Page 1 of 18

DOE Review Release 08/28/2020

Estimating Doses for Plutonium Strongly 

Retained in the Lung

ORAUT-OTIB-0049 Rev. 02

Effective Date: 09/01/2020

Supersedes: Revision 01 PC-2

Subject Expert(s): Thomas R. LaBone and David Allen, NIOSH Dose Reconstruction Team Leader

Document Owner 

Approval: Signature on File

Elizabeth M. Brackett, Document Owner

Approval Date: 08/07/2020

Concurrence: Signature on File

Matthew C. McFee, Deputy Project Director

Concurrence Date: 08/11/2020

Concurrence: Vickie S. Short Signature on File for

Kate Kimpan, Project Director

Concurrence Date: 08/10/2020

Approval: Signature on File

Timothy D. Taulbee, Associate Director for Science

Approval Date: 08/12/2020

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-0049 Revision No. 02 Effective Date: 09/01/2020 Page 2 of 18

 

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

02/06/2007 00 Approved new technical information bulletin to provide information for 

a model for estimating doses for highly insoluble plutonium. 

Incorporates internal and NIOSH formal review comments. 

Incorporates Attributions and Annotations section. There is an 

increase in assigned dose and a PER is required. Training required: 

As determined by the Task Manager. Initiated by Donald E. Bihl.

12/18/2007 01 Approved revision which incorporates guidance on the application of 

super S adjustment factors to coworker-derived intakes. No further 

changes occurred as a result of formal internal review. Incorporates 

NIOSH formal review comments. Training required: As determined 

by the Task Manager. Initiated by Elizabeth M. Brackett.

09/26/2008 01 PC-1 Approved page change revision to add fecal sample information in 

Section 4.1.4 on page 16 and Attachment E on pages 58-60. 

Updates NIOSH required language on page 8 in Section 1.0. 

Corrected acronym on page 21 in Section 6.0. No sections were 

deleted. No further changes occurred as a result of formal internal 

and NIOSH review. Training required: As determined by the Task 

Manager. Initiated by Elizabeth M. Brackett.

11/29/2010 01 PC-2 Page change revision to correct errors in Table 4-7 on page 16 in 

Section 4.1 and associated text. Revises labels for Figures C-1, C-2 

and C-3 on pages 42 and 43 in Attachment C. No sections were 

deleted. No changes occurred as a result of formal internal and 

NIOSH review. Training required: As determined by the Objective 

Manager. Initiated by Elizabeth M. Brackett.

09/01/2020 02 Revision initiated to specify the new model to be used for 

reconstructing intakes and doses of type super S plutonium. This 

model consists of the International Commission on Radiological 

Protection Publication 130 human respiratory tract model coupled 

with the Publication 67 systemic model. Incorporates formal internal 

and NIOSH review comments. Constitutes a total rewrite of the 

document. Training required: As determined by the Objective 

Manager. Initiated by Elizabeth M. Brackett.
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 3 of 18

 

TABLE OF CONTENTS

SECTION TITLE PAGE

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

1.0 Introduction .............................................................................................................................. 5

2.0 Purpose ................................................................................................................................... 5

3.0 Background.............................................................................................................................. 5

4.0 Technical Basis........................................................................................................................ 6

4.1 Biokinetic Model ........................................................................................................... 6

4.2 Dosimetric Model.......................................................................................................... 7

5.0 Applications and Limitations..................................................................................................... 8

6.0 Attributions and Annotations .................................................................................................... 8

References ........................................................................................................................................ 10

ATTACHMENT A DETERMINATION OF SOLUBILITY PARAMETERS FOR SUPER S 

MODEL...........................................................................................................12

LIST OF TABLES

TABLE TITLE PAGE

A-1 241Am intakes calculated from lung counts using different Ss absorption parameters.............. 14

A-2 241Am intakes calculated from lung counts using different Fr and Sr absorption 

parameters.............................................................................................................................15

A-3 239Pu intakes calculated from urine data using different Fr and Sr absorption parameters....... 16

A-4 239Pu intakes calculated from urine data using different Fr absorption parameters.................. 16

LIST OF FIGURES

FIGURE TITLE PAGE

A-1 HAN-1 241Am lung data with calculated lung content using Publication 66 default 

absorption and Ss value of 1 × 10-6......................................................................................... 15

A-2 HAN-1 239Pu urine data with calculated urine content using type SS parameters ................... 17

