2.0 THE TRANSURANIC WASTE DISPOSAL STRATEGY
The strategy for disposal of defense-related TRU waste includes
implementation of the necessary regulatory and programmatic activities
to ensure disposal of the maximum allowable inventory, consistent
with statutory and other legal limitations, that can be demonstrated
to be acceptable in compliance evaluations. Several fundamental
elements of the RH-TRU program are currently in the development
stages. The Waste Isolation Pilot Plant Remote-Handled Transuranic
Waste Disposal Strategy document [DOE, 1995d] addresses these
elements and the programs that are supporting development. The
Remote-Handled Transuranic Waste Study addresses only those
aspects of RH-TRU wastes that pertain to the requirements defined
in the LWA. The transportation elements of this program can be
found in the Comparative Study of Waste Isolation Pilot Plant
(WIPP) Transportation Alternatives [DOE, 1994].
RH-TRU disposal elements that are pertinent to this study include
room configuration, waste packaging, shield plugs, and the physical
and radiological characteristics of the RH-TRU waste inventory.
The following subsections discuss the current strategy for CH-TRU
and RH-TRU waste disposal.
2.1 Room Configuration
The waste disposal area within WIPP consists of eight panels,
each containing seven rooms between access drifts. The RH-TRU
wastes will be emplaced in a manner different from that for the
CH-TRU wastes because of packaging, shielding, and loading requirements;
operational equipment; and structural considerations. The current
disposal configuration of the CH-TRU inventory includes emplacement
of the waste packages in disposal rooms that measure 33 ft wide,
13 ft high, and 300 ft long [Sandia WIPP Project, 1992] (see Figure
2-1). The current configuration for RH-TRU disposal includes emplacement
into the walls in horizontal boreholes. These boreholes will be
drilled 4 feet from the floor on 8-foot centers [Sandia WIPP Project,
1992]. There will be a total of approximately 7,955 RH-TRU waste
Figure 2-1 (144k)
A shield plug capping each borehole after emplacement of the RH-TRU
canister in the room wall will provide the necessary shielding
required for worker safety. This shield plug is constructed of
carbon steel and weighs approximately 4,200 pounds. Appendix A
includes a description of the RH-TRU shield plug currently planned
for implementation. The CH-TRU waste inventory will be emplaced
in the disposal rooms following completion of all RH-TRU waste
disposal activities in that room.
2.2 Waste Packaging
CH-TRU waste containers will be transported and received in a
U.S. Nuclear Regulatory Commission (NRC)-certified TRUPACT-II
shipping container. The CH-TRU waste packaging will include 55-gallon
drums, Standard Waste Boxes (SWBs), and Ten Drum Overpacks (TDOs)
[Nuclear Packaging, Inc., 1992]. The SWB is an oblong steel box
that is 37 in. high, 54.25 in. wide, and 71 in. long. The TDO
is a welded-steel right circular cylinder 74 in. in diameter and
74 in. high.
RH-TRU wastes will be received at WIPP in NRC-certified type B
shipping containers. One canister, which holds approximately three
55-gallon drum equivalents of waste, will be emplaced into each
borehole. Each RH-TRU canister is made of 0.25-inch-thick carbon
steel, is 121 in. long and 26 in. in diameter. Appendix A includes
a description of the RH-TRU canister to be used for disposal.
The waste container requirements for WIPP are described in the
WIPP Waste Acceptance Criteria (WAC) [DOE, 1991].
The Waste Isolation Pilot Plant Transuranic Waste Baseline Inventory Report
(WTWBIR) [DOE, 1995e] data gives inventory quantities and waste
material parameters for TRU waste. These data, as well as the
radionuclide inventory, are supplied by the DOE waste generator/storage
sites. Summaries of the radionuclide and non-radionuclide inventories
were obtained from the WTWBIR and will be used in the PA process.
The radionuclide inventories of both CH-TRU and RH-TRU wastes
are determined using (1) nondestructive assay, (2) some destructive
analyses (to detect isotopes that do not lend themselves to nondestructive
analyses or to evaluate waste streams that cannot be effectively
analyzed through nondestructive methods), and (3) on-site accountability
and tracking records of special nuclear materials, which record
any changes of isotopic ratios during processing [DOE, 1995e].
The WTWBIR provides descriptions for the waste material parameters
in TRU waste. The waste material parameters that have been identified
by PA as being potentially significant to WIPP performance are
- Iron-base metal/alloys, aluminum-base metal/alloys, other
metals, and other inorganics.
- Cellulose, rubber, and plastic.
- Solidified inorganic and organic waste.
- Container Materials: Steel, plastic liners, lead, and steel
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