5
Assessment of the Proposed Characterization Plan

This chapter provides the committee’s assessment of DOE’s proposed plan for the characterization of RH-TRU waste. On June 28, 2002 DOE submitted the characterization plan to EPA and NMED. The committee did not review the plan as submitted; therefore, findings and recommendations in this chapter apply only to the March 2002 draft.1

According to the statement of task, findings and recommendations are organized as follows:

  1. context of RH-TRU waste characterization;

  2. characterization plan’s technical soundness;

  3. protection of worker safety and health; and

  4. compliance with regulatory requirements.

This assessment is based on technical considerations and on the criteria listed in the statement of task (Sidebar P.1).

5.1 Context of Remote-Handled Transuranic Waste Characterization

Below are some general findings about the DOE’s RH-TRU waste inventories. According to the information gathered, the RH-TRU waste volume estimated for shipment to WIPP will be about 3,800 cubic meters or 2 percent of the total TRU waste volume allowed in the repository. Even if the information presented in DOE inventories were not accurate, the RH-TRU waste emplaced in WIPP cannot exceed the limits for RH-TRU waste established in the Land Withdrawal Act: 7,080 cubic meters (about 4 percent of the total allowed TRU volume) and 5.1 million curies.

While RH-TRU waste volume represents a small fraction of the allowed TRU waste in WIPP, it accounts for 14 percent of the total curie activity in DOE’s TRU inventory. However, the number of TRU curies in the RH-TRU waste inventory is 2 orders of magnitude lower than that in the CH-TRU waste inventory expected in WIPP (see Table 2.3 in Chapter 2). Also, most of the total (CH plus RH) long-term (i.e., TRU) activity expected in WIPP comes from CH-TRU waste, with only a 0.5 percent contribution from RH-TRU waste.

According to the performance assessment calculations by Sandia National Laboratories, the inventory of RH-TRU waste expected in WIPP will have a negligible

1  

The committee also reviewed a previous draft (July 2001), which was the object of its interim report (see excerpt in Appendix C).



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report 5 Assessment of the Proposed Characterization Plan This chapter provides the committee’s assessment of DOE’s proposed plan for the characterization of RH-TRU waste. On June 28, 2002 DOE submitted the characterization plan to EPA and NMED. The committee did not review the plan as submitted; therefore, findings and recommendations in this chapter apply only to the March 2002 draft.1 According to the statement of task, findings and recommendations are organized as follows: context of RH-TRU waste characterization; characterization plan’s technical soundness; protection of worker safety and health; and compliance with regulatory requirements. This assessment is based on technical considerations and on the criteria listed in the statement of task (Sidebar P.1). 5.1 Context of Remote-Handled Transuranic Waste Characterization Below are some general findings about the DOE’s RH-TRU waste inventories. According to the information gathered, the RH-TRU waste volume estimated for shipment to WIPP will be about 3,800 cubic meters or 2 percent of the total TRU waste volume allowed in the repository. Even if the information presented in DOE inventories were not accurate, the RH-TRU waste emplaced in WIPP cannot exceed the limits for RH-TRU waste established in the Land Withdrawal Act: 7,080 cubic meters (about 4 percent of the total allowed TRU volume) and 5.1 million curies. While RH-TRU waste volume represents a small fraction of the allowed TRU waste in WIPP, it accounts for 14 percent of the total curie activity in DOE’s TRU inventory. However, the number of TRU curies in the RH-TRU waste inventory is 2 orders of magnitude lower than that in the CH-TRU waste inventory expected in WIPP (see Table 2.3 in Chapter 2). Also, most of the total (CH plus RH) long-term (i.e., TRU) activity expected in WIPP comes from CH-TRU waste, with only a 0.5 percent contribution from RH-TRU waste. According to the performance assessment calculations by Sandia National Laboratories, the inventory of RH-TRU waste expected in WIPP will have a negligible 1   The committee also reviewed a previous draft (July 2001), which was the object of its interim report (see excerpt in Appendix C).

