June 29, 2005 

Mr. David Staudt 

Center for Disease Control and Prevention 

Acquisition and Assistance Field Branch 

Post Office Box 18070 

626 Cochrans Mill Road – B-140 

Pittsburgh, PA 15236-0295 

Re: Contract No. 200-2004-03805, Task Order 1: Document No. SCA-TR-TASK1-0009c 

Draft Review of NIOSH Site Profile for the Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP) ― Final Integrated Version 

Dear Mr. Staudt: 

S. Cohen & Associates (SC&A, Inc.) is pleased to submit our Final Integrated Version of the Review 

of NIOSH Site Profile for the Atomic Energy Operations at the Iowa Army Ammunition Plant 

(IAAP). This draft review of the IAAP site profile combines two partial preliminary reports 

reviewing Rev. 01 of the TBD that SC&A submitted to the National Institute of Occupational 

Safety and Health and the Advisory Board on Radiation and Worker Health on April 18 and 

April 22, 2005 (SCA-TR-TASK1-0009 and SCA-TR-TASK1-0009b, respectively). It also 

includes some new elements of the review that SC&A has added since that time based on 

comments on the preliminary reviews, as well as site expert interviews that have been 

declassified by the Department of Energy. 

Sincerely, 

John Mauro, PhD, CHP 

Project Manager 

cc: P. Ziemer, PhD, Board Chairperson 

Advisory Board Members 

L. Wade, PhD, NIOSH 

L. Elliott, NIOSH 

J. Neton, PhD, NIOSH 

S. Hinnefeld, NIOSH 

N. Barone, NIOSH 

A. Brand, NIOSH 

H. Behling, PhD, SC&A 

J. Lipzstein, PhD, SC&A 

A. Makhijani, PhD, SC&A 

J. Fitzgerald, Saliant 

K. Robertson-DeMers, CHP, Saliant 

S. Ostrow, PhD, SC&A 

K. Behling. SC&A 

Project File (ANIOS/001/09)
 
 

 

 

 

 

Final Draft 

ADVISORY BOARD ON 

RADIATION AND WORKER HEALTH 

National Institute of Occupational Safety and Health 

Review of NIOSH Site Profile 

for the 

Atomic Energy Operations at the Iowa Army Ammunition Plant (IAAP) 

Final Integrated Version 

Contract No. 200-2004-03805 

Task Order No. 1 

SCA-TR-TASK1-0009c
 

Prepared by 

S. Cohen & Associates 

6858 Old Dominion Drive, Suite 301 

McLean, Virginia 22101 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755 

June 2005 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on Radiation and 

Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, the ABRWH and its 

contractor, SC&A, caution the reader that at the time of its release, this report is pre-decisional and has not been 

reviewed by the Board for factual accuracy or applicability within the requirements of 42 CFR 82. This implies that 

once reviewed by the ABRWH, the Board’s position may differ from the report’s conclusions. Thus, the reader 

should be cautioned that this report is for information only and that premature interpretations regarding its 

conclusions are unwarranted. 
Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

2 of 92 

S. COHEN & ASSOCIATES: 

Technical Support for the Advisory Board on 

Document No. 

SCA-TR-TASK1-0009c 

Radiation & Worker Health Review of 

NIOSH Dose Reconstruction Program 

Effective Date: 

Draft – June 29, 2005 

Revision No. 0 (Draft) 

REVIEW OF NIOSH SITE PROFILE FOR THE 

ATOMIC ENERGY OPERATIONS AT THE IOWA 

ARMY AMMUNITION PLANT (IAAP) 

FINAL INTEGRATED VERSION 

Page 2 of 92 

Task Manager: ___________________ Date: _________

 Joseph Fitzgerald 

Supersedes: 

SCA-TR-TASK1-0009 and 

SCA-TR-TASK1-0009b 

Project Manager: _________________ Date: _________ 

John Mauro 
Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

3 of 92 

TABLE OF CONTENTS 

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

1.0 Executive Summary .............................................................................................................6 

2.0 Scope and Introduction ......................................................................................................10 

3.0 Assessment Criteria and Methods......................................................................................12 

3.1 Objectives ..............................................................................................................12 

3.1.1 Objective 1: Completeness of Data Sources .............................................12 

3.1.2 Objective 2: Technical Accuracy..............................................................12 

3.1.3 Objective 3: Adequacy of Data.................................................................12 

3.1.4 Objective 4: Consistency Among Site Profiles.........................................13 

3.1.5 Objective 5: Regulatory Compliance........................................................13 

3.2 A Chronology of Events ........................................................................................15 

3.2.1 Overall Review ..........................................................................................15 

3.2.2 Classified Review, April 12–13, 2005 .......................................................16 

4.0 Site Profile Strengths .........................................................................................................17 

5.0 Findings..............................................................................................................................19 

6.0 Observations ......................................................................................................................35 

7.0 Completeness, Accuracy, and Data Adequacy ..................................................................40 

7.1 Completeness of Data ............................................................................................40 

7.2 Technical Accuracy ...............................................................................................40 

7.3 Data Adequacy .......................................................................................................41 

7.4 Compliance with Regulations and Procedures ......................................................41 

8.0 References..........................................................................................................................42 

Attachment 1: Key Questions for NIOSH/ORAU Regarding Site Profile Documents ................43 

Attachment 2: Outstanding Records Requested of NIOSH to Support IAAP Site Profile 

Review ...................................................................................................................58 

Attachment 3: Conference Call with NIOSH and SC&A.............................................................60 

Attachment 4: IAAP Facility Site Expert Interviews ...................................................................61 

Attachment 5: Classified Review Agenda ....................................................................................86 

Attachment 6: Assessment of Dose Rates from “Generic Pit” .....................................................87 

Attachment 7: Jack Fix: Memorandum to File ............................................................................92 
Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

4 of 92 

ACRONYMS AND ABBREVIATIONS 

ABRWH Advisory Board on Radiation and Worker Health 

(also referred to as Advisory Board or Board) 

AEC Atomic Energy Commission 

AMAD Activity Median Aerodynamic Diameter 

BAECP Burlington Atomic Energy Commission Plant 

CFR Code of Federal Regulations 

DOE U.S. Department of Energy 

DOE-HQ U.S. Department of Energy Headquarters 

DU depleted uranium 

EEOICPA Energy Employees Occupational Illness Compensation Program Act 

EPA U.S. Environmental Protection Agency 

EU enriched uranium 

FS firing site 

g grams 

g/y grams per year 

g/cm2	 grams per square centimeter 

GM geometric mean 

GSD geometric standard deviation 

HE high explosive 

HEU highly enriched uranium 

HMX high melting explosives 

IAAP Iowa Army Ammunition Plant 

ICRP International Commission of Radiation Protection 

IFI in-flight-insertable 

IOP Iowa Ordnance Plant 

keV kiloelectron volts 

kg kilogram 

LANL Los Alamos National Laboratory 

LLNL Lawrence Livermore National Laboratory 

m meter 

m/s	 meters per second 

m3

/s	 cubic meters per second 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

5 of 92 

MDL minimum detectable level 

mg milligrams 

MIRD Medical Internal Radiation Dose 

mm millimeters 

mrad/h milliard per hour 

mrem/h millirem per hour 

mSv milliseiverts 

NCRP National Council on Radiation Protection 

NIOSH National Institute for Occupational Safety and Health 

NRC U.S. Nuclear Regulatory Commission 

NTA Eastman Kodak Nuclear Track Film Type A 

OCAS Office of Compensation Analysis and Support 

ORAU Oak Ridge Associated Universities 

PA posterioanterior 

ppm parts per million 

POC probability of causation 

PNNL Pacific Northwest National Laboratory 

PPE personnel protective equipment 

R&D research and development 

rem rem 

SEC Special Exposure Cohort 

SOP Standard Operating Procedure 

STAR Stability ARray 

TBD Technical Basis Document 

TEPC tissue equivalent photon counters 

TIB Technical Information Bulletin 

TLD thermoluminescent dosimeter 

μCi/y microcurie per year 

μg/m3 microgram per cubic meter 

μm micron or micrometer 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

6 of 92 

1.0 EXECUTIVE SUMMARY 

This final draft report by S. Cohen and Associates (SC&A, Inc.) is the integrated evaluation of 

the site profile, Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP), ORAUT-TKBS-0018, Revision 01 (ORAU 2005). Revision 01 of the 

Technical Basis Document (TBD) was issued on March 14, 2005, and incorporates major 

technical changes to the original TBD (i.e., Revision 00 (ORAU 2004)) that had been issued 

April 16, 2004. This review of the IAAP site profile combines two partial preliminary reports 

reviewing Rev. 01 of the TBD that SC&A submitted to the National Institute of Occupational 

Safety and Health (NIOSH) and the Advisory Board on Radiation and Worker Health (referred 

to as “Advisory Board” or “Board” in the present report) on April 18 and April 22, 2005 (SCATR-TASK1-0009 (SC&A 2005a) and SCA-TR-TASK1-0009b (SC&A 2005b), respectively). It 

also includes some new elements of the review that SC&A has added since that time based on 

comments on the preliminary reviews, as well as site expert interviews that have been 

declassified by the Department of Energy (DOE). 

SC&A prepared the two reports in response to a special request by the Advisory Board. SC&A 

began reviewing the IAAP site profile on March 17, 2005, three days after the revised TBD was 

issued. As contractor to the Board, SC&A’s directive was to review the TBD and assist the 

Board in evaluating the technical merit and credibility of the revised TBD as guidance for dose 

reconstructions for former IAAP workers. The urgency for SC&A to conduct this review was 

largely influenced by a Special Exposure Cohort (SEC) petition that was under review at that 

time by the Board and by NIOSH. Due to significant changes that had been incorporated in 

Revision 01 of the TBD, the Board concluded that an informed, fair, and final decision regarding 

the SEC petition would have to await a critical assessment of the revised TBD. During its April 

25–27, 2005, meeting in Cedar Rapids, Iowa, the Board voted to recommend that the SEC be 

granted to Atomic Energy Commission (AEC) workers employed at IAAP between 1949 and 

1975. The present combined review of the IAAP TBD was prepared in order to complete and 

finalize the preliminary and partial work that was done to support the Board’s requirements for 

its April 25–27 meeting. 

This review of the IAAP TBD was unprecedented in that it required that SC&A be allowed 

access to classified documents that contained data that NIOSH had used to develop the model for 

estimating external doses during 1949–1962 (the “generic pit” model). The generic pit model 

was constructed in order to protect classified data relating to the design of nuclear warheads that 

were assembled at IAAP during that period. For this review of the IAAP TBD, the need to 

assess classified information mandated significant changes to our standard review procedures. In 

past reviews of other TBDs, SC&A’s approach has been to engage a team of scientists where 

every member independently assessed the entire document before coming together for a critical 

open discussion. To accommodate the need for a review of classified material, two members of 

the SC&A team (and two Board members) with Q-clearances inspected classified documents that 

NIOSH had selected for use in its dose model. They prepared an analysis that was not reviewed 

by the rest of the team, but was submitted to DOE for declassification. The report was 

declassified in its entirety and was submitted to the Board (SC&A 2005b). The classified review 

itself, while critical to a broader understanding of key dose assessment models and assumptions, 

was constrained in a number of important ways. First, due to time limitations and the logistics of 

scheduling appropriately cleared SC&A, Advisory Board, and NIOSH personnel, the duration of 
Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

7 of 92 

the review was limited to 1.5 days. Second, SC&A was unable to conduct a wider survey of 

classified records pertinent to its TBD evaluation, but had to rely on what NIOSH had preselected for review instead. However, despite these constraints, the SC&A team was able to 

arrive at firm conclusions regarding the generic pit. 

In parallel with the classified review, which was focused on the validity of the generic pit model 

and on interviews with former IAAP workers with security clearances (these interviews were 

also submitted for declassification), the rest of the SC&A team conducted a broader review of 

the site profile, including the adequacy and accuracy of film badge data, the analysis of sources 

of internal dose, etc. This review of the TBD and associated unclassified material was presented 

in another partial report (SC&A 2005a). 

A conference call, in which the authors of the TBD, DOE staff, NIOSH staff, some Board 

members, and SC&A team members participated, provided clarification and information to 

SC&A on critical points. Furthermore, site expert interviews were also crucial in allowing 

SC&A to finalize this review. Attachment 1 lists the questions SC&A submitted to the Board 

and to NIOSH. Attachment 2 shows the list of documents that were requested by SC&A. 

Attachment 3 is reserved for the conference call transcript (not available at this time). 

Attachment 4 presents a summary of the site expert interviews. Attachment 5 contains the draft 

agenda for the April 12–13, 2005, review of classified records at DOE offices in Germantown, 

Maryland. Attachment 6 presents SC&A’s independent assessment of dose rates from external 

exposure to various hypothetical weapons components, modeled on the generic pit described in 

the TBD. Attachment 7 is a reproduction of a memo from Jack Fix of the Battelle Northwest 

Division regarding neutron dosimetry at IAAP. 

The SC&A review of the IAAP site profile was performed in accordance with Board-approved 

review procedures, which require that each site profile be evaluated against five measures of 

adequacy (also referred to as review criteria): (1) completeness of data sources, (2) technical 

accuracy, (3) adequacy of data, (4) site profile consistency, and (5) regulatory compliance. The 

SC&A review of the IAAP TBD determined that the degree to which the TBD satisfies the first 

three objectives and the last objective differs for different time periods of operation of the 

facility. SC&A has concerns in all four areas. In regards to consistency with other site profiles, 

the essential features of the IAAP site profile are unique among those reviewed by SC&A and 

therefore cannot be readily compared to the other profiles. 

Summary of Findings 

Finding 1: The external dose rate from the generic pit is likely to bound the external dose rates 

that may have been experienced by Line I workers from single pits at a distance of 1 meter prior 

to 1963. However, SC&A has concerns regarding the use of dose rates from the generic pit for 

worker dose reconstruction. 

Finding 2: SC&A has concerns and reservations about the “work factor” used to derive annual 

external doses prior to 1963. As a result, there are serious questions as to whether the workfactor calculation method is scientifically valid and claimant favorable. Furthermore, the work 

factor may not address pre-1963 doses to non-Line I radiation workers, such as security guards 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

8 of 92 

and other personnel who entered storage areas. In addition, it may not capture doses due to 

incidents. 

Finding 3: The reconstruction of external doses in the pre-1963 period uses a bounding estimate 

based on the calculated dose rates from a bare, generic pit, while the external doses in the 1963– 

1974 period are based on film badge dosimetry records and other data. The generic pit model 

was constructed because of the paucity of film badge records during these early years of 

operation, and because national security considerations prevent NIOSH from revealing the 

details of the actual weapons assemblies that were handled at IAAP. The generic pit was 

therefore designed to be a bounding, claimant-favorable model that is not based on classified 

data. However, it is also not based on a valid scientific analysis of the actual conditions of 

radiation exposure during that time period. The result is a sharp discontinuity between the 

external doses estimated for that period and for the 1963–1974 period, because the external dose 

assessments for these two periods use very different methodologies. The inconsistent methods of 

dose reconstruction for these two periods could result in an inequitable resolution of claims from 

workers exposed during these two periods. 

Finding 4: The statistical significance or representativeness of annual dose distributions for 

1963–1967 (Table 6.4 of TBD) is not clearly established, since only a limited number of 

radiation workers were monitored prior to 1968. Furthermore, missed doses due to the erratic 

use of film badges cannot be estimated. This problem is compounded by the paucity of data for 

reliably assigning monitored workers to radiological job categories. 

Finding 5: It may not be possible to accurately determine external doses from Am-241, due to 

the low sensitivity of the film badges to the low-energy photons emitted by this radionuclide. 

Finding 6: Film badges worn on the lapel or collar may not accurately represent organ doses. 

Therefore, adjustment factors are needed, at least for some groups of workers. 

Finding 7: NIOSH did not consider all significant sources of data and information relevant to 

dose reconstruction. In general, there is an over-reliance on theoretical modeling for purposes of 

deriving upper-bound estimates at the expense of identifying and applying available radiological 

and operational information to achieve “a substantial basis of fact,” as stipulated in 42 CFR 82. 

Finding 8: SC&A’s classified review substantiated the basis for the use of the 1993–2003 

Pantex neutron-to-photon ratios as a claimant-favorable surrogate for IAAP neutron dose 

estimates. However, workers whom we interviewed said that neutron dose rate and spectral 

measurements had been taken at IAAP by a DOE laboratory. The lack of a review of actual 

IAAP data raises concerns both about the accuracy and reasonableness of the neutron-to-photon 

ratio proposed in the TBD and about the completeness of NIOSH’s document research. 

Finding 9: External dose estimates for unmonitored workers are claimant favorable for nonradiological workers. However, they are not scientifically valid nor claimant favorable for 

unmonitored workers who were frequently in the proximity of radioactive materials. 
Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

9 of 92 

Finding 10: The radon concentrations presented in the TBD are not scientifically valid or 

claimant favorable, due partly to a scientifically incorrect choice of data from Pantex in Texas 

for use in Iowa, which has much higher radon levels than Texas. 

Finding 11: Assumptions about worker exposures to medical x-rays are not uniformly claimant 

favorable. 

Finding 12: Tritium exposure estimates are exceedingly claimant favorable, but some of the 

assumptions that yield the higher dose estimates are not scientifically valid. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

10 of 92 

2.0 SCOPE AND INTRODUCTION 

Under the Energy Employees Occupational Illness Compensation Program Act (EEOICPA or 

the Act) and Federal regulations defined in Title 42, Code of Federal Regulations, Part 82, 

Methods for Radiation Dose Reconstruction Under the Energy Employees Occupational Illness 

Compensation Program (42 CFR 82), the Advisory Board is mandated to conduct an 

independent review of the methods and procedures used by NIOSH and its contractors for dose 

reconstruction. As contractor to the Advisory Board, SC&A has been charged under Task 1 to 

support the Advisory Board in this effort by independently evaluating a select number of site 

profiles that correspond to specific facilities at which energy employees worked and were 

exposed to ionizing radiation. 

The present review of Technical Basis Document for Atomic Energy Operations at the Iowa 

Army Ammunition Plant (IAAP), ORAUT-TKBS-0018, Revision 01 (ORAU 2005), is part of the 

series of site profile reviews prepared to support the Advisory Board’s deliberations. SC&A 

critically evaluated this site profile in order to: 

• Determine the completeness of the information gathered by NIOSH in preparing the site 

profile, with a view to assessing the adequacy and accuracy of these data to support dose 

reconstruction 

• Assess the technical merit of the data and information 

• Assess NIOSH’s use of the data in dose reconstructions 

The IAAP began operations in 1941, primarily to develop, use, and test a wide variety of 

ordnance items. In the late 1940s, IAAP began research, development, and fabrication of high 

explosive (HE) ordnance related to the development, testing, maintenance, retrofits, assembly, 

and disassembly of nuclear weapons. It appears that the first nuclear weapon assembly operation 

began in March 1949 with the Mark IV pit.1 However, based on a review of the TBD and its 

supporting documentation, there appears to be some uncertainty as to when fissile material was 

first introduced onsite―it could have been as early as 1949 or as late as 1955. The uncertainty 

appears to be related to whether the activities at the site related to the weapons program from 

1949 until 1955 were limited to the non-nuclear components of weapons, or whether fissile and 

other radioactive materials were handled at the facility during this time period. According to the 

TBD, the components of the weapons handled at IAAP prior to 1955 appear to have been limited 

to non-fissile material, such as the tamper, which is the hollow sphere consisting of high 

explosives. The fissile material, consisting of a second hollow sphere of highly enriched 

uranium or weapons grade plutonium, was inserted into the tamper. Prior to 1955, in order to 

preclude an accidental nuclear detonation, the pits were not inserted into the tamper until the 

weapons were assembled in flight. For this reason, weapons of this design were referred to as inflight-insertable (IFI) weapons. NIOSH believes that, though HE related to weapons assembly 

were handled at IAAP prior to 1955, fissile material was not actually handled onsite until 1955, 

because the weapons assembled at IAAP were of the IFI design. The TBD cites literature in 

support of this hypothesis. Nevertheless, in order to give the benefit of the doubt to the 

claimants, NIOSH decided to develop the TBD on the conservative assumption that there were 

1

 The term “pit” is used in the TBD and its supporting documentation to refer to the hollow sphere of 

plutonium or uranium that comprised the core of the devices. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

11 of 92 

fissile materials on site beginning in 1949, when nuclear weapons assembly work started at 

IAAP. SC&A concurs with this decision. 

Beginning in 1955, the primary activities at the facility involving HE and fissile material 

included the assembly and testing2

 of complete weapons. These are collectively referred to as 

Line I operations. At that time, a radiological monitoring program was initiated consisting of the 

issuance of film badges to some workers, radiological surveys, continuous air monitoring, and 

specialized training for weapons assembly workers. In 1963, the film badges were exchanged on 

a biweekly schedule. In 1964, the exchange frequency was reduced to once every 4 weeks. 

Monitoring of internal exposures began in 1962. 

From the perspective of historical dose reconstruction, based on the availability of relevant 

radiological monitoring data, it is convenient to divide the operations at IAAP into three time 

periods, as follows: 

(1) 1949–1955: No radiological monitoring data upon which to base dose reconstructions 

(there is reason to believe that there was no fissile material onsite during these years) 

(2) 1955–1962: Only limited radiological monitoring data available for use in dose 

reconstruction 

(3) 1963–1974: A steady increase in available radiological monitoring data in terms of the 

number of dosimeter readings; however, the number of monitored workers grew slowly 

and many workers exposed to significant levels of radiations were never issued badges 

The TBD distinguishes these three time periods because of the differences in the radiological 

monitoring data available for dose reconstruction. In addition, all of the data and supporting 

documentation provided in the TBD for dose reconstruction in the post-1962 time period are 

based on unclassified or declassified data, while a large portion of the data and descriptions of 

operations used by NIOSH to support dose reconstruction for the time period prior to 1963 are 

based on classified information. 

In accordance with directives provided by the Advisory Board and compliance with Boardapproved review procedures prepared by SC&A, this report is organized into the following 

sections: 

1.0 Executive Summary 

2.0 Scope and Introduction 

3.0 Assessment Criteria, Method, and Chronology for Review 

4.0 Site Profile Strengths 

5.0 Findings 

6.0 Observations 

7.0 Completeness, Adequacy, Technical Accuracy, and Regulatory Compliance 

2

 The term “testing” is used here to refer to experiments and simulated testing of mock pits, not the actual 

detonation of nuclear weapons. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

12 of 92 

3.0 ASSESSMENT CRITERIA AND METHODS 

Under Task 1, SC&A is charged with evaluating the approach set forth in a limited number of 

site profiles used by NIOSH for dose reconstruction. These documents are reviewed for their 

completeness, technical accuracy, adequacy of data, consistency with other site profiles, and 

compliance with the stated objectives, as defined in SC&A Standard Operating Procedure for 

Performing Site Profile Reviews (SC&A 2004b). The present review is specific to the IAAP site 

profile and supporting documents, though some of its elements may also apply to other site 

profiles. 

3.1 OBJECTIVES 

3.1.1 Objective 1: Completeness of Data Sources 

SC&A reviewed the site profile with respect to Objective 1, which requires an identification of 

principal sources of data and information that are applicable to the development of the site 

profile. The two elements examined under this objective include (1) determining if the site 

profile made proper use of available data that is relevant and significant to dose reconstruction, 

and (2) investigating whether other relevant and significant sources are available but were not 

used in the development of the site profile. For example, if relevant data were discovered that 

the TBD has not taken into consideration, this would constitute a completeness-of-data 

deficiency. The Oak Ridge Associated Universities (ORAU) site profile document database and 

the references cited in the TBD were evaluated to determine the completeness of data collected 

by NIOSH in the development of the site profile. 

3.1.2 Objective 2: Technical Accuracy 

Under Objective 2, SC&A is required to perform a critical assessment of the methods used in the 

site profile to develop technically defensible guidance or instruction. This includes an evaluation 

of field characterization data, source-term data, technical reports, standards and guidance 

documents, and literature related to processes that occurred at IAAP. The goal of this objective 

is to evaluate whether the technical approach used by NIOSH in the interpretation and analysis 

of data is scientifically sound and takes appropriate account of uncertainties. 

3.1.3 Objective 3: Adequacy of Data 

For Objective 3, SC&A is required to determine whether the data and guidance presented in the 

site profile are sufficiently detailed and complete to conduct dose reconstruction, and whether a 

defensible approach has been developed when there are insufficient data. In addition, this 

objective requires SC&A to assess the credibility of the data used for dose reconstruction. Here, 

the intent is to identify gaps in the facility data that may influence the outcome of the dose 

reconstruction process. For example, data would be considered inadequate if a group of workers 

had the potential to be exposed to neutrons, but were not monitored for neutron exposure. In 

addition, SC&A would also assess the approach that NIOSH uses to estimate missed doses. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

13 of 92 

3.1.4 Objective 4: Consistency Among Site Profiles 

This objective requires SC&A to identify common elements among site profiles completed or 

reviewed to date, as appropriate. SC&A determined that the IAAP TBD (ORAU 2005) is unique 

among those reviewed so far. It addresses early operational and record-keeping deficiencies in a 

way that is different from other Atomic Weapons Employers in that a generic pit and a work 

factor were devised to estimate external doses during the early years of operation. These 

elements are not present in any of the other site profiles reviewed by SC&A. The hypothetical 

model of the generic pit, coupled to the work factor, which was introduced in order to protect 

classified weapons design data, is also unique to the IAAP site profile among those reviewed so 

far. In the case of the film badge data, the IAAP TBD is the only one reviewed so far where 

there were systematic missed doses among monitored workers due to the erratic wearing of film 

badges. Issues relating to pit storage and exposure geometry have also not occurred in other site 

profiles reviewed so far. Hence no assessment of consistency with other site profiles was done 

in this report. A consistency check will be made with Pantex if the Board asks SC&A to review 

the profile of that site. 

3.1.5 Objective 5: Regulatory Compliance 

Objective 5 requires SC&A to evaluate the degree to which the site profile complies with stated 

policy and directives contained in 42 CFR 82. In addition, SC&A evaluated the TBD for 

adherence to general quality assurance policies and procedures utilized for the performance of 

dose reconstructions. 

In order to place the above objectives into the proper context as they pertain to the site profile, it 

is important to briefly review key elements of the dose reconstruction process, as specified in 

42 CFR 82. Federal regulations specify that a dose reconstruction can be broadly placed into one 

of three discrete categories. These three categories differ greatly in terms of their need for 

accuracy and completeness of dose data, as explained below. 

Category 1. Least challenged by any deficiencies in available dose and monitoring data are dose 

reconstructions that are aimed at developing a minimum dose estimate. In such cases even a 

partial assessment (or minimized doses) corresponds to a probability of causation (POC) value in 

excess of 50%, and assures compensability of the claim. Such partial or incomplete dose 

reconstructions with a POC > 50% may, in some cases, involve only a limited amount of 

external or internal exposure data. In extreme cases, even a total absence of a positive 

measurement may suffice for an assigned organ dose that results in a POC > 50%. For this 

reason, dose reconstructions in behalf of this category may only be marginally affected by 

incomplete or missing data, or uncertainty in the measurements. In fact, regulatory guidelines 

recommend the use of a partial or incomplete dose reconstruction, the minimization of dose, and 

the exclusion of uncertainty for reasons of process efficiency, as long as this limited effort 

produces a POC of ≥ 50%. 

