ORAU Team

Dose Reconstruction Project for NIOSH

Technical Basis Document for Paducah Gaseous Diffusion 

Plant - Introduction

Document Number:

ORAUT-TKBS-0019-1 

Effective Date: 08/30/2006

Revision No.: 00 PC-1 

Controlled Copy No.:

Page 1 of 6 

_______

Subject Expert: Jay J. Maisler

Document Owner

Approval: Signature on File Date: 

 Jay J. Maisler, TBD Team Leader 

09/08/2004

Approval: Signature on File Date: 

 Judson L. Kenoyer, Task 3 Manager

09/07/2004

Concurrence: Signature on File Date: 

 Richard E. Toohey, Project Director

09/08/2004

Approval: Signature on File Date: 

 James W. Neton, Associate Director for Science

09/09/2004

Supersedes:

 None

TABLE OF CONTENTS

SECTION TITLE

RECORD OF ISSUE/REVISIONS .......................................................................................................

PAGE

2

ACRONYMS AND ABBREVIATIONS..................................................................................................3

1.1 PURPOSE ...............................................................................................................................4

1.2 SCOPE ....................................................................................................................................5
Effective Date: 08/30/2006 Revision No. 00 PC-1 Document No. ORAUT-TKBS-0019-1 Page 2 of 6

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION

DATE

EFFECTIVE 

DATE

REV.

NO. DESCRIPTION

Draft 05/17/2004 00-A New technical basis document for the Paducah

Gaseous Diffusion Plant – Site Profile. Initiated 

by Jay J. Maisler.

Draft 06/08/2004 00-B Addressed OCAS comments. Initiated by Jay J. 

Maisler.

Draft 07/07/2004 00-C Addressed additional OCAS comments. Initiated 

by Jay J. Maisler.

09/09/2004 09/09/2004 00 First approved issue. Initiated by Jay J. Maisler.

09/09/2004 08/30/2006 00 PC-1 Approved page change revision to review against 

Worker Outreach comments and periodic 

revision. Updates required language on page 4 

in Section 1.0. No sections were deleted. No 

further changes occurred as a result of internal 

formal review. This revision results in no change 

to the assigned dose and no PER is required. 

Training required: As determined by the Task 

Manager. Initiated by Paul A. Szalinski. 

Approval: 

Daniel Mantooth, TBD Team Leader

Signature on File_____________ 08/16/2006 

John M. Byrne, Task 3 Manager

Richard Merrill Signature on File for 08/16/2006 

Edward F. Maher, Task 5 Manager

Signature on File _______________ 08/16/2006

Kate Kimpan, Project Director

Signature on File_________ __ 08/17/2006 

James W. Neton, Associate Director for Science

Signature on File___________ __ 08/30/2006 
Effective Date: 09/09/2004 Revision No. 00 Document No. ORAUT-TKBS-0019-1 Page 3 of 6

ACRONYMS AND ABBREVIATIONS 

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

DOE Department of Energy

DOL Department of Labor

GM Geiger-Muller 

HHS Department of Health and Human Services

ICPMS Inductively Coupled Plasma Mass Spectrometry

kerma kinetic energy released per unit mass

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

OWCP Office of Worker Compensation

PGDP Paducah Gaseous Diffusion Plant

TBD technical basis document

TLD thermoluminescent dosimeter

TRU transuranic
Effective Date: 08/30/2006 Revision No. 00 PC-1 Document No. ORAUT-TKBS-0019-1 Page 4 of 6

1.1

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

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

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

dose reconstructions for particular sites or categories of sites. The documents will be revised in the 

event additional relevant information is obtained about the affected site(s). These documents may be 

used to assist NIOSH staff in the completion of the individual work required for each dose 

reconstruction.

PURPOSE

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

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

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

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

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

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

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

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

facility encompassed by EEOICPA.

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

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

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

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

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

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

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

determined in accordance with the POC [probability of causation1

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

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

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

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

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

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

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

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

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

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

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

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

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the POC guidelines (nor the dose 

reconstruction regulation) define “performance of duty” for DOE employees with a covered cancer or 

restrict the “duty” to nuclear weapons work.

• Radiation from naturally occurring radon present in conventional structures

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

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
Effective Date: 09/09/2004 Revision No. 00 Document No. ORAUT-TKBS-0019-1 Page 5 of 6

1.2

The Paducah Site Profile is divided into six major sections: this Introduction, Site Description, 

Occupational Medical Dose, Occupational Environmental Dose, Occupational Internal Dose, and 

Occupational External Dose. Some sections are accompanied by an attachment that provides the 

critical data for the specialists reconstructing the doses.

SCOPE

The Site Description TBD (ORAUT-TKBS-0019-2) is a brief description of the facilities and processes 

used in processing and enriching uranium. The purpose of the gaseous diffusion plant has been and 

continues to be the enrichment of uranium, initially for military applications and subsequently for 

commercial nuclear reactor fuel. PGDP enriches feed material in the form of uranium hexafluoride 

(UF6) gas from approximately 0.711% 235U up to about 2.5% 235U. The enriched product from PGDP 

was sent to other U. S. Department of Energy (DOE) gaseous diffusion plants at Portsmouth, Ohio, 

and Oak Ridge, Tennessee, for further enrichment. Some feed material was recycled uranium

obtained from spent reactor fuel.

