WHAT IS RADIATION?

The story of radiation is the story of the atom and of subatomic particles. I should warn you that I love this story because it is one of the most fascinating and com­pelling stories in the history of science, it involves a cast of brilliant scientists, and it changed the world. So I get enthused and want to go into too much detail—at least that is what my students think. But to really understand the story, it will be necessary to learn some complicated and apparently nonsensical ideas in phys­ics. I will try to keep the technical details to a minimum, but if you really want to understand what radiation is and where it comes from, stick with me as we explore the story. I hope you will be fascinated, too.

The beginnings of the story go back to Indian and Greek philosophers who postulated that the universe consisted of space and indivisible particles that could combine to form more complex matter. The term atomos, meaning uncuttable or indivisible, was coined by the Greek philosopher Democritus in the fourth cen­tury B. C.E. While this was purely a philosophical speculation, it was a remarkable insight. More than a thousand years later, science and experimentation began to uncover just what this meant. John Dalton is credited with being the father of modern atomic theory in chemistry. In 1803 he developed the idea that elements consist of atoms, that different atoms have different weights, and that the atoms of a specific element are all alike but are different from those of other elements. He also proposed that atoms can combine in specific proportions to make up com­pounds or molecules (1).

But are atoms really indivisible, and if not, what are they made of? Nearly a hundred years after Dalton, this question began to be answered in a burst of experiments and insights at the end of the nineteenth century and the begin­ning of the twentieth century, starting with the discovery of radiation. In 1895 the German physicist Wilhelm Conrad Rontgen was studying emissions of light coming from evacuated glass tubes that contained a small quantity of gas and had a voltage applied to them between a cathode (negative) and anode (posi­tive). When he covered the tube with a black cardboard hood and applied a high

voltage across the tube he found that there were unknown rays coming from the tube that caused fluorescence in a nearby cardboard screen coated with a special material. This was astonishing because the black cardboard should have stopped any light. He concluded that there were some mysterious rays, which he named X-rays, coming from the tube, causing the fluorescence. He proceeded to insert various materials such as paper and aluminum between the tube and the screen and discovered that different materials absorbed these X-rays to differing degrees (2). He took a picture of his wife’s hand that clearly showed the bones in her fingers and a ring she was wearing. In a public lecture in January 1896, he took a picture of the hand of a colleague and thus began the field of radiology (Figure 6.1). Rontgen received the first Nobel Prize in Physics for his discovery of X-rays.1

This was just the beginning of an incredibly fertile revolution in physics, and it is all the more remarkable because, just prior to this time, physicists thought they knew nearly everything there was to know about physics. They understood—or thought they understood—mechanics, gravity, electricity and magnetism, optics, thermodynamics, and the statistical nature of gases. Lord Kelvin, the famous Irish-born Scottish mathematician and physicist, is reputed to have said in 1900, “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement” (3). How wrong he and other physicists were!

The French physicist Henri Becquerel discovered natural radioactiv­ity within months after Rontgen discovered X-rays. He was actually studying

phosphorescence of certain minerals because he knew that some minerals glow when they are exposed to sunlight, and he was interested in the radiation reported by Rontgen. He had already determined that if you exposed crystals of uranium salt (potassium uranyl sulfate) to sunlight for several hours while they were lying on a photographic plate that was wrapped in sheets of heavy black paper, the pho­tographic plate became exposed. He assumed that this was because of the phos­phorescence of the uranium salt caused by exposure to the sun. He was going to do further experimentation, but because of cloudy weather he wrapped the uranium salts in paper and put them in a drawer on top of wrapped photographic plates. A few days later he took the plates out and, in one of those serendipitous moments that often result in great discoveries, decided to develop the plates. Lo and behold, he found that they had been exposed, even though the uranium crys­tals had never been exposed to the sun. He concluded that the uranium was emit­ting a type of natural radiation that could pass through the paper and expose the plates. He also showed that the radiation was different from the X-rays discovered by Rontgen, but he didn’t know what it was (4, 5).

These dramatic new discoveries by Rontgen and Becquerel were followed by the discovery of two new radioactive elements—polonium and radium—by Marie and Pierre Curie in 1898. They obtained tons of pitchblende from the mines at St. Joachimstal in the Cruel Mountains bordering Germany and the Czech Republic (see Chapter 2) and very laboriously extracted a minute amount of radioactive material that was even more active than uranium. They named the first ele­ment polonium after Marie’s native country, Poland, and the second they named radium. The story of their work is one of the most compelling in the history of science. They worked in a drafty shed—with water dripping through the roof and virtually no heat in the winter—to chemically separate a fraction of a gram of radioactive material from a ton of pitchblende (6-8). The Curies and Becquerel were jointly awarded the Nobel Prize in Physics in 1903 for their discoveries of natural radioactivity.

Sandwiched between the discoveries of Becquerel and the Curies was another critical discovery by the English physicist J. J. Thomson in 1897. He was studying what were known as cathode rays in evacuated tubes, the same kind of tubes used by Rontgen to produce X-rays. He was able to show that the rays were deflected by electric and magnetic fields and ultimately determined that they were composed of particles that had a negative charge and were much lighter than atoms.2 He also showed that the X-rays discovered by Rontgen could create these particles in air (4). He initially named the small particles “negative corpuscles,” but fortunately ended up calling them “electrons.”

Now the stage was set to upend the whole understanding of classical physics because there was no theory that could explain these discoveries of X-rays and natural radioactivity. Where, exactly, did the radiation come from? Pursuing the answer to this question led to the development of a revolutionary new branch of physics known as quantum mechanics, which explained the structure of the atom and the nucleus and led to the development of the atomic bomb and nuclear power reactors.

