Nuclear Safety: DOE's Investigation of Phosgene Gas Contamination
Was Inadequate, but Experts Conclude That Worker Safety and
Facilities Are Not Threatened (31-MAY-07, GAO-07-712).
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.
-------------------------Indexing Terms-------------------------
REPORTNUM: GAO-07-712
ACCNO: A70079
TITLE: Nuclear Safety: DOE's Investigation of Phosgene Gas
Contamination Was Inadequate, but Experts Conclude That Worker
Safety and Facilities Are Not Threatened
DATE: 05/31/2007
SUBJECT: Accountability
Chemicals
Contamination
Hazardous substances
Health hazards
Nuclear facilities
Nuclear facility safety
Occupational safety
Phosgene
Public health
Safety regulation
Uranium
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GAO-07-712
* [1]Scope and Methodology
* [2]Results in Brief
* [3]Background
* [4]DOE's Investigation of Possible Phosgene Contamination Did N
* [5]DOE Did Not Explicitly Document Its Analysis of the Safety R
* [6]DOE Did Document Its Analysis of the Safety Risk to the Publ
* [7]Possible Phosgene Contamination of Uranium Storage Cylinders
* [8]Conclusions
* [9]Recommendations for Executive Action
* [10]Agency Comments and Our Evaluation
* [11]GAO Contact
* [12]Staff Acknowledgments
* [13]GAO's Mission
* [14]Obtaining Copies of GAO Reports and Testimony
* [15]Order by Mail or Phone
* [16]To Report Fraud, Waste, and Abuse in Federal Programs
* [17]Congressional Relations
* [18]Public Affairs
Report to Congressional Addressees
United States Government Accountability Office
GAO
May 2007
NUCLEAR SAFETY
DOE's Investigation of Phosgene Gas Contamination Was Inadequate, but
Experts Conclude That Worker Safety and Facilities Are Not Threatened
GAO-07-712
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
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
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separately.
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,
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 2,509^2
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. 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.
^1DOE 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.
^2DOE'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.
Given the potential safety risks, the Conference Report accompanying the
Fiscal Year 2006 Energy and Water Development Appropriations Act^6
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.
Scope and Methodology
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 safety in light of the
possible presence of phosgene, we reviewed federal safety requirements set
out in the Code of Federal Regulations^7 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.
^3In 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.
^4Department of Energy, Depleted Uranium Conversion Project, Phosgene
Characterization Study, DUF6-G-RGN-008, rev. 1 (Washington, D.C.: April
2006).
^5DOE 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.
^6H.R. Rep. No. 109-275, at 150 (2005).
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.
^710 C.F.R. part 830, subpart B: Safety Basis Requirements.
^8Department 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.
Table 1: GAO's Expert Panelists, Titles, and Affiliations
Name Title Affiliation
Supervisory Research U.S. Army Edgewood Chemical and
Dr. Frederic Berg Chemist Biological Center
Dr. John F. Principal Investigator, Armed Forces Radiobiology
Kalinich Research Biochemist Research Institute
Dr. Tadeusz Research Physical U.S. Environmental Protection
Kleindienst Scientist Agency, National Exposure
Research Laboratory
Dr. Urmila Research Biologist U.S. Environmental Protection
Kodavanti Agency, Experimental Toxicology
Division, Pulmonary Toxicology
Branch
Dr. David McClain Research Biochemist Armed Forces Radiobiology
Research Institute
Dr. Alfred Sciuto Research Physiologist, U.S. Army Medical Research
Branch Chief Institute of Chemical Defense
Mr. William Senior Chemical Engineer Nuclear Regulatory Commission,
Troskoski 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.
Results in Brief
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 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.
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.
Background
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.
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.
^9Natural 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.
Figure 1: Uranium Storage Cylinders at DOE's Paducah Site
Ultimately, DOE plans to convert the stored depleted uranium hexafluoride
into uranium oxide, a more stable chemical form for long-term 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 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 (COCl[2]),
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 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.
^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.
DOE's Investigation of Possible Phosgene Contamination Did Not Adequately
Document Analysis of Worker Safety
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.
^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.
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 conducting
operations directly adjacent to the cylinders would be protected from harm
if phosgene accidentally escaped from a cylinder.
^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.
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.
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:
o 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.
o 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 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.
DOE Did Document Its Analysis of the Safety Risk to the Public
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:
^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.
o had been washed or pressure tested after DOE acquired them;
o 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
o 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 harmed from any phosgene that could be present in
uranium storage cylinders.
Possible Phosgene Contamination of Uranium Storage Cylinders Does
Not Threaten Depleted Uranium Conversion Facilities
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 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
Conclusions
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
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.
Recommendations for Executive Action
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.
Agency Comments and Our Evaluation
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.
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
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 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.
^14Department of Energy, DOE Standard: Review and Approval of Nuclear
Facility Safety Basis Documents, DOE-STD-1104-96, May 2002.
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, 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 [email protected]. 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
Appendix I: Comments from the Department of Energy
Appendix II: GAO Contact and Staff Acknowledgments
GAO Contact
Gene Aloise, (202) 512-3841 or [email protected]
Staff Acknowledgments
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.
(360673)
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www.gao.gov/cgi-bin/getrpt?GAO-07-712 .
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Highlights of [26]GAO-07-712 , a report to congressional addressees
May 2007
NUCLEAR SAFETY
DOE's Investigation of Phosgene Gas Contamination Was Inadequate, but
Experts Conclude That Worker Safety and Facilities Are Not Threatened
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.
[27]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
References
Visible links
26. http://www.gao.gov/cgi-bin/getrpt?GAO-07-712
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