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report impact on the repository’s compliance with EPA radiological regulatory standards, compared to CH-TRU waste. The committee acknowledges that there are uncertainties in DOE’s volume and radioactivity inventories of RH-TRU waste. Also, the committee did not assess the validity of the Sandia impact analyses. However, the committee notes that these performance assessment calculations were performed using a peer-reviewed and EPA-approved performance assessment tool, which was the basis for WIPP certification. The committee recognizes that there may be uncertainties associated with the results of these impact analyses and that there may be scenarios that require a new set of performance assessment calculations.2 In response to the committee’s question on uncertainties, Sandia National Laboratories reported that: “Uncertainties in Performance Assessment are dominated by those associated with geologic processes, chemical interactions of the waste, and possible human activities in the future. For example, the intrinsic permeability of the proximal host rock can vary over seven orders of magnitude; uncertainties with respect to microbial degradation of organic materials affect several key intermediate variables, such as long-term repository pressure and saturation; assumptions regarding human activities introduce the most notable impacts on repository performance. With these uncertainties in mind, it can be stated that any additional uncertainty associated with waste components within the currently estimated RH-TRU inventory are not significant to long-term repository performance” (Knowles, 2002). These considerations, as well as the findings and recommendations in this section, set the context for RH-TRU waste characterization. This context is different than that of CH-TRU waste characterization because of the differences in volumes and in isotopic composition, as explained in Chapter 2. Finding 1 A: According to DOE inventories, 95 percent of the RH-TRU waste to be disposed of in WIPP has yet to be generated or needs to be processed, packaged, or repackaged. This waste will be characterized (through visual examination and physical and chemical analyses) at the time of packaging. Recommendation: DOE should emphasize the argument that the characterization information collected for most of RH-TRU waste does not need confirmatory measurements because the repackaging or generation of waste will be carried out under a certified quality assurance program. Rationale: According to the information provided by DOE, over 95 percent of the RH-TRU waste inventory (to be generated, to be packaged or repackaged waste in Figure 2.2) will be characterized using visual examination3 and physical and chemical methods. This leaves a small fraction of RH-TRU waste with more limited historical, analytical, radioassay, and visual examination information or which was not 2   An unexpected brine saturation of the repository in less than 300 years, a change in the scope of the WIPP facility, or a change in the configuration of underground disposal are examples of scenarios for which a new set of performance assessment calculations for both CH- and RH-TRU waste would be warranted. 3   The committee notes that visual examination only provides an image of the content of waste containers. It does not provide any information on the isotopic composition of waste.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report characterized under a certified quality assurance program; in this case, AK may require confirmation. Therefore, for over 95 percent of RH-TRU waste, confirmatory measurements may not be necessary as long as this waste is generated or repackaged using a certified quality assurance program plan. If the volume of RH-TRU waste represents between 2 and 4 percent of the total inventory of TRU waste (176,000 cubic meters), and the information collected for over 95 percent of RH-TRU waste does not need confirmation, then only between 0.1 and 0.2 percent of the total TRU inventory needs confirmatory activities for AK. This is an important observation and it could have a substantial impact on characterization programs proposed for RH-TRU waste. Finding 1B: For 95 percent of the RH-TRU waste inventory, AK refers to newly generated information acquired during waste generation and packaging. Recommendation: DOE should utilize a different term than “AK” for this newly generated information. Rationale: This newly generated information does not include only historical information on the waste. It can include, for instance, analytical data, radioassay data, and visual examination records obtained during waste generation or repackaging. DOE considers this newly generated information, which may not require confirmation, as AK. The committee believes that this is a potentially confusing terminology because AK is usually associated with historical information, which requires some confirmation (see also Sidebar 2.1). The committee acknowledges that visual examination during RH-TRU waste generation or repackaging does not provide information on the radiological content or on the presence of corrosive, reactive, or chemically hazardous waste. However, visual examination is not the only characterization method proposed for newly generated or repackaged waste (see description of the “characterization at the time of packaging” method in Chapter 4, Section 4.4). 5.2 Characterization Plan’s Technical Soundness DOE’s stated objective is to propose a performance-based characterization plan for RH-TRU waste. The committee interprets “performance-based characterization plan” as a plan ensuring repository integrity, protection of the environment, and health and safety of the public and workers while keeping in consideration tradeoffs between greater characterization accuracy and worker risks (see Chapter 4). This section addresses the characterization activities that DOE proposes to implement the data quality objectives listed in Tables 4.1 and 4.2. Finding 2A: The committee found that several characterization activities are based on non-technical considerations. Therefore, this characterization plan is not completely performance based. The committee questions the technical basis of some of the characterization activities proposed by DOE with respect to its stated goal of adopting a performance-based approach. Recommendation: The committee acknowledges that DOE must consider many non-technical factors in composing its characterization plan. However, DOE should propose only characterization activities that have a technical, health and safety, or regulatory basis.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report Rationale: DOE itself recognizes that the characterization plan is based on various considerations other than science and technology. In its response to the findings in the committee’s interim report, DOE stated: “Nearly all resulting characterization objectives are unrelated to repository performance or to safety/technical considerations” (see Appendix D). and, during a recent conference on waste management, DOE explains: “Based on the results of repository modeling…the DOE believes there are no specific RH TRU waste parameters that need to be measured with precision in order to assure repository integrity and assure protection of human health and the environment. This does not mean that no characterization of RH TRU waste is necessary. To the contrary, in order to meet the requirements of the facility design and the facility waste acceptance criteria, specific needs for waste analysis have been identified” (Gist, et al., 2002; pages 2–3). The facility design and the waste acceptance criteria address the requirements in the EPA Certification and RCRA Permit. Regulatory drivers are listed in Chapter 3 and other non-technical considerations at the beginning of Chapter 4. Most of the characterization activities proposed by DOE do not have a technical basis but arise from considerations aimed at maintaining an effective working relationship among DOE, EPA, and NMED. The committee acknowledges that maintaining an effective working relationship among DOE and WIPP’s regulators is important; however, DOE should propose only characterization activities that correspond to technical, health and safety, or regulatory objectives. Concerning the technical basis of some of the characterization activities in Documents 1 and 2, the Sandia impact analyses show that radioisotope, free liquids, cellulosics, plastics, rubber, and ferrous metal content in the RH-TRU waste inventory do not have an impact on repository performance (see Chapter 4). In spite of these impact analyses, Documents 1 and 2 still propose characterization activities to determine the above parameters in RH-TRU waste. The committee provides below examples of characterization activities that do not appear to have a technical basis in the context of RH-TRU waste characterization. Example #1: DOE justifies the characterization requirement concerning free water or liquid content for both EPA and NMED as a transportation-related requirement or as a requirement present in the WIPP Safety Analysis Report.5 DOE provides the rationale for this characterization requirement as follows: “[EPA Characterization Objectives] Account for Free Water, is a regulatory expectation that the RH-TRU Team believes is prudent to meet even though no amount of free water in the RH-TRU waste will impact repository performance. Note that Appendix WCL.5 [of the compliance certification application] states that, ‘Consequently, there is no need to monitor water in the waste for 4   An unexpected brine saturation of the repository in less than 300 years, a change in the scope of the WIPP facility, or a change in the configuration of underground disposal are examples of scenarios for which a new set of performance assessment calculations for both CH and RH-TRU waste would be warranted. 5   For a definition of Safety Analysis Report see the glossary, Appendix I.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report compliance with 40 CFR § 194.24(c)’ The RH-TRU Team recommends that free water in RH-TRU waste be accounted for by some means. [NMED Characterization Objectives] Limit residual liquids to [less than] 1 [percent] volume of RH canister (or drum for 160B), is related to a regulatory requirement to provide secondary containment at the WIPP for potential spills. An analysis justifying the 1 [percent] for CH-TRU waste at the WIPP is part of the HWFP [Hazardous Waste Facility Permit] record, however a similar analysis has not been done for RH-TRU waste. The RH-TRU Team believes it is prudent to include this limit as an RH-TRU waste requirement also” (see Appendix D). DOE acknowledges that the free water/liquid requirement is an operational concern that does not affect the long-term performance of WIPP. Given the results of the Sandia impact analyses, the committee questions the technical basis of this characterization activity. Example #2: One of the data quality objectives listed in Document 1 is the determination of TRU activity (expressed as plutonium-239 content) of RH-TRU waste to comply with the EPA radionuclide release limits. The Sandia impact analyses showed that, even if the entire RH-TRU waste radionuclide inventory were composed of plutonium-239, WIPP would still be in compliance with 40 CFR 191 because of the small volume of RH-TRU waste to be emplaced in WIPP. Therefore, the actual measurement of TRU activity does not have a technical basis for RH-TRU waste. The determination of TRU activity could be addressed by assigning a conservative boundary value of plutonium-239 representing the total RH-TRU waste inventory. Example #3: In the EPA compliance certification application, DOE established limits for ferrous metal content of waste to be emplaced in WIPP. The rationale is the following: “Ferrous and ferrous-alloy metals (and their corroded products) provide the reactants that reduce radionuclides to lower and less-soluble oxidation states. As discussed in Appendix WCA [Waste Characterization Analysis in the compliance certification application], the anticipated quantity of these metals to be emplaced in WIPP is two to three orders of magnitude in excess of the quantity required to assure reducing conditions. The waste containers supply more than enough iron to provide adequate reductant. Therefore, no upper or lower limit need be established for the quantity of ferrous and ferrous-alloy metals that may be emplaced, beyond the present projection of containers” (DOE, 1996a; Appendix WCL.2). According to the information gathered, the minimum amount of ferrous metals will be satisfied by CH-TRU waste containers. The committee was unable to determine the reason for including the implementation of this characterization objective in the RH-TRU waste characterization plan, even though the method (counting containers) is a simple practice performed during waste packaging. Example #4: The Sandia impact analyses showed that, even if the entire RH-TRU waste inventory were composed of cellulosics, plastics, and rubber, it would only have a negligible impact on the repository performance because of the small volume of RH-TRU waste emplaced. Yet, DOE proposes the implementation of this characterization objective in Document 1. Although this objective is not performance based in the case of RH-TRU waste, the committee acknowledges that DOE does not propose to actually measure cellulosics, plastics, and rubber in the waste but uses a conservative estimate described in Table 4.1.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report Example #5: The determination of prohibited items (see Section 3.3, Chapter 3) listed in the RCRA Permit may not be appropriate for RH-TRU waste when the risks associated with hazardous chemical waste are balanced against radiological risks and costs associated with characterization. According to the information gathered, the prohibited items’ determination represents one of the major difficulties in the characterization of RH-TRU waste. In DOE’s characterization plan, there is no analysis of the health and safety implications of the prohibited items in RH-TRU waste. It is important to analyze these yet-undefined safety implications and balance them against potential radiological risks to workers and associated costs of identifying prohibited items in RH-TRU waste. Such an analysis would be helpful to DOE in comparing workers risks and the associated characterization costs. The results of the analysis could support and strengthen DOE’s RH-TRU waste characterization activities with respect to prohibited items. DOE’s proposed characterization plan was significantly modified between July 2001 and March 2002 concerning the determination of prohibited items in RH-TRU waste. In the latter draft, DOE proposes to determine the absence of only free liquids and polychlorinated biphenyls (within their limits). The remaining prohibited items listed in the RCRA Permit (ignitable, corrosive, reactive, pyrophoric and incompatible waste, explosives, and compressed gases) are determined using the EPA hazardous waste codes. This determination is accomplished using AK on a waste stream basis. This change drives the prohibited items determination (except for residual liquids and polychlorinated biphenyls) from a container-by-container basis to a waste stream basis where hazardous waste code assignment decisions are typically made. The committee supports this change since it streamlines characterization operations but still addresses the prohibited items objective in the RCRA Permit. The committee could not determine the technical basis for including the determination of polychlorinated biphenyls (over 50 ppm) in the context of RH-TRU waste. DOE provided the following rationale: “Polychlorinated biphenyls are subject to EPA regulation under TSCA [Toxic Substances Control Act] and are regulated regardless of whether or not they are included in a RCRA permit as a prohibition” (see Appendix D). In the case of a change in the polychlorinated biphenyl disposal regulations,6 DOE must submit a request for a change in the RCRA Permit to remove the 50 ppm provision. This would not be necessary if this provision were not explicitly mentioned in the RCRA permit. Example #6: The March 2002 draft indicates that, if AK data are not sufficient, then 10 percent of waste should be characterized with alternative methods (see Tables 4.1 and 4.2). The committee could not determine the technical basis for choosing 10 percent of waste as a representative sample of the waste stream. In general, the size of a representative sample is the result of an analysis involving statistical considerations as 6   The new polychlorinated biphenyls disposal regulations (Disposal of Polychlorinated Biphenyls (PCBs), 63 Federal Register 35384, effective August 28, 1998) allows polychlorinated biphenyl-contaminated radioactive waste to be disposed of without a TSCA permit provided the waste meets the requirements for disposal in a non-hazardous waste landfill or a hazardous waste landfill. This recent regulatory change would allow disposal at WIPP of some polychlorinated biphenyls-contaminated wastes where the polychlorinated biphenyls component exceeds 50 ppm. On March 22, 2002 DOE submitted an “Initial Report” to EPA Region VI requesting authorization to dispose of polychlorinated biphenyls in WIPP.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report well as waste stream profile considerations. No such analysis or any other justification was provided in the March 2002 draft. A 10 percent waste sample size may be too big or too small, depending on the waste stream, on the quality of AK available, and on the tolerable decision error rates (see Finding 2C). Finding 2B: The requirements to qualify information collected on each waste stream, whether by AK or by any other method described in 40 CFR 194.22(b), have not been established with specificity in the submittal documents. Recommendation: In the site-specific accompanying documents, DOE should present clear and technically defensible data qualification requirements for its RH-TRU waste characterization plan. Rationale: The committee recommends that DOE follow a more structured approach in the development of its characterization plan. A structured approach, such as that provided by defining data quality objectives and quality assurance objectives, would clearly define the data needed for characterization, identify the basis for the data need, and then logically determine how to meet those needs. The committee does not expect quantitative quality assurance objectives, especially for AK information. However, it is important to discuss how to determine when or whether AK could meet data quality objectives and under which conditions it would be necessary to supplement AK using other characterization methods (e.g., dose to curie conversion, visual examination, radiography, time of packaging methods, direct assay, surface dose rate). This recommendation is also consistent with the recommendation of a second peer review on DOE’s characterization plan.7 According to the information gathered, DOE will submit to EPA and NMED along with the draft characterization plan, a sample of completed characterization documents for three RH-TRU waste generator sites (Energy Technology Engineering Center, Battelle Columbus Laboratories, and Oak Ridge National Laboratory). The committee supports this initiative. These companion documents to the characterization plan should be useful in clarifying the intended methods of implementation. The committee could not review these methods, given that these documents were not available at the time this report was written. Finding 2C: DOE’s proposed characterization plan does not adequately address the issue of tolerable decision error rates associated with all characterization information. Recommendation: DOE’s proposed characterization plan should address tolerable decision error rates associated with characterization information. These errors should not be overly stringent so as to negatively impact the sites’ ability to implement ALARA. Rationale: Tolerable decision error rates are never clearly defined in Document 1 and Document 2. Tolerable decision error rates are determined by weighing the consequences of mischaracterization against the costs (including worker risks) of achieving better characterization. Once established, tolerable decision error rates can be 7   The Institute for Regulatory Sciences, which reviewed the July 2001 draft of DOE’s proposed characterization plan, recommended the following: “A detailed procedure for determining whether there is sufficient AK available on a waste, should be developed as part of the permit application. This procedure should be consistent across all waste generating sites. […] [A] detailed procedure should be provided to go to other characterization methods if AK is found to be insufficient” (Institute for Regulatory Sciences, 2001; page 77).

