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Safety of Innovative Reactors Designs


Specific Objectives:
1. To test the integrity and fission gas release of HTR fuel compacts provided by General Atomics;
2. To test the integrity and fission gas release of HTR fuel pebbles provided by FZJ during irradiation in the HFR; to irradiate these pebbles to a high burn-up (for enabling subsequent accidental fission gas release tests in the KÜFA facility at JRC-ITU); to allow for simultaneous piggy-back testing of graphite specimens;
3.1. To design, build, commission and test a new facility to carburise and decarburise test coupons; 3.2. To modify an existing facility for measuring the impact, tensile, creep, and fracture mechanics properties of: - surface-treated Ni superalloys (and possibly Ti or Mo base alloys or CFC or SiC/SiC composites) for HTR He turbines - HTR reactor pressure vessel material including thick welds on commercial P91 steel - carbon fiber composites (CFC) for HTR control rod clads;
4. To pursue with HTR-TN partners the coordinated definition and execution of R&D;
5. To review existing HFR fuel test reports and to develop a user- friendly interface for facilitating data entry in the fuel database;
6. To contribute to the final definition of selection criteria for innovative reactors and fuel cycles in IAEA/INPRO;
7. To modify certain computer codes (EAC2, STAR-CD) to make them suitable for use with the coolants lead and helium. To prepare reactivity worth curves with the neutronic code HEXNODYN. Accident initiators that will be investigated are unprotected Loss-of-Flow, Loss-of-Heat Sink, depressurisation- and reactivity-accidents as well as emergency decay heat removal; 8. To perform a feasibility study for a small-scale out-of-pile experiment to verify whether Pb or Pb-Bi will absorb Cs and I vapours. Anticipated milestones and schedule M1.1 HFR-EU2 fabrication finished: 09/2003 M1.2 HFR-EU2 start of irradiation: 12/2003 M2.1 HFR-EU1bis fabrication finished: 06/2003 M2.2 HFR-EU1bis start of irradiation: 07/2003 M3.1 Fracture mechanics facility operational: 09/2003 M3.2 Facility to pre-expose samples in carburising or de-carburising atmospheres operational: 09/2003 M5.1 User interface with HTR fuel database installed: 09/2003
Planned Deliverables:
1. HFR-EU2 irradiation: Design and follow-up of fabrication of rig and loops. Start of irradiation. Reports 2. HFR-EU1bis irradiation: Design and follow-up of fabrication of rig and loops. Start of irradiation. Reports 3. Commissioning of the surface treatment facility and of the mechanical test rig. Report 4. Participation in project review meetings, preparation of FP6 project contributions. Minutes Co-organise International Conference on Advanced Power Plants 2003 (ICAPP'03) Co-organise Conference on High Temperature Reactors (HTR-2004) 5. Installation of user-friendly interface for data entry in HTR fuel database at JRC-IE. CD with software and manual 6. Contribution to TECDOC on IAEA/INPRO. Report 7. Safety analysis of lead-cooled fast reactors. Report Modified thermal-hydraulics model in the EAC-2 multi-channel accident code for gas cooling. CD with software 8. Feasibility study of an out-of-pile experiment with Pb, Pb-Bi and I and Cs.
Summary of the Action:
In 2003, the JRC-IE actions on HTRs cover: out-of-pile tests and irradiation of HTR fuel and of structural materials in the High Flux Reactor (HFR) The irradiation work covers the complete range of: Preparatory work (feasibility studies, specifications, planning, detailed design and analysis, fabrication, assembly, commissioning, and deployment of the rig and ancillary equipment, pre-irradiation metrology, cold tests, operator training etc.) Irradiation in the HFR of structural materials and of fuel with on-line fission gas release measurement and possibly corrective actions (temperature and flux adjustments) on a daily basis Cooperation with the HTR-Technology Network Definition of a user interface for the fuel data base structure In 2003, the following actions will contribute to the safety of future reactor concepts: Reactor safety analysis on Generation IV concepts (LFR and GFR) Definition of reactor concept selection criteria for IAEA/INPRO Feasibility study of out-of-pile experiment to determine whether Pb and Pb- Bi coolants absorb caesium and iodine vapours Rationale This JRC-IE action supports R&D efforts related to future nuclear power plants for the medium and the long term. The tasks are thematically inter-related and focus on the safety analysis and safety optimisation of reactors, fuels and materials with improved sustainability and waste management features. High Temperature Reactors feature numerous advantages both as replacements of third-generation Light Water Reactors or Gas Cooled Reactors, and as new installations.

HTRs (as "Generation III+" concepts, available by 2015) also prepare options for further improved sustainability and waste management. They also offer synergies that could lead to thermal or fast gas- cooled "Generation IV" concepts (available by 2030). Several countries have launched significant R&D efforts on different HTR concepts. JRC-IE contributes technically to this R&D with out-of-pile structural material tests and with the preparation, the execution and the scientific analysis of irradiation experiments on HTR fuel and on structural materials in the HFR Petten. This work focuses on safety-relevant aspects of HTRs such as the integrity of fuel and of structural materials with increasing neutron fluence at typical HTR operating conditions. JRC-IE will continue its cooperation with the HTR-Technology Network to maintain tight links with other European key players and to ensure that its R&D input is in line with the requirements of technical, scientific and industrial projects. Additionally, JRC-IE contributes to the establishment of an HTR fuel database to recover a maximum of knowledge from mothballed reports in various European institutions and companies. Future Reactor Concepts: Euratom intends to sign the Generation IV International Forum (GIF) chart and will contribute to the related R&D program on future reactor concepts. At the same time, the IAEA (with mainly non-OECD participants) pursues another project for identifying future reactor concepts and fuel cycles. GIF has already selected 6 reactor concepts for long-term development: sodium- and lead-cooled fast reactors, gas-cooled fast reactor (GFR), supercritical water reactors (SCWR), molten salt reactors (MSR), and very high temperature reactors (VHTR).

A first prototype of a lead/lead-bismuth cooled fast reactor may be built in Russia in the medium term. GFRs receive strong emphasis in three large nuclear countries (France, UK, US). In response to these initiatives, the JRC-IE contribution consists in 2003 of a detailed analysis of severe accident aspects of LFRs and GFRs, with the aim of addressing feasibility issues and identification of possible system improvements.


Institute for Energy
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