RELATIVE RISKS

In a rational world, humans would determine their actions by an objective analysis of risks. In the case of Yucca Mountain, an entire new field of science, i.e. nuclear risk perception analysis, has arisen to try and prove the opposite, that perceived risks should be the determining factor behind technological advance. In the preceeding chapters, we have outlined the attempts by the Mountain West socioeconomic teams, funded by $15 million in Nevada Nuclear Waste Project Office grants, to impose an "availability heuristic" and "negative images" theory on Nevada. These theories suggest humans cannot change their perceptions of unknown fears through education and that negative images and fears dictate their every action. It seems appropriate to attempt to present a non-psychological, objective analysis of the risks of Yucca Mountain in the hope that citizens can decide for themselves whether to judge Yucca Mountain on the basis of emotional fears or cold hard statistics.

YUCCA MOUNTAIN RISKS

Saying the risks from Yucca Mountain are low is not the same as saying they are non-existent; technology and life in general are inherently risky. The risks associated with Yucca Mountain are of the following sort:

TRANSPORTATION ACCIDENTS - The breach of a transportation cask within a city boundary would obviously cause damage requiring expensive remediation. Fortunately, even in an accident in which a transportation cask is hit by an airplane or engulfed in flames as in the Caldicott tunnel fire, the integrity of the robust casks is unlikely to be much affected. Even if such a breach occurred under these extreme conditions, cleanup is relatively straightforward because the radiation can be detected with simple apparatus (Geiger counters).

CRITICALITY - If water invaded the repository site through some rise in groundwater, there are certain design situations now being evaluated in which containers could reach a critical state (given complete submersion of some fraction of the repository plus the leaching of moderators from the container package).. This is not the same as a "China Syndrome" meltdown, but a situation in which a nuclear reaction would generate heat in the repository. These possibilities are under investigation.

EARTHQUAKES, VOLCANOS - As discussed before, geologic movement is perhaps the least likely to cause actual risks to the public through any affect on Yucca Mountain. Unfortunately, NWPO and the media find these to be emotional triggers.

HEAT PIPE WATER CORROSION - A hot repository can cause water vapor to accumulate and condense in fractures, allowing water to concentrate and corrode waste casks. Radioactive releases would likely be spread over substantial time. This problem is still being addressed.

GROUNDWATER CONTAMINATION - Pathways for contamination of the groundwater outside the Yucca Mountain area are effectively non-existent. The Las Vegas valley groundwater system and that of Yucca Mountain do not interconnect. Contamination of Yucca Flats would be over a timescale of millenia and then at low levels.

CARBON 14 AND IODINE 138 - Releases of both these substances for the entire Yucca Mountain site would be near those of a single reactor. Release of these gases would likely be the primary radiation exposure mechanism for humans.

These are not the only risk mechanisms, but represent the majority of risk. Present analysis suggests that there are hundreds of risks that Nevadans face each day that are orders of magnitude greater than any danger the Yucca Mountain repository poses. The limiting factor in nuclear waste risk has much to do with the inert chemistry of the spent fuel oxides.

Nuclear spent-fuel waste is composed of uranium dioxide and oxides of other transuranic metals. In other words it is a ceramic, similar to a ceramic pot or an ashtray. This material is relatively inactive: chemically, it won't explode, it melts only at extremely high temperature and if it is spilled, it is difficult to spread beyond the accident site. That isn't to say nuclear waste isn't dangerous, but most kitchens have chlorox and ammonia and other killer substances under the sink which pose significantly greater health risks, though no one panics about these deadly chemicals.

Preliminary estimates are that a person lives within five kilometers of the Yucca Mountain will receive less than one additional millirem per year of total background radiation, about one tenth the radiation of an x-ray. This compares favorably to the U.S. annual average dose of 360 mrem

SIMILARITIES TO NEVADA TEST SITE EXPERIENCE

NWPO generally argues that estimates of risks prepared by DOE are inaccurate. They have also argued that even one death per ten years, DOE's conservative estimate for total possible worldwide deaths from Yucca Mountain, is too high. Yet,. Nevadans already have been exposed for thirty years to a series of nuclear incidents as deadly as the worst case scenario for a transportation accident at Yucca Mountain, all with negligible effect. In the 1950s and early 1960s the government conducted above-ground nuclear explosions at the Test Site that Las Vegans watched from Glitter Gulch and their backyards. Compared to the threat posed by Yucca Mountain, those previous planned accidents spewed tons of radioactive material into the air.

The risk levels Nevadans will suffer from Yucca Mountain are at worst of similar magnitude as those already experienced from Test Site atomic explosions. To address the possibility that DOE has underestimated potential repository related deaths, one can gain some insight by looking at data on so-called downwinders, those who were downwind of the above-ground nuclear tests of the 1950s. Recent studies by University of Utah epidemiologist Richard Kerber and others studied these effects in thyroid tumors and cancers:

STUDY LINKS CANCERS, FALLOUT

RESEARCHERS SAY UTAH'S HIGHER THAN NORMAL RATE OF THYROID CANCER MAY BE TIED TO 1950S NUCLEAR TESTS

Schoolchildren living in Utah and Nevada during above-ground nuclear tests in the 1950s had a higher than normal incidence of thyroid cancer 30 years later, according to researchers at the University of Utah.

