Status of US ITER Neutronics Activities

1
Status of US ITER Neutronics Activities

• Outline
• Examples of US activities during EDA
• US ITER neutronics activities in the past year
• Possible future US contribution to ITER
  neutronics activities

2
US Neutronics Computation Capabilities

• The US has been developing state-of-the-art
  computational tools and data bases for nuclear
  analyses
• Most recent versions of codes and data will be
  used in ITER nuclear analysis
• Transport codes MCNP5 (Monte Carlo), DANTSYS3.0
  (ONEDANT, TWODANT, THREEDANT), DOORS3.2 (ANISN,
  DORT, TORT)
• Activation Codes ALARA, DKR-Pulsar, REAC
• Data Processing Codes NJOY99.0, TNANSX2.15,
  AMPX-77
• Nuclear Data ENDF/B-VI, FENDL-2
• Sensitivity/Uncertainty analyses FORSS, UNCER

3
U.S. has been Active Participant in ITER Nuclear
Analysis During CDA and EDA
Examples of US Contribution

• Nuclear assessment of breeding blanket options
  and magnet shield optimization during CDA
• Contributed to development of complete integrated
  MCNP ITER (EDA) model that includes details of
  shielding blanket modules, divertor cassettes, VV
  with ports, TF coils, PF coils, CS coils
• Modified MCNP allowing it to sample from actual
  pointwise neutron source distribution in ITER
  plasma
• Calculated poloidal neutron wall loading
  distribution at FW and divertor cassette plasma
  facing surface

4
3-D Nuclear Analysis for Divertor Cassette

• Determined nuclear heating (W/cm3) profiles in
  divertor cassette
• Calculated radiation damage in cassette
  components
• Evaluated adequacy of VV and TF coil shielding by
  calculating hot spot damage, gas production and
  insulator dose
• Performed 3-D divertor cassette pulsed activation
  calculations to determine radioactive inventory,
  decay heat, and radwaste level
• Assessed streaming effects

5
Neutronics Assessment of Divertor Diagnostics
Cassettes

• Nuclear parameters in waveguides
• Streaming through viewing slots
• Nuclear parameters in mirror assemblies

6
2-D R-q Modeling of Two Test Modules Placed in
Test Port
Distance from plasma center
Earlier Work -1996
Two Test modules of the EU Li4SiO4 helium cooled
design are placed in the test model Edge-on
Arrangement A lattice consists of FS layer (0.8
cm), Be bed layer (4.5 cm) and SB bed layer (1.1
cm) Buffer zone between modules (10 cm) Upper
module has 75 Li-6 (19 lattices), lower module
25 Li-6 (16 lattices) Lower attenuation (higher
flux) behind beryllium layers
Cos q
7
Dose Rate (mS/h) in ITER Building During
Operation and After Shut Down
2-D Model of ITER Machine
Coupled 2-D and 3-D Calculations using
Deterministic method (DORT and TORT codes) for
neutron and gamma flux calculations and
DKR-Pulsar code for dose calculations
One Week after Shutdown
2-D Model of ITER Building
Tritium Building 3-D modeling
8
Verification of ITER Shielding Capability with
Various Codes and Nuclear Data
Participants in this Task US/JAERI for thick
shield experiments EU/RF for thin shield
experiments
R-Z model of SS316/Water assembly
Data Verified Various reaction rates, neutron
and gamma spectra, heating rates
R-Z Model of the simulated Super conducting
magnet in SS316/Water Assembly
SSShelf-shielded data- SS316/water assembly
9
US Nuclear Support for ITER Restarted Following
US Rejoining ITER in 2003
Major effort has been in support of ITER TBM
program

• A study was initiated to select two blanket
  options for US ITER-TBM in light of new RD
  results
• Initial conclusion of US community is to select
  two blanket concepts
• Helium-cooled solid breeder concept with ferritic
  steel structure
• Dual-Coolant liquid breeder blanket concepts with
  ultimate potential for self-cooling
• a helium-cooled ferritic structure with
  self-cooled LiPb breeder zone that uses SiC
  insert as MHD and thermal insulator
• a helium-cooled ferritic structure with low
  melting-point molten salt

