Page 1 of 57

DOE Review Release 08/27/2020

Rocky Flats Plant – Occupational 

Environmental Dose

ORAUT-TKBS-0011-4 Rev. 03

Effective Date: 09/01/2020

Supersedes: Revision 02

Subject Expert(s): Mutty M. Sharfi, Stephen Spanos, David Allen

Document Owner 

Approval: Signature on File

Mutty M. Sharfi, Document Owner

Approval Date: 08/28/2019

Concurrence: Signature on File

Christopher M. Tornes, Objective 1 Representative

Concurrence Date: 08/30/2019

Concurrence: Signature on File

Scott R. Siebert, Objective 3 Manager

Concurrence Date: 08/28/2019

Concurrence: Signature on File

Scott R. Siebert, Project Director Representative

Concurrence Date: 08/28/2019

Approval: Signature on File

Timothy D. Taulbee, Associate Director for Science

Approval Date: 09/16/2019

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.

New Total Rewrite Revision Page Change
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 2 of 57

 

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

01/06/2004 00 New technical basis document for the Rocky Flats Plant –

Occupational Environmental Dose. Incorporates NIOSH and ORAU

formal review comments. First approved issue. Initiated by Robert 

Meyer.

06/29/2004 01 Approved issue of Revision 01. NIOSH material added to 

Introduction; Table 4-1 columns corrected; Table 4-2 values 

corrected; page 50 table list change; Section B.2 3

H dose factor 

discussion added; page 52 table ID changed. Averaged two 1973 Pu 

and Am intake values to provide one annual estimate; changed FEIS 

reference citation on page 8, and corrected reference list for 2 

citations. Incorporates additional NIOSH formal review comments. 

Initiated by Robert Meyer.

04/23/2007 02 Approved Revision 02 initiated to update Section 4.1.1 with standard 

NIOSH text, updated intakes to reflect sitewide maximum intakes 

which required obtaining location-specific model output as opposed 

to location-averaged output. Converted intake units to Bq, changed 

recommended AMAD to 0.3 μm for some years, clarified that 

resuspension was addressed in modeling. Added CDPHE data for 

1999–2005, other clarifications re SC&A comments. Attachment B 

updated to incorporate ICRP 68 organ dose factors. Worker 

Outreach comments pertaining to CT-0202 and CT-0208 have been 

addressed in a revision of Section 4.2.3. Revised to incorporate 

attribution per ORAU direction. Incorporates NIOSH formal review 

comments and an additional comment, changing recommendation of 

0.3 μm to 1.0 μm AMAD for certain years. Constitutes a total rewrite 

of document. This revision results in an increase in assigned dose 

and a PER is required. Training required: As determined by the 

Task Manager. Initiated by Robert Meyer.

09/01/2020 03 Revision initiated to address Advisory Board comments and items 

associated with SEC-00192. Added discussion of Federal Bureau of 

Investigation raid in 1989. Updated internal intakes to be consistent 

with external because the sources of the data are the same. 

Updated onsite ambient values. Deleted Attachment B. Incorporates 

formal internal and NIOSH review comments. Constitutes a total 

rewrite of document. Training required: As determined by the 

Objective Manager. Initiated by Mutty M. Sharfi. 
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TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 5

4.1 Introduction .............................................................................................................................. 7

4.1.1 Purpose........................................................................................................................ 8

4.1.2 Scope........................................................................................................................... 8

4.1.3 Special Exposure Cohort.............................................................................................. 8

4.1.4 Federal Bureau of Investigation (FBI) Raid of RFP in 1989 .......................................... 9

4.2 Internal Dose from Onsite Atmospheric Radionuclide Concentrations.................................... 10

4.2.1 Radionuclides of Concern........................................................................................... 10

4.2.2 Source Terms............................................................................................................. 11

4.2.2.1 Operational Period Source Terms, 1952 to 1992 ......................................... 11

4.2.2.2 Post Operational Period Source Terms, 1993 to 2006 ................................. 12

4.2.3 Annual Intake of Radioactivity..................................................................................... 12

4.3 External Exposure to Onsite Atmospheric Radionuclide Concentrations ................................ 16

4.3.1 Radionuclides of Concern........................................................................................... 16

4.3.2 Exposure Rates.......................................................................................................... 17

4.4 Uncertainty............................................................................................................................. 20

4.4.1 Uncertainty in Internal Exposure Estimates ................................................................ 20

4.4.1.1 Estimated Intakes, 1953 to 1964.................................................................. 20

4.4.1.2 Estimated Intakes, After 1964 ...................................................................... 21

4.4.2 Uncertainties in External Dose Estimate..................................................................... 22

4.5 Attributions and Annotations .................................................................................................. 22

References ........................................................................................................................................ 26

Glossary ............................................................................................................................................ 35

ATTACHMENT A ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS ............................. 37
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LIST OF TABLES

TABLE TITLE PAGE

4-1 Isotopic composition of RFP plutonium .................................................................................. 11

4-2 Sitewide maximum annual median inhalation intakes of 239/240Pu and 241Am based on 

atmospheric modeling, 1953 to 1964 ..................................................................................... 13

4-3 Sitewide maximum annual median inhalation intakes of 239/240Pu and 241Am based on 

monitoring data, 1965 to 2005................................................................................................ 15

4-4 External gamma radiation ...................................................................................................... 19

A-1 Monthly average concentrations of TLLα activity in onsite air samples, October 1964 to 

December 1971 .....................................................................................................................51

A-2 Estimated annual average concentrations of 239/240Pu in onsite air samples, 1965 to 2005 ..... 53

A-3 Annual average concentrations of plutonium in air for three location groups, contractor 

monitoring, 1971 to 1990........................................................................................................ 54

A-4 Comparison of 239/240Pu concentrations in onsite and offsite air as measured by CDPHE....... 55

A-5 Annual average concentrations of 239/240Pu in Denver air, 1971 to 1989 ................................. 56

A-6 Corrected annual average concentrations of 239/240Pu in air at perimeter monitoring 

stations ..................................................................................................................................57

LIST OF FIGURES

FIGURE TITLE PAGE

4-1 Grid map used in atmospheric modeling, showing locations of six computational nodes 

representing the industrial area.............................................................................................. 14

4-2 External dose as a function of year ........................................................................................ 18

A-1 Location of samplers operated by contractor.......................................................................... 44

A-2 Location of computational nodes used to predict average air concentrations for industrial 

area .......................................................................................................................................45

A-3 Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in industrial area ............................................................................................................46

A-4 Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in the perimeter area...................................................................................................... 47

A-5 Locations of computational nodes used to compute annual average perimeter 

concentrations shown in Figure A-6 ....................................................................................... 48

A-6 Eastern part of industrial area, showing locations of CDPHE air monitoring stations D-1 

to D-5 .....................................................................................................................................49

A-7 Locations of offsite air samplers in 1975 ................................................................................ 50
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ACRONYMS AND ABBREVIATIONS

AED aerodynamic equivalent diameter

AMAD activity median aerodynamic diameter

AWE atomic weapons employer

Bq becquerel

CDPHE Colorado Department of Public Health and Environment

Ci curie

CL confidence limit

cm centimeter

DOE U.S. Department of Energy

DOL U.S. Department of Labor

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

EPA U.S. Environmental Protection Agency

fCi femtocurie

FEIS final environmental impact statement

FGR Federal Guidance Report

ft foot

g gram

GM geometric mean

HEPA high-energy particulate air

hr hour

ICRP International Commission on Radiological Protection

ID identification

km kilometer

m meter

mCi millicurie

mi mile

mrem millirem

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

PER Program Evaluation Report

RATCHET Regional Atmospheric Transport Code for Hanford Environmental Tracking

RFETS Rocky Flats Environmental Technology Site

RFP Rocky Flats Plant

s second

SC&A S. Cohen & Associates

SEC Special Exposure Cohort

SRDB Ref ID Site Research Database Reference Identification (number)
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Sv sievert

TBD technical basis document

TLD thermoluminescent dosimeter

TLLα total long-lived alpha

U.S.C. United States Code

yr year

χ/Q maximum predicted normalized air concentration

μCi microcurie

μm micrometer

μrem microrem

§ section or sections
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4.1 INTRODUCTION

Technical basis documents and site profile documents are not official determinations made by the 

National Institute for Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historical background information and guidance to assist in the preparation of 

dose reconstructions at particular Department of Energy (DOE) or Atomic Weapons Employer (AWE) 

facilities or categories of DOE or AWE facilities. They will be revised in the event additional relevant 

information is obtained about the affected DOE or AWE facility(ies). These documents may be used 

to assist NIOSH staff in the evaluation of Special Exposure Cohort (SEC) petitions and the completion 

of the individual work required for each dose reconstruction.

In this document the word “facility” is used to refer to an area, building, or group of buildings that 

served a specific purpose at a DOE or AWE facility. It does not mean nor should it be equated to an 

“AWE facility” or a “DOE facility.” The terms AWE and DOE facility are defined in sections 7384l(5) 

and (12) of the Energy Employees Occupational Illness Compensation Program Act of 2000 

(EEOICPA), respectively. An AWE facility means “a facility, owned by an atomic weapons employer, 

that is or was used to process or produce, for use by the United States, material that emitted radiation 

and was used in the production of an atomic weapon, excluding uranium mining or milling.” 42 U.S.C. 

§ 7384l(5). On the other hand, a DOE facility is defined as “any building, structure, or premise, 

including the grounds upon which such building, structure, or premise is located ... in which 

operations are, or have been, conducted by, or on behalf of, the [DOE] (except for buildings, 

structures, premises, grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program);” 

and with regard to which DOE has or had a proprietary interest, or “entered into a contract with an 

entity to provide management and operation, management and integration, environmental 

remediation services, construction, or maintenance services.” 42 U.S.C. § 7384l(12). The Department 

of Energy (DOE) determines whether a site meets the statutory definition of an AWE facility and the 

Department of Labor (DOL) determines if a site is a DOE facility and, if it is, designates it as such.

Accordingly, a Part B claim for benefits must be based on an energy employee’s eligible employment 

and occupational radiation exposure at a DOE or AWE facility during the facility’s designated time 

period and location (i.e., covered employee). After DOL determines that a claim meets the eligibility 

requirements under EEOICPA, DOL transmits the claim to NIOSH for a dose reconstruction. 

EEOICPA provides, among other things, guidance on eligible employment and the types of radiation 

exposure to be included in an individual dose reconstruction. Under EEOICPA, eligible employment 

at a DOE facility includes individuals who are or were employed by DOE and its predecessor 

agencies, as well as their contractors and subcontractors at the facility. Unlike the abovementioned 

statutory provisions on DOE facility definitions that contain specific descriptions or exclusions on 

facility designation, the statutory provision governing types of exposure to be included in dose 

reconstructions for DOE covered employees only requires that such exposures be incurred in the 

performance of duty. As such, NIOSH broadly construes radiation exposures incurred in the 

performance of duty to include all radiation exposures received as a condition of employment at 

covered DOE facilities in its dose reconstructions for covered employees. For covered employees at 

DOE facilities, individual dose reconstructions may also include radiation exposures related to the 

Naval Nuclear Propulsion Program at DOE facilities, if applicable. No efforts are made to determine 

the eligibility of any fraction of total measured exposure for inclusion in dose reconstruction.

NIOSH does not consider the following types of exposure as those incurred in the performance of 

duty as a condition of employment at a DOE facility. Therefore these exposures are not included in 

dose reconstructions for covered employees (NIOSH 2010):

• Background radiation, including radiation from naturally occurring radon present in 

conventional structures

• Radiation from X-rays received in the diagnosis of injuries or illnesses or for therapeutic 

reasons
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4.1.1 Purpose

The preparation of this technical basis document (TBD) used available information about the Rocky 

Flats Plant (RFP) environment dating back to 1952. 

Occupational environmental dose is the radiation dose received in the course of work duties outside 

Plant buildings but on the RFP site. Internal and external exposures to radionuclides in the outdoor 

environment are considered separately here in calculating this dose. Estimated occupational 

environmental dose can be used when a worker did not have the potential for routine exposures.

4.1.2 Scope

Section 4.2 presents information necessary to estimate internal environmental dose. It identifies the 

radionuclides of concern. Development of the list of radionuclides relied on work done for the 

Historical Public Exposure Studies on Rocky Flats (ChemRisk 1994a; Rood, Grogan, and Till 1999). 

Section 4.2 discusses the resulting source terms (release rates) for radionuclides considered 

potentially significant to internal environmental dose and provides estimated annual inhalation intake 

activities of radionuclides.

Section 4.3 contains information necessary for estimating external environmental dose. Ambient 

doses, taken from annual environmental reports for RFP, were developed for the site. The reports 

summarize external dose at the Plant, its general environs, and selected nearby communities. 

Section 4.4 considers uncertainties in the information provided for estimating occupational 

environmental dose. The discussion addresses sources of uncertainty and provides quantitative 

information where possible. 

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 4.5. 

4.1.3 Special Exposure Cohort

The Secretary of the U.S. Department of Health and Human Services has designated the following 

class of employees for addition to the SEC (Sebelius 2013): 

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors who worked at the Rocky Flats Plant in Golden, 

Colorado, from April 1, 1952 through December 31, 1983, for a number of work days 

aggregating at least 250 work days, occurring either solely under this employment or in 

combination with work days within the parameters established for one or more other 

classes of employees included in the Special Exposure Cohort.

NIOSH determined that doses to unmonitored RFP workers from neptunium, thorium, and 233U (and 

its associated 232U and 228Th progeny) cannot be reconstructed from April 1, 1952, through 

December 31, 1983. The class includes all workers during the SEC period. Because of the identified 

dose reconstruction infeasibility, all dose reconstructions for monitored workers during the SEC period 

are considered partial dose reconstructions. If monitoring data are available for workers in the SEC, 

dose is to be assigned as appropriate based on that data. However, such dose reconstructions are 

still considered partial dose reconstructions because of the determination that exposure to neptunium, 

thorium, and 233U (and its associated 232U and 228Th progeny) during the SEC period cannot be 

bounded (NIOSH 2013). In addition, reconstruction of unmonitored neutron doses before 1967 has 

been identified as infeasible and therefore cannot be bounded. It is not feasible to reconstruct 
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unmonitored neutron doses, in a bounding manner, before 1967. Therefore, this TBD does not 

provide dose reconstruction guidance for unmonitored neutron doses before 1967. 

4.1.4 Federal Bureau of Investigation (FBI) Raid of RFP in 1989

On October 24 and 25, 1989, a former RFP worker made allegations in a set of interviews with the 

U.S. Environmental Protection Agency’s National Enforcement Investigation Center’s Office of

Criminal Investigations and the FBI. The interviews resulted from a telephone call by the interviewee 

to the FBI Rocky Flats Hotline on June 16, 1989, alleging safety violations and manipulation of

laboratory samples at RFP.

Attachment I of ORAUT-TKBS-0011-5, Rocky Flats Plant – Occupational Internal Dose, provides a 

detailed assessment of these allegations (ORAUT 2020). The following is a summary of the 

conclusions of this assessment:

• No scientific basis for concluding that the issues raised about environmental samples would

compromise radiological count results, and the reviewed information does not corroborate a

link between the environmental and occupational radiological programs.

• There were no identified situations in which falsification or invalidation of data would affect the

ability to perform dose reconstruction under EEOICPA.

• The charges against Rockwell were specific to the impact to the environment under

environmental laws such as the Resource Conservation and Recovery Act of 1980 and the

Clean Water Act; the charges did not specifically call out a data falsification, data validity

issues, or a data quality violation.

• One worker provided information about personal involvement in shredding documents. While

those documents could have been some kind of field surveys, there is no indication that those

surveys have an effect on the ability to bound or reconstruct dose for the class, as long as

adequate personnel monitoring data exist. These records do appear in the associated files

and are available to the Project.

• An issue of “penciling-in” information on radiological field survey records was raised. The

primary source of radiological information for individual dose reconstruction is the individual

TLD dosimetry and bioassay information. These are performed in a laboratory and not

documented in the field.