Category 2. A second category of dose reconstruction is defined by Federal guidance, which 

recommends the use of worst-case assumptions. The purpose of worst-case assumptions in dose 

reconstruction is to derive maximal or highly improbable dose assignments. For example, a 

worst-case assumption may place a worker at a given work location 24 hours per day, 365 days 

per year. The use of such maximized (or upper-bound) values, however, is limited to those 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

14 of 92 

instances where the resultant maximized doses yield POC values below 50%, in which case the 

claimants are not compensated. For this second category, the dose reconstructor needs only 

ensure that all potential internal and external exposure pathways have been considered. 

As was the case with minimum doses, the benefit of worst-case assumptions and the use of 

maximized doses in dose reconstruction is efficiency. Efficiency is again achieved by the fact 

that maximized doses avoid the need for precise data and eliminate the need for consideration of 

the uncertainty of the dose. Lastly, the use of bounding values in dose reconstruction minimizes 

any controversy regarding the decision to deny a claim. 

To satisfy this type of a dose reconstruction, the TBD must, at a minimum, provide information 

and data that clearly identify (1) all potential radionuclides, (2) all potential modes of exposure, 

and (3) upper limits for each contaminant and mode of exposure. Thus, for external exposures, 

maximum dose rates must be identified in time and space that correspond to a worker’s 

employment period and work locations; similarly, in order to maximize internal exposures, 

highest air concentrations and surface contaminations must be identified. 

Category 3. The most complex and challenging dose reconstruction represents cases where the 

case cannot be dealt with under one of the two categories above. For instance, when a minimum 

dose estimate does not result in compensation, a next step is required to make a more complete 

estimate. Or when a worst-case dose estimate that involves assumptions that may be highly 

unrealistic results in a POC greater than 50%, compensation is not necessarily justified. A more 

refined estimate may be required either to deny or to compensate. In dose reconstructions that 

may be represented as “reasonable,” NIOSH has committed to resolve uncertainties in favor of 

the claimant. According to 42 CFR 82, NIOSH interprets “reasonable estimates” of radiation 

dose as follows: 

. . . estimates calculated using a substantial basis of fact and the application of 

science-based, logical assumptions to supplement or interpret the factual basis. 

Claimants will in no case be harmed by any level of uncertainty involved in 

their claims, since assumptions applied by NIOSH will consistently give the 

benefit of the doubt to claimants. [Emphasis added.] 

In order to achieve the objectives described above, SC&A reviewed each of the six sections of 

the site profile, their supplemental attachments, supporting documentation, and selected 

classified records. The main goal of the evaluation was to assess the ability of the site profile to 

support the three aforementioned categories of dose reconstructions. In addition, SC&A 

interviewed a number of former IAAP workers and site experts. The following briefly describes 

major sections of the site profile and our method of review. 

Section 1 of the TBD provides a brief introduction. Though not explicitly addressed in the 

introduction, it is appropriate to acknowledge the fact that neither the Act nor 42 CFR 82, which 

implements the Act, requires a site profile. Site profiles were developed by NIOSH as a resource 

available to dose reconstructors. Furthermore, SC&A understands that site profiles are living 

documents, which may be revised, refined, and supplemented with technical information 

bulletins (TIBs), as required, to help dose reconstructors. Site profiles are not intended to be 

prescriptive or necessarily complete in terms of addressing every possible issue that may be 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

15 of 92 

relevant to any given dose reconstruction. SC&A kept these limitations in mind when evaluating 

the TBD. 

Section 2 describes the site and the facility, the operational history, and the processes. This is an 

extremely important part of the site profile, because these descriptions and the supporting data 

serve as the underpinning for subsequent sections. This section, along with the appendices to the 

TBD, describes the facilities and processes that are relevant to dose reconstruction. Our review 

of this section examines whether all the potentially important site activities and processes are 

adequately described, and whether the characterization of the source terms is sufficient to 

support dose reconstruction. This review was particularly challenging, because much of the data 

relevant to dose reconstruction for time periods prior to 1963 are classified. 

Section 3 provides a set of procedures for reconstructing workers’ exposures to medical x-rays 

that were required for employment at the facility. SC&A reviewed this section for technical 

adequacy and claimant favorability. 

Section 4 of the site profile provides background information and guidance to dose 

reconstructors for estimating environmental doses to unmonitored workers outside of the 

facilities during working hours. Environmental exposures may be the result of routine and 

episodic airborne emissions from the facility. SC&A reviewed this section from the perspective 

of the source terms and the atmospheric transport, deposition, and resuspension models used to 

derive estimates of external and internal exposures. 

Section 5 presents background information and guidance to dose reconstructors for deriving 

occupational internal doses to workers. This section was reviewed with respect to background 

information and guidance regarding (1) the types, mixes, and chemical forms of the 

radionuclides that workers may have inhaled or ingested; (2) the recommended assumptions for 

use in reconstructing internal doses (based on models, whole-body counts, and bioassay data, 

when available); (3) the methods recommended for use in the reconstruction of missed internal 

dose; and (4) the methods for characterizing uncertainty in reconstructed internal doses. 

Section 6 presents background information and data used for deriving occupational external 

doses to workers. This is by far the most critical section of the TBD and was given the greatest 

attention in our review. This section was reviewed for the quality and completeness of the 

technical information, the assumptions pertaining to exposure scenarios, and the energy 

distribution of external radiation to which workers may have been exposed. SC&A also 

reviewed the approach in the TBD for converting external dosimetry data to organ-specific 

doses, the methods for the reconstruction of missed external doses, and the characterization of 

uncertainty in the reconstructed external doses. 

3.2 A CHRONOLOGY OF EVENTS 

3.2.1 Overall Review 

Our review began on March 17, 2005, with an initial evaluation of the TBD. SC&A then 

developed a list of questions that was transmitted to the Board and NIOSH in two memos dated 

March 22 and March 31, 2005 (see Attachment 1). A list of both classified and unclassified 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

16 of 92 

documents and records was submitted to NIOSH in a letter dated April 11, 2005, requesting 

assistance in obtaining access to these documents (see Attachment 2). After a more detailed 

review of the TBD and its unclassified supporting documentation, a factual-accuracy conference 

call was held with members of the Advisory Board and NIOSH on April 8, 2005. This 

conference call was recorded and transcribed. On April 12 and 13, 2005, two SC&A team 

members with Q-clearances, joined by two Board members, visited the Department of Energy 

(DOE) offices in Germantown, Maryland, where the classified documents used by NIOSH in 

preparing the TBD are stored. On April 13, 2005, a second conference call was held with the 

Advisory Board and NIOSH. The purpose of this call was two-fold: to continue our factualaccuracy review and to discuss our initial findings. This conference call was also recorded and 

transcribed (see Attachment 3). In addition, SC&A conducted interviews with site experts (see 

Attachment 4). 

3.2.2 Classified Review, April 12–13, 2005 

Two SC&A team members, along with two members of the Advisory Board, participated in a 

review of some of the classified information that NIOSH utilized in preparing the TBD. This 

review was conducted in conjunction with NIOSH staff over a one and one-half-day period 

(April 12–13, 2005) in a secure facility at the DOE headquarters building in Germantown, 

Maryland. The documents that were reviewed were selected by NIOSH and included the 

following: 

• IAAP History Reports (NARA)—classified 

• Health Physics Analysis of Doses Received at the Iowa Ordinance Plant, PNNL-ETD0385 (PNNL)—classified 

• Annual Weapons Program Report, Volume 2—Retired Weapons (DOE-HQ)—classified 

• University of Iowa records (selected dosimetry information) 

• DOE incident reports (selected) 

• Pantex tritium and depleted uranium (DU) monitoring data 

• Agency for Toxic Substances and Disease Registry health consultation 

• Oak Ridge National Laboratory—Indoor Radiological Survey 

A draft agenda for the classified review session is provided as Attachment 5. 
 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

17 of 92 

4.0 SITE PROFILE STRENGTHS 

In developing a TBD, the assumptions used must be fair, consistent, and scientifically robust, 

and uncertainties and inadequacies in source data must be explicitly addressed. The 

development of the TBD must also consider efficiency in the process of analysis of individual 

exposure histories, such that claims can be processed in a timely manner. With this perspective 

in mind, there were a number of strengths identified in the IAAP TBD (ORAU 2005). 

For the cases where film badge readings are reported as below the limits of detection, NIOSH 

recommends the guidance in OCAS-IG-001 (NIOSH 2000), which is to assume a lognormal 

distribution with a geometric mean (GM) of one-half the lower limit of detection and a geometric 

standard deviation (GSD) of 1.52. This approach is scientifically valid and claimant favorable. 

However, NIOSH should explain how adjustments to doses recorded by the film badges would 

be made in such cases, and how other adjustment factors, including estimates of neutron 

exposure, are accounted for in this process. 

NIOSH makes a concerted effort to place an upper bound on many exposure scenarios that may 

have occurred at the IAAP. Many of these scenarios were unique to IAAP, including 

occupational and environmental exposures to tritium and some aspects of exposure to DU. 

These scenarios include the following: 

• Venting tritium containers 

• Burning explosives containing residual DU 

• Hydroshots, which involved blowing up simulated pits made of DU 

• Machining baratols, which were the explosives surrounding the DU ball 

In assessing internal exposures to DU, NIOSH recommends assuming either Lung Clearance 

Type M or S, depending on the organ of concern, in order to ensure that the claimant is given the 

benefit of the doubt. Some other aspects of the estimation of internal exposure to DU are also 

scientifically defensible and claimant favorable. For instance, the TBD assumes that drinking 

water for the site was obtained from nearby Mathes Lake, which could have been contaminated 

by runoff of uranium associated with hydroshots. This assumption is made despite the fact that 

the levels of uranium found in the lake are consistent with typical background levels. 

Assuming that the water samples cited in the TBD are representative of all years of facility 

operation, the approach recommended in the TBD to address drinking water exposures from DU 

in runoff is scientifically valid and claimant favorable. 

A third example of a TBD strength in relation to DU concerns the modeling of the DU that was 

released during the burning of explosives. Based on information cited in the literature, NIOSH 

estimates that 2,000 g/y of DU was burned along with high explosives in the Explosive Disposal 

Area. The TBD reports that the burning of DU was frequent; hence it is appropriate to model 

atmospheric dispersion using standard Gaussian dispersion models for ground-level releases.3 

3

 In general, even if releases are intermittent rather than continuous, it is appropriate to use average annual 

dispersion coefficients for deriving annual doses, as long as the releases are frequent (e.g., at least once a week) and 

randomly distributed. The reason this approach is acceptable is that the variation in meteorological conditions will 

average out over the course of a year, resulting in annual exposures that are not very different than if the releases 

were in fact uniform and continuous. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

18 of 92 

NIOSH assumes that all of the DU is aerosolized. Atmospheric dispersion factors are listed for 

100 m, 500 m, and 1,000 m. The dose reconstructor is instructed to use the distance that is most 

appropriate and claimant favorable for individual dose reconstructions. The model assumes a 

wind speed of 2 m/s that blows toward the receptor 25% of the time. In addition, no credit is 

taken for lofting of the plume caused by the heat of the fire. On the premise that the source term, 

event frequency, and assigned distances are correct and/or conservative,4

 resultant doses are 

likely to be scientifically valid and claimant favorable. 

NIOSH’s adoption of a neutron-to-photon ratio with a GM of 0.79 and a GSD of 1.57 appears to 

be claimant favorable in light of the empirical data and Monte Carlo simulations, which indicate 

that the true neutron-to-photon ratios were likely to be lower by perhaps a factor of 2. However, 

as noted later in this report, this approach ignores actual neutron dose rate and spectral 

measurements performed at IAAP. 

The assessment of environmental tritium doses is also claimant favorable. Based on effluent 

data gathered at the site from 1965 through 1970, NIOSH assumes a maximum annual release of 

26,000 μCi/y of tritiated water. NIOSH further assumes that the release is diluted in a plant 

stack vent flow rate of 0.3 m3

/s, with no credit taken for atmospheric dispersion between the 

release point and the receptor location, and that the wind blows in the direction of the receptor 

25% of the time. This approach is commonly described as an NCRP Level 1 screening analysis, 

which is considered highly conservative, since no credit is taken for atmospheric dispersion. 

Applying the maximum annual tritium source term to all years of operation is highly claimant 

favorable. 

4

 SC&A did not verify these parameters. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

19 of 92 

5.0 FINDINGS 

Finding 1: The external dose rate from the generic pit is likely to bound the external dose 

rates that may have been experienced by Line I workers from single pits at a distance of 

1 meter prior to 1963. However, SC&A has concerns regarding the use of dose rates from the 

generic pit for worker dose reconstruction. 

Since NIOSH concluded that (1) film badge data for the period 1949–1962 were too sparse for 

dose reconstruction, and (2) radiation fields from actual pits handled during that period could not 

be used because the data are classified, NIOSH created a novel approach to lay the basis for dose 

estimation. The creation of a hypothetical “generic pit” that would have a dose rate higher than 

any actual pit handled at IAAP was central to this approach. A limited number of NIOSH 

personnel (with Q-clearance) conducted a review of relevant classified documents, which 

characterized pits and weapon assemblies handled at IAAP prior to 1963. Based on this 

information, NIOSH constructed a generic pit that would result in an overestimate of the dose 

rates from the actual weapons. The mass of plutonium was chosen because it is approximately 

the mass in the Trinity nuclear device and the Nagasaki bomb. The diameter was chosen to 

result in a thin spherical shell, which minimizes self-absorption and thus maximizes the dose 

rate. 

The following describes our understanding of the dose reconstruction approach adopted in the 

TBD (ORAU 2005) for Line I workers prior to 1963. Line I workers were exposed to external 

radiation mainly because they physically handled pits. Based on a listing of the weapons 

provided in Appendix B of the TBD, it is clear that a large variety of devices were assembled, 

disassembled, refurbished, and/or maintained by these workers. 

Evidence in support of NIOSH’s claim that the generic pit has a dose rate greater than those 

handled at IAAP in the pre-1963 period could not be disclosed publicly because it involved 

classified data about the characteristics of the pits that were handled before 1963. It was, 

therefore, not included in the TBD. In a compromise that balances national security against the 

need for transparency in dose reconstruction, NIOSH granted access to these classified 

documents to two members of SC&A and two Board members, all with Q-clearances. This 

partial access obtained by the audit team and the Board allowed some independent review of 

NIOSH’s claim that the dose rate from the generic pit was higher than any actual pit handled at 

IAAP prior to 1963. Hence, while the documentary basis of NIOSH’s claim could not be made 

public because of national security considerations, the Board and its contractor, SC&A, could 

provide assurance to the public that they had reviewed the materials independently to verify 

NIOSH’s claim about the generic pit dose rate, as well as other classified issues relating to the 

dose reconstruction in the pre-1963 period. 

The review of the classified material considered relevant assumptions and parameters as 

provided in classified documentation, primarily Health Physics Analysis of Dose Received at the 

Iowa Ordnance Plant (PNNL-ETD-0385, Traub et al. 2005), including mass, radioactive 

components, pit geometry, cladding, isotopic composition, and radioactive impurities. Based on 

an examination of the documents made available by NIOSH and the classified discussion that 

took place, the SC&A team’s Q-cleared members concurred with NIOSH’s conclusion that the 

generic pit dose rate exceeded the dose rate of all pits handled at IAAP. SC&A cautions that this 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

20 of 92 

conclusion was based on a partial examination of the documents, because not all requested 

documents were available. However, the available documentation, as well as the frank classified 

discussion, led the SC&A team members to have a high degree of confidence that NIOSH is 

correct in claiming that the generic pit dose rate is higher than any of the pits handled at IAAP 

(as per the list in the TBD). 

SC&A independently calculated dose rates from a generic pit modeled after the description in 

Appendix D of the TBD (see Attachment 6). Using a more sophisticated model that employed 

an anthropomorphic phantom, we found that the dose rate at 1 m from a plutonium pit with an 

isotopic composition based on a reported composition of weapons-grade plutonium was 

somewhat higher (48 vs. 33 mrem/h) than the dose rate reported in the TBD. We believe the 

difference is primarily attributable to different assumptions about the isotopic composition. 

However, we found that if the worker was in more intimate contact with the pit, the rate 

increased to 135 mrem/h. 

There are many other issues in the actual calculation of a scientifically valid dose. Therefore, a 

claimant-favorable dose rate at a distance of 1 m does not necessarily assure a dose 

reconstruction that is claimant favorable. Moreover, as discussed in Section 7.4, the introduction 

of a hypothetical construct (i.e., the generic pit model), due to the legitimate need to protect 

classified data on weapons design, raises issues of regulatory compliance in dose reconstruction. 

SC&A also has other concerns regarding the use of the overall generic pit approach for dose 

reconstructions. These are discussed in Finding 2. 

Finding 2: SC&A has concerns and reservations about the “work factor” used to derive 

annual external doses prior to 1963. As a result, there are serious questions as to whether the 

work-factor calculation method is scientifically valid and claimant favorable. Furthermore, 

the work factor may not address pre-1963 doses to non-Line I radiation workers, such as 

security guards and other personnel who entered storage areas. In addition, it may not 

capture doses due to incidents. 

NIOSH developed the work factor to represent the effective exposure duration of pre-1963 

workers to the generic pit. NIOSH divided the entire period of operation of the IAAP into four 

eras. The work factor is based on film badge data from Era 3, spanning the years 1962–1967, 

and Era 4, from 1968–1974. The film badge data were compared to calculated dose rates from 

actual pits handled in each of these two eras. The effective exposure duration for each year in 

each era was computed as follows: 

• NIOSH calculated the hourly dose rate at a distance of 1 m from each pit that was 

handled from 1962 to 1974. These calculations were based on classified data on these 

pits and could not be independently verified by SC&A. 

• Weighted average dose rates were calculated for Era 3 and for Era 4, based on the pits 

handled during these two eras, yielding era dose rates of 1.08 and 1.48 mrem/h, 

respectively (see Table 6.5 of the TBD). 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

21 of 92 

• A hypothetical annual dose for each era was calculated by multiplying the appropriate era 

dose rate by an assumed work year of 2,000 hours. This estimated annual dose 

(2,160 mrem for Era 3 and 2,960 mrem for Era 4, as listed in Table 6.5 of the TBD) is the 

dose to a hypothetical individual located at a distance of 1 m from a pit for 2,000 hours. 

• The actual annual dose received by workers during each year from 1962 to 1974 was 

calculated from the GM of the non-zero film badge dosimeter readings for that year, 

modified for Hp(10). 

• The work factor for a given year is the ratio of the actual annual Hp(10) dose to the era 

dose. 

• NIOSH calculated the GM and GSD of the work factors for the period 1962–1974. 

• To calculate the external annual dose to workers for each of the years 1949–1962, 

NIOSH first determined the hourly dose rate 1 m from the generic pit, using the MCNP 

code. 

• Based on the calculated photon spectra and the known energy response characteristics of 

the film badge dosimeters used at IAAP, NIOSH then determined the hourly dose rate 

that would have been recorded by these dosimeters. 

• Finally, NIOSH calculated an estimated annual dose rate for each year by multiplying 

this adjusted hourly dose rate, corrected for the ingrowth of Am-241, by the assumed 

work-year of 2,000 hours. 

SC&A has the following scientific concerns about the work factor: 

• The non-zero film badge data for 1962–1974 exclude missed doses that have not been 

evaluated and cannot be evaluated based on the data in the TBD. Considerable work and 

investigation is likely to be required to determine whether scientifically and statistically 

valid estimates of this component of missed dose can be estimated. 

• There are several reasons why workers' exposures to the weapons handled in the 1949– 

1962 period may not have been comparable to the exposures of workers in 1962–1974 

period. First, formal work practices may have been different. Second, the production 

activities themselves may have been different. Finally, earlier handling and working of 

weapons assembly and disassembly may have differed from the later periods, simply on 

account of less experience in the earlier period, necessitating more contact with or work 

near the pits. Hence the exposure duration and geometry may well have been different. 

• A typical workweek at IAAP was 40–50 hours. Since the late 1950s was a period of 

heavy production of nuclear weapons, the working hours may have been longer during 

that time than during Eras 3 and 4, on which the work factor was based. Hence, the 

comparison of Eras 1 and 2 to Eras 3 and 4 may not be valid. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

22 of 92 

• NIOSH implicitly assumed that the radiation field experienced by the workers could be 

scaled to the radiation field at 1 m from each of the real pits handled during the entire 

period of operation. The relative contribution of the external radiation from a single pit 

to the total radiation field may have been different in the 1949–1962 and 1962–1974 eras. 

In that case, the work factor methodology would be invalid. 

There are also some statistical issues associated with the estimate apart from the question of 

missed dose in the non-zero film badge readings: 

• The use of a lognormal distribution of work factors is not claimant favorable for 

estimating individual doses. Use of such a distribution assumes that the distribution 

characterizes, in a claimant-favorable way, the experience of an individual worker, whose 

specific tasks and doses over the years may be different than those of others whose data 

are in the same pool. SC&A has suggested in a separate report to the Board and to 

NIOSH that the use of fixed, 95th percentile values are more claimant favorable in most 

cases than the use of the entire lognormal distribution. 

• The post-1962 doses need correction factors for each organ, notably those in the pelvic 

area. This indicates that a work factor may need to be estimated for each organ, creating 

new uncertainties. 

Additional questions about the validity of the work factor arise from site expert interviews. 

SC&A was not able to confirm the basic assumptions behind this calculation from the data that 

were made available during the classified review process or from unclassified data. These 

assumptions are that the proximity of the worker to the individual pit and the duration of 

exposure to each pit were the same during the 1949–1962 and the 1962–1974 time periods. 

Most important, as stated earlier, NIOSH assumed that the radiation field experienced by the 

workers during these two time periods could be scaled to the radiation field at 1 m from each of 

the real pits handled during the entire period of operation. 

SC&A has not been able to corroborate these assumptions by the limited interviews with former 

production line workers. Attachment 4 contains a summary of the collective experience of 

approximately a dozen IAAP production, production control, security, and safety workers, as 

recounted in the interviews. In fact, workers recounted instances where they were exposed to 

more than one pit during routine operations (e.g., assembly, disassembly, and inspection) and in 

storage areas (e.g., security guards). 

With respect to the guards, who were not monitored for radiation exposure, former workers 

indicated that the area radiation measurements recorded for the pit storage areas were among the 

highest at IAAP (in various Yard C pit storage areas, annual area readings of 18.2, 16.9, 14.6, 

11.7, and 7.8 rem were recorded by photon monitors, for an average of 1–2 mrem/h), and the 

distances between the guards’ locations and the pit arrays were actually smaller than that 

between the pits and the area monitors, making an even higher dose rate likely for the guards, 

assuming no intervening shielding. This may invalidate the assumption in the TBD that, for dose 

assessment purposes, guards can be treated the same as line production workers. The radiation 

exposures of the security guards need to be evaluated further by NIOSH. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

23 of 92 

The time individual workers were in the immediate proximity of the pit (i.e., within 1 m) 

apparently varied with the specific program, the skill of the particular worker, the quality 

assurance process required, and the number of units processed per day. It is unclear how the GM 

work factor of 0.153, which equates to 1.22 hours per 8-hour day at 1 m from the pit, can be 

reconciled with the accounts of the former workers. Such a low work factor also does not take 

into account the considerable direct contact during specific work processes, which would 

increase overall dose, particularly to the torso (which necessitated lead aprons in similar 

operations at Pantex) and to extremities.5

 Finally, there may have been significant differences in 

incidents in the pre-1963 period and those occurring in the 1962–1974 period. It therefore 

appears that a work factor deriving from the later period may not reflect the frequency or 

radiological conditions that may have typified earlier incidents. 

For the above reasons, SC&A concludes that: 

• The work factor is of questionable scientific and statistical validity. 

• The use of the work factor would not result in dose estimates that are demonstrably 

claimant favorable. 

Finding 3: The reconstruction of external doses in the pre-1963 period uses a bounding 

estimate based on the calculated dose rates from a bare, generic pit, while the external doses in 

the 1963–1974 period are based on film badge dosimetry records and other data. The generic 

pit model was constructed because of the paucity of film badge records during these early 

years of operation, and because national security considerations prevent NIOSH from 

revealing the details of the actual weapons assemblies that were handled at IAAP. The 

generic pit was therefore designed to be a bounding, claimant-favorable model that is not 

based on classified data. However, it is also not based on a valid scientific analysis of the 

actual conditions of radiation exposure during that time period. The result is a sharp 

discontinuity between the external doses estimated for that period and for the 1963–1974 

period, because the external dose assessments for these two periods use very different 

methodologies. The inconsistent methods of dose reconstruction for these two periods could 

result in an inequitable resolution of claims from workers exposed during these two periods. 

In the TBD, NIOSH has adopted an approach for reconstructing pre-1963 doses based on the 

generic pit model, and doses for the 1963–1974 period using film badge data. This results in a 

discontinuity in dose estimates in 1963. This is illustrated in Figure 6.8 of the TBD and in 

Appendix G, where photon dose estimates made by NIOSH for the period of operation are 

shown. 

By far, the largest fraction of the external photon dose from a bare, unshielded pit composed of 

15-year-old plutonium, at a distance of 100 cm from the body, is contributed by Am-241. 

According to NIOSH, maximum ingrowth of Am-241 occurred by 1960 (ORAU 2005, Appendix 

G). This conclusion is based on historical evidence that plutonium was first produced in 1945. 

NIOSH thus made the conservative, claimant-favorable assumption that all pits handled during 

the period 1949–1960 were made of plutonium produced in 1945. In the years following 1960, 

5

 As of April 2005, NIOSH was considering a dose assessment model for IAAP extremity exposures. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

24 of 92 

NIOSH assumed that the plutonium was 15 years old. Although the TBD contains some general 

observations regarding the role of IAAP and other nuclear weapons facilities, no specific reason 

is given for the 15-year cutoff of Am-241 ingrowth. Lower dose rates prior to 1960 reflect less 

Am-241 ingrowth, as described in Tables 6.6 and 6.7 of the TBD and in Appendix G. 

The results of dose reconstruction, applying the approaches specified in the TBD for photon 

doses for the periods 1949–1962 and 1963–1974, are shown in Table 1, below. The photon 

doses in the three energy ranges are taken from Appendix G of the TBD. The doses for the 

1949–1962 period are based on the MCNP-calculated hourly dose rates at 1 m from the generic 

pit, an assumed 2,000-hour work-year, and the work factor discussed earlier. The doses for the 

1963–1964 period are based on the film badge data for each year, adjusted for the energyresponse of the film badge and corrected for Hp(10). 

Table 1 shows the following results: 

• The GM values of total photon doses between 1949 and 1962 range from 6,861 to 

10,239 mrem/y. The values for 1949–1962, listed in Table 1, have an arithmetic mean of 

8,916 mrem/y 

• The GM values of total photon doses between 1963 and 1974 range from 418 to 

1,391 mrem/y, for an arithmetic mean of 912 mrem/y. 

It is evident from Table 1 that there is a sharp decline in the estimated doses in 1963 that is due 

to the different methods of dose reconstruction for the pre-1963 and post-1962 periods. This 

difference is about 1 order of magnitude. Compensation decisions for pre-1963 workers would 

thus be based on bounding estimates driven by the need to protect national security data, rather 

than on a scientific analysis of the radiological conditions actually prevailing at IAAP during that 

time. Compensation decisions for post-1962 workers, on the other hand, would be based on an 

assessment of dosimetry records for that period. 

