MTR Project ACCENT T.O. van Staveren, NRG A.J. de Koning, NRG M. Davies, Frazer Nash Consultancy September 18, 2013

MTR Project ACCENT Goal Status of project Design Samples Irradiation PreIE and PIE program 2

MTR Project ACCENT MTR: Materials Test Reactor ACCENT: AGR Carbon Creep experimENT Goal: Provide irradiation creep data on (radiolytically oxidised) graphite –Input to models that predict graphite property changes for EDF Energy Advanced Gas-cooled Reactors 3

Plan Irradiate graphite samples at high temperature under stress in the High Flux Reactor in Petten Perform multiple irradiation and post-irradiation characterisation stages to determine graphite properties at different dpa values Load virgin and radiolytically oxidised samples to determine irradiation creep behaviour at low / high neutron dose and weight loss 4

Project status 5 Conceptual design Detailed design Sample machiningPre-characterisation Assembly and commissioning Phase I Irradiation: 1 cycle with ~0.7 dpa increment Phase I Post-irradiation characterisation Assembly and commissioning Phase II Irradiation: 6 cycles with ~4 dpa increment

Project status 6 Program on schedule: Start of design phase: mid-2012 Machining of radiolytically oxidised specimens: February 2013 PreIE: Spring 2013 Module assembly: June 2013 Phase I Irradiation: July 2013 PIE: August / September 2013 Assembly Phase II: October 2013 Phase II irradiation: November 2013

Design 7 Samples loaded in 6 modules Instrumented holder for modules with 24 thermocouples Sample target temperature: 420°C 10 MPa on stressed samples applied by gas filled bellows Samples under inert atmosphere

8 Instrumented holder with 24 thermocouples → online temperature monitoring Temperature controlled by He/Ne gas mixture in 2nd containment SiC temperature monitors → post mortem temperature analysis of samples and bellows Temperature control

Bellow system 9 4 samples per module 2 samples under stress Helium gas filled bellows 10 MPa reached when experiment is at temperature –Irradiation temperature at bellows determines load on samples Filler and pressure parts for articulation and heat isolation Bellow Pressure part Sample

Samples 24 samples in 6 modules –Two paired samples per module –One sample in a pair is loaded to 10 MPa Target samples give ‘3 Experiments’ –Virgin Gilso graphite → ‘Experiment 2’ –Radiolytically oxidised graphite at intermediate neutron dose and weight loss (ex-Blackstone) → ‘Experiment 3’ –Radiolytically oxidised graphite at high neutron dose and weight loss (ex-AGR, ex-Blackstone) → ‘Experiment 1’ 10

Samples at start of Phase I 11 dpa Dimensional change (%) 2 Experiment 2: virgin graphite 3 Experiment 3: radiolytically oxidised graphite, ex-Blackstone 1 Experiment 1: radiolytically oxidised graphite, ex-AGR and ex-Blackstone

Sample geometries 12 Experiment 1 Sample machined from flexure tested beams, ex-AGR, ex-Blackstone 6 x 6 x 5.5 mm Max. weight loss 37% Experiment 2 Virgin samples 12.5 x 6 x 5.5 mm Laser engraving on one side Experiment 3 Samples machined from cylinders irradiated in Blackstone Phase I 11.8 x 6 x 5.5 mm Max. weight loss 8%

Sample machining (EXP 1) Samples radiolytically oxidised in AGR and High Flux Reactor Petten Blackstone irradiation Flexural tested beams, fracture surface ground back to give specimen pairs Marking of specimen needed to guarantee maintaining orientation relationship: grinding of corner 13

Pre-characterisation 14 Pre-stress testing Photography Dimensions Mass CTE (3 directions) DYM (3 directions) Electrical resistivity ‘Standard’ XRD XRD texture Tomography 10 MPa Loading samples to 10 MPa DIC data recording Photography Dimensions Mass CTE (3 directions) DYM (3 directions) Electrical resistivity ‘Standard’ XRD XRD texture Tomography Before pre-stress testing After pre-stress testing

Assembly Module parts and radioactive samples assembled in glove box Bellows pressurised with helium Orbital welding of modules Leak tightness testing 15

Phase I irradiation Irradiation from 13 July to 6 August 2013 dpa target reached: 0.7 dpa Stable temperatures throughout irradiation Analysis SiC temperature monitor ongoing –Anneal SiC monitors at increasing temperatures –Measure electrical resistivity of SiC after each annealing step 16

Dismantling Modules punctured to check for leaking of modules and bellows during irradiation Modules opened with milling machine in hot cell Samples successfully retrieved from modules in hot cell 17

PIE Started beginning of August End: last week Measurements: –Photography –Dimensions –Mass –CTE –DYM –Electrical resistivity –‘Standard’ XRD –XRD texture –Tomography Results… 18

Next steps Continue assessment of Phase I irradiation –Analysis of SiC temperature monitor sets –Analysis of neutron dosimetry sets Report post-irradiation characterisation measurements Assemble ACCENT Phase II irradiation experiment Start Phase II irradiation 19

Conclusions Successfull machining and pre-characterisation of radiolytically oxidised graphite samples Phase I irradiation completed: dpa target reached Stable temperatures throughout irradiation Confirmation of irradiation temperature on-going Successfull completion of PIE measurements Project on schedule for Phase II irradiation 20