5
Conclusions and Recommendations

The primary objective of this study was to provide recommendations on an approach for identifying technology development needs for managing environmental contamination, especially the high-level waste (HLW) in large underground tanks at Department of Energy (DOE) sites. The recommended approach is based primarily on the systems engineering process with emphasis on end state requirements for remediation products. Consideration was given to alternatives for achieving different end states for a given initial remediation problem. The committee believes that the recommended approach can be applied to DOE waste remediation in general, not just to waste in tanks. While the proposed method is considered generic, the waste in the large underground Hanford tanks was used as an example to illustrate the approach. The example is not exhaustive, is for illustrative purposes only, and considers only selected steps in the Hanford functional flowsheets devised by the committee.

Since the focus of the committee's effort was on the method for identifying technology requirements, not on their application, the conclusions and recommendations are organized accordingly. In particular, priority is given to end state methodology, followed by insights obtained through application of the Hanford example. The committee also briefly comments on the Office of Environmental Management (EM) tank technology development program and the impact on this program of such external factors as privatization.

The End State Methodology

Conclusions

A systematic process for identifying technology development needs to support the cleanup of waste stored in large buried tanks is essential to economical and effective solutions to site remediation. The end state approach is a systematic and disciplined framework, based on the principles of systems engineering, for the identification of technology development needs.

The committee concludes that it is possible to specify a generic approach to determine waste-related technology needs that is based primarily on consideration of the end state of the waste. The approach is as follows:

  • Characterize the initial state or condition of the wastes and sites to be remediated (e.g., waste volume and constituents, applicable regulations).


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--> 5 Conclusions and Recommendations The primary objective of this study was to provide recommendations on an approach for identifying technology development needs for managing environmental contamination, especially the high-level waste (HLW) in large underground tanks at Department of Energy (DOE) sites. The recommended approach is based primarily on the systems engineering process with emphasis on end state requirements for remediation products. Consideration was given to alternatives for achieving different end states for a given initial remediation problem. The committee believes that the recommended approach can be applied to DOE waste remediation in general, not just to waste in tanks. While the proposed method is considered generic, the waste in the large underground Hanford tanks was used as an example to illustrate the approach. The example is not exhaustive, is for illustrative purposes only, and considers only selected steps in the Hanford functional flowsheets devised by the committee. Since the focus of the committee's effort was on the method for identifying technology requirements, not on their application, the conclusions and recommendations are organized accordingly. In particular, priority is given to end state methodology, followed by insights obtained through application of the Hanford example. The committee also briefly comments on the Office of Environmental Management (EM) tank technology development program and the impact on this program of such external factors as privatization. The End State Methodology Conclusions A systematic process for identifying technology development needs to support the cleanup of waste stored in large buried tanks is essential to economical and effective solutions to site remediation. The end state approach is a systematic and disciplined framework, based on the principles of systems engineering, for the identification of technology development needs. The committee concludes that it is possible to specify a generic approach to determine waste-related technology needs that is based primarily on consideration of the end state of the waste. The approach is as follows: Characterize the initial state or condition of the wastes and sites to be remediated (e.g., waste volume and constituents, applicable regulations).

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--> Identify reference and alternative remediation scenarios that each accomplish a general remediation objective of providing for the health and safety of the public and the environment. Specify waste forms and environmental and other required conditions of the desired end states for each of the relevant remediation products. The end state is often characterized by a complete set of product acceptance criteria or site closure specifications from each scenario or alternative scenario. Define the flowsheets for each alternative scenario in terms of the functions to be performed (but not a specific technology to be used) in transforming the initial waste into the desired end states. Combine essentially identical functions in the flowsheets into a unique set of functions. Significantly different functions in different flowsheets (e.g., substantially differing degrees of decontamination) should be represented separately. Allocate the end state specifications to each processing function as functional requirements. Assess the technology required to perform each function or operation. The lack of correspondence between the functional requirement and the current status of the technology yields technology development needs. When implementing the end state methodology, it is important to note that technology development typically requires several years to produce deployable results, depending on the initial state of knowledge and the technology status. In contrast, regulations, knowledge, and stakeholder values concerning remediation issues and decisions often change much more rapidly. An appropriate technology development program should be based on a range of plausible scenarios that is likely to include those finally selected for implementation. In particular, an end state based approach that considers a range of plausible scenarios will identify technology gaps and technology development needs associated with credible alternative flowsheets. Implementing such an approach will also identify uncertainties and potential improvements to the existing baseline flowsheet, if it exists, that can lead to more desirable scenarios. Other findings and conclusions of the committee regarding the end state based approach are as follows: The lack of a range of firmly defined, plausible end states increases the probability of failure to meet schedules, budgets, and technical requirements. This range of end states is also necessary to meet contingencies, externalities, and other factors. The lack of provisional end states, which could provide a basis for proceeding with an end state based approach in the absence of firmly defined end states to technology development, also hinders the rational identification and prioritization of technology development activities.