There is, of course, general agreement that national security data on pit design cannot be and 

should not be disclosed. The resulting discrepancy in the estimated doses, however, would make 

for compensation decisions that are not equitable for claimants who were exposed during these 

two periods, or scientifically valid for the earlier period. This finding is made, notwithstanding 

SC&A’s other comments on the issues relating to the gaps in the post-1962 film badge records, 

such as cohort badging and its effect on the post-1962 dose estimates (see Finding 4). 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

25 of 92 

Table 1. Annual Median External Photon Doses─HP(10) (mrem/y) 

Year <30 keV 30-250 keV >250 keV Total 

1949 243 5699 919 6861 

1950 257 6039 974 7270 

1951 272 6379 1029 7680 

1952 283 6634 1070 7987 

1953 293 6889 1112 8294 

1954 304 7145 1153 8602 

1955 315 7400 1194 8909 

1956 326 7655 1235 9216 

1957 337 7910 1276 9523 

1958 344 8080 1304 9728 

1959 355 8335 1345 10,035 

1960 362 8505 1372 10,239 

1961 362 8505 1372 10,239 

1962 362 8505 1372 10,239 

1963 39 923 149 1111 

1964 15 347 56 418 

1965 19 446 72 537 

1966 21 487 79 587 

1967 22 515 83 620 

1968 30 698 113 841 

1969 25 584 94 703 

1970 43 1014 164 1221 

1971 49 1156 186 1391 

1972 34 789 127 950 

1973 46 1090 176 1312 

1974 44 1039 168 1251 

Finding 4: The statistical significance or representativeness of annual dose distributions for 

1963–1967 (Table 6.4 of TBD) is not clearly established, since only a limited number of 

radiation workers were monitored prior to 1968. Furthermore, missed doses due to the erratic 

use of film badges cannot be estimated. This problem is compounded by the paucity of data 

for reliably assigning monitored workers to radiological job categories. 

In Table 8 of Revision 00 of the TBD (ORAU 2004), NISOH indicates that, for the period 1963– 

1967, only 3% to 7% of IAAP workers were monitored for external penetrating radiation; 

slightly more than in earlier years, albeit the number of dosimeter readings increased, as shown 

in Table 6.4 of Revision 01 of the TBD. Interviews with former workers also revealed that many 

workers did not wear their badges in these early years. Those that did wear badges attached 

them to their lapels or collars, whereas the maximum radiation exposure was likely at waist 

level. According to these workers, there was limited enforcement of good health physics 

practices. For instance, airborne tritium release alarms were often turned off, or the alarm set 

point was raised to avoid alarms. While some of these issues are addressed by NIOSH (e.g., 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

26 of 92 

excluding zero badge readings and planning to include a correction factor for badge geometry), 

others remain unresolved. 

With a reported 300–400 workers on Line I at that time, it is not clear what jobs were performed 

by this handful of badged workers (some workers moved between jobs regularly), and whether 

these jobs are truly representative of jobs that entailed exposure to external radiation. University 

of Iowa researchers established that a number of workers who entered radiation areas of the plant 

were not badged, even after 1963. Security guards were not monitored, although they were 

responsible for overseeing the receiving and shipping of weapon assemblies and for guarding 

storage areas housing multiple pits. However, radiographers and Line I supervisors were 

routinely badged; thus, production workers and guards are under-represented in the NIOSH dose 

assessment model. 

The worker outreach meetings conducted by NIOSH on July 29, 2004, revealed that IAAP 

workers sometimes did not wear their film badges, even when they were working with 

radioactive materials, such as assembly and disassembly of nuclear warheads. According to the 

TBD (p. 41): 

During worker outreach meetings in July 2004, a new issue with missed dose 

was identified. The issue concerned the radiological monitoring practices at 

the site. Through discussions with former IAAP workers who conducted both 

assembly and disassembly, NIOSH discovered that film badge dosimeters may 

not have been worn all of the time. One worker indicated that he always wore 

his film badge, while another indicated that he would only wear it when one 

was given to him. Through this discussion, it became apparent that in general 

workers were supposed to wear their film badges, but strict adherence was 

not necessarily enforced. As a result, a third scenario occurred in which a 

worker was issued a dosimeter badge but did not wear it during exposure to 

radiation. When this badge would be processed, this could also result in a 

zero reading. The effect of these three scenarios is that there is likely some 

missed or unrecorded dose (Figure 6.4). As shown in Figure 6.4, in 1966 

approximately half of the dosimeter readings were below the detectable or 

reporting level. 

One of the results of this situation is that the missed dose resulting from exposure below the limit 

of detection is not distinguishable from missed dose when the worker did not wear his/her badge. 

NIOSH has attempted to resolve this issue in a claimant-favorable way by dropping all zero 

badge readings from the statistical analysis that is used in the TBD for external dose estimation. 

This approach is claimant favorable for non-radiological workers or for those workers who had 

only minimal exposure to nuclear materials or other sources of radiation. This is not the case for 

workers with exposures at the high end of the range. Appendix F of the TBD shows graphs 

depicting the lognormal distributions of the non-zero data. Dosimeter readings at the high end of 

the range are consistently higher than the corresponding values on the curves fitted to these data. 

This calls into question the use of lognormal distributions to represent these data. The approach 

used to fitting the non-zero data points does not, on the face of it, appear to be claimant favorable 

for the most exposed workers if the fitted values are used in the dose reconstruction. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

27 of 92 

This approach to missed dose also leaves a significant issue of how the non-zero badge readings 

are to be interpreted in relation to total dose. Because of the intermittent wearing of the badges 

by some workers, the badges may not have recorded all of the occupational exposure of the 

worker during the given time period. In view of the potential for missed dose in badges with 

non-zero readings, NIOSH’s conclusion that dropping badges with zero readings “overestimates 

the true dose” is not statistically supportable, especially as NIOSH has so far identified only one 

worker who remembers wearing his badge whenever he was in radiation areas. This is clearly 

insufficient as a basis for establishing a statistically valid approach, even for workers in the same 

job category as this individual. 

A claimant-favorable approach to dose reconstruction not only involves dropping zero dose 

readings from the analysis (which is a necessary first step), but also requires the development of 

a statistically valid procedure for estimating the missed doses in the non-zero badge readings. 

Adjusting the dosimeter records for the missed dose due to erratic wearing of film badges 

requires the following steps: 

• The fraction of time during the work year that workers who had non-zero film badge 

readings wore badge needs to be estimated, along with a measure of the variability of that 

time estimate. 

• The typical radiological conditions (i.e., dose rates) prevailing at the times when badges 

were worn relative to the times when they were not need to be established. 

• The above information needs to be classified by job category, so that the proper 

adjustment factors can be applied to the records of the claimant for whom the dose 

reconstruction is being done. 

These factors are likely to be very difficult or impossible to estimate for IAAP. 

A final aspect of the available film badge records is that it is unclear whether IAAP had adopted 

the practice of cohort badging. The job number and partial classification data gathered by 

University of Iowa researchers indicates that this may have been the case. The assumption in the 

TBD that “workers who directly handled radioactive materials at IAAP are expected to have 

been routinely monitored and dosimetry data should be available” was made without analysis of 

the possibility of cohort badging at IAAP. 

Finding 5: It may not be possible to accurately determine external doses from Am-241, due to 

the low sensitivity of the film badges to the low-energy photons emitted by this radionuclide. 

Some film badges of that era employed a filter of 1 g/cm2

 of lead. The calculated attenuation of 

60 keV photons by such a filter is over 98%. Hence, we have some doubt that the recorded 

external HP(10) dose from Am-241 can be determined with any reasonable certainty. This issue 

applies to both post-1962 and pre-1963 dose reconstructions because the 1962–1974 film badge 

data are used to derive the work factor, which is an integral part of the model developed in the 

TBD to address 1949–1963 dose reconstructions. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

28 of 92 

Finding 6: Film badges worn on the lapel or collar may not accurately represent organ doses. 

Adjustment factors are therefore needed for organ doses. 

In the July 29, 2004, worker outreach meetings conducted by NIOSH, the issue of the location of 

the organ relative to the dose and the location of the badge was brought up by the workers: 

Workers reported experiencing heat and tingling in the pelvic area and legs 

when working in close proximity to the pits and weapons. Badges were issued 

to workers in these areas, but the badges were worn on the collar, not the 

pelvis. 

Furthermore: 

Dosimeter badges were approximately 2 inches in length and 1 inch wide. 

Dosimeter badges were generally worn on collars (lapels), however, most of 

the work and materials were at waist level or below. 

SC&A raised this issue with NIOSH during the conference call of April 13, 2005. NIOSH 

agreed that organ-specific correction factors needed to be developed to account for the organversus-film badge geometry issue. NIOSH has estimated that a factor of 2.5 would apply to 

organs in the pelvic area. 

The adjustment factor would vary by organ and would apply to Line I workers on the assumption 

that they were exposed only to the pit they were working on. However, Line I workers may have 

been exposed to more than one pit at a time. Finally, SC&A has not investigated whether 

adjustment factors may be necessary for other workers, such as security guards, in part because 

the data for such an analysis do not exist. 

Finding 7: The IAAP TBD did not consider all relevant and significant sources of data and 

information important to dose reconstruction. In general, there is an over-reliance on 

theoretical modeling for purposes of deriving upper-bound estimates at the expense of 

identifying and applying available radiological and operational information to achieve “a 

substantial basis of fact,” as stipulated by 42 CFR 82. 

Site expert interviews indicate that the following relevant records were generated during the 

operation of IAAP and were transferred to Pantex in 1974: 

• Landauer film badge dosimeter design and calibration information (available from 

Landauer, according to company personnel). Significance: It may be possible to confirm 

actual dosimeter specifications and response from company records. 

• Battelle neutron dose rate and spectral measurements (identified by SC&A and requested 

from Battelle on April 7, 2005). Significance: The neutron-to-photon ratios derived 

from Pantex data are surrogates for neutron dose rate and spectral measurements at 

IAAP, which the Battelle measurements can provide. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

29 of 92 

• Contamination and area radiation survey records. Significance: Interviewed workers 

attest to the routine workplace surveys that took place; these measurements would enable 

an assessment of potential sources of radiation exposure over time, would serve to 

complement the relatively small number of intermittent film badge readings in the early 

years, and would enable an assessment of radiation fields in production areas where 

multiple pits were being handled. 

• Routine facility swipe test data. Significance: Would confirm or refute the TBD 

assertion that there is no evidence of surface contamination of assemblies and pits, and 

no breaches of pit cladding. 

• Routine bioassay records. Significance: Would validate the dose assessments based on 

workplace concentrations of tritium and the strip chart air monitoring results. 

• Production and safety standard procedures. Significance: Would ascertain prescribed 

worker procedures regarding assembly and disassembly of devices, and pit storage 

requirements, and would clarify radiation protection and monitoring practices. 

• Classified incident reports. Significance: The paucity of reported production-related 

radiological incidents at IAAP (those reported as radiation-related typically involve 

radiography incidents), as compared with the comparable Pantex operational history, 

may be suggestive of an incomplete record of such occurrences, some of which may have 

been classified on national security grounds. 

A number of these records were not identified, requested, nor reviewed by NIOSH for their 

significance to the TBD and to dose reconstruction. According to NIOSH, some of these may 

have been “mis-boxed” at Pantex, and therefore not yet located. 

Additional records sources that should be pursued include the TN&Associates repository in Oak 

Ridge, Tennessee; the Rock Island Arsenal Archives in Illinois; and records collections at Rocky 

Flats, the Y-12 Plant, the Savannah River Site, and the DOE Albuquerque Operations Office. A 

comprehensive classified review of IAAP records held at Pantex would be important to ascertain 

the status and availability of key records. 

Finding 8: SC&A’s classified review substantiated the basis for the use of the 1993–2003 

Pantex neutron-to-photon ratios as a claimant-favorable surrogate for IAAP neutron dose 

estimates. However, workers whom we interviewed said that neutron dose rate and spectral 

measurements had been taken at IAAP by a DOE laboratory. The lack of a review of actual 

IAAP data raises concerns both about the accuracy and reasonableness of the neutron-tophoton ratio proposed in the TBD and about the completeness of NIOSH’s document 

research. 

According to Section 6.2.2 of the TBD, the neutron film badge dosimetry employed at IAAP was 

inadequate and the neutron contribution to doses from HEU and weapons-grade plutonium was 

significant. Figure 6.2 of the TBD shows 129 neutron-to-photon ratios that range from about 

0.03 to about 0.6, with a GM of 0.135 and a GSD of 2.02. Furthermore, according to the TSD, 

the measured neutron-to-photon ratio is likely to be an underestimate because the NTA film did 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

30 of 92 

not accurately measure the dose delivered by neutrons with energies less than 800 keV. (In fact, 

the NTA film has a lower neutron energy threshold of about 700 keV and has limited sensitivity 

to neutrons below about 1 MeV.) Based on MCNP calculations of the generic pit, and a further 

claimant-favorable adjustment, NIOSH doubled the GM of the neutron-photon ratio to 0.27, and 

assigned a rounded value of 2.0 to the GSD. 

As indicated in Section 6.5.4 of the TBD, NIOSH also reviewed the neutron-to-photon ratios 

observed at Pantex during the period of 1993 through 2003. Figure 6.9 of the TBD indicates that 

the neutron-to-photon ratios tend to follow a lognormal distribution, with a GM of 0.79 and a 

GSD of 1.57. According to NIOSH, these neutron-to-photon ratios are conservative for the 

purpose of dose reconstruction at IAAP because the photon doses at Pantex were measured with 

TLDs worn below lead aprons. As a result, the photon dose is reduced, resulting in a neutron-tophoton ratio that is biased high. On this basis, NIOSH elected to use the Pantex-based neutronto-photon ratios with a GM of 0.79 and a GSD of 1.57 for reconstructing neutron doses at IAAP. 

The neutron dose derived in this manner is then adjusted by the ICRP 60 neutron weighting 

factor, which is a function of the neutron energy spectrum. As noted in the TBD: “. . . the 

neutron energy distribution for the generic pit was relatively evenly split between the fission and 

fast neutrons.” In the case of a real pit, the cladding would slow the fast neutrons, causing a 

downward shift in the neutron energy spectrum. NIOSH therefore made the claimant-favorable 

assumption that fission neutrons (with energies of 0.1–2 MeV) would account for 100% of the 

neutron dose. The ICRP 60 correction factor of 1.91 for fission spectra neutrons was therefore 

applied to the estimated neutron doses. 

However, NTA dosimetry records are not the only data available for reconstructing neutron 

doses at IAAP. From interviews with former workers, SC&A learned that Battelle Northwest 

Laboratory (now Pacific Northwest National Laboratory) had performed actual measurements of 

neutron spectra and doses at IAAP during production operations. NIOSH subsequently 

contacted a PNNL health physicist who interviewed one of two Battelle researchers on what was 

confirmed to be a multi-year survey of neutron spectra measurements conducted at a number of 

DOE nuclear weapons facilities. In a memorandum to file dated April 6, 2005 (see Attachment 

7), it is noted that: 

• One of the first trips to IAAP to measure neutron dose rates from pits and weapons 

assemblies took place in 1972 

• Some of the information regarding the neutron dose rates measured in this and 

subsequent trips to IAAP may be classified 

• Measurements were made with “rem-meters, TEPCs [tissue equivalent photon counters], 

and multi-spheres” 

• Neutron measurements were recalled as being “comparable” to those taken at Pantex. 

NIOSH has confirmed that a neutron dosimetry analysis by Battelle did take place at IAAP. It 

informed SC&A that it was attempting to retrieve available data. The discovery by SC&A of a 

crucial record of IAAP data raises questions regarding the comprehensiveness of the NIOSH 

data review and whether the data set being used is sufficiently complete. NIOSH has indicated 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

31 of 92 

that the use of the Pantex neutron-to-photon ratio is more claimant favorable than the use of the 

Battelle data. However, the existence of actual dosimetric data raises the question of whether it 

is scientifically supportable to use Pantex data in preference to IAAP data to estimate neutron 

doses at IAAP, given that 42 CFR 82 requires that preference be given to actual measurements 

over surrogate data in the hierarchy of dose reconstruction. 

Finding 9: External dose estimates for unmonitored workers are claimant favorable for nonradiological workers. They are not scientifically valid or claimant favorable for unmonitored 

workers who were frequently in the proximity of radiological materials. 

The TBD states that external exposures were experienced primarily by personnel who worked in 

facilities at Line I, the Yard C storage area, the Explosive Disposal Area, and the Firing Site, and 

that these workers represented only a small fraction of the workers at the facility. Film badges 

were used for area monitoring at a number of locations, including various assembly buildings, 

Gravel Gerties, and Storage Igloos. Dosimeters used for area monitoring were collected biweekly from 1962 to the end of operations. About 70% of the badges in the non-storage areas 

had readings less than the minimum detection limit (MDL) of 10 mR. Figure 4.1 of the TBD 

plots the cumulative probability distribution of the biweekly exposures and reveals a GM of 

6 mR per 2 weeks with a GSD of 4.6. Assuming 2,080 work hours per year, worker external 

exposures for those years had a GM of 37 mR/y and a GSD of 4.6. In order to give the benefit of 

the doubt to the claimant, the TBD suggests that the dose reconstructor may also assume an 

upper-bound dose of 260 mrem/y for unexposed (non-Line I) workers. 

As applied to individuals who are believed to have had job responsibilities with little potential 

for occupational facility external exposure, this approach appears to be scientifically correct and 

modestly claimant favorable for the years during which these environmental measurements were 

made. The extent to which these doses apply to years prior to 1962, however, is uncertain. 

SC&A also questions the scientific basis for using dosimeter MDL values as a means for 

deriving the “upper-bound” environmental dose of 260 mrem/yr for “non-line 1” workers. The 

use of this value is not claimant favorable for storage area workers, who were not monitored. 

Figure 4.2 of the TBD presents area dosimetry data collected from 1962 to 1974 for the Fissile 

Material Storage Area. Discussions with NIOSH regarding the storage areas revealed that these 

readings, which ranged from about 100 mR to 2,000 mR over any given 2-week period, were 

taken from within the storage areas (i.e., Storage Igloos), and that these storage areas were only 

occasionally entered by workers to retrieve and replace pits, and for inventory purposes. 

However, another group of IAAP workers was exposed to significant, and possibly higher, levels 

of radiation during many of their working hours. These were security guards who would likely 

have spent much of their time inside the Storage Igloos, as attested by the interviews summarized 

in Attachment 4. The maximum exposure of a security guard whose post was in the location that 

had the highest recorded readings could have exceeded 10 R/y. Moreover, it is our 

understanding that such individuals were not classified as radiation workers and therefore were 

not monitored. The TBD makes no reference to this group of individuals and their significant 

potential exposures. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

32 of 92 

Finding 10: The radon concentrations presented in the TBD are not scientifically valid or 

claimant favorable, due partly to a scientifically incorrect choice of data from Pantex in Texas 

for use in Iowa, which has much higher radon levels than Texas. 

The only available radon measurements at IAAP were conducted between 1989 and 1991, over 

15 years after the period of operations. Since the measurements cannot be linked to specific 

buildings, these data cannot be used for dose reconstruction for workers who occupied the 

Gravel Gerties. However, according to the TBD, the mean, the standard deviation, and the GM 

of these measurements are less than a comparable set of measurements from Pantex. NIOSH 

therefore adopted radon levels measured in underground buildings at Pantex as surrogate data for 

calculating radon exposures of IAAP workers in the Gravel Gerties. These radon concentrations 

have a GM of 1.51 pCi/L and a GSD of 1.75. 

However, radon levels in structures are highly dependent on the specific geographic locations. 

In light of the regional and even local variations in radon levels, the assumption that measured 

radon levels at Pantex are representative of the radon levels at IAAP, which is stated in the TBD, 

is not warranted. This is especially so in light of the fact that Iowa has high background radon 

levels; by contrast, Texas has relatively low radon levels, according to William Field of the 

University of Iowa (Field 2005). 

Data gathered by the Iowa Department of Public Health and by Dr. Field (Field 2005) indicate 

that radon levels of several hundred picocuries per liter are quite plausible for the Gravel Gerties: 

The Iowa Department of Public Health has numerous documented indoor radon 

gas concentrations in Iowa exceeding 400 pCi/L. . . I have personally measured 

many underground service tunnels and crawl spaces in Iowa that exceed 200 

pCi/L. 

However, no firm or statistically supportable value can reasonably be established without 

building a structure that would closely resemble the Gravel Gerties and actually carrying out 

radon measurements over a suitable period of time. Dr. Field (Field 2005) believes that 10 pCi/L 

is the “lowest possible value” of radon level that can be used to make minimum dose estimates 

for IAAP: 

Based on what we know about radon occurrence in Iowa in underground 

structures, over 50% exceed a year-long average radon concentration of 4 pCi/l. 

Given the construction of these facilities I would use 10 pCi/L as the lowest 

possible value. We do not know about ventilation patterns so that is a real 

unknown.6 

Further information is found in the National Residential Radon Survey (EPA 1993). According 

to this EPA report, Iowa has the highest average levels of indoor radon in U.S. households. The 

report presents the results of a survey that included measurements made in 5,694 homes, drawn 

from a survey of 11,423 homes. This population was drawn from an eligible universe of nearly 

72 million households out of the 93 million households in the United States. EPA collected data 

6

 Dr. William Field, personal e-mail communication with Arjun Makhijani, May 27, 2005. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

33 of 92 

in three categories: (1) lowest lived-in level; (2) average concentration over all lived-in levels; 

and (3) average concentration in the lowest level of non-living space. The average for Iowa is 

3.64 pCi/L, while the average for Texas is 0.83 pCi/L, which is among the lowest in the country. 

In view of the above considerations, SC&A concurs with Professor Field’s recommendation that 

10 pCi/L be used as the radon concentration for minimum dose calculations. No reasonable dose 

estimate or upper-bound estimate can be made for the Gravel Gerties, given the lack of sitespecific data and the special nature of the structures. 

Finding 11: Assumptions about worker exposures to medical x-rays are not uniformly 

claimant favorable. 

According to the TBD, the dose reconstructor should assume that (1) all workers received an 

annual posterioanterior (PA) chest x-ray from 1947 through 1975, (2) assembly workers received 

semi-annual PA chest x-rays, and (3) radiography workers received quarterly PA chest x-rays. If 

the job description is not known, the dose reconstructor should assume semi-annual PA chest 

x-rays. The dose reconstructor should employ the standard organ doses provided in ORAUTOTIB-0006 (ORAU 2003) for different time periods of employment. Table 3.2 of the TBD lists 

the parameters of lognormal distributions of doses to various organs of workers who are 

assumed, on the basis of their job category, to have received lumbar spine x-rays at IAAP. The 

guidance for reconstructing occupationally related medical x-ray exposures was based on 

information gathered during the worker outreach meeting, limited IAAP records, and an 

assumption that medical x-ray practices at IAAP were similar to those at Pantex and Rocky Flats. 

For the most part, this guidance seems reasonable, claimant favorable, and consistent with other 

site profiles. However, given the time frame of facility operation, there is good reason to believe 

that fluoroscopic examinations may have also been employed in the early period. If such 

examinations were employed, the exposures could have been substantially higher than those 

described in the TBD. In addition, we are concerned about the examination frequency that is 

most appropriate when a worker cannot be assigned to a specific worker category. It would be 

more appropriate to give the claimant the benefit of the doubt by assigning a dose corresponding 

to a quarterly chest x-ray rather than a semi-annual one. 

Finding 12: Tritium exposure estimates are exceedingly claimant favorable, but some of the 

assumptions that yield the higher dose estimates are not scientifically valid. 

According to Section 5.1 of the TBD, tritium reservoirs were shipped to IAAP beginning in 

1954. NIOSH assumes that Line I workers experienced tritium intakes every year from 1954 

until 1975. Since no bioassay data are available, NIOSH employs (1) air-sampling data gathered 

at IAAP from 1959 through 1964, (2) models simulating the handling of the tritium containers, 

and (3) experience and data gathered at the Pantex facility in the 1970s and 1980s, as the basis 

for estimating tritium intakes at IAAP. NIOSH explains that information gathered from 

interviews with a radiation safety engineer at Pantex (who also worked for a time at IAAP), and 

process similarities between the two facilities provide reasonable assurance that Pantex data can 

be used as a surrogate for tritium exposures at IAAP. 
 

Effective Date: Revision No. Document No. Page No. 

June 29, 2005 0 (Draft) SCA-TR-TASK1-0009c 34 of 92 

For tritium, NIOSH developed a model that assumed two sealed tritium containers (referred to as 

“JP containers”) were vented per day, and that the head space, which had a calculated volume of 

0.0136 m3

, had a tritium concentration equal to the release limit of 90 uCi/m3 . Based on these 

data, the daily release rate was calculated to be 2.445 uCi, and was assumed to be uniformly 

mixed in the interior volume of the Gravel Gertie, which was 437 m3 . A bounding air 

concentration of 2.043 μCi/m3

 was derived by assuming no building ventilation and a continuous 

buildup of tritium over 1 year. Workers were assumed to have a breathing rate of 1.2 m3

/hr and 

to be exposed to this concentration for 2,000 hours per year. This resulted in a tritium intake of 

4,902 μCi/yr and an effective dose of 0.331 rem/yr, assuming that the tritium was in the form of 

water vapor. NIOSH believes that this model of tritium exposures is conservative, because two 

urine samples analyzed biweekly from selected individuals who worked in areas with high 

potentials for tritium intake did not detect tritium intakes. If the exposures postulated by the 

models had occurred, the TBD states that positive results would have been observed in the 

bioassay program. For these reasons, NIOSH believes that the hypothetical models for tritium 

intake by Line I workers place an upper bound on the potential exposures. Furthermore, the 

TBD states that if tritium intakes occurred, they were likely primarily elemental tritium, as 

opposed to tritiated water. This assumption is characterized in the TBD as a further conservative 

assumption embedded in the analysis. 

On the assumption that the quantities of tritium released during operations were, in fact, 

accurately characterized in the TBD, SC&A concludes that the methodologies employed in the 

TBD to reconstruct historical tritium exposures to Line I workers represent a bounding analysis 

that is highly claimant favorable. The below-MDL results for the two urine samples also provide 

a marginal basis for supporting the conclusion that NIOSH’s model for tritium dose is claimant 

favorable. However, the assumptions of complete oxidation, no removal of tritium by 

ventilation, and that all the tritium remained within the structure are not scientifically reasonable. 

Claimant-favorable dose estimates could be made without such extreme assumptions. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

35 of 92 

6.0 OBSERVATIONS 

1. No mention is made in the TBD (ORAU 2005) of the extensive use of “flash x-ray” 

technology, which was used during hydroshots to perform high-speed diagnostic analyses 

of high explosives at the moment of detonation. NIOSH needs to ascertain whether the 

energies involved were detectable by the film badge dosimeters that were worn by the 

radiographic operators during the period when this equipment was used at IAAP. 

2. The accuracy of air-sampling techniques employed during the hydroshots and in the 

FS-12 tunnel requires further evaluation. The methodology used to collect and analyze 

the air samples has an impact on the results. For example, use of wet chemistry for 

analysis of filters versus counting with a scintillation detector would result in different 

values if appropriate correction factors were not applied. 

3. Trace amounts of plutonium were detected in IAAP drummed waste, raising questions 

regarding incidents or circumstances where the encapsulation of pits may have been 

breached. A routine environmental survey conducted by T N & Associates, Inc., 

(TN&A 2001) noted that waste being shipped to Pantex contained trace amounts of 

plutonium (estimated at a concentration level of 16 mg/kg). While the source of this 

contamination may have been discarded swipes or analytic samples, the presence of 

fissile material, regardless of amount, brings into question the assertions that no instances 

can be identified where encapsulated pits had been breached, and that no weapons 

assemblies or components were received with surface contamination. A review of 

available records, both classified and unclassified, has yet to identify the likely source of 

this contamination. NIOSH should perform a further document review to resolve this 

issue. 

