical operators Roll and press HEU 883 B side Operated metal handling equipment 1953 1964 HEU α 4.6 MeV
Effective Date: 01/10/2004 Revision No. 00 Document No. ORAUT-TKBS-0011-2 Page 58 of 58

Attachment 2E (Continued)

Job title Process description Building Type of work Begin End Material

Primary 

radiation 

type

Maximum 

energy

Metallurgical operators Roll and press Be 883 B side Operated metal handling equipment 1964 ?? Be metal

Metallurgical operators Casting, rolling, forming, shearing, 

and cleaning

883-A Operated metal handling equipment 1957 1992 DU, DU alloys α 4.2 MeV

Metrology technicians Varied - depending on location Varied Little hands-on work with radioactive 

materials.

Non-destructive testing tech Testing 444 Tested parts 1953 1994 DU α 4.2 MeV

Non-destructive testing tech Tensile testing, etc. 447 Tested parts 1956 1989 DU α 4.2 MeV

Non-destructive testing 

technicians

Varied - depending on location 700 Sampled completed pits

Non-destructive testing 

technicians

Casting, extruding, machining 865 Operated metal handling equipment 1979 1988 DU, DU alloys α 4.2 MeV

Non-destructive testing 

technicians

Testing 881 HEU 1953 1965 HEU α 4.6 MeV

Non-destructive testing 

technicians

Varied - depending on location Varied Sampled completed pits

Painters Varied - depending on location Varied Paint over contamination

Pipefitters Varied - depending on location Varied Repair leaks on process lines

Radiation control technicians Varied - depending on location Varied Monitoring in support of chemical and 

metallurgical processes; exposures 

similar to chemical and metallurgical 

operators

Security guards Varied - depending on location Varied Routine security patrols

Shift managers Varied - depending on location Varied Routine access to process areas; little 

hands-on work

Stationary operating 

engineers (SOES)

Varied - depending on location Varied Monitor exhaust systems, waste tanks, 

and process waste lines

Welders Welding 444 Welded parts as necessary 1953 1994 DU α 4.2 MeV

Welders Electron-beam, tungsten-inert gas 

welding

447 Welded parts as necessary 1956 1989 DU α 4.2 MeV

Welders Plutonium assembly 777 Welding, brazing 1969 Pu-239 α 5.16 MeV

Welders Varied - similar to Metallurgical 

Operators depending on location

Varied Welded metal parts