3
Regulatory Context for the Disposal of Remote-Handled Transuranic Waste

The Land Withdrawal Act, Public Law 102–579, is the guiding legislation for WIPP (U.S. Congress, 1992). In this Act, Congress established the scope and legal criteria for the facility. The Land Withdrawal Act also assigned EPA regulatory authority over public exposure to radiation from the management and storage of TRU waste at WIPP during the operational period (nominally lasting until 2033) and over radioactivity releases into the environment up to 10,000 years after repository closure. The hazardous non-radioactive component of TRU waste is regulated by the NMED under RCRA (EPA, 1990). The NMED standards for a hazardous waste disposal facility (such as WIPP) seek to minimize releases1 of non-radiological hazardous constituents during the operational phase and for a nominal 30-year period following repository closure.

The two main regulatory documents for WIPP are the EPA Certification and the RCRA Permit. To continue disposal operations, WIPP must show continued compliance with the EPA Certification and the RCRA Permit. One of the conditions contained in the EPA certification is that EPA and NMED must approve site-specific characterization measures and quality assurance programs before generator sites ship waste to WIPP. Therefore, the EPA Certification and RCRA Permit establish waste characterization requirements for all TRU waste (CH or RH) to be emplaced in WIPP.

The requirements for TRU waste characterization used by EPA and NMED originate from the following standards for owners and operators of hazardous waste treatment, storage, and disposal facilities:

“(a)(1) Before an owner treats, stores, or disposes of any hazardous wastes, or nonhazardous wastes if applicable under §264.113(d), he must obtain a detailed chemical and physical analysis of a representative sample of the wastes. At a minimum, the analysis must contain all the information which must be known to treat, store, or dispose of the waste in accordance with this Part and Part 268 of this chapter” (40 CFR 264.13).

EPA indicates in the same document that characterization information can be obtained either by direct measurement or indirectly through AK (see Sidebar 2.1).

1  

With an exemption from Land Disposal Restriction regulations (40 CFR 268), Congress determined that WIPP waste does not need treatment prior to disposal. As a result, the NMED imposed groundwater and air monitoring requirements to ensure that any detectable release remains below specific limits that have been established to protect human health and the environment.



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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report 3 Regulatory Context for the Disposal of Remote-Handled Transuranic Waste The Land Withdrawal Act, Public Law 102–579, is the guiding legislation for WIPP (U.S. Congress, 1992). In this Act, Congress established the scope and legal criteria for the facility. The Land Withdrawal Act also assigned EPA regulatory authority over public exposure to radiation from the management and storage of TRU waste at WIPP during the operational period (nominally lasting until 2033) and over radioactivity releases into the environment up to 10,000 years after repository closure. The hazardous non-radioactive component of TRU waste is regulated by the NMED under RCRA (EPA, 1990). The NMED standards for a hazardous waste disposal facility (such as WIPP) seek to minimize releases1 of non-radiological hazardous constituents during the operational phase and for a nominal 30-year period following repository closure. The two main regulatory documents for WIPP are the EPA Certification and the RCRA Permit. To continue disposal operations, WIPP must show continued compliance with the EPA Certification and the RCRA Permit. One of the conditions contained in the EPA certification is that EPA and NMED must approve site-specific characterization measures and quality assurance programs before generator sites ship waste to WIPP. Therefore, the EPA Certification and RCRA Permit establish waste characterization requirements for all TRU waste (CH or RH) to be emplaced in WIPP. The requirements for TRU waste characterization used by EPA and NMED originate from the following standards for owners and operators of hazardous waste treatment, storage, and disposal facilities: “(a)(1) Before an owner treats, stores, or disposes of any hazardous wastes, or nonhazardous wastes if applicable under §264.113(d), he must obtain a detailed chemical and physical analysis of a representative sample of the wastes. At a minimum, the analysis must contain all the information which must be known to treat, store, or dispose of the waste in accordance with this Part and Part 268 of this chapter” (40 CFR 264.13). EPA indicates in the same document that characterization information can be obtained either by direct measurement or indirectly through AK (see Sidebar 2.1). 1   With an exemption from Land Disposal Restriction regulations (40 CFR 268), Congress determined that WIPP waste does not need treatment prior to disposal. As a result, the NMED imposed groundwater and air monitoring requirements to ensure that any detectable release remains below specific limits that have been established to protect human health and the environment.

