Ian Bradford: The push to Net Zero with wind and solar is futile. We must invest in nuclear as soon as possible.

Nuclear reactors come in many different shapes and sizes. Most are large enough to power major cities and small reactors are being developed to complement them. Most use water to cool their cores, while other use gas or metals. About 425 reactors globally, ranging in size from 30MW to 1700MW are water cooled. There are two types of water cooled reactor: light water reactors, (which use normal water), and heavy water reactors. These are further divided into a boiling water type and a pressurised water nuclear reactor. Below is a diagram of a typical boiling water type.

The nuclear reactions take place in the enclosed container on the left. The walls of this container are very thick. The heat generated by the nuclear reaction heats water in the vessel inside the container and turns it to steam. The steam drives a turbine coupled to an electric generator. The electric generator then transfers electricity to the transmission lines. Meanwhile, the steam passes through the turbine into a condenser. Warm condenser water goes into a cooling tower and is emitted as steam. So that white smoke coming out of cooling towers is just hot water or steam. The water lost has to be replaced by cold water from a source such as a lake, ocean or river.

The two types of nuclear reaction

The type used in all nuclear power stations at present is a fission reaction. In this type of reaction one isotope of an element often U235 is bombarded with neutrons and this causes it to split into isotopes of two different elements. Now let me explain what an isotope is. Most elements have isotopes. Normally an element has equal numbers of protons, and neutrons. When the number of neutrons is different from normal we have an isotope of the element. Below are the isotopes of Hydrogen

Normal Hydrogen-the most common form, has no neutrons. Deuterium is the form of Hydrogen used in heavy water.

How we represent elements and isotopes

If we use Helium as an example, it might be represented like this: 

The bottom number is the atomic number- the number that gives its position on the table of elements. So it is number 2 on the Periodic Table. The top number gives the mass number which is the total number of protons and neutrons. This tells us that there is only one neutron since the number of protons remains unchanged at 2.

So here is a typical fission reaction. 

Uranium 235 is an isotope of the common form of Uranium 238. U 235 is radioactive and is used in reactions because it can undergo fission. An element such as radium which naturally emits neutrons is used and the neutrons strike the U235 and cause it to split into two separate isotopes of Barium and Krypton. The combined mass of Barium and Krypton is less than that of the Uranium. But mass has not been lost, it is converted into energy using the famous Einstein equation E=mc2 where m is the apparent mass loss and c is the speed of light.

235 g of Uranium loses 0.0001834 Kg in a fission reaction. 1 kg of Uranium loses 0.00078 Kg in a fission reaction.

I have gone through the full calculation but won’t include it here.

In the end, 1kg of Uranium in this fission reaction gives 7.02 x 1013 Joules of energy. Expanded out that’s 70,200,000,000,000 Joules, or a bit over 70 thousand billion Joules.

Compare that to a Kg of coal, which gives about 30,000,000 Joules or 30 million Joules.

So a Kg of Uranium gives about 2million times the energy of a Kg of coal.

Now notice that neutrons are produced in the reaction as well. These go on to collide with more Uranium and so the reaction proceeds. It you just let it run then you have a chain reaction. But in a power station it is controlled by the insertion of rods, often Cadmium, and these absorb the neutrons preventing further collisions. The energy output can be controlled by how many Cadmium rods you insert. So the energy output can be adjusted according to the demand for electricity. You can’t do this with wind or solar.

The other type of nuclear reaction is a fusion reaction. In this type of reaction two isotopes are made to join and become one. To do this very high temperatures or pressures are required. The problem at present is containment of the two isotopes in a “vessel” which will withstand very high temperatures. Magnetic fields are being tried to contain the isotopes. A large fusion reactor is being built in France-the ITER reactor. Thirty five nations are participating in this endeavour. However, it may be some time before fusion reactors are used for our power sources.

Advantages and disadvantages of both types:

Both types take up a relatively small area of land compared to the many acres wind and solar take up. Solar farms often occupy 50 acres or more and it is usually flat land once used for farming. No birds, bats, or whales are killed by nuclear power stations, and they emit no pollution. The push towards fusion reactors is important. The end products of fusion reactors don’t pose much of a problem. These products are Helium, an inert gas found in the atmosphere, and Tritium which is radioactive and emits beta articles. But the good news is that the half life of Tritium is only 12 years. That means that after 12 years half of the radioactivity has gone, and after a further 12 years half of the remainder radioactivity has gone and so on. So storage is not a problem as after a relatively small number of years radioactivity will be so low the Tritium can be handled. Fusion is not based on a chain reaction so no nuclear accident is possible. If there is a problem the reaction simply stops. The fuel cannot be used for bombs as a fission reaction is needed to detonate.

