According to a ruling earlier this summer, the Environmental Protection Agency's 10,000-year radiation safety standard for the proposed Yucca Mountain nuclear waste repository in Nevada is too short-sighted.
So said a federal court in July that ruled that EPA's rules must be "consistent" with a 1995 report authored by a committee at the National Academy of Sciences (NAS). The scientists found that peak radiation levels at the site will not occur for up to a million years, and they recommended that the repository be built to last at least that long.
The decision leaves the Yucca Mountain project in legal limbo. And it places the committee that authored the NAS report in the awkward role of de facto policy-maker.
"The real problem is that the whole scenario is wrong," said Robert Fri, Ph.D., a scholar at the environmental think tank Resources for the Future, who chaired the report committee. "Setting a standard and measuring compliance is fine in the short-term. It's measurable. We should be asking, `What stewardship plan minimizes risk over two or three generations?'" Setting standards based on geological time scales "is not a particularly constructive way to go."
But that is how the Energy Policy Act of 1992 is written. While the NAS normally serves the government in a strictly advisory role, intense political wrangling over plans for the nation's first "permanent" radioactive dump led to a legislative oddity: EPA had to do more than simply listen to the NAS. It had to "promulgate standards consistent with the findings and recommendations of the [NAS]."
"It's a scientific trap," said physicist Richard Meserve, Ph.D., president of the Carnegie Institution and chair of the NAS's current Board on Radioactive Waste, which convened in September to mull over the ruling. "Something that might or might not happen hundreds of thousands of years in the future is driving policy decisions today."
In the meantime, most of the nation's 40,000 tons of spent fuel rods sit in 141 cooling pools never intended for long-term use. Vulnerable to leaks, accidents, and sabotage, the concrete ponds sit near nuclear plants in 39 states, many within a few dozen miles of large cities.
Simulated Leakage
Until the mid-1990s, Yucca Mountain was considered geologically ideal as a nuclear waste site. It is arid, desolate, volcanically inert, and not prone to earthquakes. But concerns about its suitability surfaced in the mid-1990s, when Department of Energy (DOE) scientists found that groundwater was leeching into the rock much faster than expected. So in a Las Vegas strip mall 90 miles southeast of the half-built dump, the DOE's Yucca Mountain Field Office began running sophisticated simulations on dozens of computers. They quickly discovered that simulating geological features in all their structural, chemical, thermal, seismic, and tectonic complexity is a slippery task.
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"The longer the model, the more uncertain the results. A small change in input ends up causing large changes in the output," said Meserve. In other words, the ravages of time exponentially amplify uncertainties.
The DOE recruited an army of experts from a dozen fields to squeeze all possible uncertainty out of the models. They developed formulas to express the probability that a given set of conditions would cause the mountain to leak within a given amount of time. The latest DOE rainwater simulation, for instance, shows that it will take about 80,000 years for the waste canisters to rust through. As millennia tick past, the containers will begin to corrode. They will eventually develop gaping holes.
Within the 10,000-year threshold, the DOE's virtual mountain performs brilliantly in thousands of hypothetical situations, always coming out below the limits set for radiation exposure.
But no simulation exactly matches reality. For an added level of insurance against the vagaries of geologic extrapolation, the DOE designed an "engineered barrier" consisting of rust-resistant canisters augmented with titanium drip shields to keep water away. The canisters would be made of Alloy 22, a blend of chromium, nickel, and other metals impervious to corrosionbut nobody really knows for how long. The alloy was first made in 1987.
The barrier does not satisfy opponents. "As a matter of generational equity, [the government] shouldn't build a repository that will fail at the end of its engineered life," said Joe Egan, Ph.D., former nuclear scientist and attorney for Nevada who heads up the state's many legal actions geared at relocating the nuclear waste repository.
The most serious challenge to the DOE's simulation and the NAS report's conclusions, though, is the one factor computers cannot modelhuman behavior. There is simply no way to predict how the population and landscape of Nevada will change in 100let alone 10,000years.
Fri noted that this is indeed true. "We just assumed the population you have today will be the population you have in the future. I mean, you just can't predict. If you start making up populations, you can pick a single scenario that solves all of the [regulatory] problems."
20 Years of Yucca
Today's regulatory problem began in the 1980s, when Congress began pondering a permanent repository site. Nine areas in six states were ostensibly being considered for the dump. But as the millennium closed, the EPA and DOE continually narrowed their focus to Yucca.
