ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

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DOE Review Release 03/27/2009

 

Document Title:

Potential Missed Dose to Nuclear Weapons

Assemblers at the Y-12 Plant During the 

Period from 1958 to 1990

Document Number: ORAUT-OTIB-0074

Revision: 00

Effective Date: 03/13/2009

Type of Document OTIB

Supersedes: None

Subject Expert(s): George D. Kerr, William G. Tankersley 

Site Expert(s): N/A

Approval: Signature on File Approval Date: 03/06/2009

George D. Kerr, Document Owner

Concurrence: Signature on File Concurrence Date: 03/05/2009

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 03/05/2009

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 03/11/2009 

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 03/13/2009

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

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

THE PRIOR REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 2 of 10

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

03/13/2009 00 New technical information bulletin that provides bounding estimates 

of potential missed radiation doses to weapons assemblers who 

worked in the dry room of Building 9204-2 at the Oak Ridge Y-12 

Plant during the period from 1958 to 1990. Incorporates formal 

internal review comments. No changes occurred as a result of 

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

Manager. Initiated by George D. Kerr.
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 3 of 10

TABLE OF CONTENTS

SECTION TITLE PAGE

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

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

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

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

4.0 Missed Dose Estimates...............................................................................................................7

5.0 Attributions and Annotations .......................................................................................................9

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

LIST OF TABLES

TABLE TITLE

3-1 Transmission factors of various clothing for uranium beta particles..........................................

PAGE

7

4-1 Estimates of potential missed dose to weapons assemblers at the Y-12 Plant, 1958 to 

1990.........................................................................................................................................7
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 4 of 10

ACRONYMS AND ABBREVIATIONS

d day

DOE U.S. Department of Energy

ft foot

hr hour

IREP Interactive RadioEpidemiological Program

keV kiloelectron volts

mrem millirem

NIOSH National Institute for Occupational Safety and Health

OCAS Office of Compensation Analysis and Support 

ORAU Oak Ridge Associated Universities

qtr quarter

RPG radiation protection guideline

SRDB Ref ID Site Research Database Reference Identification (number)

TIB technical information bulletin

U.S.C. United States Code

wk week

Y-12 Y-12 Plant, now the Y-12 National Security Complex

yr year

§ section or sections
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 5 of 10

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 

historic 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 TIB is to provide information on potential missed dose to nuclear weapons

assemblers at the Y-12 Plant during the period from 1958 to 1990. The information that was used in 

the preparation of this TIB was obtained primarily from interviews of several former weapons

assemblers and a former supervisor of weapons assemblers at the Y-12 Plant (Tankersley 2006, 

2009). 

3.0 BACKGROUND INFORMATION

The Y-12 National Security Complex, formerly the Y-12 Plant, performs missions that are vital to DOE 

(TAPP 2003; Alspaugh 2001). Every nuclear weapon in the current U.S. stockpile contains 

components that were manufactured at the Y-12 facility (Alspaugh 2001). Y-12 also serves as the 

nation’s assembly and disassembly plant for nuclear secondary components (Alspaugh 2001). 

There are two basic types of nuclear weapons. The first type produces explosive energy through 

nuclear fission alone. These weapons are commonly called fission bombs, atomic bombs, or 

A-bombs. The second basic type produces most of the explosive energy through nuclear fusion. 

These weapons are commonly known as thermonuclear bombs, hydrogen bombs, or H-bombs. 

Thermonuclear weapons depend on a fission stage to initiate the explosive release of fusion energy. 

The fission stage is called the primary, and the fusion stage of the weapon is called the secondary. 

The secondary stages in thermonuclear weapons were installed at Y-12, and the partially assembled 

weapons were shipped off the site for further installation of the primaries.

Weapons component assembly and disassembly were performed primarily in Buildings 9204-2 and 

9204-2E (ORAUT 2007a; Wilcox 2001). Dry boxes with glove ports were used by Y-12 workers 

during the assembly of the earliest thermonuclear weapons (Wilcox 2001). These dry boxes were 

later replaced by a dry room with moisture levels controlled to within parts per million range (Wilcox 

2001). Personnel inside the dry room wore airtight ventilated suits similar to those worn by astronauts 

to prevent body moisture from damaging weapons components during assembly of secondary stages

(Wilcox 2001). The interviews with former assembly personnel indicate that the dry room at Y-12 was

built in late 1958 or early 1959 (exact date uncertain) in Building 9204-2 (Tankersley 2006, 2009).
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 6 of 10

The following bulleted items provide other information that was obtained in the interviews of several 

former weapons assemblers and a former supervisor of weapons assemblers at the Y-12 Plant

(Tankersley 2006). 