4. Section 5.4 of the TBD mentions encapsulated sources of enriched uranium, thorium, and 

“perhaps” Po-210, yet there is no subsequent treatment of those radionuclides in the 

discussion of external doses. For example, as stated on page 34 of the TBD, some 

weapons may have contained 210PoBe initiators with the capsule or the pit. There is no 

mention of how this may affect external exposure or the neutron energy spectra. Also, 

there is no mention of what was done with those radiation sources after disassembly. 

NIOSH notes that these sources were encapsulated or sealed. Therefore, it was assumed 

that they were not sources of air contamination or resuspension that could lead to internal 

radionuclide deposition. However, the possibility of nicking the pits during handling or 

the possible presence of tramp uranium and plutonium on the surface of the pits indicates 

that workers may have been internally exposed to other radionuclides besides tritium and 

DU. Furthermore, the fact that these sources were encapsulated does not preclude the 

presence of tramp material, which may have significantly contaminated exterior surfaces. 

The NIOSH assumption of “careful control of contamination before release of 

components to production. . .” [emphasis added] does not preclude internal exposures. 

This conclusion requires verification of the procedures used before the pits were handled 

and weapons were assembled, especially since bioassay data have not been recovered. In 

addition, swipe samples apparently were collected from the pits, but the results were not 

reported; nor were the limits of detection reported for the swipe samples for the 

radionuclides of interest (i.e., isotopes of uranium, plutonium, and thorium). Uncertainty 
 

Effective Date: Revision No. Document No. Page No. 

June 29, 2005 0 (Draft) SCA-TR-TASK1-0009c 36 of 92 

about internal doses from incidents therefore remains an issue. Resolving this issue 

would require documentation about screening of surfaces for the presence of tramp 

material, knowledge of engineering controls in work environments, and whether 

respirators were used to eliminate this uncertainty in the absence of routine bioassay data 

(except for tritium). 

5. In the interest of efficiency, NIOSH uses assumptions that are sometimes excessively 

conservative and scientifically implausible. One example, cited in Finding 12, are the 

models used to reconstruct the doses to environmental releases of tritium and the tritium 

doses to Line I workers inside the Gravel Gerties. As another example, on page 31 of the 

TBD, the mass of oxidized DU is estimated by multiplying the volume of the dust by 

11 g/cm3, the density of solid UO2. The bulk density of the loosely packed powder, 

however, is less than 2 g/cm3 . Although this assumption is claimant favorable, it is not 

scientifically valid. 

6. In Section 2.2.2, the TBD contains the following statement from a report identified as 

Mitchell 2003: 

. . . it was the military’s responsibility to mate the AEC-delivered warhead to 

the military’s delivery system, usually a missile. Working two 12-hour shifts, 

(seven days a week) at the Burlington Plant, this new design entered the 

stockpile in December 1956 in an “Emergency Capabilities” status as the 

W-25 warhead. [Emphases added.] 

NIOSH assumed a work year of 2,000 hours in deriving the work factor used to estimate 

pre-1963 external doses. The actual work year would not matter if the work hours were 

the same in the pre-1963 and post-1962 eras. The statement quoted above calls this 

assumption into question. 

7. The assessment of exposures to DU in the TBD includes a number questionable 

assumptions and parameter values. In Section 5.2 of the TBD, NIOSH explains that 

workers may have been internally exposed to airborne particles of DU as a result of 

(1) disassembly of old DU bomb parts, (2) hydrotesting (which involved the implosion of 

simulated weapons made of DU), and (3) machining of baratols, which are the explosive 

charges that encased the DU pits. As explained in the TBD, very little air sampling was 

done to monitor exposures of workers to airborne DU, because DU was believed to be 

relatively non-radiotoxic. SC&A has the following observations about NIOSH’s DU 

dose estimation assumptions and procedures: 

• On page 27 of the TBD, it is stated that DU particle sizes have a lognormal 

distribution of 0.1 to 1 μm, yet the assumed size is 1 μm. The GM of such a 

distribution is about 0.3 μm. ICRP has published dose coefficients for this 

particle size—the effective dose from inhalation of Type M U-238 is about 50% 

greater than for 1 μm AMAD. Using 0.3 μm would result in dose estimates that 

are larger by a factor of 2. Hence, the choice of 1 μm is not scientifically valid or 

claimant favorable. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

37 of 92 

• The use of the 1974 resuspension data, as described on page 28 of the TBD, is not 

necessarily claimant favorable, because DU deposited in prior years had time to 

“weather in”—be eroded, washed away, or move downward into the soil. 

Therefore, the dust loading due to resuspension in 1974 is likely to underestimate 

the resuspension factor and associated dust loading for earlier years. 

• Section 5.2.2 of the TBD addresses potential internal exposure to inhaled DU due 

to the machining of baratols. Barotols were the plastic explosives that encased the 

DU spheres that simulated real weapons. During machining of baratols, some of 

the DU frequently became nicked and aerosolized. The machining of barotols 

was replaced by pressing of explosives in about 1962. The TBD explains that 

inhalation exposures via this pathway were likely small and intermittent, when 

compared to other DU exposure scenarios. In order to place an upper bound on 

the possible exposures associated with nicking, the TBD assumed that the DU 

dust loading was 2% of the maximum permissible concentration for 20 hours per 

week. These assumptions appear to be somewhat arbitrary. They should be 

documented. In the absence of documentation or analysis, there is no assurance 

that they represent a reasonable upper bound for this scenario. 

• On page 30 of the TBD, the assumed ingestion rate is inconsistent with the EPA 

Exposure Factors Handbook (EPA 1997) and is much lower than typical values 

recommended for use in site assessment. 

• Section 5.2.3 of the TBD states, “The median airborne release fraction was 3 x 

10-4 and the median respirable fraction was 0.5; the upper bound values for the 

same parameters were 2 x 10-3 and 0.3.” This statement, which is copied from the 

DOE Handbook, contains a self-contradiction. If the median fraction was 0.5, 

how can 0.3 be an upper bound? Table A.41d of the Handbook reproduces the 

published experimental data. These data show a maximum airborne fraction of 

particles of respirable size = 5.9 × 10-4 from 1 kg of “DUO” dropped from a 

height of 3 m. The details of the ash collection are unknown; the handling may 

have stirred up dust as the ashes were swept into bags, etc. Consequently, the 

highest observed airborne fraction of respirable particles should be used as a 

fixed, conservative, claimant-favorable value. This is about the same value as the 

upper bound cited in the TBD, but is four times the median value. 

• Section 5.2.4 of the TBD states that the median value for the airborne release 

fraction for the free fall spill of UO2 from a height of 1 m is 0.00008. Given the 

assumed particle size (respirable fraction of 0.5), this value for the release fraction 

seems unreasonably low. Is the DOE value selected for UO2 airborne release 

derived from experiments? Why is it much lower than the values given in the 

TBD for ash from DU burning (page 30 of the TBD), although the citation is the 

same? Also, the upper-bound value for the respirable fraction for DU ash is less 

than the median value. This is an error. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

38 of 92 

• On page 31 of the TBD, the median value of the 1-m spill data is not claimantfavorable inasmuch as the 3-m data have a maximum respirable release fraction 

that is 15 times higher. The assumptions about the volume of air and the exposure 

duration are unsupported. The dispersion is the result of handling and processing 

the material—a person performing this work would experience a higher air 

concentration than if the dust were uniformly dispersed in a medium-sized room, 

as is assumed in the TBD. There is also no justification for limiting the exposure 

to 1 hour per day. The DU intake could be much higher than is estimated by the 

TBD, especially since the value is treated as a constant upper bound. 

• External exposures of workers to DU are discussed in Section 6.2.3 of the TBD. 

NIOSH used MCNP to model the bremsstrahlung spectra from U-238 spheres, 

which are depicted in Figure 6.3. NIOSH appears to have made the same error as 

in other site profiles, in that it assumed that only the bremsstrahlung from beta 

rays emitted by Pa-234m, a member of the short-lived progeny of U-238, 

contributes to the external dose. In fact, as was documented in the SC&A report: 

“Audit of Case No. 1 from the Blockson Chemical Company” (SC&A 2004a), 

omitting the γ-rays emitted during the decay of the short-lived progeny of U-238 

could lead to an 80% underestimate of the organ dose. This observation pertains 

to the scientific accuracy of the NIOSH analysis—NIOSH did not utilize these 

results in its assessment of external exposure to DU at IAAP. NIOSH did cite the 

results of an analysis of the external dose from a semi-infinite slab of natural 

uranium metal—certainly a limiting case for the present analysis. The Hp(10) 

dose rate was 2 mrad/h, while the Hp(0.07) dose rate was 230 mrad/h. The Hp(10) 

doses would most likely be recorded by the film dosimeters, while the Hp(0.07) 

doses, primarily due to β-rays and low-energy, may not have been recorded. 

• Skin and extremity doses are not explicitly addressed in this revision of the TBD, 

but are held in reserve for future consideration (see Section 6.5.5 of the TBD). In 

light of the analysis cited in Section 6.2.3 of the TBD, it appears that external 

exposure to DU is not an important contributor to the deep dose as compared to 

the other sources of photon exposures. However, skin and extremity doses appear 

to be potentially significant and are to be the subject of a future revision to the 

TBD. 

• One of the scenarios that could have resulted in the intake of airborne particles of 

DU was hydroshots performed at the South Firing Site 6 (FS-6). During these 

tests, most personnel were about 1 mile away from the test, but some personnel 

were located in bunkers close to ground zero. After the tests, the personnel in the 

bunkers drove to the test site to retrieve instruments. These workers did not wear 

respirators. The TBD states that several hundred hydroshots were performed, 

with only a limited amount of air sampling. The highest airborne DU 

concentration, 21.82 μg/m3

, was observed in the FS-12 tunnel that connected 

ground zero to the bunker; the highest airborne concentration at 100 m from 

ground zero was 9.12 μg/m3

 (see Table 5.2 of the TBD). These measured 

airborne concentrations were used to derive the intakes of DU by personnel at the 

FS-12 tunnel, at 100 yards, and at 1 mile from the shots. The exposures from 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

39 of 92 

each of the several hundred hydroshots were estimated by assuming that each 

exposure lasted 30 minutes and that the breathing rate was 1.2 m3/h. The TBD 

provides no rationale for the duration of the exposure, nor is it apparent that the 

limited number of measurements is representative of the DU airborne 

concentrations experienced by the workers. 

• Section 5.2.1 of the TBD describes methods used to derive the airborne DU levels 

at other locations at the site. However, the methods described in the TBD do not 

appear to follow conventional atmospheric dispersion modeling. As a result, it is 

difficult to judge whether the approach is scientifically valid and claimant 

favorable. 

• The potential for inhalation of resuspended particles of DU during recovery of 

instruments and the potential for inadvertent ingestion of DU are discussed in the 

TBD. Inadvertent ingestion due to contamination of hands (page 28 of the TBD) 

was assessed using an ingestion model that SC&A believes is technically flawed. 

NIOSH should consider the information provided in EPA’s Exposure Factors 

Handbook (EPA 1997). The exposures associated with resuspension were 

estimated using air-sampling data; exposure durations and Lung Clearance Types 

appear to be scientifically valid and claimant favorable. 

• Work areas where workers picked up and handled pieces of DU are described in 

the TBD. The description indicates that there may have been a significant 

potential for shrapnel to penetrate the skin and become lodged in the body. Such 

incorporation of small pieces of metal may be a source of long-term exposure. 

For instance, a 10-mg spherical DU metal particle has a radius of only 0.5 mm. 

This would mean a one-time incorporation of a small fraction of the DU that got 

onto the hands every time there was a clean-up task would result in a nonnegligible body burden. NIOSH estimates hand contamination of 76 mg per 

clean-up task (page 28). The possibility that frequent cleanup of DU metal may 

have resulted in significant body burdens needs to be evaluated for IAAP. This 

evaluation is especially necessary in light of the abnormally high rate of urinary 

cancer that has been reported by the workers in the NIOSH July 29, 2004, worker 

outreach meetings. 

• Section 5.2.3 of the TBD presents the methods used by NIOSH to estimate the 

inhalation exposures to workers who bagged the ash produced as a result of 

burning about 2,000 g/y of DU contained in scrap explosives. It was assumed that 

about 10 g of DU were bagged per workday. The TBD presents a series of 

assumptions for predicting the fraction of the bagged DU that may have become 

airborne during bagging. Many of the assumptions appear to be rather arbitrary 

since data and scientific analysis are not provided to support them. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

40 of 92 

7.0 COMPLETENESS, ACCURACY, AND DATA ADEQUACY 

7.1 COMPLETENESS OF DATA 

NIOSH has investigated a number of classified and unclassified sources of data and archives in 

preparing the TBD (ORAU 2005). However, as discussed in Section 5 of the present report, 

there are a number of sources of data that NIOSH failed to utilize in preparing the TBD. For 

instance, NIOSH did not use available information on radon in tightly sealed indoor structures in 

Iowa. 

Based on worker interviews conducted by SC&A and an inventory of available records 

maintained at Pantex, we have concluded that the classified documents provided to SC&A in 

support of this review do not constitute a complete set of references needed to adequately 

evaluate the TBD for technical adequacy and completeness of data. A number of interviewees 

identified key documents that were compiled during the 1949–1974 history of the plant that 

either have not been located or have not been made available for review. This information 

includes bioassay data, early film badge dosimetry data, complete radiation and contamination 

survey data, production and radiation safety procedures, and criticality safety specifications. It is 

also not clear if additional radiological incident reports, including classified ones, exist for the 

periods in question and, in particular, before 1959, for which period no radiological incident 

reports have been located. NIOSH has indicated that earlier feedback from DOE suggested that 

some records may have even been misplaced as a result of “re-boxing” of IAAP records at 

Pantex. 

Recognizing this significant shortfall, SC&A made a formal request to NIOSH for expedited 

access to such information, whether classified or unclassified, in a letter dated April 11, 2005 

(provided as Attachment 2). A response to this request has not yet been received. It has been 

rendered moot for most claimants by the decision of the Advisory Board to recommend an SEC 

for IAAP AEC workers from 1949 to 1974. However, these data will be useful in reconstructing 

doses for non-SEC cancers. 

7.2 TECHNICAL ACCURACY 

In several areas, NIOSH has adopted reasonable, claimant-favorable approaches to dose 

estimation. Examples may be found in NIOSH’s approach to some aspects of DU and tritium 

exposure. However, in other areas, NIOSH’s approach is not scientifically valid even when it is 

claimant favorable, as in the estimation of tritium doses in the Gravel Gerties. 

The most important issue of technical accuracy relates to the generic pit model. As discussed in 

Section 5 of the present report, SC&A’s classified review corroborated the TBD analysis that the 

generic pit dose rate represents an upper-bound estimation for workplace external radiation 

fields at a distance of 1 m from a single pit for the pre-1963 period. However, the use of the 

work factor is questionable on scientific grounds. Furthermore, the use of the generic pit model 

results in a large discrepancy in the calculated external doses for the pre-1963 period, compared 

to the external doses, based on dosimetry data, during later periods. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

41 of 92 

As discussed in Finding 3 (Section 5), the use of the generic pit model for estimating external 

doses in 1949–1962, and the use of film badge data for later years, produces a sharp 

discontinuity in the external dose estimates for 1963 and later years. The result is that inequities 

are introduced into the dose reconstruction for post-1962 workers that are a result of the use of 

very different methodologies for the two time periods. The pre-1963 methodology was adopted 

because of the paucity of film badge data for those years, and because the detailed data on the 

nuclear weapons handled at IAAP during that time are classified. Thus, the dose reconstruction 

model for the earlier years is neither realistic nor scientifically valid. 

The accuracy of external dose reconstructions is further compromised by the method of 

analyzing the film badge data, as discussed in Section 5 of the present report. The method of 

dropping zero badge readings, as described in the TBD, does not assure that missed doses due to 

erratic use of film badges by radiological workers would be captured in a scientifically valid 

manner. We also question the use of the lognormal distributions derived from these data, which 

are not claimant favorable for workers whose jobs subjected them to radiation exposures near the 

high end of the distributions. 

Finally, the use of Pantex photon-to-neutron dose ratio, while claimant favorable, does not meet 

the test of technical accuracy, since NIOSH failed to use available Battelle measurements on 

neutron dose that were made at IAAP. 

7.3 DATA ADEQUACY 

The film badge data are inadequate for accurate dose reconstruction that would give claimants 

the benefit of the doubt in the face of substantial uncertainties. This is because: 

• Only a limited number of radiation workers were monitored prior to 1968. 

• Many exposed workers, including security guards, were never monitored. 

• Cohort badging may have been practiced, which precludes an assumption that the 

workers most at risk were monitored. 

• Missed doses due to erratic use of film badges cannot be estimated due to lack of data. 

7.4 COMPLIANCE WITH REGULATIONS AND PROCEDURES 

As described in Sections 5 and 7.2, the generic pit model used for dose reconstructions for pre1963 workers was adopted because of the paucity of film badge data for those years and because 

the detailed data on the nuclear weapons handled at IAAP during that time are classified. This 

raises the question whether these assessments constitute “reasonable estimates” of radiation dose, 

as defined by 42 CFR 82. The regulation specifies that, “estimates [are to be] calculated using a 

substantial basis of fact and the application of science-based, logical assumptions to supplement 

or interpret the factual basis.” SC&A believes that use of the generic pit model broaches a policy 

question of how “reasonable estimates” can be achieved, in accordance with EEOICPA and 

42 CFR 82, when national security considerations take precedence. This issue is particularly 

important because of the inequities in the dose estimation of pre-1963 workers compared to those 

in the 1963–1974 period, stemming from the use of the generic pit model for the earlier period. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

42 of 92 

8.0 REFERENCES 

Environmental Protection Agency, U.S. (EPA), 1993. National Radon Database, Volume 6: 

National Residential Radon Survey, 402-R-93-013, Washington, DC. 

Environmental Protection Agency, U.S. (EPA), 1997. “Exposure Factors Handbook,” 

EPA/600/P-95/002F, Washington, DC. 

Field, R.W., 2005, Letter dated April 22, 2005, to Paul Zeimer and other members of the 

Advisory Board on Radiation and Worker Health. 

National Institute of Occupational Safety and Health (NIOSH), 2000. “External Dose 

Reconstruction Implementation Guideline,” OCAS-IG-001, Rev. 1, Cincinnati, Ohio. 

Oak Ridge Associated Universities (ORAU), 2003. “Dose Reconstruction from Occupationally 

Related Diagnostic X-ray Procedures,” ORAUT-OTIB-0006, Rev. 0, Oak Ridge, Tennessee. 

ORAU, 2004. “Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP),” ORAUT-TKBS-0018, Rev. 00, Oak Ridge, Tennessee. 

ORAU, 2005. “Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP),” ORAUT-TKBS-0018, Rev. 01, Oak Ridge, Tennessee. 

S. Cohen & Associates (SC&A), 2004a. “Audit of Case No. 1 from the Blockson Chemical 

Company,” McLean, Virginia. 

SC&A, 2004b. “SC&A Standard Operating Procedure for Performing Site Profile Reviews,” 

McLean, Virginia. 

SC&A, 2005a. “Integrated Review of NIOSH Site Profile for The Atomic Energy Operations at 

the Iowa Army Ammunition Plant (IAAP),” SCA-TR-TASK1-0009, McLean, Virginia. 

SC&A, 2005b. “Integrated Review of NIOSH Site Profile for the Atomic Energy Operations at 

the Iowa Army Ammunition Plant (IAAP),” SCA-TR-TASK1-0009b, McLean, Virginia. 

TN & Associates, Inc. (TN&A), 2001. “Work Plan for Supplemental Remedial Investigation for 

Line 1 (Including Historical Site Assessment) for the US Army Corps of Engineers,” TN&A 

Report 01-0000910, final draft. 

Traub, R.J., R.I. Scherpelz, and T.D. Taulbee, 2005. “Health Physics Analysis of Dose Received 

at the Iowa Ordnance Plant,” PNNL-ETD-0385 (classified report). 

U.S. Code of Federal Regulations, “Methods for Conducting Dose Reconstruction under the 

Energy Employees Occupational Illness Compensation Program Act of 2000,” Part 82, Title 42, 

“Public Health.” 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

43 of 92 

ATTACHMENT 1: KEY QUESTIONS FOR NIOSH/ORAU REGARDING 

SITE PROFILE DOCUMENTS 

March 22, 2005 

To: Paul Ziemer and Lewis Wade 

From: John Mauro 

Subject: TBD for the Atomic Energy Operations at the Iowa Army Ammunitions Plant 

(IAAP) 

In order to expedite the review process for the IAAP TBD, SC&A has prepared an initial set of 

questions and requests for information. We would like to discuss these matters with 

representatives of NIOSH and the Board as soon as possible and hope to maintain an active 

dialogue with them throughout the expedited review process. 

General Questions: 

1. What is the basis for NIOSH’s assertion that pre- or post-1962 film badge data are 

sufficiently representative to be used as a basis for "co-worker" dose assignment for highenergy photons or neutrons? Can any of the data collected be corroborated or verified? 

2. NIOSH accepts DOE documentation that all enriched uranium, plutonium, thorium, and 

“perhaps Po-210,” were encapsulated or sealed, and therefore unavailable for 

contamination or resuspension that could lead to internal depositions. Without routine 

bioassay data (except for tritium), regular contamination surveys, or workplace air 

monitoring results, from the early years, how can NIOSH substantiate this assumption? 

Did former worker interviews substantiate that there were no instances of radioactive 

resuspension or release? 

3. It is indicated in the site profile regarding the unexplained Cs-137 contamination that 

“Mr. Shannan said he was unaware of any Cs-137 used at IAAP other than small sealed 

sources at uCi levels as instrument check sources.” However, it seems plausible that 

either or both Cs-137 and Co-60 (another unexplained source of contamination) may 

have been used to detect voids in the high explosives (HE) that were produced and 

formed at IAAP, a common practice at other DOE sites. (A key concern at the time was 

the presence of “voids” within the explosive that would decrease its effectiveness.) Has 

NIOSH investigated how such voids were routinely detected using radioactive sources in 

that era at Pantex and Los Alamos? Assuming that such high activity sources were, in 

fact, in common use at the site, what potential contribution to worker dose can be 

assumed? 

4. No work locations or job categories are provided in the IAAP profile. How can work 

factors (relative time spent in proximity to a pit) or even potential exposures (e.g., for 

specific work activities, such as burning DU) be estimated? Has NIOSH investigated and 

established any specific work locations or job categories for former IAAP workers that 

can be used in co-worker dose estimates? 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

44 of 92 

5. If significant quantities of light elements were present in the plutonium pits (e.g., 

beryllium or oxygen), there could conceivably have been more neutrons released from 

alpha-n reactions than from spontaneous fission in the even-number plutonium isotopes. 

How did NIOSH take this possibility into account in its calculations? 

6. Did NIOSH consider in its dose calculations the possibility of pits containing U-233 at 

the IAAP, and, if so, what range of U-232 contamination was assumed in its calculations? 

(There is evidence in the open literature that U-233 weapons were tested at 

approximately the same time period as the early years of IAAP operation.) 

7. NIOSH assumed that plutonium pits would be considerably more radioactive than pits 

containing uranium as the fissile material. Therefore, the dose calculations presented in 

the TBD were based on plutonium pits. However, this assumption may not necessarily 

be bounding if uranium pits had been fabricated from uranium containing significant 

contamination from U-232. 

8. Could NIOSH clarify the dates for weapons disassembly, assembly, and retrofitting at 

IAAP? 

9. Why did NIOSH decide to use source-term data rather than radiological field data, such 

as radiation and contamination surveys, or a combination of both? 

10. NIOSH mentions the existence of swipe data in the TBD. Where are the results of these 

data? Also, what was the methodology used to take swipe samples and analyze the 

swipes for trace levels of weapons grade plutonium? What was the lower limit of 

detection for WGP in the swipe samples? Did NIOSH evaluate what the potential 

inhalation and/or ingestion dose to weapons handlers may have been if the levels of 

surface contamination on the weapons were just below the limits of detection for swipe 

samples analyzed at that time? 

11. What types of Radiation Generating Devices were used at IAAP? 

12. On page 14 of the SEC Petition Evaluation Report, Petition SEC-0006-1, radium is 

mentioned as a radionuclide present at IAAP. Why was radium excluded from 

consideration in the TBD? 

13. There have been suggestions in the press that a criticality accident may have occurred at 

IAAP. Has NIOSH investigated these claims? If so, what was the outcome? 

14. We suspect that a great deal of experimental work in weapons development was 

performed in the late 1940s and throughout the 1950s. An example is the use of 

radioactive lanthanum as a means to evaluate the performance of the implosion device 

design. Since radioactive lanthanum is an extremely strong gamma emitter and was 

produced in large quantities at INEEL during the late 1950s, has NIOSH researched the 

possibility that some workers may have received external exposures that may have been 

uniquely associated with the early years of weapons experimentation and development? 
 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

45 of 92 

15. What is the basis for the assumption that workers were 100 m away during burning DU? 

Furthermore, if workers were closer, the Gaussian diffusion approach used in Section 

4.2.2 may not be valid. Did NIOSH evaluate other methods of estimating DU exposure? 

16. Is NIOSH using a distribution of neutron to photon ratio of 0.27 with a GSD of 2.0 for its 

dose calculations as indicated on p. 38? If so, this does not appear to be claimant 

favorable, as claimed. The graph on p. 37 shows a 95 percent value from the empirical 

lognormal distribution of just over 0.4. When adjusted for the undercounting of 800 KeV 

neutrons of up to 40%, a reasonable upper bound based on this data would appear to be 

about 0.4/0.6 ≈ 0.67. Please explain in greater detail the choice of the parameters on p. 

38 as claimant favorable. How are uncertainties arising from the use of area badges for 

individual dose calculations taken into account? How were considerations relating to the 

geometry of the area badge locations relative to the source taken into account in 

estimating the photon-to-neutron ratio? 

17. NIOSH notes that the neutron dose ratio “greatly depends on weapon design” (p. 38). 

How has NIOSH assessed that the generic pit described in Appendix D gives a claimantfavorable value for neutron dose? Have classified computations been done to compare 

doses estimated for this generic pit to doses expected from actual designs used in the 

early period? 

18. The lognormal fits of weekly dosimeter data from 1962 onward seem to systematically 

underestimate dose at the high end of the readings. Has NIOSH analyzed this issue? 

Furthermore, the removal of zero readings (Section 6.3.1) may not give a claimantfavorable value for the total dose, since the zero readings corresponded to workers not 

wearing badges during periods of potential exposure. Has NIOSH considered the 

development of an explicit upper bound missed dose for periods when zero doses were 

recorded and an associated procedure for integrating these doses into the total dose 

estimate? 

19. The external dose from Th-232 decay products seems not to have been considered. If so, 

the bases for not including exposures from Th-232 should be provided. 

20. Has NIOSH evaluated the potential dose from incorporation of DU metal slivers or 

shrapnel when workers handled pieces of metal to bag them? 

Specific Questions: 

21. p. 11. In Section 2.2.2 of the TBD, the following statement is quoted from a report 

identified as Mitchell 2003: 

. . . it was the military’s responsibility to mate the AEC-delivered warhead to 

the military’s delivery system, usually a missile. Working two 12-hour shifts, 

(seven days a week) at the Burlington Plant, this new design entered the 

stockpile in December 1956, in an “Emergency Capabilities” status as the W25 warhead. [Emphases added.] 
 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

46 of 92 

The IAAP TBD has modeled exposure to workers that assumes 2,000 hours per year as 

representative of an average annual working period. In light of the statement made by 

Mitchell (2003), 2,000 hours per year does not appear appropriate. Are there data 

available that would suggest a significantly higher number of working hours per year? 