A-3 HAN-1 241Am lung data with calculated lung content using type SS parameters..................... 18
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 4 of 18

ACRONYMS AND ABBREVIATIONS

AF absorbed fraction

AI alveolar-interstitial

ALV alveolar

Bq becquerel

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

GI gastrointestinal

HRTM human respiratory tract model

ICRP International Commission on Radiological Protection

INT interstitial

M moderate (absorption type)

NIOSH National Institute for Occupational Safety and Health

PER program evaluation report

ORAU Oak Ridge Associated Universities

RFP Rocky Flats Plant

SEE specific effective energy

SRDB Ref ID Site Research Database Reference Identification (number)

S slow (absorption type)

SS super S (absorption type)

TIB technical information bulletin

U.S.C. United States Code

§ section or sections

μm micrometer
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 5 of 18

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). TIBs may be used to assist NIOSH staff in the completion of 

individual dose reconstructions.

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 of 2000 [42 U.S.C. § 7384l(5) and (12)].

2.0 PURPOSE

The purpose of this document is to specify a biokinetic model that is used to evaluate the deposition, 

retention, and removal of inhaled very insoluble (type SS) plutonium particulates from the respiratory 

tract. This model merges the latest International Commission on Radiological Protection (ICRP) 

Publication 130 human respiratory tract model (HRTM) with the current Publication 67 plutonium 

systemic model and Publication 30 gastrointestinal (GI) tract model.

3.0 BACKGROUND

A body of evidence from animal studies and accidental human intakes has come forth in the last 

40 years indicating that inhaled plutonium oxides can be retained in the lung for a very long time. In 

recognition of this, in 1994 the ICRP increased the retention time of insoluble (type S) plutonium in the 

Publication 66 HRTM in relation to the retention predicted by the Publication 30 respiratory tract 

model (ICRP 1979, 1994, 1997). Nevertheless, a handful of accidental intakes of plutonium oxides at 

the DOE Rocky Flats Plant (RFP) (Mann and Kirchner 1967), Hanford Site (Carbaugh, Bihl, and Sula

1991; Carbaugh and LaBone 2003; Bihl et al. 1988), Los Alamos National Laboratory (Filipy 2004;

James 2005), and Savannah River Site (Carbaugh and LaBone 2003) have exhibited long-term 

retention of plutonium in the lung exceeding that predicted by the standard type S model. Recent 

autopsies on workers exposed to plutonium at the Mayak Production Association (Mayak) in Russia 

revealed a similar effect. Because these cases were from occupational human intakes rather than 

controlled animal experiments, information needed to define the circumstances that lead to retention 

of plutonium in the lung exceeding the type S model was insufficient [1]. Indeed, the scientific 

community lacked consensus about whether this phenomenon truly represented another type of 

material with different lung absorption parameters, a degradation of the anatomical or physiological 

processes that remove particles from the lung because of damage from smoking or other toxic 

materials or from the plutonium alpha radiation itself, or was a demonstration of extreme but natural 

individual human variability in these processes in a few workers [2]. However, it is clear that, with the 

depletion of the fast-removal components, the rate of removal of plutonium from the lung was slower 

than that predicted by type S material for some people under some conditions; as a consequence, the 

total dose to an organ accumulated over many years is greater. This phenomenon has been 

popularly referred to as “type super S (SS)”, although it is not established that it necessarily is caused 

only by slower absorption of the plutonium into the blood (Carbaugh and LaBone 2003). Publication 

66 does allow for the development of material-specific absorption parameters if sufficient information 

exists. While the absorption parameters in Publication 66 are controlled by chemical solubility and are 

thus dependent on chemical form, mechanical clearance from the lungs is considered to be 

independent of chemical form. In the course of evaluating design cases, it was observed that even 

when the absorption parameters were set to very long clearance times, the mechanical clearance 
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 6 of 18

 

from the lungs alone was too fast to account for the slow lung clearance observed in the design 

cases.

To address the problem of evaluating intakes of type SS plutonium, correction factors were published 

in Revision 00 of this document (ORAUT 2007). These factors were developed using nine cases from 

RFP and one case from Hanford that had well-defined intakes and exhibited long lung retention times. 

Individual lung clearance parameters, as well as absorption parameters, were modified for each case 

in order to match lung counts and urinalyses performed on these individuals. These individual 

adjustments in themselves were not considered to be appropriate (either as averages or as a 

distribution of ranges) for application to the general population. By choosing the worst-case 

clearances (i.e., the ones with the largest deviation from type S), a bounding absorption type was 

defined, which was applied to all cases where the default inhalation exposure is to type SS plutonium.

