Darrin Santos

Environmental Geology Seminar

Topic: The Disposal of High-Level Nuclear Waste.

The United States high-level nuclear waste (HLNW) program has been destined for failure since Congress decided to cut funding for research for other waste disposal sites and methods (land-based, sub-seabed or other) and run with the land-based Yucca Mountain repository as the sole "solution". Moreover, because of surmounting problems in the geologic setting at Yucca Mountain and having no "back-up" repository, Congress decided to start redefining rules, regulations, and standards originally set in place to ensure human and environmental safety. These policy changes, based on legislation rather than scientific inquiry, have led to public distrust of the Department of Energy (DOE): the agency in charge of developing and running a HLNW repository. The authors believe that the Yucca Mountain site is destined to remain the only possible site considered by the DOE until the current HLNW program is scrapped entirely and re-created with new core values. The new program should include scientific research, public regulatory input, and firm social, political, and technical consensus.

This paper is a policy review, which provides a detailed explanation of the problems and issues associated with the United States current HLNW program. The authors first explain how and why the current program is failed and then provide logical explanations for initiating and operating a new program. They certainly convinced me that the current HLNW program is failed and needs to be reworked. I believe (as well as the authors) that no HLNW site will be acceptable to the public until trust is established. Trust will be established through a scientific research/inquiry process where the public is well informed of each finding, negative or positive. I also like the authors suggestion that no state or community should be forced to accept all the nation’s waste against their will.

Nadis, S., 1996, The sub-seabed solution. The Atlantic Monthly, v. 278, n. 4, p. 28-39.

An area in the Pacific Ocean, 600 miles north of Hawaii and the 4 times the size of Texas, may hold the solution to the United States and the Worlds HLNW problem. The clay sediments on the bottom of the ocean have been tranquil for 65 million years and little can be done to stir those sediments to the biosphere. The idea is to encase HLNW and simply bury it ten meters below the ocean floor. All scientific research and evidence to date (including work conducted on sunken nuclear submarines) reveals absolutely no impact to natural systems due to the release of radioactive wastes in the clay sediments. The waste, when released, clings to the clay particles where it remains for thousands (possibly hundreds of thousands) of years. However, as easy as this solution may sound, and despite major scientific support, all sub-seabed research was nixed when Congress decided to "put all their eggs in one basket" and run with the land-based Yucca Mountain repository. Charles Holister, the chief scientist once in charge of the sub-sea bed research, believes additional scientific scrutiny is needed and should be conducted before sub-seabed dumping occurs. However, he has offered an estimate of $250 million in order to complete all necessary research: a figure that equals the budget for two weeks of the current failing nuclear clean-up and waste-disposal operations.

This paper, although not heavily referenced (Atlantic Monthly is not a peer-reviewed science journal), offers the best solution I have heard for the long-term disposal of HLNW. It is saddening to think that only "pocket change" is needed in order to complete the necessary research (which to date has offered no major negative findings or obstacles) to ensure the sub-sea bed solution is valid. As Holister says, "We still haven’t figured out as a society how to make decisions about high-level radioactive wastes." I think this paper is a perfect complement to Flynn et al.’s argument ("Over Coming Tunnel Vision…") that the current U.S. HLNW program is failed and needs to be totally recreated. Programs researching other places than Yucca Mountain that use scientific inquiry, like the sub-sea bed program, need to reinstated in order to find an acceptable answer to the world’s nuclear waste problem.

In the long and failed history of the United States nuclear waste disposal program, there is one success story: the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. WIPP, unlike Yucca Mountain, is a nuclear waste repository chosen by scientists not Congressional decree. The involvement of scientific inquiry (via an independent advisory board) and the constant disclosure of experimental results to the public (good and bad) have allowed WIPP to develop into the first site able to except bomb-related nuclear wastes (awaiting the settlements of current lawsuits). The land-based repository is located in deep (300 m) salt-beds that have been undisturbed for 250 million years. Scientists believe that the salt is an ideal medium in which to store the nuclear wastes. Any fractures and faults in the salt are quickly resealed as the salt easily "flows". However, problems including heat associated with HLNW, the highly porous nature of the salt, and pockets of pressurized brine have forced Congress to allow only lower-level transuranic wastes like those associated with bomb making to be disposed of at WIPP.

This is a short "News Focus" paper. The author does a good job of explaining how the involvement of an independent scientific advisory board helped WIPP develop into an "acceptable" nuclear waste storage site. The site will not accept HLNW, but I believe the process used to research and develop WIPP should be implemented on Yucca Mountain (and other HLNW sites). Some issues that the author did not resolve are that the site does have pockets of pressurized brine, salt-water oozes from walls in the facility, and long term problems associated with climate change (like its affect on surface permeability). Even though WIPP is a lower-level nuclear waste site, the author did not entirely convince me that it is safe for long-term disposal.

Sheppard et al. use a model to assess the effects of continental glaciation on radionuclide release and transport to the biosphere from a nuclear waste vault mined in stable plutonic rock of the Canadian Shield. Eventually the geologic and man-made barriers of the vault will be compromised and radionuclides will be carried by groundwater to the biosphere. The authors utilize the BIOTRAC (BIOsphere TRAnsport and Consequence) model to integrate four separate submodels including surface water, soil, atmosphere, and food-chain to evaluate nuclide dose increases to populations via mass balance transfers. The authors conclude that the ecosystem change brought by continental glaciation will far outweigh any damages caused by increases in radionuclides originating from the vault in the Canadian Shield. The results of the model indicate that the interglacial and cold interstadial states will likely result in the release of similar total doses of nuclides. The glaciated area will receive the highest doses of nuclides, but due to the large release of melt-water those doses will be significantly diluted. Also, humans are assumed not to inhabit the glaciated regions placing them far away from any significant nuclide release.

