Page 1 of 32

DOE Review Release 07/18/2022

Internal Dose Overestimates for Facilities 

with Air Sampling Programs

ORAUT-OTIB-0018 Rev. 02

Effective Date: 07/01/2022

Supersedes: Revision 01

Subject Expert(s): Elizabeth M. Brackett

Document Owner 

Approval: Signature on File

John M. Byrne, Document Owner

Approval Date: 06/20/2022

Concurrence: Ali Simpkins Signature on File for

Scott R. Siebert, Objective 3 Manager

Concurrence Date: 06/23/2022

Concurrence: Vickie S. Short Signature on File for

Kate Kimpan, Project Director

Concurrence Date: 06/17/2022

Approval: Signature on File

Timothy D. Taulbee, Associate Director for Science

Approval Date: 07/01/2022

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

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

New Total Rewrite Revision Page Change
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 2 of 32

PUBLICATION RECORD

EFFECTIVE

DATE

REVISION

NUMBER DESCRIPTION

03/18/2005 00 New technical information bulletin to provide information for internal 

dose overestimates for facilities with air sampling programs. 

Incorporates internal review comments. Incorporates changes 

requested by NIOSH, including Attachments B and C. Updates RU 

contaminant levels. Eliminates discussion about ORAUT-OTIB-0002 

related to ORAUT-OTIB-0018. First approved issue. Initiated by 

Donald E. Bihl.

08/09/2005 01 Draft revision to 1) incorporate into Table 4-3 Nb-95 type S and Tc99 type F beta choice and replace RU with U-234 alpha choice, 2) 

add Table 7-2 which provides excretion values for uranium and 

radiostrontium below which the default intakes was still valid, 3) add 

special air concentration values for LANL into Table 4-1.4) correct 

error in the ingestion intake formula #4. Text was added or modified 

in Sections 1.0 through 5.0, 7.0, and Attachment A. No entire 

Sections were deleted. No further changes occurred as a result of 

formal internal review. Incorporates NIOSH review comments. 

Approved issue of Revision 01. Training required: As determined by 

the Task Manager. Initiated by Elizabeth M. Brackett and Donald E. 

Bihl.

07/01/2022 02 Revised to incorporate current DOE derived air concentration values 

per 10 CFR Part 835, address Advisory Board on Radiation and 

Worker Health findings, and incorporate ORAUT-OTIB-0033.

Recycled uranium contaminant ratios were replaced by the 

requirement to use site-specific values. Applicability and limitations 

sections were expanded to be more clear. Incorporates formal 

internal and NIOSH review comments. Constitutes a total rewrite of 

the document. Training required: As determined by the Objective 

Manager. Initiated by John M. Byrne and authored by Elizabeth M. 

Brackett.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 3 of 32

TABLE OF CONTENTS

SECTION TITLE PAGE

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

1.0 Introduction .............................................................................................................................. 7

1.1 Purpose........................................................................................................................ 7

2.0 Background.............................................................................................................................. 7

3.0 Applicability, Limitations, and Assumptions .............................................................................. 9

3.1 Applicability .................................................................................................................. 9

3.2 Limitations .................................................................................................................. 10

3.3 Assumptions............................................................................................................... 10

4.0 Inhalation Intake..................................................................................................................... 11

4.1 Intake Quantity ........................................................................................................... 11

4.2 Choice of Radionuclide............................................................................................... 12

5.0 Ingestion Intake...................................................................................................................... 14

6.0 Application ............................................................................................................................. 14

6.1 Considerations ........................................................................................................... 15

6.1.1 Exposure Potential....................................................................................... 15

6.1.2 Employment Period...................................................................................... 15

6.2 Intake Assignments .................................................................................................... 16

6.2.1 Unmonitored Workers .................................................................................. 16

6.2.1.1 Through 1988............................................................................ 16

6.2.1.2 After 1988.................................................................................. 16

6.2.2 Monitored Workers....................................................................................... 16

6.3 Use During Special Exposure Cohort Periods ............................................................ 16

6.4 Sites with Uranium and Transuranic Areas................................................................. 16

6.4.1 Monitored Workers....................................................................................... 17

6.4.2 Unmonitored Workers .................................................................................. 17

7.0 Uncertainties.......................................................................................................................... 17

References ........................................................................................................................................ 19

ATTACHMENT A VALIDATION OF THE BASIC ASSUMPTION................................................. 22

ATTACHMENT B AIR CONCENTRATION OR OTHER LIMITS BEFORE 1953.......................... 28

ATTACHMENT C EXPOSURE POTENTIALS............................................................................. 29
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 4 of 32

LIST OF TABLES

TABLE TITLE PAGE

2-1 Limiting air concentrations for selected particulates from 1953 to present................................ 8

4-1 Default limiting air concentrations........................................................................................... 11

4-2 Inventory of radionuclides and absorption types..................................................................... 13

6-1 Unmonitored workers .............................................................................................................16

LIST OF FIGURES

FIGURE TITLE PAGE

A-1 Comparison of Y-12 co-exposure and predicted OTIB-0018 type M uranium in urine 

values. ...................................................................................................................................23

A-2 Comparison of Y-12 co-exposure and predicted OTIB-0018 type S uranium in urine 

values. ...................................................................................................................................24

A-3 Comparison of SRS co-exposure and predicted OTIB-0018 types M and S plutonium in 

urine values............................................................................................................................25

A-4 Comparison of Hanford co-exposure and predicted OTIB-0018 types M and S plutonium 

in urine values........................................................................................................................26

A-5 Comparison of Hanford co-exposure and predicted OTIB-0018 type F 90Sr in urine 

values. ...................................................................................................................................27
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 5 of 32

ACRONYMS AND ABBREVIATIONS 

AEC U.S. Atomic Energy Commission

AMAD activity median aerodynamic diameter

AWE atomic weapons employer

BB bronchial region

C.F.R. Code of Federal Regulations

d day

DOE U.S. Department of Energy

dpm disintegrations per minute

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

ET1 extrathoracic region 1

ET2 extrathoracic region 2 (posterior nasal passage, larynx, pharynx, and mouth)

F fast (absorption type)

hr hour

ICRP International Commission on Radiological Protection

LANL Los Alamos National Laboratory

LN(ET) extrathoracic lymph nodes

LN(TH) thoracic lymph nodes

m meter

M moderate (absorption type)

mL milliliter

NBS National Bureau of Standards

NCRP National Council on Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

NU natural uranium

ORAU Oak Ridge Associated Universities

ORAUT ORAU Team

ORNL Oak Ridge National Laboratory

pCi picocurie

RU recycled uranium

S slow (absorption type)

SEC Special Exposure Cohort

SRDB Ref ID Site Research Database Reference Identification (number)

SRS Savannah River Site

SS super slow (absorption type)

TIB technical information bulletin

U.S.C. United States Code
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 6 of 32

yr year

μCi microcurie

μg microgram

μm micrometer

§ section or sections
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 7 of 32

1.0 INTRODUCTION

Technical information bulletins (TIBs) are not official determinations made by the National Institute for 

Occupational Safety and Health (NIOSH) but are rather general working documents that provide 

historical background information and guidance to assist in the preparation of dose reconstructions at 

particular sites or categories of sites. They will be revised in the event additional relevant information 

is obtained about the affected site(s), such as changing scientific understanding of operations, 

processes, or procedures involving radioactive materials. TIBs may be used to assist NIOSH staff in 

the completion of individual dose reconstructions.

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

served a specific purpose at a U.S. Department of Energy (DOE) or Atomic Weapons Employer 

(AWE) facility. It does not mean, nor should it be equated to, an “AWE facility” or a “DOE facility.” The 

terms AWE and DOE facility are defined in 42 United States Code (U.S.C.) § 7384l(5) and (12) of the 

Energy Employees Occupational Illness Compensation Program Act of 2000 (EEOICPA), 

respectively. 