• Concerns about bioassay sample analysis results (false positives and statistical variations);

bioassay sample handling and processing; personnel contamination and contamination

incidents; and issues related to tritium bubblers, neptunium, Mg-Th alloy, and the Criticality

Laboratory. The dose reconstruction process accounts for the potential for missed doses and

incorporates methods that are favorable to claimants. All of the issues in relation to tritium

bubblers, neptunium, Mg-Th, and the Criticality Laboratory are addressed in other sections of

this TBD.

• A contention was made that there was an additional August 1989 aerial Multispectral Scanner

Survey (MSS) at RFP in addition to one in June and July of 1989, and that the flyover data

indicate the presence of the isotopes 137Cs and 90Sr, which was used to imply that an

unreported criticality occurred. No evidence of either a second flyover in August 1989 or

evidence supporting a criticality event could be found in the available RFP records. Based on

interviews, document reviews, and other files, no evidence or information was identified that

disputes the ability to bound RFP worker dose under the EEOICPA program.
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• A review of the RFP Technical Safety Appraisal concluded that there was no identified effect 

on the radiological personnel monitoring data NIOSH uses to support bounding or 

reconstruction of dose for RFP workers. 

• A review of an allegation of record falsification involving mislabeling waste for shipment off site 

concluded that none of this information affects the ability to reconstruct radiation dose with 

sufficient accuracy.

• A review of excerpts from the notebooks of an RFP manager who made notes on the 

radiological program did not support a data falsification issue that would affect the ability to 

reconstruct dose for RFP workers. 

• The ORAU Team conducted a review of the quantity of available personnel radiological 

monitoring data for this assessment. It concluded that sufficient individual monitoring data 

exist to support the assessment of worker doses. 

• A review of the Colorado Federal District Court Report of the Federal District Special Grand 

Jury (Unknown 1992) indicates that RFP had a number of violations. These included a 

deficient ground-water monitoring system, failure to notify government agencies of 

environmental law violations, storage issues, and chemical violations. However, the grand jury 

review of the FBI’s findings did not identify any deficiencies with the radiological monitoring 

programs (i.e., no deficiencies are assumed to exist with the external ambient data and/or 

environmental air data). 

Based on this information, the ORAU Team concluded this information has no effect on its ability to 

perform onsite ambient or environmental dose reconstructions with sufficient accuracy.

4.2 INTERNAL DOSE FROM ONSITE ATMOSPHERIC RADIONUCLIDE CONCENTRATIONS

4.2.1 Radionuclides of Concern

The Historical Public Exposures Studies on Rocky Flats were conducted in the 1990s as part of a 

1989 Agreement in Principle between DOE and the State of Colorado to identify potential health 

effects in nearby communities exposed to past releases. Phase I and Phase II of the studies provided 

comprehensive analyses of releases of radionuclides from RFP from 1953 to 1989, although 

component assembly operations actually began in 1952 and all production operations formally ceased 

in 1992 (ChemRisk 1992, 1994a; Voillequé and Till 1999a, 1999b, 1999c; Weber et al. 1999). 

The Phase I study identified several radionuclides as potentially significant releases: 3

H, natural 

thorium, enriched and depleted uranium, 239/240Pu, 241Pu, and 241Am. The results of the Phase I study 

identified plutonium as the primary material of concern in relation to offsite exposures. The Phase II 

study focused the air pathway exposure assessment on the isotopes of plutonium. The potential 

importance of 3

H, enriched and depleted uranium, and 241Am to onsite exposures was reevaluated 

here to determine if previous determinations of insignificance were relevant for occupational 

exposures. Releases of natural thorium were difficult to quantify, but were probably insignificant 

based on a review of processes and ventilation filter use (ChemRisk 1994a, p. 135).

To evaluate the potential significance of radionuclides other than isotopes of plutonium, an estimate 

was developed of committed inhalation dose from a 1-yr intake using airborne stack emission 

estimates from the Phase I study, the air dispersion modeling results from Phase II, an assumed 

inhalation rate of 3,000 m3

/yr (2,500 hr/yr × 1.2 m3/hr; breathing rate is based on guidance in ICRP 

(1994) Publication 66). Attachment A contains a summary of the atmospheric dispersion model. 

Briefly, the maximum organ dose due to inhalation [assuming an activity median aerodynamic 
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diameter (AMAD) of 0.3 μm] in any given year since 1953 for any of these radionuclides was 

estimated to be that for 241Am, on the order of 34 mrem for the stack releases. The maximum 

predicted committed doses for 3

H, depleted uranium, and enriched uranium for a 1-yr intake were 

0.06 mrem, 1.2 mrem, and 0.65 mrem, respectively. The Phase I study estimated that 241Am was

potentially present in excess of 0.23 times the alpha activity of 239/240Pu in the 903 Area due to 

ingrowth of 241Am from 241Pu in the cutting oil stored in that area and in soils contaminated with the 

cutting oil (ChemRisk 1994b, Appendix H). Therefore, 241Am associated with soil resuspended from 

the 903 Area or emitted with plutonium isotopes from stacks was considered a contributor to dose. 

Stack releases of 3

H and the uranium isotopes were excluded as potentially significant contributors.

The Final Environmental Impact Statement for the Rocky Flats Plant, Golden, Jefferson County, 

Colorado (DOE 1980) indicates an isotopic composition of plutonium by weight as follows:

Table 4-1. Isotopic composition of RFP 

plutonium.

Isotope

Percent 

by weighta

Percent of Pu 

alpha activity

Pu-238 0.01 2.34

Pu-239 93.79 79.78

Pu-240 5.80 17.88

Pu-241 0.36 (beta emitter)

Pu-242 0.03 0.00165

a. Source: DOE (1980, Table 2.7.2-2). 

As indicated in the table, 238Pu and 242Pu are minor contributors to the alpha activity of plutonium 

expected in the RFP environment [1]. Therefore, the following sections report source terms and 

intakes only for 239/240Pu and 241Am.

4.2.2 Source Terms

The evaluation of atmospheric source terms for 239/240Pu and 241Am that were released to the RFP 

environment addresses two periods: the operational period from 1952 to 1992 when production

activities were ongoing and the post-operational period (1993 to 2006), when production activities had 

ceased and releases were more likely to occur as a result of past contamination or decontamination 

and decommissioning activities.

4.2.2.1 Operational Period Source Terms, 1952 to 1992

In 1952, the only operational activities at RFP were in Building 991 (Putzier 1982), in which 

components manufactured at other locations were assembled (ChemRisk 1992). No significant 

emissions were estimated to have occurred during this year. From 1953 through part of 1992, 

fabrication and recycling activities at RFP resulted in radionuclide releases to the onsite atmospheric 

environment as a result of “routine” operations (continuous releases), and “non-routine incidents” 

(discrete events). The term “routine” was used in the Radiological Assessments Corporation Phase II 

dose reconstruction reports to distinguish continuous releases from the release spikes that occurred 

during the 1957 and 1969 fires and during 903 Area high-wind events. However, routine releases 

“included discharges that were due to a variety of unplanned events and conditions that arose during 

facility operations,” including “small fires involving plutonium metal,” the “peroxide tank explosion in 

Building 771 in 1957, and the glovebox drain fire in Building 776 in 1965,” among other events 

(Voillequé and Till 1999c).

The most significant discrete release occurred during and shortly after September 11, 1957. A 

glovebox fire in Building 71 (also known as Building 771) resulted in a release of plutonium estimated 

at 21 Ci (50th-percentile estimate; Voillequé and Till 1999a). The next most significant discrete 
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release location was the 903 Drum Storage Area (also called the 903 Pad or 903 Area). An estimated 

3.1 Ci (50th percentile) of plutonium (<30-μm size fraction) were released from the 903 Pad over 

several years, mainly as a result of mechanical disturbance and wind action (Weber et al. 1999). This 

estimate consists of the 24-hr integrated release quantities for 24 identified discrete events from 1964

to 1969. An asphalt pad placed over the area in 1970 decreased the source term dramatically, 

although resuspension of downwind contaminated soil continued to disperse plutonium to the air in 

later years. The third most significant non-routine contaminant release occurred during the May 11, 

1969, fire, when approximately 0.037 Ci (37 mCi) of plutonium was released from the Building 779 

stack (Voillequé and Till 1999b). 

Total routine (nondiscrete) plutonium emissions from 1953 to 1989 are estimated to be on the order of 

0.12 Ci (Voillequé and Till 1999c). This estimate does not include releases due to resuspension of 

contaminated soil downwind of the 903 Pad or resuspension of contaminated soil in other areas of the 

Plant due to deposition from the primary sources. Although the release of plutonium due to 

resuspension is not included in this estimate of routine emissions, it is addressed in this TBD as a 

contributor to exposure.

4.2.2.2 Post Operational Period Source Terms, 1993 to 2006

After 1992, production operations at RFP officially ceased. However, releases of plutonium to the 

environment could still occur due to contaminated soils. Average and maximum annual median 

ambient concentrations, provided in Table A-2 (Attachment A), are consistent and do not appear to 

have increased since operations ceased. 

4.2.3 Annual Intake of Radioactivity

To calculate intakes of 239/240Pu and 241Am, the estimated sitewide maximum annual median [2] air 

concentrations of these isotopes in the RFP environment were multiplied by an annual inhalation rate. 

The assumed breathing rate was 3,000 m3

/yr, corresponding to an hourly rate for light activity of 1.2 

m3 (based on ICRP Publication 66; 1994), and a 2,500-hr work year. Intake rates should be scaled to 

account for occupancy times other than 2,500 hr of exposure.

Air concentrations of 239/240Pu and 241Am were estimated as described in Attachment A. Onsite air 

monitoring data are the preferred source of air concentrations (see Attachment A) for 239/240Pu, but in

the early years (until 1964) such data were not sufficiently descriptive or complete to allow reliable 

estimates. Therefore, dispersion modeling results were used to estimate air concentrations of 

239/240Pu for these years. During these early years, stack or building vent emissions were the main 

source of plutonium to onsite air, and measurements of these releases are available. Resuspension 

of previously deposited isotopes also contributed to onsite air concentrations. The model for this 

analysis (described in Attachment A) addressed contributions from the primary sources in the Phase I 

study (ChemRisk 1992, 1994a) as well as resuspension. The ratios of 241Am activity to 239/240Pu 

activity in effluents were not measured until the 1980s; however, between 1985 and 1989, this ratio 

averaged 0.22 (ChemRisk 1994a). This ratio likely overestimates the fractional release in earlier 

years, when less 241Am had grown in to the plutonium available for processing Therefore, the use of 

this ratio to estimate 241Am concentrations from 1953 to 1964 is considered a favorable assumption. 

After 1964, suspension or resuspension (Rood, Grogan, and Till 1999, p. 72) of contaminated soil was 

the main source of plutonium releases to onsite air. Air monitoring data provided either total longlived alpha (TLLα) concentrations, from which 239/240Pu values could be derived, or actual 

measurements of 239/240Pu. The annual environmental reports (see the Environmental Reports section 

of the References) were useful in providing summaries of air concentrations by sampler location 

based on monthly reporting through 1994. After 1994, Rocky Flats Environmental Technology Site 

(RFETS) monitoring reports and the CDPHE monitoring reports provided quarterly summaries of 
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monitoring results. Activity concentrations of 241Am were estimated after 1964 by assuming that the 

concentration of 241Am was 30% of the 239/240Pu concentration based on measurements of the

241Am/239Pu activity in RFP soil by three separate researchers (Poet and Martell 1972; Krey et al. 

1976; Litaor and Allen 1996). This assumption is favorable to claimants because the average 

measured activity ratios in soil were found to be less than 0.20 by these three groups of researchers 

[3]. 

Table 4-2 lists estimated annual intakes of 239/240Pu and 241Am from 1953 to 1964, based on the 

atmospheric modeling described in Attachment A. The values are expressed in becquerels per year. 

The calculated intakes represent a maximum annual median (50th percentile) of the six computational 

nodes evaluated in the RFP industrial area for 500 Monte Carlo model realizations simulated for each 

year, and are exclusive of the buffer zone (Figure 4-1). The location of the maximum concentrations 

was the north-central, northeast, or southeast node, which was expected based on the locations of 

the primary sources and the general west-to-east wind direction. The median intakes in Table 4-2 

correspond to isotopes associated with particles smaller than 15-μm aerodynamic equivalent diameter 

(AED), which is an upper limit for respirable particles according to Rood, Grogan, and Till (1999, p. 6) 

[4]. 

Table 4-2. Sitewide maximum annual median 

inhalation intakes (Bq/yr) of 239/240Pu and 241Am 

based on atmospheric modeling, 1953 to 1964

(AED <15 μm; assume respirable).a 

Year Pu-239/240 Am-241b

1953 4.50E−05 9.75E−06

1954 2.13E−04 4.63E−05

1955 2.13E−04 4.50E−05

1956 6.88E−04 1.50E−04

1957 8.50E−02 1.88E−02

1957 w/o fire 2.63E−02 5.88E−03

1958 1.14E−02 2.50E−03

1959 1.01E−02 2.25E−03

1960 6.25E−03 1.38E−03

1961 3.63E−03 8.00E−04

1962 6.75E−03 1.50E−03

1963 1.75E−02 3.75E−03

1964 7.63E−02 1.63E−02

a. Atmospheric modeling described in Attachment A.

b. Am-241 intake is assumed to be 22% of the Pu-239/240 

intake (Section 4.2.3). 

Table 4-2 lists two results for 1957. Results for “1957” include the September 11 fire, which caused 

the annual intakes to be substantially higher than during the years before and after. If a worker was 

known to have been present during that year, and that individual might have been present in 

September, it is appropriate to use this value. The results for “1957, w/o fire” should be used for 

individuals who worked a partial year that did not include the month of September. Elevated releases 

of 239/240Pu and 241Am attributable to the 1957 fire occurred over several hours after the fire began at 

approximately 10:00 p.m. on September 11. Exposure to the direct releases would have occurred 

during that month (the air concentrations associated with soil-deposited 239/240Pu from the fire are

included in both 1957 values by considering resuspension of contaminated soil in the dispersion 

modeling). 

Table 4-3 lists estimated annual intakes of 239/240Pu and 241Am between 1965 and 2005. The values 

for 239/240Pu in this table are based on sitewide maximum annual median measured concentrations at 

samplers across the site, and therefore represent concentrations at the locations of higher 
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Figure 4-1. Grid map used in atmospheric modeling, showing locations of six computational nodes 

representing the industrial area. 

479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area

concentration (typically near the 903 Area). Therefore, these values are inherently favorable to 

claimants when applied as an estimate of environmental exposure for the industrial area. The 

239/240Pu air concentrations supporting the intakes in Table 4-3 are described in Attachment A and 

summarized in Table A-2. Intake rates were calculated from air concentrations by assuming a 

respirable fraction of 1.0, despite the reported values of this parameter ranging from 0.2 to 0.4 in a 

review of the subject in Rope et al. (1999, pp. 144–146). Low- and high-volume air samplers at RFP 

collected particles larger than respirable (Rope et al. 1999) to varying degrees as samplers were 

replaced over the years. Because the respirable fraction of sampled particles is not accurately 

known, a respirable fraction of 1.0, which is favorable to claimants, was assumed. 

The values reported for 241Am in Table 4-3 (after 1970) were calculated by multiplying the 239/240Pu 

intake values by 0.30, in accordance with the rationale described previously. Again, a respirable 

fraction of 1.0, which is favorable to claimants, was assumed.

Annual intakes estimated in Tables 4-2 and 4-3 are based on a 3,000-m3

/yr (2,500 hr/yr × 1.2 m3/hr; 

breathing rate, based on guidance in ICRP Publication 66 inhalation rate (ICRP 1994), but can be 

scaled to account for different occupancy times. Furthermore, the values can be scaled for partial

year exposures, with the following cautionary note. For 1957, approximately 70% of the intake of 

239/240Pu can be attributed to the September 11 fire. Therefore, if a worker was present on the site for 

only a portion of 1957, but during September, the entire annual intake should be assumed. If a 
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worker was present on the site in 1957, but not during September, the intake designated “1957 w/o 

fire” should be assumed, and scaling of this value for a partial year exposure can be done.

