United States Government Accountability Office

GAO Report to Congressional Addressees

NUCLEAR SAFETY

DOE’s Investigation of 

Phosgene Gas 

Contamination Was 

Inadequate, but 

Experts Conclude 

That Worker Safety 

and Facilities Are Not 

Threatened 

May 2007 

 

GAO-07-712 
What GAO Found

United States Government Accountability Office

Why GAO Did This Study

Highlights

Accountability Integrity Reliability

May 2007

NUCLEAR SAFETY

DOE’s Investigation of Phosgene Gas 

Contamination Was Inadequate, but 

Experts Conclude That Worker Safety and 

Facilities Are Not Threatened 

Highlights of GAO-07-712, a report to 

congressional addressees

More than 700,000 tons of uranium 

are stored at two Department of 

Energy (DOE) sites where uranium 

enrichment took place and where

two facilities are being constructed 

to treat depleted uranium. Some of

the storage cylinders for uranium

came from the Army more than 50 

years ago and may originally have

contained phosgene, a toxic gas

used as a chemical weapon in 

World War I. In September 2005,

DOE’s Inspector General issued an 

alert warning that residual

phosgene, if present, could

threaten the safety of people and

the treatment facilities. 

GAO was directed to review DOE’s 

investigation of possible phosgene

contamination of uranium storage 

cylinders. GAO consulted a panel 

of experts to assess the adequacy

of DOE’s investigation and whether 

possible phosgene contamination 

could threaten the new treatment

facilities under construction. 

What GAO Recommends

GAO recommends that the 

Secretary of Energy strengthen 

DOE’s review process for safety

investigations to include reviewers 

who are independent of the 

investigations being done and can 

provide objective evaluations of the 

methods used and the findings and 

conclusions reached.

DOE agreed that workers and the 

public were not at risk but did not 

believe that its investigation had 

flaws. DOE did not comment on 

our recommendations. 

According to members of GAO’s expert panel, although DOE adequately 

demonstrated that the public would not be harmed if small amounts of 

phosgene escaped from the storage cylinders, it neglected to explicitly 

document its analysis of worker safety in its investigation of possible 

phosgene contamination. DOE’s regulations and guidance call for thorough 

safety analyses of newly identified hazards, such as possible phosgene 

contamination, to protect workers and the public. Yet DOE assumed, 

without explicitly documenting, that existing worker safety procedures were 

adequate to protect workers from the possible presence of phosgene. After 

GAO identified the need for DOE to support this key assumption, DOE 

provided supplemental information on worker safety; GAO’s panel agreed 

that this supplement sufficiently supported DOE’s position. In addition, 

although DOE’s guidance calls for independent review of investigation 

results, DOE officials supervising the phosgene investigation also served as

reviewers. This lack of independent review may have contributed to 

weaknesses in the investigation. 

The experts GAO consulted agreed that, for two reasons, the facilities under 

construction in Ohio and Kentucky would not be threatened by possible 

phosgene contamination of uranium storage cylinders. First, at the start of 

treatment operations, cylinders containing depleted uranium will be placed 

inside pressure vessels designed to withstand and contain any leak from a 

cylinder. If phosgene were present, it would not affect either the pressure 

vessels or the treatment facilities. Second, during subsequent steps, any 

phosgene that may be processed with the depleted uranium would be 

destroyed by the extreme heat and water vapor applied during the treatment 

process. 

Uranium Storage Cylinders at Paducah, Kentucky 

Source: Uranium Disposition Services.

www.gao.gov/cgi-bin/getrpt?GAO-07-712.

To view the full product, including the scope 

and methodology, click on the link above. 

For more information, contact Gene Aloise at 

(202) 512-3841 or AloiseE@gao.gov. 
Contents 

Letter 1

Scope and Methodology 3

Results in Brief 5 

Background 8

DOE’s Investigation of Possible Phosgene Contamination Did Not 

Adequately Document Analysis of Worker Safety 11 

Possible Phosgene Contamination of Uranium Storage Cylinders 

Does Not Threaten Depleted Uranium Conversion Facilities 17 

Conclusions 18

Recommendations for Executive Action 19 

Agency Comments and Our Evaluation 19 

Appendix I Comments from the Department of Energy 23 

Appendix II GAO Contact and Staff Acknowledgments 36 

Table 

Table 1: GAO’s Expert Panelists, Titles, and Affiliations 5 

Figures 

Figure 1: Uranium Storage Cylinders at DOE’s Paducah Site 9 

Figure 2: Cylinder with an Open Hole 16 

Figure 3: Steps to Convert Depleted Uranium Hexafluoride to 

Uranium Oxide, with Impact on Phosgene, If Present 18 

Page i GAO-07-712 Phosgene Contamination
Abbreviations 

DOE Department of Energy 

UDS Uranium Disposition Services 

USEC U.S. Enrichment Corporation 

This is a work of the U.S. government and is not subject to copyright protection in the 

United States. It may be reproduced and distributed in its entirety without further 

permission from GAO. However, because this work may contain copyrighted images or 

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reproduce this material separately. 

Page ii GAO-07-712 Phosgene Contamination
United States Government Accountability Office

Washington, DC 20548 

May 31, 2007

The Honorable Byron L. Dorgan 

Chairman 

The Honorable Pete V. Domenici 

Ranking Minority Member 

Subcommittee on Energy and Water 

Committee on Appropriations 

United States Senate 

The Honorable Peter J. Visclosky 

Chairman 

The Honorable David L. Hobson 

Ranking Minority Member 

Subcommittee on Energy and Water Development 

Committee on Appropriations 

House of Representatives 

The Honorable Mitch McConnell 

United States Senate 

From the 1940s, one of the missions of the Department of Energy (DOE) 

and its predecessors was to enrich uranium as a source of nuclear material 

for defense and commercial purposes. Before it can be enriched, uranium 

is combined with fluorine to form uranium hexafluoride, a substance 

dangerous to human health and the environment because it is radioactive 

and forms potentially lethal compounds if it comes in contact with water. 

The enrichment process results in two principal products: (1) enriched 

uranium hexafluoride, which can be further processed for specific uses, 

such as nuclear fuel or weapons, and (2) depleted uranium hexafluoride, a 

material that can be converted into a more stable form for storage and

other applications. Both processes—uranium enrichment and depleted

uranium conversion—involve hazardous materials and processes that can 

harm the public, workers, and the environment. DOE therefore requires 

specific safety procedures to be in place at uranium-processing sites. 

