The Future of Nuclear Power Policy

[Note to reader: topic sentences are in red; remaining weakness in red.]

[Original and dramatically revised sentence outlines are available]

ABSTRACT

Sound decisions on nuclear policy require an understanding of the physical principles governing their operation, and realistic evaluations of the risks they pose. Contrary to popular belief, nuclear power reactors cannot harbor a nuclear explosion. Since both reasonable and unreasonable fears exist about the safety of reactors and of the potential dangers caused by accidents, it is useful to consider the two most serious nuclear power accidents to date, Three Mile Island and Chernobyl. Modern plant designs make such accidents unlikely to occur again. The Chernobyl plant actually had ties to nuclear weapon production, which is a fundamental concern with nuclear power, as is the disposal of nuclear wastes. Both of these issues will be discussed in the context of fuel recycling. From this it will be clear that nuclear power plants are safe enough for commercial use should stay in operation as means of reducing bomb grade materials.

Introduction

It is an unfortunate reality that many people immediately associate the word "nuclear" with images of mushroom clouds and irradiated survivors of Hiroshima. While nuclear weapons are dramatic and destructive illustrations of the energy harnessed in the nucleus of an atom, they have nothing to do with commercial nuclear power. Even in the most cataclysmic disaster, nuclear power plants will not create a nuclear explosion because they do not have the necessary types of fuel. Such misinformation and fear of the unknown have hindered the advancement of nuclear power in the United Sates, which will leave us at a technological disadvantage as fossil fuel supplies are exhausted over the next 50 years. By utilizing developed, but unimplemented technology, and by educating the general public about the realities of nuclear power, the United States can lead the way to cleaner power while, at the same time, constructively using much of what is now deemed nuclear waste.

Background

Nuclear explosions require unnaturally high concentrations of specific types, or isotopes, of uranium or plutonium. Over ninety percent of a fission bomb is a specific variety of uranium, U-235, because this isotope of uranium is conducive to the chain reaction necessary for an explosion.[1] For this reason, the explosion potential of a mass of uranium decreases as the concentration of U-235 decreases -- a significant fact because fission-able uranium comprises only 0.7% of naturally occurring uranium. [2] to bring natural uranium up to the 90% concentration of U-235 necessary for detonation requires expensive enrichment procedures which are not required for nuclear power production. Thus the fuel in a nuclear reactor does not contain enough fissionable uranium to explode.

In the worst case disaster for a nuclear reactor, known as a meltdown, the core overheats and sinks into the ground in a meltdown. A nuclear plant operates by using the nuclear fuel to produce heat. Some of the heat from t he reaction is taken away by cooling water and released as steam into the atmosphere. In the event that the cooling system malfunctions, there is the possibility that the core would overheat. If the situation becomes too severe, it is possible that the core would melt through its housing in the reactor building and burn its way into the ground.

The potential dangers of a meltdown, while unpleasant, are not as severe as those of a nuclear explosion. If the heat from the meltdown causes surrounding structure to ignite, there is a possibility that some radioactive material would be carried into the air and that some might also get into the ground water. [3] These results should not be ignored as they could result in many deaths, but the toll would be much less than in a nuclear explosion.

A realistic and productive review of nuclear power must, however, balance the potential dangers against the likelihood of occurrence. Although contested by opponents of nuclear power, the official safety report of the Nuclear Regulatory Commission, WASH-1400 (also known as the Rasmussen Report), concluded that, if there were 200 nuclear reactors operating in the United States, there would be a serious release of radiation only once in 10,000 years.[4] The report's definition of "serious release of radiation" includes more than just the worst case meltdown scenario described here.

In contrast to these unlikely dangers, nuclear release fewer pollutants and so have less impact on general health and the environment. Studies, summarized in Table 1, show that the operation of a nuclear plant is responsible for 300 time fewer days lost to illness than a coal plant producing equal power. [5] Since nuclear plants release no pollutants, they have very little potential to cause illness. In particular, they do not release the greenhouse gas, carbon dioxide. This is a serious benefit in light of the evidence for global warming and is often overlooked by environmentalists opposing nuclear power. The most surprising aspect of pollutant emission is that coal burning plants release more radioactive material into the air than nuclear plants because coal used in such plants contains traces of radioactive U-238 and Th-232 which are released int he smoke. In daily operation, nuclear plants are less of a health threat than standard coal plants.

