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**National Spherical Torus Experiment (NSTX)**

**Quarterly Report**

**July - September, 1996**

**Executive Summary**

This is the first National Spherical Torus Experiment (NSTX) Quarterly
Report and covers the period from July - September 1996. This was an
especially busy and productive quarter for the NSTX Program and NSTX
Project.

On the NSTX Program side, the quarter was marked by the decision to form
a NSTX Program Advisory Committee (PAC) and three national spherical
torus working groups (STWGs), covering the topics of non inductive
spherical torus (ST) plasma formation, heating and current sustainment,
and high beta and confinement. These STWGs will provide early input to
the NSTX research program preparation activities during FY 1998. These
and other STWGs to be formed in FY 1998 will evolve into the NSTX
national research team during FY 1999.

Additionally, a conceptual design study for the compact ST fusion cores
for the Volumetric Neutron Source (VNS) was discussed at a September
meeting. It was agreed that the NSTX Program will provide the ST fusion
physics input needed by such a study.

On the NSTX Project side, the focus of this period was conducting the
Engineering, Cost, and Schedule Review (ECSR) of the NSTX design. On
July 29 and 30, 1996 a review committee appointed by DOE-OFES met at
PPPL "to obtain expert advice on the engineering design of the NSTX and
on the project's cost and schedule estimate so that reasonable baselines
may be established." The committee's report was issued on September
10,1996. The Project is in general agreement with the findings and
recommendations of the Committee. Additional engineering resources have
been devoted to addressing the issues identified by the international
review team. An action plan is being developed to address each of the
issues and recommendations from the review. As a result of these
recommendations, an aggressive redesign of the center core stack was
initiated.

**NSTX Programmatic Overview**

The major emphasis for this period was organizing the NSTX national
program. Specific accomplishments included:

> • The Program Advisory Committee (PAC) for the NSTX was recently
> formed by Ron Davidson, Director of PPPL. The members of the PAC are
> Ken Gentle (University of Texas-Austin), Ed Lazarus (ORNL), Farrokh
> Najmabadi (UCSD), Gerry Navratil (Columbia University), Bill Nevins
> (LLNL), Stewart Prager (University of Wisconsin), Steve Scott (PPPL),
> Ron Stambaugh (GA), Alan Sykes (Culham, U.K.), and Yuichi Takase
> (MIT). Martin Peng (ORNL) and Masayuki Ono (PPPL) will be ex officio
> nonvoting members. The first meeting of the PAC will take place in the
> Fall, presently scheduled for the mid-November. We look forward to
> working closely with the PAC members in developing a successful NSTX
> research program for the US.
>
> • Formation of three Spherical Torus Working Groups (STWGs) to provide
> broadly based national input on the key NSTX research programs
> preparation activities and the NSTX experiments. The three groups are:
>
> • STWG1: ST Plasma Formation;
>
> • STWG2: Heating and Current Sustainment; and
>
> • STWG3: Stability and Confinement Performance.
>
> The working groups will address the rich spectrum of ST physics
> including Plasma Edge and Scrape-Off Layer, New Diagnostics, and
> Concept Improvement and Plasma Science. It is intended that these
> national STWGs will evolve into the national NSTX Research Team for
> NSTX operations.
>
> • Identification of the NSTX Program as a key contributor of the ST
> fusion physics input needed by conceptual design studies of compact ST
> fusion cores for the Volumetric Neutron Source (VNS) and possibly
> other near-term applications. In providing these contributions, the
> NSTX Program will also make timely improvements to the research
> mission for NSTX and its high performance upgrades to establish the
> data base needed by these near-term ST fusion core applications.