• Dry room work was cumbersome at best, and an attempt was made to minimize the time 

in the ventilated suits. The total time spent in the suits was typically less than or equal to 

approximately 4 hr/d.

• The ventilated suit was rather heavy. It was made of plastic or rubber and had a weight similar 

to that of muslin. Personnel who were wearing ventilated suits took off outer clothing down to 

their underwear. 

• Film badges and extremity dosimeters were not worn during assembly operations because 

they would be damaged by the profuse sweating by personnel while suited. The airflow in 

the dry room was quite high, but the dry room was not air conditioned. 

• There were usually two to three individuals in the dry room at any one time. Much of the work 

was hands on, but individuals who were not involved in the assembly would step back until 

they were needed, then move up to carry out their part of the assembly. 

• No one took unnecessary exposures during assembly. Health physicists stayed in the dry 

room and made constant surveys of the exposure and dose rates. Assemblers were not 

overly concerned because the penetrating whole-body doses were determined to be small.

• Time in a dry room without a film badge was about 15 to 20 hr/wk. The number of hours within 

3 ft of a device under construction was approximately 10 hr/wk, and the time in direct contact 

with a device was about 1 to 2 minutes per assembly.

The dose rates below are taken from actual measurements made on secondary stages handled at the 

Y-12 facility during the period of interest (Kerr 2007). The set of measurements giving the largest 

dose rates is used here to provide bounding values for the potential missed dose to assemblers. 

These dose rates at various distances are as follows:

Distance

Photons 

(mrem/hr)

Beta particles

(mrem/hr)

Contact 8 197

1 ft 1 7

3 ft 0.1 0.6

For dose reconstruction, estimates of the radiation doses to the extremities are necessary as well as 

estimates of the doses to the whole body and skin of the whole body. The beta doses to the body, 

face, and extremities must be corrected for shielding by the ventilated suit, clear plastic headpiece,

and gloves the assemblers wore (Table 3-1). Transmission factors of various clothing items for the 

very energetic beta particles from uranium are summarized in Table 3.1. These data were taken from 

two recent reports on radiological protection for workers at uranium facilities (Rich et al. 1988; DOE 

2004). The application of certain selected transmission values from Table 3-1 in the estimation of 

missed dose to nuclear weapon assemblers at the Y-12 Plant is discussed in Section 4.0. 
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 7 of 10

Table 3-1. Transmission factors of various clothing for uranium beta particles.

Clothing

Transmission 

factor Reference

Face shield 0.41 Rich et al. 1988

Vinyl surgeon’s gloves 0.95 DOE 2004

Latex surgeon’s gloves 0.87 DOE 2004

Two pairs of gloves plus liner 0.60 Rich et al. 1988

Lead-loaded, 10-mil lead equivalent 0.77 DOE 2004

Lead-loaded, 30-mil lead equivalent 0.13 DOE 2004

Pylox (vinyl) gloves 0.62 DOE 2004

Leather, medium weight 0.62 DOE 2004

White cotton gloves 0.89 DOE 2004

Two pairs of coveralls plus paper liner 0.80 Rich et al. 1988

Tyvek coveralls 0.98 DOE 2004

Durafab paper laboratory coat 0.96 DOE 2004

Laboratory coat (65% Dacron and 35% cotton) 0.91 Rich et al. 1988; DOE 2004

4.0 MISSED DOSE ESTIMATES

The dose rates at various distances from the secondary stage in the previous section of this report 

were used in the following estimates of potential missed dose to assemblers while working in the dry 

room at the Y-12 facility during the period from 1958 to 1990. It was assumed that the model 

individual spent a total of 10 hr/wk within 3 ft of the device under assembly. It is further assumed that 

5 hr/wk of the total of 10 hr/wk were spent at 1 ft from a device during hands-on work. The 1 to 2 

minutes during assembly that were spent in nearly direct contact with a device during hands-on work 

contributed insignificantly to the total missed dose. 

