[Federal Register: March 21, 2005 (Volume 70, Number 53)]
[Notices]
[Page 13482-13485]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr21mr05-57]
[[Page 13482]]
=======================================================================
-----------------------------------------------------------------------
DEFENSE NUCLEAR FACILITIES SAFETY BOARD
[Recommendation 2005-1]
Nuclear Material Packaging
AGENCY: Defense Nuclear Facilities Safety Board.
ACTION: Notice, recommendation.
-----------------------------------------------------------------------
SUMMARY: The Defense Nuclear Facilities Safety Board has made a
recommendation to the Secretary of Energy pursuant to 42
U.S.C.2286a(a)(5) regarding the issuance of a requirement that nuclear
material packaging meet technically justified criteria for safe storage
and handling outside of engineered contamination barriers.
DATES: Comments, data, views or arguments concerning the recommendation
are due on or before April 20, 2005.
ADDRESSES: Send comments, data, views, or arguments concerning this
recommendation to: Defense Nuclear Facilities Safety Board, 625 Indiana
Avenue, NW., Suite 700, Washington, DC 20004-2001.
FOR FURTHER INFORMATION CONTACT: Kenneth M. Pusateri or Andrew L.
Thibadeau at the address above or telephone (202) 694-7000.
Dated: March 15, 2005.
John T. Conway,
Chairman.
Recommendation 2005-1 To the Secretary of Energy Pursuant to the 42
U.S.C. 2286a(a)(5), Atomic Energy Act of 1954, As Amended
Dated: March 10, 2005.
Background
In Recommendation 94-1, Improved Schedule for Remediation in the
Defense Nuclear Facilities Complex, the Defense Nuclear Facilities
Safety Board (Board) urged the Department of Energy (DOE) to improve
the packaging and storage conditions of its large inventory of nuclear
materials once used for weapons manufacture. In particular, the Board
recommended that DOE place plutonium metals and oxides in storage
configurations meeting DOE's standard for long-term storage (DOE-STD-
3013-2004, Stabilization, Packaging, and Storage of Plutonium-Bearing
Materials). Some sites applied Recommendation 94-1 to excess materials
only. The Board has continued to evaluate whether other categories of
nuclear materials are stored in a safe manner.
DOE has made progress in the stabilization and storage of its
excess nuclear materials. The storage requirements for other categories
of nuclear materials, however, are not as well defined and controlled.
Specifically, DOE Order 5660.1B, Management of Nuclear Materials, does
not address safe storage requirements. Other than two narrowly focused
standards--DOE-STD-3013-2004 and DOE-STD-3028-2000, Criteria for
Packaging and Storing Uranium-233-Bearing Materials--there is no
explicit DOE-wide requirement to ensure the safe storage of nuclear
materials. Currently, the technical adequacy of packaging--the
combination of containers and other components providing a
contamination barrier--for nuclear materials, including liquids, is
dependent on the safety bases of individual facilities. Typically,
facilities have credited engineered features, such as the confinement
structure and ventilation system, for protecting offsite individuals
and collocated workers. For facility workers, however, the controls are
generally administrative, such as continuous air monitors, personal
protective equipment, periodic contamination surveys, and other aspects
of the radiological control program, in conjunction with proper
evacuation training. In accordance with DOE Standard 3009, Preparation
Guide for U.S. Department of Energy Nonreactor Nuclear Facility
Documented Safety Analysis (DOE-STD-3009-94, Change Notice 02),
accidents that pose the risk of significant radiological exposure to
workers, such as a breached nuclear material storage package, should be
prevented or mitigated using safety-significant controls. The preferred
hierarchy of controls favors engineered, preventive features over
administrative controls.
Establishing packaging requirements for nuclear materials within
the DOE complex requires consideration of a diverse population of
material types for storage for uncertain periods of time. From a safety
standpoint, nuclear material packaging must protect against a number of
challenges that could breach the container and release radioactive
material. Many of the materials of concern generate gases that result
in container pressurization and may be pyrophoric or highly reactive.