**NSTX Project**

[Tokamak Systems (WBS 1)]{.underline}

> During the early part of this quarter the major focus of the Tokamak
> Systems WBS was preparation for the Engineering Cost and Schedule
> Review. The design of the tokamak was advanced to a conceptual level
> with primary efforts focusing on the centerstack region. Numerous
> analyses of the centerstack, vacuum vessel, coils and supports were
> completed to evaluate the adequacy of the design. Engineering drawings
> describing details of the centerstack region as well as a 3-D layout
> of the entire tokamak were developed. Also included in these
> preparation activities was the development of a Systems Requirements
> Document (SRD), a Systems Design Description (SDD) and a detailed cost
> estimate for completing the design activities and fabrication of the
> tokamak.
>
> In response the review board recommendations, up-front engineering
> design and analysis of the centerstack region were accelerated
> immediately after completion of the ECSR. These efforts focused on
> redesign of the OH solenoid. The transition areas in the solenoid have
> been eliminated. The current design uses a constant cross-section
> conductor for the entire length of the OH winding. This transition
> region was an area of concern because of stress and thermal gradients
> that occur as a result of the changing conductor cross-section and the
> braze joint that would have been required. Additional engineering has
> been applied focused on the characterization of the halo loads in the
> centerstack casing and the development of a thermal insulation system
> for the centerstack that could meet the operational and bakeout heat
> load requirements and survive the high compressive loads caused by the
> halo loads.
>
> Efforts during the first quarter of FY96 will be concentrated on the
> engineering design and analysis of the centerstack. These efforts are
> guided toward final description of the centerstack configuration.
> Details of the thermal insulation and the electrical insulation for
> the coils will be finalized. Methods for supporting and or reacting
> the loads within the centerstack, including halo loads in the casing
> and launching loads in the coils will be developed and analyzed. The
> manufacturing methodology for the centerstack will be developed and
> work on refining the design of the ceramic insulator will continue.

[Heating Systems (WBS 2)]{.underline}

> The major activity for this period was the preparation of the
> conceptual layout, documentation (including the System Requirements
> Document (SRD) and System Design Description (SDD)) and cost estimate
> of the NSTX Auxiliary Heating and
>
> Current Drive systems. While several minor issues were raised about
> the ECH start-up system no major issues were uncovered.
>
> During September a study to look into the possibility of a D-site
> location for NSTX was initiated. Only a minor impact on ICRF was
> found. Most attention was focused on the possibility of using a TFTR
> beam on NSTX. It is important to note that Neutral Beams are not
> included in the NSTX Baseline, but are planned as an upgrade. The
> upgrade path at D-site is more attractive than C-site since one TFTR
> beam can provide 5s, 5MW and 80kV capability. The near term objective
> for the next quarter is to complete the D-site study effort and detail
> the FY-97 scope of work needed to achieve timely construction of the
> ICRF antennas.

[Auxiliary Systems (WBS 3)]{.underline}

> The focus for this last quarter was the ECSR. The documentation
> developed to support this review included the SRD, SDD and a cost and
> schedule baseline. The review included successful presentations of the
> vacuum pumping, gas delivery, glow discharge, coolant, and bakeout
> systems.
>
> The near term objective for the next quarter is to complete the D-site
> study effort and respond to the ECSR issues raised on Auxiliary
> Systems. Auxiliary systems, by their nature, require less technical
> contingency than other systems and focus will be on hardware issues.
> Initiation of the full auxiliary systems design effort is scheduled
> for spring of 1997.

[Plasma Diagnostic Systems (WBS 4)]{.underline}

> The major diagnostic's activity for this period was the preparation of
> conceptual layout's documentation (including the System Requirements
> Document (SRD) and System Design Description (SDD)), and development
> of a cost baseline. The consensus of the review team was:
>
> "The overall plan and estimate budget for the Day-One and Baseline
> diagnostics are reasonable for the expected funding levels of NSTX.
> There is very good use of site credits, and efforts to utilize these
> credits to the maximum extent possible."
>
> The review committee's specific concerns primarily had to do with
> insuring that the critical Day-One and Baseline diagnostics would be
> available when needed. The objective for the next quarter (October -
> December) is to detail and begin the FY-97 scope of work needed to
> achieve this goal, particularly in the area of magnetic diagnostics
> and the challenges associated with locating them on the center stack.

[Power Systems (WBS 5)]{.underline}

> The activity during this time frame was the completion of the
> conceptual design and cost estimate in preparation for the Engineering
> Cost and Schedule Review. The deliverable items for this review
> included the SRD, SDD, drawings, and a cost estimate. As a result of
> ECSR comments and recommendations, the remainder of this quarter was
> devoted to developing a simulation of the OH system that was used to
> arrive at a new monolithic OH coil geometry that matches the power
> supply capability based on a C-site NSTX installation.
>
> Future plans for the next quarter (October - December) include the
> preparation of work plans for the remainder of the project. However,
> other than planning activities and interface issues, the power systems
> activity will not begin to ramp up until Spring 1997.

