Yucca Mountain: Pro & Con

Is Nevada's ridge of volcanic rock our best hope for storing nuclear waste or the centerpiece of a public relations ploy?

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Taking the High Ground

By B. John Garrick
Fellow, American Nuclear Society

PRO

Years ago, before the accident at the Three Mile Island nuclear plant in Pennsylvania, antinuclear activists complained that there was no satisfactory method of permanently disposing of nuclear waste. Today, almost 25 years later, they're still upset. Only now, it's the possibility of permanent waste disposal that has them up in arms.

Lately the focus of their wrath has been the decision of the U.S. Congress to grant permission to the Department of Energy (DOE) to seek a license from the U.S. Nuclear Regulatory Commission (NRC) to build a repository for nuclear waste. The point merits elaboration: DOE does not yet have permission to build a repository. It would be a decade, at least, before the department could begin sequestering waste canisters there. This fact seems not to have registered with many of those who oppose the recent congressional decision. The repository would be built under Yucca Mountain in Nevada, where the DOE and its contractors have been conducting tests for more than 20 years.

Opponents have criticized the Yucca plan on several grounds. They say that the Yucca site is unsuitable because its geology could not possibly isolate nuclear waste for the thousands of years that the waste would be harmful. They say the DOE's analysis has been sloppy. They insist that a single underground repository is not needed, and that trucking the waste thousands of kilometers to the site of such a repository would present grave risks. They argue that Yucca is a public relations ploy designed to convince people that the nuclear waste problem is being solved.

I have studied all of these issues and more. My conclusion is that hardly any of these objections hold up to close scrutiny, and even those certainly do not justify halting the project.

Tuff stuff

First of all, why Yucca? There are several reasons. Yucca is relatively isolated from population centers. It is also right next to a de facto repository that for decades has contained countless millions and millions of curies of radioactivity without instability. It's called the Nevada Test Site, where the United States conducted scores of underground and other nuclear weapons tests from 1951 to 1992.

Perhaps most important, Yucca receives an average of only 15 cm of rainfall each year. This lack of precipitation is notable because the main function of the repository would be ensuring that water does not corrode the containers of waste and enable particles of that waste to migrate beyond the boundaries of the repository. In this context, it is significant that the valley below Yucca Mountain is a largely closed drainage system that prevents most water from moving far from the site.

Finally, Yucca Mountain is made up of a reconsolidated volcanic ash called tuff. This extremely stable rock could easily absorb, without cracking or crumbling, the heat that would be thrown off by the packages of high-level waste.

For the DOE, though, evidence of Yucca's present suitability won't suffice. Before it can get a license to build a repository at Yucca, it has to submit a detailed probabilistic risk assessment to show that the repository would not—for 10 000 years—expose populations to radiation levels beyond 0.15 millisievert per year. (For perspective, consider that a single transpolar flight exposes you to about 0.1 mSv.)

Years ago, the DOE strove to demonstrate that the site's geology and hydrology would be the primary factors in isolating the waste for at least 10 000 years. More recently, it has sought to show that a combination of natural setting (Yucca) and engineered systems (waste canisters and other structures) will do the job.

 

Critics have nevertheless gone on questioning whether the site's geology alone could isolate the waste for at least 10 000 years. This is the wrong question. A much better one is, can we find a safe, secure, and cost-effective way to isolate high-level nuclear waste from human life for at least 10 000 years? Our engineering capabilities have improved dramatically over the past 20 years. Today we can build protective barriers and waste packages that can come close to meeting the 10 000-year standard all by themselves. Why shouldn't we exploit this knowledge?

Obviously, the most prudent approach is to put the best engineered systems in a favorable setting. We call this defense-in-depth, and it has long been the hallmark of nuclear safety engineering.

None of this is to suggest that the DOE's work, and particularly its analysis, has been above reproach. In fact, the department has relied on assumptions that mask a realistic assessment of the risk. Some of its computer models, for example, rely on assumptions that are not supported by the available evidence. Another problem is that the DOE has sharply focused its analyses and models on meeting the regulations. A more reassuring approach would be to study the risks in a neutral way, unbiased by the regulations.

This problem, however, is one the NRC will have ample opportunity to rectify when it reviews the DOE's application for a license to build a repository at Yucca. And I have faith that the NRC will not flinch from its responsibility. The commission has already demanded that the license application for Yucca Mountain be "risk-informed." Congress wisely allowed the DOE to apply for the license; it is now up to the NRC to make sure the DOE performs a more comprehensive and realistic risk assessment than it has done so far.