Use of the above assumptions resulted in a potential missed penetrating dose to the whole body from 

photons equal to:

(0.1 mrem/hr)(5 hr/wk) + (1 mrem/hr)(5 hr/wk),

which is 5.5 mrem/wk, 72 mrem/qtr, or 290 mrem/yr (Table 4-1). These estimates are also used as 

the photon radiation dose to the head and face (Table 4-1). 

Table 4-1. Estimates of potential missed dose (mrem) to weapons

assemblers at the Y-12 Plant, 1958 to 1990.

a

Dose equivalent component

Dose equivalent

Weekly Quarterly Yearly

Photon radiation dose to whole body 5.5 72 290

Beta radiation dose to skin of whole body 32 420 1,700

Photon radiation dose to head and face 5.5 72 290

Beta radiation dose to skin of head and face 16 210 840

Photon radiation dose to hands 40 520 2,100

Beta radiation dose to skin of hands 740 9,600 39,000

a. Dose estimates greater than 100 mrem are rounded to two significant figures.

For the nonpenetrating dose to the whole body from beta particles, a transmission factor of 0.85 was 

assumed for the ventilated suit, which is the approximate average value of the transmission factors of 

0.80 for two pairs of coveralls plus a paper liner and 0.91 for a laboratory coat (Table 3-1). Therefore, 

the potential missed nonpenetrating dose from beta particles to the skin of the whole body would be:
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 8 of 10

0.85 × [(0.6 mrem/hr)(5 hr/wk) + (7 mrem/hr)(5 hr/wk)],

which is 32 mrem/wk, 420 mrem/qtr, or 1.7 rem/yr (Table 4-1).

For the nonpenetrating dose to the skin of the head and face from beta particles, a transmission factor 

of 0.41 for a face shield in Table 3.1 was assumed to be applicable to the clear plastic headpiece of 

the airtight ventilated suit worn by the assemblers. Therefore, the potential missed nonpenetrating 

dose from beta particles to the skin of the head and face would be:

0.41 × [(0.6 mrem/hr)(5 hr/wk) + (7 mrem/hr)(5 hr/wk)],

which is 16 mrem/wk, 210 mrem/qtr, or 840 mrem/yr (Table 4-1).

The Y-12 radiation protection guideline (RPG) for the dose to the whole body from photons was 

5 rem/yr, and the RPG for the dose to the skin of the whole body and the face from both photons 

and beta particles ranged from a low of 15 rem/yr to a high of 50 rem/yr during this period (ORAUT 

2007b). The total missed dose to the skin of the whole body or the head and face is the sum of the 

penetrating and nonpenetrating doses in Table 4.1 from photons and beta particles, respectively. 

The potential missed dose to the hands or extremities from photons from direct contact with a device 

during hands-on work is estimated to be:

(8 mrem/hr)(5 hr/wk),

which is 40 mrem/wk, 520 mrem/qtr, or 2.1 rem/yr. For the dose to the hands from beta particles, a 

transmission factor of 0.75 was assumed for the gloves assemblers wore, which is the approximate 

average value of the transmission factors for Pylox or leather gloves and 0.91 for white cotton gloves 

(Table 3-1). Therefore, the potential missed dose to the hands from beta particles would be:

0.75 × (197 mrem/hr)(5 hr/wk),

which is 739 mrem/wk, 9.6 rem/qtr, or 39 rem/yr (Table 4-1). The total missed dose to the hands 

(extremities) from photons and beta particles would be approximately 41 rem/yr, which compares to 

RPGs for the extremities of 75 rem/yr before 1988 and 50 rem/yr starting in 1988 (ORAUT 2007b). 

The nuclear weapon assemblers at the Y-12 Plant wore a film badge dosimeter when they were not 

working in the dry room. Thus, the dose estimates given here are only estimates of missed dose 

while the assemblers were working in the dry room and were not wearing their film badge dosimeters. 

