in , , , ,

New Nuclear Fuel Can Be Here Even Faster Than New Reactors

New nuclear fuel could move global nuclear power forward much faster than new nuclear reactors.

The nuclear industry has been focusing on new reactor designs to address a variety of issues like climate change, backing up renewables, and replacing fossil fuels with a reliable baseload alternative. 

This is great and will certainly be part of any long-term solution. But new reactors will take some time to become common enough to make a real difference. This is especially true in emerging countries where energy poverty must be addressed soon in order to eradicate global poverty and its evil stepchildren war and terrorism. Of all human activities, poverty has arguably the worst effect on the environment.

But existing reactors can jump forward much quicker by using new types of advanced nuclear fuels.

A variety of new nuclear fuels are being developed to address existing and new generation reactors, including being accident tolerant, being longer lasting, being cheaper, providing more energy power, providing some recycling of previous fuel, providing easier refueling, being easier to store and dispose, and proliferation resistant.

An example of an advanced fuel innovation is Clean Core Thorium Energy’s (CCTE) fuel to addresses several of these issues at once. Called Advanced Nuclear Energy for Enriched Life, or ANEEL, their fuel combines thorium (Th) and HALEU (High Assay Low Enriched Uranium) to address cost, proliferation and waste. There is no reprocessing involved with this fuel.

Thorium is about three times more abundant than uranium on Earth and can be extracted readily from seawater.

Natural uranium is only 0.7% uranium-235 (U-235), which splits easily. The rest is U-238, which does not. It has to be enriched to around 5% U-235 in order to maintain a continuous chain reaction in most nuclear reactors. The exception is the CANDU (Canada Deuterium Uranium)/PHWR (Pressurized Heavy Water Reactor) reactors which use natural uranium and heavy water (D2O – Deuterium is hydrogen with one neutron in its nucleus).

However, it has long been known that higher levels of U-235 enrichment will provide more energy per mass of fuel, provide longer life for the reactor core, will allow smaller plant sizes, and give a higher burn-up rate for nuclear waste.

The world’s existing fleet of light water reactors (LWRs) use fuel enriched to about 5% U-235. But many advanced reactor concepts require HALEU, which is enriched to a higher degree – between 5% and 20%. CANDU/PHWR reactors can especially benefit from HALEU.

Above 20% enrichment is considered highly enriched and not acceptable for international civilian applications.

The aforementioned ANEEL fuel is a proprietary combination of Th and HALEU, with much less U-238 than ordinary fuel, less than 20% compared to over 94% used in LWR. The bulk of the fuel is a Th matrix driven by U-235 as a fissile driver by providing sufficient neutrons for continued fissioning.

Th-232 captures a neutron and converts to U-233 which is also fissile and begins providing more neutrons and more energy. At the same time, U-238 captures a neutron, converting to Pu-239 which also fissions, almost as fast as it’s created. 

With all this fissioning going on, the burn-up rate in the ANEEL fuel is high, providing more energy in the reactor from the same amount of fuel. In fact, ANEEL’s burn-up rate of over 50 GWd/t, is so much more than the 7 GWd/t rate of CANDU/PHWR current natural uranium fuel, that the reactor only needs about seventh of the amount of fuel over its life, translating into significant savings and benefits in operations, fuel and waste management costs.

Additionally, thorium and the resulting higher burn-ups lead to stronger proliferation resistance throughout its life cycle caused by deep burning of Pu. That increases the amount of Pu-240 and Pu-242 that breeds into the fuel, which are neutron poisons to the uncontrolled chain reactions needed for a nuclear weapon.

CANDU/PHWRs generally use natural uranium (0.7% U-235) oxide as fuel, so they need a more efficient moderator (the material that slows or moderates the speed of the neutron so it hits the next nucleus at the right speed to split, or fission, it). In this case, these reactors use heavy water (D2O). 

Unlike LWRs, CANDU/PHWR reactors don’t have to be shut down to refuel due to their design, and can be refueled at full power. After 150 days of initial operation in the current smaller CANDU/PHWR reactors (200-300 MWe), eight natural uranium bundles, weighing about 15 kg, have to be replaced each day for the rest of the reactor’s operating life of 60 years. 

But with an ANEEL fuel bundle, weighing approximately 10.65 kg, after 1,100 days of initial operation, only one such bundle on average would be replaced for the rest of the reactor’s life of 60 years, leading to over eight times less waste and the benefits as described.

Similarly, a 37 PIN natural uranium-fueled 600 MWe CANDU/PHWR, would require 348,000 fuel bundles over 60 years. With same 37 PIN ANEEL-fuel bundles the 600 MWe CANDU/PHWR, would require only 61,500 ANEEL fuel bundles over the same 60 years. This would translate to about $2 billion savings towards the fuel cost, direct disposal of spent fuel and the operational costs over the 60-year life of a reactor.

Thus, there is an opportunity to harvest such benefits by deploying ANEEL fuel in the CANDUs/PHWRs around the world that are planned for refurbishment, in which reactor life would be increased by another 30 to 40 years. This combined with the higher fuel burn up of ANEEL fuel reduces the waste by over 80% – less spent fuel means less refueling, less cost, less fuel handling and less volume to dispose.

The ANEEL fuel is a perfect example of an advanced fuel designed to maximize the advantages of our existing reactor fleet, specifically CANDU/PHWRs. Additionally, such Th-based fuel concepts can be adopted for existing light water reactors or the small modular reactors (SMRs) now under development.

It’s about time we used Th to help U power a green and sustainable future.

What do you think?

Top CI/CD misconceptions, explained

AI Is Not Going To Replace Writers Anytime Soon – But The Future Might Be Closer Than You Think