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Introduction
The purpose of this report is to provide an independent technical review of the U.S. Department of Energy’s (DOE’s) proposed characterization plan for defense-related remote-handled (RH) transuranic (TRU) waste. Remote-handled transuranic waste is defined in Sidebar 1.1.
Transuranic waste is classified as remote-handled (RH) or contact-handled (CH) depending on the radiation dose rate measured at the surface of waste containers. While CH-TRU waste can be safely handled by direct contact, RH-TRU waste requires heavy container shielding or remote-handling equipment. Therefore, the main issues with RH-TRU waste characterization are the potential for worker exposure to radiation and the associated costs.
Because of its radiological hazard, TRU waste requires geologic isolation. Congress designated the Waste Isolation Pilot Plant (WIPP), in southeastern New Mexico, as the nation’s geologic disposal facility for defense-related transuranic waste (U.S. Congress, 1992). Figures 1.1, 1.2, and Sidebar 1.2 provide a schematic representation and a brief description of the WIPP facility. DOE is seeking authorization to dispose of RH-TRU waste in WIPP as part of its commitment to safely manage and clean up contamination from over 50 years of nuclear materials research and production. About 3,800 cubic meters of defense-related RH-TRU waste (corresponding to approximately 1 million curies) is the current estimated volume of RH-TRU waste to be disposed in WIPP.
The U.S. Environmental Protection Agency (EPA) and the New Mexico Environment Department (NMED) are WIPP’s regulatory agencies. In 1998, the EPA, which regulates TRU waste, granted WIPP a Certification of Compliance (referred to as the EPA Certification) with the geologic disposal standards established in Title 40 of the Code of Federal Regulations Part 191 (40 CFR 191). In 1999, the NMED, which regulates hazardous waste disposal under the Resources Conservation and Recovery Act (RCRA), granted WIPP a hazardous waste facility permit (referred to as the RCRA Permit). Regulatory requirements addressing radioactive and hazardous waste will be discussed in Chapter 3.
EPA and NMED authorize only CH- and mixed CH-TRU waste in WIPP. Remote-handled TRU waste is not allowed in this facility because, according to these agencies, DOE does not have an appropriate characterization plan for this type of waste (see Chapter 3).
The EPA Certification and RCRA Permit contain characterization requirements for TRU waste to be emplaced in WIPP. These characterization requirements were negotiated among DOE, EPA, and NMED and they are the basis of the current characterization plan for CH-TRU waste.
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SIDEBAR 1.1 Definition of Transuranic Waste and Classification Transuranic (TRU) waste is radioactive waste containing alpha-emitting radionuclides of atomic number greater than 92, half-lifea greater than 20 years, and activity greater than 100 nanocuries per gram of waste, except for: high-level radioactive waste; waste that the Department of Energy (DOE) has determined, with the concurrence of the Environmental Protection Agency (EPA), does not need the degree of isolation required by the disposal regulations; or waste that the Nuclear Regulatory Commission has approved for disposal on a case-by-case basis in accordance with Title 10 of the Code of Federal Regulations Part 61 (U.S. Congress, 1992). Transuranic waste can consist of sludge or solid material, such as pieces of clothing, tools, and debris. This type of waste was produced during the processing of nuclear materials and continues to be generated in the cleanup of DOE weapons sites. The main alpha-emitting radionuclides in TRU waste (and their respective half-lives indicated in parenthesis) are plutonium-238 (87.7 years), plutonium-239 (24,100 years), plutonium-240 (6,560 years), and americium-241 (433 years). Other long half-life isotopes, such as uranium-233 (159,200 years), uranium-234 (24,600 years), uranium-235 (704 million years), and uranium-238 (4.47 billion years) may also be present in transuranic (TRU) waste. Transuranic waste is classified as contact-handled (CH) or remote-handled (RH), according to the dose rate measured at the container surface. According to Land Withdrawal Act, “the term ‘contact-handled transuranic waste’ means transuranic waste with a surface dose rate not greater than 200 millirem per hour. The term ‘remote-handled transuranic waste’ means transuranic waste with a surface dose rate of 200 millirem per hour or greater” (U.S. Congress, 1992). The legal definitions of CH-TRU and RH-TRU waste do not clearly address container surface dose rates of exactly 200 mrem per hour. Therefore, waste packages approaching 200 mrem per hour are handled directly or remotely, depending on site-specific practices. Transuranic waste is further classified as mixed or non-mixed. Mixed TRU waste contains both radioactive material regulated under the Atomic Energy Act and hazardous waste material regulated under the Resource Conservation and Recovery Act, or RCRA (U.S. Congress, 1976). RCRA is a federal law addressing hazardous waste designed to ensure that the generation, transportation, treatment, storage, and disposal of hazardous wastes are conducted in a manner that protects human health and the environment (EPA, 1994). The statutory definition of hazardous waste is provided in Section 1004(5) of RCRA as follows (EPA, 1994; page 1–3): “A solid waste, or combination of solid waste, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may 1) cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness; or 2) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.” Examples of hazardous waste material are ignitable, corrosive, reactive, and toxic substances. For an overview of the Atomic Energy Act and major environmental laws, including RCRA, the reader may refer to “The Nuclear Waste Primer” (The League of Women Voters, 1993).
