# Presentation: 656489

## Relation of US VLT Program to ITER

**by**
**Charles C. Baker**
**VLT Director**
**for the**
**16th ANS Topical meeting on the **
**Technology of Fusion Energy (TOFE)**
**Madison, Wisconsin**
**16 September 2004**

**Relation of US VLT Program to ITER**

## The Enabling Technology Research Mission

**To contribute to the national science and technology**
**base by developing the enabling technology for existing**
**and next-step experimental devices, by exploring and**
**understanding key materials and technology feasibility**
**issues for attractive fusion power sources, by conducting**
**advanced design studies that integrate the wealth of our**
**understanding to guide R&D priorities and by developing**
**design solutions for next-step and future devices.**

## VLT

- Universities
- Industries

**The Technology Program is a **
**Multi-institutional National Resource**

**VLT**

**INEEL**

**LANL**

**LLNL**

**ORNL**

**PNL**

**PPPL**

**SNL**

**ANL**

**UCSB**

**WIS.**

**UCSD**

**UCLA**

**ILL.**

**UCB**

**RPI**

**Maryland**

**GIT**

**Raytheon**

**CPI**

**General**
**Atomics**

**Boeing**

**TSI**

**SRL**

**NRL**

**MIT**

## VLT Magnetics Base Program Support for ITER in 2004

- The Magnetics team has been working on magnet technology issues related primarily to the ITER Central Solenoid.
- Task Agreements are underway in 4 areas:
**1. ****Qualification of industrial suppliers of Nb3Sn strands with increased value of Jc**** (****ITA 11-****18-UA)****. (*****note: strand program uses direct ITER funding*****)**
**2.****	****Stress ****A****nalysis of the ****H****elium Inlet Regions**** (****ITA 11-20****)**
**3.****	****Conductor Performance and Design ****C****riteria **** (****ITA 11-****22)**
**4.****	****CS Jacket Weld ****D****efect Assessment **** (****ITA 11-****23) ****	**
- VHTP
- The US has sent Nicolai Martovetsky/LLNL and Philip Michael/MIT to work with the IT at Naka JWS on CS procurement issues where they are developing specification documents, as well as contributing to other design issues. They each spend several weeks in Naka on an alternating basis at the level of about 0.5 FTE.  This will increase to 1.0 FTE next year.
- Jacket Material Characterization
- Investigation of strand/cable degradation through lab scale test program:
- fundamental characterization of a single strand under pure bending conditions,
- sub-size cables exposed to transverse compressive stress at relevant magnet field, current, and force levels.
- CS Conductor Analysis
- CS Procurement Preparations
- CS Design Activities
- design of the helium inlet,
-  joints design,
- analysis of CS decentering forces

##  Mechanical Properties of Jacket Material JK2LB

- 	JK2LB properties are being characterized to determine if it can satisfy jacket material criteria:
- Yield, tensile, elongation at RT and 4K
- Fracture toughness at RT and 4K
- Fatigue crack growth rate at RT and 4K
- Base metal and weld metal (limited samples)
- Effect of cold work
- Defect inspection

**Cryogenic mechanical test facility at MIT**

##  First Wall Testing for ITER

- Our small electron beam system (EBTS) is being used to determine the capabilities of Plasma Sprayed Be on the first wall.
- Plasma spray is one of the options for applying Be 5-10 mm thick to the copper first wall.
- We are setting up to do fatigue testing up to 3 MW/m2 under steady state conditions.

