overview on the eu r&d for ceramic breeder materials for ... · 14th workshop on cbbi, sept....

14th Workshop on CBBI, Sept. 6-8, 2006, Petten, The Netherlands

Overview on the EU R&D for ceramic breeder materials for HCPB - TBM

G. Dell’Orco, R. Lässer, Y. Poitevin, M. Zmitko

EFDA CSU Garching

G. Dell’Orco , 14th Workshop on CBBI, Sept. 6-8, 2006, Petten, The Netherlands 2

Presentation outlineEU - TBMs to be tested in ITER Tritium control for TBMs R&D activities on ceramic breeder materials for TBMs

Ceramic breeder materialsMaterial optionsFunctional requirementsSelection criteria

Out-of-pile testing In-of-pile testing Thermo-mechanical modelling

Conclusions


EU - TBMs to be tested in ITER


EU - TBM main aimsEU will test in ITER two TBMs DEMO-relevant blanket concepts with the following main objectives:

• to demonstrate the thermo-mechanical performance of blanket systems under different reactor loading conditions;

• to demonstrate the feasibility of Tritium breeding from Li materials and its recovery and control systems;

• to demonstrate the feasibility of blanket designs based on advanced technologies foreseen for the future blankets (DEMO) and to validate design tools and performances;

• to demonstrate reliability for heat production and removal for future production of electricity;

• to complete the database used for the blanket design (neutronics, electromagnetics, thermo-mechanics and thermo-hydraulics).


• EU TBM concepts (HCBP and HCLL) to be tested in ITER :

• The EU test program foresees the fabrication and installation in ITER of 8 TBMs (4 TBMs per concept), installed/tested successively over the first 10 years of ITER;

• The first two TBMs have to be ready on day-1 of ITER operation (2017).

EU TBMs to be tested in ITERITER Test Port

(Equatorial plane)

TBMs

HCPB HCLL

Breeder Material i)Li4 SiO4 / Li2 TiO3 (pebble beds)ii)Pb-15.7Li (liquid metal)

Structural Material

Reduced Activation Ferritic- Martensitic steel: EUROFER

Coolant: Helium at 300-500°C, 8 MPa


HCPB-TBM integration in ITER port

FZK - EURATOM


Helium Coolant System for HCPB TBMs Same HCS for both HCPB and HCLL TBMs

FZK - EURATOM


M

MM

M

M

HCPB-TBM

He compressor

HXECONOMISER

FILTERM

CPS

M

MTES

M

MM

M

HEATER

He purge flow

p He 8MPa, 1.4 kg/s

p He 0.12 MPa, 0.6 g/spp H2 110 Papp HT+HTO 0.5 Papp H2O 0.4 Pa

Q2O to WPS

Impurities to WGPS

Q2 to TRS

Q2O to WPS

Q2 to TRS

HCS

H2, H2O in

H2 inp He 8 MPa, 5.3 mg/spp H2 300 Papp HT 0.3 Papp H2O 30 Pa

He CPS flow

HCS scheme with CPS+TES for Tritium control in the HCPB-TBM


HCPB-TBM behaviours

The HCPB-TBM will have the following design behaviours:• The TBM box will be constitutes by U-shaped first wall

(FW) made in Reduced Activation Ferritic Martensitic (RAFM) EUROFER steel;

• The ceramic breeder and the neutron multiplier will be both in form of pebble beds assembled in sub-breeder units He cooled by cooling plates;

• Ceramic pebbles (poli-dispersed) reference diameters are:– 0.25 - 0.63 mm for Lithium Orthosilicate OSi;– 0.6 -1.2 mm or Lithium Metatitanate MTi;

• Be pebbles reference diameter is 1 mm.


