ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Oak Ridge National 

Laboratory – Introduction

Document Number:

ORAUT-TKBS-0012-1

Effective Date: 08/11/2004

Revision No.: 00

Controlled Copy No.: ________

Page 1 of 7

Subject Expert: Robert E. Burns, Jr. 

Document Owner

Approval: Signature on File Date: 07/22/2004

Robert E. Burns, Jr., TBD Team Leader

Approval: Signature on File Date: 07/26/2004

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Date: 08/04/2004

Richard E. Toohey, Project Director

Approval: Signature on File Date: 08/11/2004

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

1.0 Introduction.................................................................................................................................

Page

4

1.1 Purpose ......................................................................................................................................4

1.2 Scope .........................................................................................................................................4
Effective Date: 08/11/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-1 Page 2 of 7

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

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

National Laboratory - Introduction. Initiated by 

Robert E. Burns, Jr.

Draft 06/15/2004 00-B Incorporates NIOSH review comments. Initiated 

by Robert E. Burns, Jr.

Draft 07/06/2004 00-C Incorporates additional NIOSH review comments. 

Initiated by Robert E. Burns, Jr.

08/11/2004 08/11/2004 00 First approved issue. Initiated by Robert E. 

Burns, Jr.
Effective Date: 08/11/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-1 Page 3 of 7

ACRONYMS AND ABBREVIATIONS

CEF Critical Experiments Facility

DOE U. S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

IREP Interactive RadioEpidemiological Program 

keV kilovolt-electron, 1,000 electron volts

MDA minimum detectable activity 

NIOSH National Institute of Occupational Safety and Health

NTA nuclear track emulsion, type A

ORAU Oak Ridge Associated Universities

ORNL Oak Ridge National Laboratory

RaLa radioactive lanthanum

TBD Technical Basis Document

U.S.C. United States Code
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1.0

1.1 PURPOSE

INTRODUCTION

Technical Basis Documents (TBDs) and Site Profile Documents are general working documents that 

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

of sites. They will be revised in the event additional relevant information is obtained about the 

affected site(s). These documents may be used to assist the National Institute for Occupational 

Safety and Health (NIOSH) in the completion of the individual work required for each dose 

reconstruction. 

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

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

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

Occupational Illness Compensation Program Act of 2000 [42 U.S.C. Sections 7384l(5) and (12)]. 

This Site Profile represents a specific support mechanism documenting historical practices at the Oak 

Ridge National Laboratory (ORNL), also historically known as the X-10 site. Dose reconstructors can 

use this Site Profile in the evaluation of both internal and external dosimetry data for unmonitored and 

monitored workers. The document also serves as a supplement to, or substitute for, individual 

monitoring data. It provides technical basis information to be used to evaluate the total occupational 

radiation dose for ORNL workers. This dose results from exposure to external and internal radiation 

sources in ORNL facilities, to diagnostic occupationally required X-ray examinations, and to on-site 

environmental sources. In addition, this Site Profile addresses doses that could have occurred while 

the worker was not monitored, or dose that could otherwise have been missed. 

1.2 SCOPE

Five TBDs comprise the ORNL Site Profile: Site Description, Occupational Medical Dose, 

Occupational Environmental Dose, Occupational Internal Dose, and Occupational External Dose. 

The Site Description TBD (ORAUT-TKBS-0012-2) presents a brief description of the facilities and 

processes at ORNL since the early 1940s. 

The Oak Ridge Graphite Reactor, which was to be a pilot plant for the larger plutonium production 

reactors at the Hanford site, achieved initial criticality on November 4, 1943. The Graphite Reactor 

served only briefly in its role as a pilot plant, and quickly became an essential tool for basic research 

and for radioisotope production. The Graphite Reactor was the first of many reactors to operate at the 

ORNL site as the Laboratory expanded its research into the use of nuclear reactors in a number of 

domains including energy, propulsion systems, materials research, and radioisotope production. In 

addition, ORNL operated the Critical Experiments Facility (CEF) at the Y-12 site from mid-1950 until 

1987. The CEF supported experiments in design of various reactors at ORNL and elsewhere. 

A large part of the activities and operations at ORNL has been research and development into 

chemical technologies for separation of materials from irradiated nuclear fuels and liquid waste 

streams. ORNL developed many of the solvent extraction processes adopted at the Nation’s 

plutonium production facilities, and at one time the facility was a substantial provider of radioisotopes 

for industry and research. ORNL also produced stable isotopes using Calutrons at the Y-12 site. 