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FIGURE 1.1 Schematic representation of the WIPP Facility. The facility will have eight disposal panels, each divided into seven rooms. Only two of the eight panels have been mined to date. SOURCE: DOE (DOE-CBFO, 2000).
To obtain authorization to dispose of RH-TRU waste in WIPP, DOE must request a modification of the EPA Certification and RCRA Permit and present a proposed characterization plan for this type of waste. This proposed characterization plan is the focus of this report.
DOE’s proposed characterization plan for RH-TRU waste consists of the following two documents:
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Document 1: Notification of Proposed Change to the EPA Title 40 CFR Part 194 Certification of the WIPP.
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Document 2: Request for RCRA Class 3 Permit Modification1 to the NMED.
Documents 1 and 2 will often be referred to in this report as the “submittal documents.”
FIGURE 1.2 Plan view of a section of a typical underground disposal area showing CH-TRU and RH-TRU waste emplacement. SOURCE: National Transuranic Waste Management Program, Rev. 2, Figure 3.2.1.1–2 (DOE-CBFO, 2000; page 69).
Document 1 contains EPA regulatory requirements to ensure that the waste emplaced in WIPP falls within the envelope limits required to maintain compliance with radiological disposal standards. Document 2 contains regulatory requirements to ensure that the non-radiological hazardous characteristics of the waste emplaced in WIPP are compatible with RCRA requirements. Documents 1 and 2 also contain additional
information, such as the WIPP’s waste acceptance criteria, transportation requirements, description of surface storage and handling facilities, and waste certification process.
DOE’s proposed characterization plan must address the characterization requirements in the EPA Certification and RCRA Permit in the context of RH-TRU waste. As shown in Chapter 2, this context is different from that of CH-TRU waste because of the different inventories and radiological properties.
EPA and NMED may accept, reject, or propose modifications to the characterization plan and eventually they may authorize RH-TRU waste disposal in WIPP. Once the characterization methods for RH-TRU waste are finalized, it is the committee’s understanding that DOE will produce one document combining all regulatory requirements to help generator sites implement their characterization programs.
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SIDEBAR 1.2 The Waste Isolation Pilot Plant The Waste Isolation Pilot Plant (WIPP), located near Carlsbad in New Mexico, is the nation’s defense-related transuranic waste repository, as designated by Congress in the Land Withdrawal Act of 1992. This Act allows the disposal of 175,564 cubic meters of transuranic waste in WIPP, of which 7,080 cubic meters can be remote-handled transuranic (RH-TRU) waste with a maximum radioactivity of 5.1 million curies. Other legal criteria for WIPP related to RH-TRU waste are discussed in Chapter 3. The WIPP disposal area is located 660 meters below ground in a salt bed, called the Salado Formation (see Figure 1.1). Large salt beds such as this are found only in regions that lack significant flows of groundwater. This deep, relatively dry, underground environment greatly reduces the possibility of waste releases from the repository by natural processes. Moreover, after approximately 200 years, the mined salt will heal and encapsulate the waste, thereby permanently locking it deep beneath the surface (Knowles and Economy, 2000). The underground waste disposal area in WIPP consists of eight panels, each containing seven rooms. Contact-handled transuranic (CH-TRU) waste drums and boxes are being stacked in three layers in the center of each room. Remote-handled TRU waste is currently not authorized in WIPP. Should the U.S. Environmental Protection Agency (EPA) and the New Mexico Environment Department (NMED) allow disposal of RH-TRU waste in WIPP, it will be emplaced inside horizontal boreholes drilled into the walls of each room. Figure 1.2 shows the CH-TRU and RH-TRU waste emplacement configurations. According to WIPP’s design, the diameter of a borehole for RH-TRU waste containers is 76.2 cm and the length is 487.68 cm (DOE-CAO, 1995). A shield plug will cap each RH-TRU waste borehole to provide workers with the necessary protection against radiation. The WIPP has been under study since the mid-1970s and under construction since January 1981. The facility received the first CH-TRU waste shipment in March 1999 and the first mixed CH-TRU waste shipment in September 2000. To date (July 2002), more than 900 shipments of CH-TRU waste from 26 generator sites have been sent to WIPP. After three years of operation, the first panel has been almost completely filled with CH-TRU waste. Because CH-TRU waste now blocks the access to the rooms walls, RH-TRU waste cannot be disposed in this first panel. Emplacement of CH-TRU waste in the second panel is currently scheduled to begin in December 2002. |
1.1 Committee’s Task and its Boundaries
At the request of DOE-Carlsbad Field Office, the National Research Council appointed the Committee on the Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant, referred to as “the committee” in the rest of this report. The committee roster and biographical sketches can be found in Appendix A. The committee’s statement of task is reproduced in Sidebar P.1 of the Preface. The committee followed the examples of criteria listed in the statement of task to assess DOE’s proposed characterization plan.