      	        Source	       		Man-Days Lost
	       	Coal				3000
		Oil				2000
		Wind				1000
		Solar Thermal Electric		 700
		Solar Photovotaic		 700
		Methanol			 300
		Hydroelectric			  45
		Ocean Thermal			  30
		Nuclear				  10
		Natural Gas			   6
Table 1: Total Man-Days Lost per Megawatt-Year For Both Occupational Workers and the General Public.[6]

Three Mile Island and Chernobyl

Now I wish to consider in some detail the 1979 radiation release at Three Mile Island. [Not really a topic sentence.] The release was part of a partial meltdown in reactor number 2 caused by malfunctions in the equipment in the plant and poor decisions made by the operators. A minor fluctuation in the mechanical part of the system caused automated systems to make a series of changes to coolant levels at the core. The operators misinterpreted the situation, based partially on a stuck gauge, and allowed the core to become exposed. While engineers continued to misassess the situation over a two hour period, the core was damaged and radiation was released into the atmosphere,[7] but at no point was the steel safety structure surrounding the core, called the containment vessel in Figure 1, breached.[8]



[click on `Figure' for postscript
figure of reactor vessel.]
Figure 1: A typical schematic of a nuclear reactor. The steel liner is a safety device designed prevent radiation from passing out of the core area. This was not breached in the Three Mile Island accident. This feature was not installed at Chernobyl to make room for weapons manufacturing materials.
Despite the impression that the people of Middletown, PA were irrevocably damaged by the radiation released at Three Mile Island, the exposure was small compared to the exposure from natural radiation. A generous estimate of the radiation exposure due to the accident was 100 rems over the area within a 20 mile radius of the plant.[9] For comparison, the average American is exposed to 200 mrems per year from naturally occurring radon gas, and nearly 500 mrems over all sources.[10] It is likely that the natural levels of radiation near Three Mile Island are even higher than average since there is an unusually high level of radon gas in the area because of naturally occurring uranium deposits. [11] In this context, the amount of radiation emitted over such a large area is small compared to what is experienced naturally.

The 1986 explosion and fire at Chernobyl in the then-Soviet Union was much worse than the Three Mile Island accident, but could not occur in a United States reactor. The Chernobyl reactor that melted down did not have the containment features shown in Figure 1 and required and present in all reactors in the United States. These were intentionally omitted in the Soviet design because the reactor's primary purpose was the production of bomb grade materials, with power production as a pleasant side effect.[12] On the night of the accident, the administrators of the plant were running an experiment to test the performance of the reactor at levels at which they knew the core to be unstable, and to facilitate this experiment, intentionally disabled every safety system.[13] The operators were not able to maintain control once the experiment started, and, with the safety systems disabled, were unable to prevent the core from overheating.

While the core did not explode, as it cannot, the heat produced was sufficient to ignite surrounding materials. This eventually exposed the radioactive materials in the core, some of which were carried away by the smoke from the fire. The exposure of the core and the spreading due to the fires resulted in a massive release of radiation. Unlike Three Mile Island, the doses received by those near the plant were significant and did cause physical illnesses and some deaths.[14] Estimated effects of the accident for the rest of the former Soviet Union and Europe vary, but there were certainly consequences.

It is important to recognize, however, the gross incompetence required for this disaster to occur. The eventual meltdown required all of the following failures: 1) The reactor was designed without a containment system; 2) All of the safety systems were turned off; 3) The reactor design made it unstable at some power levels; and 4) The operators intentionally ran the reactor at a level where they knew it to be unstable Eliminate any one of these errors and the disaster at Chernobyl would not have happened.

Even more importantly, reactors in the United States do not have the design flaws inherent in the Chernobyl design. Modern reactors do not have an unstable operation level, and are designed so that the reaction that potentially causes a meltdown stops itself when temperatures are too high.[15] Following the disaster at Chernobyl, no one would intentionally disable the safety systems of a reactor, so that if the reaction would start to accelerate too rapidly, the system could respond to avert mishaps. So, while Chernobyl is a warning for blind foolishness, and represents the worst a nuclear accident could be, it could not happen at a United States reactor.

Admittedly, both accidents were caused by operator negligence, and operators are constantly necessary. Licensing and safety reviews of persons working in commercial nuclear facilities should be regulated the the Federal government so that regulations are uniform and so that the public may be assured that nuclear power plants will be operated safely. Plants, including Three Mile Island and Chernobyl, had sensible regulations to prevent such disasters; the problem was that the procedures were broken. The government should enforce these regulations so that competitive tendencies will not lead to safety sacrifices.

Fuel Recycling

As mentioned before, only about 0.7% of naturally occurring uranium is fissionable, but while in the reactor, the fission process produces more elements that could be used for nuclear fuel. These new fuels consist of a variety of isotopes of uranium, plutonium, and some other radioactive elements. In principle, these elements could be used to power future nuclear reactions if the spent fuel rods were reprocessed to remove them from the other true waste products. The Carter administration put a halt on all re-processing of spent fuel in the United States over fears of use in nuclear weapons, and the Clinton administration canceled the last remaining research into the viability of such re-processing. [16] Despite these choices, it is clear that re-processing of spent fuel significantly reduces the nuclear waste problem, and does not contribute to, and may even work against, nuclear proliferation.

