ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 50

Document Title:

Y-12 National Security Complex – 

Occupational Environmental Dose

Document Number: ORAUT-TKBS-0014-4 

Revision: 01

Effective Date: 07/20/2006

Type of Document: TBD

Supersedes: Revision 00

Subject Expert: William E. Murray

Document Owner

Approval: Signature on File Approval Date: 06/23/2006

William E. Murray, TBD Team Leader

Approval: Signature on File Approval Date: 06/23/2006

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 06/22/2006

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 07/19/2006

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 07/20/2006

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 2 of 50

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

12/05/2003 00 New document to establish Occupational Environmental Dose, 

Section 4. First approved issue. Initiated by William E. Murray.

05/20/2004 00 PC-1 Corrects 3rd column on page 46, dose rate excluding background 

column from mrem h-1 to μrem h-1. Adds grid lines to Table D-7. 

First approved page change revision. Initiated by William E. Murray.

Approval:

William E. Murray, TBD Team Leader

Signature on File 05/17/2004

Task 3 Manager, Judson Kenoyer, Task 3, Manager

Signature on File 05/17/2004

Richard E. Toohey, Project Director

Signature on File 05/19/2004

James W. Neton, OCAS Health Science Administrator

Signature on File 05/20/2004

09/09/2004 00 PC-2 Corrects last column on page 11. Heading of last column changed 

from μCi cm-3 to μ g cm-3 . Second approved page change revision. 

Initiated by William E. Murray.

Approval: 

Document Owner, William E. Murray, TBD Team Leader

Signature on File 09/08/2004

Task 3 Manager, Judson Kenoyer, Task 3, Manager

Signature on File 08/27/2004

Richard E. Toohey, Project Director

Signature on File 08/30/2004

James W. Neton, Associate Director for Science

Signature on File 09/09/2004

10/11/2005 00 PC-3 Page change initiated to incorporate the definition of U.S.C. on page 

5 and details for the definition of a DOE facility on page 6. No 

sections were deleted. Third approved page change revision. 

Retraining is not required. Initiated by William E. Murray.

Approval:

William E. Murray, TBD Team Leader

Signature on file 10/06/2005

Judson L. Kenoyer, Task 3 Manager

Signature on File 10/04/2005

Richard E. Toohey, Project Director

Signature on File 10/04/2005

James W. Neton, Associate Director for Science

Signature on File 10/11/2005
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 3 of 50

07/20/2006 01 Revision initiated to incorporate definitions and directions for dose 

reconstruction for non-presumptive cancers that are excluded from 

the 1943 through 1947 Special Exposure Cohort. Environmental 

concentrations in Tables D1 through D6 for the years 1943 through 

1947 were marked as ‘Reserved’. Approved issue of Revision 01. 

This revision results in no change to the assigned dose and no PER 

is required. Training required: As determined by Task Manager. 

Initiated by William E. Murray.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 4 of 50

TABLE OF CONTENTS

SECTION TITLE

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

PAGE

6

4.1 Introduction ..............................................................................................................................8

4.1.1 Purpose.........................................................................................................................9

4.1.2 Scope............................................................................................................................9

4.2 Ambient Air Monitoring at Y-12 .............................................................................................. 10

4.2.1 Chronology of Ambient Air Monitoring Activities ..........................................................10

4.3 Approach for Estimating On Site Air Concentrations .............................................................. 17

4.3.1 Usability of Air Monitoring Data ...................................................................................17

4.3.2 Empirical Chi/Q (χ/Q) Approach for Estimating Air Concentrations.............................. 18

4.3.3 Air Concentrations by Location (Chi) ...........................................................................19

4.3.4 Release Estimates (Q) ................................................................................................19

4.3.5 Correlation of Air Concentrations with Releases..........................................................24

4.3.6 Estimating Chi/Q for Y-12 Stations ..............................................................................27

4.4 Estimation of Air Concentrations ............................................................................................ 29

4.5 Occupational External Dose................................................................................................... 30

4.5.1 Data Availability...........................................................................................................31

4.5.2 Range of Exposures from Aerial Surveys ....................................................................31

4.5.3 Results of 1987 Scoping Survey..................................................................................32

4.5.4 Estimated External Exposures for Y-12 Workers.........................................................33

References ........................................................................................................................................35

Glossary ............................................................................................................................................41

ATTACHMENT D, OCCUPATIONAL ENVIRONMENTAL DOSE ......................................................42
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LIST OF TABLES

TABLE TITLE

4.1.2-1 Summary of air monitoring data from stations at and surrounding the Y-12 

facility..................................................................................................................................

PAGE

11

4.1.2-2 Availability of uranium air concentration data measured at the twelve Y-12 

air monitoring stations ......................................................................................................... 16

4.2.3-1 Annual average air concentrations and estimated Chi/Q values for Y-12 

Station 2..............................................................................................................................20

4.2.3-2 Annual average air concentrations and estimated Chi/Q values for Y-12 

Station 4..............................................................................................................................21

4.2.3-3 Annual average air concentrations and estimated Chi/Q values for Y-12 

Station 8..............................................................................................................................22

4.2.3-4 Annual average air concentrations and estimated Chi/Q values for Y-12 

Station 12............................................................................................................................23

4.2.4-1 Compiled annual uranium release estimates....................................................................... 27

4.2.4-1 Compiled annual uranium release estimates....................................................................... 28

4.4.4-1 External environmental dose equivalent rates outside buildings on Y-12 site 

from 1948-2002Compiled annual uranium release estimates.............................................. 33 

D-1 Calculated 234/235U and 238U air concentrations and intakes for Station 2 ............................. 44

D-2 Calculated 234/235U and 238U air concentrations and intakes for Station 4 ............................. 45

D-3 Calculated 234/235U and 238U air concentrations and intakes for Station 8 ............................. 46

D-4 Calculated 234/235U and 238U air concentrations and intakes for Station 12 ........................... 47

D-5 Site wide 234/235U and 238U air concentrations and Intakes based on average 

air concentrations for Stations 2, 4, 8 and 12 ...................................................................... 48

D-6 Maximum 234/235U and 238U air concentrations and intakes................................................... 49

D-7 External dose rates outside buildings on Y-12 site .............................................................. 50

LIST OF FIGURES

FIGURE TITLE

4.1.2-1 Locations of ORNL Perimeter Air Monitoring (PAM) Stations ..............................................

PAGE

13

4.1.2-2 Location of Station 40 incorporated into the ORNL Perimeter Air Monitoring 

(PAM) network in 1983........................................................................................................ 15

4.1.2-3 Locations of the twelve Y-12 perimeter air monitoring stations............................................ 16

4.2.4-1 Distribution of release estimates for the Y-12 facility ........................................................... 24

4.2.5-1 Plot of annual total uranium air concentration measured at Station 2 versus 

estimated uranium releases ................................................................................................ 25

4.2.5-2 Plot of annual total uranium air concentration measured at Station 4 versus 

estimated uranium releases ................................................................................................ 25

4.2.5-3 Plot of annual total uranium air concentration measured at Station 8 versus 

estimated uranium releases ................................................................................................ 26

4.2.5-4 Plot of annual total uranium air concentration measured at Station 12 

versus estimated uranium releases..................................................................................... 26

4.3-1 Locations of Y-12 perimeter air monitoring stations............................................................. 29

4.3-2 Distribution of 234/235U and 238U release estimates for the years 1985 through 

1995....................................................................................................................................30
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 6 of 50

ACRONYMS AND ABBREVIATIONS

ASER Annual Site Environmental Report

Bq becquerel

CEDR Comprehensive Epidemiologic Data Resource

Ci curie 

cm centimeter

DOE Department of Energy

DU Depleted Uranium

EPA Environmental Protection Agency

EU Enriched Uranium

FP Fission products

g gram

GM Geometric mean

GSD Geometric standard deviation

h hour

kg kilogram

LAM Local area monitoring

m meter

MMES Martin Marietta Energy Systems 

NESHAP National Emission Standards for Hazardous Pollutants

ORAU Oak Ridge Associated Universities

ORDR Oak Ridge Dose Reconstruction

ORGDP Oak Ridge Gaseous Diffusion Plant

ORNL Oak Ridge National Laboratory

ORO Oak Ridge Operations

ORR Oak Ridge Reservation

OSTI Office of Scientific and Technical Information

PAM Perimeter air monitoring

RAM Remote air monitoring

SEC Special Exposure Cohort

TDEC Tennessee Department of Environment and Conservation

TRU Transuranics

U.S.C. United States Code

Y-12 Y-12 National Security Complex
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 7 of 50

y Year

μCi microcurie

μg microgram

μR microroentgen
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 8 of 50

4.1 INTRODUCTION

Technical basis documents and site profile documents are general working documents that provide 

guidance concerning the preparation of dose reconstructions at particular sites or categories of sites. 

They will be revised in the event additional relevant information is obtained about the affected site(s). 

These documents may be used to assist the National Institute for Occupational Safety and Health 

(NIOSH) in the completion of the individual work required for each dose reconstruction.

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility 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 Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 (42 

U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally derived radiation 

exposures at the facility in its dose reconstructions for employees at DOE facilities, including radiation 

exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and external 

dosimetry monitoring results are considered valid for use in dose reconstruction. No efforts are made 

to determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationally 

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation 

guidelines (nor the dose reconstruction regulation) define “performance of duty” for DOE employees 

with a covered cancer or restrict the “duty” to nuclear weapons work.

• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 9 of 50

4.1.1

The purpose of this TBD is to describe the occupational exposure monitoring program at the Y-12 

Plant (now the Y-12 National Security Complex). This document provides historical and current 

monitoring data to be used in reconstructing internal and external environmental doses for 

unmonitored workers.

Purpose

4.1.2

The Y-12 Plant, operated by BWXT Y-12, L.L.C. and its predecessors, has played an important role in 

the development of the U.S. nuclear weapons program. Operations at the Y-12 Plant have evolved 

from the separation and enrichment of uranium to the manufacture and assembly of nuclear weapons 

components to stockpile stewardship and maintenance. This TBD is part of the overall Y-12 Plant 

Site Profile, which describes plant facilities and processes, historical information, and environmental 

data in relation to dose reconstruction for Y-12 workers. It contains supporting documentation to 

assist in the reconstruction of occupational environmental internal and external doses from these 

activities.

Scope

The methods and concepts of measuring environmental internal and external exposures to workers 

have evolved since the beginning of operations at the Y-12 Plant. An objective of this document is to 

provide supporting technical data to evaluate occupational environmental internal and external doses 

that can reasonably be associated with worker radiation exposures covered by the EEOICPA 

legislation. In addition, this document presents the technical basis of methods used to prepare Y-12 

worker dose information for input to the NIOSH IREP (Interactive RadioEpidemiological Program) 

computer code. 

The occupational environmental dose received by unmonitored workers is limited to exposures 

received while outside buildings and within the perimeter of the Y-12 National Security Complex. 

Buildings and other operational units occupy the vast majority of the land area at Y-12. This 

assessment will quantify exposure for unmonitored workers who either work outdoors or otherwise 

spend time outside buildings. Based on the exposure assessment, the two exposure pathways are:

1. Inhalation of uranium in ambient air due to operational releases, and 

2. Direct external radiation from radionuclides in soils and outdoor surfaces, as well as shine 

from buildings and operational units.

Due to the complexity of the terrain surrounding Y-12 and the release mechanisms from the 

production facilities compounded by the limited dispersion distances, traditional dispersion and 

transport models were considered unsuitable. An empirical approach based on the limited ambient air 

monitoring at Y-12 was used to estimate uranium air concentrations. This approach used the annual 

release estimates independently reconstructed by previous studies to generate annual air 

concentrations for four locations within Y-12.

Based on the findings and recommendations of NIOSH and the Advisory Board on Radiation and 

Worker Health, the Secretary of Health and Human Services has determined that for the time period 

from March 1943 through December 1947, the only radiological exposures at Y-12 for which dose can 

be reconstructed are that those that resulted from occupational medical x-rays. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 10 of 50

External exposures were estimated using the results of a comprehensive radiological scoping survey 

(Foley and Carrier 1990). The analysis of the results from the scoping survey generated a statistical 

range of exposure values.

4.2 AMBIENT AIR MONITORING AT Y-12

A review of the history of environmental monitoring was conducted of the historical ambient air 

monitoring data at Y-12. The quality of collected data was then evaluated to assess its usability for 

the purposes of evaluating intakes by workers. The review identified likely sources of information for 

ambient air monitoring data for both the Oak Ridge Reservation (ORR) and Y-12 . Relevant reports 

were identified from a number of libraries including the:

• Comprehensive Epidemiologic Data Resource (CEDR) maintained by the U.S Department of 

Energy (DOE),

• Energy Citations Database, developed by the DOE, Office of Scientific and Technical 

Information (OSTI),

• Oak Ridge Associated Universities (ORAU),

• Oak Ridge National Laboratory (ORNL),

• Oak Ridge Annual Site Environmental Reports (ASER), and

• DOE Oak Ridge Operations (ORO) Public Reading rooms.

In addition, discussions with persons familiar with the environmental monitoring activities at Y-12 and 

the Oak Ridge Reservation were conducted to identify other likely sources of information. 

4.2.1

As the Y-12 facility has been operational for many years, there is no single source of ambient air 

monitoring information. This section presents a brief summary of ambient air monitoring activities 

specific to Y-12. No information on ambient air monitoring prior to 1959 was identified that was useful 

for this section. A detailed summary of air monitoring data including the source of information, the 

period of coverage, the type of available data, and the monitoring locations is presented in Table 

4.1.2-1.

Chronology of Ambient Air Monitoring Activities

1959–1970: Applied Health Physics and Safety Reports

A series of Applied Health Physics Reports were identified that were published by the Health Physics 

Division of the ORNL. These reports were issued on a quarterly basis (entitled “Environmental Levels 

of Radioactivity for the Oak Ridge Area”) and summarized in annual reports (“Applied Health Physics 

and Safety Annual Reports”). Data collected by the team may have been from either source (or both) 

as not all reports were readily available. The air concentrations presented in these reports were 

collected from a system of air monitoring stations established and maintained by ORNL. These 

stations were used to provide data in determining the dispersal of contamination should a major 

incident occur. A review of the data presented in these reports indicates that the purpose of these 

stations was to monitor the concentrations of fission products from operations at ORNL.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

07/20/2006 Page 11 of 50

Table 4.1.2-1. Summary of air monitoring data from stations at and surrounding the Y-12 facility. 

