ARIES Documents -- Meetings ArchiveARIES Conference Call, 5 February 2002
Documented by L. Waganer
Rene Raffray told the group that most of the ISFNT papers have been received for review. He is intending to have all papers reviewed before the ISFNT meeting in April 2002. Farrokh Najmabadi said that he had heard that there might be a modest budget improvement for fusion in FY03.
Ron Miller has extended the target gain curves he showed at the last meeting up to driver energies of 6 MJ.
Wayne Meier reported his continued work on the HI driver code. This code is presently modeling 112 beamlines delivering 6 MJ of beam energy (on target?). He is working with John Bernard and Simon Yu to verify details and modeling accuracy. He is trying to incorporate the system effects of beam emittance. This code is being developed for the thick liquid wall chamber concept. Wayne will prepare a strawman set of parameters for the ARIES group to use.
Wayne Meier presented material provided by Susana Reyes on Waste Assessment and Management. Traditionally, Waste Disposal Ratings (WDR) are used to assess irradiated components from fusion devices. Recycling or clearing the materials may have better public acceptance, so Susana is recommended the use of Clearance Index (CI) as an evaluation index.
This approach was used on HYLIFE-II waste management options. The included table evaluates the major HYLIFE-II components using the waste disposal rating and the Life Cycle Waste Volume (LCWV).
All HYLIFE-II waste is qualified for shallow land burial (WDR < 1), but the Flibe coolant and the confinement building represent sizable volumes to be disposed.
Susana also included a figure of the HYLIFE-II components clearance index ratings (CI) as a function of time after removal from the power core. The stainless steel shells and the flibe will never reach a clearance index less than one in a reasonable time, so these have to be placed in a shallow land burial site. After a year, the power core building materials will attain a clearance value less than one, which would allow that material to be cleared or recycled. Even after a long period of time, the shield remains slightly above a clearance value of one, so it will have to be classified as shallow land burial waste.
Tailoring of the shield materials may improve its clearance properties. Susana also included a figure of the HYLIFE-II components clearance index ratings (CI) as a function of time after removal from the power core. The stainless steel shells and the flibe will never reach a clearance index less than one in a reasonable time, so these have to be placed in a shallow land burial site. After a year, the power core building materials will attain a clearance value less than one, which would allow that material to be cleared or recycled. Even after a long period of time, the shield remains slightly above a clearance value of one, so it will have to be classified as shallow land burial waste. Tailoring of the shield materials may improve its clearance properties.
Lee Cadwallader mentioned that oxygen reaction testing is being accomplished at INEEL on carbon fiber composite test samples to determine reaction rate curves. The preliminary data indicates rate curves lower than those obtained in the initial tests performed in 1988. Theron Marshall will document the data in an upcoming report.
Chamber Wall Engineering
Minami Yoda reported that GT has started simulations of liquid lead injection normal to the chamber first wall using an immersed-boundary method. The GT group already has results for 2D simulations, and will report 3D results at the next ARIES meeting. The isothermal lead films have initial thicknesses of 0.1 or 0.5 mm with injection velocities comparable to repetition rates of 1 to 10 Hz (for reestablishment of film), or 0.01 to 1 cm/s. The inverted surfaces are inclined from zero to 45 with respect to the horizontal (defined as the direction normal to gravity). The objective of these simulations is to determine the onset of the first droplet formation and whether the film "drips" before the next fusion event.
Based on discussions with Said Abdel-Khalik, Minami also raised the issue of whether the overpressure pulse due to X-rays would create problems in terms of driving the film back into the wall, and deadheading the pumps driving this system. This may not be a major issue for two reasons: first, Don Haynes' recent analysis that demonstrated that the overpressure pulse was extremely short; and second, as mentioned by Rene Raffray, the volume of liquid in the chamber is much less than that in the blanket. The 2D results show that the film typically reaches a thickness of about 1 mm before the onset of dripping. Minami asked if this thickness was in the right range.
Don Haynes said he had been using slightly smaller thicknesses, but 1 mm was definitely in the correct range.
The GT group has also started experiments on high-speed water films on downward-facing surfaces, representing liquid injection tangential to the first wall. They plan to study the reattachment of these liquid films around cylindrical penetrations typical of beam and injection ports. GT should confer with UCSD who has done some flow around perturbations and free surface modeling.
RenČ Raffray said that he was working to resolve the action items from the recent ARIES meeting. One of the main items was the definition of the chamber condition requirements for coolant aerosol size and volumetric concentration as determined for beam propagation and target injection/tracking. UCSD is investigating the aerosol formation, growth, and movement within the chamber. The goal is to determine the chamber conditions at the time when the target and beams enter the chamber for the next cycle.
ėSomebodyî discussed the need to model the physical description of the beamline and the vacuum pumping region at the beamline entrance. Leslie Bromberg and Simon Yu will be doing modeling or definition of these subsystems. This is important to assess the neutronic protection of magnets and the isolation of the chamber environment from the beamline.
Simon Yu discussed the beam emittance growth and spot size dependence on the ballistic neutralized (BN) transport through a plasma plug at the chamber entrance. He noted that Dale Welch showed results at the latest ARIES meeting indicating that use of a BN beam in a drywall chamber approach to be feasible. Further work will investigate BN transport at lower gas pressures.
Chamber and Final Optics Nuclear Analysis
Laila El-Guebaly said she was adding Flibe to lead and tin as possible candidate liquid wall materials. She continues to evaluate these materials with regard to the Class C limitation for waste disposal. As she said earlier, lead can be reused up to one year, after which the present lead coolant inventory is disposed of and a new batch of lead is introduced. Tin and Flibe can be reused up to 7 years. Alternatively, 208Bi, Ag, and 14C transmutations can be filtered out on-line to keep using the original liquid wall materials for the plant life. Laila is assuming the high dose first wall coolant is segregated from the bulk blanket coolant/breeder with a lower dose rate. There was also a question as to the coolant volumes within the chamber and the exo-chamber volumes. Les Waganer will examine the Prometheus design to see if that data is available.
Target Injection and Tracking
Ron Petzoldt noted that he is assessing the impact of in-chamber coolant aerosols on the performance of the target and the ability to track the target in the chamber.