# Presentation: 919879

## Fusion Nuclear Technology Research and Opportunities for ITER Utilization

- Neil B. MORLEY and Mohamed ABDOU
- University of California, Los Angeles
**Fusion Power Associates**
**Annual Meeting and Symposium**
**Washington D.C.**
**October 11 and 12, 2005**

## Fusion Nuclear Technology (FNT)

**FNT Components and Materials from the edge of the Plasma to TF Coils**** ****(Reactor “Core”)**

- 1. Blanket Components (FW)

- 2. Plasma Interactive and High Heat Flux Components

- 3. Vacuum Vessel & Shield Components

- 4. Tritium Processing Systems

- 5. Instrumentation and Control Systems

- 6. Remote Maintenance Components

- 7. Heat Transport and Power Conversion

- a. divertor, limiter

- b. rf antennas, launchers, wave guides, etc.

**Other Components affected by the Nuclear Environment**

*Fusion Power & Fuel Cycle Technology*

## Fusion Nuclear Technology Critical Issues for Fusion Energy

**Tritium Supply & Tritium Self-Sufficiency**
- High Power Density
- High Temperature
- MHD for Liquid Breeders / Coolants
- Tritium Control (Permeation)
- Reliability / Availability / Maintainability
**Testing in Fusion Facilities**

## DT fusion is usually depicted to laymen by the reaction in the plasma

- n

**Physics**

**Confinement**
**Current Drive**
**Heating**
**...**

- _Tritium Consumption in Fusion is HUGE! Unprecedented!_
- 55.8 kg per 1000 MW fusion power per year

**Inexhaustible**
**Limitless**

## Tritium supply for the development of fusion – 

- Tritium supply for the development of fusion –
- where does it come from?

- _Conclusions_
- Availability of **tritium supply** for fusion development beyond ITER first phase is an issue
- Large power D-T facilities must breed their own tritium *(this is why ITER’s extended phase was planned to include the installation of a tritium breeding blanket)*
- FW/Blanket are necessary in the **near term **to allow continued development of D-T fusion

- _Production & Cost:_
**CANDU Reactors:**** ****27 kg**** from ****over**** ****40 years, ****$30M/kg ****(current)**** **
**Fission reactors:**** ****2–3 kg / year. ****at a cost of ****$84M-$130M per kg****, per DOE Inspector General***

## The DT FUSION ENERGY picture requires a closed fuel cycle and nuclear technology

- n

**Physics**

_**Blanket / Shield Components and Materials:**_
**Absorption**
**Activation**
**Multiplication**
**Energy Extraction**
**Shielding**
**R/A/M**

_**Tritium Fuel Cycle:**_
**Processing**
**Decay**
**Permeation**
**Inventory**

## Λr = Required tritium breeding ratio
Λr is 1 + G, where G is the margin required to account for :
tritium losses, radioactive decay 
inventory in plant components
inventory in tritium processing system
inventory stockpile for outages and for start-up of other plants 
Λr is dependent on many system physics and technology parameters.

Λa = Achievable tritium breeding ratio
Λa is a function of technology, material and physics requirements, e.g.
Efficient energy extraction
FW armor and thickness
Conducting shells, embedded coils, heating ports, etc.
Reliability/maintainability concerns

- Λ*r** is 1 + G, where G is the margin required to account for :*
- tritium losses, radioactive decay
- inventory in plant components
- inventory in tritium processing system
- inventory stockpile for outages and for start-up of other plants** **
- Λ*r** *is dependent on many system physics and technology parameters.
**Λ*****a***** = ****Achievable ****tritium breeding ratio**
- Λ*a* is a function of technology, material and physics requirements, e.g.
- Efficient energy extraction
- FW armor and thickness
- Conducting shells, embedded coils, heating ports, etc.
- Reliability/maintainability concerns

*Tritium Self-Sufficiency* : Λ*a** > *Λ*r*

## Tritium inventory in processing systems and reserves are closely tied to fueling rate and fractional burn-up in plasma – strong influence on required TBR: Λr 
3D Analysis of current worldwide FW/Blanket concepts accounting for plasma support systems estimates an achievable TBR: Λa ≤  1.15
Integral neutronics experiments in Japan and the EU showed that calculations consistently OVERESTIMATE experiments by an average factor of ~ 1.14

**3D Analysis of current worldwide FW/Blanket concepts accounting for plasma support systems estimates an achievable TBR:**** ****Λ*****a***** ≤  1.15**
**Integral neutronics experiments in Japan and the EU showed that ****calculations**** consistently ****OVERESTIMATE**** ****experiments**** by an average factor of ~ ****1.14**

- Current physics and technology concepts lead to a “narrow window” for attaining
- tritium self-sufficiency for DT fusion energy