The cooling pools at nuclear reactors are used for varying periods of time to store the spent nuclear fuel.5 For the Wolf Creek Nuclear Plant that I visited, the cool­ing pool will hold the fuel for 40 years of reactor life, but what happens after that? Other reactors are older and already have faced the problem of what to do with the used fuel rods in the short term. The short-term solution to storage of used fuel is to place them in an inert gas in steel containers encased in concrete and stored on-site at the reactor (Figure 9.3). This is called dry cask storage, which is currently being used at many nuclear reactors, and this is what will happen at

Wolf Creek Nuclear Plant after the cooling pool is filled. According to the Nuclear Regulatory Commission (NRC), about 80% of the cooling pools at nuclear reac­tors are at capacity, so dry cask storage is necessary. This only happens after the used fuel rods have been stored in cooling pools for at least five years to allow them to cool off and for some of the most radioactive elements to decay away. The heat has dissipated enough that normal airflow around the casks is sufficient to cool them. The steel containers and concrete casks shield the radiation, so it is not dangerous to be close to the casks (6).

An average-sized 1,000 megawatt nuclear reactor produces about 20 tons of spent nuclear fuel each year that has to be stored in cooling pools for a few years. Each cask typically holds about 10 tons, so the total waste from a reactor is about 2 casks per year (7). Since uranium and transuranics are heavier than lead,6 this is not a large volume. In fact, it has been calculated that the yearly waste from a typical nuclear power plant would fit in the back of a pickup (though of course it would crush it!) (8). Recall from Chapter 3 that the 280 MWe Rawhide coal-fired power plant produces 70,000 tons of fly ash annually. Thus, a 1,000 MWe coal-fired power plant would produce about 250,000 tons of fly ash or sludge waste annually. And, of course, this does not include the approximately 8 million tons of carbon dioxide (CO2) produced annually by a 1,000 MWe coal plant.

Another striking statistic is that all of the waste generated by all 104 nuclear power plants in the United States through 2010 would fill a football field to a depth of about 7 yards if all of the used fuel assemblies were laid out end to end and side to side (9). Of course, estimates like these are not realistic, because that is not how spent nuclear fuel can be stored. To be more realistic, the total amount of spent nuclear fuel generated in the United States annually is about 2,000 tons, which would require about 5 acres for dry cask storage (10).

Dry cask storage was never meant to be a long-term solution, but it has great merit as an intermediate solution over the next 50-100 years. The casks are stored on-site at nuclear reactors within the secure part of the reactor site. There is little concern about terrorist attacks because the casks are very sturdy and the spent nuclear fuel within them is useless for making bombs because of all of the fission products. While nuclear reactors normally have dry cask storage on site, there could also be several centralized depots in various states where spent nuclear fuel from numerous reactors could be stored. According to the NRC, which has to license the dry cask storage facilities, 33 states currently have dry cask storage sites. Dry cask storage—either on-site or in centralized depots—can provide a safe and secure method to handle spent nuclear fuel for the next century and can reduce the need for an immediate solution to the long-term problem of waste storage (7, 11). Furthermore, the longer the spent nuclear fuel is stored in dry casks, the more the radioactivity and heat decays, so the ultimate disposal becomes simpler and less expensive.

But is this just kicking the can down the road? What is to be done about the long-term storage of spent nuclear fuel for thousands or hundreds of thousands of years? Is this really the Achilles’ heel of nuclear power, as so many anti-nuclear activists claim it is? It is clear to me that the problem of long-term waste storage is primarily a political problem, not a scientific or engineering problem. Politics is the reason that the United States does not currently have a solution to long-term storage.

EARTH’S ENERGY BALANCE

Many factors, including carbon dioxide, aerosols, reflections from ice and snow (albedo), and clouds, affect the energy balance between incoming solar radia­tion and outgoing radiation from the earth-atmosphere system. A total of 342 watts per square meter (W/m2) of energy hit the earth’s atmosphere, which gets reflected (107 W/m2) or absorbed and re-radiated (235 W/m2 (Figure A.1).

The wavelength of re-radiated energy is longer than that of the incoming radia­tion, which allows it to be absorbed by gases such as carbon dioxide, methane, nitrous oxide, and water vapor. These gases are called “greenhouse gases” because they contribute to warming up the earth. If no greenhouse gases existed, the earth would be about 0°F (-18°C); because of greenhouse gases, the average tempera­ture is 59°F (15°C) (1). The problem occurs when the concentration of green­house gases gets too high and more of the surface radiation is trapped, heating up the earth (global warming).

The most abundant and important greenhouse gas is natural water vapor. Human activity has little direct effect on it, but the amount of water vapor increases when the earth warms. This provides a positive feedback that makes global warming worse when other greenhouse gases increase and cause the atmo­sphere to warm up. The anthropogenic greenhouse gases are those produced by human activity. These are the ones that we have control over and that are causing the concern for global warming.

The different greenhouse gases have different efficiencies for absorbing infra­red radiation, and they also have different lifetimes in the atmosphere. The actual value for CO2 is 1.4 x 10-5 W/m2/ppb. In relative terms, methane is 26 times as efficient and nitrous oxide is 216 times as efficient as CO2 in absorbing infrared radiation. However, the different gases have different lifetimes in the atmosphere. Carbon dioxide has a complex lifetime because it constantly cycles between the atmosphere and the oceans and biosphere. About 50% of a pulse of CO2 emitted into the atmosphere now will be gone in 30 years, another 15% will be gone in 100 years, but about 20% will still be present for thousands of years. Methane has a lifetime of only 12 years as it is rapidly converted to CO2 and water.

The Intergovernmental Panel on Climate Change (IPCC) uses a comparative concept called the global warming potential (GWP) to compare various green­house gases to CO2 for their potential to cause global warming. The GWP varies depending on the time frame. For example, methane has a GWP of 72 over a 20-year time frame and 25 over a 100-year time frame. This means that methane is 25 times as effective as CO2 in causing global warming over a 100-year time frame. The lifetime of nitrous oxide is 114 years, with a GWP of 289 over 20 years and 298 over 100 years (2). Since the concentration of CO2 in the atmosphere is much higher than that of methane or nitrous oxide, and we are adding it at a higher rate, it is the greenhouse gas of most concern.

Mining for conventional sources of gas associated with oil is not nearly so damag­ing to the environment as coal mining since it only involves drilling deep holes. But the methods for getting gas out of coal beds or shale do have serious problems.

