My wife and I are concerned about the disposal of nuclear waste. In the event of more nuclear power stations in the UK, are we going to leave our descendants with a mountain of waste? What are the French doing about this problem?

Prof says . . .

You and your wife are right to be cncerned about the scale and nature of waste from any energy conversion process, including nuclear-fuelled electricity generation.

All electricity generating processes leave some waste – CO2 and water vapour from oil and gas combustion, mountains of spoil as well as CO2 and water vapour from coal, and tons of steel and concrete from wind turbines at the end of their lives (possibly 20 years), but I fully recognise your specific concern about waste from nuclear electricity generation because of the time-scale over which significant radiation could be emitted.

Before answering your questions in detail, I must say that judged on their records, British nuclear engineers design and operate the safest systems for nuclear-based electricity generation, fuel reprocessing and waste containment in the world.

The short answers to your questions are (i) no we are not going to leave our descendants with a mountain of waste and (ii) the French do much the same as we do and are considering the same options for the future.

Long answer: Nuclear Waste

1. It is important to appreciate that nuclear waste is NOT generated by nuclear electricity power stations. What is generated there (besides electricity) are spent uranium fuel rods which, after cooling at the power station, are sent by rail in sealed, impact-proof, containers to the reprocessing plant at Sellafield.

These containers have been tested among other ways by having a 90 mph train crashing broadside and head-on into them. The containers were found to be completely intact and leak proof among the debris of the two trains after the crash.

2. The spent fuel rods contain (1) mainly (95%) uranium 238 (which is NOT reactive), (2) unused uranium 235 (around 1.5%) which is reactive, (3) plutonium 239 (around 1% typically) which is also reactive and (4) about 2.5% of materials which have to be separated from the other components, before they can be re-used.

3. The reprocessing plant at Sellafield – one of only two such large-scale plants in the world (the other is in France) – separates out three component streams [(1)-(3)] from the returned fuel rods (which are going to be used in new fuel rods) plus the fourth stream of what are actually waste products (called high-level waste).

4. If you follow the link https://britain-watch.co.uk/energy-and-environment/ you can view a paper about nuclear power generation called “Background Briefing Paper on the Nuclear Fuel Cycle” by Hill Path Projects Ltd, which includes sections on recycling and waste. You will find in Table 1, column 3, an estimate of the high level waste at the end of a 60 year 100 GW programme, i.e. about 10 times the nine nuclear power stations we still have operating (of which all but one – Sizewell B – are due to be shut down by 2023).

5. In column 2 of the table you can see the amounts of the various categories of waste which we already have, or will have as a result of power stations we have currently operating and have had operating in the past (Magnox and AGR types).

6. As you can see by comparing columns 2 and 3, the amount of projected high level waste over 60 years using existing PWR technology is only about one sixth (per unit of electricity generated) of that produced by our earlier technologies (the Magnoxes and AGRs). The reason for this huge reduction in the waste to electricity ratio is 40 years of technical advance (like the increase in miles per gallon for cars for example).

7. The 1,500 cubic metres of high-level waste from 60 years of operation in column 3 amounts to a cube of side about 11.5 metres and that is from a projected output (100 GW) which is nearly double that of the whole of the UK electricity productive capacity (50 GW) of all kinds today (oil, gas, coal, hydro, wind and nuclear). This 11.5 metre cube (or its equivalent) in smaller chunks will need to be vitrified and buried deep underground long enough for its radiation to fall to the surrounding granite level, but as with the fuel rod containers, the requirements for sealing it from the biosphere are extremely well understood.

8. Intermediate level wastes are not fuel wastes, but equipment items such as pumps and steel vessels from within the reactors which become irradiated in the same way that X-ray materials used in hospitals do and which also have to be buried. Low level waste, much the largest by volume, comprises things like concrete bases where levels of radiation are extremely low and are in any case monitored daily while in use.

9. Finally, you may be interested to know that Britain, along with France and Japan have operated what are called Fast Breeder Reactors (FBRs). These allow every bit of original uranium 238 to be turned into fuel, which is actually the best way of using up the spent fuel we already have stored from past activities (Table 1, column 2).

10. In a decision of exceptional short-sightedness, even by our politicians’ standards, John Major’s Conservative government ordered our Fast Breeder Reactor at Dounreay in Scotland to be closed down in 1994.