# Presentation: 146433

## HIF Chamber Phenomena and Design

**Per F. Peterson, Christophe Debonnel, Philippe Bardet, Grant Fukuda*****Department of Nuclear Engineering***
***University of California, Berkeley***
**2004 International Symposium on Heavy Ion Fusion**** **
**June 7-11, 2004**

**HIF Chamber Phenomena and Design**

## Outline:  Thick liquids can replace fusion materials questions with fluid mechanics questions

**The scaling basis for understanding and predicting thick-liquid IFE chamber performance**
**Robust Point Design 2002 **
**RPD liquid geometries**
**Cylindrical jets**
**Porous slabs**
**Beam-tube vortices**
**Vortex flows**
**Related work with molten salts in fission energy**

## IFE system phenomena cluster into distinct time scales

**Nanosecond IFE Phenomena**
**Driver energy deposition and capsule drive (~30 ns)**
**Target x-ray/debris/neutron emission/deposition (~100 ns)**
**Microsecond IFE Phenomena**
**X-ray ablation and impulse loading (~1 ********s)**
**Debris venting and impulse loading (~100 ********s)**
**Isochoric-heating pressure relaxation in liquid (~30 ********s)**
**Millisecond IFE Phenomena**
**Liquid shock propagation and momentum redistribution (~50 ms)**
**Pocket regeneration and droplet clearing (~100 ms)**
**Debris condensation on droplet sprays (~100 ms)**
**Quasi-steady IFE Phenomena**
**Structure response to startup heating (~1 to 10****4**** s)**
**Chemistry-tritium control/target fabrication/safety (10****3****-10****9**** s)**
**Corrosion/erosion of chamber structures (10****8**** sec)**

**Principal focus for**
**IFE Technology R&D...**

## The HIF Robust Point Design provides the first demonstration of an integrated HIF chamber design

## Flibe x-ray ablation experiments on “Z” can be compared to simpler materials with known EOS’s (LiF, Li metal)

**LiF has been used as a non-toxic, well-characterized surrogate for flibe in recent experiments**
**Experiments at 41 J/cm****2**** match expected wetted wall fluences**
**Koyo (laser chamber)**
**Osiris (heavy-ion chamber)**
**Sesame EOS is available for LiF**
**Gives impulse prediction 10% less than ideal-gas EOS**
**UCB/LANL predicted 2.8 ********m ablation matches 3 - 4 ********m measured with LiF**
**Greater ablation, 4.2 ********m, is predicted for flibe; will be confirmed in upcoming tests**
**Li metal has been tested at higher fluences (~1000 J/cm****2****) under DP programs**
**Time-resolved diagnostics required due to sample destruction**
**IFE samples can be treated with same approach as DP effects testing work**

**Cast and diced Flibe disk**
**being handled in glovebox**

**14 mm**

**5 mm**

**LiF sample exposed to 41 J/cm****2**
**shows clear ablation step**

**0.4 mm**

**Microsecond phenomena**

## Flibe vapor condensation is studied with plasma guns

**Millisecond phenomena**

## Scaled water experiments have demonstrated the capability to form the jets used in RPD-2002

**Re = 100,000**

**High-Re**
**Cylindrical Jets**

**Vortex Layers for**
**Beam Tubes**

**Oscillating Voided**
**Liquid Slabs**

**UCB**

**Millisecond phenomena**

## Navier-Stokes governs liquid hydraulics phenomena

**Major simplifications:**
**   ****No EOS, No energy equation**
**   ****No MHD**

**A scaled system behaves identically**
**if initial conditions and St, Re, Fr,**
**I*, and We are matched...**

**Millisecond phenomena**

## Penreco® Drakesol® 260 AT light mineral oil allows molten salt scaled experiments with low distortion

|  |  |  | Flibe at 600°C | Flibe at 900°C |
| --- | --- | --- | --- | --- |
|  | Oil Temperature |  | 110°C | 165°C |
|  | Length-Scale | Ls/Lp | 0.39 | 0.40 |
|  | Velocity-Scale | Us/Up | 0.62 | 0.63 |
|  | Δ T-Scale | Δ Ts/ΔTp | 0.30 | 0.29 |
| Reynolds Number |  | Res/Rep | 1 | 1 |
| Froude Number |  | Frs/Frp | 1 | 1 |
| Weber Number |  | Wes/Wep | 0.61 | 0.75 |
| Prandtl Number |  | Prs/Prp | 1 | 1 |
| Rayleigh Number |  | Ras/Rap | 1 | 1 |
| Nusselt Number |  | Nus/Nup | 1 | 1 |
| Pumping Power |  | Qps/Qpp | 0.016 | 0.016 |
| Heating Power |  | Qhs/Qhp | 0.009 | 0.010 |

**Adjustable Parameters**

**Millisecond phenomena**

## UCB is now doing detailed experimental measurements of turbulence and surface topology in vortex tubes

**Millisecond phenomena**

## Particle image velocimetry is providing detailed velocity and turbulence information

**Ar CW laser allows visualization of micron particles**
**Water has been replaced by Mineral Oil for improved visualization**
**Evidence for intense turbulence at small length scales**
**crossing streaks in 1000 μs frame suggests eddy frequencies in the kilohertz range**

