Another Monday Message Board. Post comments on any topic. Civil discussion and no coarse language please. Side discussions and idees fixes to the sandpits, please.
I’m now using Substack as a blogging platform, and for my monthly email newsletter. For the moment, I’ll post both at this blog and on Substack. You can also follow me on Mastodon here.
John Quiggin 
End the dream of nuclear power
The Iran crisis calls for a formal end to the broken dream of civilian nuclear power. A global treaty should be adopted, committing the international community to a phaseout of nuclear reactors for power generation. The treaty would also end all research and development on them, apart what whatever is necessary to ensure the safety of existing reactors, waste disposal, decommissioning and medical applications. The argument rests on two incontestable propositions.
1. Civilian and military nuclear technologies are inextricably linked. Nuclear weapons can be made using either uranium 235 or plutonium as the explosive, as in the Hiroshima and Nagasaki bombs respectively. Plutonium is produced by irradiating uranium in a nuclear reactor. A variety of reactor types will do. Since it is a different element from uranium, plutonium can be extracted from the irradiated material fairly easily using chemical methods. Uranium bombs need highly enriched uranium, with about 90% of the 235 isotope. Uranium from the mine is only 0.7% U-235, the majority being less radioactive U-233.
The isotopes are the same element chemically, so uranium enrichment is a laborious mechanical process. Uranium hexafluoride gas is fed into a high-speed centrifuge. The rapid spinning drives the 1% heavier U-235 preferentially to the outside. One of two outlet pipes exports slightly enriched gas, the other slightly impoverished. By connecting large numbers of centrifuges in stacks, you can enrich to any desired level: typically 4% for power reactors, 90% for a bomb. SFIK the same centrifuges are used over the whole range. This means that an enrichment stack is inherently dual-use. A civilian enrichment plant can readily be converted to a military one.
The exception here is that is possible to build a reactor without enriching the uranium fuel beyond what comes out of the mine. The Canadian CANDU reactors do just this. https://en.wikipedia.org/wiki/CANDU_reactor They are technically successful but commercial failures from their low efficiency. They do exist. Google: “The largest CANDU reactor is located at the Bruce Nuclear Generating Station in Ontario, Canada. It consists of eight reactors and has a total net output capacity of 6,288 MWe, making it the largest operating nuclear power facility in the world based on its reactor count.” However, no commercial CANDU reactors are currently under construction. Like other types, CANDU reactors cam always be used to make plutonium.
2. Civilian nuclear reactors are a waste of money. John Quiggin has written extensively on this so I need only summarise. Conservative investment bank Lazards give a range of LCOEs of $141-220 per Mwh, against $50-131 for firmed solar and $70-157 for firmed wind in the USA. https://www.lazard.com/media/uounhon4/lazards-lcoeplus-june-2025.pdf The nuclear costs are speculative as very few plants are currently under construction there. The industry and its fans continue to lobby for SMRs. No designs for these have been certified, history strongly suggests that the cost and timetables cited will be greatly exceeded, and the time to large-scale deployment is so far in the future as to make them irrelevant to the energy transition. A formal abandonment of civilian nuclear power would save money.
I therefore propose a Nuclear Power Phaseout treaty. It would express and underline a global consensus that nuclear is a technology we no longer need, that presents inevitable risks of the proliferation of nuclear arms.
My NPP comes too late to be useful in the current Iran crisis. However, I suggest a thought experiment. Suppose such a treaty were already in force. It would have sent a message to the Iranian people that a civilian nuclear power programme is a mirage that has no useful part in Iran’s energy future. Since the government insists that its nuclear programme is not aimed at a nuclear bomb, it should be abandoned. If it is not, the regime’s dangerous hypocrisy and forked tongue is exposed. I submit that such a result would have been helpful, and could be even more so in the future.
James Wimberley: – “Civilian and military nuclear technologies are inextricably linked.“
Yep. Note that nuclear weapons were produced BEFORE civilian uses were implemented.
James Wimberley: – “Nuclear weapons can be made using either uranium 235 or plutonium as the explosive, as in the Hiroshima and Nagasaki bombs respectively.“
Fissile isotopes are isotopes of certain elements that can undergo nuclear fission when struck by a neutron, releasing energy and more neutrons, potentially leading to a chain reaction. Uranium-235, Plutonium-239, and Uranium-233 are the most important fissile isotopes.
Naturally occurring uranium is composed of three major isotopes:
Uranium-235 (²³⁵U) is the only naturally occurring fissile isotope (in any appreciable amount).