The gas in these formations is not in large domes but is in relatively impermeable rock or coal and cannot be readily removed. To facilitate the removal of the gas, gas companies use a process called hydraulic fracturing or fracking, to create fis­sures in the rock so the trapped gas can be released. Wells are drilled thousands of feet vertically to reach the shale formations, and then are drilled horizontally for thousands of feet further into the shale formations. Explosions from a perforating gun pierce the casing pipe along its length and fracture the rock. Millions of gal­lons of water, along with sand and toxic but trade-secret organic chemicals and/ or acids, are then injected at high pressure into each well to widen the fractures. The sand is called a “proppant” because it is used to prop open the fractures in the shale from the high-pressure fracturing process. Up to a million gallons of wastewater flush backward through the well (“flowback”) and, of course, natural gas is collected from the deep deposits (39). Of the more than 493,000 natural gas wells in the United States in 2009, about 90% of them use fracking to release the natural gas (40).

Fracking has become very controversial recently, especially because of a docu­mentary film by Josh Fox (no relation to me) called Gasland, which gives anec­dotal evidence of toxic chemicals entering water supplies and causing health problems and even exploding houses from seepage of natural gas into the water! Numerous highly toxic and carcinogenic chemicals were identified in samples of well water after gas drilling occurred nearby. Some houses in Weld County, Colorado, the county east of where I live, had water coming out of the faucets that could be lit with a lighter! According to the film, over 596 chemicals can be used in the fracking solutions. About half of the injected water and chemicals remains in the ground and may enter aquifers, while the other half is stored in reservoirs above ground that may or may not be lined.

In response to the public outcry about fracking, the Ground Water Protection Council and the Interstate Oil and Gas Compact Commission started the website FracFocus (www. fracfocus. org) to provide a venue for accurate information about fracking. Companies can voluntarily register on the site and report the chemicals they use in fracking wells, though they may not disclose chemicals that are trade secrets. The fracking fluids fall into several different categories by function and sequence, with the exact fluids and sequence dictated by the specific shale forma­tion. The Marcellus Shale formation is fracked in the following sequence: (1) an acid stage consisting of thousands of gallons of dilute hydrochloric or muriatic acid to clean the wellbore, (2) a pad stage consisting of 100,000 gallons of “slick — water” to reduce friction in the well, (3) a prop sequence stage injecting millions of gallons of water with sand or ceramic material as a proppant to keep the frac­tures open, and (4) a flushing stage to remove the excess proppant from the well. Other additives may include biocides to reduce bacterial growth, scale inhibi­tors, iron-stabilizing compounds to prevent precipitation of iron compounds, friction-reducing agents, corrosion inhibitors, and gelling agents (41).

The gas industry has begun a big play on shale oil and gas resources in the vast Niobrara formation in eastern Colorado, Wyoming, and Nebraska. Regulators in Colorado have taken the most pro-active approach in the nation in recent regulations that require gas and oil drillers to disclose the concentrations of the chemicals they use in fracking. A few other states require disclosure of the chemi­cals but not the concentrations. Colorado requires companies to report chemi­cals that are trade secrets by disclosing the chemical family (42). Colorado also approved rules that require wells to be tested both before and after fracking to determine whether groundwater is being contaminated by fracking (43). And Colorado also approved setbacks of 500 feet from wells to residences to help miti­gate the noise and smells from drilling (44).

These disclosure rules, setbacks, and groundwater testing may go a long way to alleviating concern about fracking among the public. However, they have not prevented Colorado communities such as Longmont and Fort Collins from ban­ning fracking within city limits, a move that pits the cities against the state govern­ment (45). The state of New York has also temporarily banned fracking for natural gas, and numerous communities have also banned it. Two of the bans have been upheld in court (46). And so it goes.

Evidence is beginning to accumulate that seepage of methane and chemi­cals into groundwater as a result of fracking may be a serious problem (47, 48). Residents in the rural area near Pavilion, Wyoming—which is surrounded by more than 200 gas wells—complained of their water wells becoming contami­nated with an oil-like sheen and a fetid smell from unknown sources. After years of denial by the gas company that it could come from the gas wells, the EPA finally analyzed the water and found that 11 of 39 water samples from area wells were contaminated to varying degrees with arsenic, benzene, methane, toluene, diesel fuel, metals, adamantanes (hydrocarbons found in natural gas), and bis-phenol A. They could not prove that the contaminants came from the fracking, and some evidence indicates that they may come from the abandoned holding ponds for the toxic fracking fluids (49). The gas industry steadfastly maintains that there is no evidence that fracking causes problems with water wells or aquifers, since the wells are thousands of feet below the aquifers. But the evidence against them is mounting. The gas industry is beginning to sound like the tobacco industry in the past with its denial that smoking causes health problems. The gas industry may well be correct that the fracturing itself does not reach the aquifers, but leaks in the well casing and cement may allow fracking fluids and natural gas to leak out of the well into the aquifers.

A recent scientific study of 60 drinking water wells in the Marcellus formation in northeastern Pennsylvania showed that methane concentrations were 17 times higher in wells less than a kilometer from active drilling areas than from wells in non-drilling areas, and were high enough to be explosive (50). Furthermore, the wastewater that flushes back through the pipes (produced water) contains high levels of salts as well as radioactivity from radium. The level of radioactivity can be hundreds to thousands of times higher than that allowed in drinking water. Some of this water is treated in water treatment plants, but some of it is just dumped into rivers. Monitoring of the levels in rivers downstream from the treatment plants is not currently being done, so it is not really known whether the level of radioactiv­ity is hazardous (40).

The Piceance Basin1 gas field in the Roan Plateau of northwestern Colorado has been the site of one of the nation’s biggest drilling booms over the last decade with over 5,000 wells drilled for natural gas. Over 95% of the land surrounding the Roan Plateau has been leased to energy development companies by the Bureau of Land Management. This area is a wildlife haven, especially on the Roan Plateau itself. The network of roads and holding ponds is very destructive to the envi­ronment, and if all of the leased land is actually drilled, it will likely have major impacts on the wildlife and on the hunting and fishing economy (51). Fracking is used to extract the gas, with the excess water and unknown toxic chemicals left in holding ponds.