The committee was asked to provide recommendations, as necessary, for improving the characterization plan’s technical soundness, protection of worker safety and health, and compliance with regulatory requirements. The difficulty of this latter part of the task lies in performing a review of a characterization plan for RH-TRU waste that must show compliance with existing characterization requirements. These requirements exclude RH-TRU waste. Moreover, the approach currently used to characterize CH-TRU waste is different than the approach DOE proposed for RH-TRU waste. It is important to emphasize the distinction between regulatory requirements and the approach to meet such requirements. While the regulatory requirements for the characterization of TRU waste destined for WIPP, established in the EPA Certification and RCRA Permit, apply to both CH- and RH-TRU waste, the waste characterization plans may propose different approaches to address these requirements. The committee evaluated, from a technical point of view, the approach DOE is proposing to characterize RH-TRU waste and how DOE proposes to address regulatory requirements. The committee was not asked to comment on these requirements nor was it asked to determine if the plan complies with the regulatory requirements. The latter is obviously a policy decision belonging to the regulatory agencies.
During this study, the committee reviewed two drafts of Documents 1 and 2, dated July 2001 (DOE-CBFO, 2001a, 2001b) and March 2002 (DOE-CBFO, 2002a, 2002b). The committee provided initial findings and recommendations in an interim report (see excerpt in Appendix C).
The committee did not verify data provided by DOE on RH-TRU waste inventories. Acknowledging the past fluctuations of RH-TRU waste inventory information, the committee assumes that DOE presented the most up-to-date information available. The committee was not asked to identify other potential sources of RH-TRU waste or discuss the origin of RH-TRU waste streams at generator sites.
Also, the committee did not assess the validity of supplementary information supporting the characterization plan, such as the Sandia Inventory Impact Assessment Reports in Document 1 (DOE-CBFO, 2002a; Attachment 2) and Document 2 (DOE-CBFO, 2002b; Supplement 2). The committee did, however, assess how DOE interpreted and used the results of these reports in its characterization plan.
This document is not meant to be a comprehensive review of the entire RH-TRU waste program, which encompasses RH-TRU waste transportation, storage, waste certification, operational safety issues, occupational health and safety regulations, waste generator states’ regulations, waste acceptance criteria, as well as DOE orders. The National Research Council is undertaking a more general study on the characterization of TRU waste (including relevant transportation requirements) and its impact on DOE’s National Transuranic Waste Management Program.
Documents 1 and 2 were submitted to the regulatory agencies on June 28, 2002. The committee did not review the submittal version of these documents; therefore, findings and recommendations in this report apply to the characterization plan as presented in March 2002.
1.2 Organization of the Report
Following this introduction, Chapter 2 contains updated information on life cycle, status, and inventories of RH-TRU waste at selected generator sites. Chapter 3 describes the regulatory context for the disposal of RH-TRU waste. DOE’s proposed characterization plan for RH-TRU waste is described in Chapter 4. Chapter 5 provides the committee’s assessment of DOE’s proposed characterization plan. In December 2001, the committee released an interim report with initial findings and recommendations relevant to the July 2001 draft. These findings and recommendations can be found in Appendix C. DOE’s response to the committee’s interim report is reproduced in Appendix D.
