From: Hutch Neilson
Sent: Tuesday, January 22, 2008 2:38 PM
To: Michael R. Kalish; Arthur W. Brooks; Michael C. Zarnstorff; James L.
Anderson; Don Rej; Phil Heitzenroeder; Mike Williams; Jim Lyon; Mike
Cole; Bob Simmons; Wayne T. Reiersen; William R. Blanchard
Subject: NCSX General Requirements Document (GRD)

Folks,

The GRD, our top-level specification, is the technical basis for the project's new baseline, and will be part of our documentation package.  I am looking through it to see if any updates are needed before we submit our proposal. 

Those identified below are asked to respond by this Friday, January 25, on the following issues:

1.  Vacuum vessel bakeout temperature  (Sect. 3.2.1.2.3.1).  We are providing the capability to bakeout the vacuum vessel shell at 150 C, but I do not know if 150 C port bakeout is in our estimate.  What is our plan?  Kalish

2.  Trim coils for error compensation. (Sect. 3.2.1.5.1)  Our new trim coil design satisfies the baseline requirements to compensate for construction errors. No changes needed, agreed?  Brooks, Zarnstorff

3.  Trim coils for flexibility. (Sect. 3.2.1.5.3.4)  In being responsive to last fall's reviews, we have accepted new (modest) requirements for the trim coils.  It seems they should be documented in the flexibility section.  I propose:
3.2.1.5.3.4.6   Trim coil flexibility
a.  The trim coil set referred to in Sect. 3.2.1.5.1 shall be stellarator symmetric in order to provide upgrade options for additional plasma shape and divertor control flexibility.
b.  The device shall be designed to accommodate the installation of additional trim coils in the midplane region as a future upgrade.
Please review.  Brooks, Zarnstorff, Kalish

4.  Eddy current requirements (Sect. 3.2.1.5.2)   I believe we allowed the MC shell to modestly exceed the 20 ms time constant requirement when we adopted the welded interface, and we are willing to compromise further  by adding the wing restraints should it be necessary to control distortion.  Basically we're accepting increased plasma control risk in order to reduce structural risks.  It seems to me that if we are willing to allow a higher time constant for the MC shell, it makes no sense not to do the same for anything outside of it. We have effectively relaxed the requirement and should change it in the GRD (30 ms?).
Please comment.  Brooks, Zarnstorff

5.  Flexibility. (Sect. 3.2.1.5.3.4)  Remove the TBR's throughout this section. Raises questions. Please comment.  Zarnstorff

6.  Neutral Beam Heating  (Section 3.2.1.5.6.1.1)  Delete the sentence, "One beamline previously used on the PBX-M project will be installed as part of the NCSX Fabrication Project to provide 1.5 MW of neutral beam heating power with a minimum of 0.3 s of pulse length."    The requirement to actually install a beamline disappeared (as a project objective) a long time ago, but apparently was never removed from the GRD.  The change was approved well before the 2005 baseline was approved, so we do not need to go back to it now.  We need to clean this up now, agreed?   Williams, Rej.  

6.  Gas Injection (Section 3.2.1.5.7.2)  We are going back to 3 injectors in order to restore 2005 performance.  The requirement is one per period, each good for 50 torr-l/sec. Is that our design?  Please comment.  Blanchard

7.  Other issues.  Let me know of any concerns.  All

The current GRD is posted at http://ncsx.pppl.gov/SystemsEngineering/Requirements/Specs/GRD/Rev5/NCSX-ASPEC-GRD-05-Signed.pdf

Thank you for your cooperation,
Hutch