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FNR TRU Issues

By Charles Rhodes, P.Eng., Ph.D.

The embedded cost of energy is a significant cost component of almost everything.

No energy sources are truly sustainable. However, if managed properly, nuclear energy could power planet Earth for several thousand years. If not managed properly, planet Earth will be without sufficient energy before the end of this century.

Today energy production by combustion of fossil fuels moves carbon from the ground to Earth's atmosphere-ocean where it accumulates as CO2 causing global warming. This method of energy production must be halted to prevent CO2 triggered thermal extinction.

Our children's problem with energy production using water cooled nuclear reactors is that these reactors are fueled by the rare uranium isotope U-235, the economic supply of which is limited. During the last 3 years (2021-2024) the price of natural uranium containing 0.7% U-235 has quadrupled. The economic world natural uranium resource will likely be completely depleted by 2070.

Our grand children's problem with energy production using Fast Neutron Reactors (FNRs) will be the shortage and hence cost of TRU. TRU are man made atoms with atomic numbers greater than 92 that enable fission of abundant U-238 atoms in Fast Neutron Reactors (FNRs). By the end of this century the cost of energy will likely be dominated by the cost of TRU.

The TRU shortage is mainly a result of lack of long term power planning. If our grand children are to survive it is essential for us to make as much TRU as possible during the next 50 years. TRU must be preserved, not consumed.

The three practical means of TRU production are: CANDU reactors, Intense Neutron Generators (INGs) with sub-critical U-238 targets, and breeding FNRs. The FNR capacity should gradually grow to fully utilize all available TRU.

1. Today world combustion of fossil fuels liberates an average thermal power of about 20,000 GWt.
2. 100% displacement of fossil fuels with clean energy requires about 20,000 GWt of clean power.
3. Assume that this power must be transmitted via electricity.
4. In a stable and economic clean electricity grid at most 25% of the annual grid energy can come from intermittent renewable generation.
5. Hence in most clean electricity grids 75% of the energy must be nuclear sourced.
6. Present Nuclear Power Plants (NPPs) almost all use thermal neutron (water cooled) reactors. These NPPs use the rare uranium isotope U-235 as fuel.
7. The economic U-235 resource will be depleted by about 2070.
8. For fuel sustainability new nuclear power reactors must be Fast Neutron Reactors (FNRs) which are fueled by the abundant uranium isotope U-238;
9. U-238 is about 140X more abundant than U-235.
10. In a FNR TRU is fissioned while simultaneously U-238 converts to more TRU.
11. TRU can be extracted from used CANDU fuel, can be made using an Intense Neutron Generator (ING) or can be bred in a FNR.
12. There is not enough TRU in used CANDU fuel to deploy the required fleet of FNRs.
13. A CANDU reactor produces 4 g TRU per kg natural U.
14. A CANDU reactor produces 1000 MWe-years per 100 tonnes natural U.
15. Each 300 MWe FNR requires 20 tonnes of TRU to start.
16. An ING with a sub critical target produces 50 TRU atoms per 1 GeV incident proton. A ING with a gross 1 GWt thermal output produces 0.64 tonne TRU / year and generates 333.33 MWe of electricity of which 181.67 MWe feed the ING apparatus and 151.66 MWe are exported.
17. In order to form sufficient TRU to meet the 2070 electricity load today we must make a large investment in CANDU reactors, FNRs and INGs.

This web page last updated February 22, 2024

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