The Green Reactor: The LFTR and Green Chemistry

The Liquid Fluoride Thorium Reactor is considered a chemists reactor. As such its operations will probably be evaluated by the so-called 12 principles of green chemistry. The Wikipedia describes the 12 principles of green chemistry. According to the Wikipedia:

“the principles cover such concepts as:

* the design of processes to maximize the amount of raw material that ends up in the product;
* the use of safe, environment-benign substances, including solvents, whenever possible;
* the design of energy efficient processes;
* the best form of waste disposal: do not create it in the first place.

The 12 principles of Green Chemistry are:

1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.
2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.
3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
4. Use renewable feedstock: Use raw materials and feedstock that are renewable rather than depleting. Renewable feedstock is often made from agricultural products or are the wastes of other processes; depleting feedstock are made from fossil fuels (petroleum, natural gas, or coal) or are mined.
5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.
6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.
8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.
10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.
11. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.
12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

The LFTR conforms to the principles of Green Chemistry in many ways, first by
1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.
The fuel cycle of the LFTR is the LFTR is the thorium fuel cycle rather the Uranium fuel cycle of the Light Water Reactor. In order to produce the same amount of power produced by one ton of thorium in a LFTR, the Light Water reactor wastes 200 tons of depleted Uranium and over 18 tons tones of U-238 in the form of nuclear waste. Thus the LFTR is about 200 times more efficient that the LWR in its conversion of the materials found in nuclear fuel into energy. The materials that are left over after nuclear energy has been extracted from thorium are not waste, and indeed have many uses. Thus the LFTR performs the first principle of green chemistry.

2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.
The electricity produced by a LFTR is no more toxic than electricity from any other source. LTFRs produce some material byproducts. And some are toxic. Toxicity is, however, a function of concentration. In high levels of concentration, many common substances essential to life and good health, including common table salt, iron, vitamins A and D, chlorine, oxygen and even water are detrimental to life, but their absence is even more detrimental to life. If all toxic materials were removed from chemical use, modern civilization might well be impossible. If human beings are completely protected from every substance that it toxic, our lives would be impossible, quite literally. According to green principles, life itself has been poorly engineered, and needs to be redesigned. It should be noted that LFTR byproducts are far less toxic than the waste from LWR’s, and from coal fired power plants. The LFTR, if properly designed and operated, would not produce toxic plutonium, which is produced by LFTR. In the case of most byproducts, “green” chemistry can convert then into non-toxic forms in consumer products. In the case of radioactive byproducts, the very properties that make them toxic also make them valuable, for example the uses of radioisotopes in medicine. Radiation from radioisotopes, can prolong the shelf life of foods, and kill off undesirable microbes in human and animal waste, thus protecting the environment.

Thus the production of relatively small amounts of toxic materials by the LFTR does not automatically and need not lead to undesirable human and environmental outcomes, especially in an overall system that is governed by green principles.

Finally the LFTR can eliminate the discharge of CO2, which is toxic to the planet earth. In comparison, wind and solar generation systems. “Soft path” energy guru Amory Lovins, acknowledges the continued use of fossil fuels including natural gas, in future “green” electrical generation systems. Thus until the reliability and base load problems associated with renewable electric generation are solved, all renewable generation systems require the continued use of fossil fuel burning and CO2 emitting electrical generating plants, if reliable electricity is to be available on the grid. Thus renewables, in their present form, are toxic to life on the planet earth.

3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
While this is a lofty goal, it is also completely impractical, and indeed when applied to electrical production systems, this principle if systematically applied would make not only nuclear but also solar and wind generating systems impossible. Wind generating systems use large amounts of steel and cement. The manufacture of both produces a large amount of planet toxic CO2. Solar is metals intensive, and uses a large amount of glass, that requires heat that is produced by burning fossil fuels in its production. Renewables advocates have not indicated how they will remove CO2 from renewables building materials.

On the other hand reactors require far less steel and cement than wind, and require no glass and far less metals than solar generating facilities per amount of electricity generated. The LFTR uses less steel and cement in its manufacture than conventional reactors. Thorium and fluorides, the two principles material input into the LFTR, have already been mined, and are at present considered waste. Energy inputs into their extraction from existing mine tailings would be minimal. Further more, the LFTR can produce a great deal of electricity while consuming small amounts of thorium, and no fluorides. Fluorides are recyclable in LFTRs. At the very least,
the LFTR is a candidate for the title of least toxic electrical source possible.