On the other hand, nuclear waste from fission reactors has been a storage problem. The half life of the final products may be hundreds of thousands of years. There is a very low probability that a chain reaction may run amok, leading to the production of much heat and a nuclear meltdown. The storage problem looks like it is disappearing. Recycling of the waste is now becoming more common. Waste is now called spent or used fuel. The US for example, generates about 2000 tonnes of spent fuel per year, but this actually quite small compared to the amount of energy produced. Spent nuclear fuel can be recycled to make new fuel and by-products. More than 90% of its potential energy still remains in the fuel even after 5 years of operation in a reactor. There is enough energy in the nuclear waste in the US to power the whole country for 100 years. The technology to turn nuclear waste into energy is known as a nuclear fast reactor.

IAEA Director Rafael Mariano Grossi states that it is time to focus on fast reactors. They shrink the environment footprint on the waste while significantly extracting more energy from the fuel. They can be a bridge to even safer and more efficient nuclear power, providing sustainable clean energy for generations. Fast neutron reactors operate without the need for a moderator such as water or graphite to sustain the fission reaction and can extract up to 70 times more energy from fuel than existing thermal reactor designs. Used fuel can be reprocessed and reused.

To date liquid sodium has been the coolant of choice for FNR’s. Sodium has a high boiling point and can extract more heat . This enables smaller generators to produce more energy and generate more electricity. Its disadvantage is that chemical a reaction with air and water takes place if leaks occur. Back in the past this has been a problem. To overcome this, other liquid metal coolants are now being developed. Lead-Bismuth Eutectic was used in Russian submarines in the 1960’s and is now being developed as another option for power reactors along with Lead. These coolants are chemically inert on contact with air or water, simplifying the heat transfer system. Gas coolants such as Helium and molten salt mixtures are also being studied.

The early years of development were plagued with largely technical issues but these have been largely overcome and there is now much renewed interest in their development.

Moving to fourth generation fast neutron reactors will change the outlook dramatically, and it means that not only used fuel from today’s reactors but also the large stockpiles of depleted uranium become a fuel source. Uranium mining will become less significant.

Reprocessing of the spent fuel involves the recovery of Plutonium and unused Uranium. This gains about 30% moreenergy from the original Uranium. So far, France, Russia, Japan, the UK, and India have facilities to recycle, and the US is just beginning.

Through recycling, 96% of used nuclear fuel, comprising 95% Uranium and 1% Plutonium, can be repurposed into new nuclear fuel. The remaining 4% is sealed in glass and placed in metal containers for about 300 years until it decays to the original low level of radioactivity of the Uranium first mined. This is a great deal better than the hundreds of thousands of years if the waste is not recycled. But there’s even more good news, a company Orano is working to find uses for the remainder 4% which contains useful materials such as Krypton, Strontium 90, Americium-241 and rare earth lanthanide elements. There are isotopes to fight cancer, for other medical uses, isotopes for industrial use, for national security, for space bases and even some non-radioactive isotopes have great value.

There are three advanced reactor systems in the pipeline. Companies, Oklo, TerraPower, and Westinghouse are working on fast reactor technologies.

The Sodium- cooled fast reactor.

Generation 1V nuclear reactors are being developed through an international co-operation of 14 countries including the United States.

This sodium cooled fast reactor uses liquid sodium as a coolant instead of water. This allows for the coolant to operate at higher temperatures and lower pressures than current reactors – improving the efficiency and safety of the system. The SFR also uses a fast neutron spectrum, meaning that neutrons can cause fission without having to be slowed down first as they are in current reactors. This could allow SFR’s to use both fissile material, or spent fuel from current reactors to produce electricity. 

The very high temperature reactor

This is cooled by flowing gas and is designed to operate at high temperatures that can produce electricity efficiently. Very high temperature reactors offer impressive safety features and are easy to construct and affordable to maintain.

