# Presentation: 080929

## VLT Topical AreaFuel Cycle

- Scott Willms
- Los Alamos National Laboratory
- Presented at
- DOE Germantown
- August 25, 2005

## Fuel Cycle VLT Mission and Scope

- 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

## Key R&D thrust areas over the next five years

- Thrust 1:  Fuel cycle dynamic modeling
- Thrust 2:  Permeation-based separations
- Thrust 3:  TEP supporting research
- Thrust 4:  Tritium separation and control in blanket systems
- Thrust 5:  Continuously regenerable cryopump
- Thrust 6:  Water detritiation
- Thrust 7:  In-vessel tritium removal/processing
- Thrust 8:  Tritium accountability

## Description of R&D Thrusts

## Thrust Area 1:  Fuel cycle dynamic modeling

- ITER Tritium Plant risk assessment performed
- The most striking observation is that, compared to present experience, the ITER Tritium Plant is
- 10x’s flowrate (or more)
- 10x’s inventory (or more)
- 1/10th the processing time

## Industrial-class dynamic simulation needed

- Roles for a Tritium Plant dynamic model
- Process design
- Scale-up
- Control
- Tritium inventory
- Fundamental understanding
- Knowledge capture
- Training

## Thrust Area 2:  Permeation-based separations

- Equipment layout needed now
- Experimental testing needed at blanket conditions
- Tritium migration in TBM needs evaluation

- Baseline has been cryogenic molecular sieve.  Considerable work performed on this.
- However, cryogenic molecular sieve is 77 K and blanket is around 700 K
- During ITER EDA discovered that Pd/Ag permeators can be used to remove small amounts of tritium in inert gases

## Thrust Area 2:  Permeation-based separations

- Low concentration tritium from helium
- Primary stream:  e.g. ceramic breeder
- Secondary stream:  e.g. heat exchanger permeate
- Low concentration tritium in liquid breeder (e.g. PbLi)
- Tritium bound in chemical forms (link to Thrust area 4)
- Membrane reactor
- Superior membranes
- Superior geometries

## Dual Coolant Lead Lithium TBM tritium processing overview

- Use He to strip T from PbLi

- T permeation thru HX tubes

- Recover tritium from He

- Recover tritium from He

*He loop*

*He loop*

*PbLi loop*

- Avg. T2 breeding rate:  0.024 sccm

*Tritium control important throughout*

*Also use as test station*

## Task Area 3:  TEP supporting research

- Current TEP design has only been tested at FzK, and they have not performed integrated testing (this is planned)
- Indications that fundamental parameters have not been tested
- These parameters are particularly important for scale-up
- May need H/D testing of reactor/permeator train to determine parameters

## Palladium Membrane Reactor

- CD-1 review encouraged considering alternates to present ITER TEP design.  PMR possibly shrinks and simplifies the TEP.
- PMR recently chosen for industrial application and design completed
- New industrial membranes may improve performance

## Task Area 4:  Tritium separation and control in blanket systems

- Primary separation method evaluation:  Bubble column, permeator, disengager, oxidation/adsorption, etc.
- Fate and control evaluation:  System design, barriers, etc.

## Extraction strategy depends on tritium “migration” paths

- Large surface area in heat exchanger (req. for heat exchange) results in large loss of tritium through heat exchanger
- Must process cool side of heat exchanger
- Need tritium extractor in main loop?

## Task Area 5:  Continuously regenerable cryopump

- Completed initial tests of pump with H and D, and He
- Successfully fed up to 40 SLPM (current ITER exhaust rate is 91 SLPM)

## Task areas 6-8

- Thrust Area 6:  Water detritiation (EU?)
- Thrust Area 7:  In-vessel tritium removal/processing (mostly other program elements/other parties)
- Tritium removal
- Tritium processing
- Thrust Area 8:  Tritium accountability (EU/ITER?)

## Current spending on R&D Thrusts

- No VLT fuel cycle funding

## Characterization of R&D thrusts to VLT missions

|  | ITER Base machine | R&D needed for ITER to be successful | ITER as test bed (TBM, etc) | Next generation technology (for current and future machines)
Non-tritium machines | Longer Term R&D |
| --- | --- | --- | --- | --- | --- |
| Modeling | x | x | ? |  | x |
| Permeation-based separation |  |  | x |  | x |
| TEP supporting | x | x | ? |  | x |
| TBM tritium processing |  | x | x |  | x |
| Cryopump |  |  | ? |  | x |
| Water detrititation | x | x |  |  | x |
| In-vessel tritium removal and processing | x | x |  |  | x |
| Tritium accountability | x | x |  |  | x |

## Summary

- Fuel cycle research is needed
- To ensure the success of ITER
- To learn from the opportunities afforded by ITER
- To face the new challenges of tritium breeding
- To lay the groundwork for future machines
- Work in many of the fuel cycle areas requires a unique skill set.  This skill set is broadly applicable to other subsystems.