Isotope sales were eventually scaled back to only highly specialized materials, such as 252Cf from the 

High Flux Isotope Reactor, which was separated and packaged in the Radiochemical Engineering 

Development Center. Between 1944 and 1956, the Radioactive Lanthanum (RaLa) program was 
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carried out at ORNL to produce large quantities of 140Ba/La for use in weapons dynamics studies at 

the Los Alamos National Laboratory. The RaLa program involved dissolving short-decay uranium fuel 

slugs irradiated in either the ORNL Graphite Reactor or the production reactors at the Hanford site. 

ORNL has operated several accelerators including the 86-inch cyclotron at the Y-12 site, the Oak 

Ridge Isochronous Cyclotron, the Holifield Heavy Ion Research Facility, and the Oak Ridge Electron 

Linear Accelerator. Other smaller accelerators have also been used for such applications as 

dosimetry research and waste assay research. 

Waste handling practices at ORNL evolved as the scope and duration of its mission expanded. 

Gaseous wastes were initially discharged via local stacks and vents before a centralized offgas 

treatment system began operating in 1950. Liquid wastes were originally handled using a system of 

tank farms and settling basins to treat wastes before discharge into White Oak Creek. More liquid 

waste treatment facilities were added over time. A number of trenches, burial grounds, and Solid 

Waste Storage Areas have been at ORNL for the disposal of solid wastes. 

The Occupational Medical Dose TBD (ORAUT-TKBS-0012-3) provides information on doses workers 

received from X-rays that were required as a condition of employment. These X-rays were included in 

pre-employment screenings, annual physical exams, and termination exams. These X-ray exams 

were initially performed at the local hospital in Oak Ridge, where photofluorographic techniques 

appear to have been used. The Laboratory took over with its own X-ray equipment on October 3, 

1947, and those examinations were conventional exposures. Oak Ridge Hospital, as it was originally 

known, became what is now known as Methodist Medical Center of Oak Ridge in 1959. 

Chest X-rays have always been an element of employment-related physical examinations conducted 

by ORNL. However, the frequency of these exams and the workers who received them have varied. 

It appears that all workers have been required to have a chest X-ray as part of their preplacement 

examination. In addition, chest X-rays were performed annually and as part of termination 

examinations before 1963, though employees were allowed to waive these examinations in some 

cases. After 1963, the ORNL conducted routine chest X-rays only for preplacement exams and 

workers involved in respiratory protection programs, such as the asbestos program that began in 

1976. The frequency of chest X-rays for workers in the asbestos program has varied over time. From 

1976 to November of 1990, it was every 3 years. From November of 1990 to 2002, it depended on 

the worker’s age: every 3 years for workers under 40, every 2 years for workers 40 to 49, and 

annually for workers over 49. In 2002 the frequency for asbestos workers changed again to annually 

for workers 45 and over. 

From April 6, 1950, to September 23, 1953, lumbar spine X-rays were included in preplacement 

examinations for craft employees (such as pipe fitters, carpenters) to determine if they had preexisting back problems. These X-rays were in addition to the chest X-ray included in the 

preplacement examination for other employees. 

Both the X-ray equipment and the techniques used for X-rays covered by this TBD have changed 

over the years. These factors were taken into account in determining the dose that a worker would 

have received from an X-ray. When there was doubt about the technique used, assumptions were 

made to ensure the worker’s dose was not underestimated. The parameters considered include the 

tube current and voltage, exposure time, filtration, source to skin distance, the view (posterior-anterior 

or lateral), and other factors that could affect the dose received by the worker. 
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Doses to the various organs exposed from the different X-ray examinations a worker could have 

received have been estimated and presented in tables for convenient reference by the dose 

reconstructors. 

The Occupational Environmental Dose TBD (ORAUT-TKBS-0012-4) applies to workers who were not 

monitored for external or internal radiation exposure. Environmental dose is that which workers could 

have received while being outdoors on the ORNL site from inhalation of radioactive materials in the 

air, direct radiation from airborne releases, or direct radiation in the vicinity of process buildings and 

waste handling areas. 