Because of exemptions that Congress approved in the Energy Policy Act of 2005, with strong support from Vice President Dick Cheney, the former president of Halliburton (a huge oil field-services company) and President George W. Bush, a former oil company owner, gas drillers do not have to follow the provisions of the Safe Drinking Water Act (51). As a result, the EPA has no jurisdiction to require them to line pits or make public the detailed chemicals that are injected. Scenes from the film Gasland are reminiscent of the excesses that were allowed in the 1960s before the advent of the Clean Air Act and the Clean Water Act. Scientific studies have now shown that methane from the deep natural gas forma­tions have seeped into wells as a result of fracking (47, 50), but the environmental problems associated with fracking are just beginning to be explored scientifically. The EPA is studying the environmental hazards of fracking, but political pressure is mounting to narrow the scope of the study and minimize the dangers (52).

Fracking uses 2-5 million gallons of water per well, and the availability of water could be a big problem in the arid regions of Wyoming, Colorado, and Texas, where there are major deposits of shale gas. At a Natural Gas Symposium held at Colorado State University in 2012 (53), academics, regulators, and the natu­ral gas industry discussed issues concerning water quality. According to Dr. Ken Carlson, an environmental and civil engineer at Colorado State University and head of the Colorado Water-Energy Consortium, after the well is fracked, about 30% of the fracking fluids return as flowback water, which will have some of the injected chemicals in it. In addition, over the life of the well, “produced water” comes out of the well, along with the natural gas. The produced water is high in total dissolved solids, salts, hydrocarbons (including methane), and potentially even radioactive materials. In the past this water was put in storage pits and not treated properly. But this practice is changing as regulations tighten and the public has become more concerned and involved. An additional problem with the vast amount of water, chemicals, and sand used in fracking is the amount of truck traf­fic needed to haul it in—over 1,000 truck trips per well. This can cause environ­mental damage and fray the nerves of locals where drilling occurs close to cities.

Much is known about how to properly drill and case wells to prevent gas or chemicals from migrating from the fracked shale into an aquifer and how to mini­mize water usage. Many companies use “best practices” that minimize or elimi­nate these problems. The best operators test well integrity, capture “flowback” and “produced” water and recycle it, use liners in ponds, disclose fracking fluids, and do baseline water quality measurements before drilling so that any effects from fracking can be analyzed scientifically. However, there are hundreds of drilling operators in Colorado, and not all of them use best practices. It is like the “dirty car syndrome” in which only a few percent of cars cause most of the air pollu­tion. In the case of natural gas fracking, a few bad operators can cause most of the problems. Ideally, the regulatory agencies, such as the Colorado Oil and Gas Conservation Commission (COGCC), would ferret out any problems, but there are far too few inspectors to make sure the rules are being followed.

New drilling technology used with fracking allows for more than 20 wells to be drilled from a single wellhead, with the wells spreading out horizontally to drill underneath populated or sensitive areas. This can greatly reduce the number of wellhead sites in a given area and reduce the environmental impact.

Contamination of water wells and aquifers is not the only potential problem with fracking for natural gas. In March 2012, the Ohio Department of Natural Resources determined that a dozen small earthquakes were caused in areas where fracking was done. How can this happen? It is not a direct result of the fracking but from trying to responsibly deal with the millions of gallons of wastewater pro­duced per well. The EPA allows this water to be pumped into very deep storage wells so that it doesn’t contaminate aquifers or surface water. The injection wells were in the area of a previously unknown fault line that caused the earthquakes after fracking. The Ohio governor called for a moratorium on shale gas production at that site after a 4.0 magnitude earthquake occurred near Youngstown, Ohio (54).

On September 10, 2010, a gas pipeline explosion in San Francisco killed eight people and destroyed 38 homes (55, 56). This is but one of a number of gas explosions over the years that have killed or caused serious injuries to people and damaged property. More recently, another gas explosion killed five people in Allentown, Pennsylvania (57). According to the National Pipeline and Hazardous Materials Safety Administration (PHMSA), which is in charge of pipeline safety, an average of 45 serious incidents (incidents that caused death or serious injury) occurred each year for the past decade in the United States. There are 321,000 miles of gathering and transmission pipelines in the United States that bring the natural gas from the wellhead to a gas transmission system that covers the nation. Over 2 million miles of pipeline then distribute the gas to homes, businesses, and power plants. Thus, it is inevitable that accidents will happen, and their incidence will most likely increase as the use of natural gas for power production increases.

So natural gas is not really the solution to the energy problem. It is clearly better than coal (especially if fugitive emissions are controlled), and its use is expected to increase substantially as coal power plants are phased out and wind turbine power increases, but it will still be a major contributor to global warming. The issues associated with drilling and fracking are likely to become more important, and it will be up to the industry to change their procedures to minimize road-building in wilderness areas and protect water. As Josh Fox, the producer of Gasland, says with some hyperbole: “We’re in the position right now of trading a short term energy fix and money for the future of our water in America” (58). Let’s make sure that is not the Faustian bargain we make.

Because coal and natural gas have so many “bad” and “ugly” attributes, with the only “good” being that they are plentiful, it is imperative that we wean ourselves from our dependence on these forms of energy. If a choice has to be made—and it will—then the first priority is to drastically reduce the use of coal for electricity production, even if that entails a greater reliability on natural gas. That is not the end of the story, however. What about renewable energy from the sun? Will it solve our energy and global warming problem? That is the topic for the next chapter.

The final way in which photons interact is another one of those Alice in Wonderland events that may seem impossible to believe. A photon with energy greater than 1 million electron volts (MeV) (in the presence of a nucleus to con­serve momentum) gives up all of its energy to create two new particles, a nega­tive electron and a positive electron (positron), according to Einstein’s equation, E = mc2 (Figure 7.3). It takes slightly over 1 MeV of energy to create the mass of two electrons. Any excess energy in the original photon is given up as kinetic energy of the electrons. The positive electron rapidly loses energy through col­lisions and finally engages in a dance of death with a regular negative electron; then they annihilate each other, creating two у photons, each with energy of 511 keV moving in opposite directions, thus converting mass back into pure energy. Energy becomes mass becomes energy! Ah, the strange things that happen in the atomic world!

