ARIES Program
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ARIES-Pathways Project Meeting Minutes

6-7 September 2007

Idaho National Laboratory, Idaho Falls, ID

Documented by L. Waganer

Organization ARIES Pathways Project
Boeing Waganer, Weaver (Phone)
General Atomics Schultz (phone), Turnbull (phone)
Georgia Tech  
INL Cadwallader, Petti, Sharpe
PPPL Kessel (Phone), Meade (phone), Zarnstorff (phone)
UCSD Dragojlovic, Malang, Mau, Najmabadi, Raffray, Wang
UW-Mad El-Guebaly

Ref: Agenda and Presentation Links: Meeting Agenda


Welcome – Phil Sharpe welcomed the ARIES team to Idaho Falls. He provided snacks and refreshments for the group. Les Waganer reviewed the meeting agenda.


Highlights of 2nd IAEA TM on 1st Generation of Fusion Power Plants - Laila El-Guebaly reported on her recent attendance at the 2nd IAEA Technical Meeting on the First Generation of Fusion Power Plants in Vienna, June 20-22, 2007. She was an invited speaker and presented some results from the ARIES-CS study. David Maisonnier discussed the technological and engineering challenges of fusion power plants. Many presentations focused on the scope and role of Demo. The EU and China were very interested in building a demo. The main thrust is to accelerate Demo as much as possible using ITER physics and today’s technologies (fast track approach). There was a discussion of the Korean Demo that uses He-cooled ferritic steel structure with stagnant Li. The Indian Demo contains a ceramic breeder cooled with lithium lead. India is planning on having a test blanket in ITER. David Ward (EU) is promoting a pulsed Demo to ease the current drive requirements (Mike Zarnstorff questioned the pessimism on the current drive. It has been demonstrated on Tore Supra). Laila presented an overview of ARIES-CS in-vessel components and the proposed radwaste management approaches. She was asked to consider tungsten as a first wall material on ARIES-CS to reduce surface erosion and tritium retention.

G. Janeschits promoted an ultra fast track approach to build Demo, perhaps initiating the design in 2015, construction within 10 years and operation in 2025. The facility envisioned is a large 8.5 m machine with NWL around 2 MW/m2 and maybe a He-cooled ceramic breeder blanket. There are many different definitions and scope of Demo in the various fusion countries including pulsed operation with energy storage. US has traditionally favored an advanced physics and technology version. All countries will probably have their own demo and the international fusion community will benefit greatly from building several demos that satisfy the official definition for Demo.

The final day was devoted to non-electric applications and socio-economic impacts. Economics did not seem to be as important to other countries. Per Ian Cook, 50% of cost is due to the energy source with the remainder being the infrastructure costs - “Focus on Safety, not Economics”,“Do as soon as possible.” The Chinese are planning to build 3 power plants per year to meet the high energy demand by 2050. They foresee a CO2 problem and nuclear energy would help. There is a short supply of uranium. Fusion would be attractive as breeder and transmuter. Chinese would like to build Demo as soon as possible, promoting a super fast track. Next IAEA meeting is scheduled in two years.

Plans and General Scope (of ARIES Pathways Study)

Farrokh Najmabadi commented that his original project schedule anticipated a three-year duration with the first year establishing the groundrules and objectives and the final two years focusing on the details of the plan. The systems code development needs to be accelerated so the trades can be accomplished. An interim report on the technical working groups is to be completed by December 2007. This assessment is very timely as the EU is also working on a similar project.

The date for the next telecon was selected to be 27 September. Farrokh Najmabadi said that the Advisory Committee should meet with the ARIES team at the next meeting to provide them a more in-depth briefing. He suggested the meeting be held in Atlanta, either in late November or early December (the latter is more favored by the team). Les Waganer will send out queries on the potential dates.

Status of Advisory Committee Involvement

Ken Schultz has been working on the minutes of the June Advisory Committee meeting. It was suggested that the minutes format be changed into an informal report with an introduction on the background and important issues. Then he should provide an outline of the key issues identified by the Committee, such as steady-state operation, risk averse customers, use of advanced simulation and modeling, development of supply chain, higher availability (~95%?), and no disruptions.

At the next Advisory Committee meeting (December 2007), the ARIES team should provide a more in-depth view of engineering and physics assessments that have been accomplished, what is our vision, and what is the basis for our Demo (ARIES-AT?).