The container design must take into account corrosion, oxidative
expansion of stored metal, effects of radiolysis, diurnal pumping, and
damage due to impacts from drops and tooling during handling. The
Board's recent review of nuclear material packaging at Lawrence
Livermore National Laboratory (LLNL) revealed that many of these
insults had not been fully considered when packaging choices were made
for nuclear materials not covered by Recommendation 94-1. In fact, many
of these current packaging configurations are similar to the inadequate
configurations addressed in Recommendation 94-1, and are documented as
being susceptible to eventual failure in the report of the
Recommendation 94-1 Materials Identification and Surveillance Working
Group, entitled Summary of Plutonium Oxide and Metal Storage Package
Failures (LA-UR-99-2896).
In general, the hazards posed by nuclear materials covered under
DOE's Implementation Plan for Recommendation 94-1 are the same as those
for nuclear materials not considered excess. When nonexcess materials
are removed from glovebox confinement for interim storage, relocation
to another work station, assay, or other purposes, the packages are
susceptible to the same types of failures as those addressed in
Recommendation 94-1. The longer the materials are stored, the greater
are the chances that the packaging will fail, especially if the
packaging has not been designed appropriately for the actual duration
of storage. The Board found that approximately 15 percent of the
nonexcess items at LLNL's Plutonium Facility are stored in packaging
more than 5 years old. Some of the older items, previously declared
excess, remain in their existing packaging while awaiting stabilization
and packaging under DOE-STD-3013-2004. This situation emphasizes the
need to establish a technical basis for packaging, such as designating
the time period for which a particular container is confirmed to
perform its function adequately, in conjunction with tracking the age
of containers in use.
Two recent events serve as further reminders of the importance of
using packaging that is properly designed for its function:
An August 5, 2003, event at Los Alamos National
Laboratory's (LANL) Plutonium Facility resulted in multiple workers
receiving plutonium-238 uptakes as a result of the degradation of a
package stored longer than planned. This event is documented in a DOE
Type B investigation report (HQ-EH-2004-1). The release of material and
the resulting contamination and worker uptakes were due, in large part,
to the inadequate packaging of plutonium being stored and handled
outside of a glovebox.
An October 6, 2004, incident at LLNL involved the
accidental drop of a package containing salt-bearing
[[Page 13483]]
plutonium oxide. This event is documented in an Occurrence Reporting
and Processing System report (OAK--LLNL-LLNL-2004-0046). Although no
plutonium was released, this event highlights the need to specify
robust packaging requirements for materials handled outside of a
glovebox.
State of Nuclear Material Packaging
DOE-STD-3013-2004 sets forth requirements for a robust storage
configuration for long-term storage of plutonium-bearing materials. The
requirements ensure containment through a combination of material form,
packaging design, and surveillance of containers. However, the robust,
welded configurations in the standard may not be desirable when a short
storage period is anticipated pending use of the material.
There are no equivalent requirements for interim storage. As part
of its response to Recommendation 94-1, DOE finalized guidance for the
storage of plutonium-bearing materials not packaged for long-term
storage under DOE-STD-3013. This guidance, identified in a January 25,
1996, memorandum from Deputy Secretary of Energy Curtis entitled
Criteria for Interim Safe Storage of Plutonium-Bearing Solid Materials,
provides a technically justified approach to safe packaging and storage
of plutonium-bearing materials for a period of up to 20 years. Although
these Interim Safe Storage Criteria (ISSC) were not intended to apply
to materials in working inventory, much of the guidance remains germane
to storage of all nuclear materials outside of approved engineered
contamination barriers (e.g., gloveboxes or certified shipping
containers).
