a methodology for evaluating progress toward an attractive fusion energy source

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A methodology for evaluating progress toward an attractive fusion energy

source

US/Japan Workshop on Fusion Power Plant Studies

5-7 March 2008

M. S. Tillack, L. M. Waganer

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Why do we need a methodology for evaluating progress?

Metrics are needed to quantify progress and the value of fusion facilities

In addition to individual facilities, a method is needed to compare alternative pathways (using cost, risk, benefit) in an objective and quantitative manner

DOE and the Greenwald subpanel of FESAC (”Priorities, gaps and opportunities: towards a long-range strategic plan for magnetic fusion energy”) also recognizes the need for metrics (http://www.ofes.fusion.doe.gov/fesac.shtml)

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The EU is also pursuing an approach to evaluate current technology readiness

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Technology Readiness Levels represent a systematic methodology that provides an objective measure to convey the maturity of a particular technology.

They were originally developed by NASA, but with minor modification, they can be used to express the readiness level of just about any technology element.

The Department of Defense has adopted this metric to evaluate the readiness levels of new technologies and guide their development to the state where they are considered “Operationally Ready”.

The Department of Energy has adopted the use of TRL’s in their evaluation of the GNEP program.

Can fusion energy benefit from this approach to develop the technologies needed for Demo?

The US Government Accountability Office (GAO) encourages “a disciplined and

consistent approach for measuring technology readiness”

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Generic description of readiness levels

TRL Category Generic Description

1Concept

Development

Basic principles observed and formulated.

2 Technology concepts and/or applications formulated.

3 Analytical and experimental demonstration of critical function and/or proof of concept.

4Proof of Principle

Component and/or bench-scale validation in a laboratory environment.

5 Component and/or breadboard validation in a relevant environment.

6 System/subsystem model or prototype demonstration in relevant environment.

7Proof of

Performance

System prototype demonstration in an operational environment.

8 Actual system completed and qualified through test and demonstration.

9 Actual system proven through successful mission operations.

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Characteristics of TRL’s

TRLGeneric Description Characteristics of TRL

1 Basic principles observed and formulated.

Pure research. Basic properties. Does not require a specific application.

2 Technology concepts and/or applications formulated.

Practical application of ideas identified. Could be speculative.

3Analytical and experimental demonstration of critical function and/or proof of concept.

Development has begun. Proof of concept obtained. Demonstration of an experimental process in the lab, concept-specific modeling.

4Component and/or bench-scale validation in a laboratory environment.

Concepts from TRL2 integrated into a low-fidelity version. A “playable” demonstration.

5Component and/or breadboard validation in a relevant environment.

Alpha version: demonstration under real-life conditions or a decent simulation, high degree of scaling, low degree of integration.

6

System/subsystem model or prototype demonstration in relevant environment.

Beta version of system: relevant environment, small degree of scaling, moderate degree of integration, higher management confidence

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Characteristics of TRL’s, cont’d.

TRLGeneric Definition Characteristics of TRL

7 System prototype demonstration in an operational environment.

Full system prototype in a relevant environment.

8Actual system completed and qualified through test and demonstration.

Actual system (not a prototype) qualified through test and demonstration. Product ready for full implementation.

9Actual system proven through successful mission operations.

Product in use. Actual system operated successfully. Final stage of development. Expansions or upgrades require separate TRL’s.

GAO recommendation: “Direct DOE Acquisition Executives to ensure that projects with critical technologies reach a level of readiness commensurate with acceptable risk – analogous to TRL 7 – before deciding to approve the preliminary design and commit to definitive cost and schedule estimates, and at least TRL 7 or, if possible, TRL 8 before committing to construction expenses.

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Example of TRL’s for GNEP*:fast reactor spent fuel processing

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Example of TRL’s for GNEP*, continued:

fast reactor spent fuel processing

*Global Nuclear Energy Partnership

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How can we apply this to fusion energy?