ARIES-TNS Systems Code Development

Progress on Systems Code Development - Zoran Dragojlovic presented his current results on modeling the TF coils as compared to the ARIES-AT baseline. TF coil algorithms from Leslie Bromberg have been incorporated. Shielding material thicknesses were obtained from Laila El-Guebaly and incorporated. The TF coil cross-section was shown along with current density and magnetic field plots. The densities and costs for several coil materials were provided, but the cost values need to be confirmed, especially the cost of HTS conductors for the commercial facility. The results are encouraging and Zoran believes he can complete this portion in 2 months. It was recommended that Zoran determine the reason for the discontinuities in the cost curves on his page #18. Laila suggested comparing the magnet composition with the reference ARIES-AT's.

The next phase will be the definition of the TF interconnecting structure and the PF coils in conjunction with Chuck Kessel and Leslie Bromberg.

Progress on Systems Cost Accounts and Algorithms - Les Waganer described his progress in developing the cost accounts in more detail. He reviewed his prior efforts in adding the land and land rights and structures and site facilities. He showed an example of the ARIES-AT cost account reporting which was considered to be incomplete. Les proposed a more complete accounting system in an Excel spreadsheet. Laila suggested adding an account for low temperature shielding. She also suggested that he breaks down the reactor systems into categories, rather than a complete grouping of subsystems, e.g., power handling, coils, current drive/heating/fueling, structures, and ancillary systems (power supplies and vacuum systems).

Les illustrated his technique for adjusting the cost basis for differing years to be considered. He is using the US Commerce Department, Bureau of Economic Analysis that has a Gross Domestic Product (GDP) indexed to inflation. Mike Zarnstorff mentioned the cost may not just scale with inflation, but with higher cost of tools and equipment.

Progress on Systems Code Development and Physics Validation - Chuck Kessel described his progress on the PF coil algorithm modeling. The PF coils also include the central solenoid coils. The initial set of PF coils will be a large number of coils that reside outside the TF coil envelope. After a viable solution is found, the number of coils will be reduced with an equivalent field structure. This is necessary to accommodate maintenance and service ports and other geometry constraints. Chuck is using Zoran's new TF configuration as a representative of the ARIES-AT shape.

Chuck is trying to define the out of plane structural requirements for normal and off-normal conditions. Les Waganer noted that during the AT study; Leslie Bromberg considered the most stringent design condition was an off-normal condition caused by the loss of current in one TF coil. It was suggested a conference call be convened with all parties interested in the design conditions for the out-of-plane structure.

Laila asked Chuck to check and confirm the need for 2-mm W coating on the FW to improve the physics performance of the ARIES designs.

Instrumentation and Controls - Tom Weaver (Boeing) described McDonnell Douglas' (now Boeing) prior involvement in fusion and particularly the I&C aspects. The recent trends in I&C of large systems is moving away from the previous standard of federated (physically distributed) controls toward a more integrated controls that actively control all the functionality of the facility in an integrated manner. This results in more optimized, flexible, and adaptive system with the benefits of plant health monitoring and prognostication (higher reliability and less downtime), higher levels of security and utilization. Aerospace applications have been the leaders in this technology evolution.

Magnet Codes and Issues - Leslie Bromberg did not attend and this subject was not covered.

Physics limitations and their impact on engineering design of Demo - Alan Turnbull highlighted the key issues the TNS project needs to address to balance the physics and engineering constraints:

  • Disruption limits (consider in 2008/09)
  • Power handling and ELM/Sawtooth suppression (consider in 2008/09)
  • Discharge shape, profile control, and operations (consider in 2010+)
  • Advanced operation (consider in 2010+)

Alan proposed to address these issues in the years noted by identifying the key physics issues and formulating specific physics questions that would answer the engineering issues. Alan then discussed each of these issue categories and posed a set of questions to address the issues along with some proposed answers. Rene thought these data should be utilized in the Working Groups to help focus on the critical issues and needed R&D. Several people pointed to fusion experiments that helped address some of these issues.

Radwaste Management Issues - Laila El-Guebaly visually compared the radwaste volumes of ITER and several other MFE conceptual power plant studies, noting that the volume of radwaste generated with fusion is several times that of fission (more low level, less high level). This translates into high disposal costs for future fusion power plants due to limited low level waste (LLW) repositories and political difficulty to construct new repositories. Laila emphasized this point with specific disposal cost data. Recycling and clearance offer more attractive approaches to minimize the volume of active materials but have many issues to be addressed. They should be pursued despite the lack of detail on how to implement them now. The U.S. industrial experience indicated a cost saving in recycling lead shielding bricks versus disposal in U.S. LLW repositories. And the properties of recycled stainless steel alloys were very similar to those of fresh alloys after removing the slag.

