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B.2.0 DEVELOPMENT OF ALTERNATIVES

This section explains the process that was followed to develop alternatives for remediating the tank waste, implementing the alternatives for remediating the tank waste, and remediating the cesium and strontium capsules. This section also discusses the TWRS activities that are not included in the EIS.

B.2.1 TANK WASTE

B.2.1.1 TWRS Elements

Final remediation of TWRS involves three distinct activities: remediating the tank waste; dispositioning the tanks and all associated equipment (a process called closure); and decontaminating and decommissioning any new facilities constructed to remediate the tank waste. These activities are described in the following text.

Remediating Tank Waste

Remediating the tank waste involves those activities associated with remediating the waste in 177 underground tanks and approximately 60 MUSTs. The activities required to remediate this waste is the subject of this EIS. Volume One, Section 3.3. describes the process followed to select alternatives for inclusion in this EIS. The remainder of the EIS provides information relative to the environmental impacts of the alternatives addressed.

Dispositioning the Tanks (Closure)

The final disposition of the tanks and associated equipment and the remediation of contaminated soil and groundwater associated with leaks from the tanks is a process called closure. Closure is not within the scope of this EIS because there is insufficient information concerning the amount of contamination that would need to be remediated. For purposes of comparing the alternatives, a single and consistent method of closure was assumed for all of the alternatives. Closure as a landfill was chosen as the representative closure method for purposes of analysis and is included in all of the alternatives (except the No Action and Long-Term Management alternatives). This does not mean that closure as a landfill is proposed or necessarily would be selected in the future. It is included to allow a meaningful comparison of the in situ and ex situ alternatives and to provide information to the public and the decision makers of the total cost and impacts of final restoration of the Site.

Decontamination and Decommissioning

Decontamination and decommissioning of any new facilities constructed to implement any of the alternatives is not evaluated in detail in this EIS because the decisions on the appropriate method to accomplish decontaminating and decommissioning the facilities would not be required until the treatment and disposal of waste was completed, which is up to 30 years in the future. Insufficient information is available at present to provide meaningful evaluation; however, decontamination and decommissioning of these facilities is foreseeable. Therefore, the costs, personnel requirements, and volume of contaminated and noncontaminated materials resulting from decontamination and decommissioning are included in each alternative to show how tank waste remediation and decontamination and decommissioning are interrelated.

B.2.1.1.1 Development of Alternatives

A wide range of potentially applicable technologies exists for treating tank waste. One of the challenges for DOE and Ecology is to eliminate technologies that are not viable and develop a range of reasonable alternatives for presentation in the TWRS EIS. This section describes how the alternatives were developed.

There is a distinction between technologies and alternatives. Technologies are specific processes (e.g., cesium ion exchange) that relate to a component (e.g., retrieval or treatment) of an alternative. Alternatives include a set of technologies, or building blocks, that have been engineered to work together, forming complete systems for accomplishing the purpose and need for action. Alternatives are made up of a number of technologies linked together.

The first step in developing alternatives was to screen out technologies that were not viable. The full range of available technologies for each component of the proposed action was evaluated, and technologies that were not viable were eliminated from further consideration. The technologies eliminated by this screening process are described in Volume One, Section 3.8 and Volume Two, Appendix C.

After rejecting technologies that were not viable, a large number of potential technologies remained for inclusion in the EIS. It would not be possible to develop alternatives that include all of the potential combinations of technologies. In accordance with NEPA, representative alternatives were developed to bound the full range of reasonable alternatives (10 CFR 1500). Upper, lower, and intermediate bounding alternatives were developed in terms of cost, risk, and technologies for the two primary decisions that affect environmental impacts: the amount of waste to be retrieved from the tanks and the degree of separation of retrieved waste into HLW and LAW. The full range of applicable technologies and alternatives is included in the EIS.

Because representative alternatives were developed to support detailed analysis in the EIS, there are many other viable technologies for individual components of the alternatives that could not be included in the detailed analysis. These technologies are included in Section B.9 and could be substituted for one of the technologies that is included in an alternative without a substantial change in the impacts of that alternative. An evaluation was performed of each of the technologies identified in this appendix. Most of these technologies would have little change on impacts. Where there were changes in impacts, the changes were discussed. The level of analysis was dependent on the magnitude of the change on impacts.