Uranium-processing activities took place at three sites near Paducah,

Page 1 GAO-07-712 Phosgene Contamination
Kentucky; Portsmouth, Ohio; and Oak Ridge, Tennessee,1

 where over 

700,000 tons of uranium hexafluoride is currently stored. At the Paducah 

and Portsmouth sites, DOE is constructing two new facilities to convert 

depleted uranium hexafluoride into a more stable compound, uranium 

oxide, for long-term storage. 

Between 1945 and the mid-1950s, the Atomic Energy Commission, a DOE 

predecessor, acquired from the U.S. Army Chemical Warfare Service more 

than 2,500 of the approximately 63,000 steel cylinders in which it now 

stores uranium hexafluoride. The Army previously stored other chemicals

in these 2,500 cylinders, including a toxic gas called phosgene, which was 

used as a chemical weapon during World Wars I and II. Phosgene can 

immediately endanger health or life, even in quantities as small as 2 parts 

per million. If inhaled, the gas damages the lungs, causing them to fill with

fluid and potentially leading to death by suffocation or heart failure. DOE’s 

records from 1946 indicate that some of the storage cylinders it received

from the Army tested positive for phosgene; the records do not indicate,

however, which cylinders tested positive, how much phosgene was 

present, or whether DOE removed the phosgene before using the cylinders 

to store uranium hexafluoride. 

In September 2005, DOE’s Inspector General issued an urgent letter, called 

a management alert, to DOE regarding the possible presence of phosgene 

in the cylinders received from the Army. The alert warned that the 

possible presence of phosgene in uranium storage cylinders had 

significant implications for the safety and health of workers and the 

public. In response to the Inspector General’s alert, DOE identified 2,5092

cylinders suspected of containing phosgene, immediately suspended 

regular maintenance activities around these cylinders, implemented 

precautions to protect workers from the potential phosgene hazard, and 

began an investigation of phosgene contamination of the 2,509 cylinders. 

 1

DOE processed uranium at the site near Oak Ridge, Tennessee until 1985. This site is now

being decontaminated and decommissioned, and storage cylinders have been moved to 

other sites, such as Portsmouth. Since 1992, uranium enrichment activities have been

performed by U.S. Enrichment Corporation (USEC), a private company that was created in 

1992 as a wholly owned government corporation and then privatized in 1998. 

2

DOE’s Phosgene Characterization Study reported 2,544 cylinders that were suspected of 

containing phosgene. Thirty-five of those cylinders were removed from consideration 

because they were not relevant; for example, some were not the type of cylinder in 

question. We chose not to report on these 35 cylinders, reporting instead on the 2,509

relevant cylinders. 

Page 2 GAO-07-712 Phosgene Contamination
This investigation was conducted collaboratively by DOE and a 

contractor, Uranium Disposition Services (UDS), which was tasked with 

analyzing and reporting on possible phosgene contamination and also with 

maintaining the storage cylinders and constructing the facilities to convert 

depleted uranium.3

 In April 2006, DOE completed its investigation,4

concluding that phosgene, if present, would not react with uranium 

hexafluoride and that the uranium storage cylinders would not contain 

enough residual phosgene to harm the public outside site boundaries, that 

is, no closer than 200 meters from the cylinders.5

 DOE also concluded that 

the small quantity of residual phosgene it deemed safe for the public 

would also pose no harm to workers, who would be protected under 

existing safety procedures, and not threaten the depleted uranium 

conversion facilities at Portsmouth, Ohio, and Paducah, Kentucky. 

Given the potential safety risks, the Conference Report accompanying the 

Fiscal Year 2006 Energy and Water Development Appropriations Act6

directed us to provide an independent review of possible phosgene 

contamination of DOE’s uranium storage cylinders. This report discusses 

(1) the adequacy of DOE’s investigation of potential harm to workers and 

the public from phosgene contamination of the storage cylinders and 

(2) whether possible phosgene contamination of storage cylinders could 

threaten the depleted uranium treatment facilities after conversion 

operations begin at the Portsmouth and Paducah sites. 

To determine the adequacy of DOE and UDS’s investigation of potential 

harm to workers and the public from possible phosgene contamination of 

uranium storage cylinders, we reviewed the DOE Inspector General’s 

workpapers and interviewed officials to understand their preliminary 

findings. We also interviewed officials at the Defense Nuclear Facilities 

Safety Board and U.S. Enrichment Corporation (USEC). To identify what

actions DOE and UDS were required to take to address worker and public 

Scope and 

Methodology 

 3

In addition to DOE and UDS officials, officials from Bechtel Jacobs Corporation were 

involved in investigating possible phosgene contamination of uranium storage cylinders 

formerly stored at DOE’s Oak Ridge site. 

4

Department of Energy, Depleted Uranium Conversion Project, Phosgene Characterization 

Study, DUF6-G-RGN-008, rev. 1 (Washington, D.C.: April 2006). 

5

DOE and UDS determined that, should a cylinder rupture, 1.2 grams or less of residual 

phosgene present in a cylinder would not harm people standing 200 meters or more from

the ruptured cylinder. 

6

H.R. Rep. No. 109-275, at 150 (2005). 

Page 3 GAO-07-712 Phosgene Contamination
safety in light of the possible presence of phosgene, we reviewed federal

safety requirements set out in the Code of Federal Regulations7 and DOE 

guidance.

8

 In addition, we spoke with senior DOE safety officers to clarify 

the requirements and expectations of DOE safety investigations. To learn 

what actions DOE and UDS took to address the potential presence of 

phosgene, we reviewed DOE’s Phosgene Characterization Study and 

supporting documents and interviewed DOE and UDS officials who 

conducted the investigation. To determine the reliability of the data DOE 

and UDS used in determining whether cylinders posed harm to workers or

the public, we reviewed a stratified random sample of 250 cylinders from 

the 2,509 cylinders in question and reviewed all the available records for 

each cylinder. We visited the cylinder storage yards at the Paducah and 

Portsmouth sites to view some of the cylinders in our sample and to 

examine cylinder records. We found that DOE and UDS had generally 

interpreted the cylinder record information correctly and consistently and 

that their data were sufficiently reliable. 

To assess DOE and UDS’s scientific assumptions and conclusions in their 

investigation of possible phosgene contamination, we assembled a panel 

of experts from outside DOE to review DOE’s final report and supporting 

documents. To select experts, we used an iterative process (often referred 

to as the “snowball sampling” technique) to identify scientists outside DOE 

who had experience or expertise in phosgene, nuclear material, or both. 

Through recommendations by knowledgeable government agency 

officials, we first identified a small number of experts. We asked these 

experts to participate in the panel and to provide names of other experts 

with knowledge of phosgene or nuclear material. We continued soliciting 

names until we determined that we had appropriate coverage of the topic 

areas. We did not limit our search to government agencies but solicited 

recommendations for experts from government, private, academic, and 

international organizations. The scientists we identified with the necessary 

expertise were all government scientists. Table 1 lists the resulting panel 

of seven experts. 