Much of the dangerous, long-lived nuclear waste that the country is now scrambling to store are not actually wastes, but fuels that we are choosing not to utilize. The spent fuel rods generally have two types of elements: 1) True wastes which, while radioactive, are usually short lived, and 2) Potential fuels that could be burned and reduced to short lived waste. The true wastes present little storage problem as they need only be contained for days or weeks to decay into stable products, and thus would not require the massive storage facilities currently being designed. If the potential fuels were used to produce power, they would decay into the short-lived elements, and thus not require storage. Such recycling of spent fuels conserves resources and eliminates the need for long term containment.

The United States does not recycle fuel because of misconceived concerns about contributing to nuclear proliferation. One of the products of the nuclear reaction is plutonium. A particular isotope of plutonium, Pu-239, is ideal for construction of a nuclear weapon [17], but other plutonium isotopes present in the fuel are not. Although reprocessing might require plutonium to be separated from the waste, this plutonium would not be useful in for construction of a bomb. The separation can be done chemically, so that all isotopes of plutonium would be removed together. This mixture of isotopes is not useful in bomb construction. [18]

There are also concerns about transporting nuclear fuel rods for reprocessing. [Not really a topic sentence.] This argument, however, does not make sense, as fuel rods can be reprocessed on the site of the nuclear facility whereas wastes must eventually be removed. In this sense, recycling reduces the amount of radioactive material being transported.

While not contributing to nuclear proliferation, reactors designed to burn reprocessed fuel could be used to burn the surplus of weapons grade plutonium. The end of the Cold War has left nations wishing to reduce nuclear arms supplies with disposal problems. Encouraging reactors to use reprocessed fuel primes them for accepting the weapons grade materials as fuel as well. This has the potential to use constructively the stockpiles of nuclear weapons, rather than storing them at the risk of terrorist seizure.

Conclusions

While nuclear power production does require careful safety measures, it is a viable technology. Barring improbable meltdown accidents, nuclear power is safer than coal based power both in terms of general pollution and radioactive emissions. At this point, nuclear reactor design is safe enough for general use in commercial power production.

Although there have been two notable accidents, the Three Mile Island incident was not as damaging as is generally believed, and the Chernobyl accident was caused by deliberate incompetence. These events should serve as warnings that carelessness cannot be tolerated but are examples of worse case scenarios that are based on features no longer prominent in nuclear reactors. Thus they should not be construed as arguments in themselves against nuclear power.

Finally, the United States should reprocess spent fuel both to conserve resources and to lighten the nuclear waste burden. Fuel recycling will not lead to nuclear proliferation as the separation process does not separate bomb grade material from other fuels. It can, in fact, be used to reduce the stockpile of existing nuclear weapons by burning the warheads as fuel. The political concerns that stopped recycling have no scientific basis.

-----------------------------------------

[1]  Kraushaar, Jack J., and Robert A. Ristinen, Energy and Problems
     of a Technical Society, Second Edition, 1993 (John Wiley &
     Sons, Inc., New York), p 432.  
[2]  Till, Charles, Associate Lab Director of Argonne National Laboratory, 
     interviewed on Frontline.  Available at 
     <http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html>
[3]  Kraushaar and Ristinen, 1993, p. 127.
[4]  Kraushaar and Ristinen, 1993, p. 127.
[5]  Inhaber, Herbert, "Risk Evaluation," Science,  203
      (1979), P. 718.
[6]  Inhaber, 1979, p 718.
[7]  Rambo, Sylvia Hl, Chief Judge of the Middle District Court of
     Pennsylvania, in judgment of the class action suit against Metropolitan
     Edison Company (1996),
     <http:www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/tmi.html>.
[8]  Kraushaar and Ristinen, 1993, p. 128.
[9]  Rambo, 1996.
[10] Fentiman, Audeen W., Brian K. Hajek, and Joyce E. Meredith, "What
     are the Sources of Ionizing Radiation?" Radiation Education
     Resources for Ohio, RER-22 (1993 The Ohio State University), p. 1.
[11] "Nuclear Reaction," Frontline, <http://www.
     pbs.org/wgbh/pages/frontline/shows/reaction/interviews/braasch.html>.
[12] Kraushaar and Ristinen, 1993, p.129.
[13] "Nuclear Radiation"
      <http://www.pbs.org.wgbh/pages/frontline/shows/reaction/reading/Chernobyl.html>.
[14] Kraushaar and Ristinen, 1993, p. 130.
[15] Till.
[16] Till.
[17] Kraushaar and Ristinen, 1993, p. 433.
[18] Till.   

Your comments and suggestions are appreciated.
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Edited by: wilkins@mps.ohio-state.edu [May 1997]