Year Reference

Off site health physics stations1 Y-12 on site air monitoring stations1

Activity/fission 

products Gross α Gross β 

Uranium 

isotopes2 Gross α Gross β 

Uranium 

isotopes2

Total uranium 

activity (μCi cm-3)

Total uranium 

mass (μ g cm-3)

1959 Abee 1960a HP-12 — — — — — — — —

1960 Abee 1960b, 

Abee 1961, 

ORNL 1960

HP-12 — — — — — — — —

1961 ORNL 1962 HP-12 — — — — — — — —

1962 ORNL 1963 HP-32 — — — — — — — —

1963 ORNL 1964a, 

ORNL 1964b

HP-32 — HP-32 — — — — — —

1964 ORNL 1965a, 

ORNL 1965b

— — HP-32 — — — — — —

1965 ORNL 1966b HP-32 HP-32 HP-32 — — — — — —

1966 ORNL 1967c, 

ORNL 1967a

HP-32 HP-32 HP-32 — — — — — —

1967 ORNL 1968c, 

ORNL 1968a

HP-32 HP-32 HP-32 — — — — — —

1968 ORNL 1969a, 

ORNL 1969b, 

ORNL 1969c

HP-32 HP-32 HP-32 — — — — — —

1969 ORNL 1969d, 

ORNL 1969e, 

ORNL 1970

HP-32 HP-32 HP-32 — — — — — —

1970 ORNL 1971 HP-32 — — — — — — — —

1971 UCC 1972 — HP-32 HP-32 — — — — — —

1972 UCC 1973 — HP-32 HP-32 — — — — — —

1973 UCC 1974 — HP-32 HP-32 — — — — — —

1974 UCC 1975 — HP-32 HP-32 — — — — — —

1975 UCC 1976 — HP-32 HP-32 PAM 

Composite3

— — — — —

1976 UCC 1977 — HP-32 HP-32 PAM 

Composite3

— — — — —

1977 UCC 1978 — HP-32 HP-32 PAM 

Composite3

— — — — —

1978 UCC 1979 — HP-32 HP-32 PAM 

Composite3

— — — — —

1979 UCC 1980 — HP-32 HP-32 PAM 

Composite3

— — — — —

1980 UCC 1981 — HP-32 HP-32 PAM 

Composite3

— — — — —

1981 UCC 1982 — HP-32 HP-32 PAM 

Composite3

— — — — —

1982 UCC 1983 — HP-32 HP-32 PAM 

Composite3

— — — — —

1983 MMES 1984 — HP-32 and HP40HP-32 and HP40PAM 

Composite3

— — — Y-12 Stations:

1 -11

—

1984 MMES 1985 — Station 40 Station 40 PAM 

Composite3

— — — Y-12 Stations:

1 -11

—
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

07/20/2006 Page 12 of 50

Table 4.1.2-1. (Continued)

Year Reference

Off site health physics stations1 Y-12 on site air monitoring stations1

Activity/fission 

products Gross α Gross β 

Uranium 

isotopes2 Gross α Gross β 

Uranium 

isotopes2

Total uranium 

activity (μCi cm-3)

Total uranium 

mass (μ g cm-3)

1985 MMES 1986 — Station 40 Station 40 PAM 

Composite3

Y-12 Stations:

1 -11

Y-12 Stations:

1 -11

Y-12 Stations:

1 –11

— —

1986 DOE 1987a, DOE 

1987b

— Station 40 Station 40 Station 40 Y-12 Stations:

1 -11

Y-12 Stations:

1 -11

Y-12 Stations:

1 -11

— —

19874 DOE 1988a, DOE 

1988b

— Station 40 Station 40 Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

1988 DOE 1989 — Station 40 Station 40 Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

1989 DOE 1990 — Station 40 Station 40 Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

1990 DOE 1991 — Station 40 Station 40 Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

1991 DOE 1992a, DOE 

1992b

— Station 40 Station 40 Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

19925 DOE 1993a, DOE 

1993b

— — — Station 40 Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

Y-12 Stations:

1 –12

— —

1993 DOE 1994 — — — PAM 

Composite3

— — — — Y-12 Stations:

1 –12

1994 DOE 1995 — — — Station 40 — — — — Y-12 Stations:

1 –12

1995 DOE 1996 — Station 40 Station 40 Station 40 — — — — Y-12 Stations:

4, 5, and 8

1996 DOE 1997 — Station 40 Station 40 Station 40 — — — — Y-12 Stations:

4, 5, and 8

1997 DOE 1998 — Station 40 Station 40 Station 40 — — — — Y-12 Stations:

4, 5, and 8

1998 DOE 1999 — Station 40 Station 40 Station 40 — — — — Y-12 Stations:

4, 5, and 8

1999 DOE 2000 — — — Station 40 — — — — Y-12 Stations:

4, 5, and 8

20006 DOE 2001 — — — Station 40 Y-12 Stations: 

4, 5, and 8

Y-12 Stations: 

4, 5, and 8

— — —

20016 DOE 2002 — — — Station 40 Y-12 Stations: 

4, 5, and 8

Y-12 Stations: 

4, 5, and 8

— — —

NOTES

1. Station HP-12 was the initial designation for the ORNL Perimeter Air Monitoring (PAM) Station at the Midway Gate, located northeast of Y-12. After 1961, HP-12 was 

renumbered HP-32. After 1984, HP-12 was relocated closer to Y-12 and was re-designated as Station 40. Y-12 Stations 1 - 12 (initially designated A61-A72) are located in and 

around Y-12 .

2. Isotopes measured were 234U, 235U, 236U and 238U.

3. Ambient air concentrations only reported as an average for ALL stations within the PAM network.

4. Units used for uranium data presented in Volume 1 of the 1987 report (DOE 1988a) are incompatible with similar data presented in Volume 2 for the same year (DOE 1988b). 

Error is most likely due to units used in Volume 1 as units used in Volume 2 are consistent with preceding and proceeding years.

5. Incompatibility of data values between annual average uranium concentrations presented in Volume 1 of 1992 Annual Site Environmental Report (DOE 1993a) and quarterly data 

presented in Volume 2 of same year (DOE 1993b). No Errata were found for this year. Therefore, the averages presented in Volume 1 were used. Station 10 data were missing 

for U-235 from volume 1. Average is calculated from quarterly data presented in Volume 2.

6. Responsibility for Y-12 stations 4, 5 and 8 was transferred to the Tennessee Department of Environment and Conservation (TDEC). Samples collected were analyzed for gross α

and gross β only. Uranium analysis is only performed if gross measurements are elevated.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 13 of 50

There were three networks of monitoring stations initially established by ORNL:

1. A system of ten stations was located within the perimeter of ORNL: Local Air Monitoring 

(LAM) network. 

2. Seven stations were initially established around the ORR known as the Perimeter Air 

Monitoring (PAM) network. The number of stations within the PAM was later increased to 

nine. 

3. A third system of eight stations was established at distances of 12 to 120 miles from ORNL; 

this system was known as the Remote Air Monitoring (RAM) network.

Prior to 1983, the closest air monitoring station to Y-12 was the Midway Gate station which was part 

of the ORNL PAM network. This health physics station, initially designated as HP-12 (later renamed 

HP-32), was located north of the intersection of Bear Creek Road and Lafayette Drive (Figure 

4.1.2-1). A second station (HP-11) was located on Bethel Valley Road (Kerr Hollow). This station is 

far removed from the Y-12 facility and it is unlikely to provide relevant data. These stations are the 

only known locations for ambient air monitoring data in the vicinity of the Y-12 facility prior to 1983. 

Figure 4.1.2-1. Locations of ORNL Perimeter Air Monitoring (PAM) Stations. Station HP12 at Midway Gate (later renamed HP-32) is the closest station to the Y-12 facility prior to 

1983 (Abee 1961).

Samples were collected at HP-12/HP-32 by passing air continuously through a filter paper which 

would only accumulate particles considered to be respirable. Sample collection frequency varied 

during this period. However, most of the samples were collected weekly. Estimated concentrations 

were compared to maximum permissible concentrations to determine if further analyses were 

warranted.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 14 of 50

Earlier available data for this station (HP-12/HP-32) were characterized as “Activity” or as “Long-lived 

Activity.” No further characterization was available in the published reports. Gross β data was first 

available in 1963 and gross α results were first reported in 1965 (Table 4.1.2-1).

1971–1983: Environmental Monitoring Reports

This series of reports covers all the ORR facilities and the stations initially established by ORNL. A 

number of new stations established north of Y-12, were used to measure fluorides, sulfur and dustfall. Station HP-32 (previously designated HP-12) at the Midway Gate continued to be the only health 

physics monitoring station closest to Y-12. Data collected and presented in these reports for HP-32 

(Midway Gate) was limited to gross α and gross β as shown in Table 4.1.2-1 and a detailed analysis 

was performed only if the concentrations were above established maximum permissible 

concentrations. 

Uranium activity in air was reported beginning in 1975. However, the reported concentration was 

based on a composite sample taken from all stations with the PAM network. In 1975, high 

concentrations of ambient uranium were noted and were attributed to enrichment and processing 

activities at the Oak Ridge Gaseous Diffusion Plant (ORGDP) and Y-12. The elevated 

concentrations also noted in 1976 were attributed to operational problems with the pollution control on 

the purge cascade at ORGDP. Since these values were averaged for all PAM stations, no direct 

relationship to the operations at Y-12 could be made from these data sets. It is likely that data 

specific to Station HP-32 were collected. However, these data were not reported in any of the reports 

reviewed. 

Two changes in the air monitoring network were noted in 1983:

1. A second monitoring station was established east of Y-12. This station initially designated HP40 (later re-designated Station 40) was located along Bear Creek road at the northeast corner 

of the perimeter of the Y-12 facility (Figure 4.1.2-2). Samples collected at this station were 

analyzed for gross α and gross β activity and iodine-131 (131I), along with other radionuclides 

including fission products (FP), uranium and transuranics (TRU). These concentrations were 

averaged for all stations in the PAM network.

2. The second major change was the establishment of the eleven air monitoring stations in and 

around the perimeter of Y-12. These stations were established primarily to measure uranium. 

The location and operation of these stations is further described in the next section.

1984–1999: Annual Monitoring Report / Annual Site Environmental Report

After 1984, the amount of environmental monitoring increased substantially and this period is the most 

significant for uranium air monitoring at Y-12. The air monitors established in and around the Y-12 

perimeter, which began operations in 1983, were primarily for the measurement of uranium. 

Sampling for radioactive particulates was conducted by passing air continuously through filter papers. 

These filters were evaluated weekly for gross α and gross β activity. The filters were composited 

quarterly and were evaluated for four uranium isotopes (234U, 235U, 236U and 238U). Reports from 1988 

onward indicate that the filters were analyzed using alpha spectroscopy. No information on the 

analytical techniques employed before 1988 was immediately available. The Y-12 perimeter stations 

were increased to 12 stations beginning in 1985. The location of these stations is shown in Figure 

4.1.2-3.

Note that for 1985 and 1986, these stations were initially designated as A61 through A71. A twelfth 

station (Station 12, formerly A72) was added in 1985; however, this station was initially used to 

measure suspended particulates. Ambient uranium measurements at this station did not commence 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 15 of 50

Figure 4.1.2-2. Location of Station 40 incorporated into the ORNL Perimeter Air Monitoring 

(PAM) network in 1983. Station is located at the northeast perimeter of the Y-12 facility (DOE 

2002).

until 1987. With the establishment of the twelfth station, these stations were re-designated as Y-12 

Stations 1 through 12. Ambient uranium data for the twelve Y-12 stations included gross α and gross 

β and activity concentrations (μCi cm-3) for four uranium isotopes (234U, 235U, 236U and 238U). 

In 1993, the analysis program for radionuclides was revised to obtain total uranium (μg m-3) 

concentrations and the percentage of 235U. This approach was implemented to better correlate air 

concentrations with the stack emission data that were measured in terms of uranium mass. As shown 

in Table 4.1.2-2, data subsequent to, and including 1993, are reported in terms of μg m-3. 

Since there were no Federal or State regulations, or DOE Orders that required the monitoring of 

uranium releases, and with the reduction of plant operations, the usefulness of the Y-12 stations was 

re-evaluated in 1993. With the installation of an ambient air monitoring station at the Scarboro 

community (located north of Y-12), the Y-12 stations were considered redundant. In addition, 

processes that resulted in the emission of enriched and depleted uranium were equipped with stack 

samplers that were reviewed and approved by the Environmental Protection Agency (EPA) to meet 

the requirements of the National Emission Standards for Hazardous Air Pollutants (NESHAPs) 

regulations. Therefore, sampling at all but three of the stations (4, 5, and 8) was discontinued after 

1994. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 16 of 50

Figure 4.1.2-3. Locations of the twelve Y-12 perimeter air monitoring stations (DOE 1990)

Table 4.1.2-2. Availability of uranium air concentration data measured at the twelve Y-12 air 

monitoring stations. 

Year

Reported 

uranium data Units

Y-12 monitoring station

1 2 3 4 5 6 7 8 9 10 11 12

1983 Total Activity μCi mL-1           

1984 Total Activity μCi mL-1           

1985 Isotopic1

μCi cm-3           

1986 Isotopic1

μCi cm-3           

19872 Isotopic1

μCi cm-3            

1988 Isotopic1

μCi cm-3            

1989 Isotopic1

μCi cm-3            

1990 Isotopic1

μCi cm-3            

1991 Isotopic1

μCi cm-3            

1992 Isotopic1

μCi cm-3            

1993 Total Mass μg m-3            

19943 Total Mass μg m-3           

19954 Total Mass μg m-3   

1996 Total Mass μg m-3   

1997 Total Mass μg m-3   

1998 Total Mass μg m-3   

1999 Total Mass μg m-3   

1. Concentrations reported for 234U, 235U, 236U and 238U.

2. Error in reporting units found for 1987 data. See explanation presented with Table 4.1.2-1.

3. Station 1 inoperable for 1994 and discontinued in 1995.

4. Sampling at all but three stations discontinued.

2001–2002: Tennessee Department of Environment and Conservation

With an agreement reached with the Tennessee Department of Environment and Conservation 

(TDEC), TDEC personnel took over responsibility for sampling and analysis of the remaining three 

uranium air sampling stations. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 17 of 50

Samples collected from the three remaining Y-12 Stations (4, 5 and 8) by TDEC are only analyzed for 

gross α and gross β. Gamma spectrometry was performed only on samples that exhibited elevated 

gross results. Consequently, uranium air concentrations were no longer available after 1999. 