Risks in perspective

Why go through all this effort and expense if, as opponents point out, there is no storage crisis today? Simply put, the waste-storage system we have today—a combination of cooling pools and large "dry" casks that sit at the reactor sites—requires active management and is in no way a permanent solution. About 40 000 tons of spent nuclear fuel are stored in pools at 110 operating and closed reactor sites across the United States, with 2000 more tons added each year. This storage is safe, well managed, and, relative to the electricity produced, inexpensive. It could probably be expanded indefinitely. Some of the older fuel rods, whose radioactivity and heat have been greatly reduced, are now being put into dry casks for storage at the nuclear power plant sites.

While these pools and casks keep the spent fuel safe, each of them must be monitored and guarded 24 hours a day. Many of the pools, which are in 34 states, are close to population centers and all depend on redundant electrical pumps and cooling systems.

Those pools, as well as the dry cask storage facilities, might also make a tempting target for terrorists. The risk of a terrorist strike on these sites is admittedly not that great. But it's greater than the risk would be at Yucca Mountain, where the waste would be hundreds of meters underground and where no unauthorized vehicle could approach without prompting a visit from a military helicopter.

Critics have also hypothesized all sorts of dangers involved in transporting the waste to the repository. In fact, the risks are close to zero. We have been moving radioactive waste all over the nation for over 50 years, and there have been no fatalities resulting from radiation exposure.

No form of power generation is risk free. There are risks associated with nuclear power plants, with the transportation of hazardous wastes, with the mining of uranium, and with the storage of hazardous wastes. There are also risks and health hazards connected to mining and burning coal, tapping and using natural gas, or building and operating hydroelectric dams. Hundreds, perhaps thousands, of people die each year in coal mines or from respiratory ailments linked to coal combustion.

 

If you calculate the number of fatalities worldwide associated with other generating options, as several organizations have done in recent years, you find that the number of deaths per gigawatt-year for hydroelectricity is 0.80, thanks to some catastrophic dam failures in India, Colombia, and Romania. For nuclear power the figure is 0.01. All of the nuclear-related deaths—31 of them—were of plant and emergency workers at the Chernobyl nuclear power plant in 1986.

A new mindset

As long as the focus is on burying high-level waste forever, without any possibility of even an infinitesimal leak, the nuclear industry will lose. That is an unachievable and ridiculous goal, and an unnecessary one.

We need to get rid of the permanent-disposal mindset. We don't use that philosophy with other wastes, and we shouldn't here. What we should do is put the waste in a place like Yucca Mountain, where we can keep an eye on it, and reclaim it if, centuries from now, we invent more expeditious technologies to dispose of it. Alternatively, we can close up the mountain if new knowledge, new generations of people, and new confidence make that a desirable thing to do.

That is not to say that Yucca Mountain doesn't need to do its job for 10 000 years. It should be built to do precisely that job, with no human intervention. But there's no reason why we shouldn't continue to monitor things.

Much of the outcry against Yucca Mountain has come from Nevada's residents and congressional representatives. They resent the idea of being the nation's nuclear dumping ground. They suspect that the barrenness of much of the state, and the relatively small size of its congressional delegation, have made it the jurisdiction least able to defend itself against a national high-level-waste repository. They're probably right.

This is a political problem, and there are positive ways of addressing it. Many places, including the entire country of Sweden, have learned to stop worrying and embrace nuclear power. Constellation Energy Group (Baltimore, Md.) a few years ago applied for renewal of its license to operate the Calvert Cliffs nuclear plant (Lusby, Md.). Huge throngs turned out in support, and Mary Krug, a former county commissioner, said the plant "had no local opposition."

It's not hard to see why. Calvert Cliffs employs 1200 people, three-quarters of whom live in Calvert County. The plant's operators donate millions of dollars to local charities. The plant also pays US $20 million a year in county property taxes. Not incidentally, the plant has performed extremely well and has demonstrated to its neighbors that it is environmentally clean and safe.

A repository at Yucca, employing hundreds of people for decades, could also improve the local economy. There's plenty of room for growth.

Some of my colleagues have shared with me in private their view that Nevadans do not resent the sprawling and cratered Nevada Test Site because it was a Nevada project from the beginning. Yucca, on the other hand, is something foisted upon them by Washington. There is no getting around that. But in making the best of this situation, they would be doing their country—and maybe even themselves—a great service.

 

Burying Nuclear Power

By Victor Gilinsky
Former Commissioner, U.S. Nuclear Regulatory Commission

CON

Burying nuclear waste deep beneath Yucca Mountain in Nevada, as the U.S. Department of Energy proposes to do, is neither an urgent necessity nor a rational, long-term solution to the problem of nuclear waste. The real point of this plan is to enhance the current prospects of nuclear energy by giving the impression that the nuclear waste problem has been "solved" once and for all. It has become a kind of giant entitlement program that will ensure outsize budgets—and controversy—for the Department of Energy (DOE) and its contractors for many decades to come.

