Australia is about to run out of electricity

by Geoffrey Hudson

The AEMO Draft 2024 Integrated System Plan has a graph of the planned power output from coal:

A common view is that wind and solar will replace the coal fired power being lost, and the electricity grid will continue to supply power day and night reliably. The prospect of a cloudy windless week challenges this view. Storage of electricity is a challenge we have not yet met.

AEMO forecasts battery growth to grow seven fold within this decade but while batteries can generate large amounts of power, they can only supply it for a short period. Total Australian battery capacity has increased to nearly 2.5GWh[1] recently[2] but output at 1 GW could only be managed for 2 ½ hours. Multiply by 7 if you are happy with the AEMO forecast and you get 17.5 hours. The Snowy Hydro 2.0 system[3] is expected to provide 2.2 GW and with 350 GWh capacity, it can maintain that for nearly a week, but the gap is 30 GW, and in a week of cloudy windless days, power shedding would be unavoidable. We need tens of Gigawatts of power coming from an on-demand source to support a switch from coal and gas, support for electric vehicles, and maintenance of the grid.

As the AEMO Draft 2024 Integrated System Plan states in section 4.3 “With most coal forecast to withdraw by 2034-35, the race is on for new utility-scale generation both to replace that coal capacity and then provide for tomorrow’s industry and transport”.

The failure to win that race will mean continued operation of coal fired power plants. No state government can survive repeated grid failures of significant length. The recent extension of the contract with the Eraring plant[4] is evidence of this. The plant can generate 2.88 GW, i.e. more than Snow Hydro 2 and all the batteries combined.

I believe there is a way to solve this problem which, while it requires extensive engineering, does not require novel processes. It is Nuclear Power. The trouble is, most people oppose the use of any nuclear reactions for anything. It is unfortunate that lack of knowledge is a major contributor to this opposition. Most people are unaware of the radiation their body receives from the food they have eaten, and are also unaware of the Banqiao dam failure[5] which killed more than 100,000 people, making hydroelectric power the most dangerous power known to man.

Did you know that 4,000 nuclear particles are released inside you every second from the Potassium you have eaten? This radiation is not man-made, nor even from space. It is a remnant of the formation of the earth itself. About one part in 10,000 of natural Potassium is the isotope 40K (Potassium 40) which is radioactive with a half life of 1.2 billion years[6] so when the earth was formed about 4.5 billion years ago[7], the fraction of Potassium which was 40K was about 16 parts in 10,000. We humans need Potassium and absorb and secrete it to maintain about 140 gms for a body weight of 77 kg, i.e. a concentration of about 0.2%[8]. If the level falls below this some illnesses such as kidney stones appear, and if the level is too high, other health problem can arise, especially in people whose kidneys are not fully functional. In nearly 90% of the 40K decays, an electron with an energy of more than 1,000,000 electron volts[9] is released. This will destroy several cells which need to be replaced, so you are losing about 10,000 cells per second just from the Potassium you have eaten. Some people have found this to be depressing. I say you should rejoice in the fact that your body has devised all the mechanisms to ensure you do not even notice this loss of cells. You have more than 200,000 million cells and losing a paltry 860 million per day is easily managed. The fact that you can read this is proof that you can survive more than 10,000 cell deaths per second, so when people say a single radioactive particle can kill you, ask them why you are still alive.

Many opposed to nuclear power are aware of the accidents at Chernobyl[10] and Fukushima[11]. While the flood at Fukushima killed many thousands of people, the evidence based reports show that less than 100 people died from radiation at Chernobyl and none at Fukushima. When compared with the 100,000 deaths from flooding in the Banqiao dam failure event, these losses are insignificant.

No other known technology which does not consume fossil fuels, can supply “on demand, weather proof” electricity. We are backed into a choice: Nuclear Power, or global warming from burning coal. Some progress will be made with batteries but not soon enough to reach the targets which have been promised.

