High-level waste proposed repository

Fig. 6. The Nagra/PSI TDB 01/01 was used in this modelling chain for the performance assessment of a proposed Swiss repository for spent fuel, vitrified high-level waste, and long-lived intermediate-level waste.

Requirements for Disposal and Their Relationship to Waste Classification. Under current laws and regulations, spent fuel, high-level waste, transuranic waste, and low-level waste generally do not require particular disposal systems. However, only certain types of disposal systems are authorized for some types of waste (see Table 4.1). In particular (1) spent fuel, high-level waste, transuranic waste, and greater-than-Class-C low-level waste normally are intended for disposal in a geologic repository, such as the proposed Yucca Mountain facility and the Waste Isolation Pilot Plant and... 

Transuranic Waste. It has been proposed that in the future the transuranic (plutonium-containing) wastes be placed in deep mined vaults. This includes the high-level nuclear wastes. The vaults are expected to be about 1000 meters below the earth s surface and will be backfilled and sealed as they are filled. It appears that the repository capacity for high-level wastes will be heat-limited to one kilowatt/acre. This is equivalent to one ton of fuel after storage for ten years. The spent fuel discharged by the year 2000 will require about 2700 subterranean acres. This would... 

Pearcy, E. C., Prokryl, J. D., Murphy, W. M. Leslie, B. W. 1994. Alteration of uraninite from the Nopal I deposit, Pena Blanca District, Chihuahua, Mexico, compared to degradation of SNF in the proposed U.S. high level nuclear waste repository at Yucca Mountain, Nevada. Applied Geochemistry, 9, 713—732. 

NRC (2001). U.S. Nuclear Regulatory Commission. 10 CFR Part 63—Disposal of high-level radioactive wastes in a proposed geologic repository at Yucca Mountain, Nevada, Final rule, 66 FR 55732 (U.S. Government Printing Office, Washington). 

The groundwater transport of radionuclides through waterbearing interbed layers in the Columbia River basalt formation will be controlled by reactions of the radionuclides with groundwater and interbed solids. These interactions must be understood to predict possible migration of radionuclides from a proposed radioactive waste repository in basalt. Precipitation and sorption on interbed solids are the principle reactions that retard radionuclide movement in the interbeds. The objective of the work described herein was to determine the sorption and desorption behavior of radionuclides important to safety assessment of a high-level radioactive waste repository in Columbia River basalt. The effects of groundwater composition, redox potential, radionuclide concentration, and temperature on these reactions were determined. 

Introduction actinide solubilities in reference waters. In this section, the environmental chemistry of the actinides is examined in more detail by considering three different geochemical environments. Compositions of groundwater from these environments are described in Tables 5 and 6. These include (i) low-ionic-strength reducing waters from crystalline rocks at nuclear waste research sites in Sweden (ii) oxic water from the J-13 well at Yucca Mountain, Nevada, the site of a proposed repository for high-level nuclear waste in tuffaceous rocks and (iii) reference brines associated with the WIPP, a repository for TRU in... 

US Nuclear Regulatory Commission (2001) 10 CFR Parts 2, 19, 20, 21, etc. disposal of high-level radioactive wastes in a proposed geological repository at Yucca Mountain, Nevada final rule. Federal Register 66(213), 55732-55816. 

Figure 1.1. Yucca Mountain, in southern Nevada, is the only proposed geological repository site for high-level nuclear waste in the USA. Photograph courtesy of Neil Coleman of US Nuclear Regulatory Commission.

One of EPA s responsibilities has been to develop public health and safety standards for the two major U.S. nuclear waste storage and disposal facilities. The Wa.ste Isolation Pilot Plant in New Mexico stores transuranic wastes. They range from slightly contaminated clothing to barrels of waste so radioactive that it can only be handled with remote control equipment. The proposed Yucca Mountain repository is designed to store high-level radioactive waste and spent nuclear fuel. 

After the fuel is irradiated in the reactor, there are two divergent paths proposed to handle the used fuel. The first is to package it and dispose of it in a geologic repository as high-level nuclear waste. The alternative is to reprocess it to extract the remaining uranium and also recover the plutonium that was produced during irradiation. The waste from this process is the fission products. As seen in Chapter 14, there are several processes that can be used to preserve the useful uranium and plutonium. 

Sorption in the geosphere may help to mitigate radionuclide transport from the proposed high-level radioactive waste repository at Yucca Mountain, Nevada. Probabilistic performance assessment (PA) models typically use a constant sorption coefficient (K ) for each radionuclide and each hydrostratigraphic unit. Approaches have been developed that include aspects of mechanistic sorption models into PA calculations. Simplified surface complexa-tion models are calibrated against laboratory experiments and used to calculate actinide transport parameters. In one approach, parameter distributions are calculated based on site-specific water chemistry from the Yucca Mountain vicinity. Model results are used to provide limits on probability distribution functions as input into PA. Under the groundwater chem-... 

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