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Title: Transuranic (TRU) Waste Repackaging at the Nevada Test Site

Conference ·
OSTI ID:962581

This paper describes the activities required to modify a facility and the process of characterizing, repackaging, and preparing for shipment the Nevada Test Site’s (NTS) legacy transuranic (TRU) waste in 58 oversize boxes (OSB). The waste, generated at other U.S. Department of Energy (DOE) sites and shipped to the NTS between 1974 and 1990, requires size-reduction for off-site shipment and disposal. The waste processing approach was tailored to reduce the volume of TRU waste by employing decontamination and non-destructive assay. As a result, the low-level waste (LLW) generated by this process was packaged, with minimal size reduction, in large sea-land containers for disposal at the NTS Area 5 Radioactive Waste Management Complex (RWMC). The remaining TRU waste was repackaged and sent to the Idaho National Laboratory Consolidation Site for additional characterization in preparation for disposal at the Waste Isolation Pilot Plant (WIPP), near Carlsbad, New Mexico. The DOE National Nuclear Security Administration Nevada Site Office and the NTS Management and Operating (M&O) contractor, NSTec, successfully partnered to modify and upgrade an existing facility, the Visual Examination and Repackaging Building (VERB). The VERB modifications, including a new ventilation system and modified containment structure, required an approved Preliminary Documented Safety Analysis prior to project procurement and construction. Upgrade of the VERB from a radiological facility to a Hazard Category 3 Nuclear Facility required new rigor in the design and construction areas and was executed on an aggressive schedule. The facility Documented Safety Analysis required that OSBs be vented prior to introduction into the VERB. Box venting was safely completed after developing and implementing two types of custom venting systems for the heavy gauge box construction. A remotely operated punching process was used on boxes with wall thickness of up to 3.05 mm (0.120 in) to insert aluminum bronze filters and sample ports to prevent sparking during penetration. A remotely operated cold-drilling process with self-drilling, self-tapping titanium coated spark-resistant filters was used for boxes with wall thickness of up to 6.35 mm (0.25 in). The box headspace was sampled for the presence of flammable gases. To further accelerate the project schedule, an innovative treatment process was used. Several of the OSBs were re-assayed and determined to be mixed low-level waste (MLLW) which allowed treatment, followed by disposal in the Mixed Waste Disposal Unit at the NTS Area 5 Radioactive Waste Management Complex (RWMC). The MLLW boxes were certified using real-time radiography and overpacked into custom-built polyethylene-lined macroencapsulation containers. The polyethylene-lined lid was welded to the poly-lined box using automatically controlled resistance heating through embedded wiring in the lid. The work was performed under the existing Documented Safety Analysis since plastic welding is accomplished at low temperature and does not introduce the risks of other macroencapsulation processes, such as welding stainless steel containers. The macroencapsulation process for MLLW not only accelerated the schedule by reducing the number of boxes requiring size reduction, but it also resulted in significantly improved safety with as low as reasonable achievable levels of exposure to workers plus reduced cost by eliminating the need to perform repackaging in the VERB.

Research Organization:
National Nuclear Security Administration
Sponsoring Organization:
USDOE
OSTI ID:
962581
Report Number(s):
DOE/NV-1299; TRN: US0902889
Resource Relation:
Conference: Waste Management 2009, Phoenix, Arizona, March 1-5, 2009
Country of Publication:
United States
Language:
English