(In the absence of data, a reasonable assumption might include a 12-hour per day work 

shift and a 60-hour workweek; an upper-bound value may include an 84-hour workweek. 

p. 11. In addition to the above-cited statement regarding “. . . the new design,” Mitchell 

(2003) further stated in Section 2.2.2 of the TBD, that: 

The sealed pit design weapons precipitated several fundamental changes in 

the nuclear weapons complex. New facility designs were required and 

constructed at Burlington and Pantex to accommodate production work 

involving encapsulated SNM for the first time at either site. [Emphases 

added.] 

What was the scope of these “fundamental changes . . . [and] new facility designs” at 

both Burlington and Pantex? And, to what extent did these changes affect worker 

exposures that would raise questions about the use of post-1963 data for modeling pre1963 exposures? 

23. p. 16. For environmental dose assessment, Section 4.2.1 identifies annual onsite H-3 

releases as being either 6,000 μCi/yr or 26,000 μCi/yr and for claimant favorability 

assumes the latter. For internal uptake by facility workers, Section 5.1 identified the 

bounding release value of 1.22 μCi from the headspace of a single JP container, which 

contained the tritium reservoir. Tritium air concentration was defined for a single Gravel 

Gertie into which 2 x 1.22 μCi were introduced each day; this would suggest the 

processing of >21,300 JP containers and at 730 JP container per year per Gravel Gertie 

involve the steady operation of 36 Gravel Gerties in order to account for the release of 

26,000 μCi/yr. Was the release of H-3 from the headspace of JP containers the sole or 

primary source of H-3 release to the environment and source term for worker exposure? 

22. p. 17. Section 4.2.2. NCRP calculation of airborne activity is based on average annual 

atmospheric dispersion values (χ/Q values), not upper bound. A more conservative, 95th 

percentile value should be considered, such as that provided in Nuclear Regulatory 

Commission guidance, which lists default atmospheric conditions as Class F, u = 1 m/s. 

The values for these conditions, calculated according to the algorithm in the NRC code 

XOQDOQ, and assuming that the wind blows into the worst sector 25% of the time, are 

as follows: 

Q = 2.788e-4 g/s TBD (u = 2 m/s) NRC (u = 1 m/s) 

Distance (m) P C (f = .25) P C (f = .25) 

100 3.5E-3 1.22E-07 3.07E-02 2.14E-06 

500 2.00E-04 6.97E-09 1.96E-03 1.37E-07 

1000 5.00E-05 1.74E-09 6.18E-04 4.31E-08 

The assumption in the TBD that the calculated values represent worst-case assumptions is 

not correct. The NRC methodology (or some comparable method) should be used to 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

47 of 92 

calculate the 95th percentile values. As shown above, the increase in concentration is 

more than one order of magnitude. The 25% wind direction assumption is reasonably 

conservative. 

25. p. 17. In Section 4.2.2, devoted to the environmental intake of depleted uranium from 

burning sites, the entire estimate of material handled in the burn yard, 2000 g/year, is 

assumed to be released to the environment. However, it is pointed out in Section 5.2.3 

that airborne release fractions from burning depleted uranium are generally 10-3 or 10-4 

(DOE 1994). Please explain the apparent contradiction. 

26. p. 22. Section 4.3 defines ambient external radiation levels for “area radiation 

monitoring” at locations defined as (1) non-storage areas and (2) storage areas. Figure 

4.2 defines area-monitoring data for the years 1963–1974. For Fissile Material Storage 

Areas, bi-weekly doses ranged as high as 2,000 mR or 6 mR/hr from photons alone. 

(Potential neutron doses could potentially double this dose rate.) Since it is reasonable to 

assume that the Fissile Material Storage Areas required continuous surveillance and 

monitoring by security personnel, as well as routine entry by other workers, the following 

questions are suggested: (1) How do the area dose rates depicted in Figure 4.2 relate to 

potential doses received by security personnel possibly assigned full-time to the four 

storage igloos?, and (2) Based on the shielding afforded by storage igloos, what were the 

potential dose rates inside the storage igloos to which select personnel would have been 

exposed upon entry? 

27. p. 22. At the bottom of page 22 of the TBD, Mr. Shannan, former Radiation Safety 

Manager at the IAAP, is quoted as saying that during his employment at the facility, 

contamination outside or inside the incoming containers was “rare.” This section goes 

on to state that the radionuclides most likely to have resulted in an intake at IAAP were 

depleted uranium and tritium. Since there are no bioassay records, how is it possible to 

rule out an internal exposure to plutonium in the course of one of these “rare” 

contamination incidents? Has NIOSH concluded that the IAAP incident records are 

complete in regard to all radiological incidents? 

28. p. 23. In the bottom paragraph on page 23 of the TBD, it is stated that 122 mrem is 

indicative of a chronic annual uptake of 430 microcuries of tritium. Then at the bottom 

of the 2nd paragraph on page 24, a chronic tritium intake estimated to be 4902 microcuries 

per year is associated with a tritium dose of 0.331 rem/year. Please explain the apparent 

discrepancy. 

29. p. 26. Data from the “FS-12 tunnel” were used for the DU air concentration because the 

data “were more robust.” No information is given regarding the location of the FS-12 

tunnel, so that a reviewer cannot determine if that location serves as a suitable surrogate 

for the air concentrations experienced by the workers. 

30. p. 27. Particle sizes have a lognormal distribution of 0.1 – 1 μm, yet the assumed size is 

1 μm. The geometric mean of the distribution is about 0.3 μm. ICRP has dose 

coefficients for this particle size—the effective dose from inhalation of Type M 238U is 

about 50% greater than for 1 μm AMAD. 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

48 of 92 

31. p. 27. The factor of 4 decrease at 2 miles from the 1-mile concentration is not claimant 

favorable. The χ/Q at 1 mile for Class F, u = 1 m/s is 2.87E-4 while at 2 miles under the 

same conditions χ/Q = 1.05E-4, which clearly is not a factor of 4 decrease. 

32. p. 27. The argument about the high density of DU is countervailed by the very small 

particle size, which would minimize deposition. 

33. p. 27. The assignment of a 2-hour exposure time, with the parenthetical statement 

“assumes turbulence type A at 4000 m and 1 m/s drift speed...” is not clear. The logical 

process needs to be spelled out; otherwise, it cannot be reviewed. A reasonable estimate 

of the integrated exposure can be made by integrating over the X-axis of the Gaussian 

puff. The total mass of suspended material is 4,000 kg × 10% ÷ 701 shots = 0.57 kg. 

Assuming 95th percentile conditions, the integrated intakes for the periods in question are 

as follows: 

Period of exposure 

Total Intake 

TBD Calc 

December 2, 1965 through March 3, 1969 7.63E-02 1.06E+01 

March 4, 1969 through July 14, 1969 4.32E-04 5.98E-02 

July 15, 1969 through December 31, 1973 2.42E-02 3.35E+00 

The calculated intakes, which represent default 95th percentile conditions, are more than 

100 times larger than the TBD estimated values. A more realistic, site-specific estimate 

can be obtained from the STAR (STability ARray) data for Burlington, IA, which are 

available from the National Climatic Data Center. These data sets can be used as input 

to various computer codes, which calculate atmospheric dispersion factors. 

34. p. 28. The analysis of the ingestion of DU by the cleanup crew does not appear to be 

scientifically valid. The experiment described in Section C-2.0 is not a valid foundation 

for the ingestion rate. Ingestion of contaminants by the hand-to-mouth route is 

notoriously difficult to estimate. It has been the subject of numerous studies, some of 

which are discussed in the EPA Exposure Factors Handbook. This body of knowledge 

should be considered and incorporated into the analysis. 

35. p. 28. Adopting the second highest air concentration as the constant concentration needs 

further discussion. The complete data set on which this conclusion is based should be 

presented. 

36. p. 28 . Use of the 1974 resuspension data is not necessarily claimant favorable. Despite 

there being no additional deposition of DU, the DU previously deposited has had time to 

“weather in;” therefore, the resuspension factor is likely to have decreased over time. 

37. p. 29. Section 5.2.2. The assumption that 2% of the MPC is an upper bound should be 

documented. 
 

 

 

 

Effective Date: Revision No. Document No. Page No. 

June 29, 2005 0 (Draft) SCA-TR-TASK1-0009c 49 of 92 

38. p. 30. Top of page. The assumed ingestion rate is inconsistent with the EPA Exposure 

Factors Handbook and is much lower than typical values recommended for use in site 

assessment. 

39. p. 30. Section 5.2.3. Six lines up from the end of the first paragraph is the statement: 

“The median airborne release fraction was 3 x 10-4 and the median respirable fraction was 

0.5; the upper bound values for the same parameters were 2 x 10-3 and 0.3.” This 

statement, which is copied from the DOE Handbook, contains a self-contradiction: If the 

median fraction was 0.5, how can 0.3 be an upper bound? Table A.41d of the handbook 

reproduces the published experimental data. These data show a maximum airborne 

fraction of particles of respirable size = 5.9 × 10-4 from 1 kg of “DUO” dropped from a 

height of 3 m. The details of the ash collection are unknown; the handling may have 

stirred up dust as the ashes were swept into bags, etc. Consequently, the highest observed 

airborne fraction of respirable particles should be used as a fixed, conservative, claimantfavorable value. This is about the same value as the upper bound cited in the TBD, but is 

4 times the median value. 

40. p. 31. In the third paragraph in Section 5.2.4 of the TBD, it is stated that the median 

value for the airborne release fraction for the free fall spill of UO2 from a height of 1 

meter is 0.00008. Given the assumed particle size (respirable fraction of 0.5), this value 

for the release fraction seems unreasonably low. Is the DOE value selected for UO2 

airborne release derived from experiments? Why is it different from and much lower 

than the values given in the TBD for ash from DU burning (p. 30), though the citation is 

the same? Also the upper bound value for the respirable fraction for DU ash is less than 

the median fraction. This appears to be in error. 

41. p. 31. The short paragraph in the middle of the page estimates the mass of oxidized DU 

by multiplying the volume of the dust by 11 g/cm3

, the density of the UO2 crystal. The 

bulk density of the loosely packed powder, however, is less than 2 g/cm3 . Although this 

assumption is claimant favorable, it is not scientifically correct. 

42. p. 31. The use of the median value of the 1-m spill data is not claimant-favorable (see 

comment in paragraph 40, above), inasmuch as the 3-m data has a maximum respirable 

release fraction that is 15 times higher. The assumptions about the volume of air and the 

exposure duration are unsupported. The dispersion is the result of handling and 

processing the material—a person performing this work would experience a higher air 

concentration than if the dust were uniformly dispersed in a medium-sized room, as is 

assumed in the TBD. There is also no justification for limiting the exposure to 1 hour per 

day. The DU intake could be much higher than estimated by the TBD, especially since 

the value is treated as a constant upper bound. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

50 of 92 

43. p. 32. Radon levels measured at Pantex are assumed in the TBD to be “the best 

indicators of radon exposure at IAAP.” These measured levels given in Table 5.6 appear 

comparable to the average radon levels in homes of about 1.25 pCi/L 

(http://www1.umn.edu/eoh/hazards/hazardssite/radon/radonmonitor.html). Since radon 

levels in structures are very sensitive to the specific geographic locations of these 

structures, the assumption made in the TBD that measured radon levels at Pantex are 

representative of the radon levels at IAAP does not appear to be warranted. 

44. p. 33. Section 5.4 (Other Sources), page 33 of 79, states: 

Enriched uranium (EU), plutonium, thorium, and perhaps Po210 were present 

at various times during assembly or disassembly of nuclear weapons. All of 

these sources were encapsulated (sealed), and with the careful control of 

contamination before release of components to production was allowed, it is 

unlikely these radioelements would have been available for intake. 

[Emphases added.] 

The fact that these sources were encapsulated does not preclude the presence of tramp 

material, which may have significantly contaminated exterior surfaces. Unless such 

surfaces were first screened for the presence of tramp material and/or work environments 

were subject to strict engineering controls, use of anti-Cs, respirators, etc., the above 

stated assumption of “careful control of contamination before release of components to 

production. . . “ [emphasis added] does not preclude internal exposures. In the absence of 

bioassays, air monitoring, and/or relevant swipe survey data of nuclear materials, what 

supportive documents served as the basis for the conclusions stated in Section 5.4? 

45. p. 34. In the first paragraph in Section 6.2.1 of the TBD, the existence of radiation 

generating devices and large Co60 sources at the IAAP is acknowledged. These sources 

may have resulted in significant doses to workers, particularly during the period prior to 

1963, when radiation was frequently treated irresponsibly by both management and 

workers in the United States. Moreover, the last sentence of the third paragraph in 

Section 6.3 states that most of the pocket dosimeter results (allegedly used between 1965 

and 1974) appear to be “related to using high level radioactive source (sic) for 

radiography.” However, the basis for the estimate of the doses prior to 1963, as 

described in Section 6.5.1.1 of the TBD, is a generic theoretical pit, and does not consider 

any doses from these sources. Please explain the basis for this assumption. 

46. p. 35. At the end the first paragraph in Section 6.2.1 of the TBD, photons resulting from 

n, gamma interactions in the “nuclear components and building materials” are mentioned 

as a potential contributor to dose. Yet, no consideration is given to this source in the dose 

estimate prior to 1963. In particular, we are concerned about the activation of structural 

materials by thermal neutrons in the presence of moderating materials. Have any 

calculations been made that corroborate the validity of neglecting these potential 

contributions to exposure? 

47. p. 36. We concur that the external dose from EU is lower than from an equal mass of 

plutonium, and that the assumption that all the pits were plutonium is claimant favorable. 
 

 

 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

51 of 92 

However, the statement in middle of page: “Since the low energy photon dose from 

enriched uranium is negligible, only the plutonium pits had the potential for significant 

low energy photon dose” is incorrect. The dose rate from EU is not negligible; this 

statement might lead to the neglect of potential radiation sources in other contexts and 

should be corrected. It is also not clear why the TBD focuses on “low-energy” photons. 

The MCNP analysis presented later in the TBD addressed all the photon radiation from 

the generic plutonium pit. 

48. p. 38. Section 6.2.3. As it did in the TBD for the Blockson Chemical Company, NIOSH 

focused exclusively on the bremsstrahlung radiation from β rays while overlooking the 

contribution of X and γ rays from the short-lived daughter products of 238U to the external 

dose rate. SC&A's calculations of the dose from external exposure to a drum of 

yellowcake showed that bremsstrahlung contributed less than 20% to the effective dose. 

Thus, 80% of the dose was overlooked in that case. The external dose from DU is not 

addressed further in this TBD. 

49. p. 44. The TBD states that the 241Am photopeak contributes 70% of the total dose. In 

fact, the data presented in Appendix D show that 78% of the dose is due to photons with 

energies less than 70 keV. 

50. p. 44. Since little is known about the dosimeters employed at IAAP, the most 

conservative assumptions must be used in the dose assessments. Some film badges of 

that era employed a filter of 1 g/cm2

 of lead. The calculated attenuation of 60 keV 

photons by such a filter is over 98%. Hence, there is serious doubt whether the external 

dose from 241Am can be determined from the dosimetry with any reasonable certainty. 

51. p. 45. Section 6.4.2. NIOSH should provide more detailed results of the MCNP 

calculations of the neutron spectra so that the conclusions stated in the TBD can be 

independently verified. While we agree that the neutron dose from a bare pit of weaponsgrade plutonium is a minor component of the external dose, the same is not true if there 

are significant amounts of plutonium oxide present. The (α, n) reaction with oxygen 

produces a strong neutron source. (See Question 5.) Since the neutron spectra at IAAP 

are unknown, and since the MCNP calculations apparently rely on classified data, it is not 

possible to independently assess this potentially significant component of the worker 

dose. 

52. p. 47. Section 6.5.1.1. Equation 6.1 is an expression for Wf, the work factor, in terms of 

DAnnual, the calculated annual dose, and DERA, the dose rate for a given era, which is 

derived based on classified information (and therefore cannot be reviewed at this time). 

The expression DAnnual appears again in Equation 6.2 where it is defined in terms of Wf. 

NIOSH should adopt a different symbol if, as it appears, DAnnual has a different meaning 

in the two equations. Otherwise, the definitions are circular. 

53. p. 49. Table 6.6 is not understandable. DGeneric, calculated in Appendix D, is the dose 

rate from the generic pit as registered by the dosimeter. It is not clear what RAm-241 

represents— it is not proportional to the ingrowth of 241Am, which proceeds at a much 

faster rate. Thus, we do not understand the meaning of the Modeled Annual Dose. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

52 of 92 

54. p. 50. Table 6.7 is apparently based on the MCNP calculations. The column headed 

“Am Component” does in fact increase in proportion to the ingrowth of 241Am. The last 

column reproduces the values from Table 6.6, again without explanation. Please explain. 

55. p. 51. Section 6.5.3. The prescription for adjusting the dose is not clear. 

56. Appendix B. Appendix B contains years of assembly and disassembly for various 

delivery systems. Some of the disassembly dates are after 1975. Where were these 

delivery systems disassembled? 

57. Appendix D. It is not clear that the assumed mass of 6 kg of plutonium in the bare pit is 

claimant favorable. It is not logical to assume that all the plutonium-based weapons 

handled at IAAP were no bigger than the first two plutonium bombs that were made in 

1945, given the emphasis on higher yields in the 1950s. Likewise, the EIS for Pantex is 

not necessarily the definitive statement on the subject. Finally, there are different isotope 

mixes in different references, all of which are classed as “weapons-grade plutonium.” 

NIOSH needs to specify the isotopic composition of the plutonium that was used for the 

generic pit analysis. Are the isotopic distributions of plutonium available in the classified 

literature for each of the pits handled at the IAAP? If not, did NIOSH evaluate doses for 

the plutonium isotopic distributions characteristic of the full range of potential weapons 

usable material? For example, did NIOSH evaluate the doses from reactor grade 

plutonium? (There is evidence in the open literature that the AEC tested weapons 

composed of reactor grade plutonium.) 

58. Appendix D. The IAAP period of facility operation (i.e., 1949–1975) brackets the period 

of nuclear weapon testing in the Pacific (and, therefore, nuclear weapon production) that 

involved devices with yields up to 15 megatons. Appendix D describes the 6 kg Pu 

Generic Pit specifications as “. . . the approximate mass of plutonium used in the Trinity 

and Nagasaki nuclear devices” and further states that “. . . a mass of 6 kg is considered 

claimant favorable.” Is the use of the Generic Pit as the model source-term for the years 

1949 through 1962 a claimant-favorable model? 

59. Appendix D. Table D.1 of the TBD identifies photon dose rates by energy groups. Are 

dose rates cited as mrem/hr defined for the deep dose (i.e., HP(10))? Is the “Total 

Photon” dose rate of 33.3 mrem/hr a hypothetical value that would be expected as the 

“recorded” value for a dosimeter with 100% precision? Is the 14.8 mrem/hr assigned to 

the “Film Badge Energy” the expected HP(10) dose rate recorded by a two-element film 

dosimeter located at a distance of 100 cm from a generic pit? 

Information Requested: 

1. We request access to the “Top Hat” database to review recorded interviews conducted by 

NIOSH of IAAP workers. 

2. We request access to the number of workers monitored to match the numbers of 

dosimeters referenced in Table 6.4, Rev. 1. (The number of workers was used in Rev. 0, 

but was switched to number of dosimeters in Rev. 1.) 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

53 of 92 

3. We request copies of documentation reporting the 15 incidents that involved radioactive 

materials cited in Appendix E. 

4. Table 2.1, in Section 2.2.4 of the TBD, identifies “Significant Radiation Safety Program 

Events” by year of implementation, along with several references to Ahlstrand in 1956– 

1958. A review of Ahlstrand 1956(b) and 1958(a) (IAAP Project History Reports) does 

not provide sufficient data describing radiological policies, worker training, and other 

issues relevant to radiological safety. However a reference is made to a “Manual of 

Standard Practices,” which apparently was revised routinely over time. Can copies of the 

“Manual of Standard Practices” (with successive revisions) be made available to SC&A 

for review? 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

54 of 92 

March 31, 2005 

To: Paul Ziemer and Lewis Wade 

From: John Mauro 

Subject: TBD for the Atomic Energy Operations at the Iowa Army Ammunitions Plant 

(IAAP). Addendum to IAAP questions (based in part on 3/21/05 interview w/ Univ. 

of Iowa investigators) 

The following are additional questions which supplement the questions contained in our March 

22nd letter, and which we would like to discuss with NIOSH and the Board at our upcoming 

meeting. Some of the questions are new based on our ongoing investigations, including expert 

interviews, and some represent a further development of several of the questions we raised in our 

March 22nd letter. 

The TBD notes that nuclear capsules (pits) were stored at IAAP and, according to Appendices 

A and B, were variously stored at Buildings 1-11 and 1-73, as well as in “igloos” in Yard C 

from 1965-1974. Stored pits in sufficient numbers and configuration can yield high radiation 

fields as demonstrated at Pantex in the 1990s during extensive dismantlement of warheads. 

How did NIOSH characterize this source of potential worker exposure and would it not be a 

key contributor to unmonitored dose? Where (in which facility) was the standing pit inventory 

stored at IAAP prior to use of the igloos beginning in 1965? What were the measured 

radiation fields (including maximum measured neutron and photon) in these facilities 

(assuming maximum stored pits in criticality safe array)? Is it possible to identify workers 

whose duties would have included movement of pits into and out of these storage areas? Is it 

possible that these radiation fields (multiple pit arrays) may have exceeded those of single bare 

pit handling, as modeled in the TBD? Did NIOSH review Pantex data on maximum radiation 

field in igloo storage during the 1980s to postulate maximum credible exposure potential at 

IAAP? 

1. Were high facility area radiation measurements (according to site experts, in some areas 

ranging from 12-18 rem/year) verified based on available records and evaluated for 

implications to potential unmonitored worker doses (e.g., to guards assigned to security 

for pit storage areas)? Has NIOSH established whether the “representativeness” of its 

recorded dosimeter readings include workers working in or near such potentially high 

exposure areas? 

2. According to site expert interviews,“flash x-ray” technology was apparently used during 

hydroshots to perform high-speed diagnostic surveys of HE at the moment of detonation. 

Is NIOSH aware of this x-ray application during hydroshots and has it characterized 

potential radiation exposure potentials to workers? 

3. While the presence of large Co-60 radiographic sources and high-energy x-ray units for 

purposes of quality assurance surveying of both HE and nuclear packages is 

acknowledged in the TBD, no characterization of potential radiation fields generated, 

worker practices, or worker exposures are discussed (except to note that they “had the 

potential for producing significant exposure to workers if not used properly”). Did 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

55 of 92 

NIOSH consider worker exposure from these sources to be negligible over time? If so, 

on what basis? If not, why are these routine sources of potential exposure not estimated? 

4. The TBD claims that neutron-photon ratios measured at Pantex in the 1980s-1990s can 

be favorably applied as surrogate values at IAAP, given some of the conservatisms 

included (e.g., wearing of lead aprons at Pantex). However, it is not clear that these 

conservatisms necessarily offset what may be fundamental differences in the radiological 

source terms of the various pit configurations at IAAP during the early years, as 

compared with the more “mature” campaigns handled by Pantex in the later years. The 

presence of U-232, U-233, and other isotopic forms in early warheads, as well as 

differing pit mass (“Hiroshima-sized” pits being the lower bound, not mean), as nuclear 

weapons development proceeded during the 1950s-1960s makes it critical that the “bare 

plutonium” pit model is validated as the hypothetical maximum. Has NIOSH’s 

assessment enveloped these and other considerations? 

5. Site experts indicate that at times the “quarterly maximum” radiation dose was 

approached or exceeded by groups of workers at IAAP in certain operations. Did NIOSH 

find any evidence that this occurred at the site? 

6. Warhead disassemblers would have likely been exposed to potentially higher radiation 

exposure than assemblers, given the aging of plutonium pits (americium ingrowth) and 

additional handling of DU (with increased oxidation and potential resuspension). Did 

NIOSH characterize disassembly of warheads in terms of characterizing potential worker 

exposure under these conditions? 

7. The authors of ORAU-TKBS -0018 Rev. 1 assume that the primary dose contributors 

were from photons and neutrons emanating from an unsealed plutonium-239 “pit” 

weighing 6 kilograms. During the period up to 1962 and beyond, IAAP appeared to be 

involved not only in the assembly, disassembly, and maintenance of weapons in the 

active U.S. nuclear weapons stockpile, but also the development of several nuclear 

weapons in the design, engineering and testing phases. Given these circumstances, IAAP 

may have handled radionuclides which are not considered in the TBD. Based on a 

preliminary review of official unclassified data, we have the following questions: 

• In the early 1960s the Atomic Energy Commission developed and successfully 

tested a device using fuel-grade or “high-burn-up plutonium normally generated 

in a nuclear power plant.1

 Radioistopes of concern include plutonium-240, 

plutonium-241, and plutonium-238.2 The plutonium was provided in sufficient 

quantities by the United Kingdom and from U.S. Production reactors to make 

several weapons.3

 What isotopic distribution of plutonium did NIOSH use in its 

generic pit calculation presented in Appendix D? Are the isotopic distributions of 

1

 U.S. Department of Energy, Office of Public Affairs, Additional Information Concerning Underground 

Nuclear Weapons Test of Reactor Grade Plutonium, December 1993. 2

 U.S. Department of Energy, Non-Proliferation and Arms Control Assessment of Weapons –Usable 

Material Storage and Excess Plutonium Disposition Alternatives, January 1997, pp. 37-39. 3

 U.S. Department of Energy, Defense Nuclear Facility Safety Board, Issue Paper: Plutonium Storage at 

Major Department of Energy Sites, April 14, 1994. 
 

 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

56 of 92 

plutonium available in the classified literature for each of the pits handled at the 

IAAP? If not, did NIOSH evaluate doses for the plutonium isotopic distributions 

characteristic of the full range of potential weapons usable material? Did NIOSH 

verify whether or not IAAP handled reactor-grade plutonium? 

• Radioisotopes, such as americium and plutonium-238, have been used, 

respectively, in neutron and heat generators for nuclear weapons.4,5 Did NIOSH 

verify whether or not workers at IAAP handled components containing these 

radioisotopes and their potential risks? 

• Research and development of weapons fueled by uranium-233 was extensive and 

continuous from World War II to the early to mid-1960s.6,7 When U-233 was 

under development as a nuclear explosive, the major radioisotope of concern was 

uranium-232, which is 60 million times more radioactive than uranium-238. 

U-232 is co-produced with U-233 by irradiation of thorium. Separated uranium233 typically contains 5 to 50 parts per million of uranium-232, which poses a 

significant potential external dose hazard.8 Did NIOSH verify and then consider 

in its dose calculations the possibility of pits containing U-233 at the IAAP, and, 

if so, what range of U-232 contamination was assumed in its calculations? 

ORAU TKBS -0018 Rev. 0, Table 8. (p. 23) indicates that the percentage of workers who 

received monitoring for exposure to external penetrating radiations ranged between 3% to 7% 

from 1962 to 1967, and 14% to 26% from 1969 to 1973. Given the paucity of measured 

exposures, and small number of readings during most of this period, what is the probability, 

including confidence limits, that this relatively small number of monitored vs. unmonitored 

workers is likely to estimate representative missed doses? 

