Transuranic waste and the Waste Isolation Pilot Plant

TRU waste is a type of RAW that contains elements with atomic numbers greater than uranium (DOE, 2009). This waste consists primarily of clothing, tools, rags, residues, soil, debris, and other materials contaminated with plutonium; it may also be mixed with hazardous components. There are two categories of TRU waste: CH TRU waste can be handled by workers under very controlled conditions with no shielding for radioactivity other than the container itself, while RH TRU waste must be handled and transported in lead-shielded containers and casks because it emits more penetrating radiation. CH TRU represents 96% of the total volume of TRU waste to be disposed of at WIPP, while RH TRU makes up the remaining 4%.

Before WIPP opened, 28 DOE sites were storing TRU waste in a variety of configurations, primarily below-grade to contain the radioactive ele­ments while also allowing for its eventual retrieval for disposal. After nearly 20 years of testing, scientific research, engineering and design, and regula­tory permitting, WIPP began receiving CH TRU waste in 1999. In 2006, WIPP received final authorization to begin accepting RH TRU and the first shipment, from INL, arrived in January 2007.

Located 2,150 feet below ground in a 250 million-year-old salt formation, WIPP is the world ’s only operating deep geological repository. An esti­mated 150,000 m3 of CH TRU and 7,000 m3 of RH TRU resulting from US Cold War defense activities will ultimately be disposed of there.

Between 2002 and 2008, the DOE de-inventoried all legacy TRU waste at 14 sites, thereby eliminating associated management costs at these sites as well as environment, safety, and health risks. TRU waste was also removed from facilities at the NNSS, Lawrence Livermore National Laboratory, and Argonne National Laboratory (ANL) so they can support other missions.

As of February 2013, WIPP had received 11,112 shipments of TRU waste since it opened in 1999. These years of experience and a streamlined regula­tory framework have resulted in more efficient and routine operations with each passing year. The DOE has a clear strategy for building on this past success to meet its TRU risk reduction goals:

• characterize a small quantity of waste in Idaho for shipment to WIPP

• expand use of Central Characterization Project (CCP)

• facilitate shipping sites in certifying waste for acceptance at WIPP

• expand number of sites certified for RH shipping

• deploy shielded containers for shipping RH TRU.

This strategy includes expanding the number of sites certified for RH TRU shipping. To support and enhance this strategy, the DOE continues to develop shielded containers for RH TRU lead-lined drums that allow RH TRU waste to be handled, shipped, and potentially disposed of in a manner similar to CH TRU waste. Currently, RH TRU waste is emplaced in bore­holes along the walls of the WIPP repository and CH TRU waste is placed on the floors.

Significant coordination is required for optimal and efficient emplace­ment of RH TRU and CH TRU waste. The use of shielded containers for placement of selected RH TRU waste on the floors of the repository could increase the efficiency of disposal operations at WIPP. The DOE is actively pursuing the necessary regulatory approvals needed to move forward with shipping and disposing of RH TRU waste in shielded contain­ers at WIPP.

Another TRU waste risk-reduction strategy is the characterization of small-quantity TRU waste sites in Idaho for shipment to WIPP. A Record of Decision (ROD) approved in February 2008 allows the DOE to send waste from small-quantity sites to INL for treatment, characterization, and shipment to WIPP, assuming the waste meets INL waste acceptance criteria. This reduces costs by eliminating the need to construct TRU waste treat­ment facilities at sites with small quantities of TRU waste. It also results in faster removal of TRU from these sites and a greater economy of scale for the TRU waste facility at INL.

The DOE is also expanding the use of the CCP at large sites. The project employs a modular waste characterization system consisting of full disposal characterization equipment for both CH TRU and RH TRU waste and a mobile loading system used to place drums of TRU waste into shipping containers for transport to WIPP. CCP has proven successful in character­izing waste more cost effectively through use of a standard suite of proce­dures, quality assurance documents, and equipment.

Another strategy includes the use of TRU waste expert teams to assist generator sites in certification and characterization planning for waste streams that are more difficult to manage, such as those requiring additional documentation, treatment, or packaging. These teams help to ensure all TRU waste is characterized, shipped, and disposed of at WIPP.

The DOE has designed a new cask, TRUPACT-III, for TRU waste pack­aged in large boxes that cannot be shipped in currently available transporta­tion casks due to their size. The strategy to ship and dispose of large-size containers at WIPP also requires the development, deployment, and regula­tory approval of equipment needed to determine the contents of large containers. With this knowledge, the potentially dangerous and costly task of reducing the size of large containers before shipment and disposal at WIPP can be avoided.

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