**If surface-renewal frequency is 1 kHz, 2MW/m****2**** is possible with a surface temperature 50°C greater than bulk temperature**

**Millisecond phenomena**

## UCB has begun studies of combined blowing and suction to keep liquid layers attached to large, concave surfaces

**Blowing is generated using patterns of small holes in the wall, supplied by a pressurized plenum**
**Suction rate depends on layer velocity, surface radius of curvature, and layer thickness**
**Layer thickness adjusts itself to keep injection and suction flow rates equal**
**Both injection and suction nozzles are protected by the liquid layer**

**Millisecond phenomena**

## Modular solenoid HIF chamber could potentially use a large-scale vortex flow

**Issues:**
**Using injection and suction to maintain vortex flow on substrate with non-uniform radius**
**Response of liquid layer to x-ray ablation (surface waves, substrate stresses, droplet ejection)**
**Effects of turbulent surface renewal on ****surface temperature and condensation**

**Vortex generation has been**
**demonstrated experimentally**

**Millisecond phenomena**

## A simple device was constructed to provide proof of principal

**A test device was fabricated from a short segment of cylindrical pipe (22.5-cm diameter)**
**Eight pressurized plenums provided blowing flow**
**Perforations between injection plenums provided suction**
**A****suction**** = 2A****injection**
**End walls produced modest non-ideality**

**Millisecond phenomena**

## Liquid accumulated during startup can be cleared

**t = 2.0 sec**

**t = 7.0 sec**

**t = 14.0 sec**

**The first viability issue for large-vortex flows is removing excess liquid during startup**
**UCB experiments demonstrate that this can be done by providing sufficient suction area**
**After startup, flow dumps on suction drains can be closed, and pressure recovery can be achieved**
**reduce pumping power**
**increase layer thickness**

**stable layer established**

**Millisecond phenomena**

## Now a new large vortex experiment is under construction

**Uses precision fabrication of injection and suction holes**
**Test stand now under trials**

## UCB is studying the injection/suction scheme for complex geometries

**Chamber volume: 80m****3**
**Liquid volume: 28m****3**
**Open fraction of solid angle: 2.4%**

**Millisecond phenomena**

## The Next Generation Nuclear Plant (NGNP) provides opportunities to develop molten salt technology

**NGNP “Artist’s Conception”**

**The Next Generation Nuclear Plant (NGNP) provides opportunities to develop molten salt technology**

**Molten salt heat transfer loop?**

**Fusion Overlaps:**
**•  ****Tritium management**
**•  ****High-temperature materials**
**•  ****High efficiency helium gas-cycle**
**     ****power conversion**

## UCB has completed a pre-conceptual design study for a MCGC power conversion system

**Physical arrangement based on the GT-MHR PCU (vessels are ~ 30 m high)**

**Components fit in four pressure vessels**

**Pre-conceptual design allows comparison of “molten coolant gas cycle (MCGC)” versus gas-cooled reactor power conversion**
**Based on GT-MHR PCU design**
**Includes detailed calculations for MS-to-He heat exchangers**
**Results for high-temperature design**
**2400 MW(t)**
**900°C turbine inlet temp.**
**54% thermal efficiency**
**1300 MW(e)**
**Power density comparison**
**GT-MHR:  230 kW(e)/m****3**
**MCGC:  360 kW(e)/m****3**
**Additional MCGC savings expected due to non-nuclear grade turbine building**

- H. Zhao and P.F. Peterson, “A Reference 2400 MW(t) Power Conversion System Point Design for Molten-Salt Cooled Fission and Fusion Energy Systems,” Report UCBTH-03-002 (Rev. B), Jan. 10, 2004.

**Quasi-steady phenomena**

## A scaled comparison of the 1380 MWe ABWR turbine building and ~1300 MWe MCGC equipment

**MCGC turbine building must also contain crane, turbine lay-down space, compressed gas storage, and cooling water circulation equipment**
**MCGC requires ~1100 MWt of cooling water capacity, compared to 2800 MWt for ABWR**

**The MCGC can likely achieve a substantial reduction of the turbine building volume**

**ABWR**

**He-MCGC**

**Quasi-steady phenomena**

## Conclusions

**RPD-2002 provided the first integrated chamber design for an IFE system**
**Assisted pinch transport chambers are small extrapolations from current HIF chamber designs**
**Vortex flows are interesting and have substantial promise**
**Potential for very high surface heat fluxes**
**Issues:**
**droplet ejection from surface**
**effects of ablation impulse loading**
**control of flow for complex geometries**
**The Next Generation Nuclear Plant will advance and demonstrate key fusion chamber technologies**
**advanced materials**
**molten salt heat transfer fluids**
**materials compatibility**
**target debris recovery**
**helium Brayton cycle power conversion**
**tritium safety and management**