This paper is very readable and the figures complement the text well. I enjoyed the problem of continental glaciation, which the paper seeks to address. This is a problem, which will undoubtedly affect any geologic nuclear waste repository in northern regions. Most papers I read for this topic deal with short-term problems in storing nuclear waste, but nuclear waste is inherently a long-term problem. The model the authors present is like all models and can not address every single parameter associated with the each system. I think the weak part to their study is that, rather than determining actual quantitative values for increases in dose to various populations, they just conclude that interglacial and cold interstadial events will result in similar total doses that are not harmful to humans.

Bird and Fyfe give an overview of the necessary properties of a geologic waste repository. In introducing these necessities they also report on the current lack of knowledge and the potential feasibility of a geologic repository. They offer some guidance in the form of what type of research is needed that will offer answers to the unknowns of a geologic repository. An ideal geologic repository will consist of several compartments or barriers. First, the actual waste itself will be solidified in a glass-like substance and placed in a durable sealed (waterproof and corrosion-proof) container. A buffer material capable of both impeding groundwater flow and any potential release of waste will surround the container. Some type of backfill material will cover the buffer and container. This whole containment system will be located at a depth of 1 km or more below the surface in a massive crystalline rock formation. The rock formation ideally will be void of fractures and groundwater. There are areas of uncertainty in the repository where research is necessary. 1) The effects of elevated temperature and hydrothermal alteration (due to decaying waste) on the surrounding rock and containment materials including the glass, container, buffer, and backfill. 2) The effects of the introduction of water, especially salty water, in the containment area. 3) The permeability of rocks at depths greater than 1 km. 4) Rock fracturing mechanisms at depths greater than 1 km. 5) The retrievability of the wastes should problems occur.

Bird and Fyfe provide an interesting and rather simple approach to explaining what is necessary for a geologic repository. I like that they do mention that a lot of research is necessary in order to fully explain what will happen in and around a repository mined in a deep rock formation. The authors seem optimistic that a geologic repository will work even though they mention many necessary experiments that may not yield the results their expecting. I believe the repository the authors describe will work if all ideal circumstances are fulfilled. However, I can not believe that these ideal conditions could all be met.

Although titled "Long term waste problems from electrical production" this paper is a comparison of the risks to humans from high-level nuclear waste, uranium mining, chemical carcinogens from burning coal, and chemical carcinogens from photovoltaic cells (used for solar energy production). Results of calculations suggest that (for time periods integrated over millions of years and/or 500 years) waste from nuclear power (stored in geologic repositories) will cause thousands of fewer deaths (per GW [electric]-yr) than do the wastes from coal burning and photovoltaic electrical generation. Mining uranium for nuclear fuel (by reducing future radon exposures) actually saves hundreds of times as many lives as will be lost from nuclear wastes. All calculations are based on a linear-no threshold dose-response assuming ingestion as the main route of entry for all hazards.

The paper is mildly difficult to follow because it is loaded with equations and calculations in the text. It is certainly readable, but having the calculations in the text, I believe, makes the paper less effective. Cohen offers some interesting conclusions that seem to make the deaths due to nuclear waste minimal in comparison to hazards associated with coal and photovoltaic electrical energy generation. Another interesting conclusion is that the mining of uranium for nuclear energy will save hundreds of lives per year by reducing the amount of radon available to cause harm to humans. These conclusions have to be taken ‘at face value’ though. All of the conclusions are based on calculations that make broad generalizations of real world situations. Since all systems and situations can not be exactly quantified, there could be major errors associated with some or all of the numbers/equations used in this paper. I would have liked to see a section of possible errors in the calculations and a range of values incorporating these errors into each value obtained.

Cohen suggests that a "clear demonstration" is necessary in order to find an acceptable method for disposing of nuclear waste. This paper offers a demonstration of ocean dumping as an acceptable method. The ocean floor is a uniform, stable, and predictable environment (in this case storage containers would be placed on the ocean bottom surface, not buried in the sediments). An advantage of ocean dumping, over burial in rock formations, is improved capability to retrieve, access, and monitor the wastes. The wastes would be encased in glass that would ensure a 30,000-year time period before the waste would be released to the environment. Taken this time period into account, there would be 0.17 eventual human fatalities per GW(electric)-yr. By ignoring this time frame (i.e. immediate release of waste to the environment) this figure would increase by 30%. This figure is 150 times less than the fatalities due to wastes produced by coal-fired electric plants. Effects on ocean ecology are also offered; the radiation dose to marine life will not be higher than 1% of the exposure from natural radiation.

The paper, much like the other by Cohen ("Long term waste management…"), contains some interesting conclusions concerning the effects of nuclear waste to human life when released into the environment (in this paper, the ocean environment). This paper does contain some interesting support for the ocean dumping solution. The increased accessibility to the waste and the elimination of the psychological problem associated with having one geographic region accept all of the nation’s wastes are certainly large problems in the nuclear waste issue. Also, the excellent heat transfer capacity of water will help in reducing temperatures associated with nuclear decay. The figures for deaths due to nuclear waste and effects to ocean ecology have to be ‘taken at face value’, since the calculations used to derive these figures have made very general assumptions about complex systems. I believe one weak portion of the paper is how Cohen assumes that the method of glass encasement of the waste will ensure a 30,000 year period before the waste will be released (figure derived by assuming the ocean water will take 30,000 years to dissolve the glass and thereby release the waste). What happens if the glass surrounding the waste simply cracks? All other sources (dated after this paper) I have read refer to the current lack of knowledge in the technology of encasing the waste in glass, especially when introduced to high temperatures.