 7

10 C.F.R. part 830, subpart B: Safety Basis Requirements. 

8

Department of Energy, DOE Standard: Review and Approval of Nuclear Facility Safety 

Basis Documents (Documented Safety Analyses and Technical Safety Requirements),

DOE-STD-1104-96, Change Notice No. 1, May 2002; Implementation Guide for Use in

Addressing Unreviewed Safety Question Requirements, DOE G 424.1-1, October 2001; and 

Implementation Guide for Use in Developing Documented Safety Analyses to Meet 

Subpart B of 10 C.F.R. 830, DOE G 421.1-2, October 2001. 

Page 4 GAO-07-712 Phosgene Contamination
Table 1: GAO’s Expert Panelists, Titles, and Affiliations

Name Title Affiliation

Dr. Frederic Berg Supervisory Research Chemist U.S. Army Edgewood Chemical and Biological Center 

Dr. John F. Kalinich Principal Investigator, Research

Biochemist 

Armed Forces Radiobiology Research Institute 

Dr. Tadeusz Kleindienst Research Physical Scientist U.S. Environmental Protection Agency, National Exposure 

Research Laboratory 

Dr. Urmila Kodavanti Research Biologist U.S. Environmental Protection Agency, Experimental

Toxicology Division, Pulmonary Toxicology Branch 

Dr. David McClain Research Biochemist Armed Forces Radiobiology Research Institute 

Dr. Alfred Sciuto Research Physiologist, Branch Chief U.S. Army Medical Research Institute of Chemical Defense

Mr. William Troskoski Senior Chemical Engineer Nuclear Regulatory Commission, Office of Nuclear Materials 

Safety and Safeguards 

Source: GAO.

Panelists were given DOE and UDS’s final report on the investigation and

the report’s attached supporting documents, in addition to information we 

collected on uranium enrichment from scientists at USEC who work 

directly with the uranium enrichment process. DOE and UDS officials 

reviewed these documents for completeness and accuracy. The panelists 

met to discuss their own analyses and conclusions and continued 

discussions via e-mail and telephone calls. 

To determine whether possible phosgene contamination of uranium 

storage cylinders could threaten the depleted uranium treatment facilities, 

we assessed documentation on the facilities’ operations and interviewed 

officials at UDS and the Nuclear Regulatory Commission. The expert panel 

we assembled reviewed the conversion process and discussed whether the 

facilities would be threatened by phosgene and how the conversion 

process would affect phosgene. Finally, to corroborate the information we

gathered, we interviewed officials at UDS and the Nuclear Regulatory 

Commission who are familiar with the conversion facilities and the 

equipment used to process the uranium storage cylinders. We performed 

our work in accordance with generally accepted government auditing 

standards from March 2006 through April 2007. 

The experts we consulted confirmed that DOE and UDS’s investigation of 

possible phosgene contamination was flawed because, among other 

things, it did not explicitly document that phosgene would not harm 

workers near the storage cylinders. It was not until February 2007, after 

we brought this weakness to DOE and UDS’s attention that they provided 

Results in Brief 

Page 5 GAO-07-712 Phosgene Contamination
supplemental information that addressed worker safety. Until then, DOE 

and UDS believed, but did not explicitly document, that existing worker 

safety procedures were adequate to protect workers from the possible 

presence of phosgene. Regulations governing how DOE and its 

contractors should conduct operations involving hazardous materials 

explicitly call for the contractor to prepare documented safety analyses 

that establish hazard controls necessary to ensure adequate protection of

workers, the public, and the environment. The regulations require DOE to 

take appropriate action to address a newly identified hazard, such as 

possible phosgene contamination. Our panelists agreed that DOE and 

UDS’s investigation demonstrated that phosgene would not be present in 

quantities that could harm members of the public passing by or living near 

the DOE sites—at a distance of 200 meters or more from the cylinders—

where uranium is stored or treated. 

The experts also agreed, however, that DOE and UDS failed to document 

that the same quantities of phosgene that would not harm the public 

would also not harm workers directly involved in handling and 

maintaining the cylinders. Although DOE and UDS officials stated that 

they systematically analyzed the potential consequences to workers of 

phosgene in uranium storage cylinders, they did not explicitly document 

their analysis or conclusions, creating a weakness in their investigation. In

particular, we found no record of their assumptions, analysis, or results. 

DOE and UDS officials reasoned that because the uranium hexafluoride in 

the cylinders was more dangerous than the possible presence of phosgene, 

the existing safety procedure—known as “see and flee”—was adequate to

protect workers from phosgene. Specifically, “see and flee” directs 

workers to evacuate the area when they see any sign of a cylinder rupture. 

DOE guidance instructs DOE and its contractors to document all support 

for safety investigations to allow independent reviewers to assess the 

adequacy of analyses and conclusions. DOE’s guidance also calls for 

independent review of investigation results by officials who are not 

directly involved in the investigation. In this case, however, reviewers may 

have been too familiar with the investigation to provide a review that was 

sufficiently independent to identify and correct this weakness. In February 

2007, DOE and UDS issued a supplement to the original investigation 

report, which supported their earlier assertion that existing safety 

procedures would protect workers near the uranium storage cylinders 

from residual phosgene, and our expert panel concurred. In our view, DOE 

and UDS were fortunate that their undocumented assumptions proved 

correct and existing safety procedures had been sufficient to protect 

workers throughout the investigation. 

Page 6 GAO-07-712 Phosgene Contamination
The experts with whom we spoke agreed that any phosgene present in 

uranium storage cylinders would not threaten the depleted uranium 

conversion facilities under construction at Portsmouth and Paducah, for 

two reasons. First, at the start of the conversion process, cylinders 

containing depleted uranium hexafluoride will be placed inside pressure 

vessels, where their contents will be heated and liquefied. According to 

our expert panel and officials from DOE and UDS, the pressure vessels are 

designed to withstand and contain any leak from a cylinder, so that if 

phosgene were present, it would not affect either the pressure vessels or 

the facilities. Second, during subsequent steps in the conversion process, 

any phosgene that was processed with the depleted uranium hexafluoride 

would be destroyed. Specifically, our expert panel and DOE and UDS 

officials all agreed that the extreme heat would destroy phosgene. In

addition, the water vapor added during the process would react with any 

phosgene present to form compounds, including carbon dioxide, that 

would not threaten the facilities. 

