3
Mixed Waste Regulations

This chapter summarizes the regulations that control U.S. Department of Energy (DOE) mixed wastes and briefly explains the complex regulatory situation as it currently exists. While both the committee and DOE understand that regulations will evolve, this report is necessarily framed by current regulations for characterization of the mixed waste inventory, treatment and disposal requirements, and waste form performance criteria. The U.S. Environmental Protection Agency (EPA), U.S. Nuclear Regulatory Commission (USNRC), Department of Transportation (DOT), and individual states all exert measures of control over treatment, transport, and disposal of mixed waste. As described in this chapter, the range of regulatory approaches and resulting regulations create substantial challenges for the treatment and disposal of mixed wastes.1

The first section of this chapter describes the treatment and disposal regulations. These regulations may directly limit DOE's options for selecting a type of waste form by imposing controls on the methods to produce the waste form or by requiring that is pass specific chemical or physical tests. The regulations may also affect the choice of waste form indirectly by imposing performance criteria on the waste form itself, on

1  

A recent announcement of proposed rulemaking describes strategies that EPA is considering to relieve mixed waste managers from some of the compliance difficulties that arise from dual regulation by EPA and USNRC (EPA, 1999a).



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--> 3 Mixed Waste Regulations This chapter summarizes the regulations that control U.S. Department of Energy (DOE) mixed wastes and briefly explains the complex regulatory situation as it currently exists. While both the committee and DOE understand that regulations will evolve, this report is necessarily framed by current regulations for characterization of the mixed waste inventory, treatment and disposal requirements, and waste form performance criteria. The U.S. Environmental Protection Agency (EPA), U.S. Nuclear Regulatory Commission (USNRC), Department of Transportation (DOT), and individual states all exert measures of control over treatment, transport, and disposal of mixed waste. As described in this chapter, the range of regulatory approaches and resulting regulations create substantial challenges for the treatment and disposal of mixed wastes.1 The first section of this chapter describes the treatment and disposal regulations. These regulations may directly limit DOE's options for selecting a type of waste form by imposing controls on the methods to produce the waste form or by requiring that is pass specific chemical or physical tests. The regulations may also affect the choice of waste form indirectly by imposing performance criteria on the waste form itself, on 1   A recent announcement of proposed rulemaking describes strategies that EPA is considering to relieve mixed waste managers from some of the compliance difficulties that arise from dual regulation by EPA and USNRC (EPA, 1999a).

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--> additional barriers intended to retain the waste, or on the entire disposal system. Performance criteria can include limitations on radionuclide release or on radiation exposure to individuals or populations. The second section of this chapter describes waste acceptance criteria (WAC) and other requirements. The WAC are imposed by each waste disposal facility on waste it receives. Waste cannot be shipped to a facility unless it meets the facility's acceptance criteria. The acceptance criteria generally do not require specific waste forms, but they may indirectly affect DOE's options by controlling the physical and chemical characteristics of waste materials that are received. Treatment and Disposal Requirements The two principal regulatory agencies involved in the treatment and disposal of mixed waste are the EPA and the USNRC. DOE is subject to regulations promulgated by these agencies through the Federal Facility Compliance Act of 1992 (FFCA), which requires federal facilities to comply with the same regulations as non-federal facilities (FFCA, 1992). Thus, in dealing with its mixed waste, DOE's Office of Environmental Management (EM) must comply with EPA regulations for hazardous wastes and with USNRC regulations for radioactive wastes. Further, the FFCA requires DOE to comply with applicable state regulations if they are more restrictive than federal regulations. For the transport of waste materials, DOT regulations must be observed. In addition, DOE has entered into agreements with many states, which may place added constraints on the selection of treatment and disposal options. Because of its importance for DOE mixed waste management, the FFCA is further explained in Box 1. USNRC, EPA, and DOE regulations referred to in the box are described in the subsequent sections of this chapter. U.S. Environmental Protection Agency EPA has developed regulations for hazardous waste management and disposal principally under authority of the Resource Conservation