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report used to identify the attendant quality assurance requirements for sampling (i.e., the measurement quality objectives, which DOE calls quality assurance objectives). Tolerable decision error rates may not be specified in laws and regulations, but they are a critical judgment that an implementer should propose when interpreting legal or regulatory limits to address the uncertainties inherent in characterization data. As an illustration, Document 1 reads as follows: “Tolerable decision error: The limit on residual liquids has been specified with no associated error; therefore, any container that contains more than 1 percent by volume residual liquids cannot be shipped to WIPP” (DOE-CBFO, 2002a; Attachment B; page 7). The tolerable decision error (and its rate) in the measurement of the liquid volume in a container is never clearly defined. More importantly, the above quote from Document 1 seems to suggest that there is a zero tolerable decision error (and a zero tolerable decision error rate) on the determination of residual liquids. Another example of unclear tolerable decision error rate concerns the quantification of the total activity. The March 2002 draft proposes to use the same quality assurance objective for the total activity of waste as the one used for CH-TRU waste (see Chapter 4, Section 4.6). However, the committee still cannot determine with clarity what is tolerable decision error rate associated with the measurement of the total activity. It is premature for DOE to develop quality assurance objectives until it has proposed tolerable decision error rates that limit risks related to the waste, and that recognize potential tradeoffs in costs and worker risks. Without setting tolerable decision error rates to create a bridge between the data quality objectives and the characterization methods, it will be impossible to determine whether the waste characterization plan requires too much or too little in terms of the quality of the data needed. The quality assurance objectives should be presented in the site-specific implementation plans and could vary from site to site. The committee supports DOE’s plan to submit to EPA and NMED the three site-specific (Energy Technology Engineering Center, Battelle Columbus Laboratories, and Oak Ridge National Laboratory) implementation plans. It is important to recognize that tolerable decision error rates will have an impact on characterization operations at the generator sites. The ALARA principle must be applied at DOE facilities according to the Code of Federal Regulations (10 CFR 835.101). Therefore, the proposed characterization plan should not set forth overly stringent requirements (such as zero tolerable decision error rates) that could negatively impact the sites’ ability to implement ALARA (see also Finding 3A). Finding 2D: It is not clear how visual examination and radiography can confirm AK information for prohibited items. For example, visual examination and radiography cannot distinguish between corrosive and non-corrosive liquids, whereas AK may provide records of the existence of such liquids in the waste. Historical AK may be a better indicator of some of the currently prohibited items than visual examination and radiography. Recommendation: The characterization plan should clarify under which conditions confirmation of historical AK is warranted and what are the most effective methods proposed. Rationale: This finding applies to the approximately the 5 percent of the RH-TRU waste inventory that does not require packaging or repackaging. The committee observes that the March 2002 draft better explains how AK could be, in some cases, the most suitable method to determine the absence of certain prohibited items. In this draft,

