What can be measured in and what can be learned from RF ITER-TBM

Fusion blankets in RF – from TBM to DEMO

Y.S. Strebkov, I.R. Kirillov, D.M. Obukhov,V.G. Kovalenko, B.V. Kuteev

Kuteev_BV@nrcki.ru

IAEA DEMO-3, 11-15 May 2015, Hefei, China

2

Goals

Development of engineering and technology potential for

mastering the fusion nuclear science and technology needed for design

and construction of blankets and supporting them systems providing

tritium technology, heat transfer, operation control etc for DEMO,

tokamak based Fusion Neutron Sources and Fusion-Fission Hybrid

Systems

We consider FFHS as a parallel to ITER activity that may improve theFusion Nuclear Science and Steady State Technologies being capable toaccelerate the DEMO design after successful burning plasma experiment

3

Fusion reactor blanketIncineration of nuclear waste

Nuclear Fuel Breeding

High temperature heat

Tritium breeding

Safety

Pure Fusion FFHS

ITER

DEMO-S

Technology demonstration on TBM

TBR>1

PHP

DEMO-FNS

Technologydevelopment

TBR>1?

Technologydevelopment

?

Blanket research directions

4

DEMO Fusion Blankets in RF (1)

In 1998-2000 RF has made a design of a demonstration fusion reactor DEMO-S withcontinuous plasma burn. Two types of blanket were considered: helium cooled ceramicbreeder () blanket and lithium self-cooled one (LSC), where lithium acts as coolant andtritium breeder.

Major parameters of Russian DEMO-S reactor

Parameters ValuePlasma major radius (m) 7.8Plasma minor radius (m) 1.5Toroidal field on plasma axis (T) 7.7Fusion power (GW) 2.44Average/maximum fusion neutron load on the FW(MW/m2) 2.5/3.4Average/maximum heat load on the first wall surface(MW/m2) 0.4/0.7

Plasma elongation 1.85Plasma triangularity 0.4

Plasma pulse duration (days) 1-10

5

DEMO Fusion Blankets in RF (2)

•LSC blanket was evaluated as the best option capable of providing high efficiency of heatto electricity conversion, high tritium breeding (TBR), the capability of keeping high TBRduring reactor operation by online 6Li control and compensation of breeder material burnup. This blanket concept requires a solution of a number of critical technical issues.

•Analysis of another blanket concept – lead lithium ceramic breeder (LLCB) proposed byIndian specialists was performed for RF DEMO-S reactor in 2009-2010. Lead – lithium(LL) eutectic and lithium ceramics are used for tritium breeding, LL is also cooling thebreeding zone and helium is cooling the blanket first wall and its structure.

•Calculations showed that LLCB blanket of DEMO-S reactor provides reasonably highTBR at radial dimensions 500/450 mm for outboard/inboard sections – 3-D TBR=1.16 atLL and CB 90% enrichment of 6Li. This value is higher than for pure lead-lithium orceramic breeder blankets.

•DEMO-S ceramics and pure lithium blankets used beryllium (Be) for neutronmultiplication. In lithium blanket this was caused by chosen limitation on blanket radialdimensions. Absence of Be in LLCB blanket is another advantage of this concept.

6

DEMO Fusion Blankets in RF (3)

•At LL inlet/outlet temperatures 325/550°С efficiency of heat to electricity conversion maybe around 38% (steam turbine) – the same as for pure Li blanket, where these temperatureswere 350 and 560°С correspondingly. LL outlet temperature might be further increased to~ 700°С with the use of SiC as duct walls or duct insertions and helium cooling ofstructure. The estimated efficiency of heat to electricity conversion at inlet/outlet LLtemperatures 460/700°С was higher than 40%.

•Life time of this blanket with TBR>1 is higher than that of ceramic blanket due topossibility of online LL enrichment during exploitation without blanket replacement.

•The reason for RF to develop this blanket type as the Test Blanket Module (TBM) forITER (as a Collaborator to the Leader – Indian Team) is the possibility to develop and testsimulteneously both lithium ceramics and liquid metal technologies.

7

TBM development in RF

• TBM design:- Participation in IN LLCB TBM conceptual design.- Development of RF LLCB TBM conceptual design.

• DEMO design similarity is provided with:- Choice of the same materials: ferritic steel as structure

material, Li ceramics - Li2TiO3 60% enriched with 6Li,liquid metal – PbLi eutectic enriched with 6Li (90%).

- Physical and geometrical similarity (FW and TBMstructure cooling with He, downward PbLi flow near the FW,

and upward PbLi flow in hydraulically parallel ducts/sub ducts – in the rest part of the breeding zone).