Relevancy of Titian Results to Demo Program (Explorations toward Fusion Power Performance - Phil Sharpe outlined the 6-year TITAN program background involving Japanese and US R&D facilities focusing on LiPb. The principle concern is matching the power handing systems into an integrated system. The objectives were to obtain a fundamental understanding of tritium and thermo-fluid control throughout the FW, blanket, HX, and tritium recovery systems when exposed to critical fusion operating conditions. Phil discussed the program tasks to address each aspect of the issues.

Exploring Capability to Calculate Heat Loads on Divertors and First Walls - TK Mau discussed the need for a heat load analysis tool to address power management and plant operation. He illustrated the parameters to be calculated in the power management tool. The tool will address heat loads that originate from the scrape off layer/divertor regions as well as the plasma core and edge radiating mantle. UEDGE codes are potential tool candidates. TK showed some UEDGE calculations for ARIES-AT and FIRE. Core radiation results were obtained from the MIST and STRAHL codes. TK will work with LLNL to assess the ARIES-TNS power handling trade studies.

Effective Power Management in Demo: Work Necessary to Prove Feasibility and To Increase Attractiveness - Siegfried Malang discussed all the areas where (thermal) power management is critical to the success of a commercial power plant, namely power density in power core, first wall, breeding blankets, divertor target plates, ancillary systems for heat and tritium extraction and power conversion systems. Siegfried then expanded on each of these areas pointing out the critical aspects and factors of each area. In the core, the peaking factors for NWL and surface heat fluxes should be minimized. In the FW, the design parameters must be optimized to meet the maximum allowable heat flux. There are several breeding blanket options to be considered, each with a unique set of advantages, disadvantages and needs, which Siegfried discussed. There are significant technical challenges for the divertor to handle the heat flux and high energy alpha particles, have an acceptable lifetime and reliability, and capture the thermal energy for conversion. Ancillary system issues are dependent on the blanket choice. The issues are how to extract the thermal energy from the blanket and divertor systems and transport that energy to the Brayton energy conversion system while limiting the tritium release to the atmosphere. The closed loop Brayton power conversion has been chosen as it can deliver the highest level of thermal to electrical energy conversion and it eliminates any chemical reaction between steam and reactive blanket materials. Scale up from present components is needed along with compatibility with fusion materials and conditions.

Siegfried suggested that the dual coolant lead lithium blanket with helium-cooled reduced activation ferritic steel (RAFS) and SiC flow channel inserts would be the better blanket choice for Demo because it is based on the well known ferritic/martensitic RAFS as structural material and can be tested in the time frame of ITER. The divertor would be helium-cooled with a tungsten alloy structure. The power conversion systems would be the closed loop helium Brayton cycle. The permeator would be a refractory alloy structure for the primary lead lithium coolant loop for tritium extraction down to < 1 Pa. The DCLL concept is already a good compromise between the required extrapolation of present day technology, and the desired Demo performance. It also has the potential for an attractive future power plant as it is on the pathway to an advanced power plant with self-cooled lead lithium blankets based on SiC-composite as structural material.

ARIES-TNS Technical Working Groups

Power Management Technical Working Group: Status and Documentation - Rene Raffray summarized the relationship between ITER and Demo and gaps to be identified and addressed to minimize the risk to building Demo. The Technical Working Groups were formed to help identify and define those technology gaps and propose R&D plans and facilities to resolve those gaps. Rene discussed in more detail the role and schedule of the Power Management TWG. He has prepared an outline of the Power Management interim report.

Tritium Fuel Management TWG - Phil Sharp noted he has been swamped and has not had time to address the TWG goals.

Plant Operations TWG - Les Waganer described the purpose of the Demo plant operations is to achieve a high level of plant availability by employing state-of-the-art I&C and RAM hardware and processes. The primary objective is to minimize the operational risk to the potential investor. Les outlined the purpose, scope, members, and plans of the Operations TWG.

Wrap-up of Meeting

Farrokh Najmabadi introduced the concept of Technical Readiness Levels (TRL) to the ARIES group. This approach of analytically assessing and categorizing the technical readiness of hardware components or software was originated with NASA and then has been adopted by the Department of Defense to better understand the development of components and systems. A more complete explanation of the DoD TRL Calculator is provided at this web site that describes and compares the NASA and DOD TRL definitions and describes a calculator that determines the TRL of any component or software. The TRL approach is widely used throughout the aerospace community to determine the level of development. Les will help introduce the concept to the team.