Public opposition to nuclear power is regarded as the most challenging issue faced by plans to shut down coal fired power stations. The next most important 3 issues are the capital cost of building nuclear power stations, the length of time to build them, and what to do with the radioactive waste. This paper attempts to address these issues.

The AUKUS arrangement shows the way. There were no protests against it. The nuclear reactors will not be anywhere near voters, and the radioactive waste need not be dealt with for several years. The federal government has already passed changes to laws[12] to allow Australia to own nuclear powered submarines and most people didn’t even know that.

Now imagine a quite different submarine containing power generation equipment instead of weapons, able to run without refuelling for 5 years instead of 33. Have it manufactured and then loaded with Uranium and tested in Australia, and then travelling to a shallow water location about 1 kilometre from shore where it is connected to an undersea power cable. After 5 years it is replaced with another similar vessel while it returns to the ship yard for refuelling. The location will be like:

The proposed characteristics of this submarine are listed in Appendix A.

Public Opposition to Nuclear Power

The contrast between the public reaction to nuclear power generally, and the reaction to the AUKUS deal is likely to arise from several issues:

  1. The submarines will be Not In My Back Yard. Remoteness from where people live reduces opposition. There will be no carrying of radioactive materials across our roads or railway lines to support these vessels.
  2. The radioactive waste is kept in the submarine.
  3. Nuclear accidents are most unlikely, and if one occurred it would not contaminate any Australian land or air we would be likely to breath.
  4. Decommissioning of a portable nuclear reactor can also be done far away from voters.

Most of these advantages also apply to ships. However a ship containing a nuclear reactor and steam turbines would need to be kept close to a power cable, and probably would be safest tied to a dock. The dock could support protestors or saboteurs. Not a problem in Siberia, but significant in Australia. Leaving the ship at sea presents dangers of storms and tsunamis, and ship collisions. A submarine anchored to the sea floor below the draft of even large ships is less likely to be affected by storms, or earthquakes. It cannot release radioactive gases to rain down on Australia.

The problems faced by nuclear power stations built on land are listed in Appendix B. The key factors in favour of power submarines are that they do not require allocation of land, and that they are portable.

The key question to ask is: “Is there a way to deliver nuclear power to Australia which will generate less protest than a submerged vessel a kilometre or two from the coast which will depart from that site with all its nuclear waste in a few years?”

The Time to Construct

The track record for building nuclear power stations shows that many years are required between commitment of funds and delivery of electricity. Permits need to be obtained. Regulatory authorities need to be satisfied that risks to the land and surroundings are minimized. A bespoke design must be completed and approved. Construction and then the testing of that construction follows and can be complex. The push for Small Modular Reactors (SMRs) is an attempt to reduce the time and cost, but on-site assembly, initiation and testing will still be required. The experts who first get the reactor to go critical must travel out to the site.

A self-propelled vessel with a diesel backup generator can be manufactured in a ship yard anywhere in the world in a few years, and then travel to another new ship yard to have the nuclear fuel loaded, and the full system tested, and then move to the chosen site in a matter of months. The new Australian facility need only install the nuclear reactor and the primary heat exchangers and pumps. A reactor with 20 cubic metres of molten salt would be likely to weigh less than 100 tonnes and could be lowered into a submersible vessel with a removable top.

Construction Cost

A key question is how much will such a submarine cost. The first reaction of many is that submarines are way too expensive. Using ship building metrics indicates quite lower costs.

Submarines are more expensive than ships, but much of that expense is in the state of art weapons, detection systems, and systems to prevent detection. The ability to descend below 100m of depth where the pressure is 10 Bar, also adds to the cost. The vessel proposed here would have a maximum depth of 100m and need not travel at great speed -10 km/hr would be sufficient. With appropriate automation a crew of 6 is expected to be sufficient, but a lifeboat/shuttle submersible would be required for crew rotation.

