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Transmutation Mission

Transmutation Mission. Workshop on Applications of High Intensity Proton Accelerators October 19-21, 2009 Fermi National Accelerator Laboratory, Batavia, IL, USA Won Sik Yang Argonne National Laboratory. Background.

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Transmutation Mission

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  1. Transmutation Mission Workshop on Applications of High Intensity Proton AcceleratorsOctober 19-21, 2009Fermi National Accelerator Laboratory, Batavia, IL, USA Won Sik Yang Argonne National Laboratory

  2. Background • Nuclear energy is a significant contributor to U.S. and international electricity production • 16% world, 20% U.S., 78% France • Given the concern over carbon gas emissions, there may be significant growth worldwide • In the U.S., a once-through fuel cycle has been employed to-date • Large quantities of spent fuel stored at reactor sites • Final waste disposal is not secured • With nuclear expansion, this is not a sustainable approach; thus, advanced fuel cycles being explored – two key goals • Waste management • Resource utilization Argonne National Laboratory

  3. Objectives of Advanced Fuel Cycle • Reduce the long-term environment burden of nuclear energy through more efficient disposal of waste materials • Remove transuranics (TRU) from waste • More efficient utilization of permanent disposal space • Significantly reduce released dose and radiotoxicity • Enhance overall nuclear fuel cycle proliferation resistance via improved technologies for spent fuel management • Avoid disposal of weapons usable materials • Improve inherent barriers and safeguards • Enhance energy security by extracting energy recoverable in spent fuel, avoiding uranium resource limitations • Extend nuclear fuel supply • Continue competitive fuel cycle economics and excellent safety performance of the entire nuclear fuel cycle system Argonne National Laboratory

  4. Transmutation System Approach Argonne National Laboratory

  5. Waste Management Objective: Radiotoxicity Reduction • Continuous recycle required for significant reduction of radiotoxicity • Continuous recycle strategy can significantly improve the basic nature of nuclear waste disposal (thermal load and isolation time frame) Argonne National Laboratory

  6. Spectral Effect on Transmutation Physics • Fissile isotopes are likely to fission in both thermal/fast spectrum • Fission fraction is higher in fast spectrum • Significant (up to 50%) fission of fertile isotopes in fast spectrum • More excess neutrons and less higher actinide generation in fast system Argonne National Laboratory

  7. Fast Reactor Transmutation Analyses Fast reactors with closed fuel cycle can effectively manage TRU by varying the TRU conversion ratio (production/destruction rate) • Can be configured as modest breeders (CR≥1) to moderate burners (CR≥0.5) with conventional technology • Low conversion ratio designs (CR<0.5) have been investigated for transmutation applications • High enrichment fuels are required (~50% TRU/HM for CR=0.25) • Non-uranium fuel would be needed to achieve CR=0 • If two design objectives of maximizing the TRU consumption rate and minimizing the reprocessing loss of TRU to the geological repository are pursued, a compromised TRU conversion ratio would be in the range of 0.2 to 0.4 • Safety performance will change at low uranium content (e.g., reactivity losses, and reduced Doppler and Beta, and increased sodium void worth) • Detailed safety analysis conducted for CR range • Passive safety behavior of metallic-fuel FR is not compromised Argonne National Laboratory

  8. Normalized TRU Charge and Consumption Rates • TRU consumption rate (relative to the maximum theoretical value of uranium-free fuel) reaches ~80% of the maximum theoretical value when TRU CR is in the range of 0.25-0.35 • TRU charge rate (relative to the breakeven core) increases with decreasing TRU CR Argonne National Laboratory

  9. Comparison of Fast Reactor (FR) and Accelerator Driven System (ADS) • Either system transmutes transuranics in a fast spectrum • Electricity generation costs of ADS higher than for FR approaches • Differences of 10-25% depending on level of first tier burning • Fast reactors ideal as a single-tier system • Significant electricity generation and transuranics (TRU) consumption • ADS best suited to second tier of a double-tier system • Target deep burnup in the first tier, preferably using commercial reactors, to limit number of second tier systems • Different level of maturity and technical risk • FRs closer to deployment • Fuel cycle R&D required for all scenarios • Future nuclear energy scenario will be a key consideration • Growth – favors FR with moderate support ratio • Contraction – ADS system (using non-uranium fuel) destroys material more quickly Argonne National Laboratory

  10. Cost of Electricity (mill/kWeh) Relative cost (%) “ADS and FR in Advanced Nuclear Fuel Cycle – A Comparative Study,” NEA3109 (2002) Comparison of Cost of Electricity (COE) for Transmutation Scenarios • Fast spectrum system used for consumption of minor actinides and reminant Pu • 0, 1, 2 and C designate zero-, one-, two and continuous-recycle of Pu in intermediate tier Argonne National Laboratory

  11. Typical TRU Content and Support Ratio • An example: a regional (European) scenario with ADS • Group A is in a stagnant or phase-out scenario for nuclear energy and has to manage the plutonium and minor actinides (MA) of spent fuel • Group B is in a continuation scenario for the nuclear energy and has to optimize the use of plutonium resources for the future deployment of fast reactors.The deployment of Fast reactors is delayed and there is need to manage MA inventory increase • The main objective of this scenario is to decrease the stock of spent fuel of countries of Group A down to ~0 at the end of the century, and to stabilize both Pu and MA inventories of Group B • In order to stabilize the MAs production from Group B, the required number of ADS  (~400 MWth) was determined to be 27 units Argonne National Laboratory

  12. Concluding Remarks • Either FR or ADS system can be used for TRU transmutation mission • Purpose of transmutation strategy/system needs to be clarified • Nuclear growth or end; material stabilization or burn-down, etc • Dynamic scenario studies need to be performed to quantify deployment approaches and impacts to nuclear park • Instantaneous support ratios of scenarios calculated by dynamic and equilibrium simulations differ (time lag impacts) • Non-uranium or minor actinide only fuel is attractive for dedicated transmutation systems but would need a significant development time • Reactivity losses must be compensated in sub-critical system (variable source strength, etc) • Approach might be different from that used for fast reactor • Material performance degradation in ADS due to high energy proton and neutron irradiation needs to be considered • Innovative design solution may be required to provide inherent beam control and/or shutdown • Subcritical operating state greatly reduces the effectiveness of inherent passive safety reactivity feedbacks Argonne National Laboratory

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