- Nuclear Power generation fueled by Thorium (atomic no. 90)
- A nuclear reactor consumes certain specific fissile isotopes to produce energy. Uranium-233, transformed from thorium-232, derived from natural mined thorium is used as nuclear reactor fuel
2) Energy Generation
a. Uranium-233 as a nuclear fuel
- Thorium (Th-232) is not itself fissile so is not directly usable in a thermal neutron reactor. However, it is fertile and upon absorbing a neutron will transmute to uranium-233, which can be an excellent fissile fuel material.
b. Fission chain reaction
- The fission of uranium-233 doesn't release enough neutrons to kick off chain reactions
- To use uranium-233(derived from thorium) as a nuclear reactor fuel, more neutrons must be pumped into the reactor to keep it going
- Mix the thorium with transuranium nuclide (the chemical elements with atomic numbers greater than uranium (atomic no. 92) such as enriched uranium 235, uranium 238, or plutonium)
- Sub-critical reactor coupled with high intensity proton accelerator called accelerator-driven systems (ADSs): High-energy accelerators or cyclotrons can produce neutrons by spallation. The neutrons produced by spallation would cause fission in the thorium based fuel, assisted by further neutrons arising from that fission
Science Writer Richard Martin : Thorium could provide a clean and effectively limitless source of power while allaying all public concern-weapon proliferation, radioactive pollution, toxic waste, and fuel that is both costly and complicated process.
- Uranium itself is fissile material: Once nuclear fission starts, it produces the massive concentrations of radioactive materials and the huge amount of heat. Cooling system is required for cooling them down. When the accidents and disasters such as earthquakes occur, they can cause failures in cooling systems and cause meltdowns→nuclear disaster
Ex) Fukushima nuclear accident
- As thorium can't split to make a nuclear chain reaction (is not fissile on its own), reactions could be stopped in case of emergency such as blackout.
- ThorCon liquid-fuel reactor, newly designed by Martingale Inc in USA, is a complete system of power generation module. There are four barriers between the fuel salt and the atmosphere. ThorCon is walk-away safe
- Hazardous nuclear waste production rate is a thousand times less than uranium.
- Zero CO2 emission
- In thorium based nuclear reactor, 100% of natural thorium can be used as a fuel. An accelerator-driven system including fast reactor can be used to burn transuranium nuclide contained in the used fuel from a conventional nuclear reactor.
- The radioactivity of the resulting waste also drops down to safe levels after a few hundred years, compared to tens of thousands years needed for current nuclear waste to cool off.
d. Nuclear Weapon nonproliferation
- Thorium reactor’s plutonium production rate would be less than 2% of that of a standard reactor.
- It is easy to build nuclear weapon because conventional uranium reactor produce nuclear waste containin enough plutonium ← the real reasons of using uranium over thorium in cold war-era.
e. Efficiency (1ton of Thorium vs. 250tons of Uranium): One ton of thorium can produce as much energy as 250tons of uranium, or 3,500,000tons of coal(Dr. Carlo Rubbia). Liquid fluoride thorium reactor(LFTR) can generate 1GW of electricity for 1 year with 1 ton of thorium
- Conventional reactors (Uranium based nuclear reactor): 250 tons of uranium per year for 1GW plant are required. From them only 35 tons of enriched uranium (containing 1. 15 tons of U235) are burned at conventional reactors and generate about 35 tons of spent nuclear fuel (waste).
- Thorium-based nuclear reactor (liquid fluoride thorium reactor): Since all natural thorium can be used as fuel, expensive fuel enrichment process is not needed. LFTR use only one ton of thorium per year for 1GW plant and produce 1ton of radioactive waste. Within 10years, the 83% of them are stable and can be sold and 17% of them go to geologic isolation for 300 years.
- According to MIT’s future of nuclear power 2009 analysis, most of the cost of nuclear electricity is actually the cost to construct the nuclear reactors (capital cost).