The ISSC were only implemented for selected excess materials and
were never formally issued as part of the DOE Directives System. In
practice, the sites use a wide variety of packages, many of which do
not meet the ISSC. According to the lessons learned from the DOE Type B
investigation of the worker uptakes at LANL, packages containing
radioactive material should be assumed unsafe until proven otherwise or
the materials are repackaged to current standards. Yet sites continue
to rely on container types that have been used historically, but have
no technically justified safety or design basis. These container types
are generally forms of packaging typically used in non-nuclear
applications (e.g., paint cans, food pack cans). Thus, they are not
designed to protect against the hazards of the nuclear materials they
contain for the duration of storage.
Several commonly used containers and their potential inadequacies
are briefly summarized in an attachment to this Recommendation. Many
other containers are in use for specialized applications.
Remaining Problems
In response to the Board's May 20, 2002, correspondence on safety
of nuclear materials storage, the National Nuclear Security
Administration (NNSA) established the Inactive Actinide Working Group
(IAWG), with the goal of developing a comprehensive approach to the
characterization, packaging, and storage of a subset of nuclear
materials. As presented in a February 7, 2003, letter from NNSA to the
Board, the IAWG was to meet this goal through the development of three
strategies for the following: acceptance and retention of nuclear
materials, material characterization and storage adequacy, and
disposition. The Board has been observing the IAWG's efforts and has
made three observations.
First, a key product of the IAWG effort will be the strategy for
material characterization and storage adequacy. Based on discussions
with IAWG participants, the delivery of this strategy has been delayed,
in large part because of disagreements among member sites on the
requirements necessary for justifying adequate storage. The Board
believes these requirements should provide for sufficient
characterization based on an appropriate combination of analysis and
process knowledge to determine the appropriate packaging.
Characterization information should also be used to develop a
surveillance program prioritized according to expected material and
container risk (including, for example, material type, material form,
and the age and type of container).
Second, in a June 2000 report entitled A Strategic Approach to
Integrating the Long-Term Management of Nuclear Materials, DOE
recognized the need to update the existing DOE Order on nuclear
materials management. In particular, this report urged improvements to
the nuclear materials management process. However, neither the current
Order nor the report explicitly considers storage safety. The Board
believes that DOE should require a technical basis for nuclear material
packaging and storage safety. Efforts to meet this requirement should
take advantage of the knowledge about storage adequacy being developed
by the IAWG, as well as existing guidance, such as the ISSC.
Third, the IAWG strategy does not include other program offices in
the defense nuclear complex, such as the Nuclear Energy, Science, and
Technology (DOE-NE) facilities involved in defense nuclear activities.
Currently, materials and activities in transition between the
facilities of different program offices have the potential to be
overlooked. For example, operators at the Savannah River Site have
begun converting the neptunium-237 solutions covered under
Recommendation 94-1 to oxide and placing the oxide in packaging
intended for 1 year of storage at that site prior to offsite shipping.
The long-term storage of large quantities of neptunium oxide has not
been performed previously in the complex, and the technical basis for
ensuring the safety of such storage is incomplete. Nonetheless, these
materials will be transferred to DOE-NE for use, where they may
continue to be stored in their existing packaging for a period of up to
20 years. In addition, the Board has learned that DOE-NE intends to
assume more direct control of activities involving plutonium-238, which
have to date been performed at NNSA sites. The significant radiological
hazards associated with this material necessitate appropriate storage
containers for the expected storage period. The Board believes the
requirement for a technical basis for nuclear material packaging and
storage should encompass all program offices in the defense nuclear
complex. DOE may wish to consider implementing this requirement for all
program offices, including those outside of the defense nuclear
complex.
The Board is encouraged by other efforts currently under way to
improve nuclear material packaging. As a result of discussions between
the Board's staff and LLNL, the Livermore Site Office, in a December 3,
2004, letter, directed LLNL to develop a technical basis for the
adequacy of storage packages as part of a Special Nuclear Materials
Storage Plan covering ``all packaging activities.'' LLNL replied in a
letter of January 31, 2005, outlining the required activities,
milestones, and funding to develop and implement an approved packaging
and storage program. Implementation of the plan is contingent upon the
availability of key personnel and funding. Likewise, the proposed
Documented Safety Analysis (DSA) for the LANL Plutonium Facility
requires the use of a proposed facility packaging standard and
designates material containers as a safety-related component. However,
the new DSA has been awaiting NNSA approval. In general, these efforts
represent an improvement, but they do not represent a comprehensive
DOE-
[[Page 13484]]
wide effort, and significant differences remain in the quality of the
efforts at individual facilities.
