Nuclear Monitor #910
Jan Willem Storm van Leeuwen, member of the Nuclear Consulting Group
A nuclear power plant is not a stand-alone system. To function properly it needs a complex of technical and industrial processes. Nuclear energy is generated by fissioning uranium-235 nuclei in a nuclear reactor. From where comes that uranium?
Often people are inclined to talk solely about the nuclear reactor when discussing nuclear power; the other processes are not visible at the site of an operating nuclear power plant. The chain of activities needed to enjoy nuclear power is comparable to a common, daily chain of activities. Getting a nice meal implicates a chain of activities: gathering the ingredients, cooking the meal, setting the table, enjoying the meal, clearing the table, washing the dishes and cleaning the kitchen.
Application of nuclear energy has many aspects: technical, social, financial, political, military and aspects concerning safety and health of millions of people. This complexity may be a factor why policymakers are often not well informed about nuclear power.
Construction of new nuclear power plants
Experience in France, UK and Finland indicates that the costs of a new nuclear power plant may be as high as 10 bn euro/GW and that the construction time may become 15-20 years. Remarkably, the construction costs of nuclear power plants kept rising since the construction of the first nuclear power plants in the 1960s: the absence of a learning effect.
CO2-free?
Many policymakers are considering nuclear power as the best solution to decrease the emission of CO2 into the atmosphere and halting the global warming. The contribution of nuclear power to the world energy consumption is about 2%. Assuming that the generation of nuclear power does not emit CO2, which is not true, the nuclear contribution to the reduction of the world CO2 emission and the reduction of the global warming would be no more than 2%.
Fission of uranium-235 nuclei in the reactor is the only process in the chain of processes vital to the generation of usable energy from uranium that does not produce CO2, all other processes do, directly or indirectly.
The construction of one nuclear power plant consumes more than 1 million tons of concrete and 0,2 million tons of steel. No CO2?
Green?
The only green energy source humankind has at his disposal is the sun. Look at the biosphere: a green layer of highly ordered materials around the globe. These green ordered materials came into being from dispersed materials: CO2 in the air and water with dissolved minerals. Ordered materials have a low entropy, dispersed materials have a high entropy; entropy is a measure of dispersion, of chaos. Lowering the entropy of an amount of material, that means increasing the order in that material, is only possible by a unidirectional flow of energy. Energy from the sun reaching the surface of the Earth is a unidirectional flow.
Conversion of the potential energy from mineral energy sources (fossil fuels and uranium) into a unidirectional energy flow is thermodynamically coupled to the generation of entropy: dispersion of heat and materials, some of which are radioactive. One of the dispersed materials is CO2. Because the conversion of potential energy from mineral energy sources occurs within the biosphere all its unavoidable entropy effects remain in the biosphere: the consequences are deterioration of the biosphere and global warming. The entropy coupled to the energy generation in the sun remains in the sun and its surrounding space. Thanks to the unidirectional energy from the sun the Earth has a green biosphere, with a low entropy. That is green energy.
Energy cliff and CO2-trap
Extraction of uranium from the Earth’s crust consumes energy and is accompanied by the emission of CO2. The content of uranium in the still available uranium ores is lowering in the course of time. Mining companies always use the richest available ores first, because these deliver the highest return on investments. So the remaining ores are poorer, have a lower grade. Consequently in the course of time the extraction of one kilogram uranium consumes more energy and emits more CO2. This phenomenon occurs also with the extraction of other metals, but uranium is the only metal used as energy source.
If the world nuclear power production remains at the present level, the extraction of 1 kg uranium from the Earth’s crust in the 2070s is expected to consume as much energy as can be generated from that kilogram. This is called the energy cliff. When this extraction is fuelled by fossil fuels, the emission of CO2 per kilowatt-hour of the contemporary nuclear process chain will be as high as the specific CO2 emission of fossil fuelled power plants. This is called the CO2-trap.
Radioactivity
A unique aspect of a nuclear reactor is its generation of human-made radioactivity. One nuclear power plant produces each year an amount of human-made radioactivity equivalent to the amount generated by the explosion of more than 1000 Hiroshima atomic bombs. Radioactivity is not visible nor can be smelled, its presence can be demonstrated only by special equipment.
