1. Poloidal Distribution of ARIES-ACT Neutron Wall Loading L. El-Guebaly, A. Jaber, D. Henderson Fusion Technology Institute University of Wisconsin-Madison http://fti.neep.wisc.edu/UWNeutronicsCenterOfExcellence Contributors: A. Robinson, T. Bohm, R. Slaybaugh, B. Smith, E. Marriott (UW), X. Wang (UCSD) ARIES Project Meeting UCSD San Diego, CA January 26 - 27, 2011

2. 2 ARIES-ACT Geometry 10/2010 or 1/2011 Strawman Key parameters: R = 5.5 m a = 1.375 m Elongation = 2.2 Fusion power = 1907.4 MW Surface areas: –Plasma = 475 m 2 –Wall area: IB FW = 134 m 2 OB FW = 285 m 2 IB & OB FW= 419 m 2 –Upper & lower divertors: IB plate = 26 x 2 m 2 Dome = 34 x 2 m 2 OB plate = 33 x 2 m 2 Div total = 185 m 2 FW + Div Surface area = 604 m 2 1/16 th Sector (X. Wang) Machine Ave NWL (MW/m 2 ):(P f x 0.8/area)ASC @ plasma surface3.22.2 @ FW + divertor2.6? 5 m

3. 3 Neutronics Code and Model 3-D Codes: –MCNP: for neutron and gamma transport –MCNPX: for neutron, gamma, and charged particle transport –DAG-MCNP: for neutron, gamma, and charged particle transport with added capability to import geometry directly from CAD. 3-D NWL model: –Includes plasma boundary, IB & OB FW, and divertor IB&OB plates and dome. –FW and divertor segmented vertically and radially to improve accuracy –One million particle history –Statistical error < 1% –Neutron source sampled from plasma. MCNP 3-D Plot

4. 4 Neutron Source Sampling Options: 1.Uniform within plasma boundary – unrealistic, but used to check geometry 2.Three-nested regions (with peak at magnetic axis) - good approximation, but data unavailable 3.Actual distribution – exact method : –Source density distributed on R-Z grid –Data not available (to be provided by C. Kessel). MCNP 2-D Plot Uniform Source

5. 5 Inboard Results Source DistributionUniformActual Machine Ave NWL (P f x 0.8/area) : @ plasma surface3.23.2 @ FW + divertor2.62.6 Peak IB NWL ~2.8TBD(> 2.8) Ave IB NWL ~2.4TBD IB FW Peak IB NWL

6. 6 Outboard Results Source DistributionUniformActual Machine Ave NWL (P f x 0.8/area) : @ plasma surface3.23.2 @ FW + divertor2.62.6 Peak OB NWL ~3.6TBD(> 3.6) Ave OB NWL ~3.5TBD OB FW Peak OB NWL

7. 7 Divertor Results Source DistributionUniformActual Machine Ave NWL (P f x 0.8/area) : @ plasma surface3.23.2 @ FW + divertor2.62.6 Peak div NWL ~3.5TBD(< 3.5) Ave div NWL ~1.2TBD Peak Div NWL

8. 8 Summary of Results Source DistributionUniformActualASC Machine Ave NWL (P f x 0.8/area) : @ plasma surface3.23.22.2 ? @ FW + divertor2.62.6 Peak IB NWL ~2.8TBD Ave IB NWL ~2.4TBD Peak OB NWL ~3.6TBD Ave OB NWL ~3.5TBD Peak div NWL ~3.5TBD Ave div NWL ~1.2 TBD

9. 9 Comments of CAD Drawing IB & OB scrape off layers at midplane are 8.5 cm thick – inconsistent with ASC. Straight IB FW? IB FW should conform to plasma to: –Reduce nuclear heating at magnet –Allow more space for DCLL He/LiPb manifolds –Capture neutrons before reaching divertor. Check location of X-point relative to blanket and divertor: –IB/OB blanket extremities (marked with yellow dots) relative to X-point –Tighten divertor entrance as much as practically possible to reduce neutron leakage –Check flow of IB & OB charged particles to IB & OB divertor plates. IB FW ARIES-ACT OB FW

10. 10 Future Work UW will: –Repeat NWL calculations for actual neutron source distribution. –Perform radiation calculations with actual radiation source distribution. Needed info: –Modified CAD drawing from X. Wang (fix SOL, IB/OB FW height, location of divertor plates relative to X-point) –Actual neutron source distribution on R-Z grid from C. Kessel –Actual radiation source distribution on R-Z grid from C. Kessel.