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report The regulatory requirements for the characterization of TRU waste in WIPP originate from the Land Withdrawal Act, the EPA Certification, and the RCRA Permit. These requirements are described below. 3.1 Land Withdrawal Act Requirements for Transuranic Waste in WIPP The Land Withdrawal Act establishes the five main legal requirements for TRU waste in WIPP, some of which apply specifically to RH-TRU waste. These requirements are the following: Nature of waste to be disposed of in WIPP: the WIPP can only receive transuranic waste generated by atomic energy defense activities. Total volume of transuranic waste: the WIPP is allowed to contain up to 175,564 cubic meters of transuranic waste. Volume of RH-TRU waste: the WIPP is allowed to contain up to 7,080 cubic meters of RH-TRU waste, which represents about 4 percent of the total volume of TRU waste allowed. Total activity of RH-TRU waste: RH-TRU waste received at WIPP shall not exceed 23 curies per liter maximum activity level (averaged over the volume of the container). The total curies of RH-TRU waste received at WIPP shall not exceed 5.1 million curies.2 Surface dose rate: no TRU waste received at WIPP may have a surface dose rate exceeding 1,000 rems per hour. No more than 5 percent by volume of RH-TRU waste received at WIPP (354 cubic meters) may have surface dose rates exceeding 100 rems per hour. Tolerable uncertainties are not specified in the Land Withdrawal Act for the above limits. Laws seldom specify accuracy or precision of limits; it is generally the duty of the implementer to propose tolerable decision errors, such as accuracy or uncertainty, derived from a tradeoff among relevant parameters, such as risk or costs. 3.2 Characterization Requirements in the EPA Certification In 1998, EPA promulgated the criteria for the certification and recertification of the Waste Isolation Pilot Plant’s compliance with the 40 CFR 191, subparts B and C (40 CFR 194). The EPA declared WIPP to be in compliance with its disposal regulations and granted the facility a certification of compliance. The purpose of the EPA characterization requirements is to ensure that WIPP remains in compliance with the EPA disposal regulations and limits set forth in the Land Withdrawal Act. Compliance is ensured if the waste inventory in WIPP stays within the waste envelope limits specified in WIPP’s performance assessment. The performance assessment is a tool used to evaluate the safety performance of any nuclear waste facility, as explained below. 2   Note that the total activity limits for RH-TRU waste do not distinguish between the activity due to the TRU nuclides and that due to other radionuclides.

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report 3.2.1 WIPP’s Performance Assessment The performance assessment evaluates the ability of a repository to satisfy the release limits (listed in 40 CFR 191, Appendix A) on the release of radionuclides from a repository over a period of 10,000 years. The performance assessment organizes information relevant to long-term repository behavior by assessing the probabilities and consequences of major scenarios by which radionuclides can be released into the environment. Important scenarios include those due to human activities, whether deliberate or unintentional, that might compromise the integrity of the repository. The performance assessment process consists of: compiling features, events, and processes that could affect the disposal system; classifying events and processes to enhance consistency and completeness; screening individual events and processes for likelihood of occurrence and consequences; combining events and processes into specific scenarios; screening scenarios to identify and eliminate those that have little or no effect on the performance assessment; modeling the scenarios; calculating the releases; and comparing the calculated values with the allowable releases. From the quantitative results of its performance assessment, DOE identified the ten radionuclides most important to the long-term performance of WIPP: americium-241, cesium-137, plutonium-238, plutonium-239, plutonium-240, plutonium-242, strontium-90, uranium-233, uranium-234, and uranium-238. Of these ten, strontium-90, uranium-233, and cesium-137 are important to RH- but not CH-TRU waste streams (due to the gamma and beta emissions). A sensitivity analysis of the performance assessment also identified the non-radiological waste parameters most important to the performance of the repository (Helton et al., 1998). These parameters are the following: Amount of free water: The EPA Certification requirements include a limit on the total amount of water or brine present in the waste. This parameter is important because water is the only means to release radionuclides in the environment and because it controls several other factors, such as corrosion and gas generation.3 The total limit for free water in WIPP is 1 percent by volume in the entire TRU waste inventory (175,564 cubic meters), which corresponds to 1,756 cubic meters. This limit derives from a transportation requirement forbidding shipment of hazardous waste containing more than 1 percent of free liquids by volume.4 DOE used this requirement as one of the initial assumptions in the performance assessment calculation, which was part of the compliance certification application. This free water 3   The main gases potentially generated in WIPP in the presence of brine are carbon dioxide, methane, and hydrogen. These gases are generated by microbial waste degradation inside WIPP. In addition, hydrogen can also be produced by radiolysis or by corrosion of metal containers. An increase in gas pressure inside the repository could affect room closure rates, fracture development, brine inflow, and the possibility of waste entrainment in gas during a drilling event (called spalling). 4   The committee does not review transportation requirements in this report.

