European experience with Thorium fuels Didier Haas Didier.haas@hotmail.be ++32 491648840 NC2 Nuclear Consulting Company Thorium Conference, CERN

Thorium Conference, CERN Some references T. Lung: EURATOM report 1777 (1997) THOR Energy Thorium Fuel Conference, Paris (2010) IAEA No NF-T-2.4 (2012): The role of Thorium to supplement Fuel Cycles of Future Nuclear Energy Systems GIF position paper on the use of Thorium in the Nuclear Fuel Cycle (2010) SNETP Strategic Research and Innovation Agenda (2013) and SRA Annex on Thorium (2011) Published EURATOM Framework Programmes results and personal communications Thorium Conference, CERN

Thorium Conference, CERN Content European Research on Thorium Thorium in HTRs Thorium oxide fuel behaviour Molten salt reactors fueled with Thorium Conclusion Thorium Conference, CERN

3 main pillars + key cross-cutting issues Sustainable Nuclear Energy Technology Platform Launched in 2007 117members from research, industry, academia, technical safety organizations Recent application of Weinberg Foudation (UK) and ThorEA (UK) both promoting Thorium research Produced a Research Agenda (2009, revised in 2013) and a Deployment Strategy (2010) 3 main pillars + key cross-cutting issues 4

European R&D Roadmap on Thorium SNETP has produced an Annex (2011) on Thorium in the Strategic Research Area. Highlights are: LWRs: evolutionary development favoured, with use of Pu as seed (natural U savings); breeding would need new reactor technology HWRs: high conversion ratio achievable HTR: past German HTR development programme aimed at reaching a breeding cycle with Thorium Fast Reactors: breeding possible but with long doubling times; improved void reactivity coefficient in sodium FR; advantage of ADS subcritical reactor (high neutron energies, Th 232 fission + captures) MSR: breeding might be achieved over a wide range of neutron energies; long-trerm development option Pu-burning: Thorium matrices for the purpose of incinerating Pu in LWRs Challenges for solid fuels: reprocessing, remote fuel fabrication Thorium Conference, CERN

Thorium Projects in Europe 1960-1980: limited experimental work on Thorium use in HTRs (DRAGON, ATR, THTR, Th-U carbide and oxide fuels) and in the Lingen BWR by SIEMENS (Th-MOX) 1990-2002: Assessment studies including the « Lung report » and the EURATOM projects « Thorium Cycle as a nuclear waste management option » and « Red Impact » 1998-2008: Thorium fuel experiments (Projects THORIUM CYCLE, OMICO, LWR-DEPUTY with irradiations in KWO-Obrigheim, HFR and BR2) FP7 (2011-13): Performance assessment of Thorium in geological disposal (SKIN Project) FP5-FP7 (1998-now): Thorium fuel studies and characterization for a Molten Salt Reactor (Projects MOST, ALISIA, EVOL…) Thorium Conference, CERN

Thorium use in High Temperature Reactors HTR thermal neutron spectrum is very well suited for Thorium breeding Very high burnup capability in HTRs in a once-through cycle; very high stability in geological disposal of the Thorium matrix This explains the (successful) use of Thorium in early HTR projects (DRAGON, AVR Jülich, Peach Bottom, Fort St-Vrain, THTR); fresh fuel kernels were mixed with Pu or U235 fissile material Potential limitations are the high initial U235 content needed in the once-through strategy and the reprocessing difficulty in case of closed cycle strategy Today, (V)HTR is one of the six GIF R&D systems; European interest in HTR exists, but difficulty in getting industry commitments Thorium Conference, CERN

Thorium fuels in HTRs:Abstract from the « Lung » report Thorium Conference, CERN

Thorium Oxide as a «Quasi »-Inert Matrix ThO2 is a very stable ceramic: in-core applications, direct disposal waste management (see leaching tests results from JRC-ITU Karlsruhe) Th-MOX (Th,PuO2) has been contemplated to incinerate separated Pu in LWRs in a fertile matrix, and also as possible « quasi »-inert matrix for MA burning in « targets » The Th matrix produce no new Pu and is fertile as required to keep the reactivity in LWRs In-reactor properties are equivalent (even better if one considers the thermal behaviour and the stability) to U-MOX Thermal diffusivity measurements on unirradiated Th-MOX at JRC-ITU: higher than U-MOX Thorium Conference, CERN

FP5: THORIUM Cycle for P&T and ADS FP5 ADOPT Coordination Network EUROTRANS FP6 Project FP5 (1998-2002) Projects on Advanced Options for Partitioning and Transmutation

FP6 EUROTRANS Project and THORIUM as P&T fuel Associated Project on Advanced P&T Fuels: LWR-DEPUTY Project with Thorium fuels Inert Matrices fuels Thorium Conference, CERN

(Th,Pu)O2 in-reactor experience (2000-2012) Experiments (Th,Pu)O2 fuels were irradiated in three reactors HFR-Petten (Na-capsule) KWO Obrigheim (non-instrumented, commercial PWR) BR-2 Mol (instrumented & non-instrumented in PWR loop) Post-irradiation examinations & radiochemistry by different labs (ITU, NRG, PSI, SCK•CEN)

Thorium Conference, CERN Th-MOX pellet irradiated in Obrigheim within the FP5 THORIUM CYCLE and LWR-DEPUTY projects Safety assessment of Plutonium Mixed Oxide Fuel irradiated up to 37.7 GWd/tonne (JNM 2013) J. Somers1,*, D. Papaioannou1, J. McGinley1, D. Sommer2 1. Joint Research Centre – Institute for Transuranium Elements, Postfach 2340, D76125 Karlsruhe, Germany 2. EnBW Kernkraft GmbH*, Postfach 1161, 74843 Obrigheim and Böhmerwaldstraße 15, 74821 Mosbach, Germany Thorium Conference, CERN