4. Use renewable feedstock: Use raw materials and feedstock that are renewable rather than depleting. Renewable feedstock are often made from agricultural products or are the wastes of other processes; depleting feedstock are made from fossil fuels (petroleum, natural gas, or coal) or are mined.
This criterion is built on the confusion of sustainable and renewable. I received the following comment from donb on Nuclear Green yesterday:

With regards to sustainability, it strikes me that the “greenies” are stuck in the old paradigm of fossil fuels. In this old paradigm, the major sustainability concern is with the fuel, which is consumed in vast quantities, and thus becomes more scare and harder to extract as time goes on. The minor concern is with the materials needed to burn the fuel and use the energy. One of the results of this mindset is the less-than-critical examination of “renewable” energy sources such as wind and solar. These sources must be “good” because the fuel is inexhaustible (within the lifetime of the earth orbiting the sun).

The new paradigm that must be adapted is that with advanced nuclear (and renewables), the fuel is essentially inexhaustible. That being the case, we then need to look at the resources needed to harness the energy. Nuclear wins hands down due to its extremely high energy density, and the ability to produce energy on demand, not just when natural conditions allow.

Donb thus argues that nuclear fuel, unlike fossil fuels is inexhaustible in an practical sense. This viewpoint has received substantial support. Arguments that nuclear fuels are a limited resource have been found to contain numerous errors, and aappear to have never been published in peer reviewed scientific journals. Thus the case against the sustainable resource view of nuclear fuel does not appear to be strong.

5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.
Here again we have to ask how realistic such a principle is. Is it practical or even possible to produce all the chemicals we would chose to have, by limiting chemical processes to those which can be conducted with catalysts. Until this point is clarified, the Greenness of this principle is open to question.

6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
Not involved in MSR/LFTR operations.

7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.
Here again we encounter a conceptual problem with the so-called Principles of Green Chemistry. It is quite possible, with the LFTR to have an output of useful materials with a number of atoms that considerably exceeds the number of atoms in the original process materials input. The explanation is that thorium input atoms have undergone fission. However, most nuclear material from the thorium atoms is discharged from the LFTR process as useful materials. Much of the rest will be in the form helium, which is a potentially useful material

8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
No solvents are used in the LFTR, or in internal processing it fuel or the recovery of fission products.

9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.
In terms of EROEI the LFTR is quite possibly the most energy efficient electrical source ever devised.
In order to produce electricity the reactor must operate at far above ambient temperature but it does operate at ambient pressure, unlike Light Water Reactors.

10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.
It would appear that the LFTR produces little or no chemical waste. Material inputs into the process are largely accounted for in the output, or recycled into the reactor, radioisotopes output will break down to innocuous substances, most of which have uses.

11. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.
The formation of byproducts from the nuclear reactor is inevitable, the byproducts are almost all either desirable materials, or highly desirable materials, and properly managed they are very unlikely to produce pollution.

12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.
There is no potential for explosions or fire with LFTR technology. The LFTR possesses notable inherent safety features. Although leaks are unlikely, a system of fission product recovery and multiple containment barriers will prevent fission products from escaping to the environment if leaks do happen.

Conclusion: Significant questions have emerged from this discussion concerning the Green Chemical Principles. While the goals of preventing waste and pollution are undeniably laudable legitimate questions can be raised about the practicality of several of these principles. The problem of toxic chemicals would appear to be more complex than assumed by the principles. Finally the applicability of some of the principles to electrical generation in general and to the operation of the LFTR is questionable. The 12 Principles of “Green Chemistry” clearly are not canonical science and are unlikely to become so in their present form. However, from the viewpoint of its low materials input, high-energy output relative to energy input, lack of waste in materials output, safety and lack of environmental pollution as a consequence of its operation, the LFTR would seem to fulfill the objectives of Green Chemistry. The failure of the LFTR to fulfill all of the principles of Green Chemistry are thus due to the inadequate formation of some of those principles and/or the lack of applicability of those principles to the LFTR, rather than any failure of that reactor concept to meet green goals.

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