The alternatives developed for presentation in the EIS were chosen to be representative of many of the possible variations of the alternative. The design information for all alternatives is at an early planning stage, and the details of the alternative that ultimately is selected and implemented may change as the design process matures. Therefore, the alternatives are intended to represent an overall plan for remediation at a level of detail sufficient for impact analysis and alternative comparisons.

NEPA requires that an EIS include a No Action alternative, which addresses the alternative of not taking the proposed action (i.e., not initiating the project). For the TWRS project, there is a management program in place to continue the safe management of the tank waste and the capsules; therefore, the No Action alternative addressed in this EIS (continue the current waste management program) consists of the activities currently being conducted to safely manage the waste. Further, under the No Action alternative, no new facilities would be constructed other than those for which decisions already have been made based on other NEPA reviews (e.g., the SIS EIS).

Since the late 1950's, there have been numerous studies analyzing alternatives for tank waste treatment and disposal. The technologies that have contributed to the development of the alternatives presented in the EIS come from different sources. One of the main sources of information is the Tank Waste Technical Options Report (Boomer et al. 1993). The initial set of technologies used in the report was obtained by reviewing literature for processing radioactive, hazardous, and mixed waste. The literature review was supplemented by several DOE-sponsored workshops on treatment technologies for Hanford Site tank waste. Objectives and technologies were also proposed for consideration in the EIS during the public scoping process.

Four general categories of response actions have emerged through the alternative identification process. These categories are 1) continued safe management of the tank waste; 2) waste treatment and disposal in the tanks, referred to as in situ treatment; 3) waste treatment outside of the tanks in a processing facility, referred to as ex situ treatment; and 4) a combination of in situ and ex situ treatments. In situ waste treatment would not involve removing the waste from the tanks. In situ alternatives eliminate the need for any waste retrieval and would result in leaving all of the waste onsite following treatment. Ex situ treatment would require that the waste be removed from the tanks for treatment and disposal. Ex situ alternatives provide the opportunity for separating the waste into HLW and LAW components. The purpose of separating the waste is to minimize the volume of HLW requiring offsite disposal. Combination alternatives provide the opportunity to selectively retrieve waste for ex situ treatment based on waste type to achieve acceptable post-remediation risk levels.

Ex situ alternatives allow for geologic disposal of HLW at a potential geologic repository. Solely for the purpose of analysis, the potential geologic repository at Yucca Mountain, Nevada was assumed to be the final destination because it is currently being characterized to determine its suitability as a repository. It was assumed that the potential geologic repository would be operational and accept HLW generated by the ex situ alternative (see Section B.10.0 for additional details) .

In January 1994, DOE, Ecology, and EPA renegotiated the Tri-Party Agreement, which led to a new proposed technical strategy for remediating the tank waste. This technical strategy provides the basis for the TWRS EIS Ex Situ Intermediate Separations alternative and includes the following activities:

• Retrieve present and future waste from all DSTs and SSTs;
• Separate the waste into high-level and low-activity streams to the extent required to meet onsite disposal requirements for LAW and maintain an acceptable volume of HLW for offsite disposal;
• Vitrify the LAW and dispose of it onsite in a near-surface disposal facility in a retrievable form; and
• Vitrify the HLW and store it onsite at a designated interim storage facility for future disposal at the potential geologic repository.

B.2.1.1.2 Implementation of Alternatives

There are many technical uncertainties associated with all of the alternatives for remediating the tank waste. These uncertainties include the types of waste contained in the tanks and the effectiveness of the retrieval techniques, waste separations, waste immobilization, and cost of implementing the alternatives. These uncertainties exist because some of the technologies that may be implemented are first-of-a-kind technologies, and have not previously been applied to the TWRS tank waste, or have not been applied on a scale as large as would be required for the TWRS tank waste.

Because of these uncertainties, DOE considered different approaches to implementing the alternatives to reduce the financial risk involved if one or more of the technical uncertainties could not be readily resolved. DOE identified two approaches to implementing the alternatives: full-scale implementation and phased implementation. Under full implementation, either DOE or a private contractor would design, construct, and operate full-scale facilities to remediate the tank waste. Under phased implementation, DOE or a private contractor would design, build, and operate demonstration-scale facilities to prove that the remediation concept would function adequately before constructing and operating a full-scale facility. All calculations performed for this EIS are based on DOE implementing the alternatives through the existing Management and Operations Contractor system. This phased implementation approach has the potential to prove that the technologies work before committing large capital expenditures that could not be recovered.