The original version of the TIB did not propose a new class of material for general modeling purposes 

or propose a new variation of the lung model. Rather, to account for the increased organ doses, the 

TIB analysis developed empirical “dose adjustment factors” from selected cases from RFP and 

Hanford that exhibited type SS behavior following intakes of 239Pu mixtures. For intakes calculated 

from urinary excretion data, a bounding analysis was implemented as an intake adjustment factor 

rather than a defined change in ICRP model parameters. This allowed intakes of type SS plutonium 

to be satisfactorily modeled, but the result was a complex method that has proved sometimes difficult 

to apply in practice.

The ICRP published a new lung model as part of Publication 130. The new model is a modification to 

the Publication 66 model. The modification slows down the mechanical clearance rate enough that 

absorption parameters can be developed to account for type SS material. The Publication 130 lung 

model is intended to be coupled to new biokinetic models that have not yet been published. However,

because the lung model is coupled in the same manner (absorption to the blood and removal to the 

GI tract), it is possible to couple the new lung model to the current GI tract and biokinetic models. 

Also necessary to allow this coupling to occur is the fact that the Publications 130 and 66 lung models 

describe the same physical regions of the lung allowing the current specific effective energy (SEE) 

values to be used. The one aspect still missing for NIOSH application to insoluble plutonium is the 

absorption parameters for the type SS material. Both models allow for development of parameters for 

specific material in cases where there is enough bioassay data to justify modifying parameters from 

the default values. Type SS plutonium parameters are developed and verified in Attachment A of this 

document.

Because the ICRP never intended these models to be assembled in this manner, the use of this 

hybrid model should be limited. This document describes the use of this model for type SS plutonium 

intakes only. The use of this model for any other material types is beyond the scope of this document.

4.0 TECHNICAL BASIS

4.1 BIOKINETIC MODEL

ICRP issued a revised HRTM in Publication 130, Occupational Intakes of Radionuclides: Part 1 (ICRP

2015), which is at present one of the newer ICRP models that is intended to replace the current 

models from the 1990s. More importantly, ICRP specifically designed Publication 130 to model the 

biokinetics of type SS materials in the respiratory tract.1

 This provides the opportunity to create a fully 

specified biokinetic model for type SS plutonium by coupling the Publication 130 HRTM with the 

existing plutonium systemic model in Publication 67, Age-Dependent Doses to Members of the Public 

from Intake of Radionuclides: Part 2 Ingestion Dose Coefficients (ICRP 1994b), along with the 

 

1 In fact, ICRP Publication 130 references ORAUT-OTIB-0049, Rev 00.
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 7 of 18

Publication 30 GI tract model in Publication 30, Limits for the Intake of Radionuclides by Workers, 

Part 1 (ICRP 1979). This “hybrid” model can be used to evaluate intakes calculated from air 

monitoring data, chest counts, urine bioassay, and fecal bioassay following intakes of type SS 

plutonium without the use of complex correction factors while at the same time using only official 

ICRP models.

The Publication 130 lung model is a fairly minor modification of the Publication 66 lung model:

• The alveolar-interstitial (AI) source region in the Publication 66 model consists of three source

compartments (AI1, AI2, and AI3). This region was replaced with two compartments (alveolar

[ALV] and interstitial [INT]) in Publication 130. The BB and bb regions in the Publication 66

model each have three compartments (BB1, BB2, and BBseq) while the BB2 and bb2

compartments are eliminated in the Publication 130 model. For details see Publication 130

Figure A-2.

• The deposition fractions for these compartments are those for 5-μm aerodynamic median

activity diameter aerosol inhaled by Reference Worker in Publication 130 Table A-2(c).

• The regional deposition fractions are given in Publication 130 Table A-1(b).

• The mechanical transfer rate constants are given in Publication 130 Table A-1(a).