We recommend that DOE better ensure that its safety investigations follow 

agency guidelines and are technically adequate, in particular, by making 

use of reviewers who are independent of the investigations being done and 

who will provide objective evaluations of the investigations’ methods and 

resulting findings and conclusions. 

DOE commented on a draft of this report and generally agreed with our 

conclusions that neither workers nor the public would have been at risk 

from potential phosgene contamination. DOE did not comment on our 

recommendations. DOE took exception to our findings that its 

assessments of worker safety and of the fate of phosgene in the 

enrichment process were inadequately documented, stating that explicit

documentation was unnecessary. Our panel of technical experts, however, 

concluded that without explicit documentation of these critically 

important analyses, DOE could not adequately demonstrate that workers 

would not be harmed by the potential presence of phosgene. DOE also 

took issue with our finding that its review of the investigation was not 

sufficiently independent, stating that its investigation was reviewed by 

four officials who had no direct connection to the investigation. 

Nevertheless, according to documents previously provided to us by DOE, 

we believe that two of these officials, who had approved investigation 

plans and provided direction to the investigation, were not sufficiently 

independent to provide an objective review of the quality or results of that 

investigation. 

Page 7 GAO-07-712 Phosgene Contamination
Created in 1977 from diverse agencies, DOE manages the nation’s nuclear 

weapons production complex, cleans up the environmental legacy of 

nuclear weapons development, and conducts research in both energy and 

basic science. DOE carries out its work at numerous sites and facilities 

around the country, primarily through organizations that manage the 

facilities and implement program and project activities under contract to 

DOE. The department has established an extensive network of field offices 

to directly oversee the work of these contractors. DOE’s 

Portsmouth/Paducah Project Office, under the Office of Environmental 

Management, is responsible for cleanup and depleted uranium conversion 

at the Portsmouth and Paducah sites.

Background 

The United States began processing uranium—a radioactive heavy metal 

that is mined and extracted from ore—before the Manhattan Project gave 

rise to the first atomic bomb in the 1940s. Subsequently, DOE and its 

predecessor agencies continued to process uranium as fuel for 

commercial nuclear reactors. A key step in this process is uranium 

enrichment, which increases the concentration of uranium-235, the form 

of uranium that undergoes fission to release enormous amounts of energy.9

Uranium enrichment involves combining uranium with the chemical 

fluorine to form uranium hexafluoride. Radioactive and extremely 

corrosive, uranium hexafluoride reacts with water and can burn the skin, 

eyes, and internal organs.

Uranium hexafluoride and depleted uranium hexafluoride (the material 

left over after uranium enrichment) are currently stored in steel cylinders. 

In all, approximately 700,000 tons of uranium hexafluoride is stored in 

about 63,000 cylinders at storage yards on the Paducah and Portsmouth 

sites (see fig. 1). A cylinder surveillance and maintenance program 

includes regular inspections to check the integrity of cylinder walls, 

valves, and plugs; replacement or reattachment of nameplates (which are 

vital for cylinder identification and tracking); and repair of any defective 

valves or plugs. 

 9

Natural uranium, the raw material required for the uranium enrichment process,

comprises several isotopes—forms of the same element with different atomic weights. 

Uranium ore consists mostly of uranium-238 and less than 1 percent uranium-235, the 

fissile isotope used in nuclear reactors and nuclear weapons. To be usable as reactor fuel, 

uranium must be enriched so that the proportion of uranium-235 exceeds 1 percent;

commercial nuclear fuel is typically enriched to 3 to 5 percent. 

Page 8 GAO-07-712 Phosgene Contamination
Figure 1: Uranium Storage Cylinders at DOE’s Paducah Site 

Source: DOE Inspector General.

Ultimately, DOE plans to convert the stored depleted uranium 

hexafluoride into uranium oxide, a more stable chemical form for longterm storage. UDS is constructing two depleted uranium hexafluoride 

conversion facilities, one each at Paducah and Portsmouth. Scheduled to 

begin operating in 2008, the facilities together will be able to process a 

total of about eight cylinders of depleted uranium hexafluoride per day. 

DOE estimates that once the conversion facilities begin operating, it will 

take approximately 25 years to convert its existing stockpile of depleted

uranium hexafluoride. 

Historically, because of national security concerns, DOE and its 

predecessors have not been externally regulated for worker or nuclear 

facility safety; rather, DOE relies on its own internal system of oversight 

and controls to hold its contractors accountable. DOE’s primary approach 

to regulating its contractors to ensure public health and safety and the 

safety of workers at nuclear facilities is to incorporate the requirements of 

DOE regulations and directives, including policies, orders, and standards, 

into contracts. Among other requirements, DOE regulations require 

Page 9 GAO-07-712 Phosgene Contamination
nuclear facilities to maintain a master document, called a documented 

safety analysis, that analyzes hazards and describes the controls necessary 

to ensure that workers, the public, and the environment are adequately 

protected. The documented safety analysis and hazard controls are 

referred to as a safety basis. The contractor must submit a safety basis to 

DOE for review and approval; update the safety basis to keep it current 

and reflect changes in the facility itself, its work, or the hazards present; 

and submit the updated document (or a letter stating that there have been 

no changes) to DOE once a year thereafter. If a new hazard is discovered, 

the regulations direct contractors to take immediate steps to ensure the 

facility’s safety and to notify DOE. In addition, the contractor must 

conduct and submit to DOE a safety evaluation of the new hazard. 

An October 2000 report by DOE’s Office of Environment, Safety, and

Health informed DOE that some 30-inch diameter cylinders acquired from

the Army, now used to store uranium hexafluoride, previously contained 

phosgene. A chemical not found in nature, phosgene, or carbonyl chloride 

(COCl2

), was used as a chemical weapon in World War I and stockpiled by

the U.S. Army Chemical Warfare Service in World War II; at present, it is 

used to make plastics, pesticides, and even pharmaceuticals. At room 

temperature, phosgene is a colorless gas heavier than air, with an odor of 

musty hay; in the presence of moisture, it may form a white cloud. 

According to the National Institute for Occupational Safety and Health, 

phosgene presents an immediate threat to life and health at a 

concentration of about 2 parts per million. When the chemical comes in 

contact with moisture on the skin or in the respiratory tract, it reacts to 

form hydrochloric acid, which, like uranium hexafluoride, burns human 

tissues.10 With uranium storage cylinders used in the conversion process, 

DOE’s Inspector General raised a concern that some 30-inch cylinders 

could possibly contain phosgene and could enter the depleted uranium 

conversion facilities for processing. 

After DOE’s Inspector General issued its warning about possible cylinder

contamination from phosgene, DOE and UDS conducted an investigation

to determine the extent to which the cylinders received from the Army 

 10The severity of a chemical’s toxic effect depends on a person’s total exposure to that

chemical, that is, the concentration of the chemical multiplied by the duration of exposure.