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--> It is not always necessary to consider alternative end states, as there may be circumstances where the end state is unlikely to change. This is not the situation at the Hanford Site or at many of the DOE defense nuclear weapons complex remediation sites. In establishing an appropriate technology development program, end state specifications can be grouped into those related to human health and ecological risk (e.g., safety, hazard), those related to cost and schedules (e.g., process reliability, performance, efficiency), and societal externalities (e.g., policy on allowable risks, desirable end state specifications, the role of privatization). To form the basis for a technology development program, these must be translated into specific requirements for each function. Some type of performance assessment (whether it is described as risk analysis, decision analysis, or systems analysis) for necessary in translating health and environmental risk-related end state requirements into quantitative specifications. Similarly, cost assessments and trade studies are necessary for translating cost-related end state requirements into quantitative specifications. However, the risk- and cost-related information necessary to establish specific end state specifications is often not available, so contingency approaches to establishing such information should be developed. Several risk studies have been conducted on possible remediation strategies at Hanford. From the information provided to the committee, any effect that such quantitative risk studies have had on the choice of these strategies was not apparent. Recommendations An end state based approach to establishing an appropriate technology development programing support of DOE's environmental management program should be adopted. In particular, this approach should encompass reference end states for each waste stream, plus plausible alternative end states for each waste stream to accommodate uncertainty and potential future programmatic changes. Sufficient technology development resources should be invested in scenarios involving alternative end states to provide reasonable assurance that a solution will be available in case unforeseen but all too frequent technical surprises or externally imposed changes make it impossible to implement the preferred baseline approach. DOE should consider alternative end states unless the remediation process is short-term and proven cost-effective technology exists. Detailed documentation of the various steps taken in implementing the end state based approach should be developed for use by the custodians of the waste, those engaged in technology development, and oversight groups. Circumstances where alternative end states are not considered should be well documented as part of the evidence base justifying the decision made. In addition, executive level documentation appropriate for decision makers, such as DOE senior management and the Congress, should be developed. If initial conditions or end states cannot be adequately specified, a plan leading to the timely resolution of the open items should be prepared and executed. In the interim, enabling assumptions regarding the initial conditions and desired end states of the waste should be developed and clearly stated, preferably by problem owners, but by technology providers if necessary. End states and related technology requirements will frequently have to be identified in

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--> the face of major uncertainties about costs, benefits, public acceptability, and other relevant factors. Cost-risk studies should be more widely used in remediation decision making that forms the basis for technology development in an end state based approach. In particular, such studies should be used both to determine what must be done to protect human health and the environment at reasonable costs and to identify activities that yield only minimal risk reduction and hence should be considered as candidates for possible elimination. The Hanford Example This illustrative application of the end state based methodology to the Hanford high-level radioactive waste tanks identifies potential technology needs in four functional areas. The functions considered in the technology assessment were enhanced sludge washing and vitrification offgas processing in the committee's reference scenario, and enhanced barriers and stabilization of the tank contents in an in situ remediation scenario. The committee recognizes that unaddressed technology needs for some of the functional areas are due to the decision by DOE to focus resources largely on the Hanford baseline flowsheet. Conclusions The functions required to reliably remediate Hanford tank wastes in the face of technical and institutional uncertainties and the required performance of each function can be determined by specifying a reference scenario corresponding to the Hanford baseline and two plausible bounding scenarios, and the associated end states of the products from each. This can be done despite substantial uncertainties in the end states, since Hanford has not fully defined the end state for its baseline flowsheet. Many of the technology needs for the committee's reference flowsheet for remediating the wastes in the Hanford tanks, which corresponds closely to the Hanford baseline flowsheet (subject to the unknown contents of the private sector flowsheet), have been identified by the DOE and its contractors. The committee has two concerns: (1) the apparent lack (i.e., the inability of the committee to find any objective evidence) of a systematic end state based process for ferreting out technology development needs and creating a basis for decision making, and (2) the lack of technology development for end states other than those for the Hanford baseline flowsheet. Enhanced Sludge Washing The diverse nature of the tank wastes suggests that no single enhanced sludge washing procedure will be effective for all of the tank wastes. In the course of its review, the committee found little information on the rates at which reactions will proceed, solids will be dissolved, or products will be formed as a result of enhanced sludge washing of actual waste. Some of these processes presently appear to be quite slow, occurring over days or weeks. Excessively long reaction times could have a large impact on process flowsheets and on the specific sequence of process steps. The formation of colloids

