Waste Management

By Rob Weber, Projects and Proposals Manager, Central Research Laboratories

Addressing Current Problems

Bag-out operations can pose many issues to the TRU waste handling and disposal process. Among these are operator and facility safety, operational time, excess waste volume, and increased shipping costs to a waste repository.

Historically, removing hazardous waste from gloveboxes has involved using bags for primary containment. This bag-out method can prove tedious, repetitive, and time-consuming to ensure it follows all required safeguards to transfer waste without breaching containment. Layers of bags, yards of tape, and multiple filters are all added to the waste stream to transfer hazardous waste safely from the glovebox into a disposal drum.

Large-scale testing is done on the Spinionic rotating bed reactor system.

We live in a world where we are continually driven to increase efficiency while decreasing costs—to do more with less. The nuclear industry is no different. Developing innovative techniques or adapting creative ideas found in other industries can support that pursuit to reduce cost and, in this case, volumes of waste, while providing program certainty. Such actions build confidence in our industry and allow nuclear power to continue to be part of the narrative of our clean-energy future.

The National Academies of Sciences, Engineering, and Medicine on February 21 released its fourth and final report on its review of possible approaches to treating low-­activity waste at the Hanford Site. The Department of Energy plans to vitrify approximately 56 million gallons of radioactive and chemical waste at the Waste Treatment and Immobilization Plant, which is currently under construction at Hanford. The waste will be separated into high-­level waste and low-­activity waste (LAW) streams before being turned into a solid glass form through vitrification. Not all of the LAW, however, will be vitrified, and the DOE has not determined a treatment method for the excess waste, called supplemental LAW (SLAW).

A report released to the public on February 20 by the Government Accountability Office concluded that maintenance inspections at several contaminated excess facilities at the Department of Energy’s Hanford Site, near Richland, Wash., have not been comprehensive and that there are areas of some facilities that personnel infrequently or never enter, either physically or by remote means, to conduct inspections. The GAO reviewed surveillance and maintenance (S&M) requirements and activities at 18 of Hanford’s approximately 800 excess facilities that require cleanup and found that improvements to the site’s S&M program are needed.

As nuclear power plants age and retire from service, many countries face significant challenges concerning the safe long-term storage and disposal of large volumes of low- and intermediate-level radioactive wastes (L&ILW). In Canada, Ontario Power Generation (OPG) is currently in the process of obtaining regulatory approval for a deep geological repository (L&ILW DGR) for such wastes from decommissioning and refurbishment of its heavy water reactors. OPG is exploring innovative methods and technologies to improve safety and reduce the processing, transportation, and disposal costs of these wastes. The volumes of metallic waste are of particular concern, because when metal corrodes it produces hydrogen that could lead to pressure buildup in the L&ILW DGR.

Heavy water is used both for moderating nuclear fission and transporting heat in CANDU reactors. As a result of heavy water use in these systems, tritium is produced in small quantities from thermal neutron activation of deuterium. The presence of tritium in the heavy water contributes to the radiation dose of the reactor staff and radioactive emission from the reactor facility. Tritium dose is usually controlled through design and operating procedures that minimize leaks and limit exposure to the tritiated water. Many of the CANDU operators have also reduced the operational tritium concentration through detritiation of the heavy water from the reactor. Detritiation is carried out in a centralized facility, such as the Tritium Removal Facility in Darlington, which provides this service to Ontario’s nuclear reactor fleet. Detritiation reduces both tritium emission and dose to workers and the public from reactor operation.

The Nuclear Regulatory Commission is issuing a proposed interpretation of its low-­level radioactive waste disposal regulations that would permit licensees to dispose of waste by transfer to persons who hold specific disposal exemptions. The NRC said that it will consider approval of requests for specific exemptions only if they are for the disposal of very low-­level radioactive waste by land burial. Notice of the proposed interpretive rule was published in the March 6 Federal Register.

Visitors explore the exhibits and interactive displays at the K-25 History Center at Oak Ridge. Photo: DOE

The Department of Energy’s Oak Ridge Office of Environmental Management and its contractor URS/CH2M Oak Ridge hosted a ribbon-­cutting ceremony on February 27 for the new K-­25 History Center on the site of the former uranium enrichment plant. Located next to the original foundation for the K-­25 building, the center was built to honor and preserve the stories of the workers who constructed and operated the K-­25 complex during World War II and the Cold War.

Speaking before the House Appropriations Committee’s Subcommittee on Energy and Water Development on March 3, Rita Baranwal, the Department of Energy’s assistant secretary for nuclear energy, said that the DOE has prepared a request for proposal for an interim storage site for radioactive waste. “The intent is for the basic design of an interim storage facility,” she said.

Following a comprehensive and open national consultation, the United Kingdom’s Radioactive Waste Management (RWM) organization on February 18 published its approach to evaluating possible sites in England and Wales for a deep geological disposal facility. A wholly owned subsidiary of the U.K. government’s Nuclear Decommissioning Authority, RWM will be responsible for the siting, construction, operation, and eventual closure of a disposal facility for the United Kingdom’s high-­ and intermediate-­level radioactive waste.

International Atomic Energy Agency member states operating or having previously operated a research reactor are responsible for the safe and sustainable management of associated radioactive waste, including research reactor spent nuclear fuel (RRSNF). Management includes storage and ultimate disposal of RRSNF, or the corresponding equivalent waste generated and returned following reprocessing of the spent fuel. Currently, there are 259 research reactors operating, planned, or under construction around the world [1]. An additional 147 research reactors are in extended or permanent shutdown, or under decommissioning.

One key challenge to developing general recommendations for RRSNF management options lies in the diversity of spent fuel types, locations, and national or regional circumstances, rather than mass or volume alone, particularly since typical RRSNF inventories are relatively small. Currently, many countries lack an effective long-term strategy for managing RRSNF. Many research reactor organizations know they have responsibility for the spent fuel, however, they do not know how to decide among multiple options for its management. A methodical review and compilation of technology options for RRSNF management is needed.

The gel is applied to an area (left), where it is allowed to work for two to three hours before being removed. The final activity of the cleaned area (right) was counted using HPGe and Ludlum alpha/beta radiation detectors. Photos courtesy of ANL.

Current techniques for radiological decontamination often involve debasing or demolishing structures to contain contaminated dust and haul debris away. This is a costly method of decontaminating buildings and structures. If, however, effective nondestructive methods can be found, significant savings are possible. One such method, based on new research from engineers at the Department of Energy’s Argonne National Laboratory in Lemont, Ill., is now available.