To estimate the cost, it is broken into 3 parts: the basic vessel, the turbines, generators and transformers which would be standard units such as those used in coal fired power plants, and the nuclear reactor. It should be noted that the usual pressured water reactors (PWRs) can only produce steam at about 350°C because the critical temperature of water[13] is 374°C. This requires special turbines able to manage drops of water, and produces less power per unit of heat supplied than those commonly used in coal fired power stations. To overcome this problem and provide enhanced safety, this proposal would use Molten Salt Reactors which can supply heat at up to 600°C.

The easiest cost to estimate is that of the turbines, generators and transformers. Since they will be those used in coal fired power stations, the cost of those stations can be used as a guide. The typical cost of a coal fired power station is $1 per watt, and the vessel proposed could deliver 400 MWe, the cost of the steam turbines, generators, transformers and heat exchangers might be expected to be less than $400M.

To estimate the cost of the vessel which contains these components and the nuclear reactor is more difficult. Rules of thumb for ship building indicate costs of $1 to $10 per kilogram of total weight. The Russian power barges[14] weigh 21,500 tonnes, so at $10 per kg, the shell for the vessel envisaged here would cost $215M.

Adding a molten salt reactor powered by low enriched Uranium able to generate 1GWth ought not to cost more than another $400M. The molten salt is mainly Lithium Fluoride which costs about US$5 per gram[15] . Twenty cubic metres would weigh about 50,000,000 gms costing US$250M, but with Graphite moderation, a significantly smaller volume is likely to be required. The Hastelloy steel costs less than US$100 per kilogram, and about 10 tonnes would be required costing US$1M. The other components are likely to add up to another $100M.

The total cost is thus estimated at $1000m which is $2.50 per watt, significantly less than the $5 per watt estimated for existing nuclear power stations. The major reason this is smaller than that for existing land based plants, is that the permission costs are limited to the Federal Government so the documentation of the design and the redesign to accept regulatory standards is reduced, and the design will be standardised and repeated many times. The financial benefit of the supply of Tritium[16] and other valuable waste products would compensate for that cost, but $2.50 per watt for on-demand power is regarded as competitive. Australia alone would need 75 such vessels to replace the 30,000 MWe from coal fired power stations planned to be decommissioned in the next 10 years, so mass production would be appropriate.

Nuclear Waste

The key problem of nuclear waste is the long-lived Actinides[17], particularly Plutonium. If these are removed and used as fuel in another reactor, the remaining waste, particularly Caesium and Strontium, have half-lives less than 31 years and therefore lose 99.9% of their radioactivity in 310 years. This makes the problem tractable, but does require reprocessing of the waste, and therefore changes to the Environment Protection and Biodiversity Conservation Act. This will be required for AUKUS but the Virginia class submarines use highly enriched Uranium and can run for 30+ years without waste removal. The proposed vessels would need waste removal after 5 years of operation, but reprocessing would follow several years when the most radioactive waste would decay, so it would probably not be required before 2040.

The reprocessing of nuclear waste is a hazardous chemical process. France has a reprocessing plant in La Hague[18] which extracts Plutonium and Uranium from the used fuel rods from Pressurised Water Reactors (the most common kind), so that they can be used to produce new fuel rods. The process involves many steps and significant amounts of nitric acid.

Molten salt reactors can use a simpler reprocessing system which involves injection of Fluorine gas into the molten salt. This can produce Uranium Hexafluoride and Plutonium Hexafluoride which are gases at the appropriate temperature and pressure. These gases bubble out of the molten salt and can then have the fluorine separated for reuse.

In short, there are means to separate the long lived Actinides from waste and use them in nuclear reactors so that only the short lived waste needs to be stored. We need only choose to establish the right kind of chemical facility and optionally do research to find better chemical processes to perform these separations.

