Fusion Neutronics Activities in USAReported for the Neutronics Groups at

UCLA, UW, and TSI Research, Inc.

byE.T. Cheng

TSI Research, Inc.P.O. Box 2754

Rancho Santa Fe, CA 92067U.S.A.

Workshop on Sub-Task Fusion Neutronics under IEA Implementing Agreement on a Co-operative

Program on the Nuclear Technology of Fusion Reactors

21 September 2004 (SOFT)Venice, Italy

Fusion Neutronics Activities at the University of Wisconsin at Madison

• Neutronics Analysis in Support of ITER Test Blanket Modules– Assessment of Dual Coolant Liquid Breeder

Blankets, Molten Salts and PbLi– Three Dimensional Modeling and Calculations

• Development of CAD-based MCNP

• Development of Activation Code, ALARA– Availability: Distribution by RSICC (ORNL)

Assessment of Dual Coolant Liquid Breeder Blankets in Support of ITER TBM

Assessment of Dual Coolant Liquid Breeder Blankets in Support of ITER TBM

DC-Molten Salt

DC-PbLi

He Outlet Pipe

He Inlet Pipe

Grid Plates

Back Plate

First Wall

SW/FW He Inlet/Outlet

Manifold

He Flow Inlet Distribution Baffle

LL Flow Outlet Distribution Baffle

3-D Calculation for DC MS 3-D Calculation for DC MS

Be zone Perforated plates

FW Coolant channels

Front Flibe Zone, Flow Direction Poloidal Up

Back FLiBe Zone, Flow Direction Poloidal Down

He Manifold Separator plate,

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

Blanket thicknessOB 75 cm (three PbLi channels)IB 52.5 cm (two PbLi channels)

Local TBR is 1.328OB contribution 0.995IB contribution 0.333

If neutron coverage for double null divertor is 12% overall TBR will be ~1.17 excluding breeding in divertor regionShield is lifetime component

Manifold and VV are reweldable

Magnet well shielded

Nuclear energy multiplication is 1.136Peak nuclear heating values in OB blanket

o FS 36 W/cm3

o LL 33 W/cm3

o SiC 29 W/cm3

Preliminary Neutronics for DC PbLi BlanketPreliminary Neutronics for DC PbLi Blanket

Parallel Computing Sciences Department

CAD-Based MCNP

Use Sandia’s 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

» 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

Fusion TechnologyInstitute

CGMACIS Pro/E Voxels

MCNPMCNPNative

Geometry

ARIES-CS Plasma

Clothespin, w/helical spring surface

Activation Code Development

• ALARA - Version 2.7 available for use– Exact modeling of pulsed/intermittent sources– “Reverse” mode for efficient calculation of rare products– Direct calculation of:

• Waste disposal rating• Contact dose

• Total shutdown heating• Biological dose (requires source-to-

dose adjoint calc)

– Continuing development:• Sequential charged particle reactions• More data format/type support

• Monte Carlo activation code under development

alara.engr.wisc.eduwilsonp@engr.wisc.edu

Relative difference between EAF and IEAF decay heat calculations in IFMIF HFTM

Fusion TechnologyInstitute

Fusion Neutronics Activities at the University of California at Los Angeles

• Neutronics Analysis in Support of ITER Test Blanket Modules– Activation Analysis of Dual Coolant Molten

Salt Liquid Blankets– Design Analysis of Solid Breeder, Pebble-Bed

Test Blanket Modules– Two Dimensional Discrete-Ordinates Code,

DORT

Comparison Between Total Activity and Decay Heat in Each

Material in the Flibe and Flinabe Dual Coolant Blankets

10-5

10-4

10-3

10-2

10-1

100

101

102

103

104

105

10-1

100

101

102

103

104

105

106

107

108

109

1010

1011

F82H (Flinabe Breeder)

Flinabe with tritium

Be (Flinabe Breeder)

F82H (Flibe Breeder)

Flibe with tritium

Be (Flibe Breeder)

Time after Shutdown, sec

1 s 1 m 1 h 1 d 1 mo 1 y 10 y 100 y 1000 y

Total in 8.3-m long Inboard and Outboard Modules

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

10-1 100 101 102 103 104 105 106 107 108 10910101011

F82H (Flinabe Breeder)Flinabe with tritiumBe (Flinabe Breeder)F82H (Flibe Breeder)Flibe with tritiumBe (Flibe Breeder)

Time after Shutdown, Sec

1 s 1 m 1 h 1 d 1 mo 1 y 10 y 100 y 1000 y

Total in 8.3-m long Inboard and Outboard Modules

•The activity generated in Flibe is larger than in Flinabe by a factor of 1.5-2 in the time frame of few days to few years after shutdown. However, there is an appreciable contribution to the total decay heat in Flinabe that is attributed to the generation of Na-24, up to few hours, and to the production of Na-22 up to several years following shutdown.