Table 4-3. Sitewide maximum annual median inhalation intakes (Bq/yr) of 239/240Pu and 241Am based 

on monitoring data, 1965 to 2005 (respirable fraction of sampled particles = 1.0). 

Year Pu-239/240a Am-241b

1965 2.22E−01 6.66E−02

1966 4.44E−01 1.33E−01

1967 1.33E+00 4.00E−01

1968 4.22E+00 1.27E+00

1969 7.44E+00 2.23E+00

1970 3.33E−01 9.99E−02

1971 4.44E−01 1.33E−01

1972 4.33E−01 1.30E−01

1973 7.22E−01 2.16E−01

1974 3.55E−01 1.07E−01

1975 1.11E−01 3.33E−02

1976 1.55E−01 4.66E−02

1977 6.66E−02 2.00E−02

1978 9.99E−02 3.00E−02

1979 5.55E−02 1.67E−02

1980 5.55E−02 1.67E−02

1981 5.55E−02 1.67E−02

1982 5.55E−02 1.67E−02

1983 4.44E−02 1.33E−02

1984 6.66E−02 2.00E−02

1985 4.44E−02 1.33E−02

Year Pu-239/240a Am-241b

1986 5.55E−02 1.67E−02

1987 1.33E−01 4.00E−02

1988 7.77E−02 2.33E−02

1989 5.55E−02 1.67E−02

1990 9.99E−02 3.00E−02

1991 1.33E−01 4.00E−02

1992 6.66E−02 2.00E−02

1993 4.44E−02 1.33E−02

1994 4.44E−02 1.33E−02

1995 2.22E−02 6.66E−03

1996 8.88E−03 2.66E−03

1997 7.77E−03 2.33E−03

1998 1.11E−02 3.33E−03

1999 1.11E−02 3.33E−03

2000 1.11E−02 3.33E−03

2001 2.22E−02 6.66E−03

2002 5.55E−03 1.67E−03

2003 2.22E−02 6.66E−03

2004 3.33E−03 9.99E−04

2005 1.11E−02 3.33E−03

a. Calculated from maximum air concentration data in Table A-2.

b. Calculated by multiplying Pu-239/240 intake by 0.30 (see Section 4.2.3). 

The assumed solubility of inhaled 239/240Pu should consider the following information. Plutonium in 

metal-working operations and involved in fires is generally insoluble (type S or slowly transportable in 

the lungs), but can be highly insoluble (type SS). Exceptions, such as plutonium metal associated 

with solvents, might exist. Plutonium in chemical processing operations can be either soluble (type M 

or moderately transportable in the lungs) or insoluble (type S). The solubility of plutonium should be 

selected based on what is most favorable to the claimant for the organ of interest [5].

The AMAD of airborne 239/240Pu and 241Am varies according to the source and therefore according to 

location on the Plant site. For routine releases from stacks and vents in which high-energy particulate 

air (HEPA) filters were operating as designed, the particle size of stack-effluent particles was reported 

to be on the order of 0.3 μm AMAD (Rood and Till 1999; Grogan et al. 2000). The AMADs of particles 

from the two larger fires (1957 and 1969) were not assessed, but there was evidence that the HEPA 

filtration systems did not remain intact throughout these events (Voillequé and Till 1999a, 1999b). A 

study of aerosols from another RFP fire involving plutonium and solvents indicated a mass median 

diameter on the order of 0.32 μm for this incident (Mann and Kirchner 1967), which corresponds to an 

AMAD of approximately 1-μm using the correlation from Hayden (1975) for RFP environmental 

plutonium and stack effluent air. However, the sitewide maximum intakes, based on the highest 

annual average concentration for any given sampler location, in Table 4-3 often reflect the air 

concentrations at the eastern edge of the site that resulted from suspension and resuspension of soil 

contaminated with 239/240Pu and 241Am from the 903 Area. The AMAD of airborne particles containing 

plutonium in this area of RFP has been characterized as ranging from 2 to 7 μm (Grogan et al. 2000). 

Although the physical diameters of plutonium particles in soil were found to be on the order of 0.3- to 

1-μm AMAD, it appears that the airborne plutonium particles in this area were attached to soil 
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particles, resulting in an aerosol most appropriately characterized by an AMAD of approximately 5 μm 

(Grogan et al. 2000).

Therefore, the AMAD is both time- and location-dependent for airborne radionuclides at RFP. 

Unfortunately, the relative contributions of the various sources of airborne plutonium at specific 

outdoor work locations are not known. Most of the work locations at RFP were upwind of the 903 

Area plutonium source because the predominant wind direction at RFP is from the northwest 

(Daugherty 1989). Measurements of soil concentrations of plutonium in 1988 around RFP, at 

distances of 1 and 2 mi from the center of the Plant, indicated dramatically larger concentrations east 

and southeast of the 903 Area than in other areas (Daugherty 1989). However, the degree to which 

the concentrations upwind of the 903 Area were influenced by resuspended plutonium is not known. 

Outdoor workers in the vicinity of the buildings from which routine releases occurred, and upwind of 

the 903 Area, could have been exposed to particulates with AMADs on the order of 0.3 μm, although 

resuspended particles would also be present at those locations. The following recommendations are 

made based on the information given above. For estimating intakes before 1965 (Table 4-2), an 

AMAD of 1.0 μm should be assumed for airborne ambient 239/240Pu and 241Am because worker intakes 

largely resulted from routine releases, the 1957 fire, and any resuspension of deposited 239/240Pu and 

241Am that occurred in the worker’s vicinity. An AMAD of 1.0 μm should also be assumed for intakes 

occurring during 1965, 1966, and 1970 to 1993 [6]. The disturbance of the 903 Area as part of an 

attempt to remove leaking barrels, along with subsequent high-wind events that served as the main 

dispersal mechanism for plutonium-contaminated soils in the 903 Area, occurred between 1967 and

1969. During 1967, 1968, and 1969, and after 1993, an AMAD of 5 μm should be assumed [7]. The 

sitewide maximum intakes, based on the highest annual average concentration for any given sampler 

location, from 1967 to 1969 (Table 4-3) are dominated by the suspended plutonium that originated 

from the 903 Area before placement of the asphalt pad. After 1993, when production had ceased, 

resuspension of plutonium is the mostly likely source of airborne plutonium. 

The recommendation to assume an AMAD of 1.0 μm from 1970 through 1993 is based on the fact 

that air concentrations downwind of the 903 Area, which are better characterized by an AMAD of 

5.0 μm, tended to be only slightly (less than an order of magnitude) higher than other onsite areas, but 

not always. In 1972, the onsite airborne concentrations downwind of the 903 Area were 2 to 3 times 

higher than in other areas of RFP (Dow 1972–1973). However, in 1990 to 1992, the air 

concentrations in the main production areas of RFP (northern section of the industrial zone) exceeded 

those downwind of the 903 Area.

These assumptions are favorable to the claimant in the following respects: (1) for most organs, 

assuming an AMAD of 1.0 μm increases the dose by about a factor of 1.5 to 1.9 over the dose 

calculated by assuming an AMAD of 5.0 μm; and (2) using the sitewide maximum intakes, based on 

the highest annual average concentration for any given sampler location, often implicitly assumes the 

worker was exposed to the air concentrations downwind of the 903 Area, which was not the location 

of most exposures. The extrathoracic airways dose factor is a factor of 1.5 to 1.9 times higher for the 

AMAD assumption of 5 μm (the particle size more appropriate for resuspended plutonium) versus 1.0 

μm (ICRP 2001). Therefore, for cases in which the extrathoracic airways [ET, ET1, ET2, LN(ET)] 

dose is of most interest, the AMAD of 5.0 μm should be assumed for all years.

4.3 EXTERNAL EXPOSURE TO ONSITE ATMOSPHERIC RADIONUCLIDE 

CONCENTRATIONS

4.3.1 Radionuclides of Concern

As described in Section 4.2.1, 3H, natural thorium, enriched and depleted uranium, 239/240Pu, 241Pu, 

and 241Am were identified as having been released to the air during the RFP operational period. 
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However, because none of the isotopes of concern is a strong gamma emitter, there is little external 

dose. 

4.3.2 Exposure Rates

Before 1975, external exposure of workers was determined by the use of film badges. Film badges 

are not well suited to environmental monitoring, and environmental measurements before 1975 are 

not readily available. Rope et al. (1999) pointed out that before the early 1970s, environmental data 

were fewer and of lower quality than later data. In his review of RFP (covering 1952 to 1982), Putzier 

(1982) spent little time discussing external occupational exposure measurements and none describing 

outdoor measurements. This is largely because the concern about environmental exposures to 

workers or the public was centered on plutonium. Rope et al. (1999) described external gamma 

exposures, but the information is limited to an analysis of aerial survey data that targeted plutonium by 

measuring 241Am. 

Data that can be used to estimate external environmental dose are available in the annual 

environmental reports for 1975 to 1994 (see the Environmental Reports section of the References). 

Gamma exposure rates were routinely measured at 12 to 15 locations on the site. Those data are 

plotted in Figure 4-2 for continuous exposures during a year (8,760 hr) and summarized in Table 4-4 

for 2,500 hr/yr exposures. The locations of the monitoring stations were not available, but a sitewide

maximum value was estimated by adding the recommended standard deviation (described below), 

reflecting both spatial and temporal variation, to the sitewide mean value [8].
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Figure 4-2. External dose (mrem/yr) as a function of year. 

 On-site Environmental Gamma Exposures at Rocky Flats Plant

0

50

100

150

200

250

1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

Year

mrem/yr

Annual Average Annual Maximum

For the 19-yr period from 1975 to 1993, the number of independent measurements ranged from 87 to 

176 per year. Table 4-4 lists the reported means and standard deviations (2σ) of the measured 

samples for these years with the exception of 1977. For 1977, only the mean was reported. There is 

no explanation available for the relatively large standard deviations in 1975, 1976, and 1978. Due to 

this large variation in reported standard deviations, a recommended standard deviation value (1σ) 

was developed based on the largest reported standard deviation. The recommended standard 

deviation in Table 4-4 is based on the 1975 value, which is calculated to be 18% of the mean. This 

recommendation is favorable to claimants because it results in higher calculated maximum dose 

rates [9]. 
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Table 4-4. External gamma radiation (mrem/yr).a

Year

Number of 

measurements

Reported mean

dose rate

Reported 

standard 

deviation (2σ)

Recommended 

standard 

deviation (σ)

Maximum dose 

rateb,c 

1953–1964 No data 39c No data 7 53

1965–1970 No data 56c,d No data 10 76

1971–1974 No data 39c No data 7 53

1975 87 32 11 6 44

1976 134 32 10 6 44

1977 98 37 9 7 51

1978 126 37 10 7 51

1979 133 42 3 8 58

1980 131 45 2 8 61

1981 125 38 2 7 52

1982 120 35 1 6 47

1983 135 40 1 7 54

1984 142 42 2 8 58

1985 93 43 2 8 59

1986 147 39 1 7 53

1987 100 44 1 8 60

1988 109 44 2 8 60

1989 132 48 1 9 66

1990 143 44 1 8 60

1991 108 35 1 6 47

1992 176 35 1 6 47

1993 176 39 1 7 53

After 1993 No data 39c No data 7 53

Mean 1975–1993 Not applicable 39c Not applicable 7 Not applicable

a. Dose rate corresponding to an exposure time of 2,500 hr/yr.

b. Calculated by adding the recommended 2 x standard deviation to the mean dose rate, which is 18% of the mean.

c. Average of means reported for 1975 through 1993.

d. The calculated contribution from americium in barrel storage area before placement of asphalt pad was determined to 

be 17 mrem/yr. 

There is no significant trend to the means and maximums plotted in Figure 4-2. As mentioned above, 

effluents from RFP were largely alpha-emitting radionuclides with no substantial gamma component 

with the exception of 241Am. Releases attributable to incidents that might have vented outside 

buildings, or due to suspension or resuspension of contaminated soil, would not tend to increase the 

gamma exposure rate appreciably due to the relatively large contribution of naturally occurring 

radioactivity to measured exposure rates. Workers subject to environmental doses from such 

incidents would be affected to a far greater extent by internally deposited radionuclides. 

Therefore, it is reasonable to assign the average value of 39 ± 7 mrem/yr (2,500 hr) to years not listed 

in this table. This value represents the average of means corresponding to the 19 yr for which 

measurements were reported. The assumed standard deviation associated with this average value is 

based on the assumed 18% standard deviation. This dose rate represents the total dose, including 

background, so use of these values in estimating individual worker doses is favorable to the claimant.

The listed mean dose rate, in Table 4-4, should be assigned as a normal distribution with the error as 

twice the recommended standard deviation as a best estimate for a 2,500-hour work year exposure. 

Dose rates should be scaled to account for occupancy times other than 2,500 hr of exposure.

Ambient onsite gamma is significantly larger (p <0.05) than ambient gamma measured at “perimeter” 

stations, but only by an average of 9% for years for which data were reported (see the Environmental 

Reports section of the References). This would seem to indicate that about 3 mrem/yr (for a 
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2,500-hr/yr exposure) could be contributed by contamination inside the exclusion zone boundary for 

these years. Therefore, increases in airborne contamination do not necessarily indicate significant 

increases in total external dose. However, between 1965 and 1970, the large increase in inhalation 

intake of plutonium is due to soil contamination of the 903 Area before paving of that area. It is likely 

that the external dose rate at that location might have been elevated in comparison with other 

locations at the site due to the 241Am present. Unfortunately, soil concentrations in the barrel storage 

location are not available and few soil concentration data are available for the site before 1969 (Rood, 

Grogan, and Till 1999). In an attempt to estimate external dose to an onsite worker from 

contaminated soils in the vicinity of the 903 storage area, a plutonium soil contamination value of 

26 μCi/m2 (9.6 × 105 Bq/m2

) was assumed based on the 1973 site environmental report, which was 

the maximum observed value in 1970 just downwind of the 903 Pad. Using Federal Guidance Report 

(FGR) No. 12 (Eckerman and Ryman 1993) dose conversion factors for surface-contaminated soils, 

assuming that the maximum observed concentration was constant over the entire site, and using the 

mean isotopic ratio reported by Krey et al. (1976) for 241Am/239Pu in RFP soil of 0.13, doses can be 

calculated at 1 m above ground surface of approximately 3 mrem/yr (for 2,500-hr/yr exposure). 

Another approach taken to estimate the soil concentration in the barrel storage area before paving 

was based on estimates of the total 239Pu released. According to Weber et al. (1999), the highest 

release estimate for 239Pu in the 903 storage area was on the order of 1,000 g, which corresponds to 

62 Ci. If one assumes that this is spread over the 550- by 475-ft contamination zone of the 903 Area 

originally described (Weber et al. 1999), a maximum estimate of external dose of 17 mrem/yr for 

241Am was obtained [assuming the Krey et al. (1976) mean isotopic ratio of 13% for 241Am:239Pu, the 

appropriate FGR 12 dose conversion factor, a depth of contamination of 15 cm, and 2,500-hr/yr 

exposure]. 

Finally, this TBD analysis attempted to ascertain what other sources of external exposure might have 

been present. Using dose factors in FGR No. 12 (Eckerman and Ryman 1993), the analysis 

calculated external dose from submersion in air containing 241Am. The 241Am levels were calculated 

using isotopic ratios published by Krey et al. (1976) and modified by Radiological Assessments 

Corporation when developing soil action levels for RFETS. Doses from 241Am in that scenario were 

negligible, less than 1 μrem/yr. 

The results of these considerations suggest that use of the ambient gamma values for external 

environmental dose is reasonable for unmonitored workers throughout the lifetime of the site, with the 

possible exception of the period after plutonium began leaking from the barrel storage area and 

before placement of the asphalt pad in that area. The maximum estimated increment to the 

measured ambient gamma levels was calculated to be 17 mrem/yr for a 2,500-hr/yr exposure. 

Therefore, this quantity should be added to the measured mean gamma level (39 mrem/yr) applied for 

1965 to 1970. 

4.4 UNCERTAINTY

Uncertainties in estimates of plutonium intake and external dose to a workers at RFP are associated 

with natural variations in environmental concentrations, lack of precise information about locations 

and durations of exposures, and limitations of monitoring data. Not all of these uncertainties can be 

quantified.

