WIPP- Whats Wrong With Burying Waste In The Region?

Hot Brine Moves Toward Hot Waste
The temperature within the repository may reach 300°C. Water, in the form of liquid and vapor is drawn towards the heat source in a salt repository, as opposed to other geologic medium where water moves away from the heat source. This hot brine solution is acidic and very corrosive. According to the EPA (p. 7), the canisters would be breached in a decade or less. Under these conditions, only the geologic medium can be relied on to affect any significant retardation for times longer than a decade. Surprisingly, no corrosion tests have yet been undertaken of containers exposed for decades to salt solutions, at temperatures up to 300°C, (EPA, p. 20).

Repository Will Weaken
The presence of brine and increased temperatures would undermine the structural integrity of the salt repository. According to the USGS (p. 6), "Increased temperatures in salt would further decrease mechanical strength of the salt-brine mixture and would increase the creep rate of dry salt."

Difficult To Retrieve Wastes
The movement of salt under increased temperatures means that it would be almost impossible to keep the repository open for extended periods of time. According to the EPA (p. 3), it is unlikely that spent fuel rods could be safely recovered from a salt repository "more than a few tens of years after emplacement and backfilling, for by then the salt would have completely sealed the openings." Thus salt is not the medium if retrievability is desired.

Hot Wastes Will Sink
As the salt is heated and becomes more plastic, it is expected that the canisters would begin to sink (USGS, P. 17). Simultaneously, the canisters will corrode and leach. As the canisters move downward, the canisters would also move laterally towards the center of the repository where the temperatures are greater compared to the outer extent of the repository. As the canisters moved towards each other, the center would become still hotter and the salt more plastic. As the salt becomes more plastic, the structural integrity of the repository would be further reduced. Most salt formations overlie permeable limestone formations. The canisters could thereby move downward to the limestone formation and enter the ground water movement.

Salt Will Not Work
Salt should not be considered the preferred medium. Salt is extremely water soluble, is highly corrosive, and does not hold the radionuclides effectively. I~hen salt is heated, water is attracted to the heat sources, such as canisters of radioactive waste. Water moving through the salt becomes brine. When this brine reaches the radioactive waste materials, the glass or ceramic waste forms will break down and the radioactive materials will leach out. It has only recently been recognized that this leaching can occur in months, rather than thousands of years, as had been previously assumed.

Salt Is Corrosive
Two high level waste forms would be placed within a geologic repository, spent fuel or the high level waste from reprocessing. If spent fuel is reprocessed, the favored waste form would be glass. In the presence of steam, salt and acid, the glass would "deteriorate rather completely... in a matter of days." (NAS, p. 116)

Transportation Is Risky
Transportation of radioactive wastes into the populous parts of the U.S. and foreign countries maximizes the risk to the population. During transportation, the wastes are closer to larger numbers of people and "risks of accidental dispersal of radioactive material are greater than during either processing or emplacement" (NAS, p. 30).

REFERENCES
EPA, "The State of Geological Knowledge Regarding Potential Transport of High-Level Radioactive Waste From Deep Continental Repositories", Office of Radiation Programs, Environmental Protection Agency, EPA/520/4-78-004, June, 1978.

NAS, "Solidification of High-Level Radioactive Wastes", Panel on Waste Solidification, The National Research Council/National Academy of Sciences, prepublication copy

USGS, "Geologic Disposal of High-Level Radioactive Wastes - Earth Sciences Perspectives", U.S. Geological Survey Circular 779, by J.D. Bredehoeft, et al