1. Use criteria from utility advisory committee to derive issues (roll back)

2. Connect the criteria to fusion-specific (design independent) technical issues and R&D needs

3. Describe Technology Readiness Levels for the key issues

4. Define the end goal (design) in enough detail to evaluate progress

5. Evaluate status, gaps, facilities and pathways

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Utility Advisory Committee“Criteria for practical fusion power

systems”

Have an economically competitive life-cycle cost of electricity

Gain public acceptance by having excellent safety and environmental characteristics No disturbance of public’s day-to-day

activities No local or global atmospheric impact No need for evacuation plan No high-level waste Ease of licensing

Operate as a reliable, available, and stable electrical power source Have operational reliability, high

availability Closed, on-site fuel cycle High fuel availability Capable of partial load operation Available in a range of unit sizes

J. Fusion Energy 13 (2/3) 1994.

End-user (Customer)

Power plant requirement

s

Power plant designs

Demo R&D needs

R&D and facilities definition

Pathways

1

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The criteria for attractive fusion suggest three categories of

technology readiness1. Economic Power Production

a. Control of plasma power flowsb. Heat and particle flux handlingc. High temperature operation and power

conversiond. Power core fabricatione. Power core lifetime

2. Safety and Environmental Attractivenessa. Tritium inventory and controlb. Activation product inventory and controlc. Waste management

3. Reliable Plant Operationsa. Plasma diagnosis and controlb. Plant integrated controlc. Fuel cycle controld. Maintenance

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The intent is to be comprehensive based on functions rather than physical

elements

Power flows

1. Economic Power Productiona. Control of plasma power flowsb. Heat and particle flux handlingc. High temperature operation and power

conversiond. Power core fabricatione. Power core lifetime

Power deposition

Power conversion

IP LPHP

Pout

Compressors

RecuperatorIntercoolers

Pre-Cooler

Generator

CompressorTurbine

To/from In-ReactorComponents or Intermediate

Heat Exchanger

1

2

3

4

5 6 7 8

9 10

1BPin

TinTout

ηC,ad ηT,ad

εrεc

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Example: High Temperature OperationGeneric Description Fusion-specific Description

1Basic principles observed and formulated.

System studies define tradeoffs and requirements on temperature, effects of temperature defined: chemistry, mechanical properties, stresses.

2Technology concepts and/or applications formulated.

Materials, coolants, cooling systems and power conversion options explored, critical properties and compatibilities defined.


Data in static capsule tests and convection loops, modeling of transport phenomena, high-temperature mechanical properties measured.


Capsule and loop operation at prototypical temperatures with prototypical materials for long times.

5Component and/or breadboard validation in a relevant environment.

Forced convection loop with prototypical materials, temperatures and gradients for long exposures.

6System/subsystem model or prototype demonstration in relevant environment.

Forced convection loop with prototypical materials, temperatures and gradients for long exposures integrating full power conversion systems.

7 System prototype demonstration in an operational environment.

Prototype power conversion system demonstration with artificial heat source.

8 Actual system completed and qualified through test and demonstration.

Power conversion system demonstration with fusion heat source.

9Actual system proven through successful mission operations.

Power conversion systems operated to end-of-life in fusion reactor with prototypical conditions and subsystems.

3

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An evaluation of readiness requires identification of an end goal

For the sake of illustration, we are considering Demo’s based on mid-term and long-term ARIES power plant design concepts, e.g.

Diverted, high confinement mode, tokamak burning plasma Low-temperature or high-temperature superconducting magnets He-cooled W or PbLi-cooled SiC divertors PbLi-cooled SiC or dual-cooled He/PbLi/ferritic steel blankets 800˚C (or higher) coolant outlet temperature with high-efficiency Brayton

cycle Advanced power core fabrication processes Efficient autonomous maintenance

4

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5Example evaluation: High temperature operation and power conversion (DCLL)

Concept development is largely completed. Limited data on ex-vessel parts of power conversion system (e.g., HX)

To achieve TRL4: Need full loop operation at high temperature in a laboratory environment

This is typical of many issues; some are more advanced, but most are stuck at TRL=3


Data in static capsule tests and convection loops, modeling of transport phenomena, high-temperature mechanical properties measured.


Loop operation at prototypical temperatures with prototypical materials for long times. Thermomechanical analysis and tests on in-vessel elements (e.g., first wall).

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Summary

The TRL approach has significant advantages Objective metrics for entire range of development Systematic for all plant elements Integrated approach Widely accepted (within the US government)

We have shown that the TRL approach can be applied to fusion energy

The ARIES pathways study will develop a complete methodology and evaluate example concepts TRL’s have been defined for all of the key issues We are preparing to run through an example evaluation of

Demo concepts Analysis of facilities will follow

a methodology for evaluating progress toward an attractive fusion energy source

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