For phosgene, exposure to a concentration of 30 parts per million for 1 minute (or 3 parts 

per million for 10 minutes) damages the lungs, exposure to 150 parts per million for 1

minute causes the lungs to fill with fluid, and exposure to 300 parts per million for 1 minute 

or more can kill.

Page 10 GAO-07-712 Phosgene Contamination
were contaminated. For each cylinder, they applied one of three criteria to 

establish that the cylinder could contain no more than a trace amount of 

phosgene. First, they found that if past practices to prepare storage 

cylinders for use in the uranium enrichment process had been consistently 

followed, these practices should have eliminated any phosgene that might 

have been present. These practices included cleaning the cylinders—

washing their interiors with corrosive chemicals and rinsing them with 

water––and pressure testing them to ensure they were structurally sound. 

DOE had documents demonstrating that 176 of the 2,509 cylinders had 

been cleaned or pressure tested after DOE received them from the Army. 

DOE was therefore able to clear these 176 cylinders of suspicion on the 

basis of this first criterion. Second, DOE and UDS calculated that if the 

storage cylinders had been filled with and emptied of uranium 

hexafluoride at least once, any residual phosgene in the cylinders should 

have been reduced to quantities too small to harm the public. DOE cleared 

2,296 cylinders on the basis of this second criterion.11 Third, DOE and UDS 

determined that if a cylinder had a hole in it—for example, where a valve

was removed from the cylinder and the resulting hole was left 

uncovered—residual phosgene would have dissipated completely from the 

cylinder. DOE cleared another 12 cylinders with open holes, on the basis 

of this third criterion. Finally, DOE and UDS sampled and analyzed the 

contents of the last 25 cylinders and did not detect phosgene at or above 

the residual quantity they deemed safe for the public. 

DOE and UDS’s investigation of possible phosgene contamination was 

flawed because, among other things, it did not explicitly document that 

phosgene would not harm workers near the uranium storage cylinders. 

Under federal regulations and DOE guidance, DOE and its contractors are 

to assess safety risks to workers and the public. Although DOE considered 

worker safety, it did not explicitly document its analysis or conclusions. It 

did adequately assess and document its conclusions for public safety. In

response to our review, DOE and UDS provided supplemental information 

that the experts we consulted found sufficient to support DOE’s initial 

assertion that existing safety procedures had protected workers from 

harm throughout the investigation. 

DOE’s Investigation of 

Possible Phosgene 

Contamination Did 

Not Adequately 

Document Analysis of 

Worker Safety 

 11DOE and UDS originally identified 182 cylinders that met the first criterion and 2,290 

cylinders that met the second criterion. During our review, however, 6 cylinders were

found to not meet the first criterion; they were subsequently cleared of suspicion by DOE

under the second criterion. As a result, 176 cylinders met the first criterion, and 2,296 met

the second. The next section discusses this difference in more detail. 

Page 11 GAO-07-712 Phosgene Contamination
DOE Did Not Explicitly 

Document Its Analysis of 

the Safety Risk to Workers 

from Possible Exposure to 

Phosgene 

According to the experts we consulted, the original investigation was 

flawed because DOE and UDS did not explicitly document that workers 

would face no harm from small quantities of phosgene that could be 

present in uranium storage cylinders. Federal regulations and DOE 

guidance direct DOE and its contractors to analyze safety risks to workers, 

the public, and the environment to ensure that they are adequately 

protected from hazardous materials and conditions. To do so, each DOE 

facility must maintain a comprehensive documented safety analysis that 

details potential hazards and appropriate safety procedures to mitigate 

those hazards. If a new hazard is discovered that is not addressed in the 

existing documented safety analysis, federal regulations direct DOE and 

its contractors to take action to place or maintain the facility in a safe 

condition until a safety analysis is completed and submitted to DOE for 

approval. 

According to DOE guidance and senior regulatory officials, a safety 

analysis conducted in response to a new hazard must analyze appropriate

accident conditions, derive or identify procedures sufficient to ensure the

safety of workers, and demonstrate the adequacy of those procedures to 

maintain the work environment at an acceptably low level of risk. In 

addition, guidance specifies that safety analyses should be well 

documented to allow independent reviewers to assess the adequacy of the 

analysis and its conclusions. The officials stated that the analysis should 

be rigorous, include quantitative and qualitative reasoning, and identify 

and defend assumptions. 

In this case, DOE and UDS conducted an investigation of the possible 

presence of phosgene contamination in uranium storage cylinders because

they recognized the possibility that workers and the public might be in 

danger if phosgene were present in the cylinders. For example, if an 

accident occurred in the uranium storage cylinder yard and a cylinder 

containing phosgene ruptured, workers and the public could suffer serious 

harm if they inhaled phosgene gas.12 Through their investigation, DOE and 

UDS demonstrated that only small amounts of phosgene could be present 

in the uranium storage cylinders. All members of our expert panel 

reviewed and concurred with this finding. Nevertheless, the expert panel 

raised concerns that DOE did not specify whether or how workers 

 12The uranium hexafluoride stored in the cylinders is also very dangerous to workers, but 

safety procedures are in place to protect workers from uranium hexafluoride if a cylinder 

were to rupture. 

Page 12 GAO-07-712 Phosgene Contamination
conducting operations directly adjacent to the cylinders would be 

protected from harm if phosgene accidentally escaped from a cylinder. 

When we related our expert panelists’ concerns about the possible effects 

of phosgene on workers, DOE and UDS officials stated that they had

assessed worker safety during the investigation and decided that workers 

would not be harmed by the possible presence of small amounts of 

phosgene. DOE and UDS officials stated that the first-response safety 

procedure to protect workers from uranium stored in the cylinders—

termed “see and flee”—calls for immediate evacuation of the area around 

a ruptured cylinder. They reasoned that since this procedure was 

sufficient to protect workers against large quantities of uranium 

hexafluoride if a cylinder ruptured and the contents escaped, it would also 

be sufficient to protect workers from small amounts of phosgene. 

DOE and UDS did not, however, explicitly document or support their 

inference that workers would be protected by the “see and flee” safety 

procedure. During their investigation, DOE and UDS considered worker 

safety and inferred that “see and flee” would protect workers from the 

possible presence of phosgene. Contrary to guidelines, however, they did

not document a thorough analysis demonstrating that “see and flee” was 

adequate to protect workers until we brought the matter to their attention. 