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report DOE proposes to use AK to identify hazardous waste codes to prevent ignitable, corrosive, and reactive waste from being disposed of in WIPP. However, DOE does not clearly explain under what circumstances AK should be confirmed and what are the results expected from supplementary characterization methods. DOE recognizes that visual examination and radiography are inadequate techniques for addressing the entire list of prohibited items. From the operational experience acquired with CH-TRU waste, it is possible to obtain some indication of the effectiveness of AK as a characterization method. Most of the information collected for CH-TRU waste characterization consists of historical records about waste streams, which the committee termed “historical AK” (see Sidebar 2.1). Effectiveness of AK for CH-TRU waste is demonstrated by the “AK Information Accuracy Reports” from the various generator or storage sites (DOE-CBFO, 2001c). DOE presented to the committee the results of an analysis of the effectiveness of historical AK for CH-TRU waste. Contact-handled TRU waste generators use radiography or visual examination, headspace gas sampling and analysis, and/or solids sampling and analysis to confirm AK information accuracy. Results showed a high accuracy of historical AK: above 95 percent for the determination of waste matrix codes at the major CH-TRU waste generator sites and above 93 percent for the determination of hazardous waste codes. The only exception was observed at the Idaho Environmental and Engineering Laboratory, where an accuracy of 80 percent was achieved in the hazardous waste codes determination. This lower accuracy was obtained because this site assigned hazardous waste codes on a waste stream basis, rather than on an individual container basis. Document 2 provides further feedback on AK confirmation for CH-TRU waste by headspace gas analysis: “To date, the headspace gas from over 16,000 CH TRU waste containers has been sampled and analyzed and no hazardous waste numbers have been added to a waste stream. This indicates that the additional benefit from using headspace gas sampling and analysis to confirm the hazardous waste determination are limited” (DOE-CBFO, 2002b; pages 5–21). The committee emphasizes that these effectiveness analyses provided by DOE are relevant only to AK for CH-TRU waste, which is historical AK. In the case of the 95 percent of RH-TRU waste, most of the information comprising AK will be collected during waste generation or repackaging under a certified quality assurance program and would likely have higher accuracy. Finding 2E: DOE’s characterization plan calls for application of specific technologies, such as X-ray radiography, to provide confirmatory data. The committee could not determine the effectiveness of these technologies in characterizing the high-dose-rate fraction of RH-TRU waste containers. Recommendation: DOE should provide justification for the technologies proposed for obtaining confirmatory data and provide evidence of their effectiveness across the entire spectrum of dose rates for RH-TRU waste. Rationale: Given the importance placed on radiography to determine the presence of prohibited items, the characterization plan should clarify and support the information on the method’s effectiveness in high radiation fields expected for a small fraction of RH-TRU waste. The lack of information on the effectiveness of characterization methods for RH-TRU waste was also NMED’s main argument to prohibit this type of waste in WIPP