The exposure geometry for the missed dose estimates presented here should be treated as an 

anterior-posterior (AP) or front-to-back irradiation of the body. The beta particles should be 

considered to have energies greater than 15 keV and the photons should be considered to have 

energies ranging from 30 to 250 keV (ORAUT 2006, Table 6.3.4.1-1). Because the missed dose 

estimates for an assembler who worked in the dry room without wearing a film badge dosimeter are 

bounding estimates or best estimates based on the available information, they should be entered as

constant values into the calculations using the NIOSH-Interactive RadioEpidemiological Program 

(NIOSH-IREP). NIOSH-IREP is a web-based computer program that estimates the probability that an 

individual’s cancer was caused by his or her radiation exposure. Discussions of NIOSH-IREP can be 

found in a number of technical documents posted on NIOSH’s Office of Compensation Analysis and 

Support (OCAS) web site at www.cdc.gov/niosh/ocas.
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 9 of 10

5.0 ATTRIBUTIONS AND ANNOTATIONS

All information requiring identification was addressed via references integrated into the reference 

section of this document.
Document No. ORAUT-OTIB-0074 Revision No. 00 Effective Date: 03/13/2009 Page 10 of 10

REFERENCES 

Alspaugh, D., 2001, Overview of the DYMCAS, the Y-12 Material Control and Accountability System, 

Y/SW-0077, BWXT Y-12, Y-12 National Security Complex, Oak Ridge, Tennessee, July. 

[SRDB Ref ID: 47091]

DOE (U.S. Department of Energy), 2004, Guide of Good Practices for Occupational Radiological 

Protection in Uranium Facilities, DOE-STD-1136-2004, Washington, D.C. [SRDB Ref ID: 

18881]

Kerr, G. D., 2007, “Bounding Dose Rates for Weapon Assemblers Working in the Y-12 Dry Room,” 

documented communication with M. H. Chew, (M. L. Chew and Associates), Kerr Consulting, 

Knoxville, Tennessee, February 27. [SRDB Ref ID: 31375]

ORAUT (Oak Ridge Associated Universities Team), 2006, Technical Basis Document for the Y-12 

National Security Complex – Occupational External Dosimetry, ORAUT-TKBS-0014-6, Rev. 

00 PC-3, Oak Ridge, Tennessee, May 11.

ORAUT (Oak Ridge Associated Universities Team), 2007a, Y-12 National Security Complex – Site 

Description, ORAUT-TKBS-0014-2, Rev. 02, Oak Ridge, Tennessee, November 8.

ORAUT (Oak Ridge Associated Universities Team), 2007b, Historical Evaluation of the Film Badge 

Dosimetry Program at the Y-12 Plant in Oak Ridge, Tennessee: Part 3 – Beta Radiation, 

ORAUT-OTIB-0046, Rev. 00, Oak Ridge, Tennessee, June 22.

Rich, B. L., S. L. Hinnefeld, C. R. Lagerquist, W. G. Mansfield, L. H. Munson, E. R., Wagner, and E. J. 

Vallario, 1988, Health Physics Manual of Good Practices for Uranium Facilities, EGG-2530, 

EG&G Idaho, Idaho National Engineering Laboratory, Idaho Falls, Idaho, June. [SRDB Ref ID: 

1781]

Tankersley, W. G., 2006, “Y-12 Assembly/Disassembly Conferences and Telephone Conversations” 

documented communications with G. D. Kerr (Oak Ridge Associated Universities) March 16, 

2006 through March 23, 2006, Oak Ridge Associated Universities Team, Oak Ridge, 

Tennessee. [SRBD Ref ID: 57448]

Tankersley, W. G., 2009, “Dry Room Locations at the Y-12 Plant from 1958 to 1990” documented 

communications with G. D. Kerr (Oak Ridge Associated Universities) January 27, 2009, Oak 

Ridge Associated Universities Team, Oak Ridge, Tennessee. [SRDB Ref ID: 58676]

TAPP (Thomas and Associates Preservation Planners), 2003, Y-12 National Security Complex 

National Historic Preservation Act Historic Preservation Plan, Y/TS-1983, Y-12 National 

Security Complex, Oak Ridge, Tennessee. [SRDB Ref ID: 19331]

Wilcox, W. J. Jr., 2001, An Overview of the History of Y-12 – 1942-1992: A Chronology of Some 

Noteworthy Events and Memoirs, American Museum of Science and Energy, Oak Ridge, 

Tennessee, August. [SRDB Ref ID: 9609]