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report requirement is now integrated as part of the EPA Certification to ensure compliance with release limits. Amount of ferrous metals: The EPA Certification requirements include a minimum amount of ferrous metals (20 million kilograms) to ensure a reducing environment inside the WIPP repository. A reducing environment maintains radionuclides in a low oxidation state, which usually corresponds to a minimum solubility. Therefore, waste characterization must ensure that the amount of corrodible metals in the waste is above the minimum. Amount of non-ferrous metals: The EPA Certification requirements include a minimum amount (2,000 kilograms) of non-ferrous metals in WIPP. Non-ferrous metals form complexes with organic ligands present in waste (such as EDTA or citric acid5). This prevents actinides from binding with these organic ligands and becoming mobile. Therefore, waste characterization must ensure that the amount of non-ferrous metals in the waste is above the minimum. Amount of biodegradable cellulosics, plastic, and rubber: The EPA Certification requirements include a maximum amount (20 million kilograms) of cellulosics, plastic, and rubber in the waste to take into account the potential for gas generation from the decomposition of these organic materials. Therefore, waste characterization must ensure that the amount of cellulosics, plastic, and rubber in the waste is below the maximum. Tolerable uncertainties have not been specified in the compliance certification application for the above limits. In its final certification decision, EPA writes: “[T]he EPA confirmed the results of the performance assessment using the same upper and lower limiting values in the performance assessment verification test (“PAVT”). Those upper and lower limiting values apply to contact-handled, remote-handled, and to-be-generated waste from numerous generator sites. Thus, in today’s action, EPA certifies that the WIPP will comply with the 40 CFR Part 191 containment requirements to the extent that emplaced waste falls within the waste envelope limits that were shown by the performance assessment, and confirmed by the PAVT, to be compliant with the 40 CFR Part 191 standards” (40 CFR 194). In summary, the waste characterization requirements appearing in the EPA Certification are aimed to determine: activity and radiological inventory of the waste; surface dose rate; amount of metals (ferrous and non-ferrous); absence of free water; and amount of cellulosics, plastic, and rubber. Chapter 4 describes the approach DOE proposes to determine these 5 characterization parameters in RH-TRU waste. 5   EDTA (ethylenediaminetetraacetic acid) and citric acid are common cleaning agents.

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report 3.3 Characterization Requirements in the RCRA Permit The purpose of the NMED characterization requirements is to ensure that the non-radiological hazardous characteristics of the waste emplaced in WIPP are compatible with the RCRA requirements as codified in Part 20 of the New Mexico Administrative Code. The cornerstone of any RCRA permit is the waste analysis plan, which allows generators and disposal facilities to identify, treat, store, and properly dispose of all hazardous wastes. Waste analysis involves identifying or verifying the chemical and physical characteristics of a waste by performing a detailed chemical and physical analysis of a representative sample of the waste or, in certain cases, by applying AK (EPA, 1994). The characterization plan in the RCRA Permit is aimed at minimizing the possibility of a fire, explosion, or any unplanned sudden or non-sudden release of TRU mixed waste or mixed waste constituents to air, soil, groundwater, or surface water which could threaten human health or the environment (see NMED, 1999a; Module II General Facility Conditions; page II–1). Currently, the waste characterization requirements in the RCRA Permit are aimed at determining the following information: physical form of waste (homogeneous solids, soil or gravel, debris); and exclusion from waste of the following prohibited items6: Liquid waste. Non-radionuclide pyrophorics (addressed by the hazardous waste codes7). Hazardous wastes that do not contain TRU waste. Incompatible chemicals (addressed by the hazardous waste codes). Polychlorinated biphenyls greater than or equal to a concentration of 50 ppm. Explosives (addressed by the hazardous waste codes) and compressed gases. Ignitable, corrosive, and reactive wastes (addressed by the hazardous waste codes). Remote-handled transuranic mixed waste. Prohibited items listed in the RCRA Permit are items that are incompatible (e.g., ignitable, reactive) or inappropriate for the WIPP facility. If combined, incompatible wastes are capable of spontaneous combustion, toxic gas generation, or explosions (EPA, 1994). The selection of waste parameters must include measures to ensure that the waste is appropriate for WIPP’s scope and that inappropriate waste is identified and excluded prior to shipment. The current RCRA Permit excludes RH-TRU mixed waste because: “The Applicant [DOE] failed to submit an approvable waste analysis plan describing the procedures for obtaining a detailed chemical and physical analysis of RH [mixed] waste destined for disposal at WIPP. Moreover, there 6   Additional prohibited items for WIPP are waste containers that do not have volatile organic compound concentrations reported for the headspace, waste containers that have not undergone radiographic or visual examination, and waste containers that do not have a certified waste stream profile form (see the glossary). 7   The definition of hazardous waste codes can be found in the glossary, Appendix I.