The net effect of all of these types of electromagnetic interactions is that the X-rays and у rays are absorbed by matter in an exponential manner. That is, the number of X-rays or у rays and their dose decrease exponentially as they pass through matter (Figure 7.4). The more energetic they are, the farther they will travel, but even low energy X-rays used in radiology (around 70 to 100 keV) have plenty of energy to travel several inches through your body. The photons give up their energy by ionizing atoms and giving energy to electrons. It is the electrons that contribute most of the dose from energetic photons.

It used to be that the exclusion zone was closed to ordinary people—reserved for scientists, journalists, and others with special access. But that is not the case now. Tour buses regularly come to Chernobyl to visit the radioactive area. You can also get special individual tours through web sites such as http://www. ukrainianweb. com/chernobyl_ukraine. htm#Chernobyl. All tours are managed by the Ministry of Emergency Situations of Ukraine and are highly regulated.

Yuri picked me up at my apartment in Kiev and we drove to the Dnieper River pier to pick up a Danish couple who were on a river cruise and wanted to see Chernobyl. We drove through the countryside and small villages for an hour and a half or so until we arrived at the checkpoint to the 30-kilometer exclusion zone where we met our guide, Maxim Orel. He likes to joke around but he also has a dark, cynical side. The Chernobyl accident and the lack of faith in the authori­ties to tell the truth about the accident have left their psychological mark on the Ukrainian people.

The first stop is a newly built museum that is not very informative about the actual accident and is mostly a shrine to the people killed in the accident and to children. Similar to the very misleading Chernobyl Museum in Kiev, it implies that far more children died or suffered gross abnormalities than is the actual case. Maxim told me that 120,000 people had already died within the first 10 years after the accident, presumably quoting the very misleading Greenpeace study. I set him straight on the scientific analysis of the expected number of deaths.

Outside the museum is a concrete slab representing the 30-kilometer exclusion zone with another smaller slab on top of it representing the 10-kilometer exclu­sion zone that has higher levels of radiation. There are bases in the concrete to plant signs for each of the 90 or so villages that have been evacuated. Signs with the names of the villages with a line through them form a long lane on past the concrete slab. It is sobering.

We are in the town of Chernobyl (Chornobyl in Ukrainian), about 15 kilo­meters from the nuclear plant. Maxim said it was a Jewish settlement of 30,700 residents since Jews could not live nearer than 100 kilometers from certain cities in Soviet times, and Chornobyl is about 120 kilometers from Kiev. The Stalinist forced starvations of the early 1930s and the Nazi holocaust had decimated the Jewish population. By the time of the accident, there were about 14,000 residents in Chornobyl. There are no permanent residents now, only workers who cycle in and out to keep their doses below the maximum limit—though Maxim didn’t know what the limit is. The workers are environmentalists, scientists, and admin­istrative personnel who are needed to run the place and do scientific studies. Maxim had a handheld dosimeter and I measured the background radiation at around 0.23 |aSv/hr—nothing to worry about (equivalent to 2.0 mSv if you were there for a year).

There are 113 self-settlers in the exclusion zone. These are people in their sev­enties to nineties who decided to come back and live out their lives in the old villages. The government provides them with electricity and basic essentials. They get monthly medical care and can get emergency medical care also. They will die in their old homes, happy to be there but cut off from normal society. They won’t die from the radiation but from old age.

We left Chornobyl and stopped at a site storing Japanese robots that were used after the accident to try to deal with the disaster. They only worked for a few days before the radiation disabled them. We also stopped at a memorial to the firemen who died fighting the fire spewing from the damaged reactor. These were the 28 people who died early on from acute radiation effects. They were the true heroes of Chernobyl.

As we continued our trek toward the reactor site, Maxim said we could not enter the buildings in Pripyat because the authorities changed the rules a few months ago—too dangerous for people to be in the buildings, not from radiation but general safety hazards. So we stopped at Kopatchi, a little village that no longer exists except for a kindergarten that still stands. The building is falling apart, with parts of the ceiling coming down and the floors covered with junk, and you could see children’s playthings, beds in a dormitory, old lockers, alphabet letters in a pile on the floor. It is what you might imagine if a kindergarten were abandoned very suddenly and over time it was ransacked—exactly what happened. The dose rate inside the building was about the same as background in Chornobyl but outside it was much higher. I walked around the building and it was around 5 pSv/hr. As we were leaving, Maxim showed us a spot that had been a play area with some old toys gradually decaying away where the dose rate was 40 pSv/hr—about 350 mSv if you stayed on that spot for a year.

As we approached the reactor, Maxim emphasized that the authorities rather arbitrarily keep various sights and even pictures off-limits. “It is not allowed” is a favorite expression. We stopped at a distance from the nuclear plant site and took pictures of reactors 1 and 2 that continued to run for several years but were deactivated on President Kuchma’s orders. Two reactors were in a single building with a smokestack and cooling tower. The deactivated reactor building was cov­ered with rust but presumably has been properly shut down with the fuel removed and put in a cooling pool. The French were building a storage facility for han­dling the spent nuclear fuel—the building was opposite the road from our viewing site. Pictures were not allowed. After spending 300 million euros, the project was abandoned. Maxim did not know why and said it is dangerous to ask questions about such things.

We drove on to a parking lot and observation point near reactors 3 and 4, which were also in a single building. One side looks relatively normal and contains reac­tor 3, which continued to operate until 2000. The other side is the destroyed reac­tor with a sarcophagus (shelter object) covering it. There is a memorial at the site and you can get good pictures of the reactor. The sarcophagus was clearly made haphazardly and is leaking—hardly surprising, given the extreme condi­tions at the destroyed reactor when it was built to encase the holocaust. It was not built to last forever and it certainly won’t. According to Mary Mycio, water leaks through cracks and forms pools inside with more than half as much water as an Olympic-sized swimming pool (16). Maxim said the dose rate inside is 3,000 R/ hr. I asked him about a model of the destroyed reactor showing the elephant’s foot—the melted slag heap of nuclear fuel and who knows what else pooled on the floor of what remains of the reactor—and he said you needed special permission to see that and it takes a day and a separate form. He made phone calls to try to get us in—unsuccessfully because there was a group of scientists and engineers touring the site already.

