Meeting 2 Action Items

General Action Items or Observations

APEX will look at all magnetic confinement schemes. It is not limited to tokamaks.
The type of Tokamak (along with its design parameters) to be adapted as guidance in the APEX study was chosen to be ARRIES-RS since it has high power density characteristics. (Alice to check with Mark Tillack (UCSD) and compile typical dimensions and parameters.)
Plasma disruptions, and other plasma transients, will be considered as a non-limiting factor (free factor) in the APEX study. However, any concept to be developed should at least take few (~2) disruptions and demonstrate that plasma startup can be performed. In general, concepts that can accommodate easily off-normal conditions will get credit for this.
Dai Kai Sze will work with each group concept to construct and identify an efficient power conversion system.
Questions regarding safety should be directed to the Safety Group (K. McCarthy) once they arise (by e-mail, no waiting).
Perform nuclear analysis to assess guidelines for concept developers with regard to damage, after heat, activation, etc. (M. Youssef, M. Sawan). Also, agree on methodology to be used in the more detailed stage to evaluate tritium self sufficiency. In particular, agree on what type of 3-D heterogeneous calculations to be done for tritium breeding.
Several P/FW/B/VV/C configurations to be explored and evaluated. These are:
a. Conventional: P/FW/B/VV1/C/VV2
a. Variation 1: P/FW/VV1/B/C/VV2 Blanket outside VV
a. Variation 2: P/FWCB/B/VV1/C/VV2 FW is a conductance barrier
a. Variation 3: P/FW/B/C/VV1/VV2 VV outside coil
a. Variation 4: P/FW/B/VV1/VV2 Vacuum Vessel is TF Coil

Specific Action Items

Mohamed Abdou suggested that Protecting FW Liquid could be the only material inside the VV in order to simplify mainenance. He requested evaluation of the various areas related to this: The protection requirements of the VV in this geometry (e.g. 1 ppm He, dpa limits, etc.) will be checked through nuclear analysis (M. Youssef). Mechanical Design Group (Brad Nelson) will examine how this configuration simplifies maintainability and how the protecting liquid layer could be formed. The kind of coolant in the VV will be explored (H2O, He, hydrogen-bearing material, Li, etc.). Kathy McCarthy will talk about hydrocarbons next meeting.
Steve Zinkle will provide M. Youssef with “Tables of Materials Properties” to be put on the web. Included with these tables are the properties of Foams (Nasr Ghoniem)
Anter El-Azab will find the limits (stress, temperature) of the materials provided by S. Zinkle. (e.g. Cu-Ni-Be, T-111, Nb-1Zr, TZM, etc.). Hydrogen content in material (e.g. Vanadium) will be considered in affecting these limits.
Explore the possibility of forming gaps in the flowing protecting liquid which could be used for penetration. Additionally, the instability of the magnetic field in the toroidal direction could be a limiting factor to be examined (Neil Morley).
Next APEX Meeting is scheduled to be April 29-May 1, 1998 at UCLA. Alternate Magnetic Confinement Meeting will be held April 27-28, 1998 and arranged by Dale Meade. A person per concept will attend this meeting. Mohamed Abdou will draft a letter about APEX study to this group.
Mike Ulrickson (SNL) and Clement Wong (GA) will examine a base FW of Tungsten and Vanadium with Helium cooling system and assess the merit of these combinations on carrying away HHF. UCLA will assist in the analysis as needed.
Perform elastic-plastic analysis for stress evaluation and operating limits (Anter El-Azab).
Brad Nelson will assist each concept group to develop a design that incorporates reasonable margins and simplifies maintainability. He will stay with UCLA group after this meeting for that purpose.
The Physics Interface Group (Dale Meade) will do the following:

Critical review of impact of evaporated liquid (lithium, lead ) on plasma performance. Examine allowable evaporation rate and sputtering limits (there is a sputtering report about lead on the web, Mike Ulrickson)
Define the plasma functional requirements that should be met to start plasma. (heating, fueling, control field, removing alpha particles, etc.)
Provide UCLA (and others) with a representative bremsstrahlung spectrum with typical line radiation from impurities (agree on a standard temperature profile and categorize/parameterize it for impurities). Currently, M. Youssef (UCLA) is using ITER plasma radiation for surface heating and will compare impact of various spectra on volumetric heat deposition in Li, Flibe, and Li17Pb83 liquid layers.
Provide definition of representative physical penetration (circular, rectangular, triangular shape and dimension) for heating, fueling, and diagnostics.
Merits/disadvantages of using rectangular FW as opposed to FW that follows the contours of plasma edge. Examine the issue of the need to have a conducting FW (a trade-off question).

The Concepts that will be further examined/discussed next meeting are:

UCLA:

Convective liquid wall (Li, Flibe)
Porous FW filtrated with liquid (non-evaporated)
Thick non-conducting FW

PPPL:

Magnetically restrained thick FW of Lithium (conducting)
– UCLA (N. Morley) will examine the EM forces on the moving liquid (i.e. include MHD in the analysis) which could lead to instabilities. Consider turbulence in the falling liquid layer.

– UCLA (Alice Ying) will examine evaporation of falling liquid as a mechanism to remove heat. Will work with PPPL (Bob Woolley) as needed on its concept.

ANL:

Free Falling Li2O Particulates.
– Dai kai Sze will perform more detailed thermal analysis of that concept by next meeting, including heat exchangers.

Purse using foams in FW (Nasr Ghoniem) and examine evaporation of liquid from FW. Develop a complete thermal hydraulic cycle for that concept by next meeting and improve thermodynamic efficiency.

UW:

Sprayed-FW concept
– UW will purse this concept with analysis to be presented next meeting

By next meeting, each concept proponent(s) will present a plan (~ 18 Months period)