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--> Box 1 The Federal Facility Compliance Act The Federal Facility Compliance Act of 1992 has played an important role in DOE mixed waste management programs. Two provisions of the FFCA are especially relevant to the issue of mixed waste management. First, the FFCA requires that DOE facilities comply with all federal, state, and local laws and regulations pertaining to hazardous waste. Thus, DOE facilities are subject to the hazardous waste requirements promulgated under the Resource Conservation and Recovery Act. States that have been delegated authority by EPA to manage their own hazardous waste programs have authority over DOE facilities. The FFCA did not alter the separation of Atomic Energy Act (AEA) authorities and responsibilities between DOE and the USNRC. Radioactive waste is defined by the AEA. Thus, the AEA portion of EM's mixed waste is regulated by DOE under terms of DOE Order 5820.2A and forthcoming Order 435.1 that will supersede it. The USNRC has no jurisdiction over defense transuranic (TRU) waste and the Waste Isolation Pilot Plant, but does have jurisdiction over commercial TRU waste (one form of Greater-Than-Class-C waste that must be disposed by DOE with USNRC approval). DOE continues to define low-level waste (LLW) by exclusion [that which is not high-level waste (HLW), TRU waste, etc.] while the USNRC uses the formal classification of LLW found in 10CFR Part 61. The second provision of the FFCA of relevance to DOE MLLW disposal programs is the requirement to develop and submit site treatment plans (STPs) for mixed waste at each facility at which the DOE stores or generates these wastes. These plans identify how the DOE will provide waste treatment for all MLLW waste streams and must include schedules for bringing new facilities into operation. The DOE identified 35 sites requiring STPs and submitted Draft STPs for nearly all of these sites in October 1995. Since its passage, the FFCA has provided a strong incentive for the DOE to work with the states to develop management and disposal strategies for mixed HLW, LLW, and TRU waste. A number of initiatives were begun that have significantly improved the relationship between these two parties with respect to waste management.

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--> and Recovery Act (RCRA), enacted in 19762 RCRA has been amended several times, with the most significant amendments passed in 1984 as the Hazardous and Solid Waste Amendments. RCRA provides for the cradle-to-grave control of hazardous wastes by imposing management requirements on generators and transporters of hazardous waste and on owners and operators of treatment, storage, and disposal facilities. Regulations pertaining to RCRA waste disposal facilities (landfills) include such details as liner and cover designs. Figure 2 illustrates a RCRA landfill. The RCRA hazardous waste regulations are found in Title 40 of the Code of Federal Regulations (EPA, 1996). Parts 260 to 265 describe hazardous waste management, provide EPA's lists of hazardous wastes, and set standards that must be met by hazardous waste generators and managers. EPA's land disposal restrictions are given in 40CFR268 and its permit programs in 40CFR270. Hazardous wastes are defined in 40CFR261. Waste materials are classified as hazardous in two ways. The first way is if constituents in the waste appear on comprehensive lists including more than 700 materials, representing non-specific wastes (such as electroplating wastes or spent solvent wastes),3 unique wastes from specific industries, and commercial chemical products including residues and spills. These are known as "listed wastes." The second way is for the waste material to exhibit hazardous characteristics of ignitability, corrosivity, reactivity,4 or toxicity; these wastes are referred to as "characteristic wastes." The toxicity characteristic is defined by a list of 40 materials, comprised of seven metals (including lead, chromium, cadmium, and mercury)5, and 33 pesticides and solvents (including chlorinated solvents commonly found in industrial wastes). A waste material may be declared 2   A history of EPA's regulation of mixed waste beginning in 1976 can be found on the EPA Mixed Waste Team internet home page: http//www.epa. gov/radiation/mixed/waste/. 3   More than 80% of the EM mixed waste inventory is listed as hazardous because of these materials. 4   Reactive materials may pose a fire or explosion hazard in the course of handling or disposal. 5   More than 50% of the EM mixed waste inventory is listed as hazardous because it contains these metals.

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--> Figure 2 Illustration of a RCRA Landfill. SOURCE: EPA, 1999b hazardous based upon knowledge of process chemistry or it may be tested. A common test for the toxicity characteristic as well as for many listed waste constituents is the Toxicity Characteristic Leaching Procedure (TCLP), which involves the extraction of the solid waste material by a weak acetic acid solution. The presence of characteristic wastes or listed wastes in the extract in excess of established concentration limits confirms the solid waste to be a hazardous waste. Untreated EM wastes will often include a combination of both listed and characteristic wastes.