Publication 66 provided default dissolution parameters for all elements. Publication 130 provides 

element-specific dissolution parameters that have not yet been published. The hybrid model uses the 

modified2 dissolution parameters given below that lower the predicted urinary excretion per unit intake 

to better match urinary observed excretion in workers (see Attachment A in this document) who have 

had intakes of type SS plutonium:

• Ss = 1 × 10-6

• Sr = 100.1

• Fr = 0.001209

The Publication 67 plutonium systemic model couples to the Publication 130 HRTM at the blood 

compartment. The structure and transfer rate constants are given in Table B-2 of Publication 67. The 

Publication 30 GI tract model couples to the systemic model and the HRTM. The transfer rate 

constants for the compartments of the GI tract are given in Figure 6.1 of Publication 30. The fraction 

of ingested type SS plutonium that transfers across the small intestine wall is the ICRP type S 

standard f1 = 1 × 10-5. 

4.2 DOSIMETRIC MODEL

The ICRP system of internal dosimetry uses SEEs to convert decays in a source region to dose in a 

target region. These SEEs exist as source and target pairs. The SEEs calculations include 

conversion factors as well as energy, yield, and radiation weighting factor of the emitted radiation. It 

also includes an absorbed fraction (AF) and the mass of the target tissue (Mt). The AF is simply the 

fraction of energy emitted by the source compartment that is absorbed in the target tissue.

Under Publication 66, the AI1, AI2, and AI3 compartments are three mathematical clearance rates 

from the same physical source region. As such, only one AF exists for the AI as a source region and 

the decays calculated in the three regions are included in that single source region. While 

Publication 130 does not seem to explicitly state it, it is clear that the ALV and INT compartments are 

2 Ss, and Fr are the only parameters in the hybrid model that are modified from the ICRP default values. 
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 8 of 18

 

also just two mathematical clearance rates from the same physical source region. This is clear in

Table A.2 of Publication 133 (ICRP 2016), which lists only AI as a source region. Therefore, the 

existing AF for the AI region can be applied to the sum of the decays in the ALV and INT 

compartments.

Publication 66 provided for different thicknesses for the source regions BB1 and BB2 (as well as bb1 

and bb2). Because of that, the AFs for these two sources are different. Publication 130 combined 

these two compartments into a single BB and single bb compartment; paragraph 135 describes the 

combined region as having a “thickness-weighted sum” of the two Publication 66 regions. 

Publication 133 describes this thickness-weighting as 5/11 and 6/11 for BB1 and BB2 and 2/6 and 4/6 

for bb1 and bb2, respectively. A mathematical formula is provided that indicates the weighting can 

simply be applied to the AFs for BB1 and BB2 to produce a new BB AF. Likewise, a similar formula is 

shown for bb1 and bb2. The dose reconstruction type SS model will use this weighting because it is 

discussed in Publication 130.

One last change ICRP made in Publication 130 was to the lung model in the calculated regional 

equivalent doses. Publication 66 calculates a dose to the “lung” region using a weighted average of 

the thoracic lung regions [BB, bb, AI, and LN(th)]. The revised ICRP system includes a change to the 

source and target regions of the body, which would now include a lymphatic system dose. Because 

of this, dose to the LN(th) was to be removed from the “lung” region dose weighting. Because ICRP 

has not yet published all parts of its new system, the system cannot yet be used in its entirety and no 

such lymphatic system dose will be calculated for EEOICPA at this time. Therefore, the original 

Publication 66 tissue weighting for calculating “lung” dose will continue to be used. 

In summary, except as noted above, all the currently used source-target pair AFs (and therefore the

SEEs) for the Publication 60 series models can be used for this new type SS model. Decays in the 

ALV and INT compartments will be assigned to the AI source region. The AF for the BB and bb 

regions will be a weighted average of the BB1 and BB2 AFs and a weighted average of the bb1 and 

bb2 AFs, respectively.

5.0 APPLICATIONS AND LIMITATIONS

The type SS model applies only to intakes of plutonium oxide and cermets produced with plutonium 

oxide as the ceramic material; however, it is favorable to the claimant to apply it if the intake material 

is unknown and plutonium oxide is a possibility. Considering the uncertainty in the nature of the 

material, long-term (years) air oxidation of formerly type M plutonium can be considered to apply.

Type SS applies only to intakes of plutonium for which the activity isotopic ratio of 239+240Pu to 238Pu is 

greater than 1. This restriction is based on the observed behavior of relatively pure 238Pu, which tends 

to be more soluble than 239Pu (Guilmette 1994; Hickman 1995; James et al. 2003). When this 

condition is met, type SS behavior applies to all isotopes in the plutonium mixture.

Type SS applies to the dose from 241Am in the mixture when the activity ratio of 239+240Pu to 241Am is 

greater than 1.