Heat Flux on FW 0.5 MW/m2

Neutron Wall Loading 2.4 MW/m2

Neutron fluence 7.5 MWa/m2

He inlet/outlet temperature 300/500 °C

He coolant operating pressure 8 MPa

Estimated pressure drops in the blanket module 0.403 MPa

Max. temperature in FW (steel) 552 °C

Max. temperature in CP (steel) 547 °C

Max. temperature in Ceramic Breeder 920 °C

Max. temperature in Beryllium 650 °C

Tritium Breeding Ratio (at breeder radial thickness) 1.14 (46 cm)

Pulse length long – steady state

HCPB DEMO blanket main design performances


Heat Flux on FW during H-H phase (peak) 0.15 (0.30) MW/m2

Heat Flux on FW during D-T phase (peak) 0.27 (0.50) MW/m2

Neutron fluence 0.30 MWa/m2

Neutron Wall Loading 0.78 MW/m2

He inlet/outlet temperature 300/500 °C

He coolant operating pressure 8 MPa

Estimated pressure drops in the blanket module 0.403 MPa

Max. temperature in FW (steel) 552 °C

Max. temperature in CP (steel) 547 °C

Max. temperature in Ceramic Breeder 920 °C

Max. temperature in Beryllium 650 °C

Tritium Breeding Ratio 1.14

Pulse length 400 - 3000 s

HCPB-TBM main design performances


HCPB-TBM to be installed in ITERCap

First Wall

Grid Attachment system

Back Plate - Manifolds

He PurgeDimensions (mm)

1208 (tor) x 710 (pol) x 600 (rad)Breeder Unit He in/outFZK - EURATOM

Box structure: EUROFER steel


Materials for the HCPB - TBM

Li4 SiO4 pebbles(Melt-Spraying fabrication; ∅

0.25 – 0.63 mm)

Li2 TiO3 pebbles(Extrusion fabrication

process, ∅

0.6 – 1.2 mm

Solid-Breeder Unit

HCPB - TBMBox structure: EUROFER ferritic-martensitic (low activation) steel

Be pebbles(Rotating electrode method, ∅

1 mm)

FZK - EURATOM


HCPB Breeder Unit

FZK - EURATOM


Comparison between HCBP-TBM and DEMO BBDue to the low neutron fluence no significant irradiation damages are expected in the TBM (only few dpa/y can be generated in steel at ITER neutron fluence). Only the operation of an international irradiation facility (IFMIF), in parallel to ITER, will provide irradiation data for DEMO design. Besides these limits, TBM tests in ITER are attractive due to the following considerations :

- the D-T neutron spectrum is typical of Fusion application;- the neutron flux is low but irradiate large blanket volume;- the volumetric heat generation in steel and pebble beds is considerable;- the surface heat flux due to plasma is considerable;- the magnet field and confinement are typical of Fusion Reactor;- the Plasma pulse lengths is sufficiently high (400 s up to 3000 s);- the Tritium to be handle is low but relevant for future application.


Tritium control for TBMs

The main goals of the tritium control for TBMs are the following:

• to demonstrate that the tritium production in the TBM is large enough to ensure tritium self-sufficiency by ‘extrapolation’ to future power reactors;

• to extract tritium from the TBM breeder and multiplier materials in efficient way during operation by associated systems (TES, CPS);

• to demonstrate that the tritium can be safely processed in the extraction circuits and associated systems (TES, CPS);

• to limit the tritium inventory in the breeder and multiplier materials to be potentially released from during accidents;

• to limit the tritium release from the TBM and associated systems into the environment (e.g. by anti-permeation barriers…) and thus limit the impact on the personnel;

• to check the tritium re-processing and storage circuit performances.


In ITER, the Tritium release total limit into the environment is fixed at 1 g/year (~27 Ci/d). The amount of Tritium released from TBMs into the environment, limited to only a fraction of the previous one, depends on the following parameters:

• permeation rate from TBM through the wall into the He coolant (to be determine on the base of geometrical characteristics of TBM and Permeation Reduction Factor (PRF) of steel surfaces;

• functional parameters of He purge flow and extraction efficiency of TES;

• functional parameters (Q species partial pressure, He mass flow etc.) and extraction efficiency of Cooling Purification System (CPS) of HCS;

• T leaks rate in the HCS components (e.g. circulator, HX etc.) and associated circuits (CPS, TES, TRS, ISS, IDS, TWS etc.)