4.3 APPROACH FOR ESTIMATING ON SITE AIR CONCENTRATIONS

4.3.1

Prior to 1983, the various networks of air monitoring stations in and around the ORR were established 

to monitor for the FP releases. These stations did not measure on site concentrations at Y-12. From 

1959 through 1982, the ambient air monitoring station closest to Y-12 was health physics station HP32 (formerly HP-12), located approximately 0.25 miles from Y-12. In 1983, the first stations dedicated 

to measuring ambient air concentrations at Y-12 were established. 

Usability of Air Monitoring Data

Ambient air monitoring at Y-12 prior to 1983 is insufficient for estimating environmental doses for 

several reasons:

• Concentrations of airborne uranium within the Y-12 perimeter were measured from 1983 

through 1999. This seventeen-year period represents less than 30% of the operational history 

of the site. In addition, these data were not collected during the time operations and releases 

were at their maximum. Therefore these data cannot be used as estimators of historic air 

concentrations. 

• Prior to 1983, the closest health physics station to Y-12 was PAM Station HP-32 (formerly 

known as HP-12). This station was located at Midway Gate, which is north of the intersection 

of Bear Creek Road and Lafayette Drive (approximately 0.25 miles from Y-12). Station 40, 

which replaced station HP-32, began operating in 1983. However, this station is also not 

located on site. 

• Data from these off site stations consisted of total activity, FP activity, gross α and/or gross β. 

Uranium concentrations were reported as averages across all stations within the PAM 

network. 

• No environmental data of any use to this assessment were found for years preceding 1959. 

The only reported on site ambient air concentrations prior to 1959 were for gross α and/or 

gross β. 

• An assessment of the measured gross α air concentrations at the health physics stations 

(HP32 and Station 40) show limited correlation to the uranium release quantities estimated for 

the period. 

Given the distance between the main production areas of Y-12 and the locations of these stations 

(HP-32 and Station 40), it is unlikely that these stations reflect the level of on site ambient uranium. 

Consequently, these stations do not present a representative measure of air concentrations at Y-12 

and cannot be used to estimate on site doses. 

The release of contaminants into the atmosphere at Y-12 occurred primarily as a result of plant 

fabrication operations. There are reportedly over 700 permitted air pollution sources that are tied into 

the exhaust ventilation systems of Y-12 (DOE 1989). As reported in the 1988 ASER (DOE 1989), 

approximately 85 exhausts serve areas where depleted uranium (DU) or enriched uranium (EU) were 

processed. As discussed in the Oak Ridge Dose Reconstruction (ORDR) Report (ChemRisk 1999), 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 18 of 50

the monitoring of uranium emissions from the various buildings has changed significantly over time. 

Some of these release points were through monitored stacks; others were through vents and exhaust 

systems. 

Estimating airborne concentrations at locations around Y-12 using traditional dispersion and transport 

modeling approaches is confounded by a number of factors:

• Numerous release points which include stacks, vents, and other emission sources,

• The characteristics of the release points,

• The relatively short distances between the release points and the on site receptor locations,

• The complexity of the topography of Y-12, including the presence of Pine Ridge to the north, 

and,

• The density and configuration of buildings at Y-12.

These factors contribute to the complexity of attempting to model the releases using traditional 

atmospheric dispersion modeling methods. In addition, the approximations necessary to overcome 

these complexities would increase the level of uncertainty in the estimate of doses. 

4.3.2

Due to the limitations of the available data and the complexity of modeling releases as discussed 

above, an alternative approach was developed for estimating airborne uranium concentrations. An 

empirical relationship was developed using on site measured air concentrations and estimated 

uranium release estimates. This approach circumvents the need for air dispersion modeling by 

providing a direct relationship between uranium air concentrations and uranium releases. In addition, 

this approach can be used to estimate air concentrations prior to 1983 by using the empirical Chi/Q 

value and the estimated uranium releases for earlier years.

Empirical Chi/Q (χ/Q) Approach for Estimating Air Concentrations

Using the available uranium data for 1983 through 1999, the annual average uranium air 

concentration measured at the Y-12 air monitoring stations is divided by the corresponding estimates 

for a given year to estimate an annual, station specific, Chi/Q value. The empirical relationship is 

described by Equation 4.2.2-1 (ChemRisk 1999). 

Re )(

)( )(

3

3

UraniumMass lease kg

Uranium Air Concentration mkg Chi mQ

− − = (4.2.2-1) 

As discussed in the previous section, there were twelve Y-12 air monitoring stations that operated 

from 1984 through 1999. Of these 12 stations, four are located within the Y-12 perimeter; the 

remaining 8 stations are located beyond the fence-line of the facility. These on site locations are Y-12 

air monitoring stations 2, 4, 8 and 12. These stations are located within the boundary of the facility 

and provide coverage of the west (station 8), southeast (station 12), northeast (station 2) and the 

center (station 4) portions of the facility. Annual Chi/Q values were estimated for these four locations. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 19 of 50

4.3.3

As shown in Table 4.1.2-2, the Y-12 monitoring stations began operations in 1983; however, the type 

of data reported varied during the 17 years of available information. Uranium air concentrations were 

reported as either total uranium activity, uranium isotope activity or by total uranium mass. Important 

factors associated with the available information include:

Air Concentrations by Location (Chi)

• Total uranium activity only was reported for 1983 and 1984. To convert the data for these 

years to isotopic concentrations, the isotopic ratio of the 1985 data for the four uranium 

isotopes (234U, 235U, 236U, and 238U) was used to partition the measured total uranium activity. 

This was necessary in order to calculate a mass-based air concentration that is consistent with 

the other years.

• After 1992, all data were reported in terms of uranium mass (μg m-3). Therefore, data from all 

previous years was converted to a mass basis for consistency. Conversions were achieved 

using specific activities for all four isotopes.

• All stations with the exception of stations 4, 5 and 8 were decommissioned after the 1994 

monitoring period.

• Station 1 was inoperable in 1994, and Station 12 began operations in 1987, four years after 

the other eleven stations were brought on line. 

• After 1999, responsibility for the remaining stations (4, 5 and 8) was transferred to TDEC and 

only assessments of gross α and gross β were made from the samples collected. 

All measured air concentrations were converted to kg m-3 of total uranium so that data dimensions are 

consistent for all years. Annual average measured air concentrations for the four Y-12 stations 

selected are tabulated in Tables 4.2.3-1 through 4.2.3-4. Annual average values for gross α, gross β, 234U, 235U, 236U and 238U are included. All reported concentrations for the uranium isotopes are 

converted to a mass basis (kg m-3) based on specific activities for the four uranium isotopes. For 

1983 and 1984, only the total uranium activity was reported (μCi cm-3). The reported activity was 

apportioned to the four uranium isotopes based on the isotopic activity reported for 1985. This 

assumed that the uranium enrichments for 1983 and 1984 were similar to those reported for 1985. 

4.3.4

Release estimates for all buildings at Y-12 were previously estimated by Task 6 of the ORDR Project 

(ChemRisk 1999). These independent estimates were based on a reconstruction of releases from 

stack monitoring data. Estimates of uranium releases were reconstructed for individual exhaust 

stacks and vents and were based on information available for individual buildings, uranium processes 

and from indoor air monitoring data.

Release Estimates (Q)

The reconstructed estimates cover the period from 1944 through 1988. Estimates from 1989 through 

1995 were based on reported releases estimated by DOE. For the purposes of this study, release 

estimates after 1995 were derived from the ASERs. 

A compilation of these release estimates is presented in Table 4.2.4-1. A combined 234/235U release 

estimate was reconstructed as part of the ORDR Project (ChemRisk 1999). This approach was 

selected by the Dose Reconstruction Team to generate a conservative estimate of off site dose. 

Since these release estimates cannot be distinguished without further reconstruction, the air 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

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Table 4.2.3-1. Annual average air concentrations and estimated Chi/Q values for Y-12 Station 2. 

Year

Gross α 

(μCi cm-3) 

Gross β 

(μCi cm-3) 

234U 

(μCi cm-3)

235U 

(μCi cm-3)

236U 

(μCi cm-3)

238U 

(μCi cm-3)

Total uranium

(mass or activity)

Conversion to 

mass3

(kg m-3)

Y-12 release

estimates

(kg)

CHI/Q

(m-3)

19831 - - 3.90E-15 1.61E-16 1.78E-16 2.80E-16 4.52E-15 (μCi cm-3

) 9.08E-13 208 4.37E-15

19841 - - 7.08E-15 2.92E-16 3.23E-16 5.08E-16 8.20E-15 (μCi cm-3

) 1.65E-12 331 4.98E-15

1985 8.20E-15 2.00E-14 4.60E-15 1.90E-16 2.10E-16 3.30E-16 - 1.07E-12 211 5.08E-15

1986 6.00E-15 2.80E-14 3.80E-15 1.30E-16 1.00E-16 3.20E-16 - 1.01E-12 213 4.75E-15

1987 3.32E-15 1.65E-14 1.30E-15 5.00E-17 8.20E-17 1.30E-16 - 4.10E-13 153 2.68E-15

1988 3.71E-15 2.09E-14 1.55E-15 6.90E-17 8.90E-17 1.81E-16 - 5.71E-13 145 3.94E-15

1989 2.70E-15 1.90E-14 1.28E-15 7.00E-17 2.60E-17 1.01E-16 - 3.33E-13 44 7.56E-15

1990 1.31E-15 1.03E-14 4.00E-16 2.49E-17 2.25E-17 5.73E-17 - 1.82E-13 21 8.67E-15

1991 5.68E-16 6.88E-15 2.00E-16 4.20E-18 2.90E-18 2.14E-17 - 6.55E-14 21 3.12E-15

1992 1.26E-16 4.52E-15 6.14E-17 4.00E-18 2.40E-18 1.05E-17 - 3.31E-14 7 4.72E-15

19932 - - - - - - 6.00E-05 (μg m-3

) 6.00E-14 3 2.00E-14

19942 - - - - - - 5.00E-05 (μg m-3

) 5.00E-14 24 2.08E-15

19952 - - - - - - - - - - 

19962 - - - - - - - - - -

19972 - - - - - - - - - - 

19982 - - - - - - - - - -

19992 - - - - - - - - - -

Station 2 Chi/Q (m-3)

Minimum 2.08E-15

Maximum 2.00E-14

Count 12

Geometric Mean (GM) 4.96E-15

Geometric Standard Deviation (GSD) 1.81

50th Percentile (Lognormal) 4.96E-15

95th Percentile (Lognormal) 1.31E-14

NOTE

1 1983 and 1984 data were reported as total uranium activity only. 234U, 235U, 236U and 238U air concentrations were calculated based on isotopic activity ratios from 1985 data. 

2 Reported annual average concentration in μg m-3. 

3 Conversion to mass using specific activities for 234U, 235U, 236U and 238U.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

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Table 4.2.3-2. Annual average air concentrations and estimated Chi/Q values for Y-12 Station 4. 

Year

Gross α 

(μCi cm-3) 

Gross β 

(μCi cm-3) 

234U 

(μCi cm-3)

235U 

(μCi cm-3)

236U 

(μCi cm-3)

238U 

(μCi cm-3)

Total uranium

(mass or activity)

Conversion to 

mass3

(Kg m-3)

Y-12 Release

estimates

(kg)

CHI/Q

(m-3)

19831 - - 9.61E-15 4.40E-16 2.73E-16 3.69E-16 1.07E-14 (μCi cm-3

) 1.30E-12 208 6.27E-15

19841 - - 1.89E-14 8.64E-16 5.36E-16 7.25E-16 2.10E-14 (μCi cm-3

) 2.56E-12 331 7.74E-15

1985 2.60E-14 3.20E-14 1.90E-14 8.70E-16 5.40E-16 7.30E-16 - 2.58E-12 211 1.22E-14

1986 2.27E-14 5.12E-14 1.57E-14 6.70E-16 7.00E-16 9.60E-16 - 3.17E-12 213 1.49E-14

1987 7.25E-15 1.97E-14 4.10E-15 1.80E-16 2.10E-16 3.40E-16 - 1.10E-12 153 7.17E-15

1988 5.69E-15 2.25E-14 4.39E-15 1.00E-16 1.15E-16 3.31E-16 - 1.03E-12 145 7.11E-15

1989 3.67E-15 2.08E-14 2.40E-15 6.90E-17 4.00E-17 2.69E-16 - 8.31E-13 44 1.89E-14

1990 1.88E-15 1.10E-14 1.47E-15 4.83E-17 4.61E-17 8.35E-17 - 2.71E-13 21 1.29E-14

1991 6.73E-16 5.64E-15 5.82E-16 1.55E-17 9.00E-18 2.89E-17 - 9.32E-14 21 4.44E-15

1992 5.21E-16 4.10E-15 2.23E-16 1.04E-17 3.70E-18 4.69E-17 - 1.44E-13 7 2.06E-14

19932 - - - - - - 1.51E-03 (μg m-3

) 1.51E-12 3 5.03E-13

19942 - - - - - - 1.20E-04 (μg m-3

) 1.20E-13 24 5.00E-15

19952 - - - - - - 8.00E-05 (μg m-3

) 8.00E-14 2 4.00E-14

19962 - - - - - - 9.00E-05 (μg m-3

) 9.00E-14 10 9.00E-15

19972 - - - - - - 1.50E-04 (μg m-3

) 1.50E-13 6 2.50E-14

19982 - - - - - - 1.10E-04 (μg m-3

) 1.10E-13 10 1.10E-14

19992 - - - - - - 8.00E-05 (μg m-3

) 8.00E-14 4 2.00E-14

Station 4 Chi/Q (m-3)

Minimum 4.44E-15

Maximum 5.03E-13

Count 17

Geometric Mean (GM) 1.44E-14

Geometric Standard Deviation (GSD) 3.00

50th Percentile (Lognormal) 1.44E-14

95th Percentile (Lognormal) 8.73E-14

NOTE

1 1983 and 1984 data were reported as total uranium activity only. 234U, 235U, 236U and 238U air concentrations were calculated based on isotopic activity ratios from 1985 data. 

2 Reported annual average concentration in μg m-3. 

3 Conversion to mass using specific activities for 234U, 235U, 236U and 238U.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

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Table 4.2.3-3. Annual average air concentrations and estimated Chi/Q values for Y-12 Station 8. 