4.4.1 Uncertainty in Internal Exposure Estimates

4.4.1.1 Estimated Intakes, 1953 to 1964

The following discussion on uncertainties in the atmospheric dispersion model predictions used to 

estimate intakes for the period from 1953 to 1964 interprets the pertinent text from a Phase II 
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document by Rood, Grogan, and Till (1999). Uncertainties in model calculations of integrated air 

concentration and intake (Section 4.2.3) arise from model and parameter uncertainty. Model 

uncertainty arises from the inability of the computational algorithms to describe rigorously and 

precisely the physical processes that govern the behavior of the system, due either to insufficient 

knowledge of the processes or inability to measure isolated mechanisms that drive the processes. 

Model uncertainty is often evaluated in a process called “model validation,” which compares model 

predictions to measured parameters that have not been used to calibrate the model.

Parameter uncertainty arises because of lack of knowledge about, or inability to measure accurately, 

a parameter’s true value. A parameter uncertainty analysis requires the specification of probability 

distributions describing the value of a parameter considered to be uncertain. The assigned 

distribution of a parameter characterizes the degree of belief that the true but unknown value lies 

within a specified range of values. 

The Phase II modeling effort performed parameter uncertainty analysis and model validation. Input 

distributions characterizing the source term, fate and transport calculations, and risk coefficients were 

developed for the model.

The Phase II dispersion modeling for the identified continuous and discrete sources of plutonium to 

the air at RFP used Monte Carlo simulations combined with simple random sampling to propagate 

uncertainty through the model. In simple random sampling, a random value is taken from the 

distribution specified for each uncertain model parameter and a single estimate of the desired 

endpoint is calculated. This process is repeated for a specific number of model realizations. The 

result is an empirical approximation of the probability distribution of the model output.

In the application of the Phase II dispersion model, model output (in curies per year of annual intake 

and converted to becquerels per year of intake for Table 4-2) was developed from 500 model 

realizations each year and categorized into a percentile ranking. The ordered statistics for the 5th and 

95th percentiles for 500 model realizations are 25 and 475, respectively. That is, if the output values 

for 500 realizations are sorted in ascending order, the 5th percentile represents the 25th highest value 

and the 95th percentile represents the 475th highest value. The distribution associated with the 

percentiles is not readily described as either normal or lognormal.

The components of uncertainty reflected in the annual intake estimates reflect uncertainty only in the 

source terms and environmental transport. Such components of uncertainty are real in the sense that 

they can be derived from measured quantities or inferred from historical records. Uncertainty related 

to exposure scenarios (i.e., location and duration of exposure) were not included in the calculated 

statistics. 

4.4.1.2 Estimated Intakes, After 1964 

Uncertainties associated with the reported average annual 239/240Pu air concentrations for the site are 

provided for 1972 to 1976 and 1989 to 1994 in the annual environmental reports (see the 

Environmental Reports section of the References). For these years, error terms representing two 

standard deviations about the mean (at the 95% confidence level) were calculated assuming the 

measurements were normally distributed. In 1977 and 1978, no error terms were reported because 

“they can be misleading and (their use) is considered inappropriate for the data in this report” (Barker

et al. 1978; Bokowski et al. 1979). These two reports state that the sampling methods would result in

“nonrandom variations in the measured concentrations,” and the “distribution ... would not be normal.” 

From 1979 to 1988, error terms were reported, but only by sampler location and not normalized to the 

site average. The error terms, when reported, were based on counting error alone and therefore 

represent the minimum error that can be associated with the measurements. Although counting error 

does contribute to data uncertainty, the uncertainty associated with a given average value for the site 
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is also be a function of variability in environmental conditions as well as a function of both time and 

location. Therefore, the reported confidence limits (CLs) are not useful in estimating uncertainty 

associated with a site average because they would undoubtedly underestimate that uncertainty.

4.4.2 Uncertainties in External Dose Estimate

Unquantifiable uncertainty in external exposures results from the lack of readily available data before 

1975 or after 1993. However, onsite measurements made during that 19-yr period indicate no 

significant upward trend to indicate that Plant operations were increasing onsite exposures. 

Published data for environmental external measurements have normal statistics associated with them. 

The data in Table 4-4 vary considerably in the expression of uncertainty from the annual 

environmental reports. For years before 1977, no uncertainty data are available. For other years, the 

uncertainties vary from as much as 18% (1σ) for 1975 to less than 2% for 1983. This TBD 

recommends using the maximum uncertainty available in the records, 18%, which is represented by 

1981 data. The annual recommended values of uncertainty, expressed in terms of 1σ, are listed in 

Table 4-4. 

4.5 ATTRIBUTIONS AND ANNOTATIONS

Where appropriate in this document, bracketed callouts have been inserted to indicate information, 

conclusions, and recommendations provided to assist in the process of worker dose reconstruction. 

These callouts are listed here in the Attributions and Annotations section, with information to identify 

the source and justification for each associated item. Conventional References, which are provided in 

the next section of this document, link data, quotations, and other information to documents available 

for review on the Project’s Site Research Database (SRDB).

[1] McDowell-Boyer, Laura M. Oak Ridge Associated Universities (ORAU) Team. Environmental 

Engineer. July 2006.

The recommendation to ignore contributions of 238Pu and 241Pu is based on the facts that 

(1) their total alpha activity contributions are less than 5% of those of 239Pu and 240Pu based on 

the reported isotopic composition of plutonium at RFP, and (2) the maximum inhalation organ 

dose factors for 238Pu and 241Pu are equal to or less than those for 239Pu and 240Pu. Therefore, 238Pu and 241Pu do not contribute more than a few percent of the dose from plutonium.

[2] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

ORAUT-PROC-0031, Site Profile and Technical Basis Document Development (ORAUT 

2012), provides guidance in TBD preparation, and specifies that maximum sitewide annual 

median intakes via inhalation will be provided.

[3] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

The measurements by Poet and Martell (1972) indicated that the mean activity ratio in soil 

ranged from 0.03 to 0.17, but the authors acknowledged that low recovery yields associated 

with their laboratory procedures resulted in large errors for their 241Am results. Krey et al. 

(1976) measured the 241Am/239Pu ratios in soil, and found a range from 0.10 to 0.20 with a 

mean of 0.13 and standard deviation of 0.03. Both authors acknowledged that the ratio would 

increase over time and peak 70 to 80 yr after plutonium purification (around 2030). Assuming 

the initial isotopic composition of plutonium from Section 4.2.1, with 241Pu at 0.36%, the 

resulting peak ratio would be about 0.18 (Poet and Martell claimed this peak was 0.54, but had 

assumed an isotopic ratio of 1% for 241Pu, which is almost 3 times too high). In 1996, Litaor 

and Allen (1996) found an average onsite ratio of 0.19, but they indicated difficulties related to 

high analytical errors with 241Am. Therefore, due to uncertainty in the relative movement of the 

two isotopes in soil, a higher value of 0.30 is recommended.
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[4] Rood, Arthur S. K-Spar Inc. President. July 2006.

The puff trajectory model, Regional Atmospheric Transport Code for Hanford Environmental 

Tracking (RATCHET), was adapted by Arthur S. Rood from its use for the Phase II Historical 

Public Exposures Studies for RFP for use in estimating onsite inhalation intakes from 1953 to 

1964. The model and adaptations are described in Attachment A, Section A.2. 

[5] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Due to variations in the original source of particles (fires, cutting oil, etc.) and environmental 

factors, it is recommended that the dose reconstructor always make a selection of dose factor 

that is favorable to claimants in relation to plutonium solubility.

[6] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. January 2007.

The recommendation to assume the default ICRP Publication 66 AMAD of 1.0 μm 

(“recommended for exposure in the general environment”; ICRP 1994) during certain periods 

results in using inhalation organ dose factors that are higher than those for larger respirable 

particles (those on the order of 5 μm). The cited literature indicates that intakes from 

plutonium released routinely or from fires during the 1953-to-1966 and 1970-to-1993 periods 

are possibly smaller than the 5-μm ICRP Publication 66 default recommended for 

“occupational exposure settings” due in part to the presence of HEPA filter banks at the 

emission points.

[7] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Plutonium-contaminated particles suspended or resuspended from soil and other surfaces are 

known to contribute a significant portion of the airborne activity of plutonium in certain areas of 

the RFP site, and many of these particles are better characterized by an AMAD of 5 μm. From 

1967 to 1969, a number of high-wind events occurred during and after removal of leaking 

barrels containing plutonium-contaminated cutting oil in the 903 Area, which resulted in 

dispersal of significant quantities of contaminated soil particulates, mainly in the easterly to 

southeasterly direction from the 903 Area. The sitewide maximum air concentrations, and

resulting estimated intakes, are associated with this region of RFP. The airborne plutonium in 

this region is best characterized by an AMAD of 5 μm. After 1993, production had ceased, 

and it is therefore reasonable to expect that the main source of airborne plutonium was

resuspension from soil or surfaces and that HEPA-mediated emissions would no longer have 

occurred.

[8] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

ORAUT-PROC-0031, Site Profile and Technical Basis Document Development (ORAUT 

2012), provides guidance in TBD preparation and specifies that a site average value be 

provided along with the standard deviation and a maximum onsite dose rate (derived by 

adding the standard deviation to the average).

[9] Little, Craig A. ORAU Team. Radioecologist/Health Physicist. 2006

The average of the reported standard deviations (2σ) without the 1975-to-1978 values is 

approximately 5. The recommended value of 1σ is approximately 10 times higher than most 

reported values due to the uncertainty posed by the unexplained larger variabilities in 1975, 

1976, and 1978. This is an upper bound on the uncertainty, and the resulting estimates of the 

maximum dose rate are therefore favorable to claimants.

[10] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Rope et al. (1999, pp. 108–109) did an extensive review of environmental data available for 

the RFP site and based this least-squares, best-fit estimate of the plutonium contribution to 

TLLα on data from the Health and Safety Laboratory and Dow, making standard temperature 

and pressure corrections as necessary. The results were very close to an estimate made by 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 24 of 57

 

another researcher who, rather than using a best-fit analysis, assumed a value between 33% 

and 50% based on a log-log plot of data from CDPHE. The Rope et al. value appears to carry 

more scientific weight, but it is not in conflict with the other results. Therefore, the value of 

0.36 is considered the best estimate available for the period of interest.

[11] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

An electronic presentation addressing special monitoring during decommissioning and 

demolition projects at RFETS indicates that impacts from various demolition projects 

undertaken in 1999 (Building 779 glovebox strip-out, Building 729 stack removal, Building 788 

demolition, Building 729 demolition, Building 729 clarifier tank removal) were not significant in 

terms of measured isotopic air concentrations.

[12] Rood, Arthur S. K-Spar Inc. President. July 2006.

Mr. Rood developed the RATCHET application for the Phase II Historical Public Exposure 

Studies project. He made modifications to the model for this study using the same source 

terms identified in the earlier work.

[13] Rood, Arthur S. K-Spar Inc. President. July 2006.

The Building 776 stack conforms to the U. S. Environmental Protection Agency (EPA) 

definition of good engineering practice design. According to the EPA 1995 Building Profile 

Input Program, building wake effects extend out to 5 times the lesser of the building height or 

the building perimeter width, such that Building 771 is the only building within the sphere of 

influence of the 776 stack. The 776 stack must be at least 29 m high (since the Building 771 

height is 11.6 m) to conform to good engineering practice and therefore be free of the effects 

of building wakes. Because the 776 stack is 44 m high, building wake effects are not a 

concern.

[14] Rood, Arthur S. K-Spar Inc. President. July 2006.

The other modeled elevated sources were the Building 776 roof vents. Because some of the 

roof vents were an inverted “J” type, effluent was directed down toward the roof, thereby 

distributing the source across the roof surface. To account for this, Building 776 was modeled 

not as a point source but as an elevated area source and initial dispersion coefficients were 

assigned. The coefficients implicitly account for the effects of building wakes by driving the 

plume initially down to the ground surface.

[15] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Rope et al. (1999, pp. 108–109) did an extensive review of environmental data available for 

the RFP site and based this least-squares, best-fit estimate of the plutonium contribution to 

TLLα on data from the Health and Safety Laboratory and Dow, making standard temperature 

and pressure corrections as necessary. The results were very close to an estimate made by 

another researcher who, rather than using a best-fit analysis, assumed a value between 33% 

and 50% based on a log-log plot of data from CDPHE. The Rope et al. value appears to carry 

more scientific weight, but it is not in conflict with the other results. Therefore, the value of 

0.36 is considered the best estimate available for the period of interest.

[16] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

There is no evidence that background radioactivity in the Denver area would be significantly 

different from that in the RFP area; therefore, this assumption is reasonable.

[17] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Radionuclides other than 239/241Pu and 241Am that have been released from RFP and contribute 

less than 1-mrem/yr dose to any organ in the year of maximum release are not expected to 

contribute more than 5% of the total environmental dose in comparison with the maximum 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 25 of 57

 

dose contributions of 239/240Pu and 241Am in the same year. This was verified by comparing the 

maximum estimated doses for these other radionuclides (Attachment B, Tables B-1 to B-3) 

and the sitewide maximum doses associated with the 239/240Pu and 241Am inhalation intake 

values in Tables 4-2 and 4-3.

[18] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

This statement is supported by the text following it, which demonstrates considerable effort by 

ChemRisk to review effluent monitoring data, including raw data when necessary. It is 

important to recognize that ChemRisk reevaluated the uncertainty associated with the

reviewed data and proposed larger uncertainties due to possible measurement and recording 

errors.
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 26 of 57

 

REFERENCES

ChemRisk, 1992, Project Tasks 3&4, Final Draft Report, Reconstruction of Historical Rocky Flats 

Operations & Identification of Release Points, Alameda, California, August. [SRDB Ref ID: 

8016]

ChemRisk, 1994a, Project Task 5 Report, Estimating Historical Emissions from Rocky Flats 1952–

1989, Alameda, California, March. [SRDB Ref ID: 8017]

ChemRisk, 1994b, Project Task 8 Report, Dose Assessment for Historical Contaminant Releases 

from Rocky Flats, Alameda, California, September. [SRDB Ref ID: 8018]

DOE (U.S. Department of Energy), 1980, Final Environmental Impact Statement, Rocky Flats Plant 

Site, Golden, Jefferson County, Colorado, DOE/EIS-0064, Washington, D.C., April. [SRDB 

Ref IDs: 11505, 11507, 11508] 

Dow Chemical U.S.A., 1972–1973, collection of environmental sampling results, January to 

December 1972, Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 1081]

Eckerman, K. F., and J. C. Ryman, 1993, External Exposure to Radionuclides in Air, Water, and Soil,

Federal Guidance Report No. 12, EPA-402-R-93-081, U.S. Environmental Protection Agency, 

Office of Radiation and Indoor Air, Washington, D.C., September. [SRDB Ref ID: 11997]

Grogan, H. A., W. K. Sinclair, P. G. Voillequé, and J. E. Till, 2000, Final Report, Assessing Risks of 

Exposure to Plutonium, RAC Report No. 5-CDPHE-RFP-1998-FINAL(Rev.2), Radiological 

Assessments Corporation, Neeses, South Carolina, February. [SRDB Ref ID: 26106]

Hayden, J. A., 1975, “Characterization of Environmental Plutonium by Nuclear Track Techniques,” 

Atmosphere-Surface Exchange of Particulate and Gaseous Pollutants (1974), Proceedings of 

a Symposium Held at Richland, Washington, September 4-5, 1974, ERDA Symposium Series 

38, CONF-740921, U.S. Energy Research and Development Administration, Washington, 

D.C., pp. 648–660. [SRDB Ref ID: 29197]

ICRP (International Commission on Radiological Protection), 1975, Report of the Task Group on 

Reference Man, Publication 23, Pergamon Press, Oxford, England. [SRDB Ref ID: 22735]

ICRP (International Commission on Radiation Protection), 1994, Human Respiratory Tract Model for 

Radiological Protection, Publication 66, Pergamon Press, Oxford, England. [SRDB Ref ID: 

22732]

ICRP (International Commission on Radiological Protection), 2001, ICRP CD1: Database of Dose 

Coefficients: Workers and Members of the Public, Pergamon Press, Oxford, England. [SRDB 

Ref ID: 175790] 

Krey, P., E. Hardy, H. Volchok, L. Toonkel, R. Knuth, M. Coppes, and T. Tamura, 1976, Plutonium 

and Americium Contamination in Rocky Flats Soil - 1973, HASL-304, U.S. Energy Research 

and Development Administration, Health and Safety Laboratory, New York, New York, March. 