The study of 2,473 people likely to have been exposed to radioactive fallout from the Nevada Test Site shows "an association between thyroid tumors and exposure to radioiodine, researchers said.

The study funded by the National Cancer Institute, was published in this weeks Journal of the American Medical Association.

It was the second part of a study that looked at both thyroid diseases and leukemia. The researchers reported in 1990 the results of their leukemia work: that radioactive fallout may have been responsible for about 3 percent to 6 percent of Utajh's leukemia deaths from 1952 to 1981.

The thyroid findings are similar, said University of Utah epidemiologist Richard Kerber, one of the study's authors.

[Green, Jan; Las Vegas Review Journal November 4, 1993 pp 1A]

Since the levels of radiation exposure due to weapons tests are much larger for the test group than the population could expect from Yucca Mountain accident scenarios, applying these risk levels to Yucca Mountain would be conservative. But what do these studies really say?

For humans under the age of 65, risk of death from leukemia is approximately 1 in 10,000 per year. Consequently, even for an increased risk of 6%, this would suggest that for the exposed population of Utah and Nevada (perhaps 200,000) there would be an extra .6 cancer deaths per year.

Consequently, we can presume the risk factors presented by DOE in regard to Yucca Mountain (1/10th death per year from Yucca Mountain) are no more than an order of magnitude incorrect given the findings of the Utah study. Even a factor of ten, however, is unable to much move Yucca Mountain from the bottom of the relative risk heap in regard to other technologies and other accidfent mechanisms. For example, the recent construction of the Luxor hotel in Las Vegas, a $500 million project, saw two outright construction deaths, for a risk level of 2 deaths per year, twenty times that predicted for Yucca Mountain.

If we make a rough worse case extrapolation of possible deaths from the Yucca Mountain repository, we might estimate that as many as one death per year could be caused long term from excess radiation. For a population of nearly two million in the Yucca Mountain extended area, this corresponds to a risk of 1 in 2 million. In comparison, the risk of death from a falling airplane is 1 in 10 million, from lightening 1 in 10 million, from tornados 1 in 455,000, from earthquakes 1 in 588,000 (California), and from being struck by an automobile 1 in 20,000.

OBJECTIVE RISK ANALYSIS

Many risk assessments have been made of nuclear energy, nuclear waste disposal and transportation. Some of the most important general reviews are contained in the National Academy of Science's BEIR Committee reports (Biological Effects of Ionizing Radiation).

There are many ways of expressing quantified risk, but the one which probably puts the risks associated with Yucca Mountain in best perspective is the loss of life expectancy (LLE); i.e., the average amount by which life is shortened by a given risk. This contrasts with other measures of risk which may estimate, for example, the probability of obtaining a cancer from a radiation exposure, but do not give a feel for how this might affect one's quality of life. Certainly, a hazard that produces an immediate death at a given rate affects our quality of life more negatively than a death that occurs only after eighty years of life, albeit at the same probability.

The physicist Bernard Cohen presents an in depth discussion of lowered life expectancies from various sources in his book, The Nuclear Energy Option [Chapter 8, Plenum, 1992]. According to Cohen's analysis (see Table 8), based on numerous supporting references including the environmental community, a full nuclear program in the United States would be expected to increase average exposures by .2 millirem per year, leading to a reduced life expectancy of 37 minutes. Since local radiation exposure due to Yucca Mountain, even for those living exceptionally near the facility, is expected to be less than one millirem per year, the LLE for Yucca Mountain would be approximately 185 minutes or three hours. In comparison, the LLE of naturally occuring radon gas in homes is 35 days and the LLE from motor vehicle accidents is 180 days.

Unfortunately, the opposite question does not seem to have been analysed thoroughly - i.e., what is the lowered life expectancy due to implementing on-site storage as an alternative to Yucca Mountain. Without a definitive study, we can only make educated guesses, but there are some reasons to believe the order of magnitude of risks would be just as great as for implementing Yucca Mountain, even for Nevadans. The first reason this is so is because emissions of gaseous iodine-129 and carbon-14 will be no better isolated in on-site storage casks than in geologic storage. Moreover, since on-site storage is likely to be in the same Multi Purpose Units as proposed for Yucca Mountain, similar levels of release of other solid radioactive materials is likely to result from either scenario in the short term (long term, isolation under 800 feet of rock would make the repository safer).

Interestingly, the lowered life expectancy to Nevadans might be the same or even worse with on-site storage as with storage at Yucca Mountain. First, Nevadans are a notoriously transient population, so residents are likely to have moved from sites near on-site storage facilities and carry much of that risk with them. Secondly, on-site storage could lead to cancellation of the nuclear energy option in the U.S. making us less economically competitive. Since Cohen points out that living in poverty has an LLE of 3500 days, even a marginal negative economic impact from not building Yucca Mountain could have an LLE effect that swamps the radiation risks associated with living near a repository.ÿ