[DNFSB
LETTERHEAD]
September 14, 2007
The Honorable James A. Rispoli
Assistant Secretary for Environmental Management
Dear Mr. Rispoli:
The Defense Nuclear
Facilities Safety Board (Board) has been following the design and safety basis development for the
Uranium-233 Downblending and Disposition Project in
Building 3019 at Oak Ridge National Laboratory. The Board notes the recent
approval of the Critical Decision (CD)-2/3A milestone as defined in Department
of Energy (DOE) Order 413.3A, Program and Project Management for the
Acquisition of Capital Assets.
The Board agrees with the overall safety strategy as
summarized in the enclosure to this letter but has concerns with the
implementation of this strategy as identified below. The safety-related areas that
need to be addressed as the project progresses
include:
The Board notes that completion of this project will
meet the intent of the Board's Recommendation 97-1, Safe Storage of
Uranium-233. �Providing a disposition
path for this large portion of the uranium-233 in the defense nuclear complex
precludes the need for extensive repackaging and major upgrades to the Building
30 19 storage facility. To ensure safe final disposition of this material, the
Board encourages project personnel to continue their interactions with the
Waste Isolation Pilot Plant so as to meet all
technical and legal requirements for geologic disposal of the downblended material.
Sincerely,
A.J. Eggengerger
Chairman
c: Mr. Gerald G. Boyd
�� Mr. Mark B. Whitaker, Jr.
Enclosure
Enclosure
Uranium-233 Downblending and Disposition Project Summary
The Uranium-233 (U-233) Downblending and Disposition Project is
designed to downblend the vast majority of the
Department of Energy's (DOE) inventory of separated U-233. �The material will be blended with depleted
uranium to less than 1 percent equivalent U-235 enrichment (0.66 percent U-233) in an
aqueous process, then denitrated
to a solid uranium trioxide product. This product will be
packaged in shielded containers for interim storage at Oak Ridge
National Laboratory (ORNL) prior to final disposition. The majority of the downblended material is expected to be
disposed of at the Waste Isolation Pilot Plant, and a small portion at the
Nevada Test Site. Unpackaging, dissolution, downblending, denitration, and
packaging operations will take place in Building 3019 at ORNL. Building 3019 is
a Hazard Category 2 nuclear facility that would be expected
to meet Performance Category 3 requirements. However, certain structures and
components, notably the penthouse on top of Building 3019 and the adjacent 3020
stack, do not meet current site requirements for Performance Category 3.� Calculations show that the stack could
fail and potentially fall onto Building 3019 in certain seismic and wind
events. Additional analyses to identify a risk mitigation strategy are in progress.
The safety strategy for the
U-233 Downblending and Disposition Project relies on confinement
of hazardous materials under normal and accident conditions, use of heavy shielding
to attenuate high radiation fields, and safe geometry and other controls to
prevent inadvertent criticality during handling of fissile material. The
primary material at risk in the facility is the U-233 itself. It is a fissile
alpha emitter with a strong gamma field due to daughter products of impurities.
Significant hazards include fires, natural phenomena events, criticality, and
insults to containers or material-handling equipment. The current Preliminary
Documented Safety Analysis identifies a control set designed to prevent or
mitigate these hazards. The safety classification of the controls has not been finalized because of site boundary changes and continued
revisions to safety documentation. However, the following were
initially recommended as safety-class controls:
There are also numerous
safety-significant controls, including the following:
-� Filters in process cell, vessel, and
laboratory ventilation system
-� Containers and container transfer equipment
-� Passive building and cell confinement (Note: This is under evaluation as a part of a gap analysis being
conducted in
accordance with Recommendation
2004-2, Active Confinement Systems)
Administrative controls to augment facility safety have not yet been fully developed. Certain fire prevention controls and placement of
movable shielding are anticipated to be safety-significant administrative controls.
Project personnel are currently updating safety
documentation, finalizing design efforts,�and planning the procurement of items
requiring long lead times. Additionally, with CD-2/3A having
been approved, dismantlement and removal of existing contaminated
equipment in Building 3019 can be planned and executed.