- The construction cost of thorium-fueled power plants is from five to seven times cheaper than that of traditional uranium reactors: Building a 1-gigawatt uranium plant today costs about $1. 1 billion. Building a 1-gigawatt thorium plant will cost only about $250 million or less, because meltdown concerns can be tossed out the window.
- Current operating costs, ignoring fuel costs, is a tenth of that of uranium reactor: While a 1-gigawatt uranium plant require about 500people and costs $50 million/year, thorium fueled reactor (liquid fluoride thorium reactor) costs $5 million/year.
- ThorCon liquid-fuel reactor, newly designed by Martingale Inc in USA, can generate electricity at 3cents/kWh which is cheaper than gas or coal.
3. Brief History
1) First Development
a. 1965~1968 an experimental molten salt reactor at Oak Ridge National Laboratory
- In the 1960s, uranium-based reactors were built to produce electricity, during that period, the U. S. Government built an experimental molten salt reactor using U-233 fuel, the fissile material created by bombarding thorium with neutrons.: The reactor, built at Oak Ridge National Laboratory, Operated critical for 15,000hours from 1965 to 1969
b. In 1968, the thorium-based reactor had been successfully developed and tested.
- Novel laureate and discoverer of plutonium, Glenn Seabory Publicly announced to the Atomic Energy Commission of which he was chairman, that the thorium-based reactor had been successfully developed and tested.
Policy of Nixon era : In 1973 US Government had made the decision to kill all of thorium research.
- Government scientists in the 1960’s developed a smaller and potentially safer form of nuclear power using cheap and abundant fuel, only to have the program mothballed and kept secret for decades.
- All thorium related research, which had been ongoing for twenty years at Oak Ridge National Laboratory,was stopped: The reasons were that uranium breeder reactors were more efficient, the research was proven, and byproducts could be used to make nuclear weapons.
- For the benefit of military uses, the safe thorium based nuclear power was sacrificed
- Carlo Rubbia, Italian Particle Physicist, generated 1MW of Electricity using proton cyclotron at the Paul Scherer Institute (PSI) in Zurich.
b. In 2013 Feasibility Testing of the thorium as a nuclear fuel
- In 2013, private norwegian company, Thor Energy began to produce energy at Halden test reactor in Norway using thorium as nuclear fuel: This test provide unique information necessary for qualifying this new fuel material for commercial use in current reactors.
b. Bill Thesling ,the Cleveland-based Energy from Thorium Foundation CEO
- Safety advantage over today’s high pressure reactors: In the thorium molten-salt reactor, thorium dissolved in a high temperature solutions of fluoride salts. It can't melt down because it’s already molten, so the concept of a meltdown is not even at play.
e. Professor Bob Cywinski, University of Huddersfield
- We need nuclear energy, nuclear power helps to combat climate change, emitting a tiny fraction of the carbon produced by fossil fuels. Misgivings over safety and the waste produced by conventional uranium-fuelled nuclear reactor can be addressed by the use of thorium.
- Jiang Mianheng, son of former leader Jiang Zemin visited the Oak Ridge labs and obtained the designs after reading an article in the American Scientist two years ago(2011) extolling thorium. He concluded that a molten salt reactor may answer for China's energy shortage and national security concern. He is spearheading a project for China’s National Academy of Science with a start-up budget of $350m. Over 140 PhD scientists have been working full-time on thorium power at the Shanghai Institute of Nuclear and Applied Physic.
- In 2014 China Government declared “War on Pollution” and decided to concentrate on developing thorium nuclear powers: The Chinese Academy of Science set up an advanced research centre in Shanghai in January 2014 with the aim of developing the world’s first industrial reactor using thorium molten-salt technology. A team of scientists in Shanghai had originally been given 25 years to try to develop the world’s first nuclear plant using thorium as a fuel. In March 2014, China Government reduced the original goal of creating a working reactor from 25years down to 10 by 2024 as China Government’s interest was changed from solving energy shortage to the smog crisis.
b. India: The leader in thorium reactor development. World’s first thorium reactor Designed.