1.1 PURPOSE

The purpose of this TIB is to provide a simplifying overestimate method to facilitate timely processing 

of claims under the EEOICPA. Overestimates can be applied in accordance with guidance given in 

Internal Dose Reconstruction Implementation Guideline [NIOSH 2002], Roadmap to Reconstructing 

Dose [ORAUT 2020a], and Internal Dose Reconstruction [ORAUT 2018]. Restrictions on the 

application of such methods are also described in these documents.

2.0 BACKGROUND

Most DOE sites, including those of its predecessor agencies, had air sampling programs for 

particulate radioactive contamination and, with the exception of short-term unplanned situations, 

controlled air concentrations to limiting values established by the National Council on Radiation 

Protection and Measurements (NCRP) or DOE. The first official national guidelines on air 

concentrations were produced by the NCRP and published in 1953 in National Bureau of Standards 

(NBS) Handbook 52 [NBS 1953]. The NCRP revised its methodology and expanded the list of 

covered radionuclides in 1959, published as NBS Handbook 69 [NBS 1959]. Both of these documents 

were based on and consistent with similar guidance from International Commission on Radiological 

Protection (ICRP) Publication 2 [ICRP 1959]. After the publication of the NBS handbooks, DOE issued 

orders or regulations establishing air concentration limits applicable to its sites (for example, in AEC 

Manual Chapter 0524 [U.S. Atomic Energy Commission (AEC) 1968] and DOE Order 5480.11 [DOE 

1988]). In December 1993, DOE issued 10 Code of Federal Regulations (C.F.R.) Part 835 to establish 

limits on air concentrations to be effective no later than January 1, 1996 [DOE 1993]. This rule was 

updated in 2010. 10 C.F.R. 835, 2010. Table 2-1 lists the history of workplace air concentration limits 

applicable at DOE sites for a number of important particulate radionuclides. This is not meant to be 

exhaustive, nor does it imply that all of these nuclides would be present at all sites to which this TIB is 

applicable.

Most sites performed total alpha and total beta counting on air samples using either a time delay or 

mathematical correction to account for radon progeny. Radionuclide identification was either not 

performed or was performed occasionally as a check on basic assumptions from knowledge of the 

facility source terms and processes. Trigger levels and prompt decisions for changing access to an 

area, usually by placing a “respiratory protection required” restriction for the area, were usually based 

on total alpha or total beta air concentrations. Because the radionuclide was not identified for every 

sample, the limit for the most restrictive, plausible radionuclide was often used to establish the trigger

level. For facilities handling transuranic elements, the limiting air concentration for the alpha
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 8 of 32

Table 2-1. Limiting air concentrations for selected particulates from 1953 to present (μCi/mL).

a

Alpha emitters

Radionuclideb NBS 1953 NBS 1959

AEC Manual

Chapter 0524c

DOE Order

5480.11d

10 C.F.R.

Part 835 1993e

10 C.F.R. 

Part 835 2010f

Po-210 7E−11 2E−10 2E−10 3E−10 3E−10 2E−10

Th-230 Not listed 2E−12 2E−12 3E−12 3E−12 3E−12

Th-232 Not listed 2E−12g 3E−11h 5E−13 5E−13 3E−12

NU soluble 1.7E−11 7E−11 7E−11h Not listed Not listed Not listed

NU insoluble 1.7E−11 6E−11 6E−11h Not listed Not listed Not listed

U-234 soluble

(D)

Not listed 6E−10 6E−10 5E−10 5E−10 5E−10

U-234 

insoluble (Y)

Not listed 1E−10 1E−10 2E−11 2E−11 7E−11

U-238 soluble

(D)

Not listed 7E−11 7E−11 6E−10 6E−10 5E−10

U-238 

insoluble (Y)

Not listed 1E−10 1E−10 2E−11 2E−11 8E−11

Np-237 Not listed 4E−12 4E−12 2E−12 2E−12 8E−12

Pu-238 Not listed 2E−12 2E−12 3E−12 3E−12 6E−12

Pu-239 2E−12 2E−12 2E−12 2E−12 2E−12 5E−12

Am-241 3E−11 6E−12 6E−12 2E−12 2E−12 5E−12

Pu-242 Not listed 2E−12 2E−12 2E−12 2E−12 5E−12

Cm-244 Not listed 9E−12 9E−12 4E−12 4E−12 9E−12

Cf-252 Not listed 2E−11 6E−12 1E−11 1E−11 1E−11

Beta emitters

Radionuclideb NBS 1953 NBS 1959

AEC Manual

Chapter 0524c

DOE Order

5480.11d

10 C.F.R.

Part 835 1993e

10 C.F.R.

Part 835 2010f

Na-24 2E−8 2E−8 1E−7 2E−6 2E−6 4E−7

P-32 1E−7 7E−8 7E−8 2E−7 2E−7 1E−7

S-35 1E−6 3E−7 3E−7 9E−7 9E−7 5E−7

Sc-46 7E−8 2E−7 2E−8 1E−7 1E−7 1E−7

Cr-51 8E−6 1E−5 2E−6 8E−6 8E−6 1E−5

Mn-54 Not listed 4E−8 4E−8 3E−7 3E−7 4E−7

Co-58 Not listed 5E−8 5E−8 3E−7 3E−7 3E−7

Co-60 1E−6 9E−9 9E−9 1E−8 1E−8 3E−8

Fe-59 6E−7 5E−8 5E−9 1E−7 1E−7 1E−7

Ni-63 2E−8 4E−8 6E−8 7E−7 7E−7 1E−6

Zn-65 2E−6 6E−8 6E−8 1E−7 1E−7 2E−7

Sr-89 2E−8 3E−8 3E−8 6E−8 6E−8 1E−7

Sr-90 2E−10 3E−10 1E−9 2E−9 2E−9 7E−9

Y-91 4E−8 3E−8 3E−8 5E−8 5E−8 9E−8

Nb-95 4E−7 1E−7 1E−7 5E−7 5E−7 4E−7

Zr-95 Not listed 3E−8 3E−8 6E−8 6E−8 9E−8

Mo-99 2E−7 2E−7 2E−7 6E−7 6E−7 5E−7

Tc-99 Not listed 6E−8 6E−8 3E−7 3E−7 1E−7

Ru-103 Not listed 8E−8 8E−8 3E−7 3E−7 2E−7

Ru-106 3E−8 6E−9 8E−8 5E−9 5E−9 1E−8

Ag-110m Not listed 2E−7 1E−8 4E−8 4E−8 7E−8

Sn-113 6E−7 5E−8 5E−8 2E−7 2E−7 2E−7

Sb-125 Not listed 3E−8 3E−8 2E−7 2E−7 1E−7

Cs-134 Not listed 1E−8 1E−8 4E−8 4E−8 5E−8

Cs-137 2E−7 1E−8 1E−8 7E−8 7E−8 8E−8

Ba-140 6E−8 4E−8 4E−8 6E−7 6E−7 3E−7

La-140 6E−8 1E−7 1E−7 5E−7 5E−7 3E−7
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 9 of 32

Radionuclideb NBS 1953 NBS 1959

AEC Manual

Chapter 0524c

DOE Order

5480.11d

10 C.F.R.

Part 835 1993e

10 C.F.R.

Part 835 2010f

Ce-141 Not listed 2E−7 2E−7 3E−7 2E−7 1E−7

Ce-144 7E−9 6E−9 6E−9 6E−9 6E−9 1E−8

Pm-147 2E−7 1E−7 6E−8 6E−8 6E−8 1E−7

Eu-152 Not listed 3E−7 2E−8 1E−8 1E−8 2E−8

Eu-154 6E−9 4E−9 7E−9 8E−9 8E−9 1E−8

Eu-155 Not listed 7E−8 7E−8 4E−8 4E−8 7E−8

Tb-160 Not listed 3E−8 3E−8 1E−7 1E−7 1E−7

Hf-181 Not listed 7E−9 4E−8 7E−8 7E−8 1E−7

a. NU = natural uranium.

b. Most limiting form (e.g., soluble, insoluble, inhalation class D, W, Y) is listed, with the exception of uranium, for 

which the soluble form was based on chemical toxicity.

c. Source: AEC [1968].

d. Source: DOE [1988] effective January 1989.

e. Source: DOE [1993].

f. Source: 10 C.F.R. 835, 2010. 

g. Printed as 2E−12 μCi/mL, but a footnote stated that continued use of 3E−11 μCi/mL was recommended until 

further investigation.

h. Based on special definitions for the curie that added disintegrations from selected progeny.

measurements was based on plutonium; for facilities with potential exposure to fission or activation 

products, the limiting air concentration for beta measurements was based on 90Sr; at uranium 

facilities, the limits for uranium were generally used.