[SRDB Ref ID: 10153]

Litaor, M. I., and L. Allen, 1996, “A Comprehensive Appraisal of 241Am In Soils Around Rocky Flats, 

Colorado,” Health Physics, volume 71, number 3, pp. 347–357. [SRDB Ref ID: 24797]
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 27 of 57

Mann, J. R., and R. A. Kirchner, 1967, “Evaluation of Lung Burden Following Acute Inhalation 

Exposure to Highly Insoluble PuO2,” Health Physics, volume 13, pp. 877–882. [SRDB Ref ID: 

7974]

NIOSH (National Institute for Occupational Safety and Health), 2010, Radiation Exposures Covered 

for Dose Reconstructions Under Part B of the Energy Employees Occupational Illness 

Compensation Program Act, DCAS-IG-003, Rev. 1, Division of Compensation Analysis and 

Support, Cincinnati, Ohio, October 5. [SRDB Ref ID: 88929]

NIOSH (National Institute for Occupational Safety and Health), 2013, SEC Petition Evaluation Report, 

Petition SEC-00192, Rev. 1, Division of Compensation Analysis and Support, Cincinnati, Ohio, 

September 30. [SRDB Ref ID: 132777]

O’Kula, K. R., and C. E. Murphy, Jr., 2001, Crediting Tritium Deposition in Accident Analysis, WSRCMS-2001-00112, Westinghouse Savannah River Company, Aiken, South Carolina. [SRDB 

Ref ID: 24845]

ORAUT (Oak Ridge Associated Universities Team), 2012, Site Profile and Technical Basis Document 

Development, ORAUT-PROC-0031, Rev. 04, Oak Ridge, Tennessee, November 5. [SRDB 

Ref ID: 166849]

ORAUT (Oak Ridge Associated Universities Team), 2020, Rocky Flats Plant – Occupational Internal 

Dose, ORAUT-TKBS-0011-5, Rev. 04, Oak Ridge, Tennessee, September 1. [SRDB Ref ID: 

178626]

Poet, S. E., and E. A. Martell, 1972, “Plutonium-239 and Americium-241 Contamination in the Denver 

Area,” Health Physics, volume 23, pp. 537–546. [SRDB Ref ID: 166850] 

Putzier, E. A., 1982, The Past 30 Years at Rocky Flats Plant, Rockwell International, Rocky Flats 

Plant, Golden, Colorado, November. [SRDB Ref ID: 4632] 

Rood, A. S., and J. E. Till, 1999, Final Report, Estimated Exposure and Lifetime Cancer Incidence 

Risk from Routine Plutonium Releases at the Rocky Flats Plant, RAC Report No. 8 CDPHERFP-1997-FINAL(Rev.1), Radiological Assessments Corporation, Neeses, South Carolina, 

August. [SRDB Ref ID: 26107] 

Rood, A. S., H. A. Grogan, and J. E. Till, 1999, Final Report, Comprehensive Assessment of 

Exposure and Lifetime Cancer Incidence Risk from Plutonium Released from the Rocky Flats 

Plant, 1953–1989, RAC Report 13-CDPHE-RFP-1999-FINAL, Radiological Assessments 

Corporation, Neeses, South Carolina, September. [SRDB Ref ID: 7999]

Rope, S. K, K. R. Meyer, M. J. Case, H. A. Grogan, D. W. Schmidt, M. Dreicer, T. F. Winsor, and 

J. E. Till, 1999, Final Report, Evaluation of Environmental Data for Historical Public Exposures 

Studies on Rocky Flats, RAC Report 1-CDPHE-RFP-1997-FINAL(Rev. 1), Radiological 

Assessments Corporation, Neeses, South Carolina, August. [SRDB Ref ID: 8008]

Sebelius, K., 2013, HHS Designation of Additional Members of the Special Exposure Cohort Under 

the Energy Employees Occupational Illness Compensation Program Act of 2000 Designating a 

Class of Employees from Rocky Flats Plant Golden, Colorado, U.S. Department of Health and 

Human Services, Office of the Secretary, Washington, D.C., December 12. [SRDB Ref ID: 

166855] 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 28 of 57

 

Unknown, 1992, Colorado Federal District Court Report of the Federal District Special Grand Jury 89-

2 January 24, 1992, January 24. [SRDB Ref ID: 126910] 

Voillequé, P. G., and J. E. Till, 1999a, Final Report, 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. [SRDB Ref ID: 8006]

Voillequé, P. G., and J. E. Till, 1999b, Final Report, 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. [SRDB Ref ID: 8779]

Voillequé, P. G., and J. E. Till, 1999c, Final Report, 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. [SRDB Ref ID: 8007]

Voillequé, P. G., and J. E. Till, 1999d, Final Report, Results of Screening Calculations to Assess the 

Relative Importance of Rocky Flats Uranium Releases, RAC Report No. 11-CDPHE-RFP1999-FINAL, Radiological Assessments Corporation, Neeses, South Carolina. August. [SRDB 

Ref ID: 32101]

Weber, J. M., A. S. Rood, H. R. Meyer, and J. E. Till, 1999, Final Report, 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. [SRDB Ref ID: 

8012]

Environmental Reports by Year

1971

Steward, L. M., and M. R. Boss, 1972, Annual Report: Environmental Safeguard ’71, Radioactive 

Monitoring and Environmental Surveillance, January Through December 1971, RFP-ENV-718, 

Dow Chemical U.S.A., Rocky Flats Plant, Golden, Colorado, March 10. [SRDB Ref ID: 962]

1972

Boss, M. R., F. D. Hobbs, R. W. Loser, and D. E. Michels, 1973, Annual Environmental Monitoring 

Report, Rocky Flats Plant, January Through December 1972, RFP-ENV-72, Dow Chemical 

U.S.A., Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 963]

1973

Allen, I. B., D. C. Coonfield, R. R. Gunning, F. D. Hobbs, C. T. Illsley, and J. M. West, 1974, Annual 

Environmental Monitoring Report, Rocky Flats Plant, A USAEC-Owned Facility, January 

through December 1973, RFP-ENV-73, Dow Chemical U.S.A., Rocky Flats Plant, Golden, 

Colorado, April 26. [SRDB Ref ID: 966]

1974

Allen, I. B., C. J. Barker, M. R. Boss, D. C. Coonfield, R. R. Gunning, F. D. Hobbs, J. F. Palmer, L. J. 

Walker, G. J. Werkema, and J. M. West, 1975, Annual Environmental Monitoring Report, U.S. 

Energy Research and Development Administration, Rocky Flats Plant, January through 

December 1974, RFP-ENV-74, Rocky Flats Plant, Dow Chemical U.S.A., Golden, Colorado, 

April 30. [SRDB Ref ID: 973]
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1975

Allen, I. B., C. J. Barker, D. L. Bokowski, M. R. Boss, D. C. Coonfield, R. W. Hawes, J. F. Palmer, L. J. 

Walker, J. M. West, and W. F. Williams, 1976, Annual Environmental Monitoring Report, 

Rocky Flats Plant, January through December 1975, RFP-ENV-75, Rockwell International, 

Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 975]

1976

Barker, C. J., D. L. Bokowski, M. R. Boss, D. C. Coonfield, R. W. Hawes, R. L. Henry, C. T. Illsley, L. 

J. Walker, J. M. West, and W. F. Williams, 1977, Annual Environmental Monitoring Report,

U.S. Energy Research and Development Administration Rocky Flats Plant, January through 

December 1976, RFP-ENV-76, Rockwell International, Rocky Flats Plant, Golden, Colorado, 

May 6. [SRDB Ref ID: 977]

1977

Barker, C. J., D. L. Bokowski, M. R. Boss, D. C. Coonfield, A. D. Daniels, R. W. Hawes, R. L. Henry, 

C. T. Illsley, J. M. West, and W. F. Williams, 1978, Annual Environmental Monitoring Report,

U.S. Department of Energy Rocky Flats Plant, January through December 1977, RFP-ENV77, Rockwell International, Rocky Flats Plant, Golden, Colorado, April 25. [SRDB Ref ID: 

979]

1978

Bokowski, D. L., M. R. Boss, R. W. Hawes, R. L. Henry, C. T. Illsley, C. A. Kellner, R. D. Sherrill, L. F. 

Smith, and W. F. Williams, 1979, Annual Environmental Monitoring Report, U.S. Department 

of Energy, Rocky Flats Plant, January through December 1978, RFP-ENV-78, Rockwell 

International, Rocky Flats Plant, Golden, Colorado, May 15. [SRDB Ref ID: 983]

1979

Bokowski, D. L., R. B. Falk, R. L. Henry, C. T. Illsley, R. M. Neal, R. D. Sherrill, L. F. Smith, J. M. 

West, W. F. Williams, and J. L. Zoellner, 1980, Annual Environmental Monitoring Report, U.S. 

Department of Energy, Rocky Flats Plant, January through December 1979, RFP-ENV-79, R. 

D. Howerton, editor, Rockwell International, Rocky Flats Plant, Golden, Colorado, April 10. 

[SRDB Ref ID: 7913]

1980

Barker, C. J. , R. B. Falk, R. L. Henry, C. T. Illsley, N. D. Kirk, I. M. Meisel, R. V. Reischick, L. F. 

Smith, J. M. West, T. F. Winsor, and J. L. Zoellner, 1981, Annual Environmental Monitoring 

Report, U.S. Department of Energy, Rocky Flats Plant, January Through December 1980, 

RFP-ENV-80, R. D. Howerton, editor, Rockwell International, Rocky Flats Plant, Golden, 

Colorado, April 20. [SRDB Ref ID: 985]

1981

Rockwell International, 1982, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1981, RFP-ENV-81, Rockwell International, 

Rocky Flats Plant, Golden, Colorado, April 15. [SRDB Ref ID: 986]

1982

Rockwell International, 1983, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1982, RFP-ENV-82, Rockwell International, 

Rocky Flats Plant, Golden, Colorado, April 15. [SRDB Ref ID: 987]
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1983

Rockwell International, 1984, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1983, RFP-ENV-83, Rockwell International, 

Rocky Flats Plant, Golden, Colorado, April 15. [SRDB Ref ID: 3747]

1984

Rockwell International, 1985, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1984, RFP-ENV-84, Rocky Flats Plant, 

Golden, Colorado, March 25. [SRDB Ref ID: 988]

1985

Rockwell International, 1986, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1985, RFP-ENV-85, Rocky Flats Plant, 

Golden, Colorado, April 25. [SRDB Ref ID: 997]

1986

Rockwell International, 1987, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1986, RFP-ENV-86, Rocky Flats Plant, 

Golden, Colorado, April 27. [SRDB Ref ID: 998]

1987

Daugherty, N. M., editor, 1988, Annual Environmental Monitoring Report, U.S. Department of Energy, 

Rocky Flats Plant, January Through December 1987, RFP-ENV-87, Rockwell International, 

Rocky Flats Plant, Golden, Colorado, April 27. [SRDB Ref ID: 1000]

1988

Daugherty, N. M., editor, 1989, Rocky Flats Plant Site Environmental Report for 1988, January 

through December 1988, RFP-ENV-88, Rockwell International, Rocky Flats Plant, Golden, 

Colorado, May. [SRDB Ref ID: 1001]

1989

Boss, M. R., W. A. Busby, R. J. Crocker, N. M. Daugherty, L. A. Dunstan, P. F. Folger, B. R. Lewis, G. 

V. Porter, and R. H. Zuck, 1990, Rocky Flats Plant Site Environmental Report for 1989,

January through December 1989, RFP-ENV-89, D. B. Costain, editor, EG&G Rocky Flats, 

Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 1002]

1990

Costain, D. B., editor, 1991, Rocky Flats Plant Site Environmental Report for 1990, RFP-ENV-90, 

EG&G Rocky Flats, Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 1003]

1991

Cirrincione, D. A, editor, 1992, Rocky Flats Plant Site Environmental Report for 1991, RFP-ENV-91, 

EG&G Rocky Flats, Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 7916]

1992

Cirrincione, D. A, editor, 1993, Rocky Flats Plant Site Environmental Report for 1992, RFP-ENV-92, 

EG&G Rocky Flats, Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 1004]

1993

EG&G (EG&G Rocky Flats), 1994, Rocky Flats Environmental Technology Site, Site Environmental 

Report for 1993, RFP-ENV-93, Rocky Flats Environmental Technology Site, Golden, 

Colorado. [SRDB Ref ID: 1005]
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1994

KHC (Kaiser-Hill Company), 1995, Rocky Flats Environmental Technology Site, Site Environmental 

Report for 1994, RFP-ENV-94, Rocky Flats Environmental Technology Site, Golden, 

Colorado. [SRDB Ref ID: 1007]

1995

EG&G (EG&G Rocky Flats), 1995, Rocky Flats Environmental Technology Site Monthly 

Environmental Monitoring Report, April 1995, ER-4180110-222, Rocky Flats Environmental 

Technology Site, Golden, Colorado. [SRDB Ref ID: 4682]

RMRS (Rocky Mountain Remediation Services), 1995a, Monthly Environmental Monitoring Report, 

August 1995, RF/ER-95-0106-UN, Rocky Flats Environmental Technology Site, Golden, 

Colorado. [SRDB Ref ID: 4681]

RMRS (Rocky Mountain Remediation Services), 1995b, Monthly Environmental Monitoring Report, 

October 1995, RF/ER-95-0107-UN, Rocky Flats Environmental Technology Site, Golden, 

Colorado. [SRDB Ref ID: 4683]

1996 

RMRS (Rocky Mountain Remediation Services), 1996a, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, January - March 1996, RF/ER-96-0023.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4680]

RMRS (Rocky Mountain Remediation Services), 1996b, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, April - June 1996, RF/ER-96-0045.UN, Rocky 

Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4679]

RMRS (Rocky Mountain Remediation Services), 1996c, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, July - September 1996, RF/RMRS-96-0063, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4678]

RMRS (Rocky Mountain Remediation Services), 1997a, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, October - December 1996, RF/RMRS-97-005, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4677]

1997

RMRS (Rocky Mountain Remediation Services), 1997b, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, January - March 1997, RF/RMRS-97-027, Rocky 

Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4672]

RMRS (Rocky Mountain Remediation Services), 1997c, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, April - June 1997, RF/RMRS-97-050, Rocky Flats 

Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4670]

RMRS (Rocky Mountain Remediation Services), 1997d, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, July - September 1997, RF/RMRS-97-114.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4669]

RMRS (Rocky Mountain Remediation Services), 1998a, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, October - December 1997, RF/RMRS-98-216.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4668]
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1998

RMRS (Rocky Mountain Remediation Services), 1998b, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, January - March 1998, RF/RMRS-98243.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4665]

RMRS (Rocky Mountain Remediation Services), 1998c, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, April - June 1998, RF/RMRS-98243.UN, Rocky 

Flats Environmental Technology Site, Golden, Colorado. [SRDB Ref ID: 4660]

RMRS (Rocky Mountain Remediation Services), 1998d, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, July – September 1998, RF/RMRS-98287.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado, November. [SRDB Ref ID: 

4659]

RMRS (Rocky Mountain Remediation Services), 1999a, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, October - December 1998, RF/RMRS-99-329.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado, February. [SRDB Ref ID: 

4656]

1999

RMRS (Rocky Mountain Remediation Services), 1999b, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, January - March 1999, RF/RMRS-99-375.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado, May. [SRDB Ref ID: 4653]

RMRS (Rocky Mountain Remediation Services), 1999c, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, April - June 1999, RF/RMRS-99-421.UN, Rocky 

Flats Environmental Technology Site, Golden, Colorado, August. [SRDB Ref ID: 4652]

