The INNOGRAPH-1C low dose irradiation experiment extending the HTR graphite materials properties curves at 750°C Maurits Heijna INGSM September 2014 Hangzhou

15 th INGSM Hangzhou, China European HTR graphite program (V)HTR: (Very) High Temperature Reactor Goal of INNOGRAPH irradiations: Get design curves of modern nuclear graphite grades and select best candidate for (V)HTR Add to understanding of graphite irradiation behaviour

15 th INGSM Hangzhou, China INNOGRAPH irradiation experiments 3

15 th INGSM Hangzhou, China INNOGRAPH irradiation experiments 4 INNOGRAPH-1C: low dose irradiation at 750°C

15 th INGSM Hangzhou, China ManufacturerGradeCokeProcess IG-110petroleumiso-moulding IG-430pitchiso-moulding NBG-10pitchextrusion NBG-17pitchvibro-moulding NBG-18pitchvibro-moulding NBG-25petroleumiso-moulding PCEApetroleumextrusion PCIBpetroleumiso-moulding PPEApitchextrusion LPEBneedleextrusion LPIBneedleiso-moulding Graphite grades in INNOGRAPH 5 Variation in manufacturing process, coke, and grain size

15 th INGSM Hangzhou, China INNOGRAPH experiment design 6 8 drums to hold samples Geometry allows grain orientation identification In the order of samples per experiment Each experiment contains 24 thermocouples and 9 dosimeter sets

15 th INGSM Hangzhou, China INNOGRAPH experiment design INNOGRAPH-1B and -2B have been assembled in the NRG hot-cells Samples include irradiated samples from INNOGRAPH-1A and -2A INNOGRAPH-1C: virgin samples only, table top assembly

15 th INGSM Hangzhou, China INNOGRAPH-1C irradiation 8 3 cycles in high flux position in High Flux Reactor (HFR, 45 MW) Helium gas environment

15 th INGSM Hangzhou, China Irradiation temperature control 9 On-line temperature control by gas mixture control and vertical displacement unit

15 th INGSM Hangzhou, China Post-Irradiation Examination 10 PIE measurements: Dimensional change Mass & density Young’s modulus Thermal conductivity Thermal Expansion Measurement set-ups in Box and Hot Cell Sample recovery Measurements Drum recovery

15 th INGSM Hangzhou, China Volume change (T irr =750°C) 11 ExtrusionIso-moulding

15 th INGSM Hangzhou, China Volume change (T irr =750°C) 12 ExtrusionIso-moulding

15 th INGSM Hangzhou, China Dynamic Young’s Modulus 13 ExtrusionIso-moulding Measured by velocity-of-sound

15 th INGSM Hangzhou, China Dynamic Young’s Modulus 14 ExtrusionIso-moulding Measured by velocity-of-sound

15 th INGSM Hangzhou, China Dynamic Young’s Modulus 15 ExtrusionIso-moulding Measured by velocity-of-sound

15 th INGSM Hangzhou, China Thermal expansion 16 ExtrusionIso-moulding Measurement range used: 30°C-750°C

15 th INGSM Hangzhou, China Thermal expansion 17 ExtrusionIso-moulding Measurement range used: 30°C-750°C

15 th INGSM Hangzhou, China Thermal expansion 18 ExtrusionIso-moulding Measurement range used: 30°C-750°C

15 th INGSM Hangzhou, China Thermal conductivity vs temperature 19 Measured by Laser Flash Analysis (LFA)

15 th INGSM Hangzhou, China Thermal conductivity vs dpa 20 ExtrusionIso-moulding Measured at 750°C

15 th INGSM Hangzhou, China Thermal conductivity vs dpa 21 ExtrusionIso-moulding Measured at 750°C

15 th INGSM Hangzhou, China Thermal conductivity vs dpa 22 ExtrusionIso-moulding Measured at 750°C

15 th INGSM Hangzhou, China Conclusions Materials properties curves at 750°C extended to low dpa for HTR graphite grades Little happens at low dpa –Volume change –Although indicative for behaviour at higher dose A lot happens at low dpa –CTE, DYM, thermal conductivity To be answered: what grade is best for (V)HTR? 23