The validity of the assumption that worker intakes, except for accidental intakes, were controlled so 

that intakes at limiting air concentrations for a chronic period are reasonable median values is 

discussed in Attachment A. Attachment A compares worker bioassay results to the urinary excretion 

that would be predicted from an intake at the rates assumed in this TIB. 

3.0 APPLICABILITY, LIMITATIONS, AND ASSUMPTIONS

3.1 APPLICABILITY

This TIB applies to:

• Sites or facilities that sampled particulate air concentrations in areas of risk and controlled 

exposure to intakes according to the measured concentrations (or controlled air concentrations 

by limiting the inventory of radioactive material such that there was no risk of exceeding

regulatory limits). 

• Employment between 1953 and the present. If the limiting air concentrations for the site of 

exposure are documented for years before 1953, those concentrations are used with the 

methodology presented in Sections 4.0 and 6.0. Attachment B provides the justification for 

these values. These earlier years are listed as separate rows in Table 4-1.

• Claims for which it is likely that the covered employee had no significant intakes of particulate 

radioactive material. This is somewhat subjective but typically includes employees with no 

bioassay monitoring or with monitoring results that are less than the minimum detectable 

amount. Attachment C contains information to help with this determination. 

• Intakes of particulate radioactive material only.

• All organs for unmonitored workers.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 10 of 32

• All organs other than the respiratory tract for monitored workers. The respiratory tract includes 

extrathoracic regions 1 and 2 (ET1 and ET2), lungs, thoracic lymph nodes [LN(TH)], 

extrathoracic lymph nodes [LN(ET)], and bronchial region [ICRP 1994a]. 

3.2 LIMITATIONS

This TIB has the following limitations:

• It does not apply to Nevada Test Site outdoor exposures before 1963.

• It applies only to particulate radioactive material. These particulate intakes are in addition to 

any intakes of 3

H, radioiodines, 14C, or radon/thoron and their progeny, as applicable.

• Because the thyroid is particularly sensitive to intakes of radioiodine, this TIB alone may not 

provide an overestimate to the thyroid (regardless of monitoring) if the worker had a potential 

for exposure to radioiodines. Any potential for exposure to iodine must be assessed and 

added to the TIB value when the thyroid is the organ of concern. This includes missed dose.

• Intakes of particulate material with a documented particle-size distribution other than 5-μm 

activity median aerodynamic diameter (AMAD) must be checked to ensure that the dose to the 

organ of concern from this TIB is greater.

• If site-specific limiting air concentrations were greater than those listed in Section 3.3, those 

concentrations must be used with the methodology presented in Sections 4.0 and 6.0. If the 

site-specific concentration was applicable to airborne contamination for a given radionuclide 

only and exposure was limited to that radionuclide, the dose reconstructor can apply the intake 

to that radionuclide only. For instance, Mound and Los Alamos National Laboratory (LANL) 

had special limits for exposure to 210Po and LANL had special limits for general alpha and beta

emitters through 1966.

• It does not apply to respiratory tract cancers where bioassay has been performed because 

missed dose from the insoluble forms of some of the more difficult-to-detect radionuclides can 

be larger than the values calculated here. This includes CLL because several respiratory tract 

organs are included in its assessment.

3.3 ASSUMPTIONS

This TIB applies the following assumptions:

• All significant intake exposure was covered by an air sampling program, or the radiation 

protection program had a valid method to ensure that air concentrations did not exceed limits. 

For example, airborne contamination might have been controlled by controlling the inventory of 

radioactive material in an area and/or the physical form of the material.

• Chronic intakes were for 40 hours per week, or 2,000 hours per year, of particulate radioactive 

material with a 5-μm-AMAD particle-size distribution. A graded approach to this assumption is 

applied based on exposure potential; this is discussed further in Section 6.0. 

• The breathing rate was 9.6 m3

/workday [ICRP 1994a] or 1.2 m3/hr averaged over an 8-hour 

day.

• For sites or facilities with an exposure to alpha-emitting radionuclides that was principally 

transuranic elements, chronic exposure was at 2 × 10-12 μCi/mL through 2009 and 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 11 of 32

5 × 10-12 μCi/mL beginning in 2010. These values are based on 239Pu, which, as noted in 

Section 2.0, is the typical assumption when there is an unknown mixture of alpha emitters.

This is also more favorable to the claimant than the application of the 232Th limiting value

because it will result in a larger assumed intake and therefore a larger dose.

• For sites or facilities with an exposure to beta-emitting radionuclides, chronic exposure was at 

2 × 10-9 μCi/mL through 2009 and 7 × 10-9 μCi/mL beginning in 2010. These values are based 

on 90Sr, which, as noted in Section 2.0, is the typical assumption when there is an unknown 

mixture of beta emitters. The largest value prior to 2009 was selected for application to that 

period because it will result in a larger assumed intake and therefore a larger dose. Another 

increase in the air concentration limits occurred in 2010, well after the initial implementation of 

this TIB, so the larger value is applied from 2010 forward.

• For sites or facilities with an exposure principally to uranium, chronic exposure was at 

6 × 10-10 μCi/mL through 2009 and 5 × 10-10 μCi/mL beginning in 2010. 

• Measured air sample concentrations were not always representative of the air concentration 

breathed. However, when applied to the long-term, 40-hour-per-week, chronic-intake 

assumption, it is assumed that the air sampling program was sufficient to prevent long-term 

intakes from exceeding the limiting air concentrations. See Section 7.0 for additional

consideration of the possible nonrepresentativeness of air sampling. 

4.0 INHALATION INTAKE

4.1 INTAKE QUANTITY

Table 4-1 lists the limiting air concentrations and the associated daily intake rates. There are some 

sites where alternative values were in place, as well as a handful of sites that had well-documented 

limits prior to 1953. The rationale for these values is documented in Attachment B. The inhalation 

intake is determined by: 

Intake = air conc. × breathing rate × exposure period (4-1)

From Equation 4-1, intakes in pCi/yr can be determined by:

Intake (pCi/yr) = air conc. (μCi/mL) × 1.2 m3

/hr × 2,000 hr/yr × 106 mL/m3 × 106 pCi/μCi (4-2)

or

Intake (pCi/yr) = air conc. (μCi/mL) × 2.4 × 1015 (4-3) 

where the air concentration is obtained from Table 4-1 or from site-specific limiting air concentrations 

(in μCi/mL) when applicable. Selection of the air concentration values is described in Section 3.0. 

