Sunday, January 6, 2013

Future Nuclear Energy Sources

This is my second attempt to return to blogging after a serious illness. The first attempt was thwarted by various relapses in addition to deterioration of my vision which has left me in a state of near blindness. I would like to thank my wife, Becky, for her assistance in relaunching my blog. Aside from my eyesight, my health definitely appears to be on the mend. My eyesight unfortunately cannot be corrected. I just have to live with it. 

The return to life after near death changes a person and it has changed the way I look at energy.

We face an increasingly severe climate crisis driven by carbon dioxide in the atmosphere. The primary culprit in this crisis is fossil fuel. At the same time fossil fuel companies are campaigning for continued dominance of fossil fuel in the energy market. Advocates of both fossil fuel and so called green energy are opposed to both nuclear power and the development of nuclear technology.

Fossil fuel companies oppose nuclear power because it offers routes to fossil fuel replacement by non-carbon energy sources.  Even the critics of nuclear power can see that nuclear power can produce many different types of energy without the creation of carbon dioxide in the atmosphere. Advocates of renewable energy are not necessarily opposed to nuclear power, however a number of ideologically based environmental organizations oppose nuclear power in principal citing safety problems, nuclear waste, nuclear proliferation, and capital cost of nuclear generating stations.

Some critics of nuclear power tend to think all forms of nuclear power are the same. They believe that all reactors have the same safety problems, the same nuclear waste disposal problems, the same nuclear proliferation problems, and the same capital cost problems. In fact, advanced well tested technologies have very different safety, waste disposal, and capital cost characteristics. Even among water cooled commercial reactors, recent designs have safety features that make the reactors far safer than the Three Mile Island and Chernobyl reactors as well as the Fukushima Daiichi reactors that recently experienced core melt down. Advanced reactors are even safer and in some cases approaching ultimate safety standards. They will not experience accidents that kill or injure people or damage property. Critics of nuclear power often ignore the different safety potentials of different reactor designs and fail to recognize that nuclear power is potentially the safest source of energy for future society.

Light Water Reactors act like boilers. Water is heated above its' boiling point and at the same time it is kept under high pressure to prevent boiling. Coolant water travels through the core of Light Water Reactors acting as a neutron moderator and a coolant. Water leaves the core under heavy pressure and flows through a heat exchange then returns to the core. Water from the heat exchange is carried into a secondary heat exchange at which time it heats boiling water that drives steam turbines. These steam turbines produce electricity. The safety problems of Light Water Reactors has to do with the presence of water in their core. Too much pressure in the reactor core can lead to a steam explosion which may shatter the outer vessel of the core. In that case water may escape the core and nuclear processes going on in the core can begin a melt down. Water pipes serving the reactor may leak water leading to a loss of coolant accident.

Some Liquid Metal Reactors pose some safety problems. For example, the sodium in Liquid Sodium Cooled Reactors is dangerous if it leaks into the atmosphere. sodium burns when it comes into contact with oxygen in the air and oxygen in the form of water. The sodium safety problem has confronted Sodium Cooled Reactor development programs for a long time, but the scientists and engineers in those programs now say that they have gotten a handle on the sodium flammability problem and that they can develop sodium cooled reactors that are as safe, if not safer, than commercial water cooled reactors. Nuclear fuel for Sodium Cooled Reactors is fabricated in three forms. The problem of nuclear waste can largely be solved for Sodium Cooled Reactors depending on which of those forms is used. Sodium reactor developers claim that they can build Sodium Cooled Reactors that are as safe as the latest generation of water cooled reactors. Such reactors could largely solve the problem of nuclear waste.

The problem of waste in water cooled reactors stems from the relatively large amount of fuel that must be used in order to produced nuclear energy; thus over ninety percent of the fuel that is inserted in the reactor comes out in the form of waste. The fuel process of conventional reactors is wasteful, although far less wasteful than that used in coal fired steam generators. Some technologically advanced reactors produce far less nuclear waste than conventional Light Water Reactors. Thus, the problem of nuclear waste is not a justification for the rejection of all forms of nuclear power.

Scientists have proposed a number of methods for dealing with nuclear waste. These methods would undoubtedly work and would pose little danger to the public over many thousand years of time. They would be inexpensive enough to not contribute significantly to nuclear generated electrical cost. The nuclear waste problem is political. It is created by the arguments of critics of nuclear power who wish to convince the public that the nuclear waste problem is impossible to solve.

Waste problems associated with Lead Cooled Reactors have not been well reported in the West and therefore they cannot be assessed.