This ill-advised endeavor got a major boost this past July, when the U.S. Senate voted to support President George W. Bush's earlier recommendation of the repository site. The House of Representatives had voted its approval earlier, in May.

The tallies cleared the way for the DOE to file for a construction permit from the U.S. Nuclear Regulatory Commission (NRC). By law, the DOE must do this by 23 October. But it doesn't have its act together and admits it won't be able to file before December 2004.

So far, the DOE and its contractors have dug a 7.6-meter-wide U-shaped tunnel into the mountain. This 8-km loop is being used for studies of the site; it would also be the main access tunnel of a future repository. The idea is to package the waste—mostly power-reactor spent-fuel assemblies about 4 meters long and half a metric ton each—in metal canisters. These would be loaded into passages sprouting off the main tunnel, some 300 meters below the top of the mountain and about 300 meters above the groundwater at the site.

"Studied to death?"

The DOE has spent US $7 billion and 20 years studying Yucca Mountain. Nevertheless, it has not even made the most basic design decision: whether the repository will be hot or cool, a decision fundamental to controlling water corrosion of the canisters containing radioactive waste. Water not only corrodes the canisters; it would also convey loose waste particles outside the repository, where they could harm people.

In a so-called hot repository, the canisters are packed so closely that the temperature around them rises well above the boiling point of water, which is then expelled, in theory, anyway. The trouble is that at high temperatures corrosion rates are higher, too. The performance of a cool repository would be more predictable, but it would be much larger and would also require waste to cool on the surface for decades before it could be placed underground.

The DOE has favored the hot repository idea, but hasn't won over its scientific overseers. A few years ago, attempting to prove the concept, the DOE installed heaters in underground chambers to simulate the hot fuel. I toured Yucca Mountain not long after, in May 2000. As I stood looking at the tunnel ceiling, I was surprised when water dripped down on my face. The heaters had driven water vapor out of the immediate area, but it condensed when it hit cooler rock and dripped down—not a good omen.

The bottom line is that the DOE has not satisfactorily dealt with the water problems and their interaction with heat from radioactive spent fuel. Acknowledging that heat probably will not be enough to keep water away from the waste canisters, the DOE now says it will protect each one with a titanium drip shield. These big umbrellas will add an estimated $4 billion to the repository cost.

 

This engineering patch is yet another example of how the DOE continues to re-tailor its rationales to keep the project going in the face of obvious deficiencies. From 1984 until the mid-1990s, the department insisted that it would approve or reject the site primarily on the ability of its geology to isolate the waste. "Primarily" is exactly what the law requires. But when the DOE's tests found problems, including much more water than expected, it backed away from that promise. Last December the DOE dropped its geological criteria and adopted a different, and much weaker, standard. This only requires that the site be deemed capable of meeting the NRC's licensing rule, which has no separate requirements for geologic waste isolation. It simply requires that people living near the repository not be exposed to radiation levels beyond a certain limit for 10 000 years.

yuc02.jpgIn other words, the site geology does not matter if the DOE can convince NRC, as it plans to do, that its canister—made of Alloy 22, a nickel-chromium-molybdenum alloy—can last 10 000 years. But if the canister is so good, why choose a deep underground storage site thousands of kilometers away from most of the reactors that produce the waste? Not surprisingly, Nevada is contesting the change in tactic in federal court.

Aside from the law, does a separate geologic requirement really matter, so long as people are protected for the foreseeable future? Yes, because the assurance of protection in this case hinges on an extreme extrapolation from a limited database on the performance of materials and systems. The new standard lets the DOE put all the different factors—such as the characteristics of the canisters and the site's geology—into a computer model that estimates ground radiation doses 10 000 years into the future. That may sound impressive. In reality, because of the enormous complexities of the model, the uncertainty of the inputs, and the many arbitrary assumptions, it has been a recipe for masking problems.

"Masking" is precisely the word used by the NRC's own Advisory Committee on Nuclear Waste, in a 2001 report on the DOE's Total System Performance Assess-ment-Site Recommendation (TSPA-SR): "The masking of realism in the TSPA-SR precludes providing a clear basis to estimate the margins of safety, or making an objective regulatory decision that is in the best public interest."

The Nuclear Waste Technical Review Board, an independent scientific agency created by Congress in 1987, had serious concerns about the DOE's near-total reliance on the canisters to pass the NRC's licensing standard. In January 2002, the review board pointed out that "data on aqueous corrosion for Alloy 22 above about 120 C under conditions relevant to Yucca Mountain are essentially nonexistent."