RMRS (Rocky Mountain Remediation Services), 1999d, Rocky Flats Environmental Technology Site

Quarterly Environmental Monitoring Report, July - September 1999, RF/RMRS-99-465.UN, 

Rocky Flats Environmental Technology Site, Golden, Colorado, November. [SRDB Ref ID: 

8066]

2000

CDPHE (Colorado Department of Public Health and Environment), 2000, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2000, Denver, Colorado. [SRDB Ref ID: 32102]

DOE (U.S. Department of Energy), 2000a, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, January – March 2000, Rocky Flats Field Office, Golden, 

Colorado, May. [SRDB Ref ID: 8065]

DOE (U.S. Department of Energy), 2000b, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, April - June 2000, Rocky Flats Field Office, Golden, 

Colorado, August. [SRDB Ref ID: 8067]

DOE (U.S. Department of Energy), 2000c, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, July - September 2000, Rocky Flats Field Office, Golden, 

Colorado, November. [SRDB Ref ID: 7927]

DOE (U.S. Department of Energy), 2001a, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, October – December 2000, Rocky Flats Field Office, 

Golden, Colorado, February. [SRDB Ref ID: 7934]
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 33 of 57

 

2001

CDPHE (Colorado Department of Public Health and Environment), 2001a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2001, Denver, Colorado. [SRDB Ref ID: 32103]

DOE (U.S. Department of Energy), 2001b, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, January – March 2001, Rocky Flats Field Office, Golden, 

Colorado, May. [SRDB Ref ID: 7937]

CDPHE (Colorado Department of Public Health and Environment), 2001b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Second Quarter 2001, Denver, Colorado. [SRDB Ref ID: 22176]

DOE (U.S. Department of Energy), 2001c, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, April - June 2001, Rocky Flats Field Office, Golden, 

Colorado, August. [SRDB Ref ID: 7945]

CDPHE (Colorado Department of Public Health and Environment), 2001c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Third Quarter 2001, Denver, Colorado. [SRDB Ref ID: 22177]

CDPHE (Colorado Department of Public Health and Environment), 2002a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Fourth Quarter 2001, Denver, Colorado. [SRDB Ref ID: 22178]

DOE (U.S. Department of Energy), 2002a, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, October - December 2001, Rocky Flats Field Office, 

Golden, Colorado, February. [SRDB Ref ID: 7948]

2002

CDPHE (Colorado Department of Public Health and Environment), 2002b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2002, Denver, Colorado. [SRDB Ref ID: 32104]

DOE (U.S. Department of Energy), 2002b, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, January – March 2002, Rocky Flats Field Office, Golden, 

Colorado, May. [SRDB Ref ID: 7952]

CDPHE (Colorado Department of Public Health and Environment), 2002c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Second Quarter 2002, Denver, Colorado. [SRDB Ref ID: 32108]

CDPHE (Colorado Department of Public Health and Environment), 2002d, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Third Quarter 2002, Denver, Colorado. [SRDB Ref ID: 32110]

DOE (U.S. Department of Energy), 2002c, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, July - September 2002, Rocky Flats Field Office, Golden, 

Colorado, November. [SRDB Ref ID: 7954]

DOE (U.S. Department of Energy), 2003a, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, October – December 2002, Rocky Flats Field Office, 

Golden, Colorado, February. [SRDB Ref ID: 4647]
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2003

CDPHE (Colorado Department of Public Health and Environment) 2003a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2003, Denver, Colorado. [SRDB Ref ID: 32105]

DOE (U.S. Department of Energy), 2003b, Rocky Flats Environmental Technology Site Quarterly 

Environmental Monitoring Report, January – March 2003, Rocky Flats Field Office, Golden, 

Colorado, May. [SRDB Ref ID: 8062]

CDPHE (Colorado Department of Public Health and Environment), 2003b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Second Quarter 2003, Denver, Colorado. [SRDB Ref ID: 32109]

CDPHE (Colorado Department of Public Health and Environment), 2003c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Third Quarter 2003, Denver, Colorado. [SRDB Ref ID: 22179]

CDPHE (Colorado Department of Public Health and Environment), 2004a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Fourth Quarter 2003, Denver, Colorado. [SRDB Ref ID: 32113]

2004

CDPHE (Colorado Department of Public Health and Environment), 2004b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2004, Denver, Colorado. [SRDB Ref ID: 32106]

CDPHE (Colorado Department of Public Health and Environment), 2004c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Third Quarter 2004, Denver, Colorado. [SRDB Ref ID: 32111]

2005

CDPHE (Colorado Department of Public Health and Environment), 2005a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, First Quarter 2005, Denver, Colorado. [SRDB Ref ID: 32107]

CDPHE (Colorado Department of Public Health and Environment), 2005b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, 

Information Exchange, Third Quarter 2005, Denver, Colorado. [SRDB Ref ID: 32112]
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 35 of 57

GLOSSARY

alpha emitter

Radioisotope that decays by emitting an alpha particle.

alpha particle (α)

See alpha radiation.

alpha radiation

Positively charged particle emitted from the nuclei of some radioactive elements. An alpha 

particle consists of two neutrons and two protons (a helium nucleus) and has an electrostatic 

charge of +2.

becquerel

International System unit of radioactivity equal to 1 disintegration per second; 1 curie equals 

37 billion (3.7 × 1010) Bq.

beta radiation

Charged particle emitted from some radioactive elements with a mass equal to 1/1,837 that of 

a proton. A negatively charged beta particle is identical to an electron. A positively charged 

beta particle is a positron.

curie

Traditional unit of radioactivity equal to 37 billion (3.7 × 1010) becquerels, which is 

approximately equal to the activity of 1 gram of pure 226Ra.

depleted uranium

Uranium with a percentage of 235U lower than the 0.7% found in natural uranium.

dosimeter

Device that measures the quantity of received radiation, usually a holder with radiationabsorbing filters and radiation-sensitive inserts packaged to provide a record of absorbed dose 

received by an individual. See thermoluminescent dosimeter.

dosimetry

Measurement and calculation of internal and external radiation doses.

enriched uranium

Uranium in which processing has increased the proportion of 235U to 238U to above the natural 

level of 0.7% by mass. Reactor-grade uranium is usually about 3.5% 235U; weapons-grade 

uranium contains greater than 90% 235U.

exposure

(1) In general, the act of being exposed to ionizing radiation. (2) Measure of the ionization 

produced by X- and gamma-ray photons in air in units of roentgens.

film

In the context of external dosimetry, radiation-sensitive photographic film in a light-tight 

wrapping. See film dosimeter.

film dosimeter

Package of film for measurement of ionizing radiation exposure for personnel monitoring 

purposes. A film dosimeter can contain two or three films of different sensitivities, and it can 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 36 of 57

 

contain one or more filters that shield parts of the film from certain types of radiation. When 

developed, the film has an image caused by radiation measurable with an optical 

densitometer. Also called film badge.

gamma radiation

Electromagnetic radiation (photons) of short wavelength and high energy (10 kiloelectron-volts 

to 9 megaelectron-volts) that originates in atomic nuclei and accompanies many nuclear 

reactions (e.g., fission, radioactive decay, and neutron capture). Gamma photons are identical 

to X-ray photons of high energy; the difference is that X-rays do not originate in the nucleus.

gamma ray, particle, or photon (γ)

See gamma radiation. 

isotope

One of two or more atoms of a particular element that have the same number of protons 

(atomic number) but different numbers of neutrons in their nuclei (e.g., 234U, 235U, and 238U). 

Isotopes have very nearly the same chemical properties.

nuclide

Stable or unstable isotope of any element. Nuclide relates to the atomic mass, which is the 

sum of the number of protons and neutrons in the nucleus of an atom. A radionuclide is an 

unstable nuclide.

operating area

Usually refers to a major operational work area at a site.

radiation

Subatomic particles and electromagnetic rays (photons) with kinetic energy that interact with 

matter through various mechanisms that involve energy transfer.

radioactivity

Property possessed by some elements (e.g., uranium) or isotopes (e.g., 14C) of spontaneously 

emitting energetic particles (electrons or alpha particles) by the disintegration of their atomic 

nuclei. See radionuclide. 

radionuclide

Radioactive nuclide. See nuclide. 

rem

Traditional unit of radiation dose equivalent that indicates the biological damage caused by 

radiation equivalent to that caused by 1 rad of high-penetration X-rays multiplied by a quality 

factor. The sievert is the International System unit; 1 rem equals 0.01 sievert. The word 

derives from roentgen equivalent in man; rem is also the plural.

thermoluminescent dosimeter (TLD)

Device for measuring radiation dose that consists of a holder containing solid chips of material 

that, when heated, release the stored energy as light. The measurement of this light provides 

a measurement of absorbed dose. TLDs replaced film dosimeters at essentially all U.S. 

Department of Energy sites beginning in the 1960s.
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ATTACHMENT A 

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS 

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Introduction ............................................................................................................................ 38

A.2 Measurement of Total Long-Lived Alpha Activity and Plutonium in Air ................................... 38

A.3 Atmospheric Transport Modeling............................................................................................ 40

LIST OF TABLES

TABLE TITLE PAGE

A-1 Monthly average concentrations of TLLα activity in onsite air samples, October 1964 to 

December 1971 .....................................................................................................................51

A-2 Estimated annual average concentrations of 239/240Pu in onsite air samples, 1965 to 2005..... 53

A-3 Annual average concentrations of plutonium in air for three location groups, contractor 

monitoring, 1971 to 1990........................................................................................................ 54

A-4 Comparison of 239/240Pu concentrations in onsite and offsite air as measured by CDPHE....... 55

A-5 Annual average concentrations of 239/240Pu in Denver air, 1971 to 1989 ................................. 56

A-6 Corrected annual average concentrations of 239/240Pu in air at perimeter monitoring 

stations ..................................................................................................................................57

LIST OF FIGURES

FIGURE TITLE PAGE

A-1 Location of samplers operated by contractor.......................................................................... 44

A-2 Location of computational nodes used to predict average air concentrations for industrial 

area .......................................................................................................................................45

A-3 Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in industrial area ............................................................................................................46

A-4 Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in the perimeter area...................................................................................................... 47

A-5 Locations of computational nodes used to compute annual average perimeter 

concentrations shown in Figure A-6 ....................................................................................... 48

A-6 Eastern part of industrial area, showing locations of CDPHE air monitoring stations D-1 

to D-5 .....................................................................................................................................49

A-7 Locations of offsite air samplers in 1975 ................................................................................ 50
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

A.1 INTRODUCTION

Occupational environmental dose reconstruction for RFP requires that 239/240Pu air concentrations be 

estimated for onsite locations as a function of time. Actual measurements of 239/240Pu in air for the 

RFP onsite environment are generally preferable to modeled concentrations because modeling relies 

on measurements of parameters related to source terms and meteorology that are often spatially and 

temporally averaged, which adds considerable uncertainty to estimates for particular locations or 

points in time. Further, models often cannot address all the processes or source terms that affect the 

air concentration. However, there are periods in the RFP operational history when useful 

measurements of 239/240Pu in air are not available. This attachment describes the availability of 

monitoring data and modeled estimates and addresses the suitability of each type of estimate for use 

in occupational dose reconstruction for particular periods. In addition, it provides the technical basis 

of atmospheric transport calculations that support the estimated 239/240Pu intakes.

A.2 MEASUREMENT OF TOTAL LONG-LIVED ALPHA ACTIVITY AND PLUTONIUM IN AIR

Task 4 of the Phase II Historical Public Exposures Studies on RFP (Rope et al. 1999) contains an 

in-depth historical review and compilation of air monitoring data. This attachment relies on 

conclusions from that review to determine the usefulness of onsite air monitoring data in estimating 

239/240Pu intake from environmental (outdoor) exposures.

According to Rope et al. (1999), 239/240Pu concentrations in air were not measured at RFP until 1969, 

when CDPHE began reporting onsite air concentrations. Between the start of operations in 1952 and 

1969, gross alpha activity in air was measured by the RFP contractor, but earlier data during this 

period (up to 1964) were considered by Rope et al. (1999, pp. 96–98) to be of limited value for 

assessing concentrations of long-lived alpha emitters such as 239/240Pu. Before 1960, measurements 

were not made in a way that enabled estimation of the long-lived alpha component of the gross alpha 

measurements. Therefore, there is no reliable way to estimate 239/240Pu in air before 1960 from air 

monitoring data. From 1960 to 1964, counts of gross alpha activity were made near the time of 

collection (4 hours after) and 1 week later, so that TLLα activity concentrations could be estimated. 

Estimates of 239/240Pu concentrations can be made from TLLα activity concentrations in a manner 

described later in this attachment. However, data from 1960 to 1964 were of limited value to the 

Task 4 studies because they were reported as one onsite number with the maximum and minimum 

individual count values shown. Results from individual samplers could not be obtained. Therefore, 

data from before 1964 were either not suitable or not readily available for this TBD. Due to these 

inadequacies in monitoring data during the period between 1952 and 1964, this TBD relied on 

atmospheric dispersion modeling for the Phase II study for developing estimates of 239/240Pu 

concentrations in onsite air. This section describes the Phase II model and application for the present 

purposes.

From October 1964 until December 1971, the RFP contractor reported daily TLLα activity 

concentrations in air for individual onsite samplers (Rope et al. 1999, p. 99). The samplers included 

S-1 through S-10, S-50, and S-51. The locations of the onsite samplers during this period are shown 

in the upper “1974” drawing in Figure A-1 (reproduced from Figure B-6 in Rope et al. 1999). Monthly 

average concentrations derived from these measurements, in fCi/m3 (1 × 10-15 Ci/m3

), are reproduced 

from Table B-6 in Rope et al. in Table A-1. (Note: Figures and tables appear at the end of this 

attachment.)

In 1969, CDPHE began monitoring 239/240Pu in air at the RFP (Rope et al. 1999, p. 86) near the east 

security fence. Rope et al. (1999, p. 88) used data from the CDPHE air monitoring stations to 
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

evaluate the predicted impact of contaminated soil after placement of the asphalt pad in the 903 Area. 

These measurements complement the air monitoring conducted by the RFP contractor and the Health 

and Safety Laboratory, which began monitoring air in the same vicinity (on the east security fence 

downwind of the 903 Area) in 1970 (Rope et al. 1999, p. 77).

In 1970, the RFP environmental monitoring program began to include routine monitoring of 239/240Pu in 

air (Rope et al. 1999, p. 128). However, results for 239/240Pu, rather than TLLα, were not reported in 

RFP annual environmental reports until 1973 (see the Environmental Reports section of the 

References). Table A-2 lists annual air concentrations, averaged over the onsite samplers and 

compiled from annual environmental reports through 1994 and the monthly data in Table A-1, along 

with the maximum onsite monthly measurement corresponding to that year. The units have been 

converted to femtocuries per cubic meter for consistency with Table A-1. Sampling locations are 

specified, and can be visualized from Figure A-1. The samplers were renumbered in 1975, as 

indicated in this figure. The annual average was not provided in the reports for 1977 to 1988 but was 

calculated from the monthly volume-weighted averages for each sampling location. Beginning in 

1977, measurements were not reported for all samplers, but for sampling stations with the greatest 

potential for elevated airborne radioactivity. Therefore, results after 1976 are not representative of an 

average for the RFP industrial area, but rather for the onsite areas likely to have the highest 

concentrations of 239/240Pu in air.

To estimate the 239/240Pu air concentration based on TLLα activity concentration for data from 1965 to 

1973 in Table A-2, a conversion factor was adopted from the review of available information on this 

topic in Rope et al. (1999, p. 107). Rope et al. evaluated data from the early 1970s and derived a 

least-squares best fit to the data result of 36% plutonium contribution to the TLLα. Some of the TLLα 

activity in onsite air was due to naturally occurring alpha emitters and fallout plutonium. The 

remainder could be attributed to plutonium, americium, and uranium from RFP (Rope et al. 1999). A 

conversion factor of 0.36 was assumed for converting TLLα activity concentrations from the annual 

environmental reports to 239/240Pu activity concentrations [10].