The Occupational Environmental Dose TBD provides a table of annual average airborne 

concentration and intake data for 131I, tritium, and particulate mixed fission products. The 

concentration data are derived from a combination of conservative assumptions of airborne releases 

and dispersion and on-site air-monitoring data. Annual intakes reflect assumptions of continuous 

exposure for a period of 2,000 hours per year at a respiration rate of 1.2 cubic meters per hour. The 

intake values given for tritium include a multiplier of 1.5 to account for absorption through the skin. 

In addition, the Occupational Environmental Dose TBD provides a table of annual average exposure 

rates for the ORNL site. These values are averages of exposure rates measured at a large number of 

locations in the main process areas. The measurements began early in the Laboratory’s history and 

continued through 1984. They began as periodic measurements using portable instrumentation and 

evolved to continuous measurements with dosimeters. The values include contributions from the 

settling basin and process buildings where local exposure rates were much higher than ambient levels 

elsewhere. They do not include data from remote monitoring locations representing background 

levels, and thus should represent conservative estimates for an unmonitored individual moving about 

on the ORNL site. 

The Occupational Internal Dosimetry TBD (ORAUT-TKBS-0012-5) discusses ORNL’s in vitro and in 

vivo monitoring programs and facilities, including counting methods, minimum detectable activities 

(MDAs), and reporting practices. Environmental levels of uranium and 137Cs are also discussed. For 

in vitro methods, MDAs were established by extracting information from a database of raw bioassay 

data compiled by ORNL. This database was queried for data from historical bioassay analyses 

including background counts, instrument efficiencies, chemical yields (recoveries), sample volumes, 

and aliquot volumes. The queries returned over 66,000 records spanning the period from 1947 

through 1988. The records were screened to eliminate those that were incomplete or contained gross 

errors. The remaining records were used to calculate MDAs for individual analyses. The individual 

MDA data were then analyzed collectively for common analyses to establish representative values for 

a given analyte and period. MDAs are in terms of disintegrations per minute per 24-hour sample for 

both urine and fecal samples. The TBD provides a table of representative MDA values for specific 

analytes and periods for dose reconstructors to use in assessment for the period before 1989. It also 

includes a table of the annual average MDA values computed for specific analytes from the 

information obtained from the database. After 1989, ORNL computed MDAs for each in vitro sample 

analysis and reported them as part of the results. The TBD includes a table of typical MDAs for 

various analytes for the post-1989 period. 

The TBD provides descriptions and MDAs for a number of the in vivo counting systems and 

geometries employed at ORNL. Plots of MDA versus chest wall thickness are provided for the ORNL 

germanium lung counter for 235U, 238U, 238Pu, and 241Am, and for the phoswich lung counter for 238Pu 

and 241Am. The MDA values cited in the Occupational Internal Dosimetry TBD were taken primarily 

from ORNL’s own TBD for in vivo monitoring. Some values came from other ORNL reports. 
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The Occupational External Dosimetry TBD (ORAUT-TKBS-0012-6) describes ORNL’s personnel 

monitoring methods and practices for the period from October 1943 to the present. It covers the 

various dosimeters used at ORNL, worker badging practices, dosimeter exchange frequencies, dose 

quantities and algorithms, dosimeter calibration practices, and reporting and administrative practices. 

The TBD contains detailed information on mixed neutron/photon radiation fields present in several 

ORNL facilities. Photon and neutron energy groups to be assumed when entering worker dose 

histories into the IREP program are given. Neutron energy spectra are discussed vis-à-vis the 500-

keV response threshold for nuclear track emulsion, type A (NTA) film. Neutron-to-photon dose ratios 

are provided for use in cases where neutron monitoring could have been inadequate, such as the use 

of NTA film for monitoring in low-energy fields. The TBD provides limits of detection to be assumed 

for beta-gamma and neutron dosimetry for estimating missed dose. Adjustments to reported dose 

values for input into the IREP program are discussed, such as the use of exposure-to-organ-dose 

conversion factors for deep dose values for the period before DOE Laboratory Accreditation Program 

accreditation, adjustment of open window dose values for different calibration practices, and 

adjustment of neutron dose values for different neutron quality factors used in different eras.