A phased approach could be developed for any of the alternatives but not all phased approaches would involve changes to environmental impacts from the full-scale approach. Therefore, not all phased approaches need to be addressed in the EIS. To decide which of the full-scale alternatives would need to have an associated phased implementation alternative addressed in this EIS, the following two criteria were used.

• Would the full-scale alternative involve large front-end expenditures of funds that could be lost if an unproven technology did not function adequately?
• Would the environmental impacts of the phased implementation approach be different than those of the full-scale alternative?

If either criterion was met, a phased approach would be included in the EIS.

Applying these criteria showed that most alternatives did not warrant a separate analysis of a phased implementation approach. A phased implementation approach to the No Action and Long-Term Management alternatives would not involve changes in environmental impacts, large front-end expenditures, or unproven technologies, so no phased approach was included in the EIS for these alternatives. A phased implementation approach to the In Situ Fill and Cap alternative would involve the simple process of filling several tanks as a demonstration, and therefore would not involve different environmental impacts or large front-end expenditures of funds that could be lost, so no phased approach was included in the EIS. Similarly, a phased approach to the In Situ Vitrification alternative would involve testing the in situ vitrification process first on MUSTS, then small tanks, and then large tanks. Although this technology previously has not been performed on the tank waste, it could be tested gradually without any differences in environmental impacts or large expenditures of funds that could be lost if the process did not function adequately. Therefore, the In Situ Vitrification alternative did not warrant a separate phased implementation alternative, and no phased approach was included in the EIS.

All of the ex situ alternatives involve the application of technologies that have not been applied to the tank waste, and all would involve large front-end expenditures of funds to construct large, complex separations and immobilization facilities. The phased implementation approach for these alternatives would involve constructing and operating demonstration-scale facilities prior to constructing the full-scale facilities, and therefore would result in environmental impacts substantially different than the full-scale implementation alternative. Therefore, a Phased Implementation alternative has been included in the EIS to bound the impacts for the ex situ alternatives.

The Phased Implementation alternative consists of two phases: a proof of concept or demonstration phase (Phase 1) and a full-scale treatment phase (Phase 2). Phase 1 would include the construction and operation of one combined separations and LAW vitrification facility and one combined separations, LAW vitrification, and HLW vitrification facility. Enough waste would be remediated to prove that the many waste types in the tanks could be remediated effectively. Phase 2 would include completing tank waste remediation by constructing and operating new full-scale separations, LAW immobilization, and HLW vitrification facilities. The degree of separations into LAW and HLW was assumed to be similar to the Ex Situ Intermediate Separations alternative and includes additional processes to separate out the Sr, Tc, and TRU elements.

The following tank waste alternatives are addressed in this EIS:

• No Action;
• Long-Term Management;
• In Situ Fill and Cap;
• In Situ Vitrification;
• Ex Situ Intermediate Separations;
• Ex Situ No Separations;
• Ex Situ Extensive Separations;
• Ex Situ/In Situ Combination 1 ;
• Ex Situ/In Situ Combination 2; and
• Phased Implementation (preferred alternative).

The alternatives developed for detailed analysis cover the full range of actions as well as the No Action alternative. The tank waste alternatives range from waste containment with the Long-Term Management alternative to extensive processing (separating HLW from LAW fractions) and immobilization using new technologies with the Ex Situ Extensive Separations alternative. The relationship among the alternatives is shown in Figure B.2.1.1.

Figure B.2.1.1 Relationship Among TWRS EIS Alternatives

B.2.1.2 Cesium and Strontium Capsules

The Cs and Sr capsules are currently classified as waste by-product and this EIS is addressing only measures to remediate the capsules when an if they are determined to have no potential productive uses. The development of alternatives to remediate the Cs and Sr capsules is much less technically complicated than the tank waste. There are two distinct activities related to remediation of the capsules: the disposition of the capsules, which is the subject of this EIS; and decontamination and decommissioning of the current storage location of the capsules in WESF, which is part of B Plant. Decontamination and decommissioning of WESF would be performed with the remainder of B Plant and is not within the scope of this EIS.

The alternatives for remediating the capsules include No Action, disposal on the Hanford Site, or disposal off the Hanford Site either with or separately from the tank waste. None of these involve unproven technologies or the construction of major facilities. The following capsules alternatives are addressed in this EIS:

• No Action;
• Onsite Disposal;
• Overpack and Ship; and
• Vitrify with Tank Waste.