Although DOE and UDS officials stated that they had systematically 

analyzed the potential consequences of the presence of phosgene in 

uranium storage cylinders to worker safety, they were unable to provide 

any documentation of their analysis, such as assumptions, reasoning, or 

results. The phosgene investigation did undergo review, but the lack of 

documentation of DOE and UDS’s consideration of worker safety made it 

impossible for reviewers to assess the adequacy of this consideration and

thus allowed a key element of the investigation to pass without inspection. 

In addition, DOE’s review of the phosgene investigation may not have 

been sufficiently independent. Senior DOE regulatory officials stated that

reviewers should not be involved in the investigation under review; in this 

case, however, officials involved in the investigation also served as 

reviewers. DOE reviewers may have been too familiar with the project to

provide a sufficiently independent assessment of the investigation. DOE’s 

review allowed a weakness—the unsupported inference that existing 

safety procedures would protect workers—to persist in DOE’s

investigation of possible phosgene contamination. Thus DOE and UDS 

believed, without explicitly documenting, that existing worker safety 

procedures were adequate to protect workers from the possible presence 

of phosgene.

Page 13 GAO-07-712 Phosgene Contamination
Ultimately, in February 2007, DOE and UDS issued a supplement to the 

original investigation report, which documented the assumptions, 

reasoning, and calculations used to reach the conclusion that existing 

safety procedures would protect workers from the possible presence of 

phosgene. All members of our expert panel agreed with the conclusions 

presented in the supplement. Therefore, the supplemental information 

showed that, throughout the investigation, workers were protected from 

harmful phosgene exposure by existing safety procedures. 

In addition, we identified two other weaknesses in DOE and UDS’s 

investigation of possible phosgene contamination, which they addressed 

during our review. Specifically: 

• DOE and UDS assumed, but did not explicitly document, that any 

phosgene introduced into the uranium enrichment process would be 

destroyed. DOE and UDS did not identify this assumption or support it 

with evidence or analysis during the investigation. This is a key 

assumption because if the uranium enrichment process did not destroy 

phosgene, the gas could have passed through the process and into 

hundreds of thousands of cylinders containing enriched uranium 

hexafluoride and could still be present today. Scientists knowledgeable 

about the uranium enrichment process and the experts we consulted all 

confirmed that DOE and UDS’s undocumented assumption was correct—

phosgene, if introduced into the uranium enrichment process, would have 

reacted with other chemicals in the process and been destroyed, or it 

would have been purged from the process with other waste gases. After 

we discussed this weakness with DOE and UDS, they provided 

supplemental information demonstrating that phosgene would not survive 

the uranium enrichment process. We reviewed the supplemental 

information and found that it adequately supports DOE and UDS’s 

assumption.

• DOE and UDS used records to determine that 181 cylinders had been

pressure tested, which would have eliminated any phosgene that may have 

been present, but records for 6 cylinders lacked sufficient information to 

meet this criterion. According to DOE and UDS’s definition of the 

pressure-test criterion, a cylinder must have information showing that 

(1) it underwent a pressure test and (2) the cylinder was under DOE’s 

control at the time of the test. If a test had been performed while the 

cylinder was still in the Army’s possession, it could have subsequently 

been used to store phosgene. During our review, we identified one 

cylinder that did not have sufficient information to prove that DOE had 

performed the pressure test. After discussing this weakness with DOE and 

UDS officials, UDS conducted its own review of all 181 cylinders and 

Page 14 GAO-07-712 Phosgene Contamination
found 5 additional cylinders that also had insufficient information to meet 

the pressure-test criterion. The available information for all 6 cylinders, 

however, did meet the definition of another criterion, and as a result, DOE 

and UDS concluded that the cylinders posed no harm. 

These two weaknesses created potential vulnerabilities in DOE and UDS’s 

investigation of possible phosgene contamination because if phosgene had 

survived the enrichment process, or if the six cylinders could not have 

passed a different criterion, many cylinders could still contain unknown 

amounts of phosgene today. 

According to the experts we consulted, DOE and UDS conclusively 

demonstrated that the presence of small amounts of phosgene in storage 

cylinders would not harm the public. DOE and UDS followed federal 

regulations and agency guidelines by identifying possible accident 

conditions and applying and documenting a qualitative and quantitative 

analysis consisting of three main steps. First, DOE and UDS determined 

that the closest the public would be to cylinders possibly containing 

phosgene was 200 meters—the shortest distance between the storage site 

boundary and the cylinders. Second, DOE and UDS calculated the 

maximum amount of phosgene that could be released from a cylinder 

without harming a person standing 200 meters away. To do this, DOE and 

UDS used emergency-response planning guidelines that specify the 

maximum airborne concentration of phosgene that nearly all individuals 

could be exposed to for up to 1 hour without experiencing more than mild, 

transient health effects (such as coughing and eye irritation) and 

perceiving only an objectionable odor.13 They then applied a computer 

model to predict the dispersion of phosgene gas from a ruptured cylinder 

and determined that 1.2 grams was the maximum amount of phosgene that 

could be present in a cylinder without harming a member of the public 

200 meters away. Third, DOE and UDS determined that none of the 

cylinders could contain phosgene in excess of this 1.2 gram amount. 

Specifically, DOE and UDS reviewed cylinder records to document that 

the cylinders: 

DOE Did Document Its 

Analysis of the Safety Risk 

to the Public 

 13These emergency response planning guidelines were developed by the American 

Industrial Hygiene Association, a nonprofit organization founded in 1939 that serves the 

needs of environmental health professionals practicing industrial hygiene in industry,

government, labor, academic institutions, and independent organizations. 

Page 15 GAO-07-712 Phosgene Contamination
• had been washed or pressure tested after DOE acquired them;

• had been filled and emptied of uranium hexafluoride at least once, which 

would have removed enough phosgene that only a residual amount (less 

than 1.2 grams) could remain; or 

• had open holes (for example, where a valve had been removed; see fig. 2), 

which would have allowed any phosgene to diffuse harmlessly over time.

DOE and UDS determined that if any one of these criteria were met, the 

amount of phosgene that could remain in a cylinder was 1.2 grams or less. 

For cylinders that did not meet these criteria, DOE and UDS sampled the 

contents to test for phosgene. On the basis of these procedures, DOE and 

UDS determined that phosgene could not be present in quantities that 

would harm the public. 

Figure 2: Cylinder with an Open Hole

DOE and UDS documented their assumptions, reasoning, calculations, and 

results from this analysis and reported them in their April 2006 

investigation report. According to the experts we consulted, DOE and 

UDS’s analysis conclusively demonstrated that the public would not be 

Source: Uranium Disposition Services.

Page 16 GAO-07-712 Phosgene Contamination
harmed from any phosgene that could be present in uranium storage 

cylinders. 