• R&D in support of the design:- TBM mock-ups thermo hydraulic tests in magnetic field

(computer codes development/verification).- PbLi technology development including corrosion tests.- Tritium monitoring system development and testing.- Tritium extraction technique development.- Hydrogen isotopes permeation tests.

8

ТВМ results

Design of TBM construction with ceramic breeder (CB) and liquid metal coolant (LMC)

1-first wall; 2-body covers; 3- partition separating flow zones of LMC; 4, 5-zones of up/down flows of LMC; 6, 7-input/bypass manifold for LMC; 8, 9-input/output pipe brunch for LMC; 10, 11- input/output pipe brunch for gas coolant; 12, 13- input/output pipe brunch for gas carrier; 14-unit with ceramic breeder; 15-reinforcing plates of gas pipe brunch units; 16-bimetal adapter; 17- mechanical support;18-electric connector

Longitudinal section of CB LMC TBM

1-first wall; 2- protective coating; 3- partitionseparating flow zones of LMC; 4-ducts of downflow zone of LMC; 5-inter duct partition of downflow zone of LMC; 6- ducts of upward flow zoneof LMC; 7- inter duct partitions of upward flowzone of LMC; 8-unit with ceramic breeder; 9-partition of of upward flow zone of LMC andoutput pipe bruch of gas coolant; 10-partition inunit of gas pipe branches; 11-back plate of thebody; 12-mechanical support; 13-anti-torque lock;14-terminal electroisolating block; 15-input pipebranch for gas coolant; 16- reinforcing plates of gaspipe brunch unitCross-section of CB LMC TBM

Distributions of volumetric energy source in the TBM components

Temperature distribution in TBM

9

Firs

t div

erto

r re

plac

emen

t

TBM installation in ITER 2,5 6,5 10 11 20

R&D, Design Development of

manufacturing technology for

TBM Mockups manufacturing

and testingTBM delivery EM-TBM

Fisr

t IT

ER

shut

dow

n at

the

DT

phas

e

NT-TBM

TM-TBM

INT-TBM

23 28

EM-TBM- study of parts and systems behavior in EM transients;- study of effects of metallic parts of TBM on the plasma confinement;- collecting the information needed for licensing the TBM at the nuclear stage.

NT-TBM- - study of TBM behavior in fusion neutron environment and tritium breeding processesTM-TBM- study of TBM parts and systems behavior under temperatures typical for fusion reactor DEMO

INT-TBM- demonstration of operation of DEMO blanket prototype at nuclear stage of ITER operation (generation of high temperature heat and tritium technology)

3 15

Post irradiation studies

Roadmap of RF program on development and testing the DEMO-ITER TBMs

10

ТВМ activities

1. Modeling and design works:- TBM design including development of 3D models;- Matching of databases on material properties and engineering parameters

used in optimization accounts;- Complex of neutron physics, thermo-hydraulic and strength property

accounts etc.;

2. R&D justifying design and technology solutions for TBMs:- MGD, thermo-hydraulics and effects of thermo-gravity convection of lead-

lithium eutectic in magnetic field;- development of technology for lead-lithium eutectic and corrosion

experiments;- penetration of hydrogen isotopes through structural materials;- tests of mockup for TBM tritium monitoring system in IVV-2M reactor;- Reactor loop experiments on IVV-2M (corrosion resistance, permeability

and extraction of tritium, etc.)

11

R&D results (thermo hydraulic tests)

• Mock-up geometry is similar to 1/3 of the breeding zone in toroidal and 1/3 in radial directions.• Poloidal ducts are divided into 2 and 3 sub ducts in the toroidal direction. • Tests characteristic parameters: NaK, B=1 T, Ha=950-1500, N=60-2000.• Experimental data were obtained for flow rate distribution in parallel ducts/sub ducts, electric potentials on side walls, pressure drop, velocity distribution and compared with results of FLUENT code developed by IN Team.

Fraction of flow in ducts 1 and 2 for different flow rates Side wall electric potential difference in

ducts 1 and 2, flow rate 0.55 kg/s (2.3 m3/h)

NaK loop

Mock-up (collector and 2 parallel ducts)

12

ТВМ results (ctn.)

NIIEFA facility LMC -loop

Moscow Energy Institute

PEI Obninsk

13

ТВМ results (ctn.)