Table 4-1. Default limiting air concentrations.a

Air concentration

(μCi/mL)

Associated daily

Exposure type intake (pCi)

Alpha-emitting radionuclides except for uranium facilities, 1953–2009 

(includes Hanford from 1949)

2E−12 1.31E+1

Alpha-emitting radionuclides except for uranium facilities, 2010 to 

present

5E−12 3.29E+1

Beta-emitting radionuclides except for uranium facilities, 1953–2009

(includes Hanford from 1949)

2E−9 1.31E+4 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 12 of 32

Exposure type

Air concentration

(μCi/mL)

Associated daily

intake (pCi)

Beta-emitting radionuclides except for uranium facilities, 2010 to 

present

7E−9 4.60E+4

Uranium including recycled uranium, 1953–2009 (includes Hanford 

from 1949 and LANL from 1951)

6E−10 3.94E+3

Uranium including recycled uranium, 2010–present 5E−10 3.29E+3

ORNL alpha-emitting radionuclides except for uranium facilities, 1944–

1952

3E−11 1.97E+2

ORNL beta-emitting radionuclides, 1944–1952 1E−7 6.57E+5

Hanford alpha-emitting radionuclides except uranium facilities, 1946–

1948

4E−11 2.63E+2

Hanford beta-emitting radionuclides, 1946–1948 1E−8 6.57E+4

LANL alpha-emitting radionuclides except uranium facilities or Po-210 

facilities, 1948–1952

3.2E−11

2.10E+2

LANL alpha-emitting radionuclides except uranium facilities or Po-210 

facilities, 1953–1963

4E−12 2.63E+1

LANL beta-emitting radionuclides, 1948–1952 1E−7 6.57E+5

LANL beta-emitting radionuclides, 1953–1969 3E−9 1.97E+4

LANL uranium facilities, 1948–1950 1.8E−10 1.18E+3

LANL Po-210 only,b 1948–1953 (exposure ended in 1953) 6.3E−10 4.14E+3

Mound Po-210 only,c 1952–1971 (exposure ended in 1971) Not applicable 5.88E+3

Rocky Flats alpha-emitting radionuclides in Pu chemistry operations or 

default for the site, 1953–1994 (2E−12 μCi/mL was used in the metal 

operations)

4E−12 2.63E+1

a. ORNL = Oak Ridge National Laboratory. 

b. LANL had special air concentration limits for Po-210. The doses associated with this intake will be larger than for 

general alpha-emitting radionuclides at 13.2 pCi/d for years of exposure but will be less for years after exposure ends. 

The dose reconstructor will have to run both cases and determine which option gives the largest probability of causation.

c. The Mound Po-210 intake rate is based on special urinalysis limits rather than an air concentration limit. The doses 

associated with this intake will be larger than for general alpha-emitting radionuclides at 13.2 pCi/d for years of exposure 

but will be less for years after exposure ends. The dose reconstructor will have to run both cases and determine which 

option gives the largest probability of causation. 

From Equation 4-3, the intake per calendar day in pCi is: 

Intake (pCi/cal. d) = [air conc. (μCi/mL) × 2.4 × 1015]/365.25 d (4-4)

or

Intake (pCi/cal. d) = air conc. (μCi/mL) × 6.6 × 1012 (4-5) 

For most sites intakes will be assigned for alpha and beta intakes. Only the uranium intake should be 

assigned for facilities with exposure to only uranium (or natural thorium), with the exception of years 

when exposure was to recycled uranium. For recycled uranium, add the associated contaminant 

intakes as applicable to the site. 

4.2 CHOICE OF RADIONUCLIDE

Because total alpha and total beta activity were measured on the air filters, the measurements 

represented all the particulate activity being breathed (as opposed to bioassay measurements that 

usually measure only certain radionuclides so that unmeasured radionuclides have to be accounted 

for in addition to the measured radionuclides). To be most accurate, the fractions of the total activity 

(alpha or beta) would have to be assigned to each radionuclide in the mixture in the air breathed. 

Those fractions were generally not determined on a regular basis and would have varied among sites, 

facilities, processes, or even specific work tasks.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 13 of 32

Rather than estimating radionuclide fractions, this TIB overestimates the internal dose by assigning 

100% of the intake to the single radionuclide that produces the largest dose per unit intake to the 

organ of concern. In addition, organ dose depends on the absorption type of the radionuclides. The 

radionuclide and absorption type combination that produces this “largest dose” can differ by organ, 

time of exposure, and time after end of exposure. Because the annual organ dose is the dose of 

interest, and the annual dose varies from year to year for a given radionuclide, the largest dose 

contributor could change over the years. For example, for a 10-year chronic intake of beta emitters, 

134Cs type F delivers the largest dose to the urinary bladder during years 1 through 10. However, if the 

date of diagnosis is sometime after the intake period, the assumption of a 106Ru type F intake during 

the 10 years of exposure yields the largest dose for years 11 through 14, as does 90Sr type F for all 

subsequent years. Rather than determining which radionuclide and absorption type combination 

produces the largest dose, an additional claimant-favorable assumption was made. Each year 

between the start of exposure and date of diagnosis is evaluated individually and the largest dose is 

assigned. For the previous example, it would be assumed that the intake was comprised of 

100% type F 134Cs when assigning years 1 through 10. For years 11 through 14, it would be assumed 

that the intake had been entirely made up of type F 106Ru, and that it was 90Sr for years 15 through 65.

Table 4-2 lists the inventory of radionuclides and absorption types from which the combination 

producing the largest dose can be obtained. This is the default list at present.

Table 4-2. Inventory of radionuclides and absorption types.

a

Alpha choice

Radionuclide Type

Am-241 M

Cf-252 M

Cm-244 M

Np-237 M

Po-210 F, M

Pu-238 M, S, 

nonmonotonic

Pu-239 M, S, SS

Radionuclide Type

Pu-240 M, S

Pu-242 M, S

Ra-226 M

Th-228 M, S

Th-230 M, S

Th-232 M, S

U-234 F, M, S

Beta choice

Radionuclide Type

Ag-110 M, S

Ba-140 F

Ce-141 M, S

Ce-144 M, S

Co-58 M, S

Co-60 M, S

Cr-51 F, M, S

Cs-134 F

Cs-137 F

Eu-152 M

Eu-154 M

Eu-155 M

Fe-59 F, M

Hf-181 F, M

La-140 F, M

Mn-54 F, M

Mo-99 F, S

Na-24 F

Radionuclide Type

Nb-95 M, S

Ni-63 F, M

P-32 F, M

Pm-147 M, S

Ru-103 F, M, S

Ru-106 F, M, S

S-35 F, M

Sb-125 F, M

Sc-46 S

Sn-113 F, M

Sr-89 F

Sr-90 F

Tb-160 M

Tc-99 F, M

Y-91 M, S

Zn-65 S

Zr-95 F, M, S
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 14 of 32

Uranium choice

Radionuclide Type

Th-232 M, S

U-234/RU F, M, S

a. RU = recycled uranium (U-234 plus the 

contaminants applicable to the site). 

When site values are unknown, 

contaminant ratios from Site Profiles 

for Atomic Weapons Employees that 

Worked Uranium Metals [NIOSH 2011] 

should be applied.

NOTE 1: Actinium-227 is a progeny of 231Pa in the 235U decay chain. It was probably not present 

in significant quantities unless 231Pa or 227Ac was purposely concentrated; therefore, it was not 

included in the default list for the alpha choice. It should be added to the list if 231Pa or 227Ac 

was handled in a pure or concentrated form at the site in question.

NOTE 2: Thorium-232 is included in the uranium list because many uranium facilities also 

processed thorium at some time. Thorium-232 can be removed from the list if documentation 

clearly demonstrates that the facility did not handle thorium.

NOTE 3: For strontium, type S is applicable to the titanate form only and is unlikely to be 

present at most sites. Type S was not included in the default list for the beta choice. If it is 

established that a site had strontium titanate, type S strontium will have to be added to the list. 

Check the Site Profile for applicability. Adding type S strontium will significantly increase the 

dose for some organs.

NOTE 4: Nonmonotonic 238Pu is addressed in DCAS-RPT-005, Alternative Dissolution Models 

for Insoluble Pu-238 [NIOSH 2018]. Two models are described in the report. The appropriate 

model should be included for sites where pure 238Pu was present.

