Thorium: The NASA Story TV - Guardian online - Nick Touran -
Apollo astronauts used plutonium RTG to power their science equipment. The MARS rover Curiosity is entirely powered by RTG. Thorium: The NASA Story, 2016
Exploring space requires energy. Energy to run experiments … For how long can plutonium power a mission? ibid.
The worldwide shortage of RTG fuel is a perpetual constraint on space missions. ibid.
‘We are looking at a nuclear reactor and they tend to be heavy.’ ibid. scientist
Three Mile Island, Chernobyl, Fukushima: these three accidents illustrate the need for a coolant with a higher boiling point that water. ibid.
Thorium: it’s not based on water cooling and it doesn’t use solid fuel. Surprisingly, it’s based on salt … Salts don’t have to be pressurized. ibid.
Chemically stable and non-reactive. ibid.
Tell me why it’s not the greatest thing since sliced bread? ibid. Sorensen
In a world increasingly aware of and affected by global warming, the news that 2010 was a record year for greenhouse gases levels was something of a blow.
With the world’s population due to hit nine billion by 2050, it highlights the increasingly urgent need to find a clean, reliable and renewable source of energy.
India hopes it has the answer: thorium, a naturally occurring radioactive element, four times more abundant than uranium in the earth’s crust.
The pro-thorium lobby claim a single tonne of thorium burned in a molten salt reactor (MSR) – typically a liquid fluoride thorium reactor (LFTR) – which has liquid rather than solid fuel, can produce one gigawatt of energy. A traditional pressurised water reactor (PWR) would need to burn 250 tonnes of uranium to produce the same amount of energy.
They also produce less waste, have no weapons-grade by-products, can consume legacy plutonium stockpiles and are meltdown-proof – if the hype is to be believed. The Guardian online article 23rd June 2011, ‘Don’t Believe The Spin on Thorium Being a Greener Nuclear Option’
Myths and Misconceptions About Thorium Nuclear Fuel:
Dear Internet, we need to talk about Thorium …
Thorium Misconception #1: Development of Thorium-based molten-salt reactors got cancelled because they coudn’t make bombs!
Thorium Misconception #2: Thorium reactors never need enrichment!
Misleading at best. When people say this, they tend to imply that Th-fuelled reactors are the only reactors that never need enrichment, which isn’t true. The nice thing about any breeder reactor (using Th-U or U-Pu) is that eventually they can become fissile self-sufficient, meaning they breed more (or equal) fissile material than they consume.
Thorium Misconception #3: Thorium reactors cannot make bombs!
Thorium Misconception #4: There’s more Thorium than Uranium, and that is really important!
This one is mostly true, but also partially false!
Thorium Misconception #5: Thorium reactors are the only ones that make waste that is safe in hundreds of years!
False: Undenatured Thorium cycles certainly produce fewer transuranic elements (Np, Pu, Am, Cm,+), which are the major dangerous nuclides in nuclear waste in the 10,000+ year timeframe. In fact, the long-term decay heat from Thorium-MSRs can be orders of magnitude lower than that from traditional reactors. However, this same capability exists in many other reactor concepts, including U-Pu fueled fast reactors with reprocessing. So, if someone says that MSR/LFTR waste is better than traditional LWR waste, they are correct. If they say Thorium is the only game in town that can reduce waste like this, then they are not correct.
Thorium Misconception #6: Thorium reactors and Molten Salt Reactors are the same thing!
Not Always: On one hand you can choose between a Th-U fuel cycle and a U-Pu fuel cycle. On the other hand, you can choose between a fluid fuelled reactor (like a MSR) or a solid fuelled reactor (like a LWR or a sodium-cooled fast reactor). Now, the Th-U cycle works really really well with MSRs, and that’s why they are often discussed together. There’s nothing wrong with this, but it’s nice to know what benefits come from which choice. The Th-U fuel cycle can be (and has been) used in solid fuelled reactors and the U-Pu fuel cycle can be (and has been) used in MSRs.
The attributes of a system that come from choosing a fluid fueled reactor include: the ability to have passive safety by draining the fuel into cooled storage tanks, online fission product removal, low/zero fabrication cost, low fissile requirement, low excess reactivity (since you refuel online)
The attributes that come from choosing the Th-U fuel cycle over the U-Pu cycle include: the possibility of thermal breeding (as demonstrated in the Shippingport LWR), the reduced production of minor actinides (see Misconception #5), allowing nuclear waste to be safer without aggressive reprocessing, and the ability to use the Thorium mineral base instead of the Uranium minerals (useful if your country has Th but no U. See Misconception #4). Dr Nick Touran, online article March 2014