Right next to reactor 4 is the ongoing construction of the New Safe Confinement (NSC). According to a 3D-CAD model video we saw in the museum, the NSC will be a huge arch 108 meters (354 ft.) high with a span of 257 meters (843 ft.) and 162 meters (531 ft.) long. It is being built in sections on huge towers and will then be slid forward on huge concrete rails to cover the destroyed reactor. Once it is finished and in place over the sarcophagus, it will have the capability to remotely disassemble the panels and beams that constitute the sarcophagus, with the eventual goal of decontaminating the site. It is designed to last for at least 100 years, though it may last much longer. Work seems to be pretty well advanced, with the large towers built and several of the sections of the arch seemingly com­pleted. It is being built by Bechtel, EDF, Battelle, and KSK (a Ukrainian subcon­tractor). Maxim says it is now scheduled for completion in 2015, and that seems pretty realistic from what I saw. He said it is forbidden to take pictures—why that is so is not at all apparent, since it doesn’t appear to be a secret at all. Maxim says that the authorities are taking pictures of everyone, and the tour guides can get in a lot of trouble if they try to bend the rules.

Leaving the reactor site, we headed to Pripyat. On the way we came to an inter­section that was at the edge of the Red Forest, a 4.5-square-mile pine forest that was directly in line of the worst fallout from the reactor. From this single van­tage point the pine trees appear to be mostly gone and a birch forest has taken over. That would be like the natural succession of a pine forest that burned to the ground. In reality, the pine trees of the Red Forest were bulldozed down and bur­ied and pine trees were later planted, but they are stunted by the still-high levels of radiation. The birch trees are much less sensitive to radiation, so they are out­growing the pines. The whole exclusion zone is covered with trees and grasslands as it reverts to the wild. Fall had not yet arrived, so few of the leaves had their fall colors yet.

We are in Pripyat, the abandoned town that used to be a high-end town for the young nuclear workers and their families. The town was built in the 1970s solely to support workers at the reactor complex. The afternoon after the accident, the workers were told to pack their things for a few days, but of course it turned out to be forever. That was done to prevent panic, supposedly. These were the lucky people who got potassium iodide pills, which probably prevented a lot of thyroid cancers among the children. As you drive up the promenade to the main town square, the trees growing everywhere obscure the buildings along the street. The town square was a large concrete open area with a couple of fountains that now have trees pushing through the concrete and small ponds in the former fountains (Figure 10.2). Moss grows along cracks in the pavement. The moss is somewhat more radioactive than the general area—I measured doses of around 2 qSv/hr (18 mSv/yr) in the plaza. The large building on the far side of the plaza was the Cultural Palace where theater productions were held, as well as a bowling alley and other entertainment options for the residents. It is falling apart. We were able to go inside part of the theater, even though “it was forbidden," where you could see the stage lights fallen to the floor and posters of communist officials, including Lenin. It was surreal. The whole area is reminiscent of a Mayan jungle taking over the ancient ruins of the people. That is exactly what is happening here and on an amazingly rapid time scale. After all, the accident only happened 27 years ago and already Pripyat is a wild forest. Trees grow through concrete and pavement and up through buildings. It is fantastic!

We walked to the Amusement Park where the famous Ferris wheel stands as a stark monument. It was never used—the Amusement Park was supposed to open on May 1, three days after the accident. A merry-go-round is nearby—rusted

relics of the man-made disaster that was Chernobyl. Near the bumper car arena filled with the skeletons of rusted cars is a hot spot where the dose rate was 200 ^Sv/hr—an amazing 1.6 Sv/yr.

We drove down old streets through the forest to the swimming pool. It is sur­rounded by forest and flowers. All of the huge windows surrounding the building are broken, but you can go into the swimming pool area that has intermediate and high dive platforms. There is a ruined basketball arena and on the upper level were rooms with ferns growing in cracks along the walls—nature taking over. Next we drove to the high school and toured the abandoned building of long hall­ways and classrooms. The dining room floor was covered with gas masks. They kept gas masks there and had regular drills because of the fear of gas or chemical weapons being used—old Cold War fears, I guess. Apparently the liquidators used the gas masks and the school building and left them all in the dining hall. Parts of the hallway and some of the rooms were filled with ruined books scattered on the floor. Why they were all thrown on the floor is a mystery, though Maxim tried unsuccessfully to explain it. Presumably scavengers took what they wanted but didn’t want books. In what was obviously a science room, there was an old chart of electromagnetic radiation on the wall—an interesting icon for the nuclear disaster!

We were running late for lunch—it was already 2:30—so we left and headed to the cafeteria. There were several tour buses there, so we had to wait about 15 minutes to get in. It was a decent and very filling lunch—but no mushrooms or berries! our last stop after lunch was to the cooling pond canal to feed the catfish! We threw pieces of bread from our lunch into the water and watched fish mill around to eat it. Smaller fish were going crazy but in the right spot in the middle of the railroad bridge you could see the large catfish congregate. They were very selective in what they ate. Apparently they got plenty of food. Maxim said these were just babies—only about 30 to 40 kilograms. The big ones in the main cooling pond run 300 to 400 kilograms! This is not due to the radiation, of course, but to the fact that there are no top predators, since fishing is not allowed.

I had hoped to see some birds or wildlife but did not really expect to. I saw a few crows, magpies, and hawks but no white-tailed eagles or black storks; also no wild pigs or any other wildlife. We were there in mid-day and not in the outlying areas of the exclusion zone, so I was not surprised but a bit disappointed. Still, it was a very interesting trip into “Chernobyl Radioactive Park”!