Type SS does not apply to situations where the plutonium is a minor constituent by mass in another 

matrix, such as in recycled uranium.

6.0 ATTRIBUTIONS AND ANNOTATIONS

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

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

These callouts are listed here in the Attributions and Annotations section, with information to identify 
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 9 of 18

 

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

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

for review on the Project’s Site Research Database.

[1] LaBone, Thomas R. ORAU Team. Deputy Principal Internal Dosimetrist. January 2007.

There are documented cases (see references in first paragraph of Section 3.0) of occupational 

exposure to plutonium where the plutonium is retained in the lung for longer periods of time 

than expected for type S plutonium.

[2] Bihl, Donald E. ORAU Team. Principal Health Physicist. January 2007.

Based on personal discussions on this topic with A. C. James, R. J. Guilmette, F. F. Hahn, W. 

J. Bair, and others. Also based on peer review on an article on this subject submitted to 

Health Physics that was rejected because of lack of consensus among the reviewers and

authors on key issues of the model.
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 10 of 18

 

REFERENCES

Bihl, D. E., T. P. Lynch, E. H. Carbaugh, and M. J. Sula, 1988, Methods to Improve Intake Monitoring 

for Freshly Separated, Poorly Transported Plutonium, PNL-6695, Pacific Northwest National 

Laboratory, Battelle Memorial Institute, Richland, Washington, September. [SRDB Ref ID: 

46752]

Carbaugh, E. H., D. E. Bihl, and M. J. Sula, 1991, “Long-Term Follow-Up of HAN-1, an Acute 

Plutonium Oxide Inhalation Case,” Radiation Protection Dosimetry, volume 38, numbers 1–3, 

pp. 99–104. [SRDB Ref ID: 18052]

Carbaugh, E. H., and T. R. LaBone, 2003, “Two Case Studies of Highly Insoluble Plutonium Inhalation 

with Implications for Bioassay,” Radiation Protection Dosimetry, volume 105, numbers 1–4, pp. 

133–138. [SRDB Ref ID: 18053]

Filipy, R. E., 2004, “Applying the International Commission on Radiological Protection (ICRP) 

Biokinetic Models,” p. 37 in Annual Report of the U. S. Transuranium and Uranium Registries, 

Annual Report Feburay 1, 2003 - January 31, 2004, USTUR-0197-04, S. M. Ehrhart and R. E. 

Filipy, editors, Washington State University, Richland, Washington. [SRDB Ref ID: 18054]

Guilmette, R. A., W. C. Griffith, and A. W. Hickman, 1994, “Intake Assessment for Workers Who Have 

Inhaled Pu-238 Aerosols,” Radiation Protection Dosimetry, volume 53, numbers 1-4, pp 127-

131. [SRDB Ref ID: 120904]

Hickman, A. W., W. C. Griffin, G. S. Roessler, and R. A. Guilmette, 1995, “Application of a Canine Pu238 Biokinetics/Dosimetry Model to Human Bioassay Data,” Health Physics, volume 68, 

number 3, pp 359-370. [SRDB Ref ID: 167452]

ICRP (International Commission on Radiological Protection), 1979, Limits for the Intake of 

Radionuclides by Workers, Part 1, Publication 30, Part 1, Pergamon Press, Oxford, England. 

[SRDB Ref ID: 22733]

ICRP (International Commission on Radiological Protection), 1994a, Human Respiratory Tract Model 

for Radiological Protection, Publication 66, Pergamon Elsevier Science Inc., Tarrytown, New 

York. [SRDB Ref ID: 22732]

ICRP (International Commission for Radiological Protection), 1994b, Age-Dependent Doses to 

Members of the Public from Intake of Radionuclides: Part 2 Ingestion Dose Coefficients, 

Publication 67, Pergamon Press, Oxford, England. [SRDB Ref ID: 36901]

ICRP (International Commission on Radiological Protection), 2015, Occupational Intakes of 

Radionuclides: Part 1, Publication 130, Sage Publishing, London, England. [SRDB Ref ID: 

168251]

ICRP (International Commission on Radiological Protection), 2016, The ICRP Computational 

Framework for Internal Dose Assessment for Reference Adults: Specific Absorbed Fractions, 

Publication 133, Annals of the ICRP, 45, pp. 1–74, Sage Publishing, London, England. [SRDB 

Ref ID: 168385]