4

 U.S. Department of Energy, Pinellas Plant Facts, GEP-SP-1157, November 1990 

5

 U.S Department of Energy, A Material Management and Disposition Plan for Excess Materials at Sandia 

National Laboratory, Table 1, SAND 2002-1785P, July 2002. P.B-6. 6

 C.W. Forsberg, C.N Hopper, Definition of Usable Uranium-233, Oak Ridge National Laboratory, ORNLTM-13517, March 1998. 7 W.K. Woods, LRL Interest in U-233, DUN-677, February 10, 1966. 

8 U.S Department of Energy, Highly-Enriched Uranium Working Group on Environmental, Safety and 

Health Vulnerabilities Associated with the storage of the Department’s Highly Enriched Uranium, DOE-EH-0525, 

December 1996, pp. 4-5. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

57 of 92 

8. The oxidation and hydriding of exposed metallic fissile materials are well known in the 

declassified literature about nuclear weapons. These have been long standing and 

pervasive problems at all sites producing and handling fissile materials.9,10 The inherent 

instability of metallic plutonium and uranium in the presence of open air and moisture are 

well known to create contamination, inhalation and safety hazards, particularly fires. To 

what extent did the TBD address these issues? 

9

 U.S Department of Energy, Plutonium Working Group Vulnerability Report on Environmental, Safety 

and Health Vulnerabilities Associated with the Department’s Plutonium Storage, DOE-EH-0415, November 1994. 10 EH-0525. 
 

 

 

 

 

 

 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

58 of 92 

ATTACHMENT 2: OUTSTANDING RECORDS REQUESTED OF NIOSH 

TO SUPPORT IAAP SITE PROFILE REVIEW 

April 11, 2005 

Dr. Lewis Wade, Project Officer 

U.S. Department of Health and Human Services 

200 Independence Avenue, SW 

M.S. P-12, Room 715H 

Washington, DC 20201 

Reference: Email from John Mauro to Paul Ziemer and Lewis Wade, dated March 22, 2005, TBD for the Atomic 

Energy Operations at the Iowa Army Ammunitions Plant (IAAP) 

Dear Dr. Wade: 

At the Advisory Board’s request, SC&A, Inc. has been conducting an independent review of the Technical Basis 

Document (TBD) for the Iowa Army Ammunition Plant (IAAP). During the course of this review, we have 

identified the need for documentation that may be in the possession of either NIOSH or the Department of Energy 

(DOE). Some of it may be classified, so it is possible that all or portions of this documentation may prove to be 

available at the April 12, 2005 classified review to be conducted in conjunction with the Advisory Board at the DOE 

Germantown facilities (while we are in receipt of an agenda for the review, we have not seen an inventory of 

documents to be made available). 

In our March 22, 2005 correspondence, we requested documentation (as a supplement to the questions submitted by 

SC&A) that NIOSH likely possesses. This documentation, which has not yet been forwarded, includes the 

following: 

• “TOP Hat” Database to review recorded interviews conducted by NIOSH of IAAP workers 

• Access to the number of workers monitored to match the numbers of dosimeters referenced in 

Table 6.4, Revision 1 

• Copies of documentation reporting the 15 incidents that involved radioactive materials cited in 

Appendix E 

SC&A also requires access to additional data other than that currently available through the NIOSH site profile 

research database. This information, which may or may not be classified, and may or may not be available for our 

review on April 12, 2005, is necessary to properly evaluate likely historical exposure conditions and the 

appropriateness of theoretical models. We request available documentation related to the following topics: 

• Radionuclide constituents of the pits handled 

• Size and shape of pits handled 

• Radiological survey data (contamination and radiation surveys) 

• Historic practices (e.g., number, configuration, number of support personnel) for storage of 

nuclear weapons or nuclear weapons components 

• Release or spread of radioactive contamination to the environment 

• Landauer film badge design and calibration procedures. 

Pursuant to the existing HHS/DOE memorandum of understanding on site records access, we are requesting the 

following IAAP documents which, based on site expert interviews, we believe may be available from DOE: 
 

 

 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

59 of 92 

• Health and Safety Procedures 

• Radiological survey, air sampling, and internal monitoring data 

• Documentation on early Landauer film badges (Landauer indicated this information was provided 

to NIOSH) 

• Production Procedures 

• Pantex Box #291 (contains receipt logs for Oy and Pu, tear down logs for Oy and Pu, personnel 

shielding information, radiation safety correspondence) 

• Pantex Box #366 (contains radiation safety correspondence, effluent and environmental 

monitoring data, nuclide inventory data) 

• Pantex Box #186 (contains information on atomic weapon nuclear safety studies and surveys, 

storage and transportation requirements, handling of raw materials and containers) 

• Pantex Box #389 (contains information on AEC accident experience, radiation safety 

correspondence, and supervisor reports of accidents) 

• Pantex Box #367 (contains information on the Hydroshot and Firing Site operations and 

decontamination) 

• Pantex Document #318012, Landauer and Tracelab Radiation Dosage Reports - Film Badges on 

Burlington Plant Employees 1956-1962. 

• Inventory of all IAAP records stored at Pantex 

• Information on Burning Field and Firing Site operations, including destruction of documentation 

• Access to the document repository of IAAP-related records referred to in the Work Plan for 

Supplemental Remedial Investigation of Line I (Including Historical Site Assessment) Iowa Army 

Ammunition Plant Middletown, Iowa prepared by TN & Associates, Inc. 

• Transcripts or notes from the July 29, 2004 worker outreach meeting in Burlington, Iowa 

• Supporting records provided by Special Exposure Cohort petitioners 

SC&A understands that some of these documents may be classified and require secured access under the MOU. 

These records are needed to allow us to effectively evaluate the site profile. Any assistance you can provide would 

be appreciated. Feel free to contact me at (732) 530-0104, Joe Fitzgerald at (240)-422-9115, or Kathryn RobertsonDeMers at (509)-460-9005 if there are questions or concerns with regard to this request. 

Sincerely, 

John Mauro 

Project Manager 

cc: Paul Ziemer, Chairman, ABRWH 

Board Members, ABRWH 

Joseph Fitzgerald, SC&A 

 Kathryn Robertson-DeMers, SC&A 

Project File: ANIOS/001/09 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

60 of 92 

ATTACHMENT 3: CONFERENCE CALL WITH NIOSH AND SC&A 

Attachment 3 is not provided at this time, because the transcripts of the conference call have not 

yet been issued by NIOSH. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

61 of 92 

ATTACHMENT 4: IAAP FACILITY SITE EXPERT INTERVIEWS 

Over the course of the audit on the Iowa Army Ammunition Plant (IAAP), Kathryn RobertsonDeMers and Joseph Fitzgerald have had an opportunity to interview a number of site experts. 

Site experts included individuals involved in production, inspection, security, and safety and 

health. Also interviewed were members of the Burlington Atomic Energy Commission Plant— 

Former Worker Program at the University of Iowa. 

The information the site experts provided has been invaluable in providing us with a working 

knowledge of operations occurring at the IAAP. Site experts provided a baseline understanding 

of working conditions and the extent of the safety program through time. This information was 

utilized to further identify critical vertical issues. The information provided in these interviews 

helped SC&A obtain a comprehensive understanding of the radiological risk at the facility. 

Information regarding the security and production operations at IAAP is provided in Part 1. An 

interview summary related to the safety program is included in Part 2. These interviews were 

conducted via teleconference from March 21 to April 14, 2005. The information provided is not 

a verbatim transcript, but a summary of information collected from all interviewed experts. 

Individuals have provided this information based on their personal experience. It is recognized 

that these recollections and statements need to be further substantiated before being adopted in 

the Technical Basis Document (TBD) (ORAU 2005). However, they stand as critical 

operational feedback where records and other documentation are lacking or unavailable. This 

interview summary is provided in that context; site expert input is similarly reflected in our 

discussion and, with the preceding qualifications in mind, has contributed to our issues. 

Part 1: Security and Production Operations 

Many of the operations and processes at the IAAP are deemed classified, therefore limiting the 

content of the interviews. Workers were told when they began work at IAAP that they were not 

to discuss their work outside the immediate work areas; otherwise criminal charges would be 

brought against them. Many of the site experts were concerned about classification issues and 

company retribution, further limiting the interviews. Topics that could not be discussed during 

site expert interviews included the following: 

• Size, weight and shape of weapons components 

• Type of special nuclear material shipped to IAAP 

• Radionuclide and chemical constituents of weapons components 

• Details of the assembly, disassembly, and retrofit processes 

• Details of tritium shipments, including the containers it was shipped in 

• Storage of weapons and/or weapons components 

• Number of weapons and/or weapons components stored in an area 

• Classified documents 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

62 of 92 

Facility Description 

IAAP involved two distinct operations from 1947–1975. Division A was run by the Army and 

was involved in the production of various conventional weapons (i.e., shells, detonators, mines, 

etc.). Division B was run by the Atomic Energy Commission (AEC) and was involved in the 

assembly, disassembly, repair, and retrofit of nuclear weapons. AEC took control of Line I, the 

burning fields, and test firing in 1947. They started modifications to Line I. AEC had the 

ultimate authority over operations on Line I and used on-site supervisors, inspectors, and plant 

managers to monitor work performed. Operations began in 1947 and continued to mid-1975. 

The Army eventually took control of this portion of the plant after AEC left. 

The plant has been known by a number of names, including the Iowa Ordnance Plant (IOP), the 

Burlington Atomic Energy Commission Plant (BAECP), the Iowa Army Ammunition Plant 

(IAAP or IAAAP), and the American Ordnance Plant. The IAAP mission was to fabricate high 

explosive (HE) components for nuclear weapons and to assemble, disassemble, and repair 

nuclear weapons. Division A produced ordinance munitions. Site experts did not know the 

exact date fissile material arrived onsite. 

The plant included buildings dedicated to various functions involved in assembling and 

disassembling weapons. The buildings were numbered, based on which division the operation 

supported. Buildings with the leading number of 1 indicate that the building was associated with 

Line I operations. Table 1 lists some of the buildings associated with Division B work and the 

general activities that occurred in those buildings. 

Several buildings were involved in the handling and storage of radioactive materials including 

1-11, 1-12S, 1-13, 1-61 series, 1-63 series, 1-77, C Yard, and the Firing Site. Building 1-100 

housed the x-ray units and sources used in radiography. There were several areas on Line I that 

did not handle radioactive material. These areas included the tool and dye shop, the machine 

shop, the wet chemistry lab, HE processing, and the melt process. 

Several programs were occurring at the facility at a given time. As a result, the process of 

weapons assembly and disassembly occurred in different locations on Line I. In general, 

different weapons were assembled in different areas. Assembly operations started in Building 

1-13. In later years, retrofit and repair were added to the list of operations in Building 1-13. 

Once additional assembly buildings were completed, the operation was moved to these buildings. 

Building 1-12S, series 1-61 buildings, and series 1-63 buildings were involved in assembly and 

disassembly work. The explosive powder was removed from the weapon in Building 1-12S. 

Buildings 1-12N and 1-40 were the machining areas. 

Assembly occurred early in the operations of Line I, whereas disassembly operations started at a 

later date. Site experts could not identify a change in operations that would distinguish the pre1962 period from the post-1962 period. Production was fairly steady until the 1970s. 

“The Melt” (Buildings 105-1 and 105-2) manufactured HEs. Raw materials were melted down 

and poured into molds. The finished mold was then machined to the appropriate tolerance. 
 

 

 

 

 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

63 of 92 

Table 1: Buildings and Areas Associated with AEC Operations at IAAP 

Building Description of Operations 

1-01 A production office before 1-52 was built. Locksmith and trades were there in later years. 

1-04 Production offices, Safety offices, Maintenance and Administrative services, Chem Lab, and 

sciences 

1-10 Storage area 

1-11 Tritium reservoir and pit storage. Offloading of RR cars with raw materials. 

1-12 (main) Machining and pressing of HE into balls; 2 MeV X-ray Unit 

1-12N Machining and pressing of HE 

1-12S Disassembly area for pits and HE 

1-13 Assembly area; Retrofit; Disassembly. Major disassembly use: broken HE balls, vacuum pump 

pinch off tubes. 

1-18 Research and Development 

1-19 General storage area 

1-40 Underground; machining operations 

1-50 Storage of raw material for “The Melt”; movement between conveyor belts to 105-1 or 105-2 

1-51 Assembly of packages in weapons. Electronics and Non nuclear. Controlled temp and humidity. 

1-52 Production offices and maintenance 

1-55 Production offices in 1960’s. Large vaults for codes and papers. Main Guard access for trucks and 

vehicles in/out line. 

1-61 Assembly of different programs, including spheres and HE; MOCA was used here. 

1-63 Series Underground Gravel Gertie containing assembly areas with operating bays. 1-63-5 contained a 

touch up bay. 1-63-7 was used for storage of completed weapons. 

1-65-6 Out-loading of weapons. 

1-73 Inspection, weighing, and swiping of pits 

1-77 Inspection, weighing, and swiping of pits; storage area (built in later years); tritium-related 

production. 

1-80 

1-85-2 Believe to be used as load out of weapons. 

1-100 Series These buildings were built for x-ray use. There were x-ray units (2 MeV) and a small HE 

machining operation. 

1-105-1 Melt Facility 

1-105-2 Melt Facility 

1-106-1 Formulation of material for “The Melt”; put boxes of HE on conveyor for transport to 108-1 

1-106-2 Formulation of material for “The Melt” 

1-107 Underground; storage area for HE 

1-108-1 Screened for foreign material that could cause sparking. 

1-148 or 1-160 Tool and Die machine shop, built in mid 1960’s 

Area between 

1-11 and 1-77 Venting of tritium reservoirs 

1-137-4 Line I Cafeteria. Open to entire plant, AEC and the Army. 

Yard B 

a.k.a. Burning field “B,” east of Line I, north of Yard “C” 

Open burning of explosives, parts and pieces, papers relating to old weapons. Defective HE and 

scrap. 

Yard C Finished products and pit storage for disassembled weapons (Igloos); loading and unloading of 

completed weapons. 

Yard L Shipping and receiving of components; non-nuclear components storage. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

64 of 92 

There were also electronics and machine shops, support laboratories, and an administrative area. 

Building 101 housed the Maintenance Department. This included a machine shop, electric shop, 

and pipe shop. The machine shops were responsible for machining HEs. 

There were three laboratories associated with Line I operations, including a main laboratory, an 

electronics laboratory, and a chemistry laboratory. Laboratories on Line I produced necessary 

mixtures for production processes, provided analytical support, and performed work on weapons 

and/or weapons components. Some were involved in Research and Development (R&D) 

operations, including development of improved methods for initiation. 

Workforce 

In general, individuals worked for either Division A, which was responsible for conventional 

explosives, or Division B, which was involved in AEC work. Although Army and AEC 

personnel worked at the same facility, the production and support workforce was not 

interchangeable between the two operations. The workforce at IAAP was allowed to move 

between Division A and B if appropriate clearances were in place and there was a position 

available. This required changing employers. Security was responsibly for overseeing 

operations in both Division A and Division B, and could be rotated between the two divisions 

based on their assigned duty station. Thousands of workers (5,000–10,000) worked at the IAAP 

facility for either the AEC or the Army. 

Sections of the work force on the IAAP site were mobile, while others were static. Individuals 

would bid on different jobs. At times individuals were assigned to other jobs. There was also 

movement between shifts. 

Typical work shifts were 8 hours per day. IAAP operated 24 hours per day, 7 days per week. A 

typical workweek was 40-50 hours. Depending on the particular job, there were one to three 

shifts. The company had what was referred to as “Peg Points.” A Peg Point was a production 

goal that had to be met on a periodic basis. As the time to meet these goals approached, there 

was an increase in production. Workdays were extended to 10–12 hours per day up to 7 days per 

week. One site expert estimated that over the course of a year, there was an average of 10–20% 

overtime for the production workers. Specific workers were also called in during emergencies, 

due to their skills. Safety personnel periodically had to work overtime to receive a shipment. 

During one period of time, production workers went out on strike. As a result, supervisors were 

asked to perform assembly and disassembly to allow the company to meet its goals. 

Upon closure of the AEC operation at IAAP, numerous (>100) employees (e.g., engineers, 

managers, and supervisors) transferred to the Pantex Plant. Site experts do not recall individuals 

transferring to Mound. 

Security 

The contractor (Mason & Hanger) maintained Physical Security for both the Army side and the 

AEC side. Over 200 persons were used 24 hours per day, 7 days per week on three shifts to 

supply security. Security’s responsibilities were similar to that of city law enforcement. In 

addition to general law enforcement duties, security was responsible for traffic control, fire 

patrols, and physical security of the yards, production lines, and other buildings. They were also 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

65 of 92 

trained as Emergency Medical Technicians (EMTs) for the purposes of emergency response. 

The guard headquarters ran the ambulance service for Division A and Division B. Security had 

to deal with everything from family fights to drunks to explosions to injuries. Then there was the 

radiation. 

Access to the facility was controlled with the use of an identification badge. The ID badge was 

constructed in the standard dimensions with a photo of the wearer in the center. Numeric values 

(i.e., 1–6) were listed on the badge. These numbers corresponded to specific areas in Line I, C 

yard and L yard. Individuals were allowed to enter only those areas corresponding to the 

numbers on their badge. The ID badges were also color coded to illustrate whether individuals 

were from the Army or AEC portion of the plant (i.e., blue and green were used for the Army 

and AEC, respectively). Additional colors were used to indicate government or contractor status. 

Guards would verify the level of clearance an individual had prior to entry into an area. 

Personnel dosimeters were not integrated into the identification badge; however, criticality 

accident dosimetry (i.e., indium foil) was added in later years. The security badge exchange 

posts maintained a record of individuals entering and exiting the areas. 

The operations were compartmentalized such that the workers had only knowledge of the 

particular job they were involved in. Workers were directed not to discuss their work outside 

their immediate work area. 

Security guards would report to guard headquarters on their assigned shift for inspection and 

assignment of firearms. Shift hours were 7 a.m.–3 p.m., 3 p.m.–11 p.m., and 11 p.m.–7 a.m., 

7 days per week. There was a formal turnover between shifts. Duty stations were assigned that 

could include work in either Division A or Division B. Security personnel were allowed to “bid” 

for or trade duty stations. Individuals who did not have a clearance were required to work on the 

Division A side. Some of those with Q-clearances did not like to work in Division B because of 

the health concerns related with the work. 

Guards had regular tour assignments to verify materials were in the appropriate locations and 

there were no unauthorized entries into areas. Specific duty stations included the following: 

• Manning badge exchanges 

• Working in two-man teams among weapons and storage areas 

• Mounted patrols roaming the local area 

• Walking tours of Line I 

• Driving tours of the facility boundary 

A Detex clock was used to verify that the guards assigned to tours performed all checks required 

of the duty station. Security verified seals on doors and windows, and inspected general areas. 

For AEC, there was a mounted patrol both inside and outside the interior fences around Line I 

and associated storage areas. Foot patrols were used from the time day shift production workers 

exited until they returned to the line. Security personnel were rotated through various tours. 

There were over 200 guards assigned to security between the AEC and Army operations onsite. 

About 25 security personnel were assigned to work supporting AEC operations. During the day 

shift, more than 40 guards were assigned to AEC operations. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

66 of 92 

Some duty posts involved touring multiple buildings, while others required surveillance of 

specific areas. The interior and exterior of the buildings, rooms within buildings, and materials 

had to be inspected periodically (e.g., every 30 minutes for some areas). Guards had to verify 

that material was present and that no authorized entries had been made into the area. They 

walked around the weapons and/or weapons components to ensure everything was in its place. 

The distance between the guard and the contained nuclear material ranged from direct contact to 

several yards. 

Security was responsible for guarding special nuclear material and weapons. Access to both 

coded vaults and vaults containing actual weapons or parts was controlled. If individuals were 

guarding access to vaults that contained weapons, the job required the use of the buddy system. 

There were high-security combination locks on the data and code vaults. In addition, there was 

key control over these areas. Each individual of the two-man team had a key. Both keys were 

necessary to access these areas. One guard would lock the other guard into the area. There were 

seals placed across the door that had to be removed and logged with each entry. Upon leaving 

the area, a new security seal was placed across the door. The tours required guards to work 

among the weapons for a full shift. Guards were assigned to these areas for variable periods of 

time ranging up to 40 hours per week in some cases. There were also periods of time when there 

was substantial overtime. At times the guards were required to stand immediately adjacent to the 

material. Some guards reported feeling weak during and after these types of job assignments. 

Security guards reported that on these tours, the hair on their arms stood on end. When this 

occurred, the guard gave the weapons a lot of space to prevent this from recurring. 

The reference to a vault must be clearly defined when discussing Security guarding weapons and 

weapons components. These vaults were similar to bank vaults. This does not refer to the 

Igloos. The guards’ job was to stand watch and make sure materials did not leave the vault. The 

weapons and weapons components had to remain inside. 

There were no signs posted on containers that identified the contents. Guards did not have a 

need to know what they were guarding. 

Logs were kept to document any security infractions. If a guard identified problems, such as 

something being out of place or a security infraction, they were to notify guard headquarters 

immediately. Headquarters would determine follow-up actions related to the incident. An 

incident report was generated for each occurrence and reviewed by a lieutenant. How effective 

this process was is questionable. They were reviewed and most ended up being discarded in the 

trash rather than provided to higher-ups. Some security guards remember seeing these reports in 

the trash. Some workers have postulated that unless the incident was serious, it was not formally 

documented. There is a concern that security incident reports were hushed due to the reduction 

in awards fees and bonuses associated with security infractions. In addition, some security 

employees felt individuals making waves were assigned to less desirable duty posts. In some 

cases, guards maintained personal notes, which were later confiscated and burned. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

67 of 92 

Material Shipping and Receiving 

Security held the joint responsibility with AEC couriers for the procurement of components used 

in the assembly of weapons. The details of these transactions are classified and could not be 

discussed. Weapons components were shipped in and out via railway, truck, and airplane. 

Weapons components were shipped in and out of the plant on a continuous basis. Enough 

components were maintained onsite to keep production going. An AEC courier accompanied 

material shipped onto the site. This was to assure everything was proper and accounted for prior 

to receiving (sometimes referred to as buying) the material. A mass balance inventory of 

received and shipped nuclear components was maintained. Components were received from the 

Y-12 Plant, the Savannah River Site, and the Rocky Flats Plant. Los Alamos National 

Laboratory (LANL) and Sandia provided engineering support to the facility. 

Security commanders had the responsibility of meeting, inspecting, and receiving shipments of 

material from couriers. They were the first to enter the transport vehicle just inside the perimeter 

fences. Pits were received in white barrels like 55-gallon drums, each placed on a wooded skid. 

Tritium was inside JP containers (i.e., pressurized containers). Security performed a physical 

search of each barrel or container and compared the serial number of each to the manifest. This 

required the commander to climb on and around the containers on the transport vehicle. This 

process took from 30 minutes to an hour. Once completed, the commander accompanied the 

shipment to Building 1-11 or 1-77. At this point, the material was in a secured area. Security 

was not required to escort the nuclear material within the secured area. 

Safety personnel would perform contamination and radiation surveys in and around the transport 

vehicle. Swipes were taken on the packaging of material shipped. Safety personnel wore 

coveralls and booties upon entry into the transport vehicle. Security personnel were not provided 

with personnel protective equipment to perform the initial inventory check. When the surveys 

were completed, production control or stores operators would move the shipment to the storage 

facility. Some commanders were upset by the fact that they were required to enter the railcars or 

trucks prior to survey by the Safety Department. 

Company inspectors were required to perform “weight” checks of the pits upon receipt at IAAP 

in Building 1-73 or 1-77. This inspection of the pits involved weighing them and recording the 

results. Production control would remove up to 10 pit container lids in the storage area at one 

time. Safety would perform contamination surveys on a subset of all the pits inspected per day. 

Two containers were taken to the inspection area. Inspectors would remove the pit manually 

from the container and place it on a scale, where it was weighed. The scale had a see-through 

sliding glass door, which was closed after the pit was placed on the scale. The pit was removed 

and put back into the container and the next pit removed for weighing. The two containers were 

opened, exposing the pits at the same time in the inspection area (i.e., approximately 15 ft x 15 

ft); however, only one pit was out of its container at a time. This process was repeated for the 

entire shift. Reservoirs were also weighed. 

There were one or two shipments received from Oak Ridge that had some contamination on 

them. The Safety Manager was sent to Oak Ridge to resolve this situation, as they were 

concerned the material would have to be returned to Oak Ridge. Contamination was believed to 

be depleted uranium. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

68 of 92 

Following survey and receipt of shipments, units were either put into storage or shipped directly 

to the production line. Site experts do not recollect receiving “special shipments.” 

Couriers were cognizant of containers that posed some type of problem (e.g., damaged units, 

high dose rates, leaks, etc.). They would inform Security which units were causing a problem. 

Damaged material was separated and sent directly to Building 1-13. Some of these units came 

from Pantex to IAAP for rework. Ultimately they were sent back to Pantex. 

Assembled weapons were shipped to other AEC facilities. The reverse process was performed 

when items were shipped out. When weapons or components were shipped by airplane, Security 

had to escort the material to the airport and remain there until the airplane took off. 

Storage of Weapons and Weapons Components 

Pits were shipped to IAAP as individual units. They remained in storage until they were needed 

for assembly. The length of time the finished units were stored at the facility varied based on the 

availability of transportation. Some units stayed in the storage area for an extended period of 

time, while others were shipped right out. Capsules and pits were stored in Buildings 1-11 and 

1-77, and later 1-73. Finished weapons were stored in the Igloos in Yard C. Some site experts 

indicated that completed weapons were stored outside under tarps prior to placement in the 

Igloos. 

When the weapons or components were worked on, they were moved to Line I. There were 

several storage areas on the production line. Units could be stored in the bays for 24–48 hours, 

making them immediately available. The quantity of HE allowed in the area at one time was 

restricted. This limit was posted in the immediate area as a reference for workers. 

Storage areas were designed to prevent criticalities. There were boxes painted on the floor in 

Buildings 1-11 and 1-77, which were designated for storage of materials. The metal boxes in 

which the pits were stored ensured proper spacing during storage. The storage configuration 

varied with the storage facility. Criticality prevention specifications (i.e., spacing, inventory) 

were not consistently applied across the various operations and throughout the period of AEC 

operation at IAAP. 

Weapons Production 

IAAP was the first plant of its kind involved in the final assembly of nuclear weapons following 

the on-site manufacture of explosive components for each weapon. Numerous types of weapons 

were assembled and disassembled at the site over time. The exact contents of the subassemblies 

were dependent on the type of weapon. There was a notable difference between the assembled 

and disassembled pits. Weapons produced at the site supported military involvement in Korea, 

Vietnam, and the cold war. Site experts identified Mark 6, Mark 28, and Poseidon missiles as 

some of the units worked on. If the worker did not have a need to know, the worker was not told 

the details relating to the material handled. Even the radionuclide constituents of the particular 

pits were not communicated to the workers. Workers noted that smaller units generated more 

heat. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

69 of 92 

There were multiple programs occurring at the same time during operation. The weapons size 

and components varied over time. The time it took to assemble a weapon varied based on the 

type of weapon. 

Standard Operating Procedures (SOPs) were used to guide the assembly and disassembly 

process. There were different procedures for different weapons. The specific SOPs contained 

details processes associated with a specific weapon type. Although there was no formal 

criticality safety program, specifications for storage and inventory limits were included in SOPs. 