Molten Salt Reactors, at worst, produce less nuclear waste than conventional reactors. At best, a Molten Salt Reactor would produce virtually no nuclear waste. Molten Salt Breeder Reactors typically use far less fuel than conventional reactors and probably far less fuel than liquid metal breeder reactors. Half of the wastes produced by Molten Salt Reactors reaches a state of stability in a relatively short amount of time; that is, its radiation dissipates within a few years. The dissipated wastes can be recycled into the industrial economy. Some of the minerals in the dissipated wastes are very valuable. Other radioactive materials have a variety of uses, for example radioactive Thallium is used in medicine. Radiation from radioactive wastes can be used for food preservation, water purification, and a variety of other industrial purposes. Long term radioactive wastes would amount to several hundred pounds of wastes produced every year. This can be stored without any danger to future residents of planet Earth. Most long term wastes produces relatively harmless amounts of radiation. Most people are in far more danger of radiation from dental X-rays and chest X-rays as well as CT scans.

Conventional Light Water Reactors would not be useful tools for nuclear proliferation. Their uranium oxide based fuel creates a great deal of difficulty for anyone who wants to extract fissionable isotopes from spent Light Water Reactor fuel. A simple low cost Graphite Reactor would serve as a far better source of fissionable materials that could be used for bomb making purposes. Graphite Reactors designed in the United States during WWII were good Plutonium production tools and could be built for far less than conventional Light Water Reactors. One such reactor was built less than twenty miles from my home in Knoxville, Tennessee, and is still open for public viewing.

The nuclear proliferation problems associated with Sodium Cooled Reactors are significant. Unlike water, which acts as a neutron moderator, sodium does not slow down the speed of fission produced neutrons. When high speed neutrons hit U-238 atoms, they start a chain of nuclear events that leads to the production of fissionable Pu-239. When Pu-239 fissions, it produces about three neutrons and thus it is possible to produce more fissionable material than is used in a Sodium Cooled Breeder Reactor. Some scientists, most notably Enrico Fermi, saw the breeding potential of Sodium Cooled Breeding Reactors as a means of providing energy to the world for thousands of years to come. This idea spread around the world from the United States to the United Kingdom, France, the Soviet Union, India, China, and Japan. To date, development of these reactors has been difficult, but scientists in India believe that they will be producing commercial Sodium Cooled Breeder Reactors before the end of the present decade.

Sodium Cooled Breeder Reactor prototypes have been, to date, more expensive than their water cooled commercial counter types. While Sodium Cooled Breeder Reactor advocates claim that the cost of Sodium Cooled Breeder Reactors can be lowered over time. The case for this argument has yet to be laid out. Critics of nuclear power suggests that Sodium Cooled Breeder Reactors would be a useful tool for rogue states to produce nuclear weapons. At the same time, the same critics charge that Sodium Cooled Breeder Reactors would be too expensive to compete with other energy sources; thus the Sodium Cooled Breeder Reactor would not appear to be an attractive tool for nuclear proliferation. In fact, simple Graphite Reactors, built on the Stagg Field Reactor model, would be a far more practical tool for producing weapons grade nuclear material.

Lead Cooled Reactors, although potentially useful as breeders, have not finished their development. Two of the seven Soviet Lead Cooled Reactors are known to have experienced coolant system accidents. This type of reactor might be expensive to develop and construct. Therefore not enough is know about its' technology to judge its' usefulness as a nuclear proliferation tool.

It is impossible to determine how much a commercial Molten Salt Reactor would cost because none have yet been built. Scientists say that Molten Salt Reactors have lower material requirements and potentially, lower labor requirements than conventional reactors. The superior safety features of Molten Salt Reactors are expected to save money in reactor construction because the reactors themselves will require less redundancy. Normal operating features, incidentally, produce nuclear safety. Molten Salt Reactors can easily be sited underground saving construction money. They can be placed in salt mines, caves, and other underground facilities; saving money on containment costs. Thus Molten Salt Reactors may be less expensive than conventional nuclear power plants.

Pers Peterson believes that flaws in gas cooled Graphite Reactors can be corrected by use of molten salt coolants. This actually offers a very attractive short term nuclear concept because it combines already tested technologies. Such reactors can seemingly be built at low costs. I recently talked with Rod Adams and he advocated gas cooled Graphite Reactors. Given the state of my vision, I am not able to read the backup literature needed to compare gas cooled Graphite Reactors and Molten Salt Cooled Graphite Reactors. Both technologies would be highly safe and would offer significant proliferation prevention advantages.


SteveK9 said...

Russia is moving ahead on both lead- and lead/bismuth-cooled reactors:

L.T. said...

I am very very glad to see you back!

Anonymous said...

Vary happy to see you back Charles.
Failing eyesight really sucks.


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