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--> A waste that has been determined to be hazardous is subject to the provisions of the Land Disposal Restrictions (LDRs) as described below.6 Characteristic waste may be treated to exit the hazardous waste management system. Listed wastes may be delisted, but may still be subject to the LDRs.7 A more thorough discussion of the TCLP in the context of waste form characterization is provided in Chapter 5. LDRs in 40CFR268 apply to all hazardous wastes, including mixed wastes. LDRs either identify the maximum concentrations of hazardous constituents in waste that may be disposed of in a permitted hazardous waste landfill or prescribe ways that the waste may be treated to allow disposal in a permitted hazardous waste landfill. Prescriptive treatment methods are referred to as Best Demonstrated Available Technology (BDAT).8 BDAT applies to three categories of radioactively contaminated wastes: (1) lead solids; (2) elemental mercury; and (3) hydraulic oils contaminated with mercury (Sullivan, 1997). In addition to BDAT treatment for low-level mixed waste, other BDAT treatment standards for hazardous waste will apply to mixed waste where specific waste constituents are identified. For most waste constituents of direct concern to EM, BDAT has not been identified, but treating the waste to meet the Universal Treatment Standards (UTS) will allow disposal in a landfill. The UTS specify the maximum allowable concentration of waste constituents in the treated waste, either by direct analysis or application of the TCLP procedure, but do not specify the treatment process. In addition, EPA recognizes that some mixed wastes may not be treatable by either by 6   Currently EPA is preparing a "Hazardous Waste Identification Rule" (HWIR) to amend certain portions of the RCRA regulations. The purpose of the HWIR is to exempt from hazardous waste regulations those materials currently designated as hazardous waste if they contain hazardous constituents only at concentrations that pose very low risk to humans and the environment. These wastes could then be disposed of in non-hazardous (Subtitle D) landfills or other disposal units. 7   Regulations in 40CFR260.22 provide methods for "delisting" or removing specific wastes or treated wastes at a given facility from provisions of the hazardous waste program. In general, the petitioner must show through comprehensive testing and analysis that the specific material does not meet the criteria that caused it to be listed by the (EPA) Administrator. 8   40CFR268.42

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--> BDAT or to the UTS. In such situations, EPA will allow petitions to be submitted to request a variance. The Toxic Substances Control Act (TSCA) of 1976 (as amended) addresses materials in wide use that pose an extraordinary hazard to persons who may come in contact with them. Examples include polychlorinated biphenyls (PCBs) and asbestos. TSCA gives EPA authority to regulate the manufacture, use, distribution, and disposal of these hazardous materials. In addition, TSCA includes provisions for handling and cleaning up wastes containing PCBs. These provisions apply even if the wastes were generated before the effective date of TSCA. As discussed in Chapter 2, a small but significant amount of EM's mixed waste inventory is suspected to be contaminated with PCBs. To put EPA's hazardous waste regulatory approach in perspective, one must recognize that its regulations apply to over 500,000 companies and individuals throughout the United States (Case, 1991). Thus, there is a strong justification for the regulations to be applicable universally and to contain straightforward numerical criteria that are relatively easy to understand and enforce. The EPA approach to assuring safety includes a definition of hazardous waste, specifies treatment standards that must be met prior to land disposal, and specifies standards for construction and operation of hazardous waste disposal sites. The specificity of the regulations does not require interpretation by DOE; only compliance is required. In summary, the EPA regulations that apply to EM's program for managing its mixed wastes require the following: Systems constructed to treat mixed wastes must be permitted by EPA or the host state (40CFR264). Inventory reporting and other requirements of TSCA must be followed. Each hazardous waste storage or disposal facility must be permitted and approved (40CFR264 and 40CFR270). MLLW disposal must meet EPA's hazardous waste landfill regulations, including LDRs (40CFR268). Mixed TRU wastes are subject to EPA regulations appropriate to high-level and transuranic wastes. These require