5.0 INGESTION INTAKE

The possibility of ingestion intakes must be considered separately from inhalation intakes when intake 

is not based on bioassay measurements. OCAS-TIB-009, Estimation of Ingestion Intakes, provides 

the method for estimating ingestion intakes based on air concentrations [NIOSH 2004]:

Ingestion intake = 0.021 × inhalation intake (5-1)

These intakes should be applied to the same years for which inhalation intakes occurred using the 

same radionuclide. Use the f1 associated with the absorption type from Annex F in ICRP 

Publication 68 [ICRP 1994b].

6.0 APPLICATION

The primary application of this TIB is as an overestimating efficiency method applied to monitored 

workers with few to no positive bioassay results. This can greatly reduce the assessment time. While 

applicable to unmonitored workers, co-exposure intakes take precedence when available.

Because of the complexity of this approach, a tool is required for its application. Values from this TIB 

have been incorporated into the Web CAD application. Direction on its use can be found with the Web 

CAD user guidance documents.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 15 of 32

As noted in the previous sections, there are three categories of radionuclides:

• Alpha-emitting.

• Beta-emitting.

• Uranium.

Multiple categories may be applicable to a site. Some large sites contained facilities that performed 

different functions. For example, the Hanford Site is a reactor site but also had fuel fabrication 

facilities. The fabrication facilities normally controlled air concentrations to uranium limits. Therefore, 

the uranium list should be applied to individuals working in those facilities.

Some sites operated with particular nuclides in campaigns. Once the campaign ended, the nuclide 

was no longer routinely handled. For example, the Fernald site produced thorium products during 

several campaigns but did not routinely handle it between these campaigns. Therefore, it is 

permissible to remove thorium from the list of possible radionuclides during times when the individual

was not exposed to thorium. This can be done in other situations when there is clear evidence that the 

individual was not exposed to a particular radionuclide.

6.1 CONSIDERATIONS

Both the worker’s exposure potential and employment period are considered when determining the 

intake rate to be applied. 

6.1.1 Exposure Potential

The dose reconstructor must apply judgment when determining the appropriate category for the 

exposure potential for individual workers and take into account all information in the worker’s file, 

(e.g., telephone interviews, work area). A worker’s assigned category can change over time if the 

worker changed job titles or work locations.

• Intermittent: Individuals with jobs that could have involved work with unsealed sources on

occasion but not routinely, or individuals who sometimes entered an area with a potential for

airborne activity levels greater than the environmental background.

• Routine: Individuals with jobs that were likely to have routinely involved work with unsealed

sources, or individuals who worked in areas likely to have airborne activity levels greater than

the environmental background.

Attachment C and OTIB-0014, Assignment of Environmental Internal Doses for Employees Not 

Exposed to Airborne Radionuclides in the Workplace, provide guidance on making this determination 

[ORAUT 2004]. 

6.1.2 Employment Period

With the implementation of DOE Order 5480.11, Radiation Protection For Occupational Workers, in 

1989 [DOE 1988] and the subsequent codification of requirements (10 CFR Part 835, Occupational 

Radiation Protection [DOE 1993]) a few years later, monitoring programs became more robust and 

personnel who had a modest exposure potential were likely to have been monitored. Respiratory 

protection was generally required for radiological areas that had levels greater than 10% of the 

derived air concentration on which this TIB is based. 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 16 of 32

6.2 INTAKE ASSIGNMENTS

6.2.1 Unmonitored Workers 

Intakes for unmonitored workers are divided into multiple categories as described below. Table 6-1 

summarizes this information. As noted above, co-exposure intakes take precedence when available. 

Table 6-1. Unmonitored workers. 

Exposure potential Period Application of dose

Intermittent Before 1989 50% of Table 4-1 intake rates

Intermittent 1989 and later 5% of Table 4-1 intake rates

Routine Before 1989 Table 4-1 intake rates

Routine 1989 and later 10% of Table 4-1 intake rates

6.2.1.1 Through 1988

Co-exposure intakes are the preferred assignment. If these are not available, this OTIB may be 

applied. For those workers who had a potential for routine exposure to airborne radioactivity, the 

Table 4-1 intake rates are applied. For those with an intermittent exposure potential, 50% of the Table 

4-1 values are applied. This is based on occupancy factor, which is assumed to be uniformly 

distributed from 0 to 1, resulting in the application of a mean value of 0.5. 

6.2.1.2 After 1988

As noted in Section 6.1.2, more stringent monitoring requirements were imposed in 1988. Based on 

this, 10% of the values described in Section 6.2.1 are applied beginning in 1989.

6.2.2 Monitored Workers

The full Table 4-1 intake rates may be applied to monitored workers when all of their results are less 

than the minimum detectable amount as an overestimate of the missed dose portion of the 

assessment. Any positive results or known incidents must be assessed separately and added to the 

doses resulting from the Table 4-1 intakes. 

6.3 USE DURING SPECIAL EXPOSURE COHORT PERIODS

This TIB can be applied to any claim during a Special Exposure Cohort (SEC) period that meets the 

criteria, subject to the additional SEC limitations. In the case of an SEC class where there are 

identified infeasibilities that limit the nuclides that can be assessed, the intake rates in Table 4-1 are

unaffected. The values are the gross airborne activities assumed to have been used for control during 

the operations. They can still be used to assign an upper bound to the nuclides that are not 

designated as infeasible. However, nuclides that have been designated as infeasible are to be 

removed from consideration. If an entire set of nuclides is deemed infeasible (e.g., alpha emitters or 

mixed fission products), then the corresponding category (alpha and beta, respectively) cannot be 

used because the infeasibility means it has been determined that an upper bound cannot be placed 

on the category.

6.4 SITES WITH URANIUM AND TRANSURANIC AREAS

At facilities where there are both uranium and transuranic areas, either the alpha or the uranium value

is assigned because they are each based on gross alpha measurements and a worker would not be 

exposed to both at the maximum permissible concentration for 2,000 hours in a year. The beta 

category is in addition to this and not addressed in this section.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 17 of 32

6.4.1 Monitored Workers

For those who worked in both transuranic and uranium areas, assign intakes based on the alpha 

values. If the worker has uranium bioassay, add uranium dose (missed or fitted as appropriate) to this 

value.

If monitored only for uranium and there is no evidence of work in nonuranium areas, apply uranium 

values or assess the uranium bioassay.

6.4.2 Unmonitored Workers

Co-exposure intakes are the preferred assignment. If these are not available, the Table 4-1 intakes 

may be applied. If the worker’s employment was entirely in a uranium area, assign the uranium intake 

values. If employment was in multiple areas, use the alpha values.

7.0 UNCERTAINTIES

Assuming an intake at the limiting air concentration for every minute of employment is probably an 

overestimate. However, there are sources of uncertainty. For instance: 

• The air sample results might not have been representative of the air breathed. If a worker was 

close to a localized source, the air concentration the worker breathed might have been higher 

than the air collected by a sampler several to tens of feet away. Breathing Zone to General 

Area Air Concentration Ratios in Small Workrooms [ORAUT 2021] discusses this issue in 

detail for certain conditions. Offsetting this problem somewhat is the likelihood that the worker 

breathed larger particles than the air sampler collected. The time spent near a localized source 

would have been less than full time.

• Enforcement of the limiting air concentrations at some facilities for some periods might have 

been lax.

• Workers may have worked overtime during some periods.

• Before widespread use of alarming continuous air monitors, exposure to air concentrations 

above limiting air concentrations for periods of days to a few weeks was possible. For 

instance, a filter exchanged weekly with delayed counting for radon decay could easily result 

in a 2-week lag between the change in air concentration and change in access control. Even 

with the use of continuous air monitors, radon progeny interference was a problem with alpha 

monitoring in many facilities so that immediate recognition of an air concentration slightly 

greater than the plutonium limit was difficult.