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--> (especially with respect to the actinides), gels, and precipitates, and the treatment of the full range of solids to be encountered and formed are also important issues not adequately addressed. Changing the valences of such elements as chromium to enhance their removal from sludges may result in deleterious changes of the valences of other elements, such as the actinides. Vitrifier Offgas Processing The committee found no Hanford-designated technology needs identified by the Site Technology Coordination Groups for vitrification offgas processing, nor are there relevant projects evident in the Tank Focus Area program or elsewhere in DOE EM. The primary technology development needs relate to preventing radioactive and toxic wastes from leaving the vitrifier offgas and to preventing deleterious buildup of both radioactive and non-radioactive solids in the offgas system. Technology needs include information on (1) a number of potentially troublesome phenomena (e.g., condensation, decomposition, reaction) related to the species and quantities that evolve from the vitrifier, (2) the processing of secondary wastes, (3) remote operations of offgas systems handling large volumes of gas from large vitrifiers, and (4) offgas cleanup processes. Enhanced Barriers for In Situ Disposal of Tanks Containing Unretrieved Wastes Barrier technology development is necessary to adequately mitigate the transport of specific radionuclides such as the long-lived technetium-99. There is no apparent technology development currently underway on enhanced barriers for closure of tanks from which waste has not been retrieved. Stabilization of Tanks and Their Contents In Situ There are no apparent technology development projects currently underway for stabilization of Hanford tanks from which the wastes have not been removed. Recommendation The end state based approach should be applied on a broad scale to comprehensively identify technology development needs. The need for such an assessment based on alternative end states is highlighted by the extensive uncertainty surrounding the entire tank closure program. Doe Tank Waste Remediation Technology Development Program Conclusions The committee finds that the scope and extent of the DOE tank waste remediation technology development program is large and varied, and that specifications for some of the final

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--> product forms (end states) are available. However, progress in providing technology necessary for remediation is impeded by the lack of complete definition of the requirements for both baseline and alternative end states of remediation scenarios. Technology development needs cannot be fully defined until these requirements are specified in adequate detail by the responsible programs in DOE EM. Some of the technology needs important to closure of tanks containing substantial amounts of waste may not have practical solutions immediately available and may require prolonged development efforts and contributions from carefully formulated programs. More basic research may be required in these cases to identify suitable technologies. Recommendations The DOE EM technology development program should make an end state based approach a functional part of the process for defining its work. Alternative scenarios including defined end states should be formulated and evaluated, and technology development unique to these scenarios should be pursued on a basis that is prioritized with the help of performance assessment results and additional knowledge from relevant scientific research. General Factors Conclusions Decision making related to technology needed for the remediation of high-level radioactive wastes in tanks must consider factors other than purely scientific and technical. These other considerations, referred to in this report as external factors, include the constraints on decision making that come from organizational changes, regulations, stakeholder agreements, congressional actions, etc. While external factors were not a focus of the committee's review, such issues as privatization and the DOE organization have a major influence on technical decisions. The privatization initiative diverts DOE attention from addressing some tank waste remediation technology development needs (e.g., vitrification offgas treatment). There is a lack of explicit strategy and policy statements by DOE on what its role in the technology development is in light of privatization. Recommendations The committee urges DOE's Office of Science and Technology to adopt broadly the end state based method of identifying technology requirements to reduce sensitivity to future uncertainties such as changes in regulations, budgets, policies, and program participants. Technology development activities with long lead times should be designed to transcend the effects of these inevitable changes.

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--> An end state based framework for making decisions about technology needs should be used to provide much needed visibility of the relationship of the various activities (including risk studies) to the final objectives. Given DOE's lack of experience in privatization of such major functions as research, development, and cleanup operations, the committee recommends parallel pursuit of technology development for an alternative to the current privatization strategy for the Hanford Tank Waste Remediation System. It is not considered prudent to rely totally on privatization to develop the required technologies for systems with the history and complexity of high-level radioactive waste in tanks. The uncertainties are great, and the chances for failure are too high not to pursue alternatives.