Non-reactor prototype “TMS”

Test bed “IPIV-М”

Parts of non-reactor liquid metal loop facility

Technology circuit of test bed “RITM-FM”

Mockup of TMS for reactor tests

14

R&D results (thermo gravitational convection) (1)

Single poloidal duct: - Cross-section dimensions 20(rad) x 60(tor) mm2, length 2 m.- Magnetic field - 1 T.- Uniform length of magnetic field zone - 520 mm.- Flow direction – downward/upward.- One-sided/two-sided heating, heating length 703 mm,

heat flux q = 0 ÷ 35 kW/m2

-Characteristic parameters: Re = 50 000, Ha = 0 ÷ 800, Gr = 0 ÷108

Results:The significant non-uniformity of the flow velocity and temperature distribution was found. External magnetic field increases these non-uniformities in certain conditions and leads to the development of large-scale structures in the flow, which are the result of combined action of electromagnetic and gravitational forces. Heat transfer intensification and development of low frequency temperature fluctuations of great amplitude are found in these conditions.

Test section in mercury loop

15

R&D results (thermo gravitational convection) (2)

• Heat transfer intensification at one-sided heating with q1= 35 kW/m2 (Grq=4.0108), Re = 3·104 and Ha increasing: 1) На=0; 2) 120; 3) 300; 4) 500; 5) 800

- Dimensionless temperature profiles over ductheight;- Nut, Nul – Nusselt numbers for turbulent and laminar flow

• Influence of thermo gravitational convection (buoyancy effects) on temperature fluctuations intensity- Maximum intensity of temperature fluctuations (RMS) for downward flow with one-sided heat flux: 1, 3 – in the flow core; 2, 4 – on the side wall; Re= 3·104 (1, 2); Re=5·104 (3, 4)

0 0.5 1

y/ b-0.1

0

0.1

0.2

0.3

0.4

1/NuT

1/Nul

- 1- 2- 3- 4- 5

16

R&D results (corrosion tests)

Tests conditions:- Molybdenum crucible with inner diameter 50 mm and height200 mm loaded with 1.8 kg of lead-lithium eutectic alloy, 550oC,

rotating speed 17 rot/s, exposition of samples from EUROFER 97(uncoated and coated) up to 3500 hours. Samples are assembled as six 60o sectors of the ring 3.8 mm thick.

Test results:- Uncoated samples at 550oC and Pb-15.7Li velocity 0.14 m/sduring 3000 hours had thickness loss 146 µm, i.e. 430 µm/y. It is within the interval for similar data in literature. - Corrosion rate of samples coated with aluminum implanted withelectron beam and oxidized are two times less than uncoated ones. - Experimental data obtained by method of rotating disk agreewith the results of loop testing if radial velocity of liquid near the disk is used for comparison.

Rotating Disctest sections

Samples for corrosion tests

17

R&D results (PbLi technology)

Loop facility with circulating lead-lithium alloy is being manufactured in NIIEFA.

• Major goals of the facility: - Technology development for PbLi eutectic alloy preparing. - Technology development for alloy cleaning.- Elaboration of methods for alloy impurities control.- Corrosion tests of structure materials at the conditions of TBM.- Long term testing (thousands of hours).

• Facility main parameters:- Working fluid – Pb-15.7Li alloy.- Inventory – about 30 liters.- Flow rate – up to 500 liters/second.- Working temperature – 350-550oC.- Test sections for corrosion tests: 1 – velocity 7 cm/s, T = 350-550oC; 2 – velocity 7 cm/s,

T = 550oC; 3 – velocity 50 cm/s, T = 550oC.- Equipment for alloy manufacturing (up to 1000 kg).- Alloy cleaning – cold trap with magnet.- Alloy impurity control – electrochemical based sensor, plug indicator, sampler.

18

Conclusions (Pure fusion blankets)

TBM R&D learned:- to investigate the permeation of structural material by hydrogen isotopes; - to measure the tritium activity in the lithium carbonate tablets;- to conduct the in-pile tests of the TBM tritium monitoring system (TMS) channel mock-up.

TBM R&D results:- investigation results of the RUSFER hydrogen isotopes permeation;- measuring methods of tritium activity in the lithium carbonate tablets;- upgraded facility for Functional in-Reactor Investigations of Tritium-breeding Models (RITM-FM facility);- the TBM TMS channel mock-up may be used to determine flow tritium by irradiating samples of other lithium compounds.

Importance for TBM design:- experimental basis for the design development and manufacturing the TBM TMS;

Conclusion (what needs to be investigated):- the hydrogen isotopes permeation of RUSFER welded joints;- the lithium-lead eutectic technology development;- the tritium extraction from the lithium-lead eutectic;- the lithium-lead eutectic compatibility with structural materials.