The number of individuals working in a particular job assignment at a particular time depended 

on the operation and the shift. During the day shift, approximately seven to eight individuals 

were assigned to each cell during assembly. This group of individuals included AEC personnel, 

inspectors, operators, and production control. Assembly and disassembly areas housed 

numerous bays, depending on the building. Some operations were not performed during swing 

and graveyard shifts, so a smaller population of workers was at the facility during this time. 

IAAP manufactured HEs for use in weapons. This involved melting, pressing, and machining of 

HEs. Raw materials for HEs were melted in a kettle and mixed with chemicals. The “melt” was 

poured into molds to shape the HE shells. Various explosives (e.g. HMX, RDX, PETN, and 

other exotics) were used in the development of initiating systems. Once formed, the HE shells 

were machined. The beryllium shells within the HE hemispheres were also machined. 

Assembly operations were performed in Gravel Gerties, which were covered with about 40 ft of 

dirt. These were designed to implode if an explosion occurred. Groups of workers were 

assigned to an assembly area. Two or more individuals (i.e., more individuals required for 

disassembly) worked on one or more units within the same assembly area (i.e., Gravel Gertie). 

In other cases, there was more than one team in the same assembly area working on separate 

weapons. Weapons were assembled in stages. Each stage had to be inspected by an AEC and a 

company inspector. These assembly inspections took variable amounts of time, depending on 

the particular stages and the availability of inspectors. Each individual was responsible for 

making sure each stage was completed correctly prior to the inspection process. 

The nuclear package consisted of a pit, a HE hemisphere, and a beryllium shell, which fit 

between the pit and the HE. The HE hemispheres were manufactured at the Burlington Plant. 

The pits arrived at the facility already machined. The radioactive constituents of the pit were 

enclosed in a sheath. Beryllium shells were glued into the HE hemisphere. The pit was 

positioned in the bottom hemisphere of the HE. It was manipulated manually or with the use of 

an air-operated hoist and clamping device. The pit had to be carefully lined up in the 

hemisphere. Adhesive was placed on the hemisphere and the pit, and the top hemisphere was 

sealed to the bottom hemisphere. Some production workers would also add adhesive to the 

lower hemisphere to ensure the unit stayed intact. 

There were various phases of weapons assembly and disassembly that required direct contact 

with radioactive material. Workers had to bend over the pit in the bottom part of the hemisphere 

to pick the top of the sphere off the floor. This resulted in exposure of the face and pelvic area to 

the radiation field. Sometimes they had to hold the hemisphere against their body. Other times 

the materials were handled within the spherical casing. Workers were provided with cotton 

gloves, as they were not allowed to get body oil on the pit. 
 

 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

70 of 92 

The time workers were in the immediate proximity of the pit (i.e., within 1 m) varied by the 

program, the skill of the particular workers, the quality assurance process, the number of units 

processed per day, and the number of units in the immediate area. Based on this site expert 

feedback, the implication of the work factor derived by the National Institute of Occupational 

Safety and Health (NIOSH)─that individuals were within 1 m of the pit for about 1 hour per 

day─is apparently not consistent with the actual operations at IAAP, as directly experienced by 

some production workers. 

The production control group was responsible for transportation of components and finished 

weapons. Forklifts were used to move material between the production line and storage. Cranes 

were used for numerous operations, including movement of weapons components, placing items 

into the weapon, and loading railcars. Other production control duties involved performing 

inventories on nuclear items. These inventories were performed monthly. Two-man teams were 

responsible for comparing numbers on the containers to serial numbers on a master list. During 

these duties, they were among the nuclear components. 

Disassembly, repair, and retrofitting were also performed at IAAP. The purpose of the 

disassembly of weapons (sometimes referred to as teardown) was to salvage portions of the 

weapon that could be reused and to destroy the remainder of the weapon. The pit was one 

portion of the weapon that was recovered and eventually shipped to other AEC facilities. 

Disassembly was the reverse of the assembly process. High explosive hemispheres and any 

inner beryllium shells had to be removed from the pits. Following the initial attempt to remove 

the hemisphere and associated shells from the pit, residual adhesive and HE was left on the pit. 

Pits had to be returned free of adhesive. The pits were soaked in a bath of acetone and the 

residual material was scraped off the pit. At times the liner would separate from the HE, but 

remain fixed to the pit. This made it more difficult to remove. When the use of dry ice began, 

the disassembly process became easier. The clean pit was shipped off site for storage. The 

remainder of the unit was sent to the burning field. Weapons disassembled at IAAP included 

weapons assembled at the Pantex Plant. 

Retrofit involved rework on units already assembled. This was a limited operation. Some of the 

units requiring retrofit were sent from Pantex. Repair activities included removing chips 

produced by machining in the HE. Weapons repair in the HE section was completed by 

Weapons Repair men. They used melted HE material to repair nicks in the HE hemisphere. A 

Weapons Specialist was available to assist during assembly when things were not working quite 

right. 

Appendix B of the TBD outlines the assembly and disassembly dates for various weapon types at 

IAAP. This list appears to accurately reflect the operations at IAAP. 

Other Operations 

Radiography sources included a Co-60, flash x-ray units, and other x-ray units. Laboratory staff 

was involved in developing improved methods for initiation. The laboratory analyzed various 

explosive materials and metals. Staff worked with flash x-ray units, open x-ray diffraction units, 

and radioactive sources. These sources were used as a replacement for the x-ray machines. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

71 of 92 

Radiography was primarily performed on HEs; however, warheads were also examined on 

occasion. The x-ray units were used to examine HEs for cavities and cracks. Cobalt-60 was 

used occasionally to radiograph completed weapons. The Co-60 source was maintained in a 

huge lead pit. Radiography operations were conducted in the x-ray vaults, which had a double 

interlock system. 

X-ray unit inspections were periodically performed by equipment operators. Periodically, Safety 

conducted surveys on radiography systems, including checking the interlock systems. Shielding 

was provided around the x-ray machines to reduce exposure. When using the flash x-ray unit, 

personnel were 50 yards away in an underground area behind 3–4 ft of concrete. 

The flash x-ray units were used during hydroshots to perform high-speed diagnostic surveys of 

HEs at the moment of detonation. Flash x-rays had to travel through steel and/or explosives 

requiring energetic photons. Explosives were used to drive a conductor through a magnetic field, 

creating high energy x-rays necessary to penetrate the material. 

Although much of the weapons design work was done at Sandia, LANL, and Lawrence 

Livermore National Laboratory (LLNL), IAAP personnel were directly involved in resolving 

issues related to designs. Some engineers traveled to these sites to consult with weapons design 

staff. R&D was conducted on HEs materials and components. They were attempting to make 

smaller weapons. This work did not involve use of radioactive material containing Pu-239. 

Personnel designed improved equipment for use in the manufacturing and assembly process. As 

a result of these activities, visiting engineers came from other facilities to oversee design work, 

and to observe the use of newly designed equipment. 

Burning Fields 

The burning field was located east/northeast of Line I and approximately 2 miles from the plant 

boundary. Materials (e.g., tools, pipes, tile, etc.) coming out of Line I that were not shipped off 

site were taken to the burning field. For example, if a weapon was taken out of service, the 

weapon was broken up, and the pit and other valuable material (e.g., gold and silver) was 

removed. The remaining components were taken to the burning field. That included even the 

papers and documents that referred to that specific weapon. Guards recalled having to escort 

documents to the Burning Field for destruction. They were required to stay with the documents 

until the process was completed. Materials were crushed if necessary, flash-burnt, and buried. 

Burning field operations involved open burning. Fires were lit remotely, after which individuals 

would go to an area about 0.5 mile away. 

Test Firing (Hydroshots) 

Test firing of units with depleted uranium was performed from 1965–1974. There were a total of 

701 hydroshots. A total of 8,500 lb of depleted uranium was destroyed in hydroshots. In 

addition, regular HE detonations were performed during this period. 

Material to be tested was compiled in FS-5 or what is referred to as the Make Up Bay. Pin bugs, 

used to monitor parameters of the detonation, were glued into the hemisphere. The unit was 

taken to the firing site for set-up. Cables were lowered down into the FS-12 tunnel and plugged 

into the detonator lead. The set-up crew would go to a safe area (approximately 2 city blocks 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

72 of 92 

away). A siren would sound warning individuals test firing was occurring. The hemisphere was 

then detonated. A camera filmed the detonation. There were a couple of “special shots” per 

month that used flash x-ray. The force of the explosion drove the molten metal 0.5 inch into the 

neighboring steel-plated building. Occasionally, the detonation would cause fires in nearby 

timbers outside the fire break areas. Some site experts reported seeing a glow on the lake 

following hydroshots. 

Following the hydroshots, a crew of men was required to retrieve large chunks of metal. Both 

large remnants and fine particles resulted from the explosion. Large pieces were retrieved using 

either bare hands or cotton gloves. Geiger counters were used in some cases to help locate these 

large pieces. This material was marked as radioactive material and forwarded for disposal. 

Personnel were required to access the FS-12 tunnel to set up detonations and recover materials 

from previous detonations. 

During the remediation of the site, 35 lb of depleted uranium was found in the soil. This area 

was cordoned off and personnel, even the mowing crew, are not allowed into the area without 

authorization. This prevented disturbance of the depleted uranium, which may still be present at 

the site. 

Production Records 

All records related to AEC activities were shipped to Pantex when the operations at IAAP 

ceased. Mason & Hanger was sold and no longer exists. No records are known to be stored at 

the corporate headquarters in Lexington, Kentucky. Some of the contents of the records 

available at Pantex include air monitoring data, area dosimeter readings, beryllium air 

monitoring data, accident investigations, and administrative procedures. 

One site expert was formerly employed at Pantex and had the opportunity to review records at 

Pantex relating to the Burlington operations. The review of these records was required, due to 

requests submitted for worker records and incident investigations. Epidemiology groups also 

have requested records, including personnel monitoring records, air monitoring, and radiation 

survey data. There are a few hundred boxes of records relating to the Burlington plant located at 

Pantex. Many of the records are classified. The records were shipped from Burlington and 

automatically put into a Q-cleared storage area. The records have not undergone formal 

classification review. 

Comparison of IAAP and Pantex 

Pantex and IAAP received two different weapons designs. Pantex worked primarily on weapons 

designed by LLNL. IAAP worked primarily on weapons designed by LANL. This indicates that 

the source term for the two facilities was not identical. Pantex had a similar mission to IAAP; 

the two were considered sister plants. The facilities were also similar in design. When both 

facilities were in operation, some weapons and/or components were passed back and forth 

between the plants. Items received from Pantex primarily required retrofitting due to what site 

experts refer to as poor craftsmanship. Pantex eventually took over the work performed by 

IAAP. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

73 of 92 

The processes implemented at IAAP varied from those implemented at Pantex. Each plant had 

its own interpretation of instructions and best practices. In general, the types of radiation hazards 

associated with the two facilities were the same from 1951–1975. Operations at both plants were 

primarily manual. 

Chief engineers and scientists had the opportunity to visit Pantex, LANL, and LLNL (known at 

the time as Lawrence Radiation Laboratory) on a regular basis. During their visits to Pantex, it 

was observed that the facility had a better safety program than IAAP. For example, Pantex 

issued dosimeter badges to all individuals entering radiation areas. It was also noted that there 

was tighter control over the dosimeters. At Pantex, workers were provided with lead aprons; 

whereas at IAAP they were not. Worker proximity to the radioactive material also differed at 

IAAP and Pantex. 

NIOSH used the Pantex film badge data from 1993–2003 to determine the neutron-to-photon 

ratios for IAAP. There is considerable concern among site experts, including safety personnel, 

regarding the use of these data as a surrogate for IAAP. One former worker of both facilities 

stated that comparing neutron exposure during the 1950s, 1960s, and 1970s at IAAP with that 

from Pantex in the 1990s is not valid. There were two reasons stated: 

1. Weapon systems were very different 

2. Processes were different, i.e., shielding process times were shorter at Pantex in the 1990s 

due to weapon design; therefore exposure was different 

Army Plant Operations and Incidents 

Many individuals were killed in accidents at the plant in Division A. Incidents primarily 

involved explosions and exposure to chemicals. Guards at times had to remove corpses or 

portions of bodies from accident areas. Some of the specific incidents that occurred at the plant 

included the following: 

• An explosion in a powder room, which killed a woman 

• Explosions resulting in loss of hands or portions of hands 

• An explosion of a detonator, which resulting in shrapnel being propelled into a woman’s 

leg 

• Loss of consciousness from chemical exposure 

Tetryl, a yellow powder, was used on Line 5B. People that worked with tetryl had their skin, 

hair, and the whites of their eyes turn a yellowish-orange tinge. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

74 of 92 

Part 2: Health and Safety Program 

As previously mentioned, interviews were conducted with a number of site experts, including 

former workers in production, inspection, test fire, security, and safety and health. Also 

interviewed were members of the Burlington Atomic Energy Commission Plant—Former 

Worker Program at the University of Iowa. The information provided is not a verbatim 

discussion, but is a summary of information collected from all experts interviewed. 

Although many of the details of the operations and processes at the IAAP are deemed classified, 

it is evident that health and safety program information is not. This information is summarized 

separately in an effort to keep worker input intact. 

General Information 

Mason & Hanger were responsible for the safety program. The safety department was 

responsible for providing industrial safety, industrial hygiene, radiation protection and 

environmental monitoring support to Line I operations. Initially the safety department was 

relatively small, with seven to eight individuals supporting Division B operations. Eventually 

this number grew to 10–15 individuals. This included safety inspectors, area safety engineers 

(responsible for a particular area), safety engineers (responsible for multiple areas), and safety 

management. Rarely, the safety personnel were sent to Division A to support operations or for 

training. Safety was also involved with criticality safety. The AEC conducted semi-annual 

audits of the safety program, including criticality safety and radiation protection. Inspectors 

were sent from the AEC office in Albuquerque. 

The safety department at the facility was privy to the types of weapons assembled, disassembled, 

and retrofitted. They had a general knowledge of the radionuclide constituents of the 

subassembly. 

Radiation Safety Training 

There was no formal radiation protection, criticality safety, and fissile material handling training 

onsite. The level of training depended on the position the employee held. Safety personnel 

received radiation protection training from the AEC, including training courses taught offsite 

(e.g., DESA Base, Nevada Test Site). Courses included training in radiation protection, 

explosive handling, industrial safety, and fissile material handling. Some individuals (e.g., 

safety, process engineering, and chemistry) were sent to LANL, Sandia, and Pantex for training. 

These classes covered fissile material handling, criticality safety, and emergency response. 

Personnel involved in radiography were provided training when they first started at the plant. 

There was facility safety training associated with work on Line I, but it was not extensive. 

Periodic radiation safety training sessions were conducted onsite. The contents of these meetings 

included all aspects of safety. During these meetings, they would discuss problems encountered 

in operations and the safety related to various operations. These meetings did not exclusively 

focus on radiation safety, but included dangers related to handling and processing explosives and 

the requirements for cleanliness in the work areas. Cleanliness was critical, as dust could be an 

explosive hazard. Some sessions included a discussion of the dangers of radiation and how to 

minimize exposure (e.g., time, distance, and shielding). Annual safety meetings were also held 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

75 of 92 

at the plant. Individuals received on-the-job training related to their particular job. Safety 

performed walkthroughs of the area, providing input on safe handling of radioactive material 

during these tours. 

Although the security force was frequently near the weapons and materials, they did not receive 

radiation safety training. The shift commanders of Physical Security Guards had the 

responsibility for providing first response for injuries. They were provided with no training 

related to this responsibility. The limited amount of information they were able to ascertain on 

safety was learned from documents left out by mistake. There was no formal safety training. 

Worker awareness of the presence of radioactive material in the facility seemed to vary. Some 

were cognizant they were handling this material, while others were blind to this fact. Safety and 

supervision tried to made individuals aware that they were handling radioactive material. The 

workers did gain a general awareness of what they were doing from the news media. 

Supervisors who were questioned told workers “Don’t worry, it’s clean enough to eat off of.” 

Workers were repeatedly reassured there was no radiation leakage from the pits. Some workers 

were aware of the potential hazards of select chemicals. Production workers could feel heat 

emanating from radioactive material. Hair on their arms would stand up and their legs felt 

prickly. Many workers were also aware that they were working with hazardous chemicals. 

As a group, workers were concerned about their safety and the safety of their coworkers. As 

workers become more aware of the hazards over time, they began to become more safety 

conscious. In general, site experts felt the radiation safety program at IAAP was lax. The 

corporate policy towards safety was to provide the worker with the best possible safe working 

conditions using the latest technology available at the time. This was a consistent policy over 

time. Although some workers believe the company would not put them in harm’s way, others 

indicated the hierarchy of priorities at the facility was production, security, and safety, in that 

order. 

The company maintained a record of safe workdays. Demonstrating good safety statistics was 

important to management. As a result, injured workers were strongly encouraged to return to 

work, even if they could only sit there for the remainder of the shift. 

When the AEC started to ship the pits and other material back to Pantex, the situation worsened. 

There were a couple of occurrences where pits and the beryllium shells were found lying on the 

floor. The AEC supervisors at the facility were not strictly enforcing safety requirements 

associated with the proper storage of weapons components. 

External Exposure 

The level of contact with radioactive components during weapons assembly was dependent on 

the phase of the process in which the individual was involved. Some jobs did not require 

handling the material at all, while others did. In some cases, this direct contact with pits was a 

routine part of a worker’s job. There was no contact with neutron generators, to the best of site 

experts’ knowledge. The highest exposure potential was associated with the assembly and 

disassembly process. The radiation exposure was reportedly worse in 1-11, 1-63, 1-61, and 1-13. 

Situations where radiological conditions were unknown, such as when the commander initially 

entered the transport vehicle, may have posed radiation exposure risks. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

76 of 92 

TracerLab and later Landauer provided external dosimetry services to the site. Whole-body dose 

was monitored via beta-gamma film badges to some extent throughout IAAP AEC operations. 

Thermoluminescent dosimeters (TLDs) were not used for the measurement of whole-body dose 

during AEC operations. The monitoring policy was to assign film badges to workers who 

performed hands-on work with radioactive material and to radiographers. X-ray technicians and 

radiographers were among those routinely monitored. Those individuals who had intermittent 

exposure, such as those walking through an area, were not assigned dosimeters (e.g., some 

production workers). Prior to 1962, film badge monitoring was intermittent, even for those who 

were assigned dosimeters. 

Workers were pulled from the area when they had exceeded their limits; the film badge data does 

not reflect this. Also, there are a number of individuals who entered areas where radiological 

hazards existed (e.g., the bays) who were not badged. In addition, the security force was 

responsible for shipping and receiving of materials as well as guarding stored materials. They 

were not routinely badged. The monitoring policy for workers was not standardized. For 

example, supervisors were badged rather than production workers. Dosimeter usage was not 

strictly enforced, so at times the workers did not wear their dosimeters while working with 

radioactive material. Although there was direct contact with radioactive material, not all workers 

assigned to a particular task were monitored with film badges. Many sites experts involved in 

production say they were not monitored with pocket ionization chambers or extremity badges. 

Dosimeters were provided to laboratory staff. The badges were worn during the operation of 

machines generating radiation or containing radioactive material. Workers did not wear their 

dosimeter when the units were not in operation. During staff shortages, the laboratory was 

provided with temporary support from other areas. These individuals were not provided 

dosimeters during their assignment to this area. 

Extremity dosimetry (i.e., ring and wrist dosimeters) was initially used intermittently due to the 

poor design of the dosimeters. When Landauer started producing extremity TLDs, there was an 

increase in use of extremity dosimeters. Extremity dosimetry was not assigned to many 

production workers, including those with direct access to pits. Pocket ionization chambers were 

used at times in the x-ray vaults. Safety staff did not find them very reliable. Timekeeping was 

not used at the facility to track worker dose. 

Few details on the design of the film dosimeter were obtained from site experts. They did 

remember that the dosimeters were green and rectangular in shape. Film badges were stored on 

racks at the AX-1 security post. There may have also been a storage rack in Building 1-100. 

Badges were exchanged periodically. Some film badges had individual names, while others did 

not. Control badges accompanied each shipment of dosimeters from Landauer. These were 

stored in the safety office. Site experts typically reported that when monitored, they wore their 

dosimeters on the collar of their coveralls. Other employees wore their dosimeter at their chest 

level. The radioactive source was typically at waist level or higher. Only a fraction of the 

individuals who worked in Division B were monitored. The used dosimeters were put into a box 

and new dosimeters were put in their place. Some type of inventory or processing apparently 

occurred at the laboratory on site. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

77 of 92 

Workers were not sure their dosimeters were actually being processed, so they marked a couple 

of the dosimeters and followed their movement to the lab. These dosimeters were later found in 

the trash. 

Personnel wore wedding rings and watches into the production areas. Jewelry, belt buckles or 

other metals were never confiscated by safety as a result of neutron activation. 

Workers were not cognizant of the biological risks associated with the exposure to radioactive 

material. No shielding, such as lead aprons, was used during production operations. Production 

workers came in direct contact with the pits. Workers could feel the heat generated from the 

hemisphere. Due to the orientation of the units, heat could be felt from the knees to the midtrunk. The smaller the unit, the hotter it was. Workers had to prevent body oil and dust from 

getting on the surface of the pits, so they used cotton gloves or Kimwipes to handle them. 

Internal Exposure 

Tritium reservoirs were received in small canisters. Alarming monitors detected airborne tritium 

releases during the decanting process. There may have been significant exposures related to 

work with tritium. Tritium leaks were a common occurrence at IAAP. Contamination surveys 

of the lifts and other areas indicated beta contamination from tritium. No flaking or loss material 

was observed on the pits. Other potentials for internal exposure were present at the burning 

fields and test areas. 

With respect to internal dose hazards, it should be noted that the average radon concentrations in 

the Iowa area are the highest in the nation, whereas radon concentrations in Texas are quite low. 

This invalidates the use of the Pantex indoor radon values in the TBD. A better method of radon 

exposure reconstruction would be the use of glass-based reconstruction detectors (Steck et al. 

2002). Workers often spent significant time in underground structures at IAAP. The potential 

for radon exposure is significant when one considers that that a yearly average radon 

concentration of 150 Bq/m3

 (4 pCi/L) imparts an estimated average annual dose of 200 mSv 

(20,000 mrem) to the target cells in the bronchial epithelium (Field 2005b). 

A limited bioassay program existed at the facility. Urine bioassay samples were collected from 

some workers several times per year, while others were not required to submit a single bioassay 

sample during the course of their employment on Line I. Some of the bioassay samples were 

analyzed onsite, while others were shipped offsite, according to site experts. In-vivo counting 

was not used to monitor internal exposure at the facility. Site experts were not familiar with the 

term “bioassay,” making it difficult to distinguish between medical and drug-testing urinalysis 

and that done for the purpose of radiation protection. 

Personnel protective equipment (PPE) included coveralls, safety shoes, safety glasses, gloves 

(occasionally), and face shields (occasionally). Site experts indicated that general job 

assignments were indicated by the color of coveralls worn. Management and Safety wore white 

coveralls. Those involved with HEs wore brown coveralls. Assembly workers wore green 

coveralls. Civilian clothing was worn under the coveralls. The plant provided conductor safety 

shoes, which were worn home. Cotton gloves were provided for some operations (e.g., handling 

pits). Work clothes and safety shoes would accumulate dust and chemicals over the course of 

the shift. Occasionally, they took their work clothes or parts of their work clothes home for 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

78 of 92 

laundering and families would come in contact with the material deposited on these clothes. 

Security personnel work uniforms. 

Shower facilities and change rooms were available at the plant. Some individuals took showers 

and changed, and some did not. Individuals from the HE, disassembly, and melts took more 

showers than others. Workers were not required to frisk when leaving the area. At times 

workers would run the Geiger counter over the body for fun. They did not detect radiation above 

background. Production’s work clothes were laundered on site. Security staff did not have 

access to showers or changing facilities and wore their uniforms home. 

Specific workers had additional or alternate personnel protective clothing. Painter’s masks were 

used in the HEs area. Personnel in the labs or involved with radiography were provided with 

lead aprons, face shields, gauntlets, safety glasses, and/or safety shoes, as needed. The 

production workers’ coveralls were laundered in the plant laundry. The guards’ were sent to 

Sickels Laundry in Burlington. The workforce did not use lead aprons when working around 

radioactive material. Contaminated laundry was reportedly shipped to Pantex for disposal. As a 

result of the shipment of laundry off site, there has been some concern with regard to 

contamination of public areas. 

Eating, drinking, smoking, or applying makeup in the immediate area of radioactive material was 

not allowed in general. For some security posts (e.g., buddy system posts) guards were not 

allowed to leave the area and therefore had to eat their meals at their duty station. Drinking 

water was available in the ramps, which were separated from the production area by a door. The 

ramps were enclosed covered walkways between bays and buildings. There were a few smoking 

areas in the ramps. 

There was ventilation within the production areas, due to the chemicals handled. Fume hoods 

were used for a few operations (i.e., venting tritium containers). One building housed a booth for 

sandblasting. Ventilation in the production areas varied based upon location. Buildings 1-61, 

1-63, 1-13, and 1-40 were sealed tight with a limited air exchange. There were many air leaks in 

walkways and some buildings. Other buildings, such as 1-63, 1-77, 1-73, 1-13, and 1-61, were 

climate controlled at 73.4 degrees and less than 15% humidity. When there was a failure in 

temperature and humidity controls, weapons had to be moved to other areas. Ramps were 

enclosed and heated. Buildings were air-conditioned. 

The assembly and disassembly processes occurred on tables in the middle of the room. 

Inspections also took place in an open area. In the case of an explosion, the Gerties (i.e., 

assembly and disassembly areas) were designed to seal themselves. Production workers did not 

use lead aprons. 

Field Radiological Control 

Special Work Permits or Radiation Work Permits were not used at IAAP. Safety Department 

Work Permits were issued when maintenance work was performed at the facility. Safety 

activities were directed by procedures, which were maintained by the Safety group. Emergency 

response (red bordered) procedures were placed at the entrance to each operating building. 

Specific safety instructions were written into operating procedures. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

79 of 92 

Radiation postings were at the entrance to areas involved in processing of radioactive material. 

These areas included 1-11, 1-12, 1-13, 1-61, 1-63, 1-73, 1-77, 1-100, the lab, and C Yard. Site 

experts remember seeing radiation labels on some units or containers. Postings and labels were 

the standard yellow and magenta postings with the trefoil. Following an OSHA visit in 1974, 

there was a marked increase in radiological posting at the plant. Hazardous material postings 

(i.e., chemical and cancer-causing) also increased during this period of time. 

The radiation survey instruments used at the IAAP included Victoreen 440 ionization chambers, 

Eberline PAC-3Gs, Geiger-Mueller counters (Geiger counters), scintillation detectors, T-289 

fixed tritium monitors, and T-290 portable tritium monitors. The Victoreen 440 was primarily 

used to perform surveys on x-ray units and radiography sources. It was also used for general 

area surveys. Both the T-289 and the T-290 were flow-through ionization chambers used to 

monitor for airborne tritium. 

The first individual entering the assembly/disassembly area each morning was required to 

response-check an area Geiger counter. If it didn’t respond correctly, no one was allowed in the 

building until a functional meter was obtained. When a replacement Geiger counter had to be 

obtained, Security was required to escort the individual and the replacement meter into the area. 

Direct contamination was measured with a Geiger counter. These surveys were conducted on a 

monthly basis. Swipes were taken to evaluate removable contamination in the production areas 

and on material shipped and received at the site. A fraction of the pits opened per day for 

weighing and inspection were swiped. The swipes were analyzed for contamination on a 

scintillation detector. Little or no wet chemistry was done on the swipes. 