What is one to make of this place? As far as humans are concerned, it is a disas­ter for the people who had to leave their homes and establish themselves in new communities. And of course, it was a disaster for those who died from the radia­tion and a problem for the children who got thyroid cancer and will have to take thyroxin supplements for the rest of their lives. But the “Children of Chernobyl” organization is hyping the problem by trying to make everyone victims when most of the problems they report have nothing to do with the radiation.

As far as nature goes, the accident was a good thing. Since people are excluded, the plants, trees, birds, and animals are taking over. In spite of high radiation levels in some parts, nature is thriving. The best thing to do is to prevent people from ever coming back here to live and let nature rule. There are poachers and others who come to the forest, but the police try to keep them out. Hopefully the government will never decide to bring people back but will leave it as a wildlife preserve and a tourist destination. When you are in Pripyat away from the tour buses, it is so quiet and peaceful you can forget that civilization exists. That is the way it should be in this sacred place.

We left the exclusion zone and went through a full-body radiation scanner to detect any radiation picked up on our clothes or shoes. We were “normal” so we left the zone and headed back to Kiev. Quite a day!

Consequences for Nuclear Power

It is hard to generalize from the Chernobyl accident since the type of reactor is not operated anywhere else in the world outside the former Soviet Union, and all of the existing RBMK reactors in the Russian Federation have now been modified so that they would not suffer the same sequence of events that led to the accident, even given the same kind of operator errors. The design of western reactors was not affected, since none of them operated like the RBMK reactors.

Nevertheless, reactor safety became a worldwide issue. With Chernobyl com­ing on the heels of Three Mile Island, the world became more leery of nuclear power, with some countries becoming extremely anti-nuclear. Italy shut down its nuclear reactors in 1990 in response to Chernobyl, and Germany finished build­ing its last of 17 nuclear reactors in 1989 (35). The Chernobyl accident added to the pressure to end the building of new nuclear reactors in the United States. But over time, the worries about nuclear power were receding and nuclear reactors were being planned and built rapidly, particularly in Asia.

This is where I was going to conclude this chapter on accidents, but while I was writing the book, a natural catastrophe caused a nuclear accident in Japan and set the nuclear fear demons loose once again.

Wind and solar have a place in the energy portfolio of the United States and the world and I support their development where it makes environmental and eco­nomic sense. They are renewable and they have low emissions of CO2 from their production and installation, and none from their operation. But they do not solve the energy problem. They can contribute the most power in areas where relatively few people live, requiring a huge and expensive new network of transmission lines to be built to get the electricity to markets. They are expensive and require large subsidies for them to be competitive. They have environmental consequences because of their very large footprints, which restrict them in many places. They are not very long lived as power sources, with effective lifetimes of around 20 years. And they do not reduce the need for fossil fuels to provide the baseload electricity that electrical grids depend on because of their intermittent nature. At best, they can provide about one-fifth of the electricity needs of the country, varying some­what by location, even with a massive investment and hundreds of thousands of wind turbines all over the country.

So if wind and solar are not able to wean us from our addiction to coal and nat­ural gas for electricity production, is there any environmentally friendly resource that can? That is the subject of the next chapter and the main topic of this book.

Perhaps the most intensely studied human population in history are the approxi­mately 90,000 survivors of the Japanese bombing who have been followed since the war in what is known as the Life Span Study. The United States National Academy of Sciences established the Atomic Bomb Casualty Commission in 1947 to study the health effects of the bomb survivors. This later morphed into the Radiation Effects Research Foundation (RERF),4 a joint US-Japan research effort to continue studies of the survivors in order to better understand the health effects of radia­tion. Of the nearly 200,000 survivors that were living in the cities of Hiroshima and Nagasaki at the time of the bombing, 120,321 were included in the Life Span Study. This number includes 93,741 who were within 10,000 meters of the hypocenter of the bomb and 26,580 people who were not in the city at the time of the bombing and constitute control populations (30). Individual dose estimates are available for 93% of the irradiated individuals. The incidence of cancer and all causes of death are followed rigorously in the people included in the Life Span Study. This database constitutes the primary basis for determining the risk of getting cancer from a cer­tain dose of radiation. Out of about 48,000 people who received doses of 5 mSv or more, 6,308 had cancer by 2003—the latest year of compilation—but only 525 of these could be attributed to radiation, judging from the spontaneous incidence of cancers from a similar size population who were not irradiated (32).

The United Nations Scientific Committee on the Effects of Radiation (UNSCEAR) and the US National Academy of Sciences Committee on the Biological Effects of Radiation (BEIR) periodically review the data from the Life Span Study, as well as fundamental research on carcinogenesis, and publish reports that form the scientific consensus on the risks of cancer from radiation. The latest BEIR VII report was published in 2006 (29). The risks are analyzed based on the specific site of a cancer, the age and sex of the individual, and the dose of radiation the individual received. The bottom line is that the risk of cancer is thought to be linearly related to dose, so that the larger the dose, the greater the risk.5 To put it into perspective, out of a group of 100 non-exposed people, 42 will normally get some type of cancer. If these same 100 people were exposed to a dose of 100 mSv (0.1 Sv), one additional person would get cancer (Figure 7.6).

That dose would be about 40 times the average natural background radiation that people are exposed to around the world.

There is an ongoing scientific discussion about whether a linear no-threshold (LNT) dose-risk model is the best model, or whether it overstates the risk. The sci­entific issues center on experimental results that show both an enhanced effect of radiation from what is known as the “bystander effect“ and a reduced effect from what is known as “hormesis" The bystander effect is the ability of cells that have been irradiated to cause effects on bystander cells that have not been irradiated, thus enhancing the action of a dose of radiation (33). Hormesis is an adaptation to a small dose of radiation or other toxic agents such that subsequent doses have less of an effect (34, 35). Both effects are supported by numerous scientific studies on cells, but it is still not clear what effects they have on radiation-induced cancer in humans. So the consensus is still to use an LNT dose risk model, and the latest results from the Life Span Study strongly support that hypothesis (32).