0.1

1

10

0 10 20 30 40 50

Nuclear Heating Rate in the Li4SiO4 BreederWall Load= 0.78 MW/m2

Breeder1 100%

Breeder2 100

Distance from Front Edge, cm

DCPB TBM with Parallel Breeding zones

0.1

1

10

0 10 20 30 40 50

Nuclear Heating Rate in the Beryllium Multiplier Wall Load= 0.78 MW/m2

BE Be1 100Be Be2 100Be Be3Be Be4 100

Distance from Front Edge, cm

DCPB TBM with Parallel Breeding zones

NWL 0.78 MW/m2

75% Li-6 enrichmentPacking factor for Be and Li4SiO4 Pebble beds 60%

Two Types of Helium-Cooled SB PB modules under consideration for Testing in ITER

Type 1: Parallel Breeder and Multiplier:

Local TBR: 1.2In Demo Configuration- 1-D

Type 2: Edge-On configuration

Local TBR: 1.04In Demo Configuration- 1-D

0.1

1

10

0 10 20 30 40 50

Heating Rate in the Breeding UnitNWL= 0.78 MW/m2 zone 4 Fe 100

zone 4 be 100zone 5 fe 100zone 5 be 100zone 6 fe 100zone 6 be 100zone 7 fe 100zone 7 be 100Br fe 100Br be 100br br 100

Distance from front edge (cm)

Li4SiO4 Breeder

Beryllium

Structure

Neutronics module under evaluation to ensure that design goals are met

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

• To determine geometrical size requirements such that high spatial resolution for any specific measurement can be achieved in scaled modules

• To allow for complexity, to maximize data for code validation

Goals

Top View of the U.S. and Japan Test Blanket Modules Placed in a ½ Port in ITER

2-D R-theta Neutronics Calculation to Analyze the Nuclear Performance of the US TBM with Actual Surroundings

Calculation Model

Calculation by DORT-Discrete Ordinates Transport Code, 46 neutron-21 gamma groups

6.5

7

7.5

8

8.5

9

9.5

0 10 20 30 40 50 60 70

Toroidal Distance from Frame, cm

d (distance from front edge, mm)

d= 0 mm

d= 10.5 mm

d= 21 mm

Left Configuration Right Configuration

Nuclear Heating in the First Wall of the Two U.S. Test Blanket Configurations in the Toroidal Direction

•Toroidal heating rate is nearly flat over a distance of ~10-14 cm (left Config.) and ~16-20 cm (right Config.)

• Heating rate measurements could be performed over these flat regions with no concern for error due to uncertainty in location definition

Toroidal Profile of Tritium Production Rate (TPR) in each Breeder Layer of the Two Test Blanket Configurations

•Profiles of the TPR is nearly flat over a reasonable distance in the toroidal direction where measurements can be performed (10-16 cm in the left Config. and 10-20 cm in the right Config.).

•Steepness in the profiles near the ends is due to presence of Be layer and reflection from structure in the vertical coolant panels (VCP). This is more pronounced at the outer VCP.

0

1 10-5

2 10-5

3 10-5

4 10-5

5 10-5

0 10 20 30 40 50 60 70

Distance from Frame, cm

Left Configuration Right Configuration

Layer#

Layer#

1

2

3

4

5

6

7

8

9

1

3

2

4

5

6

3

Fusion Research and Neutronics Activities at TSI Research, Inc.

• Application of Fusion Neutrons– Transmutation of Spent Fuel Actinides – U238 Burning Power Plants– Performance of Sub-criticality of Actinides in

Equilibrium in Fusion Blankets

• Nuclear Data for Fusion– Nuclear Data Needs Activities– Review of Helium Generation Data for IFMIF (ANLNDM-158, by Donald L. Smith)