• For beta emitters, the counting efficiency for converting counts to total activity is dependent on 

the beta energy. If the beta energy of the radionuclide on the filter is less than the beta energy 

of the calibration source, the total activity would have been underestimated. This is offset 

somewhat by the generally lower dose per unit intake from the lower energy beta emitters. For 

alpha emitters, self-absorption of the alphas due to high dust loading might not have been 

compensated for.

• The volume of air sampled might not have been measured accurately; for instance, it was 

common to use flow rate meters and the average of the on/off flow rate to estimate the volume 

of air rather than using total air volume meters.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 18 of 32

• Operational logistics might have temporarily compromised the air sampling in some areas, 

such as pump failures, leaking filters, filters destroyed by harsh chemicals, or filters obviously 

contaminated by a source other than the air.

These problems arguably could have enabled intakes exceeding the air concentration limits for some 

periods. While it is unlikely that a worker was exposed at the limiting air concentrations for 2,000 

hours per year throughout their entire employment, because of the sensitivity to these uncertainties of 

the method used in this TIB to determine dose, the dose uncertainty distribution is lognormal with the 

geometric mean as determined by the equations in this document with a geometric standard deviation 

of 3.

Attachment A contains several comparisons with site data that demonstrate that this TIB provides 

overestimating intakes. Also, remember that exposure to tritium, radioiodines, radon/thoron, or 14C 

has to be accounted for separately from these intake/dose estimations.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 19 of 32

REFERENCES

10 C.F.R. 835, [2010]. Occupational radiation protection. [SRDB Ref ID: 165861]

AEC [1968]. Chapter 0524 Standards for radiation protection. AEC Manual, Chapter 0524. 

Washington, DC: U.S. Atomic Energy Commission. AEC 0524-01, November 8. [SRDB Ref ID: 

13037] 

Cantril ST [1945]. Tolerance limits. Letter to file. Hanford Engineer Works, Richland, WA. 7-2602, 

October 18. [SRDB Ref ID: 13428]

DOE [1988]. Radiation protection for occupational workers. Washington DC: U.S. Department of 

Energy. Order 5480.11, December 21. [SRDB Ref ID: 8073]

DOE [1993]. Federal Register Vol. 58 No. 238 December 14, 1993 Occupational Radiation Protection. 

Final rule. Fed Regist 58(238):65458. [SRDB Ref ID: 165855]

ICRP [1959]. ICRP 2 - Report of Committee II on permissible dose for internal radiation. ICRP 

Publication 2. London: Pergamon Press. [SRDB Ref ID: 11106]

ICRP [1994a]. ICRP 66 - Human respiratory tract model for radiological protection. ICRP 

Publication 66. Ann ICRP 24(1-3). [SRDB Ref ID: 22732]

ICRP [1994b]. ICRP 68 - Dose coefficients for intakes of radionuclides by workers. ICRP

Publication 68. Ann ICRP 24(4). [SRDB Ref ID: 22731]

LANL [1947]. Group CMR-12 monthly reports 1947. Los Alamos National Laboratory, Los Alamos, 

NM: University of California. [SRDB Ref ID: 27914]

LANL [1948]. Group CMR-12 monthly reports 1948. Los Alamos National Laboratory, Los Alamos, 

NM: University of California. [SRDB Ref ID: 27916]

LANL [1950]. Group CMR-12 monthly reports 1950. Los Alamos National Laboratory, Los Alamos, 

NM: University of California. [SRDB Ref ID: 27919]

LANL [1950–1952]. Group CMR-12 monthly reports 1950-1952. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 27920] 

LANL [1953–1954]. Group CMR-12 monthly reports 1953-1954. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 27921]

LANL [1961]. CMR building section annual report for 1961. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 47730]

LANL [1962]. CMR building section annual report for 1962. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 47733] 

LANL [1963]. CMR building section annual report for 1963. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 47734]

LANL [1964]. CMR building section annual report for 1964. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 69908] 
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LANL [1965]. CMR building section annual report for 1965. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 69909] 

LANL [1966]. CMR building section annual report for 1966. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 69912] 

LANL [1969]. CMR building section annual report for 1969. Los Alamos National Laboratory, Los 

Alamos, NM: University of California. [SRDB Ref ID: 47738]

NBS [1953]. NBS Handbook 52 - Maximum permissible amounts of radioisotopes in the human body 

and maximum permissible concentrations in air and water. Washington, DC: U.S. Department of 

Commerce, National Bureau of Standards. NBS Handbook 52, March 20. [SRDB Ref ID: 12332]

NBS [1959]. NBS Handbook 69 - Maximum permissible body burdens and maximum permissible 

concentrations in air and water for occupational exposure. Washington, DC: U.S. Department of 

Commerce, National Bureau of Standards. NBS Handbook 69, June 5. [SRDB Ref ID: 11110]

NIOSH [2002]. Internal dose reconstruction implementation guideline. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health. OCAS-IG-002 Rev. 0, August. [SRDB Ref ID: 22402] 

NIOSH [2004]. Estimation of ingestion intakes. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health. OCAS-TIB-009 Rev. 0, April 13. [SRDB Ref ID: 22397]

NIOSH [2011]. Site profiles for Atomic Weapons Employers that worked uranium metals. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 

National Institute for Occupational Safety and Health. Battelle-TBD-6000 Rev. 1, June 17. [SRDB Ref 

ID: 101251]

NIOSH [2018]. Alternative dissolution models for insoluble Pu-238. Cincinnati, OH: U.S. Department 

of Health and Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health. DCAS-RPT-005 Rev. 1, August 17. [SRDB Ref ID: 175415] 

ORAUT [2004]. Technical information bulletin – assignment of environmental internal doses for 

employees not exposed to airborne radionuclides in the workplace. Oak Ridge, TN: Oak Ridge 

Associated Universities Team. ORAUT-OTIB-0014 Rev. 00, June 22. [SRDB Ref ID: 19432]

ORAUT [2012]. Y-12 National Security Complex – occupational internal dose. Oak Ridge, TN: Oak 

Ridge Associated Universities Team. ORAUT-TKBS-0014-5 Rev. 03, March 12. [SRDB Ref ID:

109202] 

ORAUT [2013]. Los Alamos National Laboratory – occupational internal dose. Oak Ridge, TN: Oak 

Ridge Associated Universities Team. ORAUT-TKBS-0010-5 Rev. 02, April 18. [SRDB Ref ID: 124166]

ORAUT [2018]. Internal dose reconstruction. Oak Ridge, TN: Oak Ridge Associated Universities 

Team. ORAUT-OTIB-0060 Rev. 02, April 20. [SRDB Ref ID: 171554] 

ORAUT [2020a]. Roadmap to reconstructing dose. Oak Ridge, TN: Oak Ridge Associated 

Universities Team. ORAUT-PROC-0106 Rev. 02, October 1. [SRDB Ref ID: 183324] 
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ORAUT [2020b]. Internal dosimetry co-exposure data for the Savannah River Site. Oak Ridge, TN: 

Oak Ridge Associated Universities Team. ORAUT-OTIB-0081 Rev. 05, September 1. [SRDB Ref ID: 

178624] 

ORAUT [2020c]. Hanford site – occupational internal dose. Oak Ridge, TN: Oak Ridge Associated 

Universities Team. ORAUT-TKBS-0006-5 Rev. 07, September 1. [SRDB Ref ID: 178625] 

ORAUT [2021]. Breathing zone to general area air concentration ratios in small workrooms. Oak 

Ridge, TN: Oak Ridge Associated Universities Team. ORAUT-RPRT-0097 Rev. 00, March 29. [SRDB 

Ref ID: 185576] 

ORAUT [2022]. Support files for ORAUT-OTIB-0018, Rev. 02 zip file. Cincinnati, OH: Oak Ridge 

Associated Universities Team. [SRDB Ref ID: 192551]