James, A. C., 2005, “Progress on Modeling Whole-Body Cases,” Appendix C in Proposal to Manage 

and Operate the United States Transuranium and Uranium Registries, Washington State 

University, Richland, Washington, February 8. [SRDB Ref ID: 18055]
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 11 of 18

 

James, A. C., R. E. Filipy, J. J. Russell, and J. F. McInroy, 2003, “USTUR Case 0259 Whole Body 

Donation: A Comprehensive Test of the Current ICRP Models for the Behavior of Inhaled Pu238 Oxide Ceramic Particles,” Health Physics, volume 84, number 1, pp. 2–33. [SRDB Ref ID: 

77731]

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

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

7974]

ORAUT (Oak Ridge Associated Universities Team), 2007, Estimating Doses for Plutonium Strongly 

Retained in the Lung, ORAUT-OTIB-0049, Rev. 00, Cincinnati, Ohio, February 6. [SRDB Ref 

ID: 29975]
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ATTACHMENT A 

DETERMINATION OF SOLUBILITY PARAMETERS FOR SUPER S MODEL

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Isotopic Ratio ......................................................................................................................... 13

A.2 Data ....................................................................................................................................... 13

A.3 Long-Term Absorption Parameter.......................................................................................... 14

A.4 Short-Term Absorption Parameters........................................................................................ 15

A.5 Verification of Type SS Model Parameters............................................................................. 16

A.6 A Note on Chelation Therapy ................................................................................................. 17

LIST OF TABLES

TABLE TITLE PAGE

A-1 241Am intakes calculated from lung counts using different Ss absorption parameters.............. 14

A-2 241Am intakes calculated from lung counts using different Fr and Sr absorption 

parameters.............................................................................................................................15

A-3 239Pu intakes calculated from urine data using different Fr and Sr absorption parameters....... 16

A-4 239Pu intakes calculated from urine data using different Fr absorption parameters.................. 16

LIST OF FIGURES

FIGURE TITLE PAGE

A-1 HAN-1 241Am lung data with calculated lung content using Publication 66 default 

absorption and Ss value of 1 × 10-6......................................................................................... 15

A-2 HAN-1 239Pu urine data with calculated urine content using type SS parameters ................... 17

A-3 HAN-1 241Am lung data with calculated lung content using type SS parameters..................... 18
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 13 of 18

ATTACHMENT A

DETERMINATION OF SOLUBILITY PARAMETERS FOR SUPER S MODEL (continued)

While ICRP has published a new lung model, it has not published solubility parameters for plutonium. 

Therefore, solubility parameters are evaluated here for use with the type SS model. The original 

version of this TIB evaluated selected cases from RFP and Hanford that exhibited type SS behavior. 

A combination of one RFP case (RFP 872) and one Hanford case (HAN-1) resulted in worst-case 

correction factors at various times after an intake. However, in developing parameters for an actual 

model, it is not possible to use two different cases as one.

Plutonium intakes normally include several isotopes of plutonium as well as 241Am ingrowth from 241Pu 

decay. Lung counts performed for monitoring of plutonium intakes normally measure 241Am content in 

the lungs, while urinalysis normally measures 239Pu with or without some other additional isotopes of 

plutonium. As a result, it is critical to know the isotopic mix of the inhaled material in order to develop 

parameters that will describe the same intake using either type of bioassay. The HAN-1 case 

included an isotopic analysis of the inhaled material as well as a discussion of which isotopes of 

plutonium were measured in the urinalysis. Also, in the original version of this TIB, the HAN-1 case 

produced the worst-case correction factors for most years. Therefore, the HAN-1 case was used to 

develop the solubility parameters for type SS plutonium.

The solubility parameters considered are Fr, Sr, and Ss. The parameter Fr represents the fraction of 

the inhaled material that is absorbed by the blood relatively rapidly. Sr represents that rate at which 

the material is absorbed. The remaining fraction of the material (1 − Fr) is absorbed as a slower rate 

represented by Ss.

A.1 ISOTOPIC RATIO

Carbaugh and LaBone (2003) provides the isotopic ratio of the plutonium isotopes and 241Am in the 

material involved in the incident. The values are given in atomic percentages, but they easily convert 

to activity fractions. From this data, the two activity ratios important to this analysis can be calculated 

to be 168:1 for 241Pu-to241Am activity and 6.21:1 for 239Pu-to241Am activity. These ratios are 

important for two reasons. First, the lung counts for plutonium rely on 241Am counting. However, the 

241Am will include not only the inhaled 241Am but also 241Am from the decay of 241Pu in the body. 