Year

Gross α 

(μCi cm-3) 

Gross β 

(μCi cm-3) 

234U 

(μCi cm-3)

235U 

(μCi cm-3)

236U 

(μCi cm-3)

238U 

(μCi cm-3)

Total uranium

(mass or activity)

Conversion to 

mass3

(kg m-3)

Y-12 release

estimates

(kg)

CHI/Q

(m-3)

19831 - - 7.20E-15 3.06E-16 2.27E-16 8.19E-16 8.55E-15 (μCi cm-3

) 2.58E-12 208 1.24E-14

19841 - - 6.65E-15 2.82E-16 2.10E-16 7.56E-16 7.90E-15 (μCi cm-3

) 2.38E-12 331 7.19E-15

1985 1.30E-14 2.20E-14 7.30E-15 3.10E-16 2.30E-16 8.30E-16 - 2.61E-12 211 1.24E-14

1986 1.22E-14 3.10E-14 7.20E-15 3.10E-16 1.70E-16 7.50E-16 - 2.37E-12 213 1.11E-14

1987 8.30E-15 1.90E-14 6.30E-15 2.90E-16 2.00E-16 3.70E-16 - 1.24E-12 153 8.08E-15

1988 4.99E-15 2.46E-14 2.21E-15 1.37E-16 1.68E-16 3.87E-16 - 1.21E-12 145 8.38E-15

1989 4.14E-15 2.16E-14 1.68E-15 1.37E-16 6.70E-17 3.23E-16 - 1.02E-12 44 2.33E-14

1990 1.69E-15 1.18E-14 4.06E-16 1.99E-17 7.90E-18 1.04E-16 - 3.18E-13 21 1.51E-14

1991 5.46E-16 6.51E-15 3.20E-16 5.19E-17 3.60E-18 6.81E-17 - 2.26E-13 21 1.08E-14

1992 1.88E-16 4.55E-15 1.90E-16 2.44E-17 5.10E-18 2.46E-17 - 8.44E-14 7 1.21E-14

19932 - - - - - - 3.90E-04 (μg m-3

) 3.90E-13 3 1.30E-13

19942 - - - - - - 8.00E-05 (μg m-3

) 8.00E-14 24 3.33E-15

19952 - - - - - - 2.00E-04 (μg m-3

) 2.00E-13 2 1.00E-13

19962 - - - - - - 9.00E-05 (μg m-3

) 9.00E-14 10 9.00E-15

19972 - - - - - - 9.05E-05 (μg m-3

) 9.05E-14 6 1.51E-14

19982 - - - - - - 1.10E-05 (μg m-3

) 1.10E-14 10 1.10E-15

19992 - - - - - - 8.00E-05 (μg m-3

) 8.00E-14 4 2.00E-14

Station 8 Chi/Q (m-3)

Minimum 1.10E-15

Maximum 1.30E-13

Count 17

Geometric Mean (GM) 1.26E-14

Geometric Standard Deviation (GSD) 2.97

50th Percentile (Lognormal) 1.26E-14

95th Percentile (Lognormal) 7.53E-14

NOTE

1 1983 and 1984 data were reported as total uranium activity only. 234U, 235U, 236U and 238U air concentrations were calculated based on isotopic activity ratios from 1985 data. 

2 Reported annual average concentration in μg m-3. 

3 Conversion to mass using specific activities for 234U, 235U, 236U and 238U.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 

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Table 4.2.3-4. Annual average air concentrations and estimated Chi/Q values for Y-12 Station 12. 

Year

Gross α 

(μCi cm-3) 

Gross β 

(μCi cm-3) 

234U 

(μCi cm-3)

235U 

(μCi cm-3)

236U 

(μCi cm-3)

238U 

(μCi cm-3)

Total uranium

(mass or activity)

Conversion to 

mass3

(kg m-3)

Y-12 release

estimates

(kg)

CHI/Q

(m-3)

19831 - - - - - - - - - -

19841 - - - - - - - - - -

19851 - - - - - - - - - -

19861 - - - - - - - - - -

1987 2.78E-15 1.21E-14 5.20E-16 6.10E-17 7.00E-17 5.70E-17 - 1.99E-13 153 1.30E-15

1988 4.06E-15 2.31E-14 1.01E-15 7.40E-17 7.20E-17 1.27E-16 - 4.12E-13 145 2.84E-15

1989 3.10E-15 2.08E-14 1.32E-15 8.80E-17 6.90E-17 1.15E-16 - 3.83E-13 44 8.71E-15

1990 1.61E-15 1.23E-14 3.21E-16 1.48E-17 8.90E-18 5.35E-17 - 1.66E-13 21 7.90E-15

1991 4.93E-16 6.84E-15 1.34E-16 3.46E-17 9.30E-18 2.79E-17 - 9.90E-14 21 4.71E-15

1992 2.14E-16 5.41E-15 5.62E-17 2.50E-18 1.50E-18 8.10E-18 - 2.52E-14 7 3.60E-15

19932 - - - - - - 6.00E-05 (μg m-3

) 6.00E-14 3 2.00E-14

19942 - - - - - - 5.00E-05 (μg m-3

) 5.00E-14 24 2.08E-15

19952 - - - - - - - - - -

19962 - - - - - - - - - -

19972 - - - - - - - - - -

19982 - - - - - - - - - -

19992 - - - - - - - - - -

Station 12 Chi/Q (m-3)

Minimum 1.30E-15

Maximum 2.00E-14

Count 8

Geometric Mean (GM) 4.54E-15

Geometric Standard Deviation (GSD) 2.40

50th Percentile (Lognormal) 4.54E-15

95th Percentile (Lognormal) 1.92E-14

NOTE

1 Station was not operational and was brought on line in 1987

2 Reported annual average concentration in μg m-3. 

3 Conversion to mass using specific activities for 234U, 235U, 236U and 238U.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 24 of 50

1944–1988

Release estimates were independently reconstructed 

as part of the ORDR Project. Estimates were made 

of total uranium releases (kg and Ci) and isotopic 

releases (

234/235U and 238U).

(ChemRisk 1999). Table 

D-1 of Appendix D of the 

Task 6 Report (Volume 5)

1989–1995

Release estimates reported in the ORDR were not 

independently reconstructed. Values were based on 

estimates reported by DOE.

(ChemRisk 1999). Table 

D-1 of Appendix D of the 

Task 6 Report (Volume 5)

1996–2001 Independent sources were not available. Estimates 

are those reported in the ORR-ASER for Y-12.

(DOE 2000, DOE 2001, 

DOE 2002)

concentrations used in this assessment are in terms of a combined activity (234/235U). Figure 4.2.4-1 

shows the distribution of 234/235U and 238U with time. The highest reconstructed 234/235U release was in 

1958 (17.4 Ci); the highest 238U release was in 1959 (2.0 Ci). 

0.001

0.01

0.1

1

10

100

1944 1954 1964 1974 1984 1994

Y-12 Uranium Release Estimates (Ci)

Year

Uranium-234/ 235 Uranium-238

Figure 4.2.4-1. Distribution of release estimates for the Y-12 facility. Release estimates for 

1944 through 1995 were independently reconstructed by the Oak Ridge Dose Reconstruction 

Project (ChemRisk 1999).

4.3.5

To validate the Chi/Q approach, the uranium air concentrations measured at each of the four Y-12 

stations of interest (2, 4, 8 and 12) were plotted against the reported uranium release estimates to 

determine if a valid correlation exists. A correlation coefficient (R2

) was estimated from the plotted 

data. Figures 4.2.5-1 through 4.2.5-4 show the relationship of measured air concentrations with 

uranium release estimates. Values of the correlation coefficient (R2

) are included.

Correlation of Air Concentrations with Releases
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 25 of 50

R2 = 0.95

0.0E+00

2.0E-13

4.0E-13

6.0E-13

8.0E-13

1.0E-12

1.2E-12

1.4E-12

1.6E-12

1.8E-12

0 50 100 150 200 250 300 350

Total Uranium Air Concentration measured at 

Station 2 (kg m-3)

Uranium Release Estimates (kg)

Figure 4.2.5-1. Plot of annual total uranium air concentration measured at Station 2 

versus estimated uranium releases. Correlation coefficient R2 = 0.95.

R2 = 0.70

0.0E+00

5.0E-13

1.0E-12

1.5E-12

2.0E-12

2.5E-12

3.0E-12

3.5E-12

0 50 100 150 200 250 300 350

Total Uranium Air Concentration Measured at 

Station 4 (kg m-3)

Uranium Releases Estimates (kg)

Figure 4.2.5-2. Plot of annual total uranium air concentration measured at Station 4 

versus estimated uranium releases. Correlation coefficient R2 = 0.70.
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 26 of 50

R2 = 0.87

0.0E+00

5.0E-13

1.0E-12

1.5E-12

2.0E-12

2.5E-12

3.0E-12

3.5E-12

0 50 100 150 200 250 300 350

Uranium Release Estimates (kg)

Total Uranium Air Concentration Measured at 

Station 8 (kg m -3)

Figure 4.2.5-3. Plot of annual total uranium air concentration measured at Station 8 

versus estimated uranium releases. Correlation coefficient R2 = 0.87.

R2

 = 0.19

0.0E+00

5.0E-14

1.0E-13

1.5E-13

2.0E-13

2.5E-13

3.0E-13

3.5E-13

4.0E-13

4.5E-13

0 20 40 60 80 100 120 140 160

Uranium Release Estimates (kg)

Total Uranium Air Concentration Measured at 

Station 12 (kg m -3)

Figure 4.2.5-4. Plot of annual total uranium air concentration measured at Station 12 

versus estimated uranium releases. Correlation coefficient R2 = 0.19.

The R2 values show an acceptable correlation between the measured air concentrations and the 

release estimates indicating that the empirical Chi/Q approach is valid. The only exception is station 

12. The poor correlation is most likely due to the fact that there are only 8 data points for this station. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 27 of 50

This station did not start collecting samples until 1987, which is four years after the other stations 

were brought online. In addition, the range of uranium release estimates for the years when this 

station was operational, is significantly lower than for previous years. 

Generally, the correlation of uranium air concentrations with uranium releases displays a strong 

relationship indicating that the stations appropriately represent an adequate measure of ambient 

uranium concentrations as result of uranium releases from Y-12 operations.

4.3.6

The empirical Chi/Q relationship, described in Equation 4.2.2-1 above, uses the average uranium air 

concentration at each station (Chi) from Tables 4.2.3-1 to 4.2.3-4, and the release estimates (Q) in 

Table 4.2.4-1. Values of Chi/Q are calculated for each of the four locations (Stations 2, 4, 8 and 12) 

by dividing the average annual air concentration estimated in kg m-3 by the release estimates for that 

year in kg. Annual Chi/Q values were calculated for each station for each year for which air 

concentrations were available. 

Estimating Chi/Q for Y-12 Stations

Station 2 Air concentrations were reported for 1983 through 1994. This 

station was decommissioned after the 1994 sampling rounds. 12 Chi/Q values

Station 4 Air concentrations were reported for 1983 through 1999. 17 Chi/Q values 

per station. Station 8 Responsibility for this station was transferred to TDEC. Only 

gross α and gross β measurements after 1999. 

Station 12

Air concentrations were reported for 1987 through 1994. This 

station was added to the network in 1987, and was 

decommissioned after the 1994 sampling rounds. 

8 Chi/Q values

Table 4.2.4-1. Compiled annual uranium release estimates (Q).

Year

Uranium

(kg)

Uranium

(Ci)

234/235U 

(kg)

238U 

(kg)

234/235U 

(Ci)

238U 

(Ci) Source

1944 311 0.35 5 307 0.24 0.11 ChemRisk 1999 (Table D-1)

1945 665 0.63 8 657 0.41 0.22 ChemRisk 1999 (Table D-1)

1946 385 0.44 6 379 0.31 0.13 ChemRisk 1999 (Table D-1)

1947 250 0.34 5 245 0.26 0.08 ChemRisk 1999 (Table D-1)

1948 650 0.39 3 647 0.17 0.22 ChemRisk 1999 (Table D-1)

1949 650 0.39 3 647 0.17 0.22 ChemRisk 1999 (Table D-1)

1950 650 0.39 3 647 0.17 0.22 ChemRisk 1999 (Table D-1)

1951 650 0.39 3 647 0.17 0.22 ChemRisk 1999 (Table D-1)

1952 650 0.39 3 647 0.17 0.22 ChemRisk 1999 (Table D-1)

1953 4015 2.04 12 4002 0.67 1.36 ChemRisk 1999 (Table D-1)

1954 3765 1.86 11 3754 0.58 1.28 ChemRisk 1999 (Table D-1)

1955 3765 1.87 11 3754 0.59 1.28 ChemRisk 1999 (Table D-1)

1956 3037 4.2 41 2995 3.2 1 ChemRisk 1999 (Table D-1)

1957 2309 6.6 72 2236 5.8 0.8 ChemRisk 1999 (Table D-1)

1958 5657 19.2 214 5443 17.4 1.8 ChemRisk 1999 (Table D-1)

1959 6149 13.9 148 6001 11.9 2 ChemRisk 1999 (Table D-1)

1960 934 2.73 28 906 2.43 0.31 ChemRisk 1999 (Table D-1)

1961 1321 4.33 45 1276 3.9 0.43 ChemRisk 1999 (Table D-1)

1962 1390 4.67 49 1341 4.21 0.46 ChemRisk 1999 (Table D-1)

1963 2091 2.83 28 2063 2.1 0.7 ChemRisk 1999 (Table D-1)

1964 2672 1.58 10 2662 0.68 0.91 ChemRisk 1999 (Table D-1)

1965 635 3.61 42 593 3.41 0.2 ChemRisk 1999 (Table D-1)
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 28 of 50

Table 4.2.4-1 (Continued). Compiled annual uranium release estimates (Q).