19

Two nuclear fuel cycles are considered

U-Pu

1Pu+1T per 1n(DT)

Th-U

0.6U+1T per 1n(DT)

Hear exchanger, primary loop

Hear exchanger, secondary loop

Heat transfer

Molten salt85% FLiNaK+15% ThF

4580ºС 5.86 кг/с550ºС

1 bar

Molten salt92% NaBF4+8% Na

F 539ºС480ºС

1.7 kg/s

140ºС10 bar

water20ºС

Molten salt blanket module Thermal power 175 kW

Primary loop

Secondary loop

Cooler

Drain vessel

Storage

NRC “Kurchatov Institute”

pump

Solid blanket module

20

HB Option К(T) К(Pu)

MS (LiF+BeF2+UF4) density 2.3 g/cm3,Li - enriched (Li6 – 100%)

1.04 0.098

Line 1: Pb; Lines 2-5: MS (LiF+BeF2+UF4) density 2.3 g/cm3, Li – (Li6

– 7.5%)0.47 0.45

Line 1: 70% UN + 30% Pb (volume)Lines 2-5: MS (LiF+BeF2+UF4) density 2.3 г/см3,

Li - enriched (Li6 – 50%)

1.11 1.00

Lines 1,2– UN as shell-less fuel elements, U = U-238Li - natural (Li6 – 7.5%) shell-less

1.44 0.78

Lines 1,2– UO2 as fuel elements, U = 0.7% U-235 + U238Canal shell thickness 0.5 cm,

Li – enriched (Li6 – 50%)

0.94 1.35

Hybrid Blanket Options

Line 1 2 3 4 5

Section of blanket chanals

20

21Hybrid blanket simulations

1. The simulations suggest capability to reach sufficient tritium and Pu breeding ratio of ~1 per fusion neutron in hybrid blanket with depleted uranium.

2. Implementation of uranium and lithium containing molten salts without additional concentrated fuel (UN, UO2, for example) does not allow sufficient breeding ratio for T and Pu

3. Placement of UN or UO2 in a molten salt blanket requires high areal density of U in it that is a challenge for further design activity

4. Using the UN or UO2 as uranium containing material and Li2O as lithium containing material provides a reasonable level of T and Pu breeding. This option requires a detailed design

5. All options of HB provide sufficient tritium breeding ratio (Кт ~ 1) only having high level of Li-6 enrichment

21

22

Conclusions (Hybrid blankets)

HB design R&D learned:- Fusion Neutron Source is required for licensing support of hybrid devices and pure fusion systems.-neutron balance is critical for any blankets, it defines structural and functional materials and radial structure of the blankets.-blankets with molten salt and heavy water solutions of fuel are attractive as continuous processing options, however significant upgrade of technology level is needed in nuclide separation, corrosion, permeation, solubility. --incineration blankets require the neutron source intensity lower than that of fuel breeding blankets, this provides the priority position to those in RF; additionally, NE needs in Russia correlate with incineration of long life radio-nuclides.HB R&D results:- Concepts of HB using solid and liquid fuels are proposed;-Choice of structural material was made for the fusion neutron wall loading of 0.2 MW/m2 and radiation damage level below 20 dpa.

Importance for HB design: Technical basis for fusion blankets;

Conclusion (what needs to be investigated):-High plasma loadings on the first wall require an upgraded blanket design for DEMO.-Fissile nuclides in blanket reduce the surface needed for tritium breeding with TBR>1.-Combined incineration and tritium production in FFHS may simplify the blanket of fusion reactors

23

References

[1] Sokolov, Yu.A., et al., “Russian DEMO plant study”, Fusion Engineering and Design, 41 (1998) 525.

[2] Shatalov, G.E., et al., “Russian DEMO-S reactor with continuous plasma burn”, Fusion Engineering and Design, 51-52 (2000) 289.

[3] Kolbasov, B.N., et al., “Russian concept for a DEMO-S demonstration fusion power reactor”, Fusion Engineering Design, 83 (2008) 870.

[4] Kumar, E. Rajendra, et al., “Preliminary design of Indian Test Blanket Module for ITER”, Fusion Engineering and Design, 83 (2008) 1169.

[5] Kirillov, I.R., et al. “Lead – Lithium Ceramic Breeder Blanket for Russian Thermonuclear Reactor DEMO-S”, 25th IAEA Fusion Energy Conference (FEC 2014) St Petersburg, Russian Federation, 13 - 18 October 2014, FIP/P7-14.

[6] Wong, C.P.C., et al., “Overview of liquid metal TBM concepts and programs”, Fusion Engineering and Design, 83 (2008) 850.

[7] Leshukov, A.Yu., et al., ‘Design development and analytical assessment of LLCB TBM in Russian Federation during 2012–2013”, Fusion Engineering and Design, 89(2014) 1232.

[8] Satyamurthy, P., et al., “Experiments and numerical MHD analysis of LLCB TBM Test-section with NaK at 1 T magnetic field”, Fusion Engineering and Design, 91(2015) 44.

[9] Kirillov, I.R., et al., “Buoyancy effects in vertical rectangular duct with coplanar magnetic field and single sided heat load”, Fusion Engineering and Design, in print.