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--> deep geological disposal and performance assessment over a 10,000-year time period.9 U.S. Nuclear Regulatory Commission The USNRC operates under the authority of the Atomic Energy Act of 1954 (AEA) and its subsequent amendments. USNRC regulations that affect management of DOE mixed wastes include the following: 10CFR61 Low-level Waste Disposal Regulations;10 and 10CFR20 Radiation Protection Standards. The waste disposal regulations require that releases from the disposal facility meet the radiation protection standards. The USNRC closely regulates the waste form stability and radioactive characteristics of low-level waste materials acceptable for near-surface land disposal through a combination of prescriptive and performance-based requirements (10CFR61.55–56). According to 10CFR61, a near-surface disposal facility is one in which radioactive waste is disposed in or within the upper 30 meters of the land's surface. Institutional control of access is required for 100 years (10CFR61.7), and within 500 years, wastes must decay to a sufficiently low-level that remaining radioactivity will not pose unacceptable hazards to an intruder or the general public. To meet this latter requirement, further prescriptive regulations define three classes of waste that are deemed suitable for near-surface disposal. Classification as Class A (the least restrictive), Class B, or Class C depends on which radionuclides are present and their concentrations. The radioactive half-life is the primary discriminator (Table 2). If any long-lived nuclides are present in the waste in concentrations greater than given in Table 2, the waste is not suitable for near-surface disposal.11 Mixed transuranic waste (MTRU) is thus 9   40CFR191 and 40CFR194 10   Commercial disposal facilities must be licensed by the USNRC. Commercial facilities, such as Envirocare in Utah, are expected to be the final destination for about 30% of DOE's MLLW (DOE, 1997). 11   Mining industry waste is excluded from this requirement.

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--> TABLE 2 Allowable Concentrations of Long-Lived Radionuclides for Near-Surface Disposal Radionuclide Concentration, curies per m3 (Ci/m3) 14C 8 14C in activated metal 80 59Ni in activated metal 220 94Nb in activated metal 0.2 99Tc 3 129I 0.08   Concentration, nanocuries per gram (n Ci/g) Alpha emitting transuranic nuclides with half-life greater than 5 years 100 241Pu 3,500 242Cm 20,000   SOURCE: 10CFR61.55 TABLE 3 Allowable Concentrations of Short-Lived Radionuclides for Near-Surface Disposal Radionuclide Class A Waste (Ci/ m3) Class B Waste (Ci/ m3) Class C Waste (Ci/ m3) Total of all nuclides with less that 5-year half-life 700 Note 1 Note 1 3H 40 Note 1 Note 1 60Co 700 Note 1 Note 1 63Ni 3.5 70 700 63Ni in activated metal 35 700 700 90Sr 0.04 150 7000 137Cs 1 44 4600 SOURCE: 10CRF61.55 Note 1: There are no limits for these radionuclides in Class B or C wastes. Practical considerations such as the effects of external radiation and internal heat generation on transportation, handling, and disposal limit the concentrations for these wastes. These wastes shall be Class B unless the concentrations of other nuclides in Table 2 determine the waste to be Class C independent of these nuclides.

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--> generally excluded from near-surface land disposal by USNRC regulations, and requires deep geological isolation. Disposal of MTRU in the Waste Isolation Pilot Plant (WIPP) repository is described at the end of this chapter. In the absence of long-lived radionuclides, near-surface disposal of substantial concentrations of short-lived nuclides is allowed according to the provisions in Tables 2 and 3.12 The USNRC historically has used performance-based standards in addition to prescriptive requirements. The original USNRC standards were developed for occupational exposure and were based on the probability of one premature death per year among 10,000 exposed individuals (Gershey, et al., 1990). Rather than establish designs for a disposal facility or establish strict numerical standards for each radionuclide, USNRC regulations establish performance objectives (10CFR61, Subpart C) that define regulatory limits (accepted health-based standards) for the radiation exposure that a person in the vicinity of a disposal site may receive. A disposal facility must be able to perform its function of retaining radionuclides well enough to meet these objectives. A technical analysis is required to demonstrate that a specific system can meet the performance objectives. The USNRC has responded to the need for a technical analysis through the development of performance assessment (PA) methodology (USNRC, 1997). PA can be used to demonstrate compliance with USNRC's performance objectives for radiological protection of the general public established under 10CFR61.41. The DOE has also adopted the use of PA methods for determining compliance with its radioactive waste regulations. Because the PA is essential for demonstrating the long-term safety of a disposal system, the methodology is described in Chapter 6 of this report. 12   When waste contains several radionuclides, but none exceeds the limits in Table 2 or 3, the fractions of the limit for each nuclide are summed. If the sum exceeds 1.0, the waste is deemed unsuitable for near-surface disposal. For example, waste with a concentration of 2 curies of 99Tc per cubic meter and 70 nanocuries of transuranic nuclides per gram would have a sum of fractions of 1.36 (i.e., 2/3 + 70/100). It would be prohibited from near-surface disposal. Requirements for wastes containing long-lived nuclides having a sum of fractions greater than 0.1 include structural stability and additional disposal conditions to guard against inadvertent intrusion.