##  ELM Simulation on Divertor PFC

- One of the two beams on EB-1200 is used to provide normal heat flux
- The other beam is focused to a small spot to simulate ELM heat loads for ~0.1ms
- Thousands of cycles will be completed to determine long term effects of ELMs on PFCs
- This is a very high priority for ITER divertor

## ICRF Base Program Supports ITER R&D and Design Needs

- Base R&D Program is
- Evaluating different design options for load-tolerant ICRF antennas that can operate during ELMs
- General topic, needed for C-Mod, JET, DIII-D
- Applying knowledge gained to ITER antenna design
- Studying high-voltage breakdown properties in presence of plasma and gas
- Needed for near-term domestic programs
- Particularly important for ITER, since antenna will have to operate at 40 kV+  voltages to deliver desired power to the plasma
- Developing and applying improved 3D electromagnetic modeling of antennas to optimize antenna designs
- Using for JET, C-Mod, ITER, DIII-D,....
- Testing antenna designs that may be applicable for ITER
- High-power prototype of JET “ITER-like” load-tolerant antenna

## High Power Prototype (HPP) of JET “ITER-like” Antenna

- US-EU collaboration to test antenna on JET with possible ITER application
- Prototype designed collaboratively between US and EU
- ORNL and PPPL built prototype, tested at ORNL in 2003
- Initial tests achieved original objectives, found ways to improve antenna
- Tested voltage limits in vacuum
- Tested thermal & electrical behavior of components during long-pulse operation

- New test program underway
- Goals
- Test new current strap design to improve power-handling capability
- Show modified antenna can operate for full-current 10-s pulses.
- Test new capacitors with stainless steel internal components.
- Determine operating limits for the JET “ITER-like” antenna

## ECH System/Allocations

**ECH System/Allocations**

- (24) 1 MW, 170 GHz Gyrotrons (EU, JA, RF)

- (3) 1 MW, 120 GHz Gyrotrons (US)

- Transmission Lines (US)

- Equatorial Launcher (JA)

- (3) Upper Launchers (EU)

- (24) DC Power Supplies (not shown) (US)

## VLT Program Plans for ITER

**Design Study of 120 GHz, Start-Up Gyrotrons**
- 1 MW, 120 GHz gyrotron needed; gyrotron operating at up to 2 MW would be useful for both ITER and DIII-D.
- Milestone: Complete design by September, 2005.
**Advances in remotely steerable launcher design** will be made to permit steering at larger angles and with the incorporation of miter bends in the line at GA.
- Now part of design for ITER ECH antennas.
**Industrial 120 GHz Gyrotron for ITER**
- Useful for both ITER and DIII-D.
- Milestone: complete engineering design and fabricate long lead time components by September, 2006.
**Testing of Short Pulse Prototype of 2 MW, 120 GHz Gyrotron at MIT.**
**These tasks will be supported by the US VLT Enabling Technology program for ECH.**

## ITER Fueling System

**ITER Fueling System**

- Gas injection system for edge fueling
- Multiple pellet injectors for deep core fueling, are the primary ITER fuel delivery system.
- Requires long pulse, highly reliable, high throughput, tritium rich pellets
- Significant extension of present-day designs.
- Centrifuge accelerator witha continuous screw extruder.
- Inner wall pellet injection with curved guide tubes

**M. Watson, JET**

## Pellet Injection is Crucial for Effective Core Fueling in ITER as Shown in H-mode Fueling Source Profile Comparison with DIII-D

- D+ 1019 m-3 s-1

**DIII-D**

**Gas puff core fueling in ITER will be much less effective than in DIII-D**
**ITER pellet profiles are from PRL ****(P. Parks)**** ( 10-mm, 1 Hz )**
**gas fueling rate of ~1000 torr-L/s for ITER case ****(L. Owen and A. Kukushkin)** **B2-Eirene slab calculation**

**HFS pellet**

**Gas puff**

## Slide 14

## Slide 15

## Key Accomplishments: Safety and Tritium

- Completed Management Self-Assessment to commence tritium operations up to 1.5 g-T in STAR
- Demonstrated Be as a REDOX agent for molten salt Flibe at high HF concentrations as part of JUPITER-II collaboration
- Measured Flibe mobilization in air and hydrogen behavior in Flibe as part of JUPITER-II collaboration
- Completed analysis of dust from JT-60 and NSTX
- Provided safety support for ARIES, ITER-TBM, APEX and FIRE