Parker HM [1944a]. Product concentration in the air. Memo to I. Perlman. Oak Ridge, TN: Clinton 

Laboratories. ORNL CF 44-7-78, July 1. [SRDB Ref ID: 187999] 

Parker HM [1944b]. Review of air monitoring procedures at Clinton Laboratories. Oak Ridge, TN: 

Clinton Laboratories. CH-2562, September. [SRDB Ref ID: 13256]

Patterson CM [1949]. General operating tolerances. Letter to L.S. Taylor, National Bureau of

Standards. Hanford Works, Richland, WA. HW-12710, March 11. [SRDB Ref ID: 7756]
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 22 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Uranium ................................................................................................................................. 23

A.2 Plutonium............................................................................................................................... 24

A.3 Fission Products .................................................................................................................... 26

A.4 Conclusion ............................................................................................................................. 27

LIST OF FIGURES 

FIGURE TITLE PAGE

A-1 Comparison of Y-12 co-exposure and predicted OTIB-0018 type M uranium in urine 

values. ...................................................................................................................................23

A-2 Comparison of Y-12 co-exposure and predicted OTIB-0018 type S uranium in urine 

values. ...................................................................................................................................24

A-3 Comparison of SRS co-exposure and predicted OTIB-0018 types M and S plutonium in 

urine values............................................................................................................................25

A-4 Comparison of Hanford co-exposure and predicted OTIB-0018 types M and S plutonium 

in urine values........................................................................................................................26

A-5 Comparison of Hanford co-exposure and predicted OTIB-0018 type F 90Sr in urine 

values. ...................................................................................................................................27
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 23 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION (continued)

In this TIB it is presumed that weapons sites with a radiological control program limited exposures to 

airborne radioactive contaminants to less than applicable limits. These limits varied with time and 

isotope of concern, and it is acknowledged that exposures to concentrations greater than these limits 

did occur. However, it is assumed that, when integrated over time, the average exposure to any 

individual was less than that which would occur from continuous exposure at the limit. The validity of 

this assumption is confirmed in this attachment by comparing the projected excretion rates from longterm intakes at the levels given in Table 4-1 to the geometric mean urine sample values determined 

from several co-exposure studies. Documentation for generation of the figures below can be found in 

ORAUT [2022].

A.1 URANIUM

Uranium urinalysis data from the Y-12 site were used to assess the validity of the assumption. The 

Y-12 site processed uranium extensively. The data consisted of hundreds of urine samples each 

month from 1952 through 1985 [ORAUT 2012]. Figure A-1 plots these median sample results as well 

as the uranium result predicted by this TIB for an inhalation of type M uranium.

Figure A-1. Comparison of Y-12 co-exposure and predicted OTIB-0018 type M uranium in 

urine values. 

The TIB result is considerably higher than the actual Y-12 median urine sample result. The predicted 

excretion from a short-term intake of 2 years beginning 1 month after the start of a chronic intake is 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 24 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION (continued)

also shown because it takes time for the intake activity to reach the bladder and subsequently be 

excreted. It can be seen from the figure that the urine activity rapidly reaches equilibrium and is 

approximately 10 times higher than the highest actual mean result. This verifies that for Y-12 uranium 

intakes, either the assumed intake is an overestimate or the lung absorption of the uranium is

considerably slower than type M.

Figure A-2 shows the same information using an absorption type S assumption for the TIB values. 

This graph shows that for long-term exposure this TIB overestimates actual results even if absorption 

type S is assumed. The short-term exposure, on the other hand, indicates that it could take as long as 

3 years to reach the level of the highest median urinalysis result. This implies that this TIB approach 

might not be an overestimate for type S exposures lasting less than 3 years. The more soluble types 

(F and M) will provide the largest doses to the systemic organs but type S is limiting for the respiratory 

tract. Therefore, this TIB is not applicable to the respiratory tract.

Figure A-2. Comparison of Y-12 co-exposure and predicted OTIB-0018 type S uranium in

urine values.

A.2 PLUTONIUM

The Savannah River Site (SRS) worked extensively with plutonium. The geometric mean of the 

plutonium urine samples were evaluated from 1955 through 1990 [ORAUT 2020b]. 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 25 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION (continued)

The expected excretion rates from a chronic intake of types M and S 239Pu at the alpha-emitting 

radionuclides intake rate in Table 4-1 are plotted against the site co-exposure values in Figure 

A-3.The figure indicates that the TIB values would be likely to exceed the measured data soon after 

the start of a chronic type M inhalation. The type S inhalation, however, might not result in detectable 

urine samples.

Figure A-3. Comparison of SRS co-exposure and predicted OTIB-0018 types M and S

plutonium in urine values. 

The Hanford site produced much of the plutonium used by the weapons program. It appears to be 

reasonable, therefore, to review Hanford site plutonium urine results against the assumptions in this 

TIB.

The TIB analysis evaluated plutonium urine samples from Hanford from 1949 through 1988 [ORAUT 

2020c]. Figure A-4 shows the predicted excretion rates from this TIB for both a type S and a type M 

inhalation of 239Pu. As with the SRS data, the graph indicates that the TIB values would be likely to 

exceed the measured data soon after the start of a chronic type M inhalation, but a type S inhalation 

might not result in a detectable urine sample.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 26 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION (continued)

Figure A-4. Comparison of Hanford co-exposure and predicted OTIB-0018 types M and S 

plutonium in urine values. 

A.3 FISSION PRODUCTS

The fission product that was primarily sampled in urine at Hanford was 90Sr. Figure A-5 shows the 

urine result predicted from the values used in this TIB for a chronic inhalation of type F 90Sr assuming 

an intake at the beta-emitting radionuclide rate. The figure shows that the TIB predictions greatly 

exceed the site co-exposure GMs. 
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 27 of 32

ATTACHMENT A 

VALIDATION OF THE BASIC ASSUMPTION (continued)

Figure A-5. Comparison of Hanford co-exposure and predicted OTIB-0018 type F 90Sr in 

urine values. 

A.4 CONCLUSION

The analysis discussed above indicates that the assumption made in this TIB is valid if the material to 

which an individual is exposed has type F or type M absorption characteristics. Because these are the 

limiting absorption types for systemic organs, it appears the assumption is valid for systemic organs.

Type S, however, is the limiting absorption type (when comparing the same intake values for different 

absorption types) for the respiratory tract. Due to the detection limits of urinalysis, it cannot be shown

that the values of this TIB are an overestimate for the respiratory tract. Therefore, this TIB is not to be 

applied to cancers of the respiratory tract.
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 28 of 32

ATTACHMENT B 

AIR CONCENTRATION OR OTHER LIMITS BEFORE 1953

Air concentration limits established for a site before 1953 can be used to extend the applicability of 

this TIB to those earlier years. This attachment provides the justification for the values in Table 4-1 

that are prior to 1953.

Because Hanford Site tolerance levels were used to control intakes, they fit the criteria of air 

concentration limits. The alpha and beta particulate air concentration limits at Hanford from at least 

1949 to 1952 were 1 × 10-12 μCi/mL for alpha in nonuranium facilities, 1 × 10-9 μCi/mL for beta, and 

1.5 × 10-4 μg U/mL (which converts to 1.1 × 10-10 μCi/mL) for uranium facilities [Patterson 1949]. 

These concentrations are less than the concentrations listed in Table 4-1; thus, the use of Table 4-1 

values is a plausible overestimate. Therefore, this TIB approach can be used unmodified for Hanford 

claims from 1949 to the present. Higher tolerance levels of 1 × 10-8 μCi/mL for beta emitters and 

4 × 10-11 μCi/mL for plutonium were in place at least by October 1945 [Cantril 1945].