A nominally operating nuclear power plant discharges into the air and/or into the cooling water several radionuclides, important ones are: tritium (H-3, radioactive hydrogen), carbon-14 (radioactive carbon) and krypton- 85 (radioactive noble gas krypton). Both tritium and carbon-14 accumulate in the food chain.
Tritium is biologically dangerous. Tritium atoms can be incorporated in DNA molecules. By radioactive decay of the tritium atoms the DNA molecules get damaged; damaged DNA molecules may cause serious disorders. Krypton-85 can be uptaken via inhalation, it has a high lipid solubility. Its radioactivity is damaging in living tissue. In addition krypton- 85 causes disturbing effects in the atmosphere.
Health risks, millions of people are involved
The consequences of contamination by radiation and/or radioactive materials become not immediately noticeable, but after weeks, months or years. A direct causal connection between a radioactive contamination and a specific disorder is rarely provable. With epidemiological studies in large population groups correlation can be demonstrated between exposure to radioactivity and health. No epidemiological studies on the initiative of the nuclear industry or governments have been performed after the disasters of Chernobyl and Fukushima.
Epidemiological studies in Germany and France, by medical institutes, proved that the occurrence of cancer among children younger than 5 years increases as they live nearer a nominally operating nuclear power plant.
Storage of radioactive materials
Radioactive waste produced during more than seven decades of nuclear power is still waiting for definitive storage in geological repositories. The radioactive materials, remaining radioactive for tens of thousands of years, are stored in vulnerable above-ground facilities. Safe storage in deep geological repositories is still not the practice anywhere in the world. As far as known Sweden and Finland made the most progress in constructing such repositories, 500 meter deep in granite. Constructing a geological repository plus storing the waste in it may cost more than the construction of a new nuclear power plant.
Safety
Globally the chance of occurring severe nuclear disasters increases with time. Three Miles Island, Chernobyl and Fukushima will unlikely be the last nuclear disasters. During the Chernobyl disaster, the amount of humanmade radioactivity dispersed into the environment was less than the production of one year. Vulnerable for severe failures are not only nuclear reactors, but also the transport of highly radioactive materials, the temporary storage of spent nuclear fuel elements and reprocessing plants. A nuclear disaster can proceed silently, contaminating large areas and hundreds of thousands of people without notice.
One factor that certainly enhances the chance of a nuclear disaster is the inevitable ageing of the construction materials by spontaneous processes (Second Law of thermodynamics). A second certain factor is the increase of the quantities of temporarily stored radioactive materials. Unpredictable factors are terrorism, military actions, natural disasters, accidents caused by human failure.
Small Modular Reactor (SMR)
SMRs are defined to have a power in the range of 30 – 500 MW, instead of the present large nuclear reactor (1200 MW). The SMR is claimed to be safer, cheaper to build and would produce less waste. These claims are unproven. The SMR concept may be similar to a military reactor used in ships and submarines and operates with highly enriched uranium. At this moment the first commercial SMR exists only on paper.
Thorium
The use of thorium instead of uranium is sometimes named as the future of nuclear power. Thorium is more abundant in the Earth’s crust than uranium and a thorium reactor is said to produce less dangerous radioactive waste. Thorium is a radioactive metal and is not fissionable. To use it as energy source, thorium has to be converted into fissile uranium-233 by means of neutron radiation in a nuclear reactor.
Use of thorium as a commercial energy source implicates the construction and the flawless operation of a breeding cycle. In addition to severe technical difficulties, fundamental problems prevented realisation of a functioning thorium-uranium-233 breeding cycle. Development of such a breeding cycle in the USA has been discontinued decades ago.
Uranium-plutonium fast breeder
Scarcely mentioned in these days is the uranium-plutonium fast breeder, which would produce electricity “too cheap to meter”. The U-Pu breeder would fission an amount of uranium nuclei from a kilogram of natural uranium 60-100 times the amount that is fissioned in a conventional reactor, which can fission not more than 0.5% of the nuclei in natural uranium. In seven countries the development of the U-Pu breeder system has been discontinued, only three (Russia, India, China) are still pursuing this line. The total investments in breeder technology by Western countries is estimated to be about 100 billion dollars. The reason of the discontinuation may be found in the confrontation with the same kind of technical and fundamental problems as with the development of the thorium-uranium-233 breeder system.
The scientific foundations of the facts mentioned in this article and the accompanying scientific references can be found on the website https://www.stormsmith.nl/