The annual environmental reports provide 95% CLs for the average annual 239/240Pu air concentration 

for RFP for 1972 to 1976 and 1989 to 1994. For these years, the standard deviation was reported as 

the 95% CLs, assuming the measurements were normally distributed. In 1977 and 1978, no standard 

deviations were reported because “they can be misleading and (their use) is considered inappropriate 

for the data in this report” (Barker et al. 1978; Bokowski et al. 1979). These two reports state that the 

sampling methods would result in “nonrandom variations in the measured concentrations,” and the 

“distribution ... would not be normal.” Standard deviations were reported for 1979 to 1988, but only by 

sampler location, and not normalized to the site average. The CLs, when reported, were based on 

counting error alone and therefore represent the minimum error that can be associated with the 

measurements. Although counting error does contribute to uncertainty in the data, the uncertainty 

associated with a given average value for the site was also a function of variability in environmental 

conditions as a function of time and location. Therefore, the reported CLs are not useful for 

estimating uncertainty associated with a site average because they would undoubtedly underestimate 

that uncertainty.

Annual environmental reports were discontinued after 1994 as a result of the change in the RFP 

mission, so sitewide measurements of 239/240Pu in air after 1994 are not as readily accessible. 

Between 1995 and July 1998, onsite ambient air concentrations of 239/240Pu were reported in RFETS 

and other monthly and quarterly monitoring reports (EG&G 1995; RMRS 1995a to 1998d). For 1995, 

an onsite average air concentration could be calculated from the reported data for approximately 

20 sampling locations, and a sitewide maximum annual average corresponding to the sampler at the 
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

location of highest concentration was also readily obtained. From 1996 to July 1998, air 

concentrations for only two samplers were reported, those samplers being at the point of highest air 

concentration based on monitoring in recent years. Therefore, the reported air concentrations for 

those years tend to be more representative of maximum concentrations rather than sitewide

averages. Annual air concentrations, averaged over all sampling locations, were calculated for 1995 

through July 1998, and are listed in Table A-2. Sitewide maximum concentrations in Table A-2 

correspond to the highest annual average concentration for any given sampler. 

After July 1998, onsite air concentrations have not been reported directly in the quarterly reports. 

However, CDPHE reported onsite concentrations in the eastern area of the industrial zone, where air 

concentrations tended to be highest (downwind of the contaminated soil area), after 1998. The 

concentrations CDPHE reported were used to estimate sitewide maximum air concentrations for 

years after 1998 and are included in Table 4-3. Special project monitoring has been carried out to 

monitor specific demolition and remediation activities. Formal reporting of this monitoring activity has 

been requested [11].

A.3 ATMOSPHERIC TRANSPORT MODELING

The atmospheric transport modeling results that were used to develop estimates of 239/240Pu intake by 

workers between 1953 and 1964 relied on application of a model developed for the offsite risk 

assessment (Rood, Grogan, and Till 1999) [12]. Application of this model for onsite predictions was 

not the original intent, and simulated concentrations are considered less reliable than measured 

concentrations for estimates of 239/240Pu intake for reasons stated in the introductory paragraph to this 

attachment. The application of this model for the Phase II Historical Public Exposures Studies 

focused on offsite rather than onsite concentrations, the latter being of interest here. However, the 

model application is such that building wake effects, a potential concern for areas close to the 

sources, are not significant for two reasons. First, releases from the Building 771 stack were not likely 

to be affected by building wakes because the 44-m stack is sufficiently high in relation to nearby 

buildings so that the plume was not significantly affected [13]. Second, all other elevated sources in 

the model were treated as area sources, such that initial dispersion was assigned, which implicitly 

accounts for the effects of building wakes [14].

Rood, Grogan, and Till (1999) described atmospheric transport modeling as follows (literature 

citations removed from quotation):

Atmospheric transport modeling performed in the Phase II studies used the Regional 

Atmospheric Transport Code for Hanford Environmental Tracking (RATCHET) model. 

Selection of RATCHET was based on a model comparison study performed for Phase 

II. In this study, five models, ranging in complexity from a simple straight-line Gaussian 

plume model (Industrial Source Complex Short Term Version 2) to a complex terrain 

model (Terrain-Responsive Atmospheric Code), were compared to tracer 

measurements taken during the 1991 Winter Validation Tracer Study. The results of this 

evaluation indicated no one model clearly outperformed the others. However, the puff 

trajectory models (RATCHET, TRIAD, and INPUFF2) generally had lower variability and 

higher correlation to observed values compared to the other models. The RATCHET 

model was chosen for these calculations because it incorporates spatially varying 

meteorological and environmental parameters. Additionally, the model includes 

modules that perform random sampling of the meteorological parameters, allowing for 

Monte Carlo analysis of uncertainty. 
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Atmospheric transport simulations were performed differently for discrete and continuous 

events. For discrete events, meteorological data for the specific days of the event were 

available. RATCHET was run using its Monte Carlo sampling features that sampled from 

distributions of basic transport parameters for each Monte Carlo trial. Transport 

parameters that were considered stochastically included wind speed, wind direction, 

mixing height, precipitation, and Monin-Obukhov scaling length. Uncertainty in the 

source term was also included in the simulation. Output consisted of n realizations of 

time-integrated concentration (TIC) and deposition at each of the 2295 computational 

nodes in the model domain (Figure 3).

Continuous events were modeled somewhat differently. Meteorological data from Rocky 

Flats for most of the assessment period were lacking. Therefore, we relied on a 

technique often used in prospective analysis and in retrospective analysis when 

historical records are lacking. This technique uses compilations of recently acquired 

meteorological data as a surrogate for past or future conditions and typically only applies 

to assessments of long-term (>1 year) dispersion conditions. We employed this 

technique for estimating annual average plutonium concentrations from routine releases 

and continuous 903 Area suspension releases using a 5-year data set from 1989 to 

1993. Uncertainty was represented using several multiplicative correction factors that 

accounted for uncertainty in the dispersion process, meteorology, and deposition-plume 

depletion.

The model domain (Figure 3) encompasses a 2200 km2 area (50 km north-south × 44 

km east-west). The domain extends 28 km south, 12 km west, 22 km north, and 32 km 

east from the RFP. Most of the Denver metropolitan area and the city of Boulder are 

included in the domain.

The domain was limited in its western extent because few receptors were present there 

during the RFP operations and most of the contaminant plumes traveled east and 

southeast of the plant.

Figure 3 from Rood, Grogan, and Till (1999) is not reproduced here because of the irrelevance of 

much of the model domain. Rather, Figure A-2 shows the model domain of relevance, which is the 

RFP industrial area. There are six nodes in the industrial area, which provides the ability to estimate 

six different air concentrations for these regions.

Discrete events in the Phase II studies were defined as those that led to releases of plutonium that 

occurred over a relatively short period, and these included releases from glovebox fires in 1957 and 

1969 and suspension of plutonium-contaminated soil from the 903 Area during unusually high-wind 

events in 1968 and 1969. Continuous releases included “routine” releases from the Building 771 

stack and Building 776 roof vents and suspension of 239/240Pu-contaminated soil from the 903 Area 

from 1964 to 1969 before the asphalt pad was in place, but those did not include the above-noted 

high-wind events. Resuspension of 239/240Pu deposited on soil from 903 Area suspension releases 

and other routine and non-routine events was included in the comprehensive evaluation of exposure 

to 239/240Pu released from RFP (Rood, Grogan, and Till 1999). A time-dependent factor approach was 

used to address the resuspension of soil contaminated by released 239/240Pu and deposited as a result 

of the continuous and discrete events. Rood, Grogan, and Till (1999, p. 32) described the source 

term characterization.
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

The aerodynamic diameter of released 239/240Pu particles is important in predicting dispersion and 

deposition and ultimately in estimating the respirable fraction of the 239/240Pu in air. The source terms 

characterized for the Phase II studies considered potential size distributions, and the predictive 

modeling addressed differential dispersion and deposition according to particle size. Therefore, the 

results of the modeling enabled prediction of the 239/240Pu concentration in air associated with 

respirable particles.

Comparisons of model output for the RFP onsite and perimeter regions to air monitoring data from 

onsite and perimeter samplers, respectively, were made to determine the adequacy of the predictive 

results in representing concentrations to which RFP workers might have been exposed. Figure A-3 

plots the annual average 239/240Pu concentrations in air as a function of time in the RFP industrial area 

from 1953 to 1990. Model-predicted concentrations represent the average of the six onsite 

computational nodes shown in Figure A-2, and are for particles less than 30-μm AED. Figure A-4 

plots annual average 239/240Pu concentrations in air as a function of time for the perimeter area of the 

Plant from 1953 through 1989. For perimeter locations, model-predicted concentrations represent the 

average of 27 computational nodes, shown in Figure A-5. The 5th-, 50th-, and 95th-percentile 

concentrations for 500 realizations for each of these model applications are shown for the period from 

1953 to 1989.

The measured data in Figure A-3 represent the average concentrations across the onsite samplers 

listed in the legend. Samplers S-1 to S-10, S-50, and S-51 were maintained by an RFP contractor 

throughout the period of interest. The annual average TLLα data from 1965 through 1972, calculated 

from the data in Table A-1, were converted to 239/240Pu concentrations for comparison to the model 

predictions. A conversion factor of 0.36 (0.36 Ci 239/240Pu per Ci TLLα) reported in Figure III-23 in 

Rope et al. (1999) was used [15]. Average concentrations from samplers S-5 to S-9 were obtained 

from Table B-10 in Rope et al. (1999), which is reproduced in Table A-3. The onsite values in this 

table tend to be slightly higher than the averages in Table A-2 because they are restricted to samplers 

S-5 to S-9 only for all years. Figure A-3 also plots the arithmetic average of measurements from 

CDPHE samplers D-3, D-4, and AP-56 at the eastern security fence of RFP (Figure A-6). The data 

from which averages were derived for these CDPHE samplers are listed in Table A-4, which was 

reproduced from Table III-4 in Rope et al. (1999).

From Figure A-3, it is clear that the modeled 50th-percentile concentrations could underpredict the 

measured concentrations, especially after about 1970. Before 1970, agreement between model 

predictions and measured concentrations is fairly good. One possible explanation for underprediction 

that does not necessarily render modeling as an underprediction of 239/240Pu intake at RFP is that 

reported 239/240Pu concentrations are often at locations of expected elevated concentrations, while the 

modeled concentrations are averages for the entire site. After 1970, the main source of plutonium to 

onsite air was resuspension of contaminated soil (Rood, Grogan, and Till 1999, p. 7). Therefore, air 

concentrations in the area of highest soil plutonium (downwind of the 903 Area) would be likely to be 

higher than the site average. Because the measured data predominantly arose from that area 

(samplers S-5 through S-9), it is likely that measured concentrations exceeded the site average. It is 

not necessarily likely, however, that an exposed individual would spend a significant amount of time in 

an area of higher 239/240Pu concentration in air. Therefore, the model might be a more reasonable 

predictor of average dose for an individual exposed to average concentrations across the site rather 

than in the areas of higher 239/240Pu concentration.

The measured data in Figure A-4 for the perimeter concentrations were from the 1971 to 1990 annual 

environmental reports prepared by RFP contractors and represent average concentrations from RFP 

contractor perimeter samplers (shown in Figure A-7 as triangular symbols). These data were 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 43 of 57

ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

corrected for contributions from background 239/240Pu because the measured values are low enough 

that fallout concentrations can contribute a significant portion of the total measurement. Yearly 

measurements of 239/240Pu in air in Denver (Rope et al. 1999, Table B-14, reproduced in Table A-5) 

were assumed to be representative of RFP background levels [16]. These levels were subtracted 

from the perimeter measurements in Table A-3 to obtain the average net perimeter 239/240Pu 

concentrations listed in Table A-6 and plotted in Figure A-4. From Figure A-4, it is clear that the 

model predictions and measured concentrations are in good agreement for these perimeter locations.

The results of these comparisons of model predictions with measured 239/240Pu concentrations support 

the following conclusions. Onsite application of the atmospheric dispersion model that was developed 

for the Phase II historical offsite exposure studies must be done with caution. Predicted average 

onsite concentrations might not adequately represent actual concentrations of interest due to the large 

spatial variation in soil and therefore air contamination at the site. While it is desirable to use 

measured concentrations from the many air samplers across the site to derive average and maximum 

values, some of the historical data to support this are not readily available or of sufficient quality. 

Therefore, it is reasonable, especially before 1970, to use the Phase II model application for 

estimating onsite average concentrations in lieu of measurement data. 
Document No. ORAUT-TKBS-0011-4 Revision No. 03 Effective Date: 09/01/2020 Page 44 of 57

ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-1. Locations of samplers operated by contractor

(Rope et al. 1999, Figure B-6). In 1975, samplers were 

renumbered and new samplers were added.

1974

1975
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-2. Location of computational nodes (circles) used to predict average air concentrations for 

industrial area. 

479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-3. Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in industrial area. Model-predicted concentrations represent the average of six onsite 

computational nodes as shown in Figure A-3 using the model described in Rood, Grogan, and Till 

(1999).

1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

1.0x10-5

1.0x10-4

1.0x10-3

1.0x10-2

1.0x10-1

1.0x100

1.0x101

1.0x102

1.0x103

Annual Average 239,240Pu Concentration 

in Air for Particles < 30 

μm (fCi m-3)

Modeled 95th percentile

Modeled 50th percentile

Modeled 5th percentile

Average of S-1 thru S-10, S-50, and S-51 TLLa converted to 239,240Pu

Average of D-3, D-4 and AP-56

Average of S-5 - S-9
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-4. Annual average 239/240Pu concentrations in air as a function of time for particles <30-μm 

AED in the perimeter area. Model-predicted concentrations represent the average of 27 

computational nodes as shown in Figure A-7 using the model described in Rood, Grogan, and Till 

(1999).

1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

1.0x10-4

1.0x10-3

1.0x10-2

1.0x10-1

1.0x100

1.0x101

1.0x102

1.0x103

Annual Average 239,240Pu Concentration 

in Air for Particles < 30 

μm (fCi m-3)

Modeled 95th percentile

Modeled 50th percentile

Modeled 5th percentile

Average of Perimeter Stations - Background
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-5. Locations of computational nodes (squares) used to compute annual average perimeter 

concentrations shown in Figure A-6. 