Year

Uranium

(kg)

Uranium

(Ci)

234/235U

(kg)

238U

(kg)

234/235U

(Ci)

238U

(Ci) Source

1966 921 1.4 14 907 1.09 0.31 ChemRisk 1999 (Table D-1)

1967 339 0.62 6 332 0.5 0.11 ChemRisk 1999 (Table D-1)

1968 439 0.37 3 436 0.22 0.15 ChemRisk 1999 (Table D-1)

1969 247 1.05 12 235 0.97 0.08 ChemRisk 1999 (Table D-1)

1970 295 1.68 19 276 1.59 0.09 ChemRisk 1999 (Table D-1)

1971 575 2.26 25 549 2.07 0.19 ChemRisk 1999 (Table D-1)

1972 874 3.95 47 827 3.66 0.28 ChemRisk 1999 (Table D-1)

1973 410 3.36 39 371 3.23 0.13 ChemRisk 1999 (Table D-1)

1974 208 0.35 4 204 0.28 0.07 ChemRisk 1999 (Table D-1)

1975 210 0.59 7 203 0.52 0.07 ChemRisk 1999 (Table D-1)

1976 208 0.4 4 204 0.33 0.07 ChemRisk 1999 (Table D-1)

1977 206 0.23 2 204 0.16 0.07 ChemRisk 1999 (Table D-1)

1978 206 0.24 2 204 0.17 0.07 ChemRisk 1999 (Table D-1)

1979 207 0.31 3 204 0.24 0.07 ChemRisk 1999 (Table D-1)

1980 222 0.54 6 216 0.47 0.07 ChemRisk 1999 (Table D-1)

1981 207 0.36 4 203 0.29 0.07 ChemRisk 1999 (Table D-1)

1982 207 0.55 6 201 0.48 0.07 ChemRisk 1999 (Table D-1)

1983 208 0.48 5 203 0.41 0.07 ChemRisk 1999 (Table D-1)

1984 331 0.46 5 326 0.35 0.11 ChemRisk 1999 (Table D-1)

1985 211 0.35 4 207 0.28 0.07 ChemRisk 1999 (Table D-1)

1986 213 0.42 5 208 0.35 0.07 ChemRisk 1999 (Table D-1)

1987 153 0.64 7 146 0.59 0.05 ChemRisk 1999 (Table D-1)

1988 145 0.35 4 142 0.3 0.05 ChemRisk 1999 (Table D-1)

1989 44 0.15 7 37 0.15 0.014 ChemRisk 1999 (Table D-1)

1990 21 0.8 6 15 0.08 0.007 ChemRisk 1999 (Table D-1)

1991 21 0.05 1 20 0.04 0.01 ChemRisk 1999 (Table D-1)

1992 7 0.04 1 7 0.04 0.006 ChemRisk 1999 (Table D-1)

1993 3 0.03 0.4 3 0.03 0.003 ChemRisk 1999 (Table D-1)

1994 24 0.04 0.4 24 0.03 0.002 ChemRisk 1999 (Table D-1)

1995 2 0.02 0.3 2 0.02 0.0021 ChemRisk 1999 (Table D-1)

1996 9.7 - - - - - DOE 2000, page 6-2

1997 6 - - - - - DOE 2000, page 6-2

1998 10 - - - - - DOE 2000, page 6-2

1999 3.9 - - - - - DOE 2000, page 6-2

2000 2.2 - - - - - DOE 2001, page 6-5

2001 3.4 - - - - DOE 2002, page 6-5

Given the limited number of data points, a definitive characterization of the underlying distribution was 

not possible with any statistical certainty. However, the distribution of Chi/Q values exhibit 

characteristics of a lognormal distribution with a defined tail of higher values. Estimations of central 

tendency were made assuming the distribution of the Chi/Q values for each station was lognormal 

and estimates of the geometric mean (GM) and geometric standard deviation (GSD) are included in 

Tables 4.2.3-1 to 4.2.3-4. Estimates of the 50th and 95th percentile value of the Chi/Q value for each 

station were generated assuming the underlying distributions were lognormal. The percentiles were 

calculated using Equation 4.2.6-1, as described by Gilbert (1987).

ˆ exp( ) p += sZyx yp Equation 4.2.6-1 

where: 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 29 of 50

p xˆ = pth percentile of data set assuming distribution is lognormal,

y = arithmetic mean of the log transformed values of Chi/Q,

Zp = pth percentile of a standard normal distribution,

sy = standard deviation of the log transformed values of Chi/Q.

4.4 ESTIMATION OF AIR CONCENTRATIONS

Uranium air concentrations and annual intakes were calculated for the four on site locations at Y-12. 

These locations are represented by Y-12 air monitoring stations 2, 4, 8 and 12. These stations are 

located within the boundary of the facility and provide coverage of the west (station 8), southeast 

(station 12), northeast (station 2) and the center (station 4) portions of the facility (Figure 4.3-1).

Figure 4.3-1. Locations of Y-12 perimeter air monitoring stations (DOE 1990). 

Utilizing the Chi/Q estimates for each station, and the annual Y-12 airborne release estimates in Table 

4.2.4-1, annual uranium air concentrations (Ci m-3) at the four locations were obtained by multiplying 

the Chi/Q value for each station (m-3) by the uranium release estimate (Ci) for 234/235U and 238U. 

Annual uranium air concentration was calculated for each of the four specified locations for all years 

from 1944 to 2002. The air concentrations were estimated using the 50th and 95th percentile values 

for the Chi/Q values for each station. Even though measured uranium concentrations in air were 

available for 1983 through 1999, the air concentrations generated by the Chi/Q approach were used 

to estimate intakes. This approach was selected to maintain consistency with the preceding years. 

The ORDR Project estimated releases from 1944 to 1995. Thus, this source cannot be used to 

estimate air concentrations from 1996 to 2002. The release estimates in Table 4.2.4-1 show a 

definite downward trend for the years preceding 1995 (Figure 4.3-2). Thus, it is conservative to 

assume that the air concentrations reported from 1996 to 2002 are equal to the concentrations 

reported for 1995.

Air concentrations and intakes for the four on site locations are presented in Tables D-1 to D-4 in 

Attachment D. The uranium air concentrations are based on the 50th and 95th percentile value of the 

lognormally distributed Chi/Q. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 30 of 50

In addition, a site wide average air concentration and intake were estimated based on the annual 

concentrations from stations 2, 4, 8 and 12. These values are reported in Table D-5 in Attachment D. 

0.001

0.01

0.1

1

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

Year

Uranium Releases (Ci)

Uranium-234/235 Uranium-238

Figure 4.3-2. Distribution of 234/235U and 238U release estimates for the years 1985 

through 1995. The trend shows a definite downward trend for the years preceding 

1995. 

The maximum air concentrations for the uranium isotopes from all four locations were also compiled. 

The 50th and 95th percentiles of both air concentration and intake are presented in Table D-6 in 

Attachment D. Note that the percentiles are based on the statistics of the Chi/Q estimation and not on 

the data from the four stations. 

Estimates of intake assume 2,000 h y-1 exposure. An inhalation rate of 1.2 m3

 h-1 generates an 

annual intake off 2,400 m3

 y-1. 

For estimating air concentrations and intakes 

for the four specific on site locations at Y-12 by 

selecting the location that closely represents 

the exposure location.

Tables D-1 through D-4 

Average and

95th-percentile 

air concentration 

and intake for 234/235U and 238U 

For estimating Y-12 average air concentrations 

and intakes based on an annual average from 

all four on site locations. 

Table D-5 

Maximum air concentrations and intakes based 

on the highest Chi/Q value (represented by 

Station 4)

Table D-6 

4.5 OCCUPATIONAL EXTERNAL DOSE

There are two potential sources of external exposures received by workers at the Y-12 facility:
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 31 of 50

1. Exposures from the deposition of radionuclides released as a consequence of facility 

operations,

2. Exposures received from radiation levels emanating from buildings and storage areas.

4.5.1

Environmental monitoring of external exposures was performed at health physics monitoring stations 

and is reported in the Annual Site Environmental Reports. Prior to 1983, the only health physics 

monitoring stations for Y-12 were located off site, and consequently were not useful for estimating 

worker exposures. No measurements of external exposures were reported for the twelve on site 

stations at Y-12, which began operations in 1983. With the exception of the limited data from 

environmental monitoring reports, there are two major characterizations of external exposures that 

have been performed for Y-12. A series of aerial radiological surveys was performed in 1973-1974, 

1980, 1989 and 1992 for the ORR that included Y-12. These surveys consisted of a reservation wide, 

high level survey and low-level facility specific surveys. The second major characterization was 

performed from 1985 to 1987 and involved an outdoor radiological and chemical scoping survey of the 

800+ acres occupied by the Y-12 facility. This survey included both radiological and chemical 

assessments and included measurements of both gamma ray exposure rates and the collection of 

surface soil samples. The purpose of the scoping survey was to locate and prioritize areas of concern 

from both a worker health and safety and from an environmental assessment standpoint. The 

approach, results and relative merits of both efforts are discussed below. 

Data Availability

4.5.2

Aerial Radiological Survey 1973–1974 (EG&G 1976)

Range of Exposures from Aerial Surveys

The survey consisted of airborne measurements of both man-made and natural radioisotopes in and 

around the three DOE facilities as well as surrounding areas that are not part of the ORR. Results 

were presented as radiation intensity isopleths that were superimposed onto aerial photographs. 

Aerial measurements were related to exposure levels at one meter above ground. The natural 

background levels were estimated to vary between 4 to 6 μR h-1 for Y-12. This does not include an 

exposure rate of 3.8 μR h-1 from cosmic radiation. 

Radiation levels at Y-12 can be separated into five distinct areas of higher than background 

exposures. The highest exposure range of 50-100 μR h-1 was centered around a waste disposal 

pond located at the west end of the facility. Higher areas were inferred from the 208Tl peak 

(attributable to thorium). These exposures were attributed to a coal pile. Additional 208Tl isopleths 

were attributed to thorium storage areas producing maximum exposure values ranging from 13 to 25 

μR h-1. Tons of 238U stored at the west end of Y-12 produced maximum levels ranging from 50 to 100 

μR h-1. Exposure rates in these five areas range from 1.5 to 100 μR h-1 over approximately 50% of 

the site. 

Other sources included collimated sources and x-ray machines located in buildings. Multiple flyovers 

indicate that these sources were not in constant operation. 

Aerial Radiological Survey 1980 (EG&G 1984)

The focus of the second aerial survey was to identify specific radiological sources including 60Co, 

234mPa and 137Cs. Isopleths for the vicinity of the Y-12 area show three major areas of elevated 

exposure rates. All are located towards the west end of the facility with the highest isopleths relating 

to an exposure rate of 100 to 200 μR h-1. The resolution of the isopleths prevents a determination of 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 32 of 50

exact location of these sources of higher exposure. These areas of higher exposure are limited to the 

west side of the facility. The remainder of Y-12 is within the 11.8 to 20 μR h-1 exposure range.

Aerial Radiological Survey 1989 (EG&G 1992)

The exposure rates for the Y-12 facility show a reduction in the number of areas of elevated readings 

as compared to the 1980 survey. The highest exposures are still localized over a small area at the 

west end of the site. The net spectra are dominated by the 234mPa photopeak indicating the presence 

of DU. Maximum exposures ranged from 35 to 80 μR hr-1 for this area. Two smaller areas in the 14 

to 35 μR h-1 range were noted in the center portion of the site. The spectra for one of these areas are 

related to the 235U and appear to be centered over the production areas. This photopeak was not 

observed during the previous flyover. The net spectra for the other area are indicative of Th. 

Aerial Radiological Survey 1992 (EG&G 1993)

The 1992 survey identified six areas within the Y-12 complex with elevated exposure rates. Three of 

these areas show evidence of 234mPa, indicating that the source is DU. The highest area is located 

toward the west end of the site with the maximum isopleth range of 20 to 50 μR h-1. This area of 

concern, attributed to DU, is likely to be the same source area (waste disposal area) as identified in 

previous surveys. The maximum isopleths for the other 5 areas range from 13 to 20 μR h-1. The 

spectra for two of these areas show the characteristic photopeak for 235U and are located over areas 

that are either associated with production or material storage. The remainder of the site is 

encompassed by isopleths ranging from 8 to 13 μR h-1. 

4.5.3

An outdoor radiological and chemical scoping survey was conducted at Y-12 between September 

1985 and May 1987 (Foley and Carrier 1990). The survey included the approximately 800 acres of 

the plant, as well as adjacent areas where emission depositions likely occurred. The purpose of the 

survey was to locate and prioritize areas of concern from both a worker health and safety and from an 

environmental assessment standpoint. The survey included measurements of both gamma ray 

exposure rates and collection of surface soil samples. The measurement of gamma ray exposure 

rates was made by direct measurements at grid locations and by scans of areas within grid blocks.

Results of 1987 Scoping Survey

The entire site was initially partitioned into 22 priority areas. Five areas were later sub-divided to form 

additional survey areas for a total of 27 priority areas. The priority areas were established by Y-12 

Management to encompass logical units of operation and to maintain manageable survey grids. Each 

area was further divided into grid blocks according to the Y-12 master grid plan. Each block varied in 

size according to the degree of contamination expected. Grid blocks with closely spaced buildings 

were sized as 100’x100’; open areas were divided into 200’x200’ grid blocks.

Exposure measurements for each grid block comprised of a range of exposure levels and direct 

readings at specific grid intersections. Each grid block was thoroughly scanned with a portable 

gamma scintillation meter (11⁄4” x 11⁄2” NaI probe). The scan produced a range of exposure levels for 

each grid block. Direct exposure measurements were also made at each grid line intersection. All 

gamma measurements were made at ground surface.

The results of the scans and direct measurements were tabulated for each of the 27 priority areas. 

Ranges of measurements were provided in the report, but no further analysis of the data was 

performed. To generate a site wide estimate for gamma ray exposure, values were assembled for 

each of the 1787 grid blocks. Values for each grid block were presented as direct measurements 

taken at each grid point and as a range of exposures measured during the scan. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 33 of 50

4.5.4

The four aerial surveys discussed above present reasonable ranges of elevated external exposures. 

However, the purpose of these surveys was to identify specific sources of higher than background 

radiation levels. The focus of the latter aerial surveys was to isolate and identify sources such as 

waste pits and storage areas. The resulting isopleths from these surveys have relatively poor 

resolution and are not reliable for estimating a site wide average exposure rate. Some of the major 

sources identified by the aerial surveys were attributed to collimated sources that were not in constant 

operation. In addition, the isopleths generated by these surveys are dominated by the high radiation 

source areas and provide little or no definition for localized areas. Interpreting a site wide average 

was not possible from these aerial surveys. 

Estimated External Exposures for Y-12 Workers

Because of the limitations of the aerial surveys, it was decided to use the results of the 1987 outdoor 

scoping survey for estimating external exposures for all years from 1948 to 2002. The scoping 

survey is a comprehensive assessment of radiation exposures and encompasses all areas of the site. 

There are 1787 grids and the resolution of the grids (100 feet x100 feet to 200 feet x 200 feet) 

ensures that all localized hot-spots are included. The purpose of the scoping survey was to locate 

and prioritize areas of concern from both a worker health and safety and from an environmental 

assessment standpoint and is therefore most relevant to assessing worker exposure. 