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--> For making a PA, USNRC regulations place emphasis on siting criteria, and, in particular, recognize the importance of ground water flow as a contaminant transport mechanism (10CFR61, Subpart D). USNRC regulations state that "site characteristics should be considered in terms of the indefinite future and evaluated for at least a 500-year time frame" (10CFR61.7). Recent USNRC documents suggest that a 10,000-year horizon may be an appropriate end point for PA studies covering the disposal system for low-level mixed waste (USNRC, 1997). As will be discussed in Chapters 5 and 6, there are no available tests that can reasonably predict the very long-term performance of waste forms. As a result, performance assessments often take little credit for retention of long-lived radionuclides by the waste form. U.S. Department Of Energy In compliance with the FFCA, DOE regulates cleanup and waste disposal at its sites through implementation of internal orders based on its authority under the AEA. These orders include the following: DOE Order 5400, General Environmental Protection (DOE, 1998a); and DOE Order 5820, Radioactive Waste Management. DOE is required to manage its mixed wastes in a manner that assures the health and safety of site operating personnel and the public, and protection of the environment. Waste treatment must minimize the generation of secondary wastes and comply with all applicable federal, state, and local environmental, health, and safety laws and regulations. DOE Order 5400.5 sets radiation exposure standards for the public and on-site personnel. These standards permit a total of 100 millirem per year (mrem/yr) exposure to an individual member of the public. Of this total, only 10 mrem/yr can result from inhalation of airborne particles, and exposure from ingesting radionuclides in drinking water is limited to 4 mrem/yr13 Any disposed radioactive or mixed waste 13   The remainder would come mainly from sources outside the body (i.e., external doses).

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--> must not contribute to the exposure of the public in excess of these amounts. Permissible levels of radioactivity would, therefore, depend on the ability of the disposal system to retain the radionuclides. Additionally, all exposures must be limited to "as low as reasonably achievable" levels. DOE Order 5820.2A deals with radioactive waste management, including high-level waste, TRU waste, and LLW, and contains a number of provisions that meet and extend the regulatory criteria established by the USNRC. The order, promulgated in 1988, requires that the concept of waste minimization, including waste segregation, be applied in process design and operation. The order also requires a PA for all disposal facilities. There are two objectives that must be addressed in PA models (DOE, 1996c). The first objective is to assure that the disposed waste will not cause an exposure (effective dose equivalent) greater than 25 mrem/yr to any member of the public. DOE has interpreted this to include all pathways of possible exposure during the period of 1,000 years following closure of the disposal facility. To increase confidence in the outcome of the modeling, analysis beyond 1,000 years (but not exceeding 10,000 years) may be done (DOE, 1996c). The second applicable performance objective addresses inadvertent intrusion after the institutional control period (100 years), requiring that the effective dose equivalent received by an individual who might inadvertently intrude into the facility not exceed 100 mrem/yr for continuous exposure or 500 mrem for a single acute exposure. PA modeling of this scenario beyond 1,000 years post-closure is not recommended. Waste Acceptance Criteria and Other Requirements In addition to the waste treatment and disposal regulations that were discussed in the previous section, controls may be imposed at waste treatment or disposal sites through the mechanism of WAC. All DOE facilities are required to have WAC for waste received by that facility for treatment or disposal (DOE Order 5820.2A). As indicated by

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--> the name, WAC describe requirements that are placed on received waste in order that it can be accepted at a facility. Wastes delivered to any disposal site are required to meet LDR and any conditions imposed by the WAC or the facility permitting process. The criteria may address shipping requirements; containerization; physical, nuclear, and chemical properties, including gas generation; and waste characterization. Each facility develops specific WAC to ensure that it operates safely and will meet all applicable regulations during operation and after closure. For non-DOE facilities, such criteria may be incorporated in the facility permit or specified separately. In the case of treatment facilities, the WAC do not establish requirements on the waste form for disposal but rather on the waste as received in anticipation of further treatment prior to disposal. WAC are site specific, and may place additional constraints on the selection of waste forms for disposal. Except for the Envirocare of Utah facility, no commercial options are available for the land disposal of DOE mixed waste. At Envirocare, the WAC place low limits on the radioactivity of waste that can be received, thereby restricting the use of this site. Although the DOE sites at Hanford and the Nevada Test Site can dispose of mixed wastes generated on-site, they are not currently available for mixed waste generated at other sites. The WIPP project may accept waste meeting the definition of TRU and MTRU waste, but it may not receive MLLW. Since disposal sites are not available for the majority of MLLW, DOE is faced with having to design treatment systems and subsequent waste forms without knowledge of potential constraints that may be imposed in the future. Waste treatment and temporary storage of the waste forms until a disposal facility is available may be necessary to meet EM's cleanup schedule. However, this expedient is more uncertain and expensive compared with treatment followed immediately by final disposal, and imposes an additional set of regulations applicable to temporary storage facilities. Shipping regulations imposed by DOT may add constraints with regard to packaging of waste material for transport if wastes must be shipped to an off-site location for treatment or disposal. A description of the effect of WAC and transportation requirements on TRU waste forms for the WIPP facility is given in Box 2.