Tritium release into environment


Comparison of Tritium levels in TES/CPS for HCPB-TBM and HCPB-DEMO

TES CPSHCPBTBM

HCPBDEMO

HCPBTBM

HCPB DEMO

T gener. per pulse (g/d) 0.1 385 - -

T perm. form purge gas (g/d) - - 12x10-6 12.6

He gas flow rate in TES (kg/s) 0.6x10-3 0.4 - -

He flow rate in CPS (kg/s) - - 5.32x10-6 2.4

He gas in/out temp. in TES(C) 300/450 400/500 - -

He in/out temp. in CPS (g/s) - - 500/50 500/300

He inlet pressure (MPa) 0.12 0.12 8 8

H2 partial pressure (Pa) 110 110 300 1500


R&D activities on ceramic breeder materials for TBMs


In the EU R&D programme for TBM, the following activities are foreseen for the ceramic breeder pebble fabrication:

• development and production of ceramic pebbles with fabrication route from Lab scale up to semi-industrial level;

• characterization of ceramic materials: microstructure, chemical and phase composition, density and porosity, mechanical properties (mechanical strength), compatibility with structure material (EUROFER), compatibility with the purge gas;

• definition of recycling process after reactor irradiation.

R&D on ceramic breeder pebble fabrication


Functional requirements• Ceramic pebbles have no structural function in the breeder blanket but

they must sustain the stresses induced under the reactor operating conditions (pressures, temperature and thermal gradients/cycling);

• Thermal stability of the ceramic beds during operation due to constant thermal conductivity and heat transfer parameters;

• Chemical stability of the ceramic pebbles at the maximum temperature with regards to lithium transport (vapour pressure) and material compositions (new phase formations);

• Chemical compatibility between the ceramic and the structural material (EUROFER steel), in the reference purge gas (He + 0.1% H2) and at the maximum interface temperature (550°C);

• Mechanical stability of ceramic pebble under neutron irradiation at operation conditions and for the required life-time;

• Sufficiently low Tritium Residence Time (TRT) (in the range of the operational temperatures) in the Li ceramics to minimize Tritium inventory;

• As low as possible activation under neutron irradiation, including activation of impurities.


• The selected option for the tritium breeding material of the EU Helium Cooled Pebble Bed (HCPB) breeder blanket concept is a ceramic breeder in the form of pebble beds;

• Lithium orthosilicate Li4SiO4 (OSi,) and Lithium metatitanate Li2TiO3 (MTi,) are considered as possible candidates for use in the ceramic breeder pebble beds;

• OSi (~0.25-0.63 mm pebbles) are produced by melting and spraying process at Schott AG, Mainz, in collaboration with FZK;

• MTi (~0.6-1.2 mm pebbles) are produced by extrusion- spheronisation-sintering process by the industrial firm Ceramiques Techniques et Industrielles (CTI), France in collaboration with CEA;

• The characterisation and optimization of the two materials is the subject of an intense R&D effort in the frame of the European HCPB Programme;

• Both materials, OSi and MTi are investigated in parallel.

Material options


OSi pebbles and cross sections (SEM)

FZK - EURATOM

D= 0.25 - 0.63 mm


MTi pebbles and cross sections (SEM)

D= 0.60 – 1.20 mm


In the EU R&D programme for TBM, both ceramic breeder pebbles (OSi and MTi) have been already fully characterized as the followings parameters are concerned:

• Pebble Density;• Grain Size;• Specific Surface Area; • Crush Loads;• Thermal Shock Behaviour;• Compatibility with Structural Materials; • Interaction with Hydrogen;• Interaction with Water Vapour (Surface Adsorption, Grain Boundary

Absorption, Dissolution Inside the Crystals);• Tritium Retention/Release;

PEBBLE CHARACTERIZATION


Both the ceramic breeder pebble beds (OSi and MTi) have been already fully characterized as the followings parameters are concerned:

• Pebble Bed Density and Packing Factor;• Pebble Bed equivalent Young’s Modulus;• Pebble Beds Thermal Creep;• Heat Transfer Properties (Thermal Conductivity, Heat Transfer

Coefficient);• Pebble Beds Thermal Cycling Behaviour;• Pebble Beds Powder Release and Pebble Fragmentation.

PEBBLE BED CHARACTERIZATION


Selection Criteria for breeder material

The selection of the best ceramic breeder for blanket application, under long-term neutron irradiation and heavy burn-up, will be performed comparing mainly the followings:

Tritium release properties and Tritium inventory;Irradiation resistance (at some tens of DPA); Thermal-mechanical behaviour of the pebble beds as far as swelling, thermal fatigue and creep resistances are concerned; Possible lost/change of thermal performances of the beds under irradiation;Cost for pebble productions;Possibility and cost for Li recycling.


