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MTR Project BLACKSTONE

MTR Project BLACKSTONE. Tjark van Staveren, NRG Steven Knol, NRG Matthew Brooking, EDF Energy. September 18, 2013. Contents. Graphite irradiation experiments at NRG Introduction project Blackstone Irradiation results Blackstone Phase II Temperature → sensitivity analysis

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MTR Project BLACKSTONE

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  1. MTR Project BLACKSTONE Tjark van Staveren, NRG Steven Knol, NRG Matthew Brooking, EDF Energy September 18, 2013

  2. Contents • Graphiteirradiationexperiments at NRG • Introduction project Blackstone • IrradiationresultsBlackstonePhase II • Temperature → sensitivity analysis • Oxidationandweightloss • Neutron dose • Development of post-irradiationcharacterisationtechniques

  3. Graphiteirradiationprojects at NRG Pre-irradiation examination Experiment assembly Post-irradiation examination Irradiation

  4. Graphiteirradiationprojects at NRG • Supporting EDF Energy AGR life-time extension • BLACKSTONE: irradiation of graphite samples underoxidisingconditions • ACCENT: irradiation of graphite samples under stress • (V)HTR development • Multiple graphiteirradiationexperimentsat different temperatures

  5. Project BLACKSTONE Aim • Expandinggraphite property database to neutron doses andweightlossbeyondcurrentoperation of reactors • Gainunderstanding of graphite property changes underradiolyticaloxidation

  6. Project BLACKSTONE Weight loss Future AGR operation Project Blackstone data AGR trepanning data Neutron dose

  7. Project Blackstone • Phase I • Graphite samples from Hinkley Point B / HunterstonB • One capsule irradiated under inert conditions • One capsule irradiation under oxidising conditions • PIE successfully completed in 2011 • Phase II • Graphite samples from Hartlepool / Heysham1 • Two capsules irradiated under oxidising conditions • PIE started in 2012

  8. Blackstone Phase II • Two irradiation capsules • Targets: 7.4 and 11.0 dpa • Temperature target 420°C • Both contain oxidising environment (CO2/CO) • Two different oxidation rates • Continuous online monitoring of oxidation by analysing ingoing and outgoing gas composition

  9. After irradiation (1)… • Tomograph GE Phoenix X-Ray Nanotom S • 2.5 µm resolutionfor Ø8 mm graphite samples • Possibility of full sample high resolution imaging • Usage: • Tostudyporosityevolution • To support destructivetesting • To check homogeneity of oxidation 5.7 mm Beam 0M22: 57.5% weight loss

  10. After irradiation (2)… • DIC system installed in hot cellandglovebox in 2013 • High resolution imaging of flexural, compressiveandtensile tests • Next step: determinationstaticYoung’s modulus But first… Beam 3M02: 32% weight loss

  11. Key irradiation challenges • Control of temperature: stable and on target • Control of oxidation and weight loss during irradiation • Neutron dose on target

  12. Drum based design 24 thermocouples per capsule Primary gas flow through and around drums CO2/CO mixture Secondary gas around capsule: stationary He/Ne mixture for temperature control Oxidation is measured by gas chromatography on inlet and outlet of experiment Design principles

  13. Thermomechanical design Principles Heating by neutrons and gamma radiation Temperature determined by many factors heat input (neutron and gamma fluxes) density of parts thermal conductivity of parts gas composition gas flow gas gap sizes Two step temperature determination approach Modeled • Tsample= Tthermocouple + dT Measured

  14. Thermomechanical design Outer gas gap (He/Ne mixture) Thermocouple Quattro tube Thermocouple gas gap (He or CO2 mixture) Containment tube Sample holder (aluminium drum) dT Gas tube Inner gas gap (He or CO2 mixture) Specimen gas gap (He or CO2 mixture) Specimen

  15. Finite element model • Finite element model programmed in ANSYS Specimen Quattro tube Outer gas gap (He/Ne mixture) Containment tube Inner gas gap (He or CO/CO2mixture) Sample holder (aluminium drum) Thermocouple

  16. Temperature sensitivity study • Aim • To assess the sensitivity / dependence of the sample temperature to all relevant parameters • Determine dT using parameter set of choice • A large number of parameters is varied, such as: • Sample properties • Properties of irradiation rig • 8000 runs are performed with different sets of parameters dT Parameter value

  17. Sensitivity study dT Al conductivity dT Sample density

  18. Temperature Assessment • Start and end of irradiation sample temperatures are assessed • Sample parameters data: • Measured data from dimensional, CTE, LFA measurements • Measured conductivity data for most samples, if not, modelled data is used • Heating, adjusted based on Blackstone Phase I experience • Assumption that drum shrinkage occurs early in irradiation

  19. Temperature Assessment • Excellent correlation between modelledand measured thermocouple readings

  20. Temperature Assessment • Based on measured temperature and modeled temperature difference, temperatures at BOI are slightly higher and EOI slightly lower. • Weight loss affects sample temperature

  21. Gas handling system Goal Oxidise and irradiate the specimens simultaneously Control a flow of an oxidising gas mixtures around the specimens Switch to helium during reactor start up and in case of emergency Be able to measure the concentrations of the following components: Water, ethane, methane, CO, hydrogen, neon (reference)

  22. Gas handling system Solution A dedicated gas handling system is built. Gas chromatographs measure concentrations at inlet and outlet of experiments A measurement is made every 15 minutes every day of the irradiation The data is analysed quickly and can be used to tune the oxidation rate Oxidation rate can be adjusted by changing gas composition or gas flow

  23. Weight loss and neutron dose Blackstone 04 weight loss: Target was 18.855 g Based on online GC data: 18.885 g Based on PIE data 19.389 g Blackstone 04 neutron dose: • Target was > 7.4 dpa • Based on online calculations: 7.846 dpa • Based on PIE monitor sets: 7.835 dpa

  24. Summary • Succesfullirradiation of first capsule BlackstonePhase II • Temperatureswithinspecification, more accurate determination of sample temperaturesaftersensitivity analysis • Neutron dosewithinspecification • Excellent weightloss control • Samples recoveredfrom capsule 04 • PIE Campaign ‘capsule 04’ started • Next Phase II ‘capsule 03’ expectedtobedismantled in November 2013

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