For this Technical Basis Document, the highest exposure reading from either the scan or the direct 

measurement presented in the scoping survey was used. This approach presented the most 

conservative method of estimating exposures and ensures that areas of high exposure levels within 

each grid were included in the site wide average. It was noted that numerous grid blocks exhibited 

high exposure readings, but these areas were not subjected to direct measurements. Higher readings 

were attributed to either shine from nearby buildings and storage areas or to localized hot-spots. 

By utilizing the highest direct exposure value from either the scans or the direct readings, exposures 

attributable to shine or localized hot-spots were included in the assessment. Since the purpose of this 

assessment is to estimate doses received from ambient external radiation, neglecting these areas of 

high exposure would not encompass external exposures potentially received by people working in 

these areas. 

The 1787 exposure measurements used for this analysis ranged from 4 to 1,500 μR h-1. However 

88% of the data was less than 100 μR h-1 indicating a definitive skew to the data, and this was 

confirmed with plots of all data. Therefore, a lognormal distribution was used for the range of 

exposure rates presented in the scoping survey. The measured exposure rates were converted to 

dose equivalent rates assuming a quality factor of one (1). The data are shown in Table 4.4.4-1 

below.

Table 4.4.4-1. External environmental dose equivalent 

rates outside buildings on Y-12 site from 1948-2002.

Dose equivalent

rates (μrem h-1)

Minimum 4

Maximum 1500

Geometric Mean (GM) 21

Geometric Standard Deviation (GSD) 3.0

50th percentile 21

95th percentile 129
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 34 of 50

Based on the findings and recommendations of NIOSH and the Advisory Board on Radiation and 

Worker Health, the Secretary of Health and Human Services has determined that for the time period 

from March 1943 through December 1947, the only radiological exposures at Y-12 for which dose can 

be reconstructed are that those that resulted from occupational medical x-rays. Consequently 

environmental exposures are not reconstructed for those years.

The highest exposure readings were generally attributed to the shine emanating from nearby 

buildings, storage areas or waste pits. Although these readings are not indicative of the level of 

radioactivity in soils and surfaces, contributions from shine are valid sources of exposure for workers. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 35 of 50

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ChemRisk Doc 1884

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ChemRisk Doc 1878

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ChemRisk Doc 3182

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UCC 1978. Environmental Monitoring Report, United States Department of Energy Oak Ridge 

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GLOSSARY

BEING PREPARED
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 42 of 50

ATTACHMENT D

OCCUPATIONAL ENVIRONMENTAL DOSE

LIST OF TABLES

D-1 Calculated 234/235U and 238U air concentrations and intakes for Station 2 ............................. 44

D-2 Calculated 234/235U and 238U air concentrations and intakes for Station 4 ............................. 45

D-3 Calculated 234/235U and 238U air concentrations and intakes for Station 8 ............................. 46

D-4 Calculated 234/235U and 238U air concentrations and intakes for Station 12 ........................... 47

D-5 Site wide 234/235U and 238U air concentrations and Intakes based on average 

air concentrations for Stations 2, 4, 8 and 12 ...................................................................... 48

D-6 Maximum 234/235U and 238U air concentrations and intakes................................................... 49

D-7 External dose rates outside buildings on Y-12 site .............................................................. 50

D1.0 OCCUPATIONAL ENVIRONMENTAL DOSE FOR UNMONITORED WORKERS

The occupational environmental dose received by unmonitored workers is limited to exposures 

received while outside buildings and within the perimeter of the Y-12 Plant. Buildings and other 

operational units occupy the vast majority of the land area at Y-12. This assessment will quantify 

exposure for unmonitored workers who either work outdoors or otherwise spend time outside 

buildings. Based on the exposure assessment, the two exposure pathways are:

1. Inhalation of uranium in ambient air due to operational releases,

2. Direct external radiation exposure from radionuclides in soils and outdoor surfaces, as well 

as shine from buildings and operational units.

Based on the findings and recommendations of NIOSH and the Advisory Board on Radiation and 

Worker Health, the Secretary of Health and Human Services has determined that for the time period 

from March 1943 through December 1947, the only radiological exposures at Y-12 for which dose can 

be reconstructed are that those that resulted from occupational medical x-rays.

D2.0 INTAKE OF RADIONUCLIDES FROM ON SITE RELEASES OF RADIONUCLIDES

Although other radionuclides have been present at Y-12, the primary source of airborne radioactive 

material is uranium from the various operations that have occurred over the years. Thus, intakes 

have been calculated only for 234/235U and 238U. Only four monitoring stations are located on Y-12, so 

intakes have been calculated only for these locations (Tables D-1 to D-4). In addition, site-wide 

average concentrations based on the four stations have been calculated and are in Table D-5. The 

maximum intake is shown in Table D-6. 

The on site concentrations of 234/235U and 238U were estimated based on an empirical approach. The 

air concentrations and intakes were estimated using the 50th and 95th percentile values for the 

empirical dispersion coefficient (Chi/Q) for each station. Air concentrations (becquerel/cubic meter

[Bq m-3]) for all years from 1948 to 2002 were estimated based on the quantities of uranium released. 

Intakes (Bq y-1) were estimated from the air concentrations based on an exposure assumption of 

2000 h y-1 and an inhalation rate of 1.2 m3

 h-1. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 43 of 50

Intakes were estimated for four locations within the boundary of the facility. A site-wide average was 

also calculated from these four locations. In addition, maximum air concentrations and intakes are 

presented. 
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 44 of 50

Table D-1. Calculated 234/235U and 238U air concentrations and intakes for Station 2. Station 2 Air Concentrations (Bq m-3

) Station 2 Intake (Bq y-1) 234/235U 238U 234/235U 238U

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 3.12E-05 8.26E-05 4.04E-05 1.07E-04 0.0749 0.1983 0.0969 0.2566

1949 3.12E-05 8.26E-05 4.04E-05 1.07E-04 0.0749 0.1983 0.0969 0.2566

1950 3.12E-05 8.26E-05 4.04E-05 1.07E-04 0.0749 0.1983 0.0969 0.2566

1951 3.12E-05 8.26E-05 4.04E-05 1.07E-04 0.0749 0.1983 0.0969 0.2566

1952 3.12E-05 8.26E-05 4.04E-05 1.07E-04 0.0749 0.1983 0.0969 0.2566

1953 1.23E-04 3.26E-04 2.50E-04 6.61E-04 0.2952 0.7816 0.5993 1.5865

1954 1.06E-04 2.82E-04 2.35E-04 6.22E-04 0.2556 0.6766 0.5640 1.4932

1955 1.08E-04 2.87E-04 2.35E-04 6.22E-04 0.2600 0.6883 0.5640 1.4932

1956 5.88E-04 1.56E-03 1.84E-04 4.86E-04 1.4101 3.7329 0.4407 1.1665

1957 1.06E-03 2.82E-03 1.47E-04 3.89E-04 2.5558 6.7659 0.3525 0.9332

1958 3.19E-03 8.46E-03 3.30E-04 8.75E-04 7.6674 20.2976 0.7932 2.0998

1959 2.18E-03 5.78E-03 3.67E-04 9.72E-04 5.2438 13.8817 0.8813 2.3331

1960 4.46E-04 1.18E-03 5.69E-05 1.51E-04 1.0708 2.8347 0.1366 0.3616

1961 7.16E-04 1.90E-03 7.90E-05 2.09E-04 1.7186 4.5495 0.1895 0.5016

1962 7.73E-04 2.05E-03 8.45E-05 2.24E-04 1.8552 4.9111 0.2027 0.5366

1963 3.86E-04 1.02E-03 1.29E-04 3.40E-04 0.9254 2.4497 0.3085 0.8166

1964 1.25E-04 3.31E-04 1.67E-04 4.42E-04 0.2996 0.7932 0.4010 1.0615

1965 6.26E-04 1.66E-03 3.67E-05 9.72E-05 1.5026 3.9779 0.0881 0.2333

1966 2.00E-04 5.30E-04 5.69E-05 1.51E-04 0.4803 1.2715 0.1366 0.3616

1967 9.18E-05 2.43E-04 2.02E-05 5.35E-05 0.2203 0.5833 0.0485 0.1283

1968 4.04E-05 1.07E-04 2.75E-05 7.29E-05 0.0969 0.2566 0.0661 0.1750

1969 1.78E-04 4.71E-04 1.47E-05 3.89E-05 0.4274 1.1315 0.0353 0.0933

1970 2.92E-04 7.73E-04 1.65E-05 4.37E-05 0.7006 1.8548 0.0397 0.1050

1971 3.80E-04 1.01E-03 3.49E-05 9.24E-05 0.9122 2.4147 0.0837 0.2216

1972 6.72E-04 1.78E-03 5.14E-05 1.36E-04 1.6128 4.2695 0.1234 0.3266

1973 5.93E-04 1.57E-03 2.39E-05 6.32E-05 1.4233 3.7679 0.0573 0.1516

1974 5.14E-05 1.36E-04 1.29E-05 3.40E-05 0.1234 0.3266 0.0308 0.0817

1975 9.55E-05 2.53E-04 1.29E-05 3.40E-05 0.2291 0.6066 0.0308 0.0817

1976 6.06E-05 1.60E-04 1.29E-05 3.40E-05 0.1454 0.3850 0.0308 0.0817

1977 2.94E-05 7.78E-05 1.29E-05 3.40E-05 0.0705 0.1866 0.0308 0.0817

1978 3.12E-05 8.26E-05 1.29E-05 3.40E-05 0.0749 0.1983 0.0308 0.0817

1979 4.41E-05 1.17E-04 1.29E-05 3.40E-05 0.1058 0.2800 0.0308 0.0817

1980 8.63E-05 2.28E-04 1.29E-05 3.40E-05 0.2071 0.5483 0.0308 0.0817

1981 5.32E-05 1.41E-04 1.29E-05 3.40E-05 0.1278 0.3383 0.0308 0.0817

1982 8.81E-05 2.33E-04 1.29E-05 3.40E-05 0.2115 0.5599 0.0308 0.0817

1983 7.53E-05 1.99E-04 1.29E-05 3.40E-05 0.1807 0.4783 0.0308 0.0817

1984 6.43E-05 1.70E-04 2.02E-05 5.35E-05 0.1542 0.4083 0.0485 0.1283

1985 5.14E-05 1.36E-04 1.29E-05 3.40E-05 0.1234 0.3266 0.0308 0.0817

1986 6.43E-05 1.70E-04 1.29E-05 3.40E-05 0.1542 0.4083 0.0308 0.0817

1987 1.08E-04 2.87E-04 9.18E-06 2.43E-05 0.2600 0.6883 0.0220 0.0583

1988 5.51E-05 1.46E-04 9.18E-06 2.43E-05 0.1322 0.3500 0.0220 0.0583

1989 2.75E-05 7.29E-05 2.57E-06 6.80E-06 0.0661 0.1750 0.0062 0.0163

1990 1.47E-05 3.89E-05 1.29E-06 3.40E-06 0.0353 0.0933 0.0031 0.0082

1991 7.34E-06 1.94E-05 1.84E-06 4.86E-06 0.0176 0.0467 0.0044 0.0117

1992 7.34E-06 1.94E-05 1.10E-06 2.92E-06 0.0176 0.0467 0.0026 0.0070

1993 5.51E-06 1.46E-05 5.51E-07 1.46E-06 0.0132 0.0350 0.0013 0.0035

1994 5.51E-06 1.46E-05 3.67E-07 9.72E-07 0.0132 0.0350 0.0009 0.0023

1995 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

1996 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

1997 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

1998 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

1999 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

2000 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

2001 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024

2002 3.67E-06 9.72E-06 3.86E-07 1.02E-06 0.0088 0.0233 0.0009 0.0024
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 45 of 50

Table D-2. Calculated 234/235U and 238U air concentrations and intakes for Station 4. Station 4 Air Concentration (Bq m-3

) Station 4 Intake (Bq y-1) 234/235U 238U 234/235U 238U

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1949 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1950 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1951 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1952 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1953 3.57E-04 2.16E-03 7.25E-04 4.39E-03 0.8575 5.1946 1.7406 10.5442