OUT-OF-PILE TESTING


Helium facility for HCBP-TBM testing HEBLO

FZKHE-FUS3

ENEAHELOKA

FZKNominal pressure [MPa] 8 8 8

Mass flow [Kg/s] 0.175 0.35 – 1.4* 1.4Heating [MW] 0.115 0.21 – 1.0* 1.5Cooling [MW] 0.115 0.28 – 1.0* 1.5Max. He temp. [°C] 500 530 500Compressor head [MPa] 0.15 0.5 – 0.93* 0.93

Mock-up scale 1:8small

1:3 – 1:1*medium-large*

1:1large

* After HEFUS3 upgrading with new compressor, electric power supply and cooler


FZK - EURATOM

HELOKA facility


Vorgangsname

TBM Power SuppliesTBM PS ready f or operation

Experiments with air (leakages, welding procedures, etc.)Supporting structureHELOKA-HP/TBM

Main loop components (without circulator)Heat exchangerCoolerHeaterPipes (low temp)ValvesHangers

Safety valvesVacuum system

Air compressorAir loop - assemblyAir loop - ready f or operationTests with air

Helium related componentsPressure vesselsInterface HELOKA-TBMManuf actuting of Circulator by EFDA art. 7Assembly of circulator on HELOKA-HP Data Acquisition and Control (DACS)Interlock System (IS)DAC/IS Assembly , Commissioning & Inspection

HELOKA loop - Assembly endLoop Commissioning & InspectionStart TBM Exp. Prog.

TBM Power Supplies05/10

Experiments with air (leakages, welding procedures, etc.)Supporting structure

HELOKA-HP/TBMMain loop components (without circulator)

Heat exchangerCooler

HeaterPipes (low temp)

Valves11/10

Safety valvesVacuum system

Air compressor14/0914/09

29/02Helium related components

Pressure vesselsInterface HELOKA-TBM

31/0309/06

Data Acquisition and Control (DACS)Interlock System (IS)

20/0709/06

24/1124/11

Tri 1 Tri 2 Tri 3 Tri 4 Tri 1 Tri 2 Tri 3 Tri 4 Tri 1 Tri 2 Tri 3 Tri 4 Tri 1 Tri 2 Tri 3 Tri 4 Tri 1 Tri 2 Tri 3 Tri 4 Tri 1 Tri 22005 2006 2007 2008 2009 2010

HELOKA planning of fabrication


HE-FUS 3 PRESENT SCHEME

VACUUM

HOT TESTSECTION

PURIFICATION IN

HEATERCOLD TESTSECTION

HELIUM DISCHARGE SYS

HE-BOTTLES

HELIUM FILLING SYS

MIXER

E219/2 E219/3

FT228

E 240

COOLER

V 205 TANKE214

ECONOMIZERFT

212

PCV 248

S 260

FILTER

K200

PCV246

FV 230

MIXER

HV 251

FV 234

COMPRESSOR

HEFUS3 facility

ENEA - EURATOM


HE-FUS3 FACILITY

ENEA - EURATOM


HELICA MOCK-UP

ENEA - EURATOM

Top LVDT Electrical Leadthroughs

SCHNORR cup springs

Filling and monitoring tube

Flanged plug Lateral LVDTs


Out-of-pile thermal-mechanical testing of Li pebble beds in HELICA

ENEA - EURATOM

G. Dell’Orco , 14th Workshop on CBBI, Sept. 6-8, 2006, Petten, The Netherlands 37ENEA - EURATOM

HEXCALIBER MOCK-UP


Li4 SiO4 equivalent plastic strainTemperature distributions

Von Mises stress distributions

Box deformation

Be equivalent plastic strain

Thermal-mechanical calculations of HEXCALIBER performances

ENEA - EURATOM


The pebble bed out-of-pile thermal-mechanical testing in simulated TBM conditions will prosecute with the following experiments:

HEXCALIBER tests (in 2006-2007);

the breeder unit (BU) mock-up tests (> 2008);

the 1:3 scale TBM mock-up tests (> 2010);

the 1:1 scale TBM prototype tests (> 2013).

