Presented by Scott Willms (LANL)

Fusion Nuclear Science and Technology Meeting

UCLAAugust 12-14, 2008

Status of Tritium Processing for ITER

Outline

• Tritium Plant• TEP Design• TEP R&D• TEP Modeling

--The TEP project is being performed as a partnership between SRNL and LANL.

The ITER Tritium Plant is a small chemical plant consisting of seven systems built by multiple PTs

TEP components have been tested at about 1/10th

ITER scale

PMR-US

Caper-FzK

JFCU-JA(US)

ITER Detailed Design Description of TEP process outline – under review

DESIGN

“Build-to-Spec” Design Process

PerformanceSpecifications

Identify Technology Set

Develop PFD andComponent Sizing

Develop P&ID and Equipment List

Glovebox Layout

“SRD”

“Procurement Arrangement”

TEP Interfaces

• GEP stream flows to VDS.

• LTEP stream flows to NB permeators.

• HTEP stream flows to FEP.

• LTEP, HTEP and other interfaces determine IP requirements.

Most major gas streams originate on cryopumps and come to TEP through the Roughing Pump System

Torus

TorusCPs

RoughingSystem

TEPHe (GDC)

ISSSDS

D/T

Wasteto VDS

NeutralBeam CPs

Fueling

Cryopump regeneration separates gas species (thermal desorption spectroscopy)

DT Burn & Dwell – Scenario optimization considerations

DDD calls for two separate systems to process gases from torus and NB cryopumps. Perhaps one is sufficient.

Four standard considerations are:• Sequence: NB CP

regen shifted to follow Torus CP regen.

• T Inventory: N/A• Cooling/Heating:

NB CP regen is not totally constrained.

• Change Needed? Flow from NB CP is “design controlling”. It can be reduced by extending the evacuation period.

Burn Dwell

Minimum NB CPCooling Period

1000 sec B&D with NB Cryopump

TOTAL

Q2

He, Ne

Seq 1 2 3

D2

175 g T ~ 0 g T

Minimum NB CPHeating Period

DT Burn and Dwell – Result of scenario optimization

• Sequence:• T Inventory:• Cooling/Heating:

Extended as much as possible.

• Change Needed?NB CP was “design controlling”, now it is not.

Burn Dwell

1000 sec B&D with NB Cryopump

TOTAL

Q2

He, Ne

Seq 1 2 3

D2

Minimum NB CPHeating Period

Minimum NB CPCooling Period

Present design activities

• Technology evaluation and selection• Process flow diagram preparation and detail

R&D

Reactions

Water gas shift

Methane steam reforming

Catalysts tested

• Catalyst 1: United Catalyst, 60-70% Ni/Al2O3, 1/16” extrusion

• Catalyst 2: Degussa, 0.15% Pt/ 0.15% Pd onAl2O3, 2 mm spheres

• Catalyst 3: NIKKI, 50% Ni on diatomaceous earth, 2 mm pellets

Hydrogen Processing Laboratory

Methane steam reforming – Ni (typical)MSR-NiA-20070214-51 CH4 : 1.99 H2O500 C

Water gas shift – Ni (typical)WGS-NiA-20070125-41.05 CO : 1 H2O500 C

Methane-steam reforming and water-gas shift - Key equations

Arrhenius plot for forward MSR reaction (k1f)

0.0011 0.0012 0.0013 0.0014 0.0015 0.0016 0.00171E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

10900 850 800 750 700 650 600

PtA NiK NiA

k1f (

m3/

mol

/s)

1/T (1/K)

T (K)

Example comparison of model to experiment-MSR over NiA

0.0 0.5 1.0 1.5 2.0 2.5 3.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7 MSR-NiA-20070214-51 CH4 : 2 H2O500 C

Model Exp H2O H2O H2 H2 CO CO CH4 CH4

CO2 CO2

Mol

e Fr

actio

n

Residence Time (s)

By removing hydrogen as it is produced, thermodynamic barriers are circumvented and process can be greatly simplified

MODELING

TEP modeling phases

• Outline Model (Complete)– Evaluate the capabilities of Aspen Dynamics– Provide a basic understanding of system behavior

• Evaluation Model (Current Emphasis)– Support technology selection– Support process flow diagram development

• System Model– Support PI&D development

• TEP-Wide Control Model– Support control system design– Support operating procedure development

• Tritium Plant Model (Proposed)– Develop a model of the entire ITER tritium plant

Present modeling activities

• Aspen unit operations models– Plug-flow reactor model– Permeator model– Palladium membrane reactor (PMR) model– Pump models

• TEP system modeling• Support of TEP technology evaluation• Tritium Plant model• Component modeling (if time permits)

– PERMCAT model

30

Retentate Material Balance

• Aspen Dynamics model contains a transient material balance equation for a plug-flow reactor

• Aspen uses a sub-model to calculate net generation rate or consumption of each species from all reactions in the model

• Need to add a term to account for permeation

ε ⋅ ∂Ci∂t

= − 1V⋅ ∂Fi∂ξ

+ ri −AmV

⋅Gi

for i = H2 : GH2 =2 ⋅ K p

Dout ⋅ ln Dout Din( )⋅ PH2 +ε − PH2 ,perm( )for i ≠ H2 : Gi = 0

Permeation term added to Aspen Dynamics model

31

Benchmark Test Results

32

Response to 50°C Temperature Decrease

38% CO2

14% CO

0.44% H2O

0.33% H2

0.04% CH4

0.42% H2O

0.38% H2

0.65% CH4

13% CO

Conclusions

• The ITER TEP project is– successfully addressing many practical tritium processing issues– solving a number of long-standing issues– changing traditional views of ITER and fusion tritium processing

systems• The ITER TEP project does not have the mission or

time/funding to– study the science behind some of the behaviors being observed– study promising directions for improvement