## Key systems in STAR

***Molten Salt Tritium Behavior Experiment***

***Tritium Storage and Assay System***

***Tritium Plasma Experiment and Enclosure***

***Tritium Cleanup System***

***Molten Salt  Preparation, Purification, and REDOX Experiments***

***Steam and air chemical reactivity test apparatus***

## Tritium Processing-Overview

- Mission
- To research, develop and design safe and effective tritium processing systems needed to accomplish the OFES mission

- Scope
**Separations**: Many unique separations are required for tritium impurities processing, isotope separation, purification, and gas and water detritiation
**Storage and delivery**: Isotopes must be safely stored and delivered to systems as needed
**Effluent cleanup**: High efficiency cleanup systems are needed to prevent worker & public exposure
**Analysis**: A variety of analyses are required for process monitoring, inventory control and contamination control
**Handling**: Tritium’s unique properties lead to materials compatibility and containment issues
**Control**: Unique control issues arise from the challenge of producing
- 	on-spec product with this radioactive material while maintaining
- 	minimal inventory

## Tritium Processing-Recent Results

- Completed initial testing of a continously regenerable cryopump that can be used for ITER pellet fueling system (Cryogenic Applications/LANL/ORNL)
- Completed initial design of a tritium extraction system for the ITER Test Blanket Module program.  Included evaluation of tritium permeation pathways.
- Performed evaluation of ITER Tritium Plant design.  Plant will be much larger than current knowledge base.  Propose dynamic model to bridge gap.

- Continuously regenerable cryopump in operation at LANL

- Tritium extraction system design for ITER TBM

## US Fusion Materials Research Portfolio

| Material | FY04 budget (k$) | ITER relevance
(incl. TBM) | Program leverage |
| --- | --- | --- | --- |
| Crosscutting theory & modeling | 2000 | 60% | BES, NSF, ASCI |
| Ferritic/martensitic/ODS steel | 2200 | 80% | DOE-NE (Gen IV, INERI, AFCI), JAERI, NRC, BES, LDRD |
| SiC/SiC | 1600 | 40% | DOE-NE (Gen IV, NERI), DOE-NR, JUPITER-II, PBMR |
| V alloys | 1200 | 10% | NASA JIMO, NASA SRTP, DOE-NR (refractory alloys), JUPITER-II |
| Functional materials (MHD insulators, Cu, plasma diagnostics, etc.) | 450 | 40% |  |
| ITER machine R&D | 100 | 100% |  |
| Neutron source | 170 | 0 |  |

## Summary of ITER Fusion Materials Activities

- The US program (in collaboration with JAERI in several cases) provided key materials data during the 1990s for the ITER design
- Type 316 austenitic stainless steel
- Cu alloys for first wall and divertor heat sinks (CuCrZr, dispersion strengthened Cu)
- Beryllium
- Carbon-carbon composites
- Ceramic insulators for plasma diagnostics and heating systems
- Current ITER tasks are focused on critical assessment of properties data for superalloys, Cu alloys, and other materials systems
- Research on a very high strength Cu alloy has also been requested
- In addition to ITER machine tasks, critical data for the ferritic/martensitic steel and other materials for the ITER test blanket modules is being obtained as part of the DOE/JAERI and Jupiter-II collaborations, as well as from the US base program (e.g., SiC compatibility with Pb-Li)

## Next Step Options (ITER/AT)

- •  Successful implementation of AT operating modes in ITER  would increase power densities and pulse duration allowing **extended performance** for physics exploration and nuclear testing.
- •  The goal is to develop ITER/AT scenarios with N ≈ 4, and a bootstrap fraction of ≈75% and to determine the systems requirements so that discharges approaching 1000 MW for ~3000 sec could be produced.
- • The key activities include development of:
- 		•  AT scenarios using integrated self-consistent simulations,
- 		•  MHD stabilization coils compatible with neutron environment,
- 		•  High power density divertor and first wall components, and
- • operating range that exists within system and facility constraints.

**Next Step Options (ITER/AT)**