Recommendation
Nuclear material packaging provides the primary containment
boundary to protect facility workers during storage and handling
activities. The Board believes the development of technically justified
criteria for packaging systems for nuclear materials is necessary on a
DOE-wide level. Therefore, the Board recommends that DOE:
1. Issue a requirement that nuclear material packaging meet
technically justified criteria for safe storage and handling. Packaging
should, in general, provide a robust barrier between facility workers
and the stored nuclear materials once they are removed from an approved
engineered contamination barrier. It may be appropriate to include this
requirement in an updated nuclear materials management Order.
2. Identify which nuclear materials should be included in the scope
of the above requirement and then determine the technically justified
packaging criteria needed to ensure the safe storage and handling of
those materials. The scope need not include waste materials, fully
encapsulated forms, or de minimis quantities such as analytical
laboratory samples. The criteria should account for the nuclear
material form and properties, expected future use, and duration of
storage. It may be appropriate for this information to be included in a
packaging Manual.
The ISSC may provide the beginning of a sound technical foundation
for developing such criteria. Although some modifications may be
necessary to make the ISSC more applicable to short-term storage, the
Board believes the basic ISSC principles--for example, the requirement
for a minimum of two contamination boundaries for high-hazard materials
such as plutonium, assurance that leak-tightness is maintained for
materials requiring a sealed environment, ability of the containers to
withstand maximum expected internal pressures, and protection against
common insults such as drops--should be maintained. The criteria should
also include provisions for surveillance programs to verify that the
container and any limited-life components are performing in a manner
consistent with the duration of storage.
3. Prioritize implementation of the improved nuclear material
packaging requirement consistent with the hazards of the different
material types and the risk posed by the existing package
configurations and conditions.
John T. Conway,
Chairman.
Attachment
Selection of Commonly Used Nuclear Material Packaging
Food-Pack Cans
Food-pack cans are thin-walled tinned carbon steel containers used
in the food industry. No additional manufacturing or structural
requirements have been specified for application with nuclear
materials. These cans typically rely on a double-crimped metal-to-metal
closure with a thin layer of sealing compound to provide leak-
tightness. Historically, many sites have reported failures of food-pack
cans. Lawrence Livermore National Laboratory (LLNL) has reported
anecdotal evidence suggesting that none of its food-pack cans have
failed to the point of detectable contamination outside the container
(UCRL-ID-11733). However, this same report states further that some
degree of oxidation was observed in all of the examined food-pack cans
containing plutonium metal, suggesting the lack of an airtight seal.
Leakage of oxygen through nonairtight food-pack cans has been
responsible for a number of container failures reported at other sites,
due to oxidative expansion of plutonium metals (LA-UR-99-2896).
Improvements have been made to the technology, including better
sealing equipment, as discussed in a May 1984 report entitled The
Effectiveness of Corrective Actions Taken to Preclude Events Involving
Tin Cans and Plutonium (RHO-HS-SA-59 P). Some evidence suggests,
however, that these containers still may not be adequate for prolonged
storage of nuclear materials. Approximately half of the sampled lot of
food-pack cans sealed 10 to 14 years earlier at the Hanford Plutonium
Finishing Plant using the improved methodology failed leak testing, and
nearly all showed further indications of a potential lack of seal (LA-
UR-99-3053).