Therefore, the 241Pu-to241Am activity ratio is necessary to account for this ingrowth of 241Am. Second, 

the 239Pu-to241Am ratio is important because, while lung counting relies on 241Am, urine samples 

would normally be analyzed for 239Pu. The 239Pu-to241Am ratio is necessary for comparison of lung 

counting data and urine data.

A.2 DATA

The lung count data consisted of 241Am measurements and were used directly. The urine data were 

analyzed using autoradiography procedures before 1983. Starting in 1983, alpha spectrometry was 

used. The autoradiography procedure would have detected 238Pu, 239Pu, and 240Pu together. The 

alpha counting would have distinguished between 238Pu and the other two but not between the 239Pu

and 240Pu. Therefore, the urine samples Carbaugh and LaBone (2003) described represent 238Pu + 

239Pu + 240Pu until 1983 and 239Pu + 240Pu starting in 1983. Based on the activity fractions of the 

inhaled material, the fraction of activity in the urine samples representing 239Pu is 0.588 before 1983 

and 0.669 starting in 1983.

From the urine samples in Carbaugh and LaBone (2003) and the activity ratios of the inhaled material, 

the amount of 239Pu excreted in the urine was calculated on each sample day. No adjustments were 

made for decay. No appreciable amount of decay would have occurred in 239Pu or 240Pu. For 238Pu, 

less than 4% of the initial 238Pu activity would have decayed by 1983. Furthermore, 238Pu activity was 
Document No. ORAUT-OTIB-0049 Revision No. 02 Effective Date: 09/01/2020 Page 14 of 18

ATTACHMENT A

DETERMINATION OF SOLUBILITY PARAMETERS FOR SUPER S MODEL (continued)

only about 12% of the total activity from these three. Therefore, any decay adjustment would change 

the sample result by less than 1% so no adjustment was considered necessary. Lastly, four urine 

samples were collected on the day of the event with no indication of the time of collection. The time 

during the first day significantly affects the amount of time between exposure and sample. Therefore, 

the first day of urine samples was excluded from the dataset for modeling.

In order to determine the appropriate solubility parameters, intakes were calculated a number of times 

from either lung or urine data. All the intake calculations discussed were performed using a least 

squares fit of the applicable data.

A.3 LONG-TERM ABSORPTION PARAMETER

The first attempt to develop absorption parameters for the new type SS model was to simply use the 

default type S parameters from Publication 66. Not surprisingly, these parameters underestimated 

the long-term retention of the 241Am in the lungs (Figure A-1). Because the long-term retention was of 

interest, the slow absorption rate (Ss) was reduced. The Ss value was reduced by a factor of 10 and 

the 241Am intake calculated. The results for several iterations of this process (Table A-1) showed that 

once reduced below 1 × 10-6 there was essentially no difference in the results. Further, the fit using 

1 × 10-6 was better than that obtained using the ICRP type S default (Figure A-1).

Table A-1. 241Am intakes calculated from lung counts using different Ss absorption 

parameters.

Fr Sr Ss Intake

0.000998 100.1 1E–4 1,921.6

0.000998 100.1 1E–5 1,651.6

0.000998 100.1 1E–6 1,621.6

0.000998 100.1 1E–7 1,618.6

0.000998 100.1 1E–8 1,618.3
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Figure A-1. HAN-1 241Am lung data with calculated lung content using Publication 66 default 

absorption and Ss value of 1 × 10-6. 

A.4 SHORT-TERM ABSORPTION PARAMETERS

With the Ss value of 1 × 10-6 set to define the long-term retention of 241Am in the lungs, it was then 

necessary to develop the short-term absorption parameters. Using the same lung count data, the 

parameters were varied one at a time and the 241Am intake was calculated. The results are shown in 

Table A-2. 

Table A-2. 241Am intakes calculated from lung counts using different Fr and Sr

absorption parameters. 

Fr Sr Ss

Intake

(Bq)

0.000998 100.1 1E–6 1,621.6

0.000998 1 1E–6 1,621.6

0.00998 100.1 1E–6 1,635.8

It can be seen in Table A-2 that varying the Fr and Sr parameters had little effect on the calculated 

intake. Therefore, the lung count data are not a good means of determining the appropriate values for 

these parameters. This analysis then evaluated the 239Pu urine data. In a similar fashion to the lung 
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count data, the absorption parameters were varied and an intake was calculated. The results are 

shown in Table A-3.