To allay the fears of environmental activists, Congress split responsibility for the dump among three agencies: The EPA would set standards, the Nuclear Regulatory Commission (NRC) would evaluate whether those standards had been met, and the DOE would build and manage the site.
Then in 1992, Congress broke with a 100-year tradition and penned the legislation elevating NAS from adviser to policy-maker. Nevada residents and officials, along with environmental activists opposed to the dump, reminded legislators that, in the 1950s, they had been assured nuclear weapons tests in their state would be nothing more than an "inconvenience." In fact, exhaustive research by National Cancer Institute epidemiologists estimates that the tests caused 15,000 cancer-related deaths and 20,000 nonfatal cancers. Congress agreed to force EPA to comply with independent risk estimates. The EPA contracted the job to the NAS.
A decade later, the Bush administration signed legislation formally establishing Yucca Mountain as the nation's first "permanent" nuclear repository. Schedules were drafted, tunnels were dug, and after two decades, $5 billion, and an enormous amount of debate, a plan to deal with the nation's radioactive waste was finally set in stone. In this case, a desert ridge some 100 miles northwest of Las Vegas.
But earlier this summer, in a response to a lawsuit against the EPA brought by several groups, a three-judge federal panel brought the plan to a halt.
In their scathing July ruling, the panel wrote, "Only in a world where `based upon' means `in disregard of' and `consistent with' means `inconsistent with' could EPA's adoption of a 10,000 year compliance standard be considered permissible" under the 1992 law.
But the court also ruled that, other than the time frame, the EPA's proposed standard was sound. The limit for exposureno more than 15 millirems of radiation per year for each nearby residentwas 333 times lower than occupational limits set for nuclear plant workers. Fifteen millirems is, in fact, about half the dose the average earth-dweller absorbs from cosmic rays each year and only about 5% of the average annual radiation exposure from all sources.
Boring Ahead
In September, the Nuclear Energy Institute (NEI), an industry lobbying group named as one of the defendants in the federal case, appealed to the Supreme Court. The NEI argued that the effort to build a repository for the nation's spent radioactive material is important enough to merit the attention of the highest court.
Officals with DOE and EPA declined to join the appeal. Jeffrey Holmstead, Ph.D., head of the EPA office charged with developing the standard, said that the agency would instead explore "ways to make the standard agree with the court ruling." He declined to elaborate, but he argued that the federal court ruling, interpreted absolutely literally, would force the agency into the absurd position of authoring a standard that ensures safety at Yucca Mountain for the rest of eternity. (The NAS report's executive summary states "there is no scientific basis for limiting the time period of the individual risk standard to 10,000 years or any other value.")
In any case, the agency is also going ahead with its plan to apply for the license needed to build the repository. The EPA and DOE say they will submit millions of pages of environmental studies and design evaluations to the NRC by the end of the year. The NRC's review is expected to take at least 3 years. Congress has set a deadline of 2010 for an operational site.
In the meantime, the Bush administration is pushing Congress to find a legislative remedy. Sam Fowler, a Congressional staff member who has served on the Senate Committee on Energy and Natural Resources during the entire Yucca affair, said that the leading proposal would reclassify high-level nuclear waste as lower-level waste, allowing it to remain indefinitely in the temporary cooling ponds. "Congress has some sympathy to relieving EPA of the NAS standards," he told the crowd at the NAS meeting. "The [1992 law] was wrong in putting the NAS in the position of policy-maker. But the public reaction would be that Congress is simply dumbing down health standards by reshaping the pattern to fit the cloth."
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Wrong Question
As the NAS meeting wound down, Fowler asked the current NAS Board on Radioactive Waste Management if they still stood by the "million-year standard" from the 1995 report. Meserve, the board's chair, replied that NAS "is not in a position to re-evaluate the 1995 report," because none of that report's authors serve on the current board.
As for the scientists who find themselves responsible, 9 years after the fact, for halting a $60 billion, 20-year project, Fri related a story from 1995 that he said is even more relevant today. After hearing about the report's conclusions, a senator invited Fri to Capitol Hill. "I told him, `There are a lot of uncertainties and it may be that the highest [safety] standard precludes even the best engineering.' After a tirade that I can't in good conscience relate in mixed company, I said, `Senator, you have the best scientific answer to your question. But you asked the wrong question.'"
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