Participants: Sze, Billone, Wong, Bathke, Waganer, D. Lee, Jardin, Kessel, Steiner, Miller, Najmabadi, Malang, Mau, Tillack, El-Guebaly, Sviatoslavsky
Safety and Licensing Summary
D. Steiner noted that Bob Thayer is receiving inputs from GA, ANL, and INEL. He is integrating these inputs into his preliminary safety analyses framework. He hopes to have results to present at the next project meeting.
S. Jardin mentioned that recent Physics Group Conference Call results had been documented in an e-mail message. C. Kessel said he had been in contact with Charlie Neumeyer of Raytheon to discuss the reactive and dissipative power associated with the vertical stability coils. The feedback was that, for this application, an energy storage device (rotating machinery, coil, capacitor) could be used to store the reactive portion of the coil energy. The project team was concerned that the high frequency response might limit the choice or efficiency of the storage system. It was recommended that C. Kessel explore, in more depth, the energy storage design choices with C. Neumeyer and DIII-D power system designers.
C. Wong discussed the progress to resolving the key divertor physics issues. Tom Petrie and Phil West of GA have been working on a radiative divertor approach to dissipate the heat over the first wall surface and lower the local heating in the divertor area to ▓ 5 MW/m2. Additions of argon, krypton, and neon are being investigated. If only a radiative approach is used, the edge electron temperature is too low, e.g. 0.2 eV, and the plasma becomes detached. The current thinking is to also radiate power from the plasma mantle using argon or krypton. By matching the plasma temperature and density provided in the systems code, the mantle layer is about 25 cm. This results in an average heat flux of 0.7 MW/m2 being applied to the entire first wall and a local heat flux to the divertor of 5.7 MW/m2. This mantle thickness can be reduced with a higher edge density which implies a flatter density profile. Petrie will also evaluate the case with a Zeff value higher than the system code value of 1.7 to assess the impact on the plasma equilibium conditions, bootstrap current fraction, and current drive requirements.
C. Bathke mentioned that he has the engineering and physics inputs for the next strawman and is running the code. The first areas to be examined are the coil and plasma. The remainder of the code outputs will be validated by the end of the week (3/15) for release to the project shortly thereafter. The code retains the constant availability option as no new maintenance or reliability data are available. R. Miller has been in contact with Ed Rodwell of EPRI to obtain data on PWR costing and Joe Kirschner of ITER SDJWS to solicit data on costing of ITER elements. Ron is expecting to send a summary of the Starlite costing guidelines and database to Ian Cook by the end of March.
Status of Engineering Design Inputs for Systems Code
All engineering inputs have been forwarded by Laila El-Guebaly to C. Bathke for the next strawman. Mark Tillack mentioned that he and L. Waganer need to improve the documentation of the Engineering (and System?) Design Parameters.
C. Wong mentioned that X. Wang and I. Sviatoslavsky are working with him to help define the engineering of the divertor. The total power has been reduced due to the lowering of the heat flux to the goal value. However, this power reduction impacts the ability to maintain the desired coolant output temperature of 650íC. If lower temperature coolant is unavoidable, the deposited power may be used for feedwater heating or preheating of other circuits. The local geometry, material composition, neutronics, and function (shield, blanket, or structure; replaceable or permanent) are still being iterated to determine the best configuration. There is still discussion regarding size of pipes and location to enable maintenance capability and shielding effectiveness. The size of the maintenance port will probably be slightly increased to accommodate the divertor piping. A decision on the need for and size of the inboard divertor pumping slot will be available in a week. Neutron wall loading on the divertor is 1 MW/m2 average and 2 MW/m2 peak. Laila El-Guebaly will model the FW for the 3-D MCNP code to determine the distribution of the neutron wall loading in the divertor region.
D-K Sze is conducting heat transfer calculations for the blanket and shield with heating inputs from Laila El-Guebaly. The local temperatures will be given to Jake Blanchard for thermal stress calculations. Mike Billone is finalizing the vanadium lifetime criteria (lifetime versus operating stress). This criteria, in conjunction with the expected design stresses, will enable a better prediction of the first wall and blanket lifetime. E. Mogahed and M. Khater are working on the activation and afterheat calculations.
Dennis Lee mentioned the results of a recent call involving several members of the Engineering Group. They discussed the cryostat options, features, and benefits/detriments. The larger common cryostat was adopted with larger port openings (roughly 3 m x 8 m) and a closer fitting envelope. The bottom floor is flat. The clearance from the outer PF coil is 1.25 m to the wall. The upper dome is brought down closer to the upper PF coils, but the exact dimension was not yet determined. Igor Sviatoslavsky suggested the vacuum vessel should provide distributed structural support for all internal components, not just through local supports through the floor. However the current approach of the floor load supports was retained pending further data and analysis. Transfer of the loads between the low temperature shield and the high temperature shield was discussed, but no resolution was noted. S. Malang has been developing a vacuum vessel and cryostat concept that will facilitate removal of a complete sector that is replaceable. D. Lee is evaluating this concept to incorporate as much as possible into the power core configuration. A final concept is dependent upon the geometry of the next strawman.