The Occupational Medical Dose TBD (ORAUT-TKBS-0019-3) provides information about the dose 

individual workers received from X-rays required as a condition of employment. The PGDP 

occupational medicine program required pre-employment and regular diagnostic chest X-ray 

examinations. The examinations consisted of one posterior-anterior and one lateral chest projection. 

In addition to parts of the body exposed in the primary beam of an X-ray machine, other tissues 

receive some dose from secondary radiation. Secondary radiation consists of X-rays that are 

scattered from surrounding materials or that escape from the source assembly. In this TBD, tables 

are provided that list favorable to claimant estimated dose equivalents to organs of the body that 

result from single and combined posterior-anterior and lateral chest X-rays for male and female PGDP 

employees. The tables are derived from an assessment of the air kerma at the source-to-skin 

distance, based on specific operating parameters for the facility, insofar as these are known.

The Occupational Environmental Dose TBD (ORAUT-TKBS-0019-4) applies to workers who were not 

monitored for external or internal radiation exposure. The environmental dose is the dose workers 

received when working outside the buildings on the site from inhalation of radioactive materials in the 

air and direct radiation exposure from sources, such as the depleted uranium hexafluoride cylinders in 

storage. 

Inhalation of environmental radionuclides results in internal dose to the whole body or body organs. 

The internal dose for workers outside of the facilities was determined from the air concentrations 

resulting from the releases from stacks, individual building releases, and from the purge cascade and 

other operations at PGDP. Unmonitored workers may have been exposed to occupational doses 

internally from on-site releases into the air. Air concentrations of radionuclides were determined using 

annual environmental reports and are provided from 1952 through 1996. Values for airborne 

concentrations and annual intakes are provided for total uranium and 99Tc.

Site annual environmental reports, health physics surveys, and other reports were reviewed for data 

that would be useful in reconstructing ambient radiation levels. Ambient radiation dose rates includes 

natural background radiation and from sources within the facility.

PGDP personnel have annually compared these data with thermoluminescent dosimeter (TLD) data 

from offsite locations and literature values for state and regional exposure levels. The determination 

has always been that onsite ambient radiological conditions as measured at the security fence are not 

significantly different from offsite, state, and regional annual exposure levels. This is attributed to the 

geology of the region around PGDP. Exceptions to this observation have been monitoring locations 
Effective Date: 09/09/2004 Revision No. 00 Document No. ORAUT-TKBS-0019-1 Page 6 of 6

near depleted uranium cylinder storage yards in recent years. These locations show an increase in 

external exposure as the inventory of depleted uranium increased. The approach for estimating 

external dose using this information is provided in the TBD.

The Occupational Internal Dosimetry TBD (ORAUT-TKBS-0019-5) describes the internal dosimetry 

program at PGDP. The primary method for monitoring employees for intakes of radionuclides at 

PGDP was urine bioassay, which was instituted at the start of enrichment operations and has 

continued to the present day. However, the focus of the monitoring program in the early years was 

the detection of excreted soluble uranium. When monitoring for less soluble isotopes of uranium and 

transuranic (TRU) elements was necessary, in vivo methodologies were implemented to supplement 

the excretion data. These methods were primarily whole-body counting and chest (lung) counting.

Until the mid-1980s, action levels were set based on the amount of uranium excreted. Later, intakes 

and doses were assessed based upon both in vivo and in vitro monitoring results. Data are available 

from 1952 to the present for both in vivo and in vitro analysis records and associated interpretations.

A review of in-house procedures used to assess the concentration of uranium in urine indicates that a 

variety of quality control steps were an integral part of the process. Therefore, the in vitro results from 

in-house processing, typically reported in units of micrograms of uranium per liter, are considered to 

be generally reliable. However, interpretation of those results can be difficult, primarily because of 

uncertainty regarding enrichment and solubility, the contribution of environmental uranium, and 

because samples were collected at work and during the middle of the work week, meaning that crosscontamination and the inability to unfold soluble from insoluble intake fractions contribute to the 

uncertainty.

Guidance on selection of source terms is provided in the TBD. Input parameters for the interpretation 

of in vivo and in vitro measurement results are presented, including instructions for assessing dose for 

both monitored and unmonitored employees. The detection limits of the various in vivo and in vitro

methodologies and potential missed dose are discussed. Existing data analysis is summarized and 

significant incidents with internal dose potential are identified.

The Occupational External Dosimetry Program TBD (ORAUT-TKBS-0019-6) describes the program 

for measuring skin and whole body doses to the workers from sources that were external to the body. 

The methods used at the PGDP have also evolved over the years as new techniques and equipment 

have been developed. In addition, concepts in radiation protection have changed. The dose 

reconstruction, PGDP practices and policies, and dosimeter types and technology for measuring the 

dose from the different types of radiation are discussed in this section. Attention is given to the 

evaluation of doses measured from exposure to beta, gamma, and neutron radiation.

Sources of bias, workplace radiation field characteristics, responses of different beta/gamma and 

neutron dosimeters in the workplace fields, and the adjustments to the recorded dose measured by 

these dosimeters during specific years are presented in detail. In addition, the sources of potential 

dose that could be missed because of the limitations of dosimetry systems and the methods of 

reporting low doses are presented as a function of dosimeter type, year, and type of radiation.