Future out-of-pile thermal-mechanical testing


ID Nome attiv ità

1 TESTS OF HCPB-TBM2 BENCHMARK TESTS ON HELICA AND HEXCALIBER 3 FABRICATION OF BU/FW MOCK-UPS4 TESTS ON BU/FW5 TESTS ON Frascati HITS6 TESTS ON FRAMATOME HEATRIC7 FABRICATION OF DEMONSTRATOR SCALE 1/38 TESTS ON DEMONSTRATOR SCALE 1/39 UPGRADING OF HEFUS3 COMPRESSOR AND HEAT EXCHANGER10 PROCUREMENT OF NEW COMPRESSOR AND HEAT EXCHANGER11 ASSEMBLY AND COMMISSIONING OF NEW COMPRESSOR AND HEAT EXCHANG12 TESTS OF HCLL-TBM13 EBBTF FABRICATION14 EBBTF COMMISSIONING15 FABRICATION OF SMALL SCALE MOCK-UP 16 TESTS ON SMALL SCALE MOCK-UP (BU/FW)17 FABRICATION OF DEMONSTRATOR SCALE 1/418 TESTS ON DEMONSTRATOR SCALE 1/4

S1 S2 S1 S2 S1 S2 S1 S2 S1 S2 S1 S2 S12004 2005 2006 2007 2008 2009 2010

Planning HEFUS3 for testing HCPB/HCLL TBM mock-ups


ID Task Name Durata Inizio Fine Predecessori

12 HeFus 3

Upgrading36.4 sett. ven 31/03/06 lun 11/12/06

3 Contractfinalisation

18.8 sett. ven 31/03/06 mer 09/08/06

4 TechnicalSpecif ication f or thenew TS piping andHEX ready

0 giorni v en 31/03/06 ven 31/03/06

5 Contract Award f ornew TS piping andHEX

0 giorni mer 31/05/06 mer 31/05/06 4FI+44 giorni

6 TechnicalSpecif ication f or thePower SupplySystem ready

0 sett. lun 10/04/06 lun 10/04/06

7 Contract Award f orthe Power SupplySystem

0 sett. mer 09/08/06 mer 09/08/06 6FI+88 giorni

89 Installation

activities18.8 sett. mar 01/08/06 lun 11/12/06

10 Piping f or new TSand HEX installed

0 sett. mar 01/08/06 mar 01/08/06 5FI+44 giorni

11 HEX installed 0 sett. mer 18/10/06 mer 18/10/06 5FI+100 giorni12 Power Supply

System installed0 sett. lun 11/12/06 lun 11/12/06 7FI+88 giorni

31/03

31/05

10/04

09/08

01/08

18/1011/12

mar 06 apr 06 mag 06 giu 06 lug 06 ago 06 set 06 ott 06 nov 06 dic 06 g

Planning HEFUS3 for upgrading


IN-PILE TESTING


In-pile-testing (1/2)In the EU R&D programme for TBM, the following irradiation campaigns on ceramic pebbles are foreseen as crucial issues for the final breeder material selection:

• EXOTIC-8 & EXOTIC-9/1 to study tritium release and tritium inventory in the OSi and MTi ceramics. The irradiation and PIE have been completed;

• Pebble Bed Assembly (PBA) to study the effect of neutron irradiation on the thermo-mechanical behaviour of the pebble beds at DEMO relevant levels of temperature and defined thermal-mechanical loads. The irradiation was completed and PIE will be finished in 2006. The experiments are supported by an extensive modelling effort and obtained irradiation data will be used for validation of the predictive tools for the pebble bed behaviour under irradiation.


• The HICU, high dose irradiation program, to start in 2006 and with first PIE results foreseen in 2009. Both OSi and MTi pebbles with different 6Li enrichment will be irradiated with the following aims:

– to check the irradiation resistance of the OSi and MTi ceramic pebbles at relevant temperatures and neutron equivalent (in term of ration between Li burn-up/dpa) spectra;

– to check the thermal-mechanical behaviour of constrained breeder pebble beds;

– to reach damage in OSi up to 20 dpa what represents about 1 FPY of DEMO operation.