Molten salt reactor

Molten salt reactors use molten fluoride or chloride salts as coolant. MSR’s are designed to produce less fuel and produce shorter lived radioactive waste than other reactor types. They have the potential to remove waste products and add fresh fuel without lengthy refuelling outages. MSR’s can use waste from other reactors.

Interest in FNR’s is now reviving in Europe and the USA both through collaborative projects. Further research and development is on three types- the gas filled fast reactor, the lead cooled fast reactor and the sodium cooled fast reactor.

Thorium based nuclear power

Advocates believe Thorium is key to developing a new generation of cleaner, safer nuclear power. Molten salt reactors are well suited to Thorium fuel. Thorium exists in nature in a single isotopic form. It is slightly radioactive and decays very slowly. Thorium itself is not fissile and so is not directly usable in a thermal neutron reactor. It is however fertile, and by absorbing neutrons it can end up as Uranium 233, which is an excellent fissile fuel material. Thorium fuels therefore need a fissile material as a driver so that chain reaction and thus a supply of surplus neutrons can be maintained. U233 can be used as a driver. A standout feature of Thorium reactors is their passive safety features. Unlike Uranium reactors which use solid fuel rods, thorium reactors operate with a liquid fuel mixture at normal pressure, significantly reducing the risk of meltdowns and other catastrophic events. These reactors also produce less toxic and shorter lived radioactive waste, simplifying long term disposal challenges. The chain reaction needs an initiator material to begin fission, with the reaction ceasing immediately upon its removal. The ideal material to supply these vital initiating neutrons is the waste from conventional nuclear fission. So it is an efficient machine to destroy nuclear waste.

Benefits of Thorium

It is abundant – at least three times as abundant as uranium. India has the most Thorium, but next door neighbour Australia also has a large quantity. It is difficult to make an atomic bomb from a Thorium reactor’s by-products. Thorium is not fissile like Uranium, so Thorium nuclei will not split apart and explode. There is less nuclear waste. This eliminates the need for large scale or long term storage. The radioactivity of the stored waste drops down to safe levels after somewhere between one and few hundred years compared to perhaps hundreds of thousands of years. Once started up a breeding reactor needs no other fuel except Thorium because a breeding reactor makes most of its own fuel. It is very efficient. One tonne of Thorium can produce as much energy as 200 tonnes of Uranium or 3,500,000 tonnes of coal. The reactors have failsafe measures. Liquid fluoride Thorium reactors are designed to be meltdown proof. A fusible plug at the bottom of the reactor melts in the event of a power failure or if temperatures exceed a set limit, draining the fuel into an underground tank for safe storage. Mining is safer than mining Uranium. Thorium’s ore is called Monazite. Mines are open pit which require no ventilation.

In August 2021 China announced the completion of its first experimental Thorium based nuclear reactor. Built in the Gobi desert in the country’s north, the reactor will undergo testing over the next few years. If the experiment proves successful Beijing plans to build another generator capable of generating electricity for more than 100,000 homes. Other countries are also starting to get in on the act. There are seven types of nuclear reactor into which Thorium can be introduced as a nuclear fuel.

At COP28 over 20 countries pledged to triple the world’s nuclear energy capacity by 2050.

While the New Zealand Government may have short term plans for more electricity, all MP’s should be looking further ahead and considering future power demands. It should be clear to all now that wind and solar will not meet power demands in the future, nor will they take us to net zero. (which is a waste of time anyway.) Fast neutron reactors have a lot going for them. They take up much less land than the wind and solar monstrosities. They don’t emit carbon dioxide. That will satisfy the climate alarmists. They have the ability to recycle used fuel, and hopefully in the near future all used fuel will be recycled. There will be plenty of used fuel available. In saying that, one consideration could be to build a conventional water cooled plant as well as the fast reactors. The waste from the conventional plant could be used to run the fast reactors. New breeder reactors using Thorium, show huge promise. There are several options. New Zealand needs to move on from its outdated non-nuclear stance and come into the modern world. BUT A DECISION NEEDS TO BE MADE SOON OR WE WILL HAVE BLACKOUTS. The demand will soon exceed the supply.

Ian Bradford, a science graduate, is a former teacher, lawyer, farmer and keen sportsman, who is writing a book about the fraud of anthropogenic climate change.