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report are substantial questions regarding the applicability of CH waste characterization techniques and the Applicants’ capability to characterize RH [mixed] waste” (NMED, 1999b). To remove the RH-TRU waste prohibition from the RCRA Permit, NMED recommends that DOE build its proposed RH-TRU waste characterization plan upon the requirements in the existing permit and provide justification for any difference between the RH-TRU and the existing CH-TRU characterization plan (Zappe, 2001). 3.4 History of Characterization Requirements at WIPP When DOE first applied for the EPA certification of WIPP, it proposed the same characterization plan for RH-TRU and CH-TRU waste (DOE-CAO, 1996a). DOE, EPA, and NMED negotiated the characterization requirements for TRU waste during nearly two decades prior to the certification of WIPP. Records of the negotiation process show that DOE proposed to the regulators some waste characterization requirements that lacked a technical, safety, or legal basis (see Sidebar 3.1). These requirements eventually became part of the EPA Certification and RCRA Permit and are now addressed in the CH-TRU waste characterization plan. Eventually, EPA and NMED declared that DOE did not provide an adequate waste characterization method for RH-TRU waste and prohibited this waste from being shipped to WIPP. Both agencies also stated that DOE did not adequately describe its full RH-TRU waste inventory. DOE is now submitting a new characterization plan for RH-TRU waste to address EPA and NMED characterization requirements. While the regulatory requirements to be addressed are the same for CH- and RH-TRU waste, DOE proposes a different approach to characterize RH-TRU waste than that used for CH-TRU waste, as described in the following chapter. SIDEBAR 3.1 Findings of the Previous National Research Council’s Committee on the Waste Isolation Pilot Plant A previous National Research Council committee on the Waste Isolation Pilot Plant (WIPP) found that some of the elements in the characterization plan for contact-handled transuranic (CH-TRU) waste are based on terms negotiated in the Resource Conservation and Recovery Act (RCRA) Permit rather than being performance-based characterization requirements (NRC, 2001a; Appendix A1). These requirements concern the sampling and analysis of homogeneous waste, headspace gas sampling and analysis, and visual examination procedures. For instance, the Department of Energy (DOE) proposed to conduct homogeneous waste and headspace gas sampling and analyses on the totality of CH-TRU waste containers to confirm acceptable knowledge (AK) information. Moreover, there appears to be no requirement in the law for the verification of radiography results by visual examination. These requirements were proposed by DOE during the development of the characterization plan and “have no basis in law, the safe conduct of operations to emplace waste in WIPP, or long-term performance requirements” (NRC, 2001 a; page 77). Therefore, the 1998 Committee recommended that DOE “eliminate self-imposed waste characterization requirements” from the CH-TRU waste

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Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report characterization plan (NRC, 2001 a; page 78). DOE agreed with that committee on the fact that some waste characterization procedures are indeed not prescribed by safety or legal requirements and were introduced to facilitate the WIPP certification process (Kehrman, 2002; DOE-CAO, 1999a). A DOE review of the CH-TRU waste characterization procedures revealed that DOE developed self-imposed waste restrictions in the waste acceptance criteria and in the requirements for waste generating sites presented in the quality assurance program plan. The definitions of waste acceptance criteria (DOE-CAO, 1996b) and quality assurance program plan (DOE-CAO, 1998) can be found in the glossary, Appendix I.