As one of the board members said earlier, "We are betting the performance of the systems on the long-term performance of these effectively new materials." In an April 2002 report, the board reviewed the technical underpinnings of DOE's repository performance estimates and characterized them as "weak to moderate," hardly a vote of confidence.

Uninspiring behavior

Once canisters containing tons of radioactive waste are permanently buried in underground tunnels, we won't be able to make up for serious miscalculations or erroneous assumptions. What's more, the safety issues are complex and inevitably involve some degree of judgment. In the final analysis, a lot depends on the competence and sense of public responsibility of the DOE and its contractors.

Here, unfortunately, DOE's performance over the past couple of decades does little to inspire confidence. It has struggled for years with its own waste sites. At Hanford, Wash., for example, it has spent about $5 billion on waste-related work, with discouraging results [see "Money for Nothing," IEEE Spectrum, July 2002, p. 12].

 

Lately, in the face of intense scientific criticism, the department has invoked national security arguments to defend Yucca Mountain. The most egregious of these preys upon public fears, in the wake of the 9/11 attacks, that terrorists might attack the hundred or so reactor spent-fuel pools where irradiated fuel cools, or the so-called dry casks in which it is subsequently stored. The department cultivated the public impression that if Yucca Mountain were approved, it would promptly collect spent fuel from the reactor sites and lock it away deep underground.

The truth is that it would take the DOE several decades to collect the spent fuel and salt it away underground. In any case, since spent fuel has to cool at the reactor site for at least several years, there will be spent-fuel storage at reactor sites so long as there are operating power reactors. Naturally, these NRC-licensed sites are heavily protected.

Strip away all the rhetoric and slanted studies, and it becomes clear that the Yucca Mountain project has little to do with public safety, or security, or even the lack of storage capacity at power reactor sites. It has to do with the nuclear industry's idea of how to rectify public "perceptions." Consider this bit of testimony before the U.S. Senate in 1981 by Sherwood H. Smith, a top nuclear utility official speaking for the industry as a whole:

"The reasons why the utilities have consistently urged the Federal Government to implement promptly a waste management program are principally neither economic nor technical....Both spent fuel and vitrified high-level wastes can be stored for centuries safely in above-ground orsub-surface 'temporary'storage.... Despite this, however, the public equates the absence of a disposal facility with the absence of a solution to the nuclear waste management 'problem'....The best way to change this perception is to have one acceptable permanent waste management facility in being. Once the public can see a geological repository under way, we believe this perception will change."

A billion dollars per reactor?

The problem is that the estimated cost of this exercise in public relations has increased wildly from about $1 billion to something in excess of $60 billion, according to the DOE's latest projection, and is likely to grow to $100 billion, in my view. That's about a billion dollars per power reactor, or over $1000 per U.S. family. It is a funding dream for the DOE and its contractors, but not for you and me.

Proponents seem unwilling to grasp that Yucca Mountain is not needed to continue, or even expand, nuclear power use. There is ample opportunity to expand NRC-approved dry-cask storage at reactor sites. Eventually, these casks should be collected at dedicated near-surface storage locations where we can monitor the casks' integrity. The important thing is that there be sufficient time to do a responsible job in terms of safety and security, and at far lower cost than we would pay at Yucca Mountain.

Yucca Mountain isn't the answer to our spent-fuel worries. But now that Congress has given the DOE a green light, events will have to run their contentious course in the federal courts and at the NRC before the nation gets it right. Ironically, the coming struggle is likely to damage rather than enhance the prospects of nuclear energy.

About the Authors

B. JOHN GARRICK an independent consultant living in Laguna Beach, Calif., helped pioneer probabilistic risk assessment. He is a fellow of the American Nuclear Society and a member of the National Academy of Engineering, which bestowed on him its highest honor, the Distinguished Achievement Award, in 1994.

VICTOR GILINSKY is an energy consultant in Washington, D.C., and a former commissioner of the U.S. Nuclear Regulatory Commission. He has been a consultant to the state of Nevada on issues related to Yucca Mountain.

To Probe Further

Disposition of High-Level Waste and Spent Nuclear Fuel: The Continuing Societal and Technical Challenges was published last year by the National Research Council, Washington, D.C. The 198-page book includes detailed discussions of waste-disposal concepts and plans in 14 countries.

The Department of Energy maintains a Yucca Mountain Project home page at http://www.ymp.gov/. The State of Nevada, which opposes construction of the repository, has its own page at http://www.state.nv.us/nucwaste/.

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