Table A-3. 239Pu intakes calculated from urine data using different Fr and Sr 

absorption parameters.

Fr Sr Ss

Intake

(Bq)

0.000998 100.1 1E–6 10,377

0.000998 1 1E–6 43,800

0.00998 100.1 1E–6 1,055.9

Varying either Fr or Sr clearly has a large impact on the calculated intake. Fr had a larger effect 

because the intake changed by almost an order of magnitude for a factor of 10 change in Fr. For Sr, 

the intake only changed by a factor of about 4.4 for a factor of 100 change in the parameter. Because 

of this, it was decided the Fr value is the appropriate parameter to change for this type SS model and 

the ICRP type S default Sr value would be retained for this model. 

Remembering the intake calculated from lung count data was insensitive to changes in Fr and Sr, the 

intake value of 1,621.6 Bq 241Am calculated earlier will be the starting point for the Fr determination. 

That value was calculated with ICRP type S default values for Fr and Sr, and the Ss value set to 

1 × 10-6. Using the 241Am intake value and the 239Pu-to241Am activity ratio for the inhaled material, the 

corresponding 239Pu intake is 10,067.7 Bq of 239Pu. Fr can then be varied until the calculated intake is 

reasonably close to this value. Table A-4 shows the results of several iterations.

Table A-4. 239Pu intakes calculated from urine data using different Fr absorption 

parameters.

Fr Sr Ss

Intake

(Bq)

0.0001 100.1 1E–6 88,311

0.0008 100.1 1E–6 12,884

0.0009 100.1 1E–6 11,483

0.00100 100.1 1E–6 10,357

0.00102 100.1 1E–6 10,157

0.001028 100.1 1E–6 10,080

0.001029 100.1 1E–6 10,070

0.001030 100.1 1E–6 10,061

0.001301 100.1 1E–6 10,051

From these data, a value for Fr of 0.001029 was chosen because it yielded an intake that was closest 

to the 10,067.7 Bq target and further varying this parameter in increments of 0.000001 produced only 

modest change. The absorption parameters for the type SS model are then:

Fr = 0.001029, 

Sr = 100.1,and

Ss = 1 × 10-6. 

A.5 VERIFICATION OF TYPE SS MODEL PARAMETERS

Using these new type SS parameters and bioassay data from the HAN-1 case, the model was used to 

determine the plutonium intakes and calculate the expected bioassay measurements for comparison 
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to real data. This was done to verify that an intake calculated from plutonium urine data using the 

type SS plutonium parameters and converted, by activity ratios, to the equivalent 241Am intake that 

would produce a reasonable fit between the predicted 241Am lung retention (using type SS 

parameters) and the actual 241Am lung count data. An intake was first calculated using the urine data, 

which resulted in a 239Pu intake of 10,070 Bq. Then the theoretical urine results from that intake were 

calculated and compared to the actual 239Pu urine results. The two are shown in Figure A-2. Next, 

the 241Am intake associated with that 239Pu intake was calculated to be 1,622.0 Bq of 241Am (using the 

239Pu-to241Am activity ratio). With that intake and a 241Pu-to241Am activity ratio of 168, the 241Am lung 

content was calculated and compared to the lung measurements. The results are shown in

Figure A-3. 

Figure A-2. HAN-1 239Pu urine data with calculated urine content using type SS parameters.

The parameters appear to produce a reasonable fit to the HAN-1 lung and urine data that is 

consistent with the activity ratios of the inhaled material.

A.6 A NOTE ON CHELATION THERAPY

Carbaugh and LaBone (2003) reported chelation therapy was performed early for this individual but 

was determined to be ineffective. Because chelation was administered, consideration was given to 

removing some of the early urine samples for modeling purposes. All samples from May and June of 

1978 were considered for elimination. Various combinations caused the calculated intake to increase 
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or decrease in comparison with the full dataset. Most changes in intake were not large. For some of 

the largest, the Fr value was varied to adjust the calculated intake to that predicted from the chest 

count. However, this resulted in a poor fit to the samples that were taken long after the intake. 

Therefore, Carbaugh and LaBone’s conclusion that chelation was ineffective appears correct.

Figure A-3. HAN-1 241Am lung data with calculated lung content using type SS parameters.