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report (see Chapter 3). Moreover, this recommendation is consistent with the Institute for Regulatory Sciences’ peer review of the July 2001 draft of the characterization plan.8 In Documents 1 and 2, the committee did not find adequate justification for the effectiveness of technologies proposed for obtaining confirmatory data, such as radiography, particularly for RH-TRU waste with higher surface dose rates. In its response to the committee’s interim report, DOE states: “For the minimal use of NDA [non-destructive assay] and RTR [real-time radiography] that will still be required in the overall program, the standard technologies currently being employed in the CH-TRU waste program are more than adequate. The RH Team recommended program […] calls for NDE [non-destructive examination] to be used only to detect 1 [percent] residual liquid and only for a small percentage of the total RH-TRU waste inventory (most RH-TRU waste will be repackaged or newly generated). Resolution of current RTR systems, even in high radiation fields, is adequate for this determination” (see Appendix H). DOE never addresses the issue of the fraction of waste containers with high surface dose rates. The current DOE inventory in Table 2.1 shows that both the Hanford Site and Oak Ridge National Laboratory have or will generate RH-TRU waste with a surface dose rate as high as 1,000 rem per hour. Moreover, some Oak Ridge National Laboratory RH-TRU waste also emits neutrons, which further complicates non-destructive characterization methods. In Documents 1 and 2, radiography is cited as lead technology to confirm AK, where necessary, or to examine the contents of small containers prior to placing them into the final shipping containers. DOE’s proposal to use radiography across the entire spectrum of dose rates warrants an explanation, however small the fraction of high dose-rate containers may be. The committee was unable to find elsewhere information on whether radiography could be used for RH-TRU waste containers with the highest dose rates. DOE indicated to the committee that: “Though DOE collected some data and analysis indicating that there are no fundamental obstacles to radiographing RH TRU wastes, there has not been a systematic demonstration of that capability. As a consequence, there is lingering doubt regarding its feasibility in general. The simplest means to put these doubts to rest is to design and perform a systematic evaluation” (Taggart, 2001). The committee gathered additional information on non-destructive characterization techniques and there appear to be uncertainties and technical difficulties in high radiation fields (see Appendix G). Under the committee’s request for additional information, DOE provided a publication on X-ray radiography applied to RH-TRU waste characterization (Roney and White, 2001). This study, although performed on surrogate waste, showed that X-ray technology could indeed investigate the content of RH-TRU waste drums, although it was discussed for surface dose rates only up to 100 rem per hour. It is unfortunate that this study is not mentioned in DOE’s characterization plan. To 8   The Institute for Regulatory Sciences recommended: “More detail and specificity on WAC [waste acceptance criteria] using AK, VE [visual examination], and [Radiography (including types of instrumentation to be used) should be provided in the permit application” (Institute for Regulatory Sciences, 2001; page 77).

