Synergy between Fast Reactors and Thermal Breeders for Sustainable Nuclear Power Kamil Tuček

1. Synergy between Fast Reactors and Thermal Breeders for Sustainable Nuclear Power Kamil Tuček http://ie.jrc.ec.europa.eu

2. Outline Requirements for Next Generation Reactor Systems Fertile Material Demand and Supply 233U Breeding in Thermal and Actinide Waste Burning in Fast Reactors to Achieve Rapid Increase of Nuclear Capacities Prospects and Technological Challenges

3. Projected Nuclear Energy Capacity Increase Scenario of Energy Growth for a Sustainable Future. Energy to 2050: Scenarios for a Sustainable Future. IEA and OECD, Paris, France (2003) The share of nuclear power is forecast to increase considerably by 2050, with a median of more than four times. However, a much larger growth of nuclear power would be needed (10-15 times the current capacity), if emissions of green house gases are to be stabilized and then decreased beyond 2050-2060.

4. Requirements for New Reactor Systems • Sustainability •  waste management •  efficient utilization of fuel (breeding) • safety (inherent and passive) Economical competiveness • comparable with PWRs Acceptable proliferation characteristics European Lead-cooled System (ELSY)

5. Sustainability of GEN-IV Systems Closing of Fuel Cycle for TRUs TRU (Pu+MA)recycling/burningradiotoxicity and heat load reduction

6. Sustainability of GEN-IV Systems LWR and FR Waste Burning Are you in favour or opposed to energy produced by nuclear power stations? (%EU) If the issue of nuclear waste was solved, would you be then in favour or opposed to energy produced by nuclear power stations? (%EU) Special EUROBAROMETER on Radioactive Waste, 2005

7. Uranium Demand and Supply “2005 Red Book” by OECD/NEA and IAEA Known + undiscovered conventional 14.8 million tonnes Unconventional (in phosphate deposits) 22 million tonnes Current consumption = 68 000 tonnes/year for 360 GWe NPP park (only 40 000 tonnes/yr mined) Without breeding, this is enough to sustain nuclear energy production for more than 250 years at current consumption levels PWRs use only 0.8-1.0% of the potential energy of mined uranium. In U-Pu cycle, to sustain the increase in nuclear capacity by more than a factor four, fast breeder reactors with large breeding ratios need to be introduced by 2040. Doubling times to start these additional FRs are still too long (15-30 years). IAEA/INPRO 8th Steering Committee Meeting, 2005

8. Thorium World Thorium Reserves (economically extractable) • high fuel conversion/self-breeding in thermal neutron spectrum possible: CANDU or Indian Advanced Heavy Water Reactor (AHWR) are shown to be self-sustained in 233U! • very little long-lived radiotoxic actinides (Pu + minor actinides – Am, Cm) is produced • Th abundance in Earth’s crust 3 times larger than that of uranium (9.6 ppm vs. 2.5-3 ppm) • converting all 1.2 million tonnes of economically extractable Th reserves to 233U and its fissioning would give energy for ~3000 yearsat current generation levels US Geological Survey, Mineral Commodity Summaries, 2005

9. Fuel Cycle Layout Fast 233U Breeder/ MA Burner Reactors (FR) – Gen IV: Sodium-cooled FR Lead-cooled FR Gas-cooled FR Thermal Converters / Breeders: Gen II/III: Pressurized Heavy Water Reactors (PHWRs): CANDU, AHWR Gen IV: Molten Salt Reactors (continuous removal of 233Pa possible) 232Th + n → 233Th → 233Pa → 233U b– (22 min) b– (27 days)

10. Generated 233U and Burned MAs in a FR 600 MWe Lead-cooled Fast Reactor Fast reactor simultaneously: • burns its own MA waste + those generated in PWRs • breeds enough 233U to start a new 850 MWe CANDU reactor (having a 233U fissile inventory of 1.6 tonnes) in 7.5 years (compare with FR doubling time of 15–30 years) To achieve even faster doubling times (4 years), FR should employ only Pu-based fuels.

11. 233U, 232U Production in a PWR vs. FR Pressurized water reactor: • breeds enough 233U to start a new 850 MWe CANDU reactor in 12 years Proliferation resistance due to predetonations caused by (a,n) reactions as a result of 232U decay (half-life 69 years) if 232U fraction in uranium vector exceeds 1000 ppm • achieved in less than 1 yr in PWRs having ThO2 pins places in each fuel sub-assembly • to reach ~1000 ppm of 232U in fast reactor, fuel needs to stay in the core at least 5 years

12. Synergy between FRs and Thermal Breeders:Prospects • Fast increase of nuclear power capacities possible. In 50 years, 233U produced in 300 PWRs could be used to start-up up to 1200 thermal breeders (850 MWe PHWRs) with a total installed capacity of more than 1000 GWe one FR can be used to start-up six 850 MWe PHWRs (total capacity 5950 MWe); in U-Pu cycle FR could produce 2-3 Pu critical masses (total capacity 1800-2400 MWe) 300 FRs could be used to start-up 1800 PHWRs, giving a total installed capacity of 1500 GWe • Significant reduction of long-term radiotoxic inventory of spent fuel and nuclear waste • Higher fertile material utilization. Even for start-up scenarios not considering reprocessing, once-through Th-U fuel can reach 4 times higher burn-up (up to 30 GWd/tHM) in a PHWR breeder than is typical in CANDUs using natural uranium fuel Use of Th additionally brings: • Improved reactor safety margins due to 500 K higher melting point of ThO2 in comparison to UO2

13. Synergy between FRs and Thermal Breeders: Technological Challenges and Barriers • Remote handling will be needed to fabricate 233U bearing fuels and during operations including reloading of fuel back to the reactor due to high specific activity of 232U daughter products (208Tl, 2.6 MeV g’s). This will also make this strategy little more expensive than U-Pu cycle is. Technology transfer from remote fabrication techniques developed for MOX fuels possible. • Reprocessing technologies need to be developed and achieve industrial viability Aqueous reprocessing: Thorium-uranium extraction (THOREX) technology under further development in India (poor solubility of Th-based fuels in HNO3 necessitates use of HF, which causes corrosion problems; Pa not recoverable) Pyroreprocessing: Molten salt/liquid metal extraction (Pa recoverable)

14. Outlook & Conclusions • Short-term application of Th-U cycle in PHWRs is attractive if fast increase of nuclear capacities is demanded and/or if development of fast reactors encounters unexpected technological or societal problems • In medium and long-term perspective, Th holds a promise of enhancing energy potential of fertile material, conservatively by at least a factor of two (depending on amount of Th resources discovered)

15. Reactivity Swing in Th-U Breeder/Burner LFRs

16. Advanced Heavy Water Reactor (AHWR)

17. Generated Pu and Burned MAs in a FR In optimized MA incinerators (MAs in the core and in the blankets) about 120 kg of MAs can be transmuted per year. This corresponds to an annual production of minor actinides in 2.5 EPRs.