In September 2005, DOE’s Inspector General warned that the introduction 

of phosgene into the conversion process could possibly have catastrophic 

safety consequences. At that time, neither the Inspector General nor DOE 

and UDS knew how much phosgene could be in a cylinder. In the 

investigation prompted by the warning, however, DOE and UDS 

demonstrated that no more than 1.2 grams of phosgene could be present in

a cylinder. DOE and UDS determined that this small quantity of phosgene,

if introduced into the conversion facilities, would not cause a safety 

concern, and the experts we consulted concurred. 

The experts, as well as DOE and UDS officials, cited two main reasons for 

concluding that the conversion facilities would not be threatened if 

1.2 grams or less of phosgene were present in the uranium storage 

cylinders. First, during the conversion process, the cylinders will be placed 

in pressure vessels (called autoclaves) that will heat their contents to 

approximately 200 degrees Fahrenheit. (Fig. 3 summarizes the conversion 

process and what would happen to any phosgene present.) According to 

UDS officials and experts we consulted, these autoclaves are designed to 

withstand any cylinder ruptures and to contain the contents of the 

cylinders, regardless of whether phosgene is present. Specifically, the 

autoclaves are designed to withstand pressures up to 200 pounds per 

square inch and temperatures exceeding 200 degrees Fahrenheit, and their 

interiors are treated with a protective coating that resists heat and 

corrosive chemicals. They would therefore withstand any depleted 

uranium hexafluoride or phosgene that might leak from a ruptured 

cylinder into the interior of the autoclave. Furthermore, if a cylinder did 

rupture, according to UDS officials, sensors in the autoclave would detect

any depleted uranium hexafluoride released. These sensors would alert 

workers, who could then shut down the autoclave and follow safety 

procedures for cleaning it out. 

Second, once the gaseous depleted uranium hexafluoride and phosgene, if 

present, left the autoclave and entered the conversion unit, high 

temperatures and water vapor applied during conversion would destroy 

any phosgene, in addition to converting the uranium hexafluoride to 

uranium oxide and hydrofluoric acid. According to UDS officials, the 

conversion unit will heat the depleted uranium hexafluoride and phosgene 

to temperatures exceeding 800 degrees Fahrenheit as water vapor is 

added. Because phosgene reacts with water and begins to dissociate into 

Possible Phosgene 

Contamination of 

Uranium Storage 

Cylinders Does Not 

Threaten Depleted 

Uranium Conversion 

Facilities 

Page 17 GAO-07-712 Phosgene Contamination
carbon monoxide and chlorine gases below 800 degrees Fahrenheit, any 

phosgene would separate and react with the water vapor, forming carbon 

dioxide and hydrochloric acid, neither of which would threaten the 

conversion equipment. According to UDS officials, the carbon dioxide 

would be vented from the conversion system with other gases through 

exhaust stacks. The hydrochloric acid would also react with the water 

vapor and be purged from the system. Thus, any residual amounts of 

phosgene that may be introduced into the depleted uranium conversion 

process would be destroyed and would not threaten any part of the 

conversion facilities. 

Figure 3: Steps to Convert Depleted Uranium Hexafluoride to Uranium Oxide, with Impact on Phosgene, If Present 

The cylinders are heated to about 200 degrees

Fahrenheit in autoclaves until the depleted uranium 

hexafluoride becomes a gas.

The gas is piped into a conversion unit, which 

operates at over 800 degrees Fahrenheit, and reacts

with water vapor and hydrogen to produce solid 

uranium oxide and hydrofluoric acid.

The uranium oxide and hydrofluoric acid are 

separated, and the oxide is put into cylinders for 

storage; the hydrofluoric acid is also stored before 

being sold commercially. 

Phosgene gas would mix with the gaseous

depleted uranium hexafluoride and move 

with it to the next step.

Phosgene would separate into other 

compounds and react with the water vapor 

to form hydrochloric acid and carbon 

dioxide.

The resulting carbon dioxide and 

hydrochloric acid would be purged from the 

process.

Description of steps in conversion process Major steps in conversion process Fate of phosgene, if present

2

3

1

Sources: GAO and DOE. 

Autoclave

Uranium Acid

oxide

Conversion

unit

In view of DOE’s long history of processing highly radioactive and other 

dangerous materials for use in defense and civilian endeavors, protecting

workers, the public, and the environment is an integral part of 

accomplishing DOE’s missions. In doing so, DOE has guidelines for 

addressing potential hazards to workers and the public, which include an

independent review of safety analyses. Nevertheless, DOE and UDS’s 

Conclusions 

Page 18 GAO-07-712 Phosgene Contamination
investigation of possible phosgene contamination of uranium storage 

cylinders did not follow guidelines for adequately documenting a safety

analysis of the potential harm to workers that phosgene contamination 

might present. Furthermore, we do not believe that DOE had an adequate 

internal review process for assessing this investigation, a process that 

should have but did not identify weaknesses. Specifically, the review 

should have been conducted by reviewers who were independent of the 

investigation and who could have provided an objective evaluation of the 

investigation’s methodology, findings, and conclusions. Although the 

assumptions DOE used in reaching its judgment on possible phosgene 

contamination turned out to be reasonable in this case, DOE may not be 

so fortunate the next time. The same process weaknesses, if undetected in

other situations, could have dangerous consequences. The discovery of the 

possible presence of a potentially hazardous or lethal safety condition, 

such as phosgene contamination, demands a better planned and managed 

review process and assurance that guidelines are followed. 

To ensure the comprehensiveness and technical adequacy of 

investigations of potentially unsafe situations at DOE’s nuclear facilities, 

we recommend that the Secretary of Energy ensure that safety

investigations benefit from a review process that (1) includes reviewers 

who are sufficiently independent of the investigations being done and 

(2) provides objective evaluations of the methodologies being used and 

the findings and conclusions reached.

We provided a draft of this report to DOE for review and comment. In a 

written response, DOE’s Chief Operating Officer for Environmental 

Management agreed with our conclusion that neither workers nor the 

public would have been at risk from potential phosgene contamination of 

depleted uranium cylinders but took exception to our findings of 

inadequacies in DOE’s investigation. DOE did not comment on our 

recommendations. DOE’s comments on our draft report are included in 

appendix I. DOE also provided the February 2007 supplement to its 

investigation that was previously provided to us. We did not, however, 

reproduce the supplement because our draft report already discussed its 

contents. 

Recommendations for 

Executive Action 

Agency Comments 

and Our Evaluation 

In its written comments, DOE expressed the view that three basic 

assertions in our draft report were incorrect, inaccurate, or misleading. 