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report the best of its knowledge, the committee believes that the application of radiography in the presence of very high radiation fields may be problematic. Other non-destructive assay and examination techniques are being developed for the characterization of RH-TRU waste (see Appendix G). According to the information gathered, the only example of non-destructive assay characterization performed on actual RH-TRU waste was the characterization of 10 canisters of RH-TRU waste at Los Alamos National Laboratory. This was done using a passive/active neutron assay technique (Estep et al., 1989). Further development and application of non-destructive assay and examination techniques is pending the outcome of the final RH-TRU waste characterization plan. 5.3 Protection of Worker Safety and Health The main issues concerning the handling of RH-TRU waste are potential radiation worker doses and assorted characterization costs. Finding 3A: Potential worker radiation doses and related characterization costs are distinguishing features of RH-TRU waste compared to CH-TRU waste. Available estimates of worker doses and characterization costs for RH-TRU waste are limited, site-specific, and not completely reliable. Recommendation: DOE could strengthen the rationale of its characterization plan for RH-TRU waste by incorporating a discussion of estimates of worker doses and characterization costs in the three site-specific plans accompanying the submittal documents. Rationale: The committee observes that the data presented on waste dose rates and characterization cost estimates in the July 2001 draft have been removed from the March 2002 draft. The committee recognizes that, since the characterization plan for RH-TRU waste is not yet finalized, information on worker doses and characterization costs for RH-TRU waste is scarce. The only data available on RH-TRU waste are from Battelle Columbus Laboratory, WIPP, and Argonne National Laboratory-East, and they may not be representative of all RH-TRU waste generator sites (see Appendix H). The committee also recognizes that the sites are also responsible for applying the ALARA principle to minimize radiation doses to workers during characterization operations. It follows that each site will produce a different implementation plan for waste characterization and worker radiation protection programs based on ALARA will also be different. However, a risk perspective of worker doses and costs could be illuminating in developing characterization requirements and in adding credibility to the plan. Discussion of worker doses and costs is relevant since radiation protection standards and criteria are predicated on the concept of assessing the decrement in risk per increment in cost as outlined by the International Commission on Radiological Protection (ICRP, 1977). The approach to estimate worker doses would be to structure different scenarios, rank the scenarios on the basis of the supporting evidence, and calculate the worker doses. This type of dose information would add much to the discussion of the differences between CH- and RH-TRU waste characterization plans. An equivalent approach could be adopted to better estimate characterization costs. The committee recommends that the estimated doses and costs be an integral part of the three implementation plans from representative generator sites that will accompany Documents 1 and 2. Understanding worker doses and underlying characterization costs is important in developing effective radiation protection programs