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--> Box 2 The Role of Waste Forms at WIPP: A Special Case for Mixed TRU Waste The Waste Isolation Pilot Plant (WIPP) is an underground facility designed for the disposal of DOE TRU waste. The repository is located in a semi-arid region of southeastern New Mexico. WIPP is constructed in bedded salt at a depth of approximately 658 m (2,160 ft) (see Figure 3). A description of the WIPP facility, the site hydrogeology, the waste characteristics planned for the facility, and the regulatory issues that must be met by the facility was published by the National Research Council's Committee on WIPP (NRC, 1996b). WIPP is expected to be the disposal facility for nearly all of DOE TRU and mixed TRU waste.* The design capacity of WIPP is 168,500 m3 of contact-handled waste and 7,000 m3 of remote-handled waste. The principal radioactive constituents of the waste will be uranium and isotopes of the transuranic elements neptunium, plutonium, and americium with half-lives greater than 20 years and concentrations greater than 100 nCi/g (DOE Order 5820.2A). In 1992, the WIPP Land Withdrawal Act (Public Law 102–579) transferred control of land at the WIPP site from the Department of the Interior to the DOE. A major provision of the Act requires DOE to show that the repository will comply with applicable federal regulations. The principal regulations that WIPP must satisfy are the EPA general regulations for spent fuel and TRU wastes in 40CFR191, specific regulations developed for WIPP in 40CFR194, and RCRA 40CFR Chapter I provisions pertaining to management and disposal of hazardous wastes. WIPP is also subject to DOE regulations in DOE Order 5820.2A. Congress passed amendments to the Land Withdrawal Act (Public Law 104–201) that exempted WIPP from treatment standards and LDR requirements. Thus, wastes do not require any form of stabilization for disposal in the WIPP. All waste will be placed in 55-gallon steel drums or in standard waste boxes, which will be placed in DOT-approved TRUPACT II canisters for transportation to WIPP. The waste will be disposed of in the same drums or waste boxes. Remotely handled TRU waste will be placed in approximately 1 m3 steel canisters. The waste will be placed in mined-out disposal rooms that are approximately 4 m high, 10 m wide and 100 m long. It is anticipated that salt creep will completely close the rooms and compact the waste within 100 years.

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--> Gas generation resulting from the decay of organic matter in the waste is a concern because it might lead to build-up of high pressures in the repository. This could compromise containment of the wastes in the event of a drilling intrusion into the disposal region. Magnesium oxide (MgO) will be emplaced with the waste to limit the effects of gas generation by forming a precipitate with CO2. The National Research Council's Committee on the Waste Isolation Pilot Plant reviewed the status of WIPP and its suitability as a repository for TRU waste (NRC, 1996b). Among other issues, the WIPP committee considered the issue of waste form modification and whether significant benefits could be achieved by additional waste treatment or stabilization. The WIPP committee noted that: Extra costs would be incurred to treat the waste. There would be more risk to treatment plant personnel than if untreated waste were being disposed. A waste treatment system would take significant time to implement. Treatment options would involve more complicated regulatory requirements. This led the WIPP committee to agree with DOE's conclusion that additional waste treatment or stabilization is not desirable in the special case of the WIPP. *   The WIPP received its first shipment of TRU waste on March 26, 1999, as this report was being prepared for publication. To receive mixed TRU waste, the WIPP lacks only a hazardous waste permit, which must be issued by the New Mexico Environment Department.