- India refused to ratify the Nuclear Non-Proliferation Treaty (NPT) and excluded from trade in nuclear plant and material for 30years by Nuclear Suppliers Group (NSG). While India's uranium resources are limited due to trade bans, India has huge reserves of thorium.
- World's first thorium based nuclear reactor designed: In February 2014, the first look of design and prototype of the advanced heavy water reactor(AHWR) presented and slated for operation in 2016. Because of its inherent safety, researchers expect that thorium based nuclear reactors could be set up within populated cities like Mumbai. Dr. Sinha, chairman of Atomic Energy Commission predict that, the first megawatt of electricity would be generated within 7~8 years.
- From 2009 researchers at the Belgian nuclear research centre, SCK-CEN and EU have been designing for constructing the multi-purpose hybrid Research Reactor MYRRHA consists of a proton accelerator and reactor.
- According to a SCK-CEN schedule, construction could start in 2022, with commissioning the following year, and MYRRHA entering full operation by 2025.
- MYRRHA is now conceived as a flexible irradiation facility, able to work as an accelerator driven (subcritical mode) and in critical mode
- Using $250million in federal research funds to revive ORNL (Oak Ridge National Laboratory) research.
- U.S.Department of Energy is collaborating with Oak Ridge National Laboratory on molten salt reactor using molten fluoride salts as primary coolant and thorium as nuclear fuel
- Collaborating with China on thorium-based nuclear power designs using molten-salt reactor
- In 2015, Martingale Inc. announced the newly designed ThorCon Liquid-fuel reactor generating for cheap, reliable, CO2-Free electricity. Production can start by 2020
- Terra Power, a start-up spin-off from Intellectual Ventures, and backed up by Bill Gates, has been developing its traveling wave reactor concept since the company was founded 6 years ago. A working prototype has not, however, yet been produced. Last week, at an event at the Oak Ridge National Laboratory, TerraPower revealed officially, that it is seriously looking into another advanced nuclear reactor concept: the molten salt reactor.
- Japan's International Institute for Advanced Studies(JIAS) is researching molten salt reactors that use liquid fuel.
- MYRRHA project: Collaborating with EU
- The UK is playing a key role in an international project to develop a new type of nuclear power station.
- Integral Inherently Safe Light Water Reactor (I2S-LWR) Project : To design I2S-LWR, cambridge team is considering the project not just from the perspective of fundamental nuclear reactor physics but also focusing on achieving high fuel-to-power conversion efficiency and cost effectiveness.
- SAMOFAR(Safety Assessment of the Molten Salt Fast Reactor) Project
- TU-Delft presented and officially announced a European Thorium MSR Project, SAMOFAR due to start in August 2015
- SAMOFAR Consortium consists of 11 participants from both science and industry
- The grand objective of SAMOFAR is to prove the innovative safety concepts of the MSFR by advanced experimental and numerical techniques, to deliver a breakthrough in nuclear safety and optimal waste management.
- The SAMOFAR project focuses on the MSR as a "self-breeder", producing its own fuel from cheap and abundant thorium without generating a surplus of proliferation sensitive fissile material, like all other reactors in the world do.
- Samofar is focused on fast reactors, which are more efficient than conventional light-water reactors and can breed fissile elements from nuclear waste.
- The researchers will build experimental laboratory facilities—not, at least for the next few years, an actual working reactor—to test the geometry of the freeze plug, the coatings of vessel and pipe materials, the behavior of the liquid fuel during circulation and draining, and other key safety metrics.
- In 2013, President Park and Bill Gates discussed about energy innovation. Bill Gates called for Korea’s attention in developing the next-generation nuclear reactor in order to efficiently deal with public safety concerns, nuclear waste and malfunctions.