1954 3.09E-04 1.87E-03 6.83E-04 4.13E-03 0.7423 4.4968 1.6382 9.9239

1955 3.15E-04 1.91E-03 6.83E-04 4.13E-03 0.7551 4.5743 1.6382 9.9239

1956 1.71E-03 1.03E-02 5.33E-04 3.23E-03 4.0955 24.8098 1.2798 7.7531

1957 3.09E-03 1.87E-02 4.27E-04 2.58E-03 7.4230 44.9678 1.0239 6.2025

1958 9.28E-03 5.62E-02 9.60E-04 5.81E-03 22.2691 134.9034 2.3037 13.9555

1959 6.35E-03 3.84E-02 1.07E-03 6.46E-03 15.2300 92.2615 2.5597 15.5061

1960 1.30E-03 7.85E-03 1.65E-04 1.00E-03 3.1100 18.8400 0.3967 2.4035

1961 2.08E-03 1.26E-02 2.29E-04 1.39E-03 4.9914 30.2370 0.5503 3.3338

1962 2.25E-03 1.36E-02 2.45E-04 1.49E-03 5.3881 32.6404 0.5887 3.5664

1963 1.12E-03 6.78E-03 3.73E-04 2.26E-03 2.6877 16.2814 0.8959 5.4271

1964 3.63E-04 2.20E-03 4.85E-04 2.94E-03 0.8703 5.2721 1.1646 7.0553

1965 1.82E-03 1.10E-02 1.07E-04 6.46E-04 4.3642 26.4380 0.2560 1.5506

1966 5.81E-04 3.52E-03 1.65E-04 1.00E-03 1.3950 8.4508 0.3967 2.4035

1967 2.67E-04 1.62E-03 5.87E-05 3.55E-04 0.6399 3.8765 0.1408 0.8528

1968 1.17E-04 7.11E-04 8.00E-05 4.85E-04 0.2816 1.7057 0.1920 1.1630

1969 5.17E-04 3.13E-03 4.27E-05 2.58E-04 1.2414 7.5205 0.1024 0.6202

1970 8.48E-04 5.14E-03 4.80E-05 2.91E-04 2.0349 12.3274 0.1152 0.6978

1971 1.10E-03 6.69E-03 1.01E-04 6.14E-04 2.6493 16.0489 0.2432 1.4731

1972 1.95E-03 1.18E-02 1.49E-04 9.05E-04 4.6842 28.3762 0.3584 2.1709

1973 1.72E-03 1.04E-02 6.93E-05 4.20E-04 4.1339 25.0424 0.1664 1.0079

1974 1.49E-04 9.05E-04 3.73E-05 2.26E-04 0.3584 2.1709 0.0896 0.5427

1975 2.77E-04 1.68E-03 3.73E-05 2.26E-04 0.6655 4.0316 0.0896 0.5427

1976 1.76E-04 1.07E-03 3.73E-05 2.26E-04 0.4223 2.5585 0.0896 0.5427

1977 8.53E-05 5.17E-04 3.73E-05 2.26E-04 0.2048 1.2405 0.0896 0.5427

1978 9.07E-05 5.49E-04 3.73E-05 2.26E-04 0.2176 1.3180 0.0896 0.5427

1979 1.28E-04 7.75E-04 3.73E-05 2.26E-04 0.3072 1.8607 0.0896 0.5427

1980 2.51E-04 1.52E-03 3.73E-05 2.26E-04 0.6015 3.6439 0.0896 0.5427

1981 1.55E-04 9.37E-04 3.73E-05 2.26E-04 0.3712 2.2484 0.0896 0.5427

1982 2.56E-04 1.55E-03 3.73E-05 2.26E-04 0.6143 3.7215 0.0896 0.5427

1983 2.19E-04 1.32E-03 3.73E-05 2.26E-04 0.5247 3.1788 0.0896 0.5427

1984 1.87E-04 1.13E-03 5.87E-05 3.55E-04 0.4479 2.7136 0.1408 0.8528

1985 1.49E-04 9.05E-04 3.73E-05 2.26E-04 0.3584 2.1709 0.0896 0.5427

1986 1.87E-04 1.13E-03 3.73E-05 2.26E-04 0.4479 2.7136 0.0896 0.5427

1987 3.15E-04 1.91E-03 2.67E-05 1.62E-04 0.7551 4.5743 0.0640 0.3877

1988 1.60E-04 9.69E-04 2.67E-05 1.62E-04 0.3840 2.3259 0.0640 0.3877

1989 8.00E-05 4.85E-04 7.47E-06 4.52E-05 0.1920 1.1630 0.0179 0.1085

1990 4.27E-05 2.58E-04 3.73E-06 2.26E-05 0.1024 0.6202 0.0090 0.0543

1991 2.13E-05 1.29E-04 5.33E-06 3.23E-05 0.0512 0.3101 0.0128 0.0775

1992 2.13E-05 1.29E-04 3.20E-06 1.94E-05 0.0512 0.3101 0.0077 0.0465

1993 1.60E-05 9.69E-05 1.60E-06 9.69E-06 0.0384 0.2326 0.0038 0.0233

1994 1.60E-05 9.69E-05 1.07E-06 6.46E-06 0.0384 0.2326 0.0026 0.0155

1995 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1996 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1997 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1998 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1999 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2000 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2001 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2002 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 46 of 50

Table D-3. Calculated 234/235U and 238U air concentrations and intakes for Station 8. Station 8 Air Concentration (Bq m-3

) Station 8 Intake (Bq y-1) 234/235U 238U 234/235U 238U

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 7.91E-05 4.74E-04 1.02E-04 6.13E-04 0.1898 1.1368 0.2457 1.4711

1949 7.91E-05 4.74E-04 1.02E-04 6.13E-04 0.1898 1.1368 0.2457 1.4711

1950 7.91E-05 4.74E-04 1.02E-04 6.13E-04 0.1898 1.1368 0.2457 1.4711

1951 7.91E-05 4.74E-04 1.02E-04 6.13E-04 0.1898 1.1368 0.2457 1.4711

1952 7.91E-05 4.74E-04 1.02E-04 6.13E-04 0.1898 1.1368 0.2457 1.4711

1953 3.12E-04 1.87E-03 6.33E-04 3.79E-03 0.7482 4.4802 1.5187 9.0941

1954 2.70E-04 1.62E-03 5.96E-04 3.57E-03 0.6477 3.8784 1.4293 8.5592

1955 2.75E-04 1.64E-03 5.96E-04 3.57E-03 0.6588 3.9452 1.4293 8.5592

1956 1.49E-03 8.92E-03 4.65E-04 2.79E-03 3.5733 21.3979 1.1167 6.6869

1957 2.70E-03 1.62E-02 3.72E-04 2.23E-03 6.4766 38.7837 0.8933 5.3495

1958 8.10E-03 4.85E-02 8.37E-04 5.02E-03 19.4298 116.3512 2.0100 12.0363

1959 5.54E-03 3.32E-02 9.31E-04 5.57E-03 13.2882 79.5735 2.2333 13.3737

1960 1.13E-03 6.77E-03 1.44E-04 8.64E-04 2.7135 16.2490 0.3462 2.0729

1961 1.81E-03 1.09E-02 2.00E-04 1.20E-03 4.3550 26.0787 0.4802 2.8753

1962 1.96E-03 1.17E-02 2.14E-04 1.28E-03 4.7011 28.1516 0.5137 3.0760

1963 9.77E-04 5.85E-03 3.26E-04 1.95E-03 2.3450 14.0424 0.7817 4.6808

1964 3.16E-04 1.89E-03 4.23E-04 2.54E-03 0.7593 4.5471 1.0162 6.0850

1965 1.59E-03 9.50E-03 9.31E-05 5.57E-04 3.8078 22.8022 0.2233 1.3374

1966 5.07E-04 3.04E-03 1.44E-04 8.64E-04 1.2172 7.2887 0.3462 2.0729

1967 2.33E-04 1.39E-03 5.12E-05 3.06E-04 0.5583 3.3434 0.1228 0.7356

1968 1.02E-04 6.13E-04 6.98E-05 4.18E-04 0.2457 1.4711 0.1675 1.0030

1969 4.51E-04 2.70E-03 3.72E-05 2.23E-04 1.0832 6.4862 0.0893 0.5349

1970 7.40E-04 4.43E-03 4.19E-05 2.51E-04 1.7755 10.6321 0.1005 0.6018

1971 9.63E-04 5.77E-03 8.84E-05 5.29E-04 2.3115 13.8418 0.2122 1.2705

1972 1.70E-03 1.02E-02 1.30E-04 7.80E-04 4.0870 24.4739 0.3127 1.8723

1973 1.50E-03 9.00E-03 6.05E-05 3.62E-04 3.6068 21.5985 0.1452 0.8693

1974 1.30E-04 7.80E-04 3.26E-05 1.95E-04 0.3127 1.8723 0.0782 0.4681

1975 2.42E-04 1.45E-03 3.26E-05 1.95E-04 0.5807 3.4772 0.0782 0.4681

1976 1.54E-04 9.19E-04 3.26E-05 1.95E-04 0.3685 2.2067 0.0782 0.4681

1977 7.44E-05 4.46E-04 3.26E-05 1.95E-04 0.1787 1.0699 0.0782 0.4681

1978 7.91E-05 4.74E-04 3.26E-05 1.95E-04 0.1898 1.1368 0.0782 0.4681

1979 1.12E-04 6.69E-04 3.26E-05 1.95E-04 0.2680 1.6048 0.0782 0.4681

1980 2.19E-04 1.31E-03 3.26E-05 1.95E-04 0.5248 3.1428 0.0782 0.4681

1981 1.35E-04 8.08E-04 3.26E-05 1.95E-04 0.3238 1.9392 0.0782 0.4681

1982 2.23E-04 1.34E-03 3.26E-05 1.95E-04 0.5360 3.2097 0.0782 0.4681

1983 1.91E-04 1.14E-03 3.26E-05 1.95E-04 0.4578 2.7416 0.0782 0.4681

1984 1.63E-04 9.75E-04 5.12E-05 3.06E-04 0.3908 2.3404 0.1228 0.7356

1985 1.30E-04 7.80E-04 3.26E-05 1.95E-04 0.3127 1.8723 0.0782 0.4681

1986 1.63E-04 9.75E-04 3.26E-05 1.95E-04 0.3908 2.3404 0.0782 0.4681

1987 2.75E-04 1.64E-03 2.33E-05 1.39E-04 0.6588 3.9452 0.0558 0.3343

1988 1.40E-04 8.36E-04 2.33E-05 1.39E-04 0.3350 2.0061 0.0558 0.3343

1989 6.98E-05 4.18E-04 6.51E-06 3.90E-05 0.1675 1.0030 0.0156 0.0936

1990 3.72E-05 2.23E-04 3.26E-06 1.95E-05 0.0893 0.5349 0.0078 0.0468

1991 1.86E-05 1.11E-04 4.65E-06 2.79E-05 0.0447 0.2675 0.0112 0.0669

1992 1.86E-05 1.11E-04 2.79E-06 1.67E-05 0.0447 0.2675 0.0067 0.0401

1993 1.40E-05 8.36E-05 1.40E-06 8.36E-06 0.0335 0.2006 0.0033 0.0201

1994 1.40E-05 8.36E-05 9.31E-07 5.57E-06 0.0335 0.2006 0.0022 0.0134

1995 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

1996 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

1997 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

1998 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

1999 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

2000 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

2001 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140

2002 9.31E-06 5.57E-05 9.77E-07 5.85E-06 0.0223 0.1337 0.0023 0.0140
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 47 of 50

Table D-4. Calculated 234/235U and 238U air concentrations and intakes for Station 12. Station 12 Air Concentration (Bq m-3

) Station 12 Intake (Bq y-1) 234/235U 238U 234/235U 238U

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 2.85E-05 1.21E-04 3.69E-05 1.56E-04 0.0685 0.2897 0.0886 0.3748

1949 2.85E-05 1.21E-04 3.69E-05 1.56E-04 0.0685 0.2897 0.0886 0.3748

1950 2.85E-05 1.21E-04 3.69E-05 1.56E-04 0.0685 0.2897 0.0886 0.3748

1951 2.85E-05 1.21E-04 3.69E-05 1.56E-04 0.0685 0.2897 0.0886 0.3748

1952 2.85E-05 1.21E-04 3.69E-05 1.56E-04 0.0685 0.2897 0.0886 0.3748

1953 1.12E-04 4.76E-04 2.28E-04 9.66E-04 0.2700 1.1416 0.5480 2.3172

1954 9.74E-05 4.12E-04 2.15E-04 9.09E-04 0.2337 0.9882 0.5157 2.1809

1955 9.90E-05 4.19E-04 2.15E-04 9.09E-04 0.2377 1.0053 0.5157 2.1809

1956 5.37E-04 2.27E-03 1.68E-04 7.10E-04 1.2893 5.4523 0.4029 1.7039

1957 9.74E-04 4.12E-03 1.34E-04 5.68E-04 2.3369 9.8824 0.3223 1.3631

1958 2.92E-03 1.24E-02 3.02E-04 1.28E-03 7.0107 29.6471 0.7252 3.0669

1959 2.00E-03 8.45E-03 3.36E-04 1.42E-03 4.7947 20.2759 0.8058 3.4077

1960 4.08E-04 1.73E-03 5.20E-05 2.20E-04 0.9791 4.1404 0.1249 0.5282

1961 6.55E-04 2.77E-03 7.22E-05 3.05E-04 1.5714 6.6450 0.1733 0.7327

1962 7.07E-04 2.99E-03 7.72E-05 3.27E-04 1.6963 7.1732 0.1853 0.7838

1963 3.53E-04 1.49E-03 1.18E-04 4.97E-04 0.8461 3.5781 0.2820 1.1927

1964 1.14E-04 4.83E-04 1.53E-04 6.46E-04 0.2740 1.1586 0.3667 1.5505

1965 5.72E-04 2.42E-03 3.36E-05 1.42E-04 1.3739 5.8102 0.0806 0.3408

1966 1.83E-04 7.74E-04 5.20E-05 2.20E-04 0.4392 1.8572 0.1249 0.5282

1967 8.39E-05 3.55E-04 1.85E-05 7.81E-05 0.2015 0.8519 0.0443 0.1874

1968 3.69E-05 1.56E-04 2.52E-05 1.06E-04 0.0886 0.3748 0.0604 0.2556

1969 1.63E-04 6.89E-04 1.34E-05 5.68E-05 0.3908 1.6527 0.0322 0.1363

1970 2.67E-04 1.13E-03 1.51E-05 6.39E-05 0.6406 2.7091 0.0363 0.1533

1971 3.48E-04 1.47E-03 3.19E-05 1.35E-04 0.8340 3.5270 0.0766 0.3237

1972 6.14E-04 2.60E-03 4.70E-05 1.99E-04 1.4747 6.2361 0.1128 0.4771

1973 5.42E-04 2.29E-03 2.18E-05 9.23E-05 1.3014 5.5035 0.0524 0.2215

1974 4.70E-05 1.99E-04 1.18E-05 4.97E-05 0.1128 0.4771 0.0282 0.1193

1975 8.73E-05 3.69E-04 1.18E-05 4.97E-05 0.2095 0.8860 0.0282 0.1193

1976 5.54E-05 2.34E-04 1.18E-05 4.97E-05 0.1330 0.5623 0.0282 0.1193

1977 2.69E-05 1.14E-04 1.18E-05 4.97E-05 0.0645 0.2726 0.0282 0.1193

1978 2.85E-05 1.21E-04 1.18E-05 4.97E-05 0.0685 0.2897 0.0282 0.1193

1979 4.03E-05 1.70E-04 1.18E-05 4.97E-05 0.0967 0.4089 0.0282 0.1193

1980 7.89E-05 3.34E-04 1.18E-05 4.97E-05 0.1894 0.8008 0.0282 0.1193

1981 4.87E-05 2.06E-04 1.18E-05 4.97E-05 0.1168 0.4941 0.0282 0.1193

1982 8.06E-05 3.41E-04 1.18E-05 4.97E-05 0.1934 0.8179 0.0282 0.1193

1983 6.88E-05 2.91E-04 1.18E-05 4.97E-05 0.1652 0.6986 0.0282 0.1193

1984 5.88E-05 2.48E-04 1.85E-05 7.81E-05 0.1410 0.5964 0.0443 0.1874

1985 4.70E-05 1.99E-04 1.18E-05 4.97E-05 0.1128 0.4771 0.0282 0.1193

1986 5.88E-05 2.48E-04 1.18E-05 4.97E-05 0.1410 0.5964 0.0282 0.1193

1987 9.90E-05 4.19E-04 8.39E-06 3.55E-05 0.2377 1.0053 0.0201 0.0852

1988 5.04E-05 2.13E-04 8.39E-06 3.55E-05 0.1209 0.5112 0.0201 0.0852

1989 2.52E-05 1.06E-04 2.35E-06 9.94E-06 0.0604 0.2556 0.0056 0.0239

1990 1.34E-05 5.68E-05 1.18E-06 4.97E-06 0.0322 0.1363 0.0028 0.0119

1991 6.72E-06 2.84E-05 1.68E-06 7.10E-06 0.0161 0.0682 0.0040 0.0170

1992 6.72E-06 2.84E-05 1.01E-06 4.26E-06 0.0161 0.0682 0.0024 0.0102

1993 5.04E-06 2.13E-05 5.04E-07 2.13E-06 0.0121 0.0511 0.0012 0.0051

1994 5.04E-06 2.13E-05 3.36E-07 1.42E-06 0.0121 0.0511 0.0008 0.0034

1995 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

1996 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

1997 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

1998 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

1999 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

2000 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

2001 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036

2002 3.36E-06 1.42E-05 3.53E-07 1.49E-06 0.0081 0.0341 0.0008 0.0036
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 48 of 50