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--> Figure 3 Location of the Waste Isolation Pilot Plant site. Inset map shows approximate location of map area in the state of New Mexico. SOURCE: Modified slightly from Sewards, et al. (1991, Figure III-1). Comments and Recommendation The state of development of technologies for treating mixed waste and converting it to stable waste forms must be assessed in the context of the regulations that control these wastes. The committee found that the absence of an agreed-upon set of guidelines for acceptance of

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--> waste forms at future disposal facilities and for performance of waste forms in the disposal environment introduces significant uncertainties into EM's technology development programs. The unavailability of existing disposal facilities that have USNRC licenses and EPA or state permits to accept mixed waste places uncertainties on the selection of treatment processes and waste forms. Currently, EM must make assumptions about the acceptability of its intended waste forms at expected disposal sites in order to complete the design of treatment systems. Treatment system modification or additional treatment of the waste may be required if the expected site does not become available, or if the waste form does not meet unanticipated WAC at a new site. Although the regulatory goals of USNRC and EPA are the same, protection of health and the environment, the committee noted that fundamentally different approaches are used by the two agencies to achieve this goal. EPA regulations are applied to a large range of waste streams. Therefore, EPA has adopted prescriptive regulations with options for exception. In contrast, USNRC and DOE regulations apply to a relatively small number of waste streams, allowing individualized licensing and permitting to conform to performance standards. These differences result in apparent inconsistencies between the respective regulations, which make management of mixed waste difficult. The USNRC and DOE require that the waste form, packaging, and emplacement ensure stability and performance predictability. The essential measure of disposal acceptability is the performance assessment that is used to estimate the dispersion of the radioactive species from the disposed waste over a long time scale, and to compare this estimate against some standard of acceptable off-site effects. In addition, the disposal site must be retained in perpetual custody by the state or DOE.14 The EPA regulatory approach is prescriptive: define the hazardous waste by listing or by its hazardous characteristics as measured by the TCLP, set waste form requirements for resistance to leaching, and require that the disposal facility include features such as a cover, a dual liner, and a leachate collection system. The design requirements for the disposal facility and its contents are such that virtually no leaching should occur in the 30-year performance period. 14   Section 11.e(1) in the Atomic Energy Act of 1954.

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--> Some further specific examples of these differences are the following: Disposal facility design. EPA has developed design criteria for hazardous waste disposal facilities that apply regardless of the geologic and climatic setting. USNRC does not identify or recommend any particular design, but instead establishes performance objectives for the entire disposal system. The performance objectives include consideration of site geology and climate. Joint USNRC-EPA guidance for conceptual design of MLLW disposal facilities has been written (EPA, 1987). Disposal facility approval. EPA's permitting procedure for establishing a disposal facility includes site characteristics but not waste characteristics.15 The USNRC requires a performance assessment to demonstrate that a disposal facility will meet its performance objectives. The performance assessment must consider both site and waste characteristics. Waste concentration limits. For near-surface disposal of any waste, EPA sets maximum concentration limits for hazardous materials in the waste (either directly or through application of a BDAT treatment) or requires that the waste form pass the TCLP. The USNRC uses a waste classification system that allows near-surface disposal of waste containing only very low-levels of long-lived radionuclides but relatively high concentrations of short-lived radionuclides. Period of performance. EPA requires a disposal facility to contain all waste constituents during a minimum 30-year monitoring period after closure.16 The USNRC requires preparation of a formal performance assessment to demonstrate that the site will meet quantitative performance objectives. The 15   For facility operation, waste characteristics must be known, for example, to ensure that a given waste will not react with other wastes, that it is compatible with the containment system, and that it has been treated to LDR levels prior to disposal. 16   At the end of the 30-year period, the EPA administrator may extend the post-closure period if deemed necessary for protection of human health and the environment.

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--> USNRC has recommended that the period of performance considered in the PA be at least 1,000 years and may be extended to 10,000 years or more. Waste form performance. Neither the DOE, EPA, nor the USNRC provides guidance for waste form performance in the repository environment. As noted earlier, EPA requires only that waste forms pass the TCLP. Performance assessments required by USNRC and the DOE generally give little credit for waste containment to the waste form. This lends conservatism to the calculations of disposal facility performance as will be discussed in Chapter 6. The committee recommends that because of the lack of available disposal sites for MLLW and the difficulties in establishing new sites, EM should work with EPA and the USNRC to agree on clear guidelines that describe acceptable waste forms for disposal of mixed waste in future, near-surface disposal facilities. This should be done as soon as possible to reduce the risk of EM deploying technologies that are later judged inadequate because of unanticipated regulatory requirements.