Kairos and TVA partner to build demonstration pebble-bed nuclear reactor

Kairos and TVA partner to build demonstration pebble-bed nuclear reactor
The Hermes reactor uses pebble-bed fuel and fluoride salt coolant
The Hermes reactor uses pebble-bed fuel and fluoride salt coolant
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The Hermes reactor uses pebble-bed fuel and fluoride salt coolant
The Hermes reactor uses pebble-bed fuel and fluoride salt coolant

The US Tennessee Valley Authority (TVA) and Kairos Power have announced a new agreement to build Kairos' Hermes low-power demonstration molten-salt cooled, pebble-bed reactor at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee.

With the pressures of climate change policies and official opposition to fossil fuels in the US, nuclear power is looking increasingly attractive, but it isn't a matter of building more of the huge pressurized water reactors that have dominated the American nuclear industry since the 1950s. Currently, agencies like the TVA, which generates 40 percent of US nuclear power, are more interested in advanced and unorthodox plant designs, like small modular reactors and pebble-bed reactors like Hermes.

In a conventional reactor, the fuel is in the form of pellets of enriched uranium or plutonium set inside of fuel rods placed in a geometric array interspersed with control rods to form the core of the reactor that is immersed in water. The fuel rods sit close enough together to start the nuclear reaction, the water moderates or slows down the neutrons spewed by the splitting atoms to maintain the reaction, and the control rods keep the reaction from going out of control and causing a meltdown.

In a pebble-bed reactor, the rods are replaced with tennis-ball-sized spheres made of layers of enriched nuclear fuel and graphite, which acts as the moderator, and clad in ceramic. Thousands of these spheres or pebbles are poured inside the reactor, where they set off and sustain the nuclear reaction at high temperatures without the need for control rods. In most pebble-bed reactors, the core is usually cooled by a gas like helium, nitrogen, or carbon dioxide. Though the concept of the pebble-bed reactor has been around since 1947, and the principle is simple and self-regulating, there have been a number of technical hurdles to overcome, so the reactors that have been built have all been research or prototype designs, but no fully operating plants have been constructed.

According to Kairos, Hermes is a demonstrator reactor for developing the technologies that will go into advanced future reactors for actual service. Instead of gas, it uses molten fluoride salts. Where water has a temperature range of 100 °C (180 °F), from melting to boiling, and can suddenly flash into steam under the right conditions, fluoride salts have a range of over 1,000 °C (1.800 °F), which allows them to transfer huge amounts of heat at ordinary pressures. In addition, they're chemically stable, can operate without bulky and expensive high-pressure containment structures, and, in the event of a reactor failure, they can keep the core cool by natural circulation.

When up and running, Hermes will put out 140 MWE at an operating temperature of 585 °C (1,085 °F) using pebbles containing fuel enriched to 19.75 percent.

"We look forward to collaborating with TVA, and drawing upon the well-versed knowledge and expertise of their team," says Mike Laufer, Co-Founder and CEO of Kairos Power. "Kairos Power and TVA have a shared commitment to improving people’s quality of life and pursuing innovation through advanced nuclear that provides reliable, clean energy for the future."

Source: Kairos Power

There is still the problem of nuclear waste and very high decommissioning costs. Solar, wind etc with battery storage will beat nuclear in the marketplace.
Good to see development of high density energy generation systems. They will be needed to backup sporadic wind and solar power. However, for the present natural gas is still #1.
Nuclear waste problem only exists because a bunch of naive/ignorant SJWs put their nose where it does not belong & prevented construction of kind of nuclear reactors which could use used nuclear fuel from regular reactors as fuel, by claiming such reactors would cause nuclear proliferation!
Except, very clear evidence shows not building such reactors never prevented countries like N Korea & Iran!!!

Just imagine that, if back in the 70s for example some people claimed that all cars, trucks are inefficient & causing lots of pollution & so we should stop using them! & so whole world quit on them & started using horse carriages! & we today were still using horse carriages, instead of autonomous electric cars etc!
That is fascinating, is this similar to the Thorium / Salt reactor technology?
The "problem" of nuclear waste is vastly overblown. All the high level nuclear waste from all the reactors in the U.S. since the first one came online 70 years ago would fit on a football field stacked 20 feet high. And that waste can be reprocessed into fuel or consumed in breeder reactors that reduce it to far less waste and with a much shorter half-life, on the order of hundreds of years instead of tens of thousands. It is a manageable problem but the nuclear alarmists have, like everything else about nuclear power, convinced the low-information public that it's an apocalypse. Nuclear power is by far the most efficient, safest, and cleanest, and most reliable large-scale power production yet invented. Solar and wind have huge drawbacks and are unlikely to ever replace utility-scale base load power plants. And they are expensive when you add in the cost of having base load power plants to provide power when they don't.
@aksdad I agree, solar/wind is incredibly inefficient and unreliable (you don't always have sun and the wind changes constantly). nuclear generation is a relatively mature tech and the waste management/reuse isn't such a big deal, unfortunately uneducated, emotionally over-reactive snowflakes cry that it'll kill the planet etc and sadly woke politicians listen to them.
Philip Argy
All technological developments that will provide safe and reliable baseload power need to be pursued unless and until their practical viability is shown to be non-feasible. Clever Aussie technology like hydrogen boron fusion could eventually make everything else obsolete so it's worth watching:
Rann Xeroxx
Solar and wind only beats nuclear when artificial market conditions are created by government to manipulate choice. Even environmental conditions are ignored like the mass killing of endangered birds and bats, the light pollution of massive wind farms, the massive clearing of trees and land to make right of ways for power lines to get solar and wind from remote ideal areas to areas of usage, etc.

All of these have their place but they are niche at best. Nuclear is the best answer for future energy use, period.
Paul Bedichek
You never have to handle nuclear waste,once the pebbles have gone through the reactor 5 or 6 times and most of the energy extracted,they are transfered to casks and these are eventually buried,no handeling of the spent fuel,all the actinides are trapped within the rugged pebbles.
This vastly decreases the cost of waste mangement the spent fuel is in it's funal form never to be reprocessed, it can simply be buried