Additional testing performed at Pacific Northwest National
Laboratory confirmed that the performance of food-pack cans is highly
dependent on the quality of the seal (PNL-5591). During these tests, 33
industry-standard food-pack cans were sealed according to federal
specifications. The testing revealed leak rates ranging from less than
10-5 cubic centimeters per second (cc/sec) to more than 2
cc/sec. These findings should receive due consideration when food-pack
cans are used for storage applications in which a hermetic seal is
required. LLNL continues to use food-pack cans as inner and outer
containers for the storage of plutonium metal and oxide, and other
sites may be storing nuclear materials previously packaged in food-pack
cans.
Paint Cans
Paint cans are thin-walled cans with a press-fit lid that are
commonly used to store paint. They have been used as both inner and
outer containers for the storage of some nuclear materials, including
plutonium metal. The press-fit lid is typically placed by hand using a
mallet, which results in a questionable seal lacking any evidence of
quality control. According to a January 16, 1987, LLNL site report
entitled Incident Analysis/Plutonium Burn in Storage Can, oxidation was
found to be common for plutonium metal stored in paint cans (memorandum
from R.H. Condit to K. Ernst). The report goes on to calculate that a 4
micron gap integrated across the seal area would be sufficient to
permit complete oxidation of 100 grams of plutonium metal in 1 year. A
leak of this size can reasonably be assumed to be present in the press-
fit closure; therefore, the adequacy of these cans for nuclear material
storage applications requiring a seal cannot be ensured. Although LLNL
reports that ingress of air is expected because the lid and rim of the
can are not designed to be airtight (UCRL-ID-117333), paint cans remain
approved for use for certain applications at the laboratory. Other
sites may also be storing nuclear materials that were previously
packaged in paint cans.
Taped Slip-Lid Cans
Slip-lid cans are thin-walled cans with a loose-fitting cover that
is often taped. While convenient and inexpensive, the use of these
containers has resulted in several breached storage packages, including
the plutonium-238 package that led to the Type B event at Los Alamos
National Laboratory (LANL). Many nuclear material packages consisting
of nested taped slip-lid cans remain at the Department of Energy's
defense nuclear facilities. By design, these cans were never intended
to serve a containment function. Furthermore, except for tape, a
mechanical closure is absent, resulting in a container that may not be
able to provide even gross retention of the materials within. The
effectiveness of tape in performing this sealing function over time and
under high radiation conditions is poorly understood. For this reason,
the Interim Safe Storage Criteria (ISSC) specifically prohibit
[[Page 13485]]
crediting slip-lid cans as one of the two required contamination
barriers. Yet several sites continue to use this type of packaging. For
nonmetallic plutonium, including items containing plutonium-238, LANL
plans to rely on stainless steel taped slip-lid cans only as an inner
container; currently, however, a large number of items remain at the
laboratory in nested slip-lid cans. Moreover, several varieties of
slip-lid cans continue to be approved for use as inner and outer
storage containers for certain materials at LLNL.
Hagan Can
LANL's Comprehensive Nuclear Material Packaging and Stabilization
Plan approves the use of a standard container known as the Hagan can, a
robust, screw-top container with an O-ring seal and filtered vent. The
Hagan can generally meets the expectations of the ISSC and has
undergone testing to certify its performance (Wickland and Mataya,
PATRAM 98, 1998). However, drop testing was performed at a height lower
than the expected maximum storage height; therefore, additional
analysis or testing is required. Under the proposed Documented Safety
Analysis for LANL's Plutonium Facility, the Hagan can is classified as
a safety-significant engineered feature. The Hagan can appears to be an
appropriate outer package for nuclear material storage, although, as
recognized by LANL, the service life of the Viton (an organic
fluorocarbon compound) O-ring requires verification through a
surveillance program. Currently, Hagan cans are widely used only at
LANL; however, their use may be under consideration at other sites.