Initial Steps

There are several steps which are required to progress this plan:

Establish a University Department of Reactor Physics

A University should be persuaded to establish a department of Reactor Physics. This should train people in Neutronics, the science of managing the creation and usage of neutrons. Computer systems to predict neutron production and consumption exist and need to be established. In addition, high temperature chemistry is a vital part of molten salt reactors and the ability to research in this area is vital, either in a Physics department or a Chemistry department. Universities should be invited to submit proposals to establish this expertise.

Design the Submarine Shell

The design of a single system including everything except the molten salt nuclear reactor, and the initial heat exchanger which transfers heat from the reactor salt to a mediator salt with minimum radioactivity, should be developed. The list of features shown in Appendix A should be included. The major components such as steam turbines, generators and pumps should be chosen from those currently available for purchase.

Obtain a Quotation to Build that Submarine Shell

The design should be submitted to a variety of ship building organisations with a request for quotation on the cost of supply. This will determine whether this plan can continue.

Obtain Estimates for the cost of the Reactor

There are at least 4 companies developing molten salt reactors. Each should be contacted with a view to obtaining a cost estimate for a 1GWth molten salt reactor to be included in the submarine. The ability to supply power for at least 3 years without refuelling or maintenance will be an important factor.

Review Locations for the Shipyard

A search for the location of an appropriate shipyard in Australia for these vessels should be made. A dry dock facility with remotely controlled cranes and robot arms to service a submarine after a period of operation would be required. There would be advantage in sites which have a rail line separated from other rail lines so that rail cars carrying nuclear waste can be transported away from the dry dock in safety.

None of these actions involve large expense when compared with the $350,000M planned for AUKUS. Talk to your local member of parliament and ask them to read this article.

Appendix A – Key Features of the Proposed System

Power

The proposed power output is 400 MWe supplied by two 200 MW generators. This will require a reactor to generate about 1000 MWth (of heat). The power system will include two identical turbines, generators, and condensers to provide backup.

Depth

The proposed maximum depth for the vessel is 100 metres. This will be sufficient for the craft to be below the hulls of all surface vessels at low tide to minimise the chance of collision.

Mobility

The complete power station except for cables connecting it to the grid will be mobile. The reactor, the turbines, generators and transformers, and all radioactive material is contained in a vessel able to move once disconnected from the grid cable. It will be able to move itself, but only at low speed (say 7 knots).

Limited Fuel

The vessel will not have any continuous chemical processing system and can only produce power for a limited number of (probably 5) years. It is to be replaced with another system after this time, unless there is no further need for power.

Molten Salt

The reactor should use Molten Salt rather than solid fuel pellets in tubes in pressurized water. This eliminates the need for the pressure tank required for pressurized water reactors, and the containment shield needed to manage a leak in that pressure tank. It also means that the steam turbines manufactured for coal fired power plants can used, saving space and expense.

Sea Floor Location

The system should rest on poles a few metres long which then are supported by the sea floor. This will secure the vessel against sea currents, and the reaction to the movement of cooling water. The sea depth should be between 60m and 80m below low tide.

Limited Crew

A small crew (estimated at 6 people) will supervise the power station. The main activities will be changing pump speeds and control rod positions via remote control to adjust the output power, and reacting to any faults.

Snorkel

In order to supply fresh air for the crew and (if required) the backup diesel engine, a snorkel will extend to the sea surface. Radar and TV cameras will be mounted to allow observation of any approaching vessel.

Lifeboat/ Shuttle

A small vessel able to operate below the surface and on the sea surface and able to carry the crew will be included. This will be able to dock with the submerged power station for crew changes and to act as a lifeboat should difficulties arise.

Openable

The system needs to be opened to allow specialised remotely operated equipment to install fuel, remove waste molten salt, and maintain highly radioactive components. The top of most of the vessel must be able to be removed so that turbines, generators, transformers, reactor pumps, molten salt, and some fixed components of the reactor can be installed and removed. This allows a single set of the specialised remotely operated equipment to be used for many such systems, reducing the cost of that part of the operation.