[Instrumentation and Control Systems (WBS 6)]{.underline}

> The conceptual design, documentation, cost and schedule requirements
> were completed for the Central Instrumentation and Control (Central
> I&C) System and presented at the ECSR. The deliverable items for this
> review included the SRD, SDD, Control Room layout and cost estimate.
> The review committee documented two concerns regarding WBS 6. First,
> the concern that the C-Site NSTX Control Room is too small will be
> resolved by reclaiming adjacent office space to potentially double the
> available C-Site control room area. The detailed evaluation of options
> and costs will be performed in the first quarter of 1997. A second
> concern regarding a low 5% contingency resulted in the project
> adopting a minimum level of 15% contingency from an overall Project
> perspective.
>
> Activities during the last quarter of 1996 (October-December) will
> focus on identifying the technical issues and cost differentials
> associated with placing NSTX at D-Site. The plan is to identify viable
> control systems and data acquisition systems that will best use legacy
> D-site hardware and software, to realize cost savings, yet will
> accommodate the use of new technologies when appropriate.

[Project Support (WBS 7)]{.underline}

> Project Management and Administration
>
> The major activity during this period was preparation, including
> updating the NSTX cost estimate and schedule, for the ECSR. The cost
> estimate was developed using a bottoms-up methodology with maximum use
> of existing equipment and material prices and vendor quotes where
> feasible. As a result, the Construction Estimate (TEC) was estimated
> at \$18.4 M and the Total Project Cost (TPC) at \$20.85 M. First
> plasma is projected for April 1999, based on the funding profile
> guidance provided by DOE.
>
> The NSTX ECSR was extremely beneficial to the NSTX project. We are in
> general agreement with the findings and recommendations of the
> Committee and appreciate the fact that their expertise was brought to
> bear on the Project and available to address some of the challenging
> engineering features on NSTX. As a result of comments and
> recommendations arising out of the ECSR, the Project has re-evaluated
> the amount of contingency, engineering resources, and the cost of
> selected tokamak systems components. The Project's present estimate,
> based on input from the review panel is a Construction Estimate (TEC)
> of \$20.4 M and a Total Project Cost (TPC) of \$23.0M. Attachment 1
> contains the current NSTX Summary Schedule. Attachment 2 contains the
> NSTX Project TEC and TPC broken down by WBS.
>
> In response to specific recommendations and comments provided by the
> ECSR team, NSTX initiated selected rework of the center stack design.
> The results of the rework were promising and resulted in a much more
> robust design. It is planned to hold a checkpoint review of the center
> stack in late October, using a review team composed of internal PPPL
> engineers and several of the ECSR team members.
>
> Project Physics
>
> The Physics team has been working with Engineering over the past few
> months to refine the physics requirements and to aid primarily in the
> effort to address those issues that will be the focal point of the
> late October check-point review. Physics, and specifically the CHI and
> equilibrium physics, have defined the required positions and shapes of
> the PF1a and PF1b coils, and shaping requirements have determined the
> height of the new OH solenoid. Stray field compensation and start-up
> calculations for the new configuration are on-going. Physics has
> provided input for halo current calculations to determine the
> disruptive stresses on the center stack. Heat load requirements for
> Double-Null, Single-Null, and Natural Divertor configurations have
> been given to Engineering; these include both the total power going to
> the divertor plates in the various configurations as well as the heat
> flux profiles. Physics has also provided PF and OH coil current wave
> forms for an inductive scenario of operation from near start-up to
> final OH current shut-down.
>
> D-Site Study
>
> As a result of recommendations concerning future upgrades of the NSTX
> Project, a special study of siting NSTX at D-site, either in the TFTR
> Test Cell or the Hot Cell was initiated late in the quarter. Initial
> indications are that D-site offers some significant advantages for
> upgrade paths, including use of the TFTR neutral beams, compared to
> C-site. The cost and schedule impacts of moving NSTX to D-site are
> being developed and should be completed by mid-November.

[Site Preparation and Assembly (WBS 8)]{.underline}

> During this period Site Preparation and Assembly activities were
> limited to preparing for the ECSR.
>
> Activities planned for the next quarter will focus on finalizing the
> costs for relocating NSTX to D-site in either the TFTR Test Cell or
> Hot Cell. It should be noted that the cost for the assembly of the
> tokamak is independent of whether NSTX remains at C-site or moves to
> D-site.