- td = doubling        time

- td=10 yr

- td=5 yr

- td=1 yr

- Required TBR

- Fractional burn-up [%]

- “Window” for Tritium self sufficiency

- Fusion power  - 1.5GW
- Reserve time - 2 days
- Waste removal efficiency - 0.9
- (Sawan and Abdou, ISNFT-7)

## Physics and Technology R&D partnership needed to determine the potential for achieving “Tritium Self-Sufficiency”

**How do we Establish the conditions governing the scientific feasibility of the D-T cycle, i.e., determine the ****“phase-space”**** of plasma, nuclear, material, and technological conditions in which tritium self-sufficiency can be attained**
**R&D on FW/Blanket/PFC and Tritium Processing Systems that emphasize:**
- Understanding and predicting behavior of components and materials in the integrated fusion environment under relevant conditions
- Minimizing Tritium inventory in components
- Faster tritium processing system, particularly processing of the plasma exhaust
- Improve reliability of tritium-producing (blanket) and tritium processing systems
**R&D on physics concepts and operating modes that:**
- Maximize tritium fractional burn-up
- Reduce the requirements on space needed in the breeding region for heating, stabilization coils and conductors, etc.
- Ease peak requirements on surface heat loads and disruptions loads, etc.

## A technology/physics partnership is clearly already a part of ITER

**Many FNT components & capabilities needed for ITER basic machine**

- 1. Blanket Components
- 2. Plasma Interactive and High Heat Flux Components
- a. divertor, limiter
- b. rf antennas, launchers, wave guides, etc.
- 3. Vacuum Vessel & Shield
- 4. Tritium Processing Systems
- 5. Instrumentation and Control
- 6. Remote Maintenance
- 7. Heat Transport and Power Conversion

***But FEW technology solutions for ITER are compatible with TRITIUM SELF-SUFFICIENCY and ENERGY NEEDS***

## The ITER Test Blanket Module (TBM) Program is a vehicle for utilizing ITER to advance the scientific principals of tritium self-sufficiency!

***“******The ITER should serve as a test facility for neutronics, blanket modules, tritium production and advanced plasma technologies. The important objectives will be the extraction of high-grade heat from reactor relevant blanket modules appropriate for generation of electricity.”***
- —The ITER Quadripartite Initiative Committee (QIC), IEA Vienna 18–19 October 1987

- n

- ITER

**Studying burning plasma physics **

**Studying breeding & energy relevant technologies**

***“******ITER should test design concepts of tritium breeding blankets relevant to a reactor. The tests foreseen in modules include the demonstration of a breeding capability that would lead to tritium self sufficiency in a reactor, the extraction of high-grade heat and electricity generation.”***
**—**SWG1, reaffirmed by ITER Council, IC-7 Records (14–15 December 1994), and stated again in forming the Test Blanket Working Group (TBWG)

- ITER’s Principal Objectives Have Always Included  studying ENERGY relevant technologies and materials

## The TBM in ITER is essential to: 

- Perform first wall and tritium breeding module experiments to advance the understanding of the competing requirements of tritium self-sufficiency, extraction of high grade heat, and controlled, ignited plasma operation.

- TBM Mission

- The TBM in ITER is essential to:

**Achieve a key element of the ITER Mission *****“demonstrate the scientific and technological feasibility of fusion power for peaceful purposes”****** ***
**Achieve the most critical milestone in fusion nuclear technology research: testing in the integrated fusion environment. **
**Resolve the critical “tritium supply” issue for ignited plasma experiments and fusion development beyond ITER - ****and at a fraction of the cost to buy tritium for a large D-T burning plasma**
**Access R&D information from much larger ($10-20M per year) blanket/PFC programs (EU and Japan) and other international partners**
**Maximinize the return on the >$1B of US investment and capitalize on the >$10B of investment by international partners in ITER**** **

## TBM Preparation and R&D is proceeding aggressively in the International Community

**Several TBM proposals have**
**been made by ITER Parties:**
- Helium-cooled Li-based Ceramic/Beryllium TBM (4 variations)
- Helium-cooled liquid Lithium-Lead TBM (3 variations)
- Water-cooled Li-based Ceramic/Beryllium TBM (1 variation)
- Liquid natural Lithium TBM (2 variations)

***View of a typical TBM test port cell arrangement***

***TBM location in ***
***a ITER test port***

## ITER plan includes the TBM – Activities are coordinated by the Test Blanket Working Group

**TBMs are to be installed from the first day of****H-H operation to check interfaces & main ****operations, compatibility with ITER operations ****and to support to safety dossier**

**3 Midplane ports are reserved for TBM use, as ****well as space at the port cell, TCWS building, tritium building, and hot cell for necessary ancillary systems such as coolant loops, tritium processing, etc.**