Specifically, DOE took issue with our findings that DOE’s assessment of 

worker safety was flawed, DOE’s reviewers of the investigation were not 

Page 19 GAO-07-712 Phosgene Contamination
sufficiently independent, and explicit information on the fate of phosgene 

in the enrichment process was not included in the investigation. 

Regarding worker safety, DOE agreed that its investigation did not 

specifically document that potential phosgene contamination would not 

increase health consequences to workers. Nevertheless, DOE argued that 

explicit documentation was unwarranted because it was so obvious to 

those involved in the investigation that the existing safety management 

plan fully protected workers, and the investigation was written by 

technical experts for review and approval by technical experts. We 

disagree. Our expert panel, which consisted of nationally recognized 

technical experts on phosgene or nuclear material, was unable to 

independently draw the same conclusions as DOE because of the lack of 

explicit documentation in DOE’s investigation regarding the effects on 

worker safety of potential phosgene contamination. In our view, this fact 

calls into question DOE’s contention that it was “obvious” that the existing

safety management plan fully protected workers. 

Furthermore, we are concerned about the seemingly lax attitude portrayed 

in DOE’s comments about the need for adequate documentation of 

important safety analyses. DOE asserted that the absence of explicit 

documentation of the analysis and results of its investigation does not 

jeopardize worker safety, just as the presence of explicit documentation 

would not ensure worker safety. Nevertheless, DOE’s own standard for 

reviewing and approving safety documents states that hazards analyses 

should be both “clearly characterized” and “understandable.”

14 Our expert 

panel found DOE’s analyses to be neither clearly characterized nor 

understandable until DOE issued a February 2007 supplement to its 

original report. DOE stated in its comments that such a supplement would 

have been unnecessary had DOE officials been allowed to communicate 

directly with our expert panel. GAO’s standards of evidence, however, 

require that the experts we rely on be independent and objective. To help

ensure their independence and objectivity, the experts on our panel did

not interact directly with DOE or UDS officials, but the experts did review

information provided by those officials about the investigation’s details. 

We worked closely with DOE and UDS officials to ensure that the 

information provided to the expert panel fairly, accurately, and sufficiently 

described the steps DOE and UDS had taken. We also disagree with DOE’s

 14Department of Energy, DOE Standard: Review and Approval of Nuclear Facility Safety 

Basis Documents, DOE-STD-1104-96, May 2002. 

Page 20 GAO-07-712 Phosgene Contamination
characterization of the February 2007 supplement as “simple.” In fact, 

without it—that is, on the sole basis of the documentation from DOE and 

UDS’s original investigation—our expert panel was not convinced of the 

adequacy of DOE and UDS’s worker safety analyses. Thus we maintain 

that the information and analyses included in the February 2007 

supplement should have been included in the original investigation report. 

As our draft report noted, we and our expert panel agree that the 

assumptions DOE used in reaching its judgment on possible phosgene 

contamination turned out to be reasonable in this case. Nevertheless, the 

fact that DOE was fortunate this time does not reduce the need for future 

DOE hazards analyses to be adequately documented to sufficiently 

demonstrate that workers and the public will not be harmed by potential

risks to their safety. In our view, by questioning the need for explicit 

documentation of its analyses, DOE is contending that those outside the 

department should believe DOE’s conclusions on the basis of trust rather 

than on the basis of rigorous, scrupulously documented analyses. We feel 

that, given the potentially deadly results of a phosgene release, workers, 

the public, and Congress deserve better than simply being asked to take

DOE’s conclusions on faith. 

Regarding DOE’s independent review of the investigation, DOE stated in 

its comments that four high-level, technically qualified officials who had 

no direct connection to the investigation provided an independent review 

of its findings. DOE’s argument, however, is misleading because two of 

these reviewers were also named on a list provided to us by DOE during 

our review as staff who provided input on the direction of the 

investigation and who were involved in reviewing and approving 

investigation plans. In our view, staff who have provided direction to an 

investigation are not sufficiently independent to provide an objective 

review of the quality or the results of that investigation. 

Finally, regarding our finding that explicit information on the fate of 

phosgene in the uranium enrichment process was not included in DOE and 

UDS’s investigation, DOE noted that uranium enrichment facilities are 

operated by USEC, which analyzed the fate of phosgene in the enrichment

process and concluded that the gas would not survive. DOE stated that it

was neither necessary nor appropriate for DOE to repeat USEC’s 

assessment. Contrary to DOE’s assertion, our draft report did not argue 

that DOE should duplicate USEC’s analysis of the fate of phosgene in the

enrichment process. Instead, we believe that DOE should have, at a 

minimum, noted in its investigation that USEC had performed such an 

analysis and summarized its results. We agree, and our draft report noted, 

Page 21 GAO-07-712 Phosgene Contamination
that the February 2007 supplement sufficiently documents the conclusion

that phosgene would be destroyed in the enrichment process. 

Nonetheless, as with DOE’s analysis of worker safety, we continue to 

believe that a supplement should not have been necessary at all, because 

the information and analyses explained in the February 2007 supplement 

should have been included in the original investigation report. 

We are sending copies of this report to the Secretary of Energy. We will 

also make copies available to others upon request. In addition, the report

will be available at no charge on the GAO Web site at http://www.gao.gov.

If you or your staff have any questions about this report, please contact me 

at (202) 512-3841 or AloiseE@gao.gov. Contact points for our Offices of 

Congressional Relations and Public Affairs may be found on the last page 

of this report. GAO staff who made major contributions to this report are 

listed in appendix II. 

Gene Aloise 

Director, Natural Resources 

 and Environment 

Page 22 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department Appendix I: Comments from the Department of Energy 

of Energy 

Page 23 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 24 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 25 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 26 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 27 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 28 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 29 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 30 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 31 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 32 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 33 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 34 GAO-07-712 Phosgene Contamination
Appendix I: Comments from the Department 

of Energy 

Page 35 GAO-07-712 Phosgene Contamination
Appendix II: 

A

GAO Contact and Staff 

cknowledgments 

Page 36 GAO-07-712 

Appendix II: GAO Contact and Staff 

Acknowledgments 

GAO Contact Gene Aloise, (202) 512-3841 or AloiseE@gao.gov 

In addition to the individual named above, William R. Swick, Assistant 

Director; James Ashley; Ellen W. Chu; Ryan T. Coles; Doreen Feldman; 

Cindy Gilbert; Cynthia Grant; George Hinman; Wyatt R. Hundrup; Alison 

O’Neill; Laina Poon; Keith Rhodes; Sushil Sharma; and John Stradling 

made key contributions to this report. Also contributing to the report was 

Jena Sinkfield. 

Phosgene Contamination

Staff 

Acknowledgments 

(360673) 
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