Table D-5. Site wide 234/235U and 238U air concentrations and intakes based on average air 

concentrations for Stations 2, 4, 8 and 12. Site Wide Average Air Concentration (Bq m-3

) Site Wide Average Intake (Bq y-1) 234/235U 238U 234/235U 238U 

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 5.74E-05 3.07E-04 7.43E-05 3.97E-04 0.1377 0.7357 0.1782 0.9521

1949 5.74E-05 3.07E-04 7.43E-05 3.97E-04 0.1377 0.7357 0.1782 0.9521

1950 5.74E-05 3.07E-04 7.43E-05 3.97E-04 0.1377 0.7357 0.1782 0.9521

1951 5.74E-05 3.07E-04 7.43E-05 3.97E-04 0.1377 0.7357 0.1782 0.9521

1952 5.74E-05 3.07E-04 7.43E-05 3.97E-04 0.1377 0.7357 0.1782 0.9521

1953 2.26E-04 1.21E-03 4.59E-04 2.45E-03 0.5427 2.8995 1.1016 5.8855

1954 1.96E-04 1.05E-03 4.32E-04 2.31E-03 0.4698 2.5100 1.0368 5.5393

1955 1.99E-04 1.06E-03 4.32E-04 2.31E-03 0.4779 2.5533 1.0368 5.5393

1956 1.08E-03 5.77E-03 3.38E-04 1.80E-03 2.5920 13.8482 0.8100 4.3276

1957 1.96E-03 1.05E-02 2.70E-04 1.44E-03 4.6981 25.0999 0.6480 3.4621

1958 5.87E-03 3.14E-02 6.08E-04 3.25E-03 14.0943 75.2998 1.4580 7.7896

1959 4.02E-03 2.15E-02 6.75E-04 3.61E-03 9.6392 51.4982 1.6200 8.6552

1960 8.20E-04 4.38E-03 1.05E-04 5.59E-04 1.9683 10.5160 0.2511 1.3415

1961 1.32E-03 7.03E-03 1.45E-04 7.75E-04 3.1591 16.8775 0.3483 1.8609

1962 1.42E-03 7.59E-03 1.55E-04 8.29E-04 3.4102 18.2191 0.3726 1.9907

1963 7.09E-04 3.79E-03 2.36E-04 1.26E-03 1.7010 9.0879 0.5670 3.0293

1964 2.30E-04 1.23E-03 3.07E-04 1.64E-03 0.5508 2.9428 0.7371 3.9381

1965 1.15E-03 6.15E-03 6.75E-05 3.61E-04 2.7621 14.7570 0.1620 0.8655

1966 3.68E-04 1.97E-03 1.05E-04 5.59E-04 0.8829 4.7171 0.2511 1.3415

1967 1.69E-04 9.02E-04 3.71E-05 1.98E-04 0.4050 2.1638 0.0891 0.4760

1968 7.43E-05 3.97E-04 5.06E-05 2.70E-04 0.1782 0.9521 0.1215 0.6491

1969 3.27E-04 1.75E-03 2.70E-05 1.44E-04 0.7857 4.1977 0.0648 0.3462

1970 5.37E-04 2.87E-03 3.04E-05 1.62E-04 1.2879 6.8808 0.0729 0.3895

1971 6.99E-04 3.73E-03 6.41E-05 3.43E-04 1.6767 8.9581 0.1539 0.8222

1972 1.24E-03 6.60E-03 9.45E-05 5.05E-04 2.9647 15.8389 0.2268 1.2117

1973 1.09E-03 5.82E-03 4.39E-05 2.34E-04 2.6163 13.9781 0.1053 0.5626

1974 9.45E-05 5.05E-04 2.36E-05 1.26E-04 0.2268 1.2117 0.0567 0.3029

1975 1.76E-04 9.38E-04 2.36E-05 1.26E-04 0.4212 2.2503 0.0567 0.3029

1976 1.11E-04 5.95E-04 2.36E-05 1.26E-04 0.2673 1.4281 0.0567 0.3029

1977 5.40E-05 2.89E-04 2.36E-05 1.26E-04 0.1296 0.6924 0.0567 0.3029

1978 5.74E-05 3.07E-04 2.36E-05 1.26E-04 0.1377 0.7357 0.0567 0.3029

1979 8.10E-05 4.33E-04 2.36E-05 1.26E-04 0.1944 1.0386 0.0567 0.3029

1980 1.59E-04 8.47E-04 2.36E-05 1.26E-04 0.3807 2.0340 0.0567 0.3029

1981 9.79E-05 5.23E-04 2.36E-05 1.26E-04 0.2349 1.2550 0.0567 0.3029

1982 1.62E-04 8.66E-04 2.36E-05 1.26E-04 0.3888 2.0772 0.0567 0.3029

1983 1.38E-04 7.39E-04 2.36E-05 1.26E-04 0.3321 1.7743 0.0567 0.3029

1984 1.18E-04 6.31E-04 3.71E-05 1.98E-04 0.2835 1.5147 0.0891 0.4760

1985 9.45E-05 5.05E-04 2.36E-05 1.26E-04 0.2268 1.2117 0.0567 0.3029

1986 1.18E-04 6.31E-04 2.36E-05 1.26E-04 0.2835 1.5147 0.0567 0.3029

1987 1.99E-04 1.06E-03 1.69E-05 9.02E-05 0.4779 2.5533 0.0405 0.2164

1988 1.01E-04 5.41E-04 1.69E-05 9.02E-05 0.2430 1.2983 0.0405 0.2164

1989 5.06E-05 2.70E-04 4.73E-06 2.52E-05 0.1215 0.6491 0.0113 0.0606

1990 2.70E-05 1.44E-04 2.36E-06 1.26E-05 0.0648 0.3462 0.0057 0.0303

1991 1.35E-05 7.21E-05 3.38E-06 1.80E-05 0.0324 0.1731 0.0081 0.0433

1992 1.35E-05 7.21E-05 2.03E-06 1.08E-05 0.0324 0.1731 0.0049 0.0260

1993 1.01E-05 5.41E-05 1.01E-06 5.41E-06 0.0243 0.1298 0.0024 0.0130

1994 1.01E-05 5.41E-05 6.75E-07 3.61E-06 0.0243 0.1298 0.0016 0.0087

1995 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

1996 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

1997 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

1998 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

1999 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

2000 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

2001 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091

2002 6.75E-06 3.61E-05 7.09E-07 3.79E-06 0.0162 0.0866 0.0017 0.0091
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 49 of 50

Table D-6. Maximum 234/235U and 238U air concentrations and intakes. Station 4 Air Concentration (Bq m-3

) Station 4 Intake (Bq y-1) 234/235U 238U 234/235U 238U

YEAR 50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

50th

Percentile

95th

Percentile

1944 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1945 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1946 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1947 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved

1948 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1949 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1950 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1951 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1952 9.07E-05 5.49E-04 1.17E-04 7.11E-04 0.2176 1.3180 0.2816 1.7057

1953 3.57E-04 2.16E-03 7.25E-04 4.39E-03 0.8575 5.1946 1.7406 10.5442

1954 3.09E-04 1.87E-03 6.83E-04 4.13E-03 0.7423 4.4968 1.6382 9.9239

1955 3.15E-04 1.91E-03 6.83E-04 4.13E-03 0.7551 4.5743 1.6382 9.9239

1956 1.71E-03 1.03E-02 5.33E-04 3.23E-03 4.0955 24.8098 1.2798 7.7531

1957 3.09E-03 1.87E-02 4.27E-04 2.58E-03 7.4230 44.9678 1.0239 6.2025

1958 9.28E-03 5.62E-02 9.60E-04 5.81E-03 22.2691 134.9034 2.3037 13.9555

1959 6.35E-03 3.84E-02 1.07E-03 6.46E-03 15.2300 92.2615 2.5597 15.5061

1960 1.30E-03 7.85E-03 1.65E-04 1.00E-03 3.1100 18.8400 0.3967 2.4035

1961 2.08E-03 1.26E-02 2.29E-04 1.39E-03 4.9914 30.2370 0.5503 3.3338

1962 2.25E-03 1.36E-02 2.45E-04 1.49E-03 5.3881 32.6404 0.5887 3.5664

1963 1.12E-03 6.78E-03 3.73E-04 2.26E-03 2.6877 16.2814 0.8959 5.4271

1964 3.63E-04 2.20E-03 4.85E-04 2.94E-03 0.8703 5.2721 1.1646 7.0553

1965 1.82E-03 1.10E-02 1.07E-04 6.46E-04 4.3642 26.4380 0.2560 1.5506

1966 5.81E-04 3.52E-03 1.65E-04 1.00E-03 1.3950 8.4508 0.3967 2.4035

1967 2.67E-04 1.62E-03 5.87E-05 3.55E-04 0.6399 3.8765 0.1408 0.8528

1968 1.17E-04 7.11E-04 8.00E-05 4.85E-04 0.2816 1.7057 0.1920 1.1630

1969 5.17E-04 3.13E-03 4.27E-05 2.58E-04 1.2414 7.5205 0.1024 0.6202

1970 8.48E-04 5.14E-03 4.80E-05 2.91E-04 2.0349 12.3274 0.1152 0.6978

1971 1.10E-03 6.69E-03 1.01E-04 6.14E-04 2.6493 16.0489 0.2432 1.4731

1972 1.95E-03 1.18E-02 1.49E-04 9.05E-04 4.6842 28.3762 0.3584 2.1709

1973 1.72E-03 1.04E-02 6.93E-05 4.20E-04 4.1339 25.0424 0.1664 1.0079

1974 1.49E-04 9.05E-04 3.73E-05 2.26E-04 0.3584 2.1709 0.0896 0.5427

1975 2.77E-04 1.68E-03 3.73E-05 2.26E-04 0.6655 4.0316 0.0896 0.5427

1976 1.76E-04 1.07E-03 3.73E-05 2.26E-04 0.4223 2.5585 0.0896 0.5427

1977 8.53E-05 5.17E-04 3.73E-05 2.26E-04 0.2048 1.2405 0.0896 0.5427

1978 9.07E-05 5.49E-04 3.73E-05 2.26E-04 0.2176 1.3180 0.0896 0.5427

1979 1.28E-04 7.75E-04 3.73E-05 2.26E-04 0.3072 1.8607 0.0896 0.5427

1980 2.51E-04 1.52E-03 3.73E-05 2.26E-04 0.6015 3.6439 0.0896 0.5427

1981 1.55E-04 9.37E-04 3.73E-05 2.26E-04 0.3712 2.2484 0.0896 0.5427

1982 2.56E-04 1.55E-03 3.73E-05 2.26E-04 0.6143 3.7215 0.0896 0.5427

1983 2.19E-04 1.32E-03 3.73E-05 2.26E-04 0.5247 3.1788 0.0896 0.5427

1984 1.87E-04 1.13E-03 5.87E-05 3.55E-04 0.4479 2.7136 0.1408 0.8528

1985 1.49E-04 9.05E-04 3.73E-05 2.26E-04 0.3584 2.1709 0.0896 0.5427

1986 1.87E-04 1.13E-03 3.73E-05 2.26E-04 0.4479 2.7136 0.0896 0.5427

1987 3.15E-04 1.91E-03 2.67E-05 1.62E-04 0.7551 4.5743 0.0640 0.3877

1988 1.60E-04 9.69E-04 2.67E-05 1.62E-04 0.3840 2.3259 0.0640 0.3877

1989 8.00E-05 4.85E-04 7.47E-06 4.52E-05 0.1920 1.1630 0.0179 0.1085

1990 4.27E-05 2.58E-04 3.73E-06 2.26E-05 0.1024 0.6202 0.0090 0.0543

1991 2.13E-05 1.29E-04 5.33E-06 3.23E-05 0.0512 0.3101 0.0128 0.0775

1992 2.13E-05 1.29E-04 3.20E-06 1.94E-05 0.0512 0.3101 0.0077 0.0465

1993 1.60E-05 9.69E-05 1.60E-06 9.69E-06 0.0384 0.2326 0.0038 0.0233

1994 1.60E-05 9.69E-05 1.07E-06 6.46E-06 0.0384 0.2326 0.0026 0.0155

1995 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1996 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1997 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1998 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

1999 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2000 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2001 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163

2002 1.07E-05 6.46E-05 1.12E-06 6.78E-06 0.0256 0.1551 0.0027 0.0163
Document No. ORAUT-TKBS-0014-4 Revision No. 01 Effective Date: 07/20/2006 Page 50 of 50

D3.0 AMBIENT EXTERNAL DOSE

Ambient radiation levels will be typically measured by the monitored worker’s personal dosimeters. 

However, for the unmonitored worker, external radiation exposures were estimated from prior 

characterization efforts at Y-12.

There are two potential sources of external exposures received by workers at the Y-12 facility:

1. Exposures from the deposition of radionuclides released as a consequence of facility 

operations,

2. Exposures received from radiation levels emanating from buildings and storage areas.

The data from the scoping survey should be used to calculate an external dose for unmonitored 

workers (Foley and Carrier 1990). The dose equivalent rates shown in Table D-7 are based on the 

external exposure rates measured site-wide for the years 1948 to 2002. The exposure rates were 

converted to dose equivalent rates assuming a quality factor of one (1). 

Table D-7. External environmental dose equivalent 

rates outside buildings on Y-12 site from 1948-2002. 

Dose equivalent 

rates (μrem h-1)

Minimum 4

Maximum 1,500

Geometric Mean (GM) 21

Geometric Standard Deviation 

(GSD) 3.0

50th Percentile 21

95th Percentile 129