## ITER Environment for TBM Experiments

- large geometry of the test ports. (maximum height of TBM ~ 2m, similar to the size of typical blanket modules in a power plant);
- plasma exposure with typical particle loads and off normal plasma events;
- strong magnetic field (~ 4 T), same order of magnitude as in power plants;
- similar neutron energy spectrum as in power plants, however lower neutron flux (~25- 30 % of neutron wall loading in DEMO plant) and much lower fluence;
- generation and confinement of radioactivity

## US TBM Selected Concepts

- 1. The Dual-Coolant Pb-17Li Liquid Breeder Blanket concept with self-cooled Pb-Li breeding zone and flow channel inserts (FCIs) as MHD and thermal insulator

- -- Innovative concept that provides “pathway” to higher outlet temperature/higher thermal efficiency while using ferritic steel.

- -- US lead role in collaboration with other parties (most parties are interested in Pb-Li as a liquid breeder, especially EU and China).

- -- Plan an TBM that will occupy half an ITER test port with corresponding ancillary equipment.

- 2. The Helium-Cooled Solid Breeder Blanket concept with ferritic steel structure and beryllium neutron multiplier, but without an independent TBM

- -- Support EU and Japan efforts using their TBM structure & ancillary equipment

- -- Contribute only unit cell /submodule test articles that focus on particular technical issues

## Dual Coolant Lead-Lithium (DCLL) FW/Blanket Concept 

***Idea of “Dual Coolant” concept –  ******Push towards higher performance with present generation materials (FS)***
**Ferritic steel first wall and structure cooled with helium**
**Breeding zone is self-cooled Pb-17Li**
**Structure and Breeding zone separated by SiCf/SiC composite *****flow channel inserts (FCIs)***** that**

**Self-cooled Pb-17Li ****Breeding Zone**

**He-cooled steel****structure**

**SiC FCI**

**DCLL Typical Unit Cell**

**Provide thermal insulation to decouple Pb-17Li bulk flow temperature from ferritic steel wall**
**Provide electrical insulation to reduce MHD pressure drop in the flowing liquid metal**
***Pb-17Li exit temperature can be significantly higher than the operating temperature of the steel structure ************ High Efficiency***

## FW He Coolant Manifolds

- FW He Coolant Channels

- Pb-Li Outlet Pipe

- Pb-Li Inlet Pipe

- Pb-Li Inlet Manifold

- Plasma Facing First Wall

- Pb-Li Flow Separation Plate with He coolant Channels

- FCI

- Pb-Li Inlet Flow Channel

- Pb-Li Return Flow Channel

- Bottom Plate He Coolant Channels

## Helium-Cooled Ceramic Breeder (HCCB) Blanket/First Wall Concept for TBM

***Idea of “Ceramic Breeder” concepts –  ******Tritium produced in immobile lithium ceramic and removed by diffusion into purge gas flow***
**First wall / structure / multiplier /breeder all cooled with helium**
**Beryllium multiplier and lithium ceramic breeder in separate particle beds separated by cooling plates**
**Temperature window of the ceramic breeder and beryllium for the release of tritium is** a **key issue for solid breeder blanket.**** **

***Schematic view of an example ITER HCCB ******test blanket  submodule****** showing typical configuration layout of ceramic breeder, beryllium multiplier and cooling structures and manifolds***

**Thermomechanical behavior of breeder and beryllium particle beds under temperature and stress (and irradiation) loading affects the thermal contact with cooled structure and impacts blanket performance**
**Nuclear performance and geometry is highly coupled and must be balanced for tritium production and temperature control**

## Ceramic Breeder TBM: Inserting “US” unit cells into the EU HCPB structural box

## Specific TBM Test Objectives in ITER

- validation of Tritium breeding predictions
- validation of Tritium recovery process efficiency, tritium control and inventories
- validation of thermofluid predictions for strongly heterogeneous breeding blanket concepts with volumetric heat sources and strong MHD interactions
- demonstration and understanding of the integral performance of the blanket components and material systems

## Summary Remarks

- There are many remaining challenging FNT issues that need to be resolved for successful fusion development
- The D-T cycle is the basis of the current world plasma physics and technology program. If the D-T cycle is not feasible the plasma physics and technology research would be very different.
**“****Tritium self-sufficiency”** is a complex issue that depends on many system physics and technology parameters / conditions.
- Availability of external **tritium supply** for continued fusion development beyond ITER’s first phase is an issue
- There is only a “window” of physics and technology parameters in which the D-T cycle is feasible. We need to determine this “window.”
- Conducting an effective Test Blanket Module **(TBM)** program is one of the main objectives of ITER and necessary to advance the understanding tritium breeding and tritium self sufficiency in fusion systems
**ITER will be the first real opportunity to apply the results of R&D from the past 30 years on many aspects of blankets, materials, PFC, etc.**