10
DEMO Blanket Testing in ITER

1. Detailed design of realistic DEMO Blanket
2. DEMO relevant TBM designed
3. TBM inserted for testing in ITER port

ITER
Blanket
DEMO
11
Assessment of Dual Coolant Liquid Breeder
Blankets in Support of ITER TBM
DC-Molten Salt
DC-PbLi
12
3-D Calculation for DC MS
Cross section in OB blanket at mid-plane

• Total TBR is 1.07 (0.85 OB, 0.22 IB). This is
  conservative estimate (no breeding in double null
  divertor covering 12)
• 3-D modeling and heterogeneity effects resulted
  in 6 lower TBR compared to estimate based on
  1-D calculations
• Peaking factor of 3 in damage behind He manifold

13
Preliminary Neutronics for DC PbLi Blanket
Nuclear energy multiplication is 1.136 Peak
nuclear heating values in OB blanket o FS 36
W/cm3 o LL 33 W/cm3 o SiC 29 W/cm3
Blanket thickness OB 75 cm (three PbLi
channels) IB 52.5 cm (two PbLi channels) Local
TBR is 1.328 OB contribution 0.995 IB
contribution 0.333 If neutron coverage for
double null divertor is 12 overall TBR will be
1.17 excluding breeding in divertor region. To
be confirmed by 3-D neutronics Shield is
lifetime component Manifold and VV are
reweldable Magnet well shielded
14
Two Types of Helium-Cooled SB PB modules under
consideration for Testing in ITER
Type 1 Parallel Breeder and Multiplier
Type 2 Edge-On configuration
NWL 0.78 MW/m2 75 Li-6 enrichment Packing factor
for Be and Li4SiO4 Pebble beds 60
Local TBR 1.2 In Demo Configuration- 1-D
Local TBR 1.04 In Demo Configuration- 1-D
15
Neutronics module under evaluation to ensure that
design goals are met
Goals

• Determine geometrical size requirements such that
  high spatial resolution for any specific
  measurement can be achieved in scaled modules
• Allow for complexity, to maximize data for code
  validation

• Proposed scheme is to evaluate two design
  configurations simultaneously however 2-D (3-D)
  neutronics analysis must be performed to ensure
  that design goals are met.
• Demo Act-alike versus ITER-optimized designs
• Structural fraction
• 23 Demo Vs. 21 ITER
• Total number of breeder layers/layer thickness
• 10 layers/13.5 cm Vs. 8 layers/14.9 cm
• Beryllium layer thickness
• 19.1 cm vs. 17.9 cm

16
2-D R-theta Model developed for DORT discrete
ordinates calculations to analyze the nuclear
performance of the US two sub-modules with actual
surroundings
Close-up radial details
Details of Theta variation at the Port
Top View
17
Nuclear Heating in FW of The Two U.S. Test
Blanket Configurations in the Toroidal Direction
Toroidal Profile of Tritium Production Rate in
each Breeder Layer of the Two Test Blanket
Configurations

• Profiles are nearly flat over a reasonable
  distance in the toroidal direction where
  measurements can be performed with no concern for
  error due to uncertainty in location definition
• Steepness in profiles near the edges is due to
  presence of Be layer and reflection from
  structure in the vertical coolant panels

18
US will Contribute to ITER Nuclear Analysis

• US Contribution to ITER Nuclear Analysis will be
  in the following areas
• Nuclear analysis for ITER TBM
• Nuclear support for basic ITER Machine
• Development of CAD/MCNP interface
• Level of effort will depend on availability of
  funding