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report based on the ALARA principle. The committee provides in Appendix H examples of estimates of worker doses and characterization costs. In Section 5.2, the committee also recommended that DOE’s characterization plan should not set forth overly stringent tolerable decision error rates that could negatively impact the sites’ ability to implement ALARA (see Finding 2C). Finding 3B: The submittal documents provide flexibility to the generator sites in the implementation of the RH-TRU waste characterization plan. Recommendation: DOE should continue its effort in ensuring sufficient flexibility to generator sites in the implementation of the characterization plan. However, characterization activities that share common elements across sites should be standardized. Rationale: One of the findings of the committee’s interim report is that there is substantial variability among RH-TRU waste generator sites, including: variability in the composition of the waste streams; variability in the extent of AK available; variability in the characterization and repackaging facilities available; and variability and uncertainties in the current and projected inventories of RH-TRU waste. The committee acknowledges that the March 2002 draft better addresses the substantial RH-TRU waste variability from site to site compared to the earlier draft. DOE’s characterization plan allows flexibility to the generator sites in implementing the RH-TRU waste characterization program. In Document 1, DOE directs each TRU waste site to develop standard operating procedures to implement the waste characterization plan at that specific site (DOE-CBFO, 2002a; Section 3.2.2 of Attachment B). DOE also addresses data validation, usability, and reporting at the individual sites in Section 3.5 of Attachment B. Also, Attachment 6 of the application is designated “Site Specific Documentation,” but this section has yet to be written. Document 2 requires the sites to develop their own RH-TRU mixed waste characterization programs in compliance with the requirements of the overall waste analysis plan (Document 2, Section R 4.0). These programs are to include characterization strategies, equipment, and health and safety protocols; site-specific characterization methods; quality-assurance plans; and training programs. Flexibility in a waste characterization plan is important to allow the sites to adapt each characterization requirement to their type of waste inventory and characterization facilities. A rigid, overly prescriptive characterization plan may lead to unnecessary radiation doses to workers and characterization costs. For example, small sites that do not have adequate characterization facilities may find themselves in a difficult situation if the characterization plan mandates specific confirmatory activities, even in the presence of adequate AK. If the site must perform confirmatory measurements or visual examination in a hot cell it would have to ship its waste to a different site9 equipped with a hot cell or use a mobile hot cell. Therefore, the added costs of such confirmatory measurements could be significant. The committee reiterates its recommendation that common elements among the sites be standardized to facilitate characterization compliance verifications and, possibly, reduce characterization costs. In the effort of standardizing characterization activities, 9   Shipments from site to site are allowed before the waste characterization plan is approved because DOE’s waste characterization plan applies only to waste shipped to WIPP.

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report DOE will submit to EPA and NMED a sample of completed characterization documents for three RH-TRU generator sites (Energy Technology Engineering Center, Battelle Columbus Laboratories, and Oak Ridge National Laboratory). The committee supports this initiative. The committee observes that, in the sites’ inventories description, DOE did not differentiate mixed RH-TRU waste from non-mixed RH-TRU waste. DOE indicated that, although some waste streams could be identified as non-mixed RH-TRU waste, all waste is deliberately treated as mixed RH-TRU waste, as a policy decision. In fact, according to the RCRA Permit, all waste emplaced in WIPP (mixed or non-mixed) must be analyzed according to a characterization plan approved by NMED (DOE-CBFO, 2002c). The committee acknowledges DOE’s policy decision, although it lacks a technical basis. 5.4 Compliance with Regulatory Requirements The committee evaluated how DOE proposes to address EPA and NMED requirements from a technical point of view. The committee was not asked to determine if the plan complies with the regulatory requirements. The latter is obviously a policy decision that belongs to the regulatory agencies. One of the challenges of this characterization plan is to meet characterization requirements specified in the EPA Certification and RCRA Permit that were negotiated with WIPP’s regulatory agencies for CH-TRU waste and exclude RH-TRU waste. Moreover, the only TRU waste characterization plan approved by EPA and NMED is that currently used for CH-TRU waste. With this characterization plan DOE proposes to meet EPA and NMED requirements following a different approach than that used for CH-TRU waste. Finding 4A: The proposed characterization plan for RH-TRU waste deliberately tracks the characterization plan for CH-TRU waste. Recommendation: DOE should evaluate whether existing characterization practices for CH-TRU waste, when applied to the characterization of RH-TRU waste, have an impact on the protection of the environment, health and safety of public and workers, and cost-effectiveness of the characterization program. Rationale: DOE proposes to address regulatory requirements for RH-TRU waste characterization using a performance-based approach, a different approach than that used for CH-TRU waste. The committee observes that the characterization plan for RH-TRU waste has not yet been finalized. The implementation activities for RH-TRU waste to address characterization objectives will be finalized only after negotiations based on the submittal documents take place between DOE and WIPP’s regulatory agencies. However, the existence of a characterization plan for CH-TRU waste does not imply that the same approach should be proposed for the characterization of RH-TRU waste. It is not the committee’s intention to say that there are unnecessary regulatory requirements in the current EPA Certification and RCRA Permit. However, there is reason to believe (Kehrman, 2002; NRC, 2001 a; DOE, 1999a) that DOE proposed some characterization practices in the CH-TRU waste characterization plan to facilitate negotiations with the regulatory agencies and obtain authorization to operate the WIPP facility. The previous National Research Council committee on WIPP found that some of these self-imposed practices lacked a technical, safety or legal basis (see Sidebar 3.1). The current committee emphasizes that, because of the additional radiological and cost