Thorium Conference, CERN Thermal Behaviour From: C. Cozzo et al., J. Nucl. Mater. (2011), doi:10.10C. Cozzo et al., J. Nucl. Mater. (2011), Thorium Conference, CERN

Th-MOX Thermal Conductivity as compared to U-MOX C. Cozzo et al., J. Nucl. Mater. (2011), doi:10.10C. Cozzo et al., J. Nucl. Mater. (2011), At 1000K TC of U-MOX: 3.0-3.5 of Th-MOX: >4.0 !! Importance of the fabrication process D. Staicu, M. Barker, J. Nucl. Mater. (2013), http://dx.doi.org/10.1016/j.jnucmat.2013.08.024 Thorium Conference, CERN

BR-2 experiments on (Th,Pu)O2: Model predictions versus experiment 5 cycli in 2006 Copernic = AREVA code; Transuranus = ITU code Personal communication By courtesy of SCK-CEN

Leaching test on Th-MOX Source: Rondinella & Al (JRC-ITU) Paris Thorium technical meeting 2010 Thorium Conference, CERN

Thorium Conference, CERN SKIN Euratom Project (2011-2013) Comparison of solubility values of elements of interest Reference case: SKB spent fuel repository Bx, Gx: compartments of Bentonite, Granite Thorium Conference, CERN

SCK-CEN (BE) key findings from the Euratom (Th, Pu)O2 research programs No showstoppers identified for Thorium-based MOX (Th,Pu)O2 to its implementation as a possible LWR-fuel. (Th,Pu)O2 has several advantages over Uranium-based MOX (U,Pu)O2 Better thermal conductivity (unirradiated data only) Improved chemical stability Indications for improved reactivity margins for full-core PWR (Th,Pu)O2 compared to (U,Pu)O2 Next steps: Improving the fuel manufacturing technology, since the scoping studies used non-industrial (& non-industrialisable) manufacturing routes; tests on representative fabrications needed Larger-scale demonstration programs with lead-rod and lead-assembly irradiations are needed before licensing Personal communication By courtesy of SCK-CEN

Use of Thorium in Molten Fuel Reactors In MSRs thorium cycle can achieve a higher conversion ratio than the uranium/plutonium cycle. MSR avoids some of the loss of conversion efficiency that occurs due to neutron capture events in Pa-233 (Pa-233 has a relatively long half-life of 27 days). The nuclear fuel in MSR is unique in that it circulates through the entire primary circuit and spends only a fraction of its time in the active core. This reduces the time-averaged neutron flux that the Pa-233 sees and significantly reduces the proportion of Pa-233 atoms that are lost to neutron captures MSR continually reprocesses the nuclear fuel as it re-circulates in the primary circuit, removing fission products as they are generated. MSR therefore completely avoids the difficulties in conventional reactors with fabricating U-233 fuels (which have high gamma activities from U-232 daughters). Since the nuclear fuel is a molten salt, there are no fuel mechanical performance issues to consider. Thorium Conference, CERN

MSR R&D in Europe and elsewhere From MOST to EVOL A continuous and coordinated activity (European network) since 2001 2001-2003 Confirmation of MSR potential Identification of key issues (vs MSBR) MOST from MSBR 6 countries + Euratom 2004-2006 Strenghthening of European network Follow-up of R&D progress LICORN 7 countries + Euratom + Russia ALISIA 2007-2008 Review of liquid salts for various applications Preparation of European MSR roadmap 7 countries + Euratom + Russia SUMO  2009 Feasibility demonstration of MSFR 8 countries + Euratom + Russia EVOL 2009-2012 Optimization of MSFR (remaining weakpoints) 7 countries + Euratom (+ Russia) … to MSFR Thorium Conference, CERN

Thorium Conference, CERN Strategic impact of EVOL A common European Molten Salt Reactor concept for GENIV (major European contribution to the MSR GENIV initiative) Thorium as a nuclear fuel (closed MSR fuel cycle, sustainable energy system) Partitioning & Transmutation (alternative route for P&T compared to solid fuel) Improved understanding of liquid salt properties (MSR technology, but also other industrial processes) Thorium Conference, CERN

MSFR concept MSFR reactor concept (French concept) (Molten Salt Fast Reactor) Initial MSFR fuel composition: X(LiF) = 77.45 mol% X(ThF4) = 20 mol% (LiF-ThF4 eutectic) X(UF4) = 2.55 mol% Operating temperature: Tinlet = 620 °C MSFR pre-conceptual design, GIF Annual Report 2009: (MSR)

Thorium Conference, CERN JRC ITU Molten Salts Database Molten Salt Database developed at JRC (ITU) (2002-2010): 38 assessed binary systems Thorium Conference, CERN

Thorium Conference, CERN Conclusion Several EC Projects on Th-MOX fuels mainly for LWRs as « Quasi »-Inert matrix to burn Pu and MAs Thorium salts as fuel for the MSR The SRIA published in 2013 recognises the « significant long-term potentialities and the significant challenges to make industrial implementation » of Thorium systems Thorium Conference, CERN

Thank you for your attention ! With particular thank to Michel Hugon and Roger Garbil (EC DG RTD, Brussels), Vincenzo Rondinella, Dragos Staicu, Joe Somers (EC JRC, ITU, Karlsruhe) and Marc Verwerft (SCK-CEN) for their assistance in providing all relevant information and comments. Thorium Conference, CERN