19
Nuclear Analysis for TBM

• TBM designs will be developed and modeled for 3-D
  neutronics calculations with all design details
• The TBM 3-D model will be integrated in the
  complete basic ITER machine 3-D model
• Perform 3-D neutronics calculations using the
  integrated model
• Neutronics calculations will provide important
  nuclear environment parameters (e.g., radiation
  damage, tritium production, transmutations,
  radioactivity, decay heat, and nuclear heating
  profiles in the TBM) that help in analyzing TBM
  testing results

20
Detailed Nuclear Analysis is Needed for ITER
Basic Machine During Design and Construction
Phases

• ITER is still undergoing major design changes
• As ITER moves toward construction, more accurate
  nuclear analysis becomes essential part of final
  design process
• Experience shows that neutronics and radiation
  environment assessments continue through final
  design and construction phases of nuclear
  facilities
• Examples include
• TFTR and JET
• Spallation Neutron Source

21
Nuclear Analysis for ITER Basic Machine

• This will include computation of radiation field,
  radiation shielding, nuclear heating, materials
  radiation damage, and absorbed dose to insulators
  and other sensitive components
• Three-dimensional neutronics calculations will be
  performed using MCNP5 and FENDL/MC-2.0
• Activation analysis will be planned to support
  safety assessment of the site-specific issues as
  needed. This includes calculating radioactive
  inventory, decay heat, and maintenance dose
• Activation calculations will be performed using
  the state-of-the-art ALARA pulsed activation code
  along with the FENDL/A-2.0 activation data
• Radiation leakage through holes and other
  penetrations must be fully assessed to establish
  activation levels for personnel access

22
Neutronics Support for Module 18 of FW/Shield
(Baffle)

• We will provide neutronics support for design and
  construction of module 18
• 3-D neutronics calculations using the full ITER
  model will be performed to determine nuclear
  heating and radiation damage in components of
  module 18

Module 18
23
ITER diagnostics landscape
24
Nuclear Analysis for Diagnostics Ports

• Many diagnostics systems will be employed in ITER
  at upper, equatorial and lower ports
• Neutron and gamma fluxes affect diagnostics
  performance
• Determination of radiation environment is
  essential for estimating shielding requirements
  for diagnostic components such as insulated
  cables, windows, fiberoptics and transducers, as
  well as detectors and their associated
  electronics
• Radiation leakage through penetrations in these
  diagnostic systems must be fully assessed to
  establish activation levels in and near
  diagnostic equipment where frequent access will
  be necessary
• We will coordinate with diagnostics group to
  provide needed nuclear support

25
Neutronics Support for Heating and CD Systems

• Will support Ion Cyclotron and Electron Cyclotron
  heating and current drive systems
• These systems have sensitive components
  (antennas, RF sources, gyrotrons, insulators, and
  transmission lines) and neutronics support will
  be essential to address radiation damage and
  streaming issues

We will coordinate with plasma heating group to
provide neutronics support as needed
ITER ion cyclotron system block diagram
26
Neutronics Support for ITER Central Solenoid
27
CAD-Based MCNP
Fusion TechnologyInstitute
Parallel Computing Sciences Department

• Use Sandias CGM interface to evaluate CAD
  directly from MCNP
• CGM provides common interface to multiple CAD
  engines, including voxel-based models
• Benefits
• Dramatically reduce turnaround time from
  CAD-based design changes
• Identified as key element of ITER Neutronics
  analysis strategy
• No translation to MCNP geometry commands
• Removes limitation on surface types
• Robustness improved by using same engine for CAD
  and MCNP
• Provides 3rd alternative for CAD-MCNP link
• Can handle 3D models not supported in MCNP
• Status prototype using direct CAD query from
  MCNP
• Issues/plans
• (Lack of) speed 10-30x slower than unmodified
  MCNP
• Key research issue ray-tracing accelerations
  (lots of acceleration techniques possible)
• Support for parallel execution (CGM already works
  in parallel)
• Goal speed comparable to MCNP, but using direct
  CAD evaluation

ARIES-CS Plasma