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Suggested Citation:"4. Summary." National Research Council. 2001. Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/10143.
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4

Summary

The committee is confident that the WIPP can meet its general performance objectives as requested by the certification process. However, uncertainties remain in the long-term performance of the repository. Some of the recommendations in this report were released in the committee's interim report (Appendix A1) to which the DOE has responded with a number of actions taken (see Appendix A2). The committee encourages implementation of the improvements suggested by the DOE to address its recommendations. In Chapter 2 and Chapter 3, the committee addresses some new issues concerning the operation and long-term safety of the WIPP and reiterates for emphasis some of the recommendations of the interim report. This chapter closes the study with an overarching finding and recommendation.

OVERARCHING FINDING

The committee finds that the monitoring of selected performance indicators during the estimated 35-year or longer pre-closure phase of the WIPP is needed to possibly enhance confidence in the long-term safety performance of the repository. Although 35 to possibly 100 years is a short time compared to the 10,000-year period of compliance, the committee believes that it is long enough to reduce the uncertainties in many critical performance parameters. The rates of important processes such as salt creep, brine inflow (if any), and gas generation are predicted to be highest during this period; therefore, monitoring during the pre-closure phase is particularly important. Moreover, the committee finds that there are a number of specific actions that can be taken in the National TRU Program to facilitate operation of the WIPP while increasing safety and reducing costs.

OVERARCHING RECOMMENDATION

The committee recommends that the DOE develop and implement a program during the pre-closure phase to monitor selected performance indicators that specifically relate to the creation of a radionuclide source term and to pathways for radionuclide transport. Monitoring should continue throughout the preclosure phase and longer, if possible. Emphasis in the monitoring should be on waste mobilization and

Suggested Citation:"4. Summary." National Research Council. 2001. Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/10143.
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Page 43

transport mechanisms, including brine inflow, gas generation, geochemical reactions, room sealing, and surface and subsurface hydrology. The committee recommends that the results of the on-site monitoring program be used to improve the performance assessment for recertification purposes. These results will determine whether the need for a new performance assessment is warranted. Given the uncertainties, it is impossible to predict if the results of the monitoring program will be different than those modeled by the performance assessment. However, it is important to ensure that, if there are changes, these will be detected.1 Moreover, actions should be taken to improve and better define the National TRU Program for issues related to waste characterization and packaging requirements, total inventory of organic materials, communication and notification system, emergency response training, and gas generation during transportation.

The committee did not have all of the information necessary to prioritize the issues mentioned in this report. However, it has provided a selected number of recommendations that are believed to improve the operation and long-term safety of the WIPP. The committee recognizes that the recommendations in this report will have some economic impact on the transuranic waste management program. The DOE needs to balance costs against the improved assurance of facility performance in the longer term.


1Only measurable changes are important to verify the performance of the repository; for instance, a few drops of brine do not imply that the repository is not in compliance with containment requirements.
Suggested Citation:"4. Summary." National Research Council. 2001. Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/10143.
×
Page 42
Suggested Citation:"4. Summary." National Research Council. 2001. Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/10143.
×
Page 43
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The Waste Isolation Pilot Plant (WIPP) is a deep underground mined facility for the disposal of transuranic waste resulting from the nation's defense program. Transuranic waste is defined as waste contaminated with transuranic radionuclides with half-life greater than 20 years and activity greater than 100 nanocuries per gram. The waste mainly consists of contaminated protective clothing, rags, old tools and equipment, pieces of dismantled buildings, chemical residues, and scrap materials. The total activity of the waste expected to be disposed at the WIPP is estimated to be approximately 7 million curies, including 12,900 kilograms of plutonium distributed throughout the waste in very dilute form. The WIPP is located near the community of Carlsbad, in southeastern New Mexico. The geological setting is a 600-meter thick, 250 million-year-old saltbed, the Salado Formation, lying 660 meters below the surface.

The National Research Council (NRC) has been providing the U.S. Department of Energy (DOE) scientific and technical evaluations of the WIPP since 1978. The committee's task is twofold: (1) to identify technical issues that can be addressed to enhance confidence in the safe and long-term performance of the repository and (2) to identify opportunities for improving the National Transuranic (TRU) Program for waste management, especially with regard to the safety of workers and the public.

This is the first full NRC report issued following the certification of the facility by the U.S. Environmental Protection Agency (EPA) on May 18, 1998. An interim report was issued by the committee in April 2000 and is reproduced in this report. The main findings and recommendations from the interim report have been incorporated into the body of this report. The overarching finding and recommendation of this report is that the activity that would best enhance confidence in the safe and long-term performance of the repository is to monitor critical performance parameters during the long pre-closure phase of repository operations (35 to possibly 100 years). Indeed, in the first 50 to 100 years the rates of important processes such as salt creep, brine inflow (if any), and microbial activity are predicted to be the highest and will be less significant later. The committee recommends that the results of the on-site monitoring program be used to improve the performance assessment for recertification purposes. These results will determine whether the need for a new performance assessment is warranted. For the National TRU Program, the committee finds that the DOE is implementing many of the recommendations of its interim report. It is important that the DOE continue its efforts to improve the packaging, characterization, and transportation of the transuranic waste.

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