Oak Ridge National Laboratory (ORNL) used the concept of tolerance levels for air concentrations 

before 1953. By July 1944, ORNL had established an air concentration limit of 5 × 10-10 μg/mL 

(3 × 10-11 μCi/mL) for plutonium based on alpha counting [Parker 1944a]. A limit for beta emitters in air 

(based on tolerance in the thyroid for 131I even though they might not have been collecting iodine 

properly on their filters) was established at least by 1944 at 1 × 10-7 μCi/mL [Parker 1944b].

LANL also established tolerance levels for air concentrations for specific buildings as early as 1948. 

The tolerance levels varied by building, apparently based on the predominant radionuclide used in the 

building. For beta emitters the limit was stated as 1 × 10-7 μCi/mL in one reference [LANL 1948]. The 

air concentration limit for alpha emitters other than uranium or 210Po was 70 disintegrations per minute 

(dpm)/m3 (3.2 × 10-11 μCi/mL) for 1948 through 1952 [LANL 1947, 1950, 1950–1952]. This was 

actually the highest limit, and many buildings had lower limits. For uranium buildings the highest air 

concentration was 400 dpm/m3 (1.8 × 10-10 μCi/mL) reported in both late 1947 and 1950, so it was 

assumed to apply throughout the period 1948 to 1950 [LANL 1947, 1950]. For 210Po, which was a 

source of exposure at LANL only for 1948 to 1953 [ORAUT 2013], the air concentration limit was the 

same throughout the period at 1,400 dpm/m3 (6.3 × 10-10 μCi/mL) [LANL 1947, 1950, 1953–1954]. 

The concentration limits for alpha emitters and beta emitters changed in 1953. The highest air 

concentration limit for a plutonium facility was 9 dpm/m3 (4 × 10-12 μCi/mL) [LANL 1953–1954], which 

continued to show in reports in 1961 [LANL 1961] and 1963 [LANL 1963]. Reports from 1964 [LANL 

1964] show a drop to 4 dpm/m3

. The limiting air concentration for beta emitters found after 1953 

(referred to as fission products for the earlier years and gross beta thereafter) was listed at 6,700 

dpm/m3 (3 × 10-9 μCi/mL) in annual reports from 1961 through 1969 [LANL 1961, 1962, 1963, 1964, 

1965, 1966, 1969]. It was therefore assumed that this limit applied from 1953 to 1969. The limits for 

uranium in reports during and after 1951 [LANL 1950-1952, 1961, 1963, 1969] were less than the 

NCRP value in Table 4-2, so the NCRP value was assumed to apply. In other words no adjustment 

from the default value in Table 4-2 was needed.

The Rocky Flats site used two air concentration limits for plutonium operations throughout its 

operational period: 2 × 10-12 μCi/mL was used for plutonium metal operations and 4 × 10-12 μCi/mL 

was used for plutonium chemistry operations. These values were used through 1994 [ORAUT 2020b].
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 29 of 32

ATTACHMENT C 

EXPOSURE POTENTIALS

TABLE OF CONTENTS

SECTION TITLE PAGE

C.1 Job Categories....................................................................................................................... 30

C.2 Example Work Locations........................................................................................................ 31
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 30 of 32

ATTACHMENT C 

EXPOSURE POTENTIALS (continued)

C.1 JOB CATEGORIES

Likely Low Potential for Work with Unsealed Sources

Administrator

Assistant 

Business systems specialist

Cafeteria worker

Checker

Clerk

Computer specialist

Dispatcher

Draftsman

Groundskeeper

Instructor

Manager

Medical technician

Office supervisor

Planner

Quality assurance specialist

Program analyst

Programmer

Radio operator

Recruiter

Scheduler

Secretary

Telephone operator

Some Potential for Work with Unsealed Sources, Depending on Job Specifics

Biologist

Boilermaker

Bricklayer

Carpenter

Construction worker

Driver

Electrician

Electronics technician

Engineer

Equipment operator

Firefighter

Foreman

Foundry worker

Heavy equipment operator

Health physics analyst

Instrument mechanic

Insulator

Ironworker

Janitor

Laborer

Mechanic

Painter

Patrolman

Photographer

Scientist

Security guard

Specialist

Storekeeper

Supervisor

Surveyor

Technician

Likely High Potential for Work with Unsealed Sources

Analytical chemist

Assembly worker

Chemical operator

Fabricator

Glovebox worker

Health physics technician

Machinist

Material handler

Metallurgist

Millwright

Pipefitter

Plumber

Processor

Production worker

Radiation monitor

Radiochemist

Reactor operator

Steamfitter

Ventilation and balance operator

Waste handler

Welder
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 31 of 32

ATTACHMENT C

EXPOSURE POTENTIALS (continued)

C.2 EXAMPLE WORK LOCATIONS

High Potential for Airborne Activity (Alpha, Beta/Gamma, and/or Uranium)

• Uranium refining:

– Natural, depleted, and enriched uranium reactor fuel and targets: Feed Materials 

Production Center and Weldon Spring Site.

– Weapons parts and highly enriched reactor fuel: Oak Ridge National Laboratory.

– Production of UF6 feed: Oak Ridge, Paducah, and Portsmouth Gaseous Diffusion 

Plants.

• Fuel and target fabrication:

– Highly enriched uranium: SRS 300 M Area; Hanford 300 Area.

• Chemical separations:

– Weapons plutonium: Hanford 200 East and West Areas (PUREX [plutonium-uranium 

extraction], REDOX [reduction oxidation], T and B Plants, 231-Z Plant); SRS

(F Canyon complex).

– Uranium recycling: Hanford (UO3 Plant, U Plant); SRS (H Canyon complex); Idaho 

National Laboratory (Idaho Chemical Processing Plant).

• Weapons component fabrication:

– Plutonium: Rocky Flats Plant; Hanford 234-5 Plutonium Finishing Plant; Los Alamos 

National Laboratory (TA-21 and TA-55).

• Weapons component fabrication:

– Plutonium recycling: Rocky Flats; Hanford 234-5 Plutonium Finishing Plant; Los 

Alamos National Laboratory (TA-55).

– Highly enriched uranium; Y-12; Rocky Flats Plant.

• Isotope separation:

– Uranium: Oak Ridge, Paducah, and Portsmouth Gaseous Diffusion Plants.

• Reactor operations:

– Hanford (B, D, F, H, DR, C, KW, KE, and N Reactors); SRS (R, P, K, L, and 

C Reactors).
Document No. ORAUT-OTIB-0018 Revision No. 02 Effective Date: 07/01/2022 Page 32 of 32

ATTACHMENT C 

EXPOSURE POTENTIALS (continued)

• Weapons testing:

– Nevada Test Site; Pacific Proving Ground; Tonopah Test Range.

• Weapons research and development:

– Los Alamos National Laboratory; Lawrence Livermore National Laboratory; Sandia

National Laboratories (New Mexico and California).

• Uranium ore sampling:

– Feed Materials Production Center and Middlesex Sampling Plant.

• Other facilities with the potential for airborne uranium or plutonium.

Low Potential for Airborne Activity (Alpha, Beta/Gamma, and/or Uranium)

• Chemical separations:

– Tritium: SRS.

• Weapons component fabrication:

– Tritium including recovery and recycling: Mound Site, SRS (Tritium facilities).

– 6

Li deuteride including recovery and recycling: Y-12 Plant.

• Weapons operations:

– Assembly and dismantlement: Sandia National Laboratories (NM), Pantex Plant.

• Weapons operations:

– Modifications and maintenance: Pantex Plant, Sandia National Laboratories (NM),

Clarksville and Medina Modification Centers.

• Isotope separation:

– Lithium: Y-12 Plant COLEX [column exchange] and ELEX [electrical exchange] Plants.

– Heavy water: SRS Heavy Water Plant; Dana Heavy Water Plant.

• Fuel and target fabrication:

– Enriched lithium: Y-12 Plant, SRS M Area.

• Administrative, support, and other nonradiological facilities.