Conflat Can
A can fabricated with a Varian-type Conflat flange results in a
hermetically sealed, robust container that can be used to store
plutonium metal. A copper gasket on a bolted flange closure is designed
to maintain a long-term hermetic seal against oxidation of plutonium
metal. This closure type has been standard in the high-vacuum industry
for many years and has been certified to maintain a leak-tight seal
under various temperature and pressure conditions. The Conflat can is
identified in LANL's Comprehensive Nuclear Material Packaging and
Stabilization Plan as the inner container for the storage of plutonium
metal. The use of Conflat cans for storage of other nuclear materials
requiring a sealed environment may also be appropriate. Conflat cans
have been used periodically at some sites for special storage
applications, but their use is not widespread or uniform.
Metal Drums
Several sites commonly use U.S. Department of Transportation (DOT)
Type A containers and similar types of metal drums for overpacking of
packages of nuclear materials for onsite transportation and storage.
These containers have been certified as Type A radioactive material
packages per DOT specifications. For transportation purposes, this
certification usually is limited to a single year. The use of these
containers for interim storage beyond the certification period appears
appropriate, but consideration should be given to periodic inspection
and replacement for limited-life components, such as lid gaskets. The
Criteria for the Safe Storage of Enriched Uranium at the Y-12 Plant (Y/
ES-015/R2) allow interim storage of enriched uranium materials for a
period of up to 10 years in DOT Type A or Type B containers.
Y-12 Prolonged Storage Container
The Y-12 Y/ES-015/R2 criteria specify the use of stainless steel
cans similar to food-pack cans for prolonged low-maintenance storage
for up to 50 years. While the reliance on a single robust barrier for
the storage of enriched uranium may be appropriate, it is unclear
whether the requirement to maintain mechanical and seal integrity
during normal handling includes protection against drops. In addition,
a lid sealant compound is specified in the appendix to Y/ES-015/R2, but
no discussion of its longevity is provided. While fewer radiological
hazards and less chemical reactivity are associated with enriched
uranium than with plutonium and some other nuclear materials, further
testing of these containers would better demonstrate their reliability
for long-term storage. Currently, the Y-12 container specification is
planned for use only at the Y-12 National Security Complex.
Plastic Bags and Bottles
Historically, plastic bags have been relied upon to provide
contamination control for a limited period. Bag materials, which
include polyethylene, polyvinyl chloride, and related polymers, play an
important role in the overall packaging system. Their principal use is
for contamination control during the ``bagout'' operation, when the
nuclear material container is removed from the glovebox. Unfortunately,
some types of bags have proven to be detrimental to the integrity of
packages left in storage for prolonged periods of time. For example,
the radiation-induced degradation of polyvinyl chloride bag material
led to the production of hydrochloric acid, which in turn contributed
to the corrosion and eventual failure of containers that occurred
during the Type B event at LANL. The choice of material also impacts
the generation of radiolytic gas and effectively defines the service
life of a package when the outer container is not leak-tight. In
repackaging campaigns at LLNL, as well as at other sites, such as
Hanford, bags commonly have been found to be in a discolored or
otherwise degraded state (UCRL-ID-117333 and WHC-SD-TRP-067). While
plastic bags have been in use for a long time, little quantitative
information exists on the effects of time, temperature, and radiation
field exposure on maintenance of an effective contamination barrier. It
is recognized that plastic bags may be necessary for contamination
control, but they should not be relied upon as a long-term
contamination barrier.
In some cases, plastic bottles (e.g., safe bottles) have been used
for the storage of solutions containing nuclear materials, especially
enriched uranium, outside of processing equipment. While bottles are
constructed of thicker plastics than are bags, they undergo the same
chemical and radiolytic degradation with time and must be compatible
with the chemical properties of the contained liquids. Furthermore,
whereas bags provide only contamination control, bottles are relied
upon to provide a complete contamination barrier, including structural
integrity. Any reliance on plastic bags or plastic bottles for extended
periods of time should be informed by the available knowledge of
polymer degradation, in combination with information gleaned from
surveillance programs.
[FR Doc. 05-5450 Filed 3-18-05; 8:45 am]
BILLING CODE 3670-01-P