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report considerations associated with RH-TRU waste, it is even more important that DOE refrains from proposing characterization requirements that do not have a technical, health and safety, or regulatory basis. Given the different context of RH-TRU waste characterization described earlier, the committee acknowledges that DOE’s efforts to introduce a performance-based approach are technically justified. However, the committee does not find the proposed plan to be completely performance based (see Finding 1A). The committee does not suggest that DOE should do only the “bare minimum” to characterize RH-TRU waste. Rather, the characterization program should ensure repository integrity, protection of the environment and of the health and safety of the public and workers, while keeping in consideration tradeoffs between greater characterization accuracy and worker risks. Finding 4B: The submittal documents include, as basis for characterization objectives, waste acceptance criteria and other requirements than those applicable to the EPA Certification and RCRA Permit. Recommendation: Submittal documents should focus on regulatory requirements under the relevant agency’s purview and should distinguish between these requirements and ancillary information describing the context of RH-TRU waste characterization. Rationale: Document 1 contains the RH-TRU Waste Acceptance Requirements and Criteria. These are the “controlling (i.e., the most restrictive) requirements to be used by the sites in preparing their waste for transportation to and disposal at the WIPP” (DOE-CBFO, 2002a; Section 3.0 of Attachment A). The waste acceptance criteria are drawn from transportation and hazardous waste considerations, as well as repository-performance considerations. For instance, the waste transportation quality assurance requirements are described in Section 4.3 of Attachment A. Since Document 1 is an application for a change in the EPA Certification, it is not clear why requirements and criteria other than those relating to repository performance are given in the document. Historically, DOE included the waste acceptance criteria in the characterization plan for CH-TRU waste (DOE-CAO, 1996a). This does not need to be the case for the RH-TRU waste characterization plan since, to the best of the committee’s knowledge, EPA does not require these criteria to be part of the application. Documents 1 and 2 also contain requirements originating from the Nuclear Regulatory Commission, the Department of Transportation, and the Occupational Health and Safety Administration. While it is important to provide the regulatory agencies the full context of RH-TRU waste characterization, including in the submittal documents material outside the regulatory jurisdiction of EPA and NMED may unnecessarily complicate the regulatory review process. In the future, DOE may wish to negotiate other requirements with different regulatory agencies than EPA and NMED (for instance, transportation requirements with the Nuclear Regulatory Commission and the Department of Transportation). These negotiations could become more complex if the original requirements had also become a part of a document reviewed and approved by the EPA or NMED. See also the comment on polychlorinated biphenyl limits discussed in Finding 2A, example #5. The committee believes that it would be helpful for both DOE and the regulatory agencies if the submittal documents indicate which requirements are to be reviewed and which are given for information purposes. This would allow the regulator and the implementer (DOE) to keep track of various requirements, and to streamline characterization practices as experience is gained. This recommendation applies to the submittal documents only. The committee supports the current practice of combining all

OCR for page 47
Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant: Final Report regulatory requirements into one document to guide generator sites in the development of their characterization programs. 5.5 Overall Assessment of DOE’s Characterization Plan The committee observed a net improvement between the July 2001 and March 2002 drafts of the characterization plan. Concerning the plan’s technical soundness, DOE itself recognized that this plan is not completely performance based and that several other considerations played a role in the development of this plan. The committee identified some characterization activities lacking technical bases in the context of RH-TRU waste and a potential technical problem with radiographic examination of waste. Also, DOE’s proposed characterization plan does not adequately address the issue of tolerable decision error rates associated with all characterization information. In some instances, the plan lacks specificity because most of the operational details are site-specific and were not available at the time of writing. The site-specific accompanying documents should provide useful clarifications. In the context of RH-TRU waste characterization and from a performance point of view, the committee found that the general approach DOE is proposing is technically sound. However, Documents 1 and 2 do not present a performance-based plan as effectively as they could. Concerning the plan’s protection of worker health and safety, the committee recommends that the approved characterization plan not include overly stringent tolerable decision error rates that could negatively impact the sites’ ability to manage worker risks. It is important to recognize that the allowable uncertainties in the final characterization plan approved by EPA and NMED may have an impact on generator sites’ radiation protection programs. Concerning compliance with regulatory requirements in the EPA Certification and RCRA Permit, the committee did not observe any requirement that was not addressed in DOE’s characterization plan. In fact, the proposed characterization plan for RH-TRU waste addresses some requirements that are not under the relevant agency’s purview. Moreover, the characterization plan for RH-TRU waste deliberately tracks as close as possible that for CH-TRU waste. The committee recommends evaluating whether existing characterization practices for CH-TRU waste, when applied to the characterization of RH-TRU waste, have an impact on the protection of the environment, health and safety of public and workers, and cost-effectiveness of the characterization program.