Appendix B – Disadvantages of Ground Based Power Stations

Protest

People living near the proposed location, and even many from further away, will protest the site in the belief that it poses a danger to their health. The submarine plan removes the location for a protest.

Permission

Permission from all parts of Government, Federal, State and Local Council will be required. Because the cost of this permission is so high (The Desalination plant in Victoria incurred legal costs of $16M before building could start), it will be attractive to have a small number of large plants. Gaining permission may take years and involve changes of government. The submarine plan reduces this to a Federal Government permission which has already been granted for AUKUS.

Bespoke

Because each piece of land is different and the desirable plant size is likely to be different from others, a bespoke design of the system is likely to be required. Standardisation is difficult when the number of closely similar plants is small. Each new design must gain approval from regulatory agencies, which incurs further delay and cost. The submarine plan allows standardisation.

Remote Construction

Nuclear power plants are generally remote from large populations. This means living quarters for those involved in the construction are commonly required. Higher wages are commonly needed to attract people to go to a remote site for a few years. While use of Small Modular reactors can help, the buildings, fencing, signage, and grid interconnection are local developments. The submarines can all be built, fuelled and maintained in one location.

Fuel Transport

Once the reactor building is ready, fuel must be transported over land to the site. This adds a risk to the operation, and could easily stimulate protest.

Waste Removal

When the fuel has sufficient usage, the concentration of fissile elements is low enough, and the concentration of daughter nuclei is high enough, the fuel must be removed from the reactor using remotely operated mechanisms. These mechanisms are also required for repairs in the highly radioactive parts of the station. The cost of providing these elaborate remote operation systems is high and they are used rarely, and are themselves difficult to maintain, so they need to be designed for maximum reliability.

Waste Storage

If the waste fuel is to reprocessed, it must be stored at the site for several years, and then transported over land on its way to a waste reprocessing site. Even after several years it will be many times more radioactive than the fuel originally supplied. The submarine plan allows a single location to be used.

Decommissioning

Decommissioning a land based nuclear power plant involves measuring radiation at each point in the plant, separating radioactive components from others, and transporting those radioactive components to some repository.

  1. GWh= Gigawatt hour = 1000 MWh = 3,600,000 Megajoules ↑
  2. https://www.energyinnovation.net.au/article/report-finds-a-significant-surge-in-australian-battery-capacity-in-2023 ↑
  3. https://www.dcceew.gov.au/energy/renewable/pumped-hydro ↑
  4. https://www.nsw.gov.au/media-releases/nsw-government-secures-two-year-extension-to-eraring-power-station ↑
  5. https://www.britannica.com/event/Typhoon-Nina-Banqiao-dam-failure ↑
  6. See https://en.wikipedia.org/wiki/Isotopes_of_potassium ↑
  7. See https://education.nationalgeographic.org/resource/formation-earth/ ↑
  8. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/#h18 ↑
  9. https://en.wikipedia.org/wiki/Potassium-40#:~:text=Potassium%2D40%20undergoes%20three%20types,1.31%20MeV%20and%20an%20antineutrino. ↑
  10. https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident ↑
  11. https://en.wikipedia.org/wiki/Fukushima_nuclear_accident ↑
  12. Defence Legislation Amendment (Naval Nuclear Propulsion) Act 2023 (C60) of 04 Jul 2023 to 21 Aug 2023 ↑
  13. https://socratic.org/questions/56058db1581e2a2b0c50f3d7 ↑
  14. https://en.wikipedia.org/wiki/Russian_floating_nuclear_power_station, ↑
  15. https://www.msesupplies.com/products/mse-pro-lithium-fluoride-lif-99-999-5n-granules?variant=31731504185402 ↑
  16. The cost of Tritium is $30,000 per gram. ↑
  17. Actinides are elements with 89 or more protons including Uranium, Plutonium, Americium and Curium ↑
  18. See https://www.orano.group/en/unpacking-nuclear/all-about-radioactive-waste-in-france ↑