479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-6. Eastern part of industrial area, showing locations of CDPHE air monitoring stations 

D-1 to D-5 (Rope et al. 1999, Figure III-13). Sampler AP-56 is believed to be north of Central 

Avenue near the security fence.
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Figure A-7. Locations of offsite air samplers in 1975 (Rope et al. 1999, Figure B-4).
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Table A-1. Monthly average concentrations (fCi/m3) of TLLα activity in onsite air samples, October 

1964 to December 1971.

a

Month S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-50 S-51

Oct 64 2 6 2 4 4 3 3 11 6 4 No data No data

Nov 64 1 2 6 1 2 2 2 16 3 2 No data No data

Dec 64 2 3 4 2 7 4 3 79 4 3 No data No data

Jan 65 2 2 11 3 7 2 2 8 3 2 No data No data

Feb 65 3 2 2 4 4 4 3 4 2 3 No data No data

Mar 65 5 3 3 5 3 5 2 2 3 3 No data No data

Apr 65 5 3 2 2 2 3 3 5 2 2 No data No data

May 65 3 13 1 3 4 5 3 4 2 3 No data No data

Jun 65 4 2 2 2 4 5 2 8 2 2 No data No data

Jul 65 4 2 2 2 3 6 2 9 1 3 No data No data

Aug 65 4 1 2 3 3 4 2 5 2 3 No data No data

Sep 65 5 3 3 3 7 5 0 5 2 4 No data No data

Oct 65 3 3 3 1 2 4 2 3 3 2 No data No data

Nov 65 10 3 3 2 4 4 2 9 3 4 No data No data

Dec 65 4 7 7 6 14 13 5 7 4 9 No data No data

Jan 66 11 6 4 2 8 4 3 12 6 14 No data No data

Feb 66 3 2 3 5 6 2 1 11 3 4 No data No data

Mar 66 4 2 4 3 3 3 2 11 5 3 No data No data

Apr 66 3 2 3 4 4 4 2 6 3 2 No data No data

May 66 4 4 4 3 6 5 5 5 7 7 No data No data

Jun 66 7 5 4 2 3 13 8 12 6 8 No data No data

Jul 66 7 6 4 4 6 6 5 11 7 6 No data No data

Aug 66 15 7 4 12 7 11 8 13 8 6 No data No data

Sep 66 28 8 9 12 18 16 5 10 7 8 No data No data

Oct 66 11 4 4 7 8 8 9 10 7 4 No data No data

Nov 66 7 2 3 16 8 6 6 13 5 3 No data No data

Dec 66 7 4 5 14 10 12 4 8 8 6 No data No data

Jan 67 8 4 7 15 13 7 6 22 23 8 No data No data

Feb 67 5 6 6 22 8 8 13 38 6 4 No data No data

Mar 67 6 1 5 11 7 8 5 9 5 3 No data No data

Apr 67 3 3 6 6 10 7 3 11 5 7 No data No data

May 67 9 4 7 8 9 12 8 9 6 5 No data No data

Jun 67 10 5 8 13 14 11 17 18 5 5 No data No data

Jul 67 15 5 7 8 11 14 28 19 9 3 No data No data

Aug 67 27 6 15 10 11 17 28 26 10 12 No data No data

Sep 67 5 3 3 6 4 14 14 22 4 5 No data No data

Oct 67 5 3 7 7 5 15 24 99 No data 7 No data No data

Nov 67 6 5 10 6 4 9 8 49 No data 7 No data No data

Dec 67 9 7 17 7 3 3 9 92 No data 4 No data No data

Jan 68 8 4 12 5 6 3 8 29 No data 5 No data No data

Feb 68 15 9 23 12 7 6 10 33 No data 11 No data No data

Mar 68 14 18 22 8 9 17 11 116 No data 28 No data No data

Apr 68 16 11 13 9 6 27 31 182 No data 10 No data No data

May 68 8 9 17 10 7 21 70 155 No data 8 No data No data

Jun 68 6 6 8 12 4 51 68 110 No data 18 No data No data

Jul 68 5 4 7 4 4 14 14 31 No data 3 No data No data

Aug 68 9 6 8 5 7 9 10 17 No data 4 No data No data

Sep 68 6 6 7 5 5 4 9 50 No data 3 No data No data

Oct 68 12 7 8 6 4 11 19 33 No data 3 7 11
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Month S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-50 S-51

Nov 68 7 4 6 3 7 9 6 168 No data 4 4 2

Dec 68 11 6 4 8 6 6 20 357 No data 3 11 3

Jan 69 10 6 9 7 10 15 127 1525 No data 3 7 5

Feb 69 6 4 8 5 5 4 23 129 No data 3 4 3

Mar 69 7 4 3 5 4 2 4 208 No data 2 5 3

Apr 69 7 3 5 3 6 3 22 148 4 4 5 6

May 69 5 11 9 9 9 17 21 28 10 6 9 6

Jun 69 4 4 7 4 4 7 9 68 4 4 7 3

Jul 69 15 7 7 7 4 20 7 20 4 4 11 6

Aug 69 4 6 5 6 5 7 7 22 5 3 6 9

Sep 69 6 6 5 5 6 5 6 19 4 3 5 5

Oct 69 6 3 5 18 3 5 3 12 2 3 3 3

Nov 69 3 2 4 5 4 3 2 12 2 3 4 4

Dec 69 5 4 5 7 4 2 4 32 7 5 4 4

Jan 70 3 2 4 4 4 3 3 12 3 4 2 3

Feb 70 2 4 5 4 3 4 13 33 3 6 2 7

Mar 70 3 4 4 15 3 5 4 10 4 4 3 5

Apr 70 10 5 5 7 9 7 5 7 2 3 5 3

May 70 9 4 5 3 4 4 2 10 1 4 4 4

Jun 70 14 7 12 9 57 13 7 10 4 13 7 10

Jul 70 7 5 1 3 2 2 2 4 3 3 4 4

Aug 70 3 4 2 3 2 4 10 4 3 4 2 5

Sep 70 2 6 6 3 3 3 3 5 3 4 4 4

Oct 70 5 3 5 4 3 4 2 5 3 4 3 4

Nov 70 2 6 3 3 5 4 1 3 2 2 4 2

Dec 70 3 4 3 3 3 3 6 5 2 3 4 2

Jan 71 4 4 3 2 3 4 7 5 4 4 4 4

Feb 71 3 4 2 4 4 3 6 7 4 5 3 5

Mar 71 5 4 4 5 3 3 8 8 4 5 8 4

Apr 71 4 4 5 7 4 3 3 26 4 5 5 5

May 71 5 4 5 3 4 6 4 9 4 5 5 4

Jun 71 4 3 4 5 5 4 4 10 4 7 7 4

Jul 71 4 3 5 4 4 12 3 12 3 2 4 2

Aug 71 4 4 6 4 3 3 4 8 4 3 9 4

Sep 71 5 3 6 3 3 3 2 6 3 4 6 3

Oct 71 5 4 4 3 6 3 2 12 2 5 7 5

Nov 71 3 4 6 3 5 5 3 10 2 4 5 4

Dec 71 4 5 4 3 3 4 4 6 3 4 5 4

a. Source: Rope et al. (1999, Table B-6), reconstructed from daily measurements.
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Table A-2. Estimated annual average concentrations (fCi/m3) of 239/240Pu in onsite air samples, 1965 

to 2005.

a

Year Sampling locationb

Type of 

measurement

Conversion 

factor to 

239/240Puc

Annual 

average air 

concentration 

(fCi/m3)

Maximum air 

concentrationd

(fCi/m3)

1965 S1–S10 TLLα 0.36 1e 2e

1966 S1–S10 TLLα 0.36 2e 4e

1967 S1–S10 TLLα 0.36 4e 12e

1968 S1–S8, S10 TLLα 0.36 7e 38e

1969 S1–S10, S50–S51 TLLα 0.36 8e 67e

1970 S1–S10, S50–S51 TLLα 0.36 2e 3e

1971 S1–S10, S50–S51 TLLα 0.36 2e 4e

1972 S1–S10, S50–S51 TLLα 0.36 <2.1 3.9

1973 S1–S10, S50–S52 TLLα 0.36 <2.2 <3.9

1973 S1–S10, S50–S52 Pu-239/240 1 <1.2 <6.5

1974 S1–S10, S50–S52 Pu-239/240 1 0.6 3.2

1975 S1–S10, S22, S50–S52, Af-83, 

Ac-84

Pu-239/240 1 <0.2 1.0

1976 S1–S24 Pu-239/240 1 0.2 1.4

1977 S1–S24 Pu-239/240 1 0.3f 0.6

1978 S5–S9, S19–S21 Pu-239/240 1 0.3f 0.9

1979 S2, S5–S9,S15–S16, S19–S21 Pu-239/240 1 0.2f 0.5

1980 S5–S9, S16, S19–S21 Pu-239/240 1 0.2f 0.5

1981 S5–S9, S16, S19–S21 Pu-239/240 1 0.2f 0.5

1982 S5–S9, S16, S19–S21 Pu-239/240 1 0.3f.g 0.5

1983 S5–S9 Pu-239/240 1 0.2f.g 0.4

1984 S5–S9 Pu-239/240 1 0.3f.g 0.6

1985 S5–S9 Pu-239/240 1 0.2f.g 0.4

1986 S5–S9 Pu-239/240 1 0.3f.g 0.5

1987 S5–S9 Pu-239/240 1 0.7f.g 1.2

1988 S5–S9 Pu-239/240 1 0.5f.g 0.7

1989 S5–S9 Pu-239/240 1 0.4 0.5

1990 S1–S24, S88 Pu-239/240 1 0.1 0.9

1991 S1–S25 Pu-239/240 1 0.1 1.2

1992 S1–S25 Pu-239/240 1 0.1 0.6

1993 S3–S25 Pu-239/240 1 0.1 0.4

1994 S3–S25 Pu-239/240 1 0.1 0.4

1995h S005–S007, S009, S101-104, S106, 

S107, S109, S110, S112, S116, 

S119, S121, S123, S202–S206, 

S208, S211

Pu-239/240 1 0.02 0.2

1996h S007, S107 Pu-239/240 1 0.08 0.08

1997h S007, S107 Pu-239/240 1 0.05 0.07

1998h,i S007, S107 Pu-239/240 1 0.080 0.1

1999j,k D-1,D-3 Pu-239/240 1 0.07 0.1

2000j D-1,D-3 Pu-239/240 1 0.08 0.1

2001j D-1,D-3 Pu-239/240 1 0.08 0.2

2002j D-1,D-3 Pu-239/240 1 0.03 0.05

2003j D-1,D-3 Pu-239/240 1 0.09 0.2
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Year Sampling locationb

Type of 

measurement

Conversion 

factor to 

239/240Puc

Annual 

average air 

concentration 

(fCi/m3)

Maximum air 

concentrationd

(fCi/m3)

2004j D-1 Pu-239/240 1 0.03 0.03

2005j,l D-1 Pu-239/240 1 0.1 0.1

a. Based on measurement data provided in Table A-1, RFP annual environmental reports, RFETS monthly and quarterly 

monitoring reports, and CDPHE quarterly environmental surveillance reports (Environmental Reports section of the 

References), unless otherwise noted.

b. Refer to Figure A-1 for samplers through 1994; after 1994, see monthly and quarterly monitoring reports for maps.

c. Based on Rope et al. (1999, pp. 107–111). 

d. The maximum monthly concentration at any one sampling location.

e. Calculated from data in Table A-1.

f. Calculated by averaging reported annual volume-weighted average concentration for each sampler.

g. Results only reported for samplers in area of higher measured plutonium air concentrations for RFP.

h. Sources: Quarterly environmental monitoring reports (EG&G 1995; RMRS 1995a, 1995b, 1996a, 1996b, 1996c, 1998b, 

1998c). 

i. Based on data collected January through July 1998.

j. Sources: CDPHE quarterly environmental surveillance reports (CDPHE 2000 to 2005b).

k. Based on last 3 quarters only.

l. Based on first 2 quarters only.

Table A-3. Annual average concentrations (fCi/m3) of 

plutonium in air for three location groups, contractor 

monitoring, 1971 to 1990a

. 

Year Onsiteb Perimeter Community

1971 No sampler 0.26 No sampler

1972 No sampler 0.14 No sampler

1973 0.274 0.05 0.26

1974 0.892 0.058 0.34

1975 0.517 0.037 0.031

1976 0.698 0.015 0.013

1977 0.393 0.038 0.037

1978 0.446 0.06 0.06

1979 0.278 0.02 0.02

1980 0.252 0.01 0.01

1981 0.287 0.018 0.019

1982 0.244 0.005 0.006

1983 0.226 0.003 0.007

1984 0.257 0.005 0.005

1985 0.235 0.002 0.002

1986 0.225 0.005 0.003

1987 0.639 0.005 0.003

1988 0.529 0.003 0.002

1989 0.363 0.001 0.001

1990 0.102 0.002 0.001

a. Obtained from RFP contractor annual reports by Rope et al. (1999, 

Table B-10); data are plotted as a line chart in Chapter III.

b. Onsite samples are the average of locations S-5, S-6, S-7, S-8, and S-9, 

as numbered in 1975. 
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Table A-4. Comparison of 239/240Pu concentrations (fCi/m3) in onsite and offsite air as measured by 

CDPHE.

a

Onsite

Location 1969 1970 1971 1972 1973 1974

D-1 No data 0.29 0.31 1.44 0.74 0.44

D-2 No data 0.37 0.34 0.69 0.62 0.73

D-3 No data 6.29 10.29 4.47 2.87 3.77

D-4 No data 2.21 7.34 5.48 4.63 1.33

APC-56 2.73 1.25 1.77 2.28 0.28 0.43

Onsite averageb 2.73 2.08 4.01 2.87 1.83 1.34

Offsite (metro)

Location 1969 1970 1971 1972 1973 1974

D-5 (SE boundary) No data 0.16 0.13 0.12 0.10 0.10

APC-2 Denver (EPA data)c 0.070 0.077 0.066 0.040 0.015 0.049

APC-15 Arvada No data 0.16 <0.08 0.06 <0.06 0.25

APC-16 Golden 0.08 <0.11 0.08 <0.06 <0.06 <0.08

APC-19 Boulder No data 0.13 <0.07 <0.05 <0.06 <0.06

APC-22 Longmont 0.08 0.12 0.07 <0.02 <0.05 <0.1

Offsite (metro) averageb 0.08 0.13 0.08 0.06 0.06 0.12

Offsite (remote)

Location 1969 1970 1971 1972 1973 1974

APC-29 Durango No data No data No data <0.12 <0.02 <0.05

APC-42 Fort Collins No data No data No data <0.04 <0.08 0.14

APC-81 Walsenburg No data No data No data 0.07 <0.06 0.38

APC-108 Rangely No data No data No data 0.1 <0.08 0.13

Offsite (remote) averagec No data No data No data 0.08 0.06 0.18

a. Source: Rope et al. (1999, Table III-4).

b. Averages in this table are arithmetic averages of the annual averages from each station.

c. Lower minimum detectable concentration for EPA data (0.001 compared to 0.08 for APC-# stations and

0.03 for D-# stations).
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Table A–5. Annual average concentrations (fCi/m3) of 239/240Pu in Denver 

air, 1971 to 1989.

a

Year Average 5th percentile 95th percentile

Method of 

determinationb

1971 6.6E−2 5.3E−2 7.9E−2 M

1972 4.0E−2 3.2E−2 4.8E−2 M

1973 1.5E−2 1.2E−2 1.8E−2 M

1974 4.9E−2 3.9E−2 5.9E−2 M

1975 3.1E−2 2.5E−2 3.7E−2 M

1976 1.1E−2 9.0E−3 1.3E−2 M

1977 3.6E−2 2.8E−2 4.0E−2 M

1978 4.8E−2 3.8E−2 5.7E−2 M

1979 1.2E−2 9.3E−3 1.4E−2 M

1980 7.6E−3 3.8E−3 1.1E−2 M

1981 1.6E−2 3.8E−3 1.1E−2 N

1982 2.3E−3 8.0E−3 2.4E−2 N

1983 1.3E−3 6.5E−4 2.0E−3 M

1984 1.0E−3 5.0E−4 1.5E−3 M

1985 4.0E−3 2.3E−3 6.8E−3 M

1986 2.5E−3 1.2E−3 3.7E−3 M

1987 6.0E−4 3.0E−4 9.0E−4 M

1988 1.0E−4 5.0E−5 1.5E−4 M

1989 7.0E−4 3.5E−4 1.0E−3 M

a. Source: Rope et al. (1999, Table B-14). 

b. M = average of values measured by the Public Health Service or EPA in Denver for 

that year. See Rope et al. (1999, Figure III-7) and associated text for additional 

discussion.
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ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS (continued)

Table A-6. Corrected annual average concentrations of 

239/240Pu in air at perimeter monitoring stations (fCi/m3

). 

Year

Pu-239/240 

concentrationa

Net Pu-239/240 

concentrationb

1971 2.60E−01 1.94E−01

1972 1.40E−01 1.00E−01

1973 5.00E−02 3.50E−02

1974 5.80E−02 9.00E−03

1975 3.70E−02 6.00E−03

1976 1.50E−02 4.00E−03

1977 3.80E−02 2.00E−03

1978 6.00E−02 1.20E−02

1979 2.00E−02 8.00E−03

1980 1.00E−02 2.40E−03

1981 1.80E−02 2.00E−03

1982 5.00E−03 2.70E−03

1983 3.00E−03 1.70E−03

1984 5.00E−03 4.00E−03

1985 2.00E−03 0.00E+00c

1986 5.00E−03 2.50E−03

1987 5.00E−03 4.40E−03

1988 3.00E−03 2.90E−03

1989 1.00E−03 3.00E−04

1990 2.00E−03 2.00E−03

a. Source: Table A-3.

b. The net concentration is the concentration in the second column minus 

the corresponding average background value reported in Table A-5.

c. Average background measurement (Table A-5) exceeded measured 

perimeter value.