Dose rate measurements were taken in some areas along Line I. There were radiation readings 

observed periodically in the Igloos and other operating areas; however, they were not high 

enough to cause any safety concern. The configuration and number of items allowed in a 

particular area limited the external exposure in those areas. 

Regular neutron surveys were not conducted at the facility. IAAP did have a neutron monitor 

onsite in case of an incident. At one time visitors from Battelle in Washington State performed 

an analysis of neutron exposures on a unit at the facility. 

Air sampling and external radiation measurements were performed in the control room during 

the hydroshots. The air filters were tested for alpha contamination. Hydroshots dispersed large 

and small pieces of uranium oxide. The larger pieces were driven into the ground. Smaller 

pieces may have been found on the surface. As previously mentioned, larger pieces were 

retrieved. This work required heavy leather gloves to protect the hands. There was an 

established waiting period prior to re-entry into the site. 

There was an extensive area dosimetry monitoring program for gamma exposure. Area 

dosimeters were placed in production areas and storage areas. Area dosimeters were hung on the 

walls in storage and production areas. They were similar to the personnel dosimeters. Film 

badges were placed at or above the individual’s head. In general, workers were closer to the 

source term than was the area dosimeter. For example, the worker may be in contact with the 

radioactive material, but the area film badge was located several feet away. Although little 

information is available on the storage of pits and other radioactive weapons components, area 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

80 of 92 

monitors were placed in these areas. There were storage yards with annual radiation exposures 

exceeding 8 rem per year. The levels are reflected in a letter to the Board from Dr. William 

Field (Field 2005a). 

T-289 monitors were wall-mounted radiation monitors with alarm capabilities and lights (i.e., 

green, red and yellow). These were used in the tritium storage buildings and some production 

areas, such as Buildings 1-11, 1-13, 1-61, and 1-63. T-290 tritium monitors were portable and 

resembled a suitcase. The monitors were often put on onsite transport vehicles, or were put in 

areas where tritium monitoring was needed. Both tritium monitors were very sensitive. When 

the tritium shipping container was opened, the T-289 would occasionally measure some airborne 

tritium. 

Limited information is available on waste management practices at IAAP. There were special 

containers for the disposal of swipes and Kimwipes. These were periodically removed from the 

area. Radioactive waste was generated as a part of the disassembly process. Radioactive waste 

shipments were sent to Pantex in the 1970s. Contaminated clothing was included in these 

shipments. Records also indicate that Cs-137 was sent to Pantex from Burlington. The source of 

the Cs-137 is unknown. When Line I was cleaned, the area was hosed down, mopped, and the 

water swept out the door. The contents of this waste were not always known. 

Environmental Monitoring 

For a period of time, there was some perimeter monitoring for radiation. Each cell had an 

individual filter system that ventilated to the outside. The tritium can was vented in an openfaced fume hood. Some of the tritium was released through the stack. There was environmental 

monitoring related to explosive contamination, solvents, adhesives, and other chemicals. Site 

experts were not certain whether stack monitoring data was available. 

Tests related to the nuclear weapons program were performed at the firing site several times per 

week. Newspapers reported the release of radioactivity to the environment from these blasts. 

Smoke blew all over, including offsite. When the air currents were right, contamination from the 

burning fields and firing sites was spread to Middletown, Burlington, or West Burlington. The 

kids of Middletown reportedly liked to play in what they referred to as “the clouds.” 

Impound pools were maintained on the backline. Material from operations was allowed to flow 

in these pools. The water would turn a reddish color, due to the material released into the pool. 

A pipeline ran between Line I, and Lines 2 and 3, to the plant spillway. Long Creek ran into the 

plant lake and over the spillway to the Skunk River. Mathis Lake was the only source of 

drinking water to the plant for years before connecting to the Burlington city water supply. This 

was also the source of water for residents adjacent to, or on, the plant property. Long Creek 

passed through the firing site on its way to the Skunk River, then to the Mississippi River. RDX 

contamination was identified in groundwater around nearby Wever, Iowa. Biological organisms 

have been used to assist in the cleanup of the contamination in the area (presumably, chemical 

contamination). Site experts noted that there were occasions when wildlife in the creek died due 

to contamination from the site. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

81 of 92 

After the end of the AEC mission, the facility was cleaned and checked. The site was eventually 

named a Superfund site. When the site was remediated, the burning field was excavated. The 

plant maintained an onsite disposal site. Plant waste was disposed of in this area. Bags of 

beryllium and other metals were retrieved from this area. Material was relocated to berms on the 

west side of the property. 

Line I Incidents and Unusual Occurrences 

In the case of an incident or unusual occurrence, workers were directed to contact Safety and/or 

Security. Emergency response procedures were available at the entrance to a particular facility. 

Personnel were trained on how to respond to tritium monitor alarms or unexpected incidents 

involving safety. 

There were numerous injuries at the plant, including abrasions, cuts, smashed fingers, 

overexposure to chemicals, etc. These were primarily associated with the production activities. 

There were a lot of burns observed in the Melt area. When an individual had more significant 

injuries, they were taken to the site hospital (basically a first-aid station) for treatment. 

Following this they were returned to work to finish the shift. If injuries were minor, personnel 

would take care of the situation on their own (e.g., wrap the area with masking tape) to avoid 

going to the site hospital. Safety reports were filed; however, it is uncertain whether these 

reports were retained. 

According to safety personnel, radiation incidents were few and far between. There was at least 

one occurrence where a woman was reassigned to another job due to excessive radiation 

exposure. There were a number of industrial safety incidents. No skin or personnel 

contamination incidents were recorded at IAAP from 1958–1974. Prior to this, it is unknown, as 

the safety staff members interviewed started employment in 1958. 

Tritium monitors (T-289 monitors) were mounted on the walls in various areas. The unit had an 

alarm function with red, yellow and green lights. When the T-289 alarm sounded, occupants 

were directed hold to their breath and to exit the area immediately. Evacuation of some areas 

was time-consuming, since only one person at a time could exit through the revolving doors. 

Security personnel fell back to a secondary position. Sometimes they used their vehicles to 

surround the building after an alarm. The Safety Department was notified of the alarms and 

entered the area with a meter to determine the radiological conditions. At times the building was 

declared off limits for the remainder of the shift and at other times personnel were allowed back 

after Safety had declared it safe. Personnel were not provided with an explanation of why the 

unit alarmed. The frequency of alarms became more prevalent starting in the late 1960s. The 

alarms on these monitors would frequently go off and become a nuisance. As a result, these 

monitors were turned off or the alarm set point was raised. In other cases, the T-289 monitors 

were found unplugged. Security maintained a log of radiation monitoring alarm occurrences and 

noted that there appeared to be fewer alarms immediately following calibration of the equipment. 

Many of the incidents involved accidents with HEs that were processed on mills, lathes, or other 

machines. In one instance, an individual was working on a hydraulic press. Hydraulic presses 

were used to press explosives into a container. Explosives were compressed on a press at 20,000 

psi. When the individual went to use the press, the machine plug shot up through the roof and 
 

 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

82 of 92 

back down to the ground. The press was destroyed as a result of this. No personnel were 

injured. There were two additional incidents involving presses. 

Some workers reported seeing a blue flash in a cell once, which could have been any number of 

things. Some workers maintain that this was a criticality. Another possible explanation is that 

the tester was hooked up to the wrong charge, and there was a blue flash. There was no 

explosion associated with the incident. 

There is a story of a couple of men who were burned in some sort of accident in Building 1-63. 

They were removed from the facility via ambulance. Eventually they were transferred to Iowa 

City, Iowa, due to massive burns. Both men died within a few days. Not much detail is known 

relating to this incident and paper evidence is absent. The incident was kept hushed. The 

workers may have been visitors from another facility. A shift lieutenant and security guard went 

into a Gravel Gertie and brought them out. The security personnel both suffered health 

problems. 

Two production workers, highly skilled in disassembly of weapons, were approached by their 

supervisor to assist in the disassembly of a particular weapon (i.e., Mark 25) that had been 

shipped to IAAP. After much coaxing and a promise that they could leave early, these men 

agreed to do the disassembly. This weapon had fallen out of the bomber door and skidded down 

the runway. It was evident that the weapon had been exposed to flames, as there was some 

blackness on the weapon. The sphere was very difficult to pull apart, so they had to use the press 

to assist in this task. Facility management and workers were very concerned about a 

compression incident, so care had to be taken. Site experts indicated that the pit was intact. 

Following the completion of this task, the men were not allowed to go home early. As a result, 

they did not agree to perform anymore of these types of disassemblies. They were asked one 

other time to perform a special disassembly and declined. The details are not known with 

regarding this request. 

Site experts do not recollect explosions (other than hydroshots) that could have dispersed 

radioactive material. There were no fires associated with the pits; however, the adhesive would 

get hot and flame if left sitting too long. 

As with many facilities, workers were involved in unauthorized practices. To initiate new 

guards, senior guards would use a steel brush on the pits to show them the resulting sparking 

without the knowledge or consent of supervisors. Several site experts have reported occurrences 

where pits were dropped. One shift commander reported visiting a disassembly site that had the 

explosive ball frozen and cracked open. The pit was lying on the cement floor with a vacuum 

pump attached. A couple of the workers wanted to be cute and dropped a 20–30-lb chunk of 

explosive on the floor to see if security would get excited. 

Chemical Usage 

Site experts reviewed a chemical inventory associated with weapons production and indicated 

that the following chemicals were used at IAAP in the weapon production process. Some of 

these chemicals were used in the HE manufacturing process. This is not a comprehensive list of 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

83 of 92 

all chemical used throughout the AEC operation, but lists some of the more frequently used 

items. 

Acetone 

Acetylene 

Alcohol (methanol, isopropyl, ethyl) 

Barium
 

Boron 

Dichlorodifluoromethane 

Dry Ice 

Glacial Acetic Acid 

High Melting Explosive (HMX) 

Hydrochloric Acid 

Kerosene 

Methyl Ethyl Ketone (MEK) 

MOCA (adhesive) 

Oxygen 

Plastic Bonded Explosive (PBX) 

Pentaerythritol Tetranitrate (PETN) 

Polyester Resin 

Cyclotrimethylenetrinitramine (RDX) 

Sulfuric Acid 

Tetryl 

Thinner (enamel, paste stencil) 

Trinitrotoluene (TNT) 

Toluene 

Trichloroethylene 

This information is provided so that any interactions between the chemicals and the nuclear 

components of the weapons can be evaluated. 

Beryllium exposure was of significant concern. Beryllium tools were used in operations because 

they would not spark. These tools had to be sharpened occasionally by the machine shop. There 

was also beryllium exposure in the machine shops. At times the fork lift drivers would run into 

walls, causing release of asbestos. 

Medical Exams 

Individuals received medical exams upon initial hire, periodically thereafter, and at termination. 

Physical exams occurred as often as once or twice per year. Individuals also had to be evaluated 

by Medical if they were on sick leave for extended periods of time. Medical exams included 

urinalysis, blood work, a hearing test, a vision test, and a standard chest x-ray. X-rays were 

taken in the posterioanterior position with the shoulders against the plate. Security also received 

a back exam. At one period of time, the plant doctor refused to perform x-rays until a new unit 

was available, because the existing x-ray machine was too dangerous for use. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

84 of 92 

Safety Records 

Radiation protection support was provided by onsite personnel. The Safety Department 

maintained a file on each monitored worker. Dosimeter readings were maintained in batches. 

Some records were copied and place in a worker’s medical file. The type of report issued by 

Landauer was based on the regulations that applied at the time. With respect to IAAP dosimetry 

results, the DOE reporting regulations should be consulted. There are times in history when a 

vendor was not required to report both deep and shallow dose. 

Personnel radiation exposure records included results of badge reports and cumulative exposure. 

Badging frequency could also be determined from information in the record. Many workers 

have never seen the contents of their radiation exposure file. During the period of operation, 

formal radiation exposure reports were not issued to monitored employees. Some monitored 

workers were told whether they were within limits or not. 

Landauer presently maintains a comprehensive collection of historical records, including all the 

film submitted for processing since the inception of the company. There is information available 

on dosimeter design and calibration procedures. This information was previously provided to 

NIOSH; however, it is uncertain whether the Office of Compensation Analysis and Support or 

another group received this information. 

When AEC discontinued operations at IAAP, they sent the records to Pantex. One former 

employee of Pantex was involved in a review of IAAP records at the Pantex Plant. This was the 

result of repeated requests for radiation monitoring data and incident reports. There are a few 

hundred boxes of records that were presumably shipped to Pantex when IAAP AEC operations 

discontinued. As these records have never undergone a formal review for classification, all 

records are stored in a Q-cleared facility. Records include air monitoring, survey, and personnel 

monitoring records. Also included are beryllium air monitoring records, incident and accident 

reports, and administrative procedures. Additional records may be available at LANL; however, 

this has not been verified. There are no publicly available historical records. IAAP Safety 

personnel interviewed indicated that field survey data and personnel monitoring data were not 

marked as classified data. 

Records retrieved by the University of Iowa as a part of the medical surveillance study took a 

considerable effort to obtain, due to security issues and identification of the location of records. 

A limited number of records have been identified at the Pantex Plant. There may be additional 

records in Albuquerque, since this field office oversaw operations at IAAP. When the University 

made the original inquiry for the records at Pantex, they requested all records relating to 

operations at Burlington. Pantex provided an inventory of records they had in the “vault,” which 

comprised the contents of six boxes. The inventory list was reviewed by Pantex to insure 

information provided was not classified. Whether the inventory was sanitized is uncertain. 

There is limited data available on individual work histories. The dataset compiled by the 

University of Iowa includes personnel identifiers, date of termination, job codes, area dosimeter 

readings, and individual dosimeter readings, where available. The only specific work history is 

that obtained from the workers themselves. This makes determination of dose by category 

difficult, if not impossible. Other then self-reported information, there is no way of knowing 

which buildings an individual may have been assigned to. 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

85 of 92 

Linkage between individual film badge readings and work location are possible based on 

personal knowledge; however, the available records do not contain specific information to allow 

for this type of linkage. Workers periodically changed job assignments, and thus work locations, 

making this more difficult. 

Both field and personnel monitoring at IAAP are incomplete, based on the information reviewed 

to date and discussions with former IAAP workers. During the course of the work performed by 

University of Iowa, the researchers have not been able to locate standard operating procedures 

for health and safety, and criticality safety. Nor were they able to locate any bioassay data, 

including tritium bioassay data, which, they were told, started at the plant in the 1950s. No 

calibration procedures for radiation monitoring equipment have been found. Limited amounts of 

area monitoring data are available. 

Site Profile Comments 

NIOSH conducted a worker outreach meeting at the union hall in Burlington on July 29, 2004. 

NIOSH staff formally documented this meeting, and copies have been recently distributed to the 

workers involved in the meeting for their comments. This meeting was held to specifically 

discuss Revision 0 of the IAAP site profile (ORAU 2004). Site experts indicated that Revision 0 

of the IAAP site profile did not reflect the operations occurring at the plant. Some worker input 

has been integrated into the site profile, while other input has not. There is a general concern 

regarding the transparency of the dose reconstruction process and the generalities associated with 

the document. 

References 

Field, R.W., 2005a. Letter dated April 22, 2005, to Paul Zeimer and other members of the 

Advisory Board on Radiation and Worker Health. 

Field, R.W., 2005b. “Three Mile Island epidemiologic radiation dose assessment revisited: 25 

years after the accident,” Radiation Protection Dosimetry, 113(2):214–217. 

ORAU, 2004. “Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP),” ORAUT-TKBS-0018, Rev. 00, Oak Ridge, Tennessee. 

ORAU, 2005. “Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP),” ORAUT-TKBS-0018, Rev. 01, Oak Ridge, Tennessee. 

Steck, D.J., M.C. Alavanja, R.W. Field, M.A. Parkhurst, D.J. Bates, and J.A. Mahaffey, 2002. 

“

210Po implanted in glass surfaces by long term exposure to indoor radon,” Health Physics, 

83(2):261–271. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

86 of 92 

ATTACHMENT 5: CLASSIFIED REVIEW AGENDA 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

87 of 92 

ATTACHMENT 6: ASSESSMENT OF DOSE RATES FROM “GENERIC
 

PIT” 

Appendix D of the TBD presents a summary of the assessment of the external dose rate from a 

“generic pit,” which is represented as a bounding exposure for the purpose of evaluating worker 

doses during the 1949–1962 period at IAAP. SC&A has performed its own analysis of this 

scenario, using the parameters presented in Appendix D. The SC&A analysis utilized the Los 

Alamos Monte Carlo code MCNP5 (LANL 2003), a revision of the MCNP4C code used by 

NIOSH. 

Various isotopic mixtures of plutonium can be used in nuclear weapons. In order to study the 

effect of such different compositions, we performed a set of five analyses. Each analysis, in turn, 

assessed the dose rate from one of the five principal radionuclides found in plutonium weapons: 

Pu-238, Pu-239, Pu-240, Pu-241, and Am-241. 

In addition to plutonium isotopes and highly enriched uranium, U-233 was produced at DOE 

nuclear defense production plants (DOE 2003). According to Fretwell (2002), a composite 

U-233/plutonium weapon was reportedly detonated at the Nevada Test Site in 1955. Uranium233 was processed at the Rocky Flats Plant between 1965 and 1982 (Freiboth and Gibbs 2000). 

During early production, the material was contaminated with about 50 ppm of U-233. In later 

years (1974–1977), the U-232 contamination was reduced to 7–8 ppm. In order to evaluate the 

dose rate from such a weapon, we performed an MCNP analysis of a U-233 pit. 

Exposure Geometry 

Because of the intimate geometrical relationship between the receptor and the source, the 

receptor geometry was described by a MIRD phantom. The phantom used in the simulations is a 

custom version of BodyBuilder, a commercial MIRD phantom computer program from White 

Rock Science.1

 This program generates an MCNP geometry description for a MIRD-type 

anthropomorphic phantom of a specified age, from infant through adult. The phantom's sex may 

be chosen, as well as which organs to include in the model. The models produced by 

BodyBuilder are based on the descriptions for several ages (newborn, ages 1, 5, 10, and 15 years, 

adult female, and adult male) by Cristy and Eckerman (1987). A 21-year-old androgynous 

phantom, with female breasts and both male and female gonads, was used in the present analysis 

(see Figure 1). 

The calculated organ doses were summed to determine effective dose, using the ICRP-60 

methodology. Two assumptions were made: 

(1) Red bone marrow is distributed over entire skeleton 

(2) Red bone marrow and bone surface dose are equal

 1 P.O. Box 4729, Los Alamos, NM 87544 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

88 of 92 

The plutonium pit was assumed to be a spherical shell, with an 

outer radius of 15.24 cm, an inner radius of 15.11 cm, and a density 

of 16 g/cm3

, which yield a total mass of 6,019 g of plutonium 

metal. The U-233 pit was also modeled as a hollow sphere. 

Because U-233 has a higher critical mass than Pu-239, the sphere 

was assumed to have a mass of 16 kg. The density of uranium is 

19.1 g/cm3

; the sphere has an outer radius of 15.24 cm and an inner 

radius of 14.947 cm, which yield a total mass of 16,022 g of 

uranium metal. 

The source and the receptor were surrounded by moist air above a 

30-cm-thick slab of concrete. 

Two exposure geometries were evaluated: 

(1) A standing phantom, facing the shell at a distance of 100 cm from the center of the shell 

to the center of phantom (see Figures 1 and 2). The center of the pit is 100 cm above the 

floor. 

Figure 1. Standing 

Phantom
 Figure 2. Standing Phantom with Pit 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

89 of 92 

(2) A seated phantom, with the spherical shell in its lap (see Figure 3). 

The analysis of the plutonium pit was confined to the principal 

x-ray and γ-ray emissions from each of the five radionuclides. 

These photon spectra were based on data compiled by the Tokai 

Research Establishment, JAERI (2001). Electrons, β rays, 

bremsstrahlung x-rays, and the photon and neutron spectra from 

spontaneous fission were not included. These radiations were 

judged to constitute a small fraction of the total dose. 

Before assessing the dose rates from the U-233 pit, we performed 

scoping analyses to estimate the relative contributions of U-232, 

which is present as a contaminant. Uranium-232 decays to 

Th-228, which has a 1.9-year half-life. Thus, 15-year-old U-232 

would essentially be in secular equilibrium with Th-228 and its 

short-lived progeny, which include highly energetic γ emitters, 

notably Tl-208. We confined our analyses to the principal x-ray 

and γ-ray emissions from Th-228 and its progeny (U-232 itself 

produces no significant photon radiation). 

Results 

The results of the calculations on the plutonium pit are shown in 

Table 1. The values in the columns headed “Normalized Dose 

Rate” are derived from the MCNP calculations for the two 

exposure geometries described above. These values are 

normalized to a mass fraction of one for each isotope—i.e., the specific activity of the given 

isotope is the same as if the pit were composed entirely of that one isotope. 

Figure 3. Seated Phantom 

with Pit 
 

 

 

 

Effective Date: Revision No. Document No. Page No. 

June 29, 2005 0 (Draft) SCA-TR-TASK1-0009c 90 of 92 

Table 1. Dose Rates from Generic Plutonium Pit 

Nuclide 

Normalized Hanford Weapons Grade Hanford Reactor Grade 

 Dose Rate (mrem/h) Fraction 

(g/g) 

Dose Rate (mrem/h) Fraction 

(g/g) 

Dose Rate (mrem/h) 

Standing Seated Standing Seated Standing Seated

Pu-238 676.57 1,763.33 4.44E-04 0.30 0.78 8.87E-03 6.0 15.6 

Pu-239 8.00 23.93 9.30E-01 7.45 22.29 5.50E-01 4.4 13.2 

Pu-240 8.43 21.87 5.98E-02 0.51 1.31 2.60E-01 2.2 5.7 

Pu-241 121.32 375.88 3.86E-03 0.47 1.45 6.28E-02 7.6 23.6 

Am-241 9,563.52 26,807.16 4.06E-03 38.85 108.91 6.59E-02 600.9 1,684.4 

Total — — 9.98E-01 47.59 134.75 9.47E-01 621.1 1,742.5 

There is considerable uncertainty regarding the actual composition of the plutonium pits handled 

at IAAP. Since no composition data are presented in the IAAP TBD, we used the activity 

composition of Hanford reference weapons-grade plutonium (ORAU 2004, Table A2.3) to 

derive the mass fraction of each of the principal nuclides after 15 years of decay and ingrowth. 

These mass fractions and the corresponding dose rates are listed in Table 1. Furthermore, a test 

of a nuclear weapon using reactor-grade plutonium was conducted in 1962 (DOE n/d). We 

therefore calculated the dose rates from a pit composed of reactor-grade plutonium. The mass 

fractions were derived from the activity composition of Hanford reference fuel-grade plutonium 

(ORAU 2004, Table A2.4). The results are shown in Table 1. 

Table 2 shows the dose rates from a 15-year-old, 16-kg uranium sphere containing varying 

concentrations of U-232. Except for the more massive, thicker, and denser sphere consisting of 

uranium metal, the exposure geometries are the same as for the plutonium sphere. 

Table 2. Dose Rates from U-232 Contamination in Uranium Pit 

Concentration Dose Rate (mrem/h) 

(ppm) Standing Seated 

1 3.43E+02 1.11E+03 

7.5 2.57E+03 8.30E+03 

50 1.72E+04 5.54E+04 

Discussion and Conclusions 

The dose rate of 48 mrem/h from the generic pit of weapons-grade plutonium at a distance of 

1 m is consistent with the dose rate of 33 mrem/h calculated by NIOSH, given the variability in 

the isotopic composition. However, the dose rate from the pit in the lap of the seated phantom, 

135 mrem/h, is significantly higher. This scenario was included in our analysis on the basis of 

information furnished by workers, who said that workers carrying the pits held them against their 

bodies. Holding the pit in the lap, while at the high end of plausible scenarios, is a scenario that 

should be addressed in the TBD. 

The dose rates from reactor-grade plutonium are more than 1 order of magnitude greater than 

those from the weapons-grade material. Pu-239 constitutes only 55% of reactor-grade 

plutonium, compared to about 93% of weapons-grade material. The reactor-grade metal thus has 
 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

91 of 92 

higher fractions of other plutonium isotopes, notably Pu-241, which decays to Am-241, the 

principal contributor to the dose. 

Given the lack of publicly available information to the contrary, we cannot rule out the 

possibility that weapons contaminated with U-232 might have been processed at IAAP. Were 

this the case, the dose rates could be up to 3 orders of magnitude greater than those from the 

generic plutonium pit. This issue needs to be addressed in the TBD. 

References 

Cristy, M. and K.F. Eckerman, 1987. “Specific Absorbed Fractions of Energy at Various Ages 

from Internal Photon Sources. I. Methods,” ORNL/TM-8381/V1, Oak Ridge National 

Laboratory, Oak Ridge, Tennessee. 

Department of Energy (U.S.) (DOE), undated. “DOE Facts: Additional Information Concerning 

Underground Nuclear Weapon Test of Reactor-Grade Plutonium,” Office of the Press Secretary. 

<http://www.osti.gov/html/osti/opennet/document/press/pc29.html> (April 14, 2005) 

DOE, “Integrated Safety and Project Management,” 2003. <http://www.ne.doe.gov/ISPM/ispmnew.html > (April 14, 2005) 

Freiboth, C. J. and F.E. Gibbs, 2000. “Disposition of Uranium-233 (233U) in Plutonium Metal 

and Oxide at the Rocky Flats Environmental Technology Site,” IT Corporation, Los Alamos, 

New Mexico. <http://www.osti.gov/bridge/product.biblio.jsp?osti_id=774607> (April 14, 2005) 

Fretwell, L., 2002. “Atmospheric Testing, Part Three.” 

<http://nuclearhistory.tripod.com/testing3.html > (April 14, 2005) 

International Commission on Radiological Protection (ICRP), 1991. “1990 Recommendations of 

the International Commission on Radiological Protection,” Annals of the ICRP, Publication 60, 

Pergamon Press, Oxford, England. 

Los Alamos National Laboratory (LANL), 2003. “MCNP5: Monte Carlo N-Particle Transport 

Code System, RSICC Computer Code Collection,” computer software and manual, Oak Ridge 

National Laboratory, Oak Ridge, Tennessee. 

Oak Ridge Associated Universities (ORAU), 2004. “Technical Basis Document for the Hanford 

Site—Site Description,” ORAUT-TKBS-0006-2, Rev.0, Oak Ridge, Tennessee. 

<http://www.cdc.gov/niosh/ocas/pdfs/tbd/hanfd2a.pdf> (April 15, 2005) 

ORAU, 2005. “Technical Basis Document for Atomic Energy Operations at the Iowa Army 

Ammunition Plant (IAAP),” ORAUT-TKBS-0018, Rev. 01, Oak Ridge, Tennessee. 

Tokai Research Establishment (JAERI), 2001. “DECDC 1.0: Nuclear Decay Data Files for 

Radiation Dosimetry Calculations,” DLC-213, RSICC Data Library Collection, computer 

software and manual, Oak Ridge National Laboratory, Oak Ridge, Tennessee. 
 

 

Effective Date: 

June 29, 2005 

Revision No. 

0 (Draft) 

Document No. 

SCA-TR-TASK1-0009c 

Page No. 

92 of 92 

ATTACHMENT 7: JACK FIX: MEMORANDUM TO FILE 

Memorandum to file from Jack Fix, Battelle Northwest Division, “Personal Communication on 

April 6, 2005 with Bill Endress,” April 6, 2005.