Plutonium-239 (²³⁹Pu) is artificially produced in nuclear reactors through neutron capture by fertile isotope Uranium-238.
Uranium-233 (²³³U) is artificially produced by irradiating fertile isotope Thorium-232 with neutrons.
Critical masses:
See Introduction of Thorium in the Nuclear Fuel Cycle: Short- to long-term considerations, Table 9.1.
James Wimberley: – “Uranium hexafluoride gas is fed into a high-speed centrifuge. The rapid spinning drives the 1% heavier U-235 preferentially to the outside.“
Nope. ²³⁸U is slightly heavier than ²³⁵U. Was that a typo?
James Wimberley: – “The industry and its fans continue to lobby for SMRs. No designs for these have been certified,…“
There are no ‘factory-built’ small modular reactors (SMRs), but small reactors (i.e. IAEA’s definition is >20 up to and including 300 MWₑ net capacity) have been built. Some recent examples include:
• Russia’s AKADEMIK LOMONOSOV-1 & -2 floating twin small reactor project is rated at 2x 32 MWₑ net capacity, commencing full commercial operations on 22 May 2020;
• China’s SHIDAO BAY-1 (SHIDAOWAN-1) twin reactor project, with two 250 MWₜₕ High-Temperature Reactor-Pebble-bed Modules (HTR-PM) together driving a single steam turbine generating 200 MWₑ net, commencing full commercial operations on 6 Dec 2023.
The Canadian Nuclear Safety Commission (CNSC) and the Province of Ontario gave approval on 8 May 2025 to Ontario Power Generation (OPG) to begin construction of the first GE Hitachi BWRX-300 reactor, a 300 MWₑ water-cooled, natural circulation SMR, at the Darlington Nuclear Generating Station in Clarington, Ontario.
James Wimberley: – “A formal abandonment of civilian nuclear power would save money.“
Good luck with overcoming the vested interests…
James Wimberley: – “Since the government insists that its nuclear programme is not aimed at a nuclear bomb, it should be abandoned.“
IAEA Director General Grossi’s Statement to UNSC on Situation in Iran, dated 20 Jun 2025, included:
No civilian reactors require enriching uranium to 60%. Only military applications require enrichment to that level. Enrichment to that level already accomplishes over 90% of the work needed to bring natural uranium to weapon-grade.
Uranium fuel enrichment classifications include:
It’s unfortunate that one of the aspects to Trumps Bunker Buster Bombs is that being nuclear armed buys you peace from the US. I expect that Iran will now pull out all stops to deliver the US that message.
Another aspect is that there is no amount of intelligence that will convince a US President to not act – its the alternative truth/vibes/instincts that pushes their buttons.
I should add that between Trump and Putin, any previously existing trust or agreement between sovereign states is now worth zero, or almost Trump talks about doing a deal, making a deal, between X and Y, but its all just prattle – his accountability is zero as is his respect and loyalty to allies.
Geoff M: Thank for the technical details, and especially the correction on U-233 and U-238. However you don’t need to have an expert understanding of nuclear science to follow my argument. Deference to experts is in part what got us into this mess.
There has to be some good news out there;
Roger_f: it’s quite a bit more than a hope that Chinese coal-burning has peaked. I posted earlier that the series on thermal generation from the Chinese National Bureau of Statistics show a respectable 4.31% decline from Q1 2024 to Q1 2025. Pig iron production – which burns metallurgical coal – languished at a 1.24% increase. I infer that total emissions from coal fell: and since gasoline production fell 6.54%, it’s likely that all emissions did. This is not conclusive. I’m not up to tracking down all the uses of coal in Chinese industry and buildings, and I leave out gas (not a big part of energy supply). It all could theoretically be noise or spin. However it is quite enough to establish a Bayesian prior. It’s up to the doomsters to prove me and – more important, Lauri Myllyvirta – wrong.
Q2 data will become available near the end of July. I’ll post an update.
Looking forward to this, James
AEMO have some interesting data on renewable energy; currently we are running on a 60:40 ratio of renewables to non renewable sources. Surprisingly roof top solar is now the dominant source of energy.
https://aemo.com.au/energy-systems/electricity/national-electricity-market-nem/data-nem/data-dashboard-nem
AEMO gave the breakdown of yesterday 6pm supply in Victoria during a cold snap; wind, battery and hydro = 43%
The amount of investment in Australian renewable energy continues to increase, with $12.7B spent in 2024 and close to $20B projected for 2025. This investment wasn’t phased by the 2025 election, it’s obvious that the LNP was all hot air.