That is not quite the end of the story. The International Commission on Radiological Protection (ICRP) and the US National Council on Radiation Protection and Measurements (NCRP) are international and national organizations that recommend dose limits based on the scientific reports that are enforced by regulatory agencies. The scientific studies and these organizations recognize that the risks of radiation are based on the Japanese bomb survivors who were exposed to high doses given very rapidly, yet most people exposed to radiation from a nuclear accident will have relatively low exposures at a low dose rate. This reduces the actual risk of cancer by a factor of about two, which is known as the Dose and Dose Rate Effectiveness Factor (DDREF). Furthermore, the risk of cancer is lower for people exposed as adults, compared to being exposed as children. The ICRP concludes that the risk of death from cancer for doses below 200 mSv is 4% per Sv for adults and 5% per Sv for a population that includes children. These risks are doubled to 8% and 10% for doses higher than 200 mSv given at a high dose rate. So that is the bottom line. You can then predict the risk of dying from cancer from a given dose of radia­tion by simply multiplying this risk factor by the actual dose.

Since 1987, the United States and the countries of the former Soviet Union have signed disarmament treaties to reduce nuclear weapons stockpiles by about 80%. Nuclear weapons have both highly enriched uranium (HEU) of at least 90% 235U and plutonium that can be refabricated and used as nuclear fuel. HEU can be blended down with depleted uranium—the mostly 238U that is left over after enrichment for 235U—or natural uranium to make the low enriched uranium (LEU) of 3-4% that is used in nuclear reactors. There are about 2,000 tonnes of HEU in US and Russian nuclear weapons stockpiles, about 12 times the annual world mining production of uranium. Plutonium can also be blended with ura­nium to make a mixed oxide fuel (MOX) that can be burned in regular reac­tors. This is the same process that I discussed in Chapter 9 for reprocessing spent nuclear fuel to make MOX that is used in nuclear reactors in France. The stock­piles of plutonium in nuclear weapons is about 260 tonnes, equivalent to about a year’s worth of uranium production (49).

In 1993 the United States and Russia signed a historic agreement known as the Megatons to Megawatts program for Russia to convert 500 tonnes of HEU from warheads to LEU that would be bought by the United States to be used in civil­ian nuclear reactors. A contract was signed in 1994 between the US Enrichment Corporation (USEC) and the Russian counterpart, Technabexport (Tenex), to implement the agreement. As a result, the United States will have bought at least 500 tonnes of HEU converted to reactor fuel by 2013 when the program ends. USEC is also down-blending 174 tonnes of US HEU from weapons stockpiles to make into reactor fuel. This program is producing 10,600 tonnes of uranium annually, the biggest component in making up for the shortfall between mining production and use in reactors (49). As of the end of 2012, nearly 19,000 warheads had been converted into fuel for nuclear reactors, providing half of all nuclear power in the United States, which is about 10% of all electricity produced in the nation (50, 51).

The United States is in the process ofbuilding a plant at the Savannah River in South Carolina with AREVA, the French nuclear company, to convert plutonium in US nuclear weapons to MOX (see Chapter 9). Over 60 tons of plutonium from US nuclear warheads are expected to be eventually converted to MOX fuel at the Savannah River plant.

ACKNOWLEDGMENTS

The idea for this book arose from the college class on radiation biology that I taught for many years, though I was always too busy teaching and mentoring graduate students to write it. When I retired I finally had the time to do it. I want to first acknowledge my students over the years who have been at the core of my scientific life. They have inspired me and challenged me. Working with them has been the greatest pleasure of my career and has made my life fulfilling. Without them, this book would never have been written.

Scientific colleagues in my department at Colorado State University have read chapters or the entire book and made invaluable comments. Ward Whicker, an internationally renowned radioecologist, colleague, and friend, read every chap­ter as it was written and made sure my scientific facts were accurate. His positive comments strongly encouraged me to keep writing until it was done. Joel Bedford, an internationally renowned radiation biologist, colleague, and friend, was my postdoctoral advisor and has always been a scientific mentor. He taught me how to grow mammalian cells and do radiation biology experiments. He read parts of the book, particularly the chapter on radiation biology, and made sure it accu­rately portrayed the scientific understanding of how radiation damages DNA and cells. Of course, any errors I have made are my own, not theirs. John Pinder gave lectures in my undergraduate class on radiation in the environment, particularly the radioisotopes released after a nuclear accident. I learned much from him, as is reflected in the chapter on accidents. He also contributed a figure for the book. Tom Borak helped my understanding of radiation physics and also contributed a figure for the book.

Friends and family have made equally important contributions to the book. Hans West faithfully read the entire manuscript and made numerous and impor­tant comments from his diverse perspectives that have improved the book. Judy Mohler read every chapter and gave the perspective of a non-scientist who is deeply concerned about the environment. Her comments helped to ensure that the book would be accessible to a non-scientific audience. My thanks also go to Gary Fox, Steve Mohler, Terri Torres, Mitch Magdovitz, and Jennifer Magdovitz, who read and commented on one or more chapters.

I am indebted to various people who led me on tours through various nuclear installations and coal-fired power plants and/or provided technical information. These include Tom Moreau at the Wolf Creek Nuclear Generating Station, and Jon Little and Dave Ussery at the Rawhide Energy Station. Michael McMahon gave me a tour of AREVAs La Hague recycling plant in France. Joe Faldowski gave me a tour of AREVAs Melox plant, which uses the plutonium recycled at the La Hague plant to make MOX fuel. Both Michael and Joe read the chapter on nuclear waste and made numerous and excellent comments. Richard Clement of Powertech read the chapter on uranium and made sure my information about in situ uranium mining and the uranium market was accurate. Maxim Orel was my guide to see the Exclusion Zone around Chernobyl.

I am deeply indebted to Mary Ann, my wife of many years, who has always sup­ported me through the ups and downs of my career. She read many chapters of the book and alerted me when my writing was unclear or too technical. She also kept a flow of news items related to nuclear or renewable energy coming my way. More than that, she has been the guiding light of my life.

Finally, I thank my agent Stan Wakefield for finding a publisher for my book and my editor Jeremy Lewis for promoting my book at Oxford University Press.

Why We Need Nuclear Power