In-pile-testing (2/2)


Breeder pebble-bed

Beryllium pebble-bed

Beryllium pebble-bed

1st containment:Eurofer-97 structure

Thermal Barrier 2:Eurofer-97

Thermal Barrier 1:Inconel718

Floating plate:Eurofer-97

Thermocouple tubes:AISI 321+Pt-clad inbreeder zone

Purge gas line (out)

Purge gas line (in)

2nd containment:AISI-316L structure

Al filler

Al filler

Neutron dosimeter

Self PowerNeutron detector

Pressure plate,Threaded ring,Sealing plate:all Eurofer-97

HHCCPPBB PPeebbbbllee--BBeedd AAsssseemmbblliieessHCPB Pebble bed assemblies


In the EU R&D programme for TBM is also foreseen the development of a modelling tool for the pebble bed theoretical computation to predict, adopting proper pebble bed mechanical constitutive sub- models in FEM commercial codes, the pebble bed thermo-mechanic behaviour under the test conditions.

This tool has to be validated by a benchmark exercise among EU Association (NRG, FZK, ENEA-DIN) on the base of the available thermo-mechanical experimental results.

The model will analyse the elasto-plastic and creep behaviors of both Li breeder ceramic and Be pebble beds.

At the present the first comparison of thermal fields is in progress with the experimental data from the HELICA out-of-pile experiments. The thermo-mechanical comparison is still in progress.

Future analyses and comparison are foreseen with the data from the HEXCALIBER test campaigns.

Thermo-mechanical modelling


Thermo-mechanical modelling of HELICA

UNIVERSITA' DI PALERMODINUNIVERSITA' DEGLI STUDI DI PALERMO

DIPARTIMENTO DI INGEGNERIA NUCLEARE





Mechanical and thermal symmetry

Helium heat transport in the cooling channels described by the steady state heat transport equation with a "frozen" velocity fieldBoundary conditions Tinlet , P and GTot

p=0.09 MPa Natural convection with airBoundary conditions Tair = 20°C

Forced convection with HeliumBoundary conditions T, P and G

( ) ( ) ( )2q r,T T J rρ′′′ =

Coulombian contact model at the interface bed-wall and bed-heater


THE HELICA STEADY STATE THERMO-MECHANICAL ANALYSESThermal field at middle section

1 2 3

4 5 6




200

300

400

500

600

700

800

900

0 60 120 180 240 300 360

Time [min]

Tem

pera

ture

[°C

]

Thermocouple 4Thermocouple 3Thermocouple 2Thermocouple 1

THE HELICA STEADY STATE THERMO-MECHANICAL ANALYSESResults at 55 mm





Heat ramp step 2 Heat ramp step 3

Heat ramp step 4 Heat ramp step 6


Mean stress (MPa) in OSi beds at 060 mm from FW



Mean creep compaction strain (%) in OSi beds at 060 mm from FW




Mean total compaction strain (%) in OSi beds at 060 mm from FW


Two ceramic breeder materials (OSi and MTi) have been extensively characterised for breeder blanket application in not irradiated conditions. The fabrication and recycling processes have been defined and improved up to semi-industrial level (with industrial partnership). Minor differences between them have been found in the non nuclear behaviour (e.g. Li density, thermal expansion, crush load, creep, etc.) but no critical issues connected to one of the materials.The development of a FEM theoretical model for the computation of the pebble bed performance is still in progress.A benchmark exercise among EU Associations (NRG, FZK, ENEA- DIN) was launched to compare the available experimental results on the HELICA mock-up.The first comparison between the numerical predictions and experimental results of the thermal fields of HELICA seems encouraging whilst the comparison with stain/stress fields is still in progress.

Conclusions (1/2)


Only limited data are available for the irradiation impact on the ceramics behaviour and on thermal-mechanical pebble bed properties. The results from HICU irradiation program, available in 2009, will be crucial for the selection of the reference material. If both breeder materials will show acceptable irradiation performance, other aspects (like simplicity/easiness of fabrication/recycling processes, cost of the materials) will be taken into account for the final selection.As far as ITER TBM is concerned, the present plan foresees the testing of both materials (OSi and MTi) to be tested also simultaneously in the same TBM but in different Breeder Unit.In case that the irradiation performance will be found unsatisfactory for both materials, a third material will be proposed (Li Meta-zirconate). This material, studied in the past EU R&D Programme, was taken off in 1998 because is shows stronger (but still acceptable for fusion application) activation than OSi and MTi.

Conclusions (2/2)

overview on the eu r&d for ceramic breeder materials for ... · 14th workshop on cbbi, sept....

Documents