IFE Reactor Chamber Design and Blanket Issues Some Comments

Transcription

1 IFE Reactor Chamber Design and Blanket Issues Some Comments Presented by A. René Raffray UCSD TITAN Workshop on System Integration Modeling on MFE and IFE University of California, Los Angeles Los Angeles, CA February 5, 2008 February 5, 2008/ARR 1

2 IFE Based on Lasers, Direct Drive Targets and Solid Wall Chambers February 5, 2008/ARR 2

3 Example of IFE Energy Source Based on Lasers, Direct Drive Targets and Solid Wall Chambers (HAPL) System (including power cycle) Electricity Generator Target factory Target (fabrication at <20K, survival in chamber during injection) Blanket Dry wall chamber (armor must accommodate ion+photon threat at up to ~ K) Modular Laser Array Chamber conditions (~0.1-1 ev depending on pre-shot conditions) Final optics (+ mirror steering) February 5, 2008/ARR 3

4 What are the Threats on the Chamber Wall? Chamber wall Target microexplosion Example energy partitioning for 350 MJ-class direct drive target (HAPL reference from J. Perkins, Oct. 2005) Direct Drive Target (MJ) X-rays 4.94 (1.3%) Neutrons (74.7%) X-rays Fast & debris ions Neutrons Gammas (0.005%) Burn Product (12%) Fast Ions Debris Ions (16%) Kinetic Energy Total X-ray, ion and neutron fluxes to the chamber wall several times per second. Neutron flux penetrates deeper and not an issue for armor. Need to develop armor that can accommodate X-ray and (more importantly) ion threats. February 5, 2008/ARR 4

5 Ion and Photon Threat Spectra Cover Appreciable Energy Ranges Example spectra for 350 MJ-class direct drive target (HAPL reference, J. Perkins, Oct. 2005). February 5, 2008/ARR 5

6 Ion Power Deposition Occurs in a Very Thin Armor Region (~µm s) over a Few µs q W FS Coolant Example case for m chamber without protective gas to avoid target survival and placement issues. Only thin armor region sees large energy deposition and temperature transients (next slide). This led to the configuration choice of a thin armor layer (~ 1 mm) on a FS substrate. Blanket at the back sees quasi steady state (similar to MFE). W chosen as preferred armor material (high-temperature capability, no tritium concern). Armor lifetime is a key issue and is the focus of the R&D in this area. February 5, 2008/ARR 6

7 Temperature History and Gradient for W Armor in a m Chamber Subject to the 350 MJ-Class Baseline Target Threat Spectra (from HAPL) 1-mm W on 3.5 mm FS at 580 C. No chamber gas. Time-of-flight spreading of ion energy deposition results in much lower temperature rise than assumption of instantaneous energy deposition. Peak temperature ~2400 C. February 5, 2008/ARR 7

8 Impact of Threat Spectra on W Armor Lifetime Several possible mechanisms could lead to premature armor failure: - Ablation. - Melting (is it allowable?). - Surface roughening & fatigue (due to cyclic thermal stresses). - Accumulation of implanted helium. - Fatigue failure of the armor/substrate bond. Ablation Depth No net ablation, but surface roughening Threshold for roughening Threshold for ablation Net Ablation T or ΔT Because the exact IFE ion and X-ray threat spectra on the armor cannot be duplicated at present, experiments are performed in simulation facilities as part of the HAPL program: - Ions (RHEPP@SNL). - Laser (Dragonfire@UCSD). - Fatigue testing of the W/FS bond in ORNL infrared facility. - He management is addressed by conducting implantation experiments (UNC, UW) along with modeling of He behavior in tungsten (UCLA). February 5, 2008/ARR 8

9 Xe Pressure (mtorr) Armor Survival Constraints Impact the Overall IFE Chamber Design and Operation Required P Xe as a Function of Yield to Maintain T W,max <2400 Cfor 1800 MW Fusion Power and Different R chamber 60 R chamber (m) 1 mm W 40 é mm FS T coolant =572 C 6.5 h=67 kw/m 2 -K é B B é é J H J H é é F é é 0 B J H F F Yield (MJ) Example chamber parameters for 0 gas pressure: - Yield = 350 MJ; R=10.5 m; Rep. rate ~ 5 for 1750 MW fusion 1 é February 5, 2008/ARR 9 5 é Repetition Rate W temperature limit of 2400 C assumed for illustration purposes (~1.2 J/cm 2 roughening threshold from RHEPP results) Limit to be revisited as R&D data become available Desirable to avoid protective chamber gas based on target survival and injection considerations Large chamber maintained as baseline for HAPL Possibility of advanced chambers explored, in particular use of magnetic intervention to stir away the ions and help achieve a more compact chamber

10 Self-Cooled Li Blanket for Large HAPL Chamber Large chamber size (R=10-11 m) led to the division of blanket modules in two (upper and lower halves). Annular Li Channel Inner Li Channel February 5, 2008/ARR Sandwich insulator: FS-SiC-FS The design is based on an annular geometry with a first Li pass cooling the walls of the box and a slow second pass flowing back through the large inner channel. Optimized for good performance when coupled to a Brayton cycle via a HX (η up to 49% for ODS FS and TBR > 1.1). 10 Other designs considered as back-up options.

11 Magnetic Intervention: Utilizing a Cusp Field to Create a Magnetic Bottle Preventing the Ions from Reaching the Wall and Guiding them to Specific Locations at the Equator and Poles Utilization of a cusp field for such magnetic diversion has been experimentally demonstrated previously paper by R.E. Pechacek et al., Following the micro-explosion, the ions would compress the field against the chamber wall, the latter conserving the flux. Because of this flux conservation, the energetic ions would never get to the wall. One possibility would be to dissipate the magnetic energy resistively in the FW/blanket, which reduces the energy available to recompress the plasma and reduces the load on the external dumps - about 50-70% of ion energy dissipated in blanket - about 30-50% of ion energy in dump region More details in SOFE 2007 presentation: D. V. Rose, A. E. Robson, D. R. Welch, T. C. Genoni, J. L. Guiliani and J. D. Sethian, "Computational Analysis of the Magnetic Intervention Concept for First Wall Protection from Energetic Ions in KrF Laser Driven IFE, February 5, 2008/ARR 11

12 Biconical Chamber Well Suited to Cusp Coil Geometry and Utilizing SiCf/SiC for Resistive Dissipation SiCf/SiC blanket with Pb-17Li or flibe as liquid breeder (tight assembly of submodules). Armored ion dumps schematically shown inside chamber, but preferably placed outside for easier maintenance access. Water-cooled steel shield is lifetime component and protects the coil (can also be locally placed around coils). Example Chamber Parameters Target yield Neutron/ion/photon energy partition Rep rate Fusion power Total thermal power Cone height/radius Peak/avg. neutron wall load Peak/avg. photon heat February 5, 2008/ARR flux on first wall 367 MJ 0.75/0.24/ Hz 1.84 GW ~2.1 GW 6/6 m 6.1/4.3 MW/m2 0.11/0.08 MW/m2 12

13 Self-Cooled Pb-17Li or Flibe +SiC f /SiC Blanket Optimized for High Cycle Efficiency Simple annular submodule design builds on ARIES-AT concept. Coolant flows in two-pass: first pass through the annular channel to cool the structure; and a slow second pass through the large inner channel where it is heated to a high temperature (>1000 C) while the SiC f /SiC temp. is maintained <1000 C. High Brayton cycle efficiency (~ 50-60%). Magnified View of Schematic Cross-section For flibe, ~1 cm Be layer needed at front of module for tritium breeding and chemistry control. February 5, 2008/ARR 13

14 Self-Cooled Pb-17Li (or flibe) + SiC f /SiC Blanket Coupled to a Brayton Cycle through a He HX 3 Compressor stages (with 2 intercoolers) + 1 turbine stage; ΔP/P~0.05; 1.5 < r p < ΔT HX ~ 30 C - η comp = η turb = Effect. recup = 0.95 February 5, 2008/ARR 14

15 Self-Cooled Blanket Concept Coupled to a Brayton Cycle (Pb-17Li + SiC f /SiC and Flibe + SiC f /SiC) Blanket Rchamber Max. SiC T Max. SiC/Cool T Coolant Tin Coolant Tout Coolant DP Cycle eff. Pb-17Li 6 m 1000 C 900 C 483 C 799 C ~0.3 MPa 50% Pb-17Li 6 m 1100 C 950 C 580 C 930 C ~ 0.3 MPa 55% Flibe 6 m 1000 C 912 C 519 C 700 C ~1 MPa 46% Flibe 6 m 1100 C 1010 C 590 C 790 C ~1 MPa 50% Pb-17Li From simple estimate for flibe with same blanket configuration as Pb-17Li: - Flibe low Re and poor heat transfer properties result in lower cycle η and higher ΔP February 5, 2008/ARR 15 for given SiC f /SiC T max constraint. Need to perform analysis for optimized flibe configuration

16 Integrated Chamber Core (work in progress) Vertical maintenance for core components. Horizontal maintenance for equatorial ion dump (described later). Magnets inside VV and protected by local shield around them. Vacuum pumping done through shielded vertical ducts below the chamber. - An array of 32 turbo-molecular pumps can keep the chamber pressure <0.5 mtorr (low pressure desired for both target survival during injection and to February 5, 2008/ARR prevent charge exchange with the expanding ions). 16

17 IFE Based on Heavy Ion Beam Driver, Indirect-Drive Target and Thick Liquid Wall Chamber February 5, 2008/ARR 17

18 Example of Thick Liquid Wall Concept with Heavy Ion Beam Driver and Indirect Drive (HYLIFE-II) CAD model of HYLIFE-II chamber for the RPD (S. YU et al., An Updated Point Design for Heavy Ion Fusion, Fusion Sci. Technol., 44, 266, 2003) February 5, 2008/ARR Schematic of liquid jets that make up TLW protection 18

19 Energy Partitioning and Photon Spectum for Example 458-MJ Heavy Ion Indirect-Drive Target February 5, 2008/ARR 19

20 Physical Processes in XRay Ablation Volumetric heat deposition in a flibe wall or curtain at 0.5m from the microexplosion for the 458-MJ indirect-drive photon spectra, illustrating the region where explosive boiling is likely to occur. From: A.R. Raffray, S. I. Abdel-Khalik, D. Haynes, F. Najmabadi, P.Sharpe, M. Yoda, M. Zaghloul and the ARIES-IFE Team, "Thermo-Fluid Dynamics and Chamber Aerosol Behavior for Thin Liquid Wall under IFE Cyclic Operation," Fusion Science & Technology, 46, , November February 5, 2008/ARR 20

21 Summary of Simulation Capabilities of Different Models and of Simulation and Measurement